This document presents an adaptive terminal sliding mode control (ATSMC) strategy for DC-DC buck converters. The strategy uses terminal sliding mode control (TSMC) to ensure finite time convergence of output voltage errors to equilibrium, and integrates an adaptive law to make the sliding line dynamic during load variations. Simulation and experimental results show the ATSMC exhibits faster output voltage response during load changes compared to conventional SMC and TSMC strategies.
This paper investigated the performance of the sliding mode control technique for dc/dc converter using frequency response method. The applications of the step down type switching regulator) buck converter (are found in the devices that use batteries as power source like laptop, cell phones, electric vehicle, and recently, it has also been used in the renewable energy processing, as a maximum output power can be achieved at higher efficiency. In order to optimize the efficiency and for convenient power management, the issues like power on transients, the effect of load variation, Switching and Electromagnetic interference (EMI) losses has to be overcome for which controllers are used. In the proposed method, pulse width modulation (PWM) based on proportional-integral-derivative sliding mode voltage controller (PID SMVC) is designed for a buck converter and the response for appropriate control parameters has been obtained. The system stability has been examined and analyzed from the performance characteristics, which shows clearly that the buck converter controlled by the sliding mode controller has fast dynamic response and it’s very efficient for various applications.
This document describes sensorless current mode (SCM) control, an observer-based control technique for DC-DC converters that provides the benefits of current mode control without requiring a current sensor. SCM reconstructs the inductor current through integration of the inductor voltage. It has significant advantages over conventional current mode control in noise susceptibility and dynamic range. SCM provides both line and load regulation through a single control loop. Experimental results show SCM performs comparably to conventional techniques without noise and better handles noise and wide load ranges. One-cycle control is described as a special case of the general SCM method.
An Improved Repetitive Control for Circulating Current Restraining in MMC-MTDCTELKOMNIKA JOURNAL
The modular multilevel converter (MMC) is widely used in many important application fields such
as high voltage DC transmission system. And the multi-terminal architecture of it attracts many attentions.
However, the circulating current of MMC is an inherent problem which is mainly caused by the voltage
mismatch between arms and DC bus. In this paper, an advanced repetitive control method is proposed.
This method is based on the even-harmonic characteristic of the circulating current and the potential
feature of repetitive control that it has an internal integration part. The pole diagram of the closed loop
transform function of the proposed control system proves the stability of the proposed method. And
according to the simulation results of a three-terminal MMC-MTDC model in PSCAD/EMTDC, the
improved repetitive control presents better circulation repression ability and superior anti-interference
capability by comparing with traditional PI control method. Additionally, the simulation results also indicate
that the proposed repetitive controller can restrain the fluctuation of SM voltage more effectively than PI
control.
PSO and SMC based Closed Loop V/F Control of AC Drive using SVPWMIRJET Journal
This document proposes a particle swarm optimization and sliding mode control scheme for V/F control of an induction motor drive. Space vector pulse width modulation is used to control the motor voltage and frequency, reducing total harmonic distortion. Particle swarm optimization is used as the main controller, while sliding mode control provides stability without requiring precise system knowledge. Simulation results in MATLAB validate the effectiveness of the proposed control system in controlling motor speed, current, and torque.
Performance improvement of parallel active power filters using droop control ...Ghazal Falahi
In this paper, a new method based on droop control scheme is proposed for controlling parallel operation of active filters. The harmonic components of the load current are extracted by an enhanced phase-locked loop (EPLL). In the parallel group, each filter operates as a conductance and the harmonic workload is shared among them. A droop relationship between the conductance and non-fundamental apparent power controls the operation of each unit. The non-fundamental apparent power has been calculated based on IEEE Std 1459. Principles of operation are explained in this paper and simulation results which are presented approve the effectiveness of this method. The results indicate a significant reduction in Total Harmonic Distortion (THD) in a rectifier application.
Voltage Regulation of Boost Converter using Observer based Sliding Mode Contr...TELKOMNIKA JOURNAL
This study dealt with output voltage regulation of boost converter using observer based sliding mode controller comprises of adaptive PI sliding surface. Observer was designed to estimate the inductor current value, such that no sensor was required as a feedback. Adaptive PI sliding surface was constructed from the difference between estimated inductor current and its reference value. The stability of proposed method was ensured by using Lyapunov direct method. To test the system performance, numerical simulation was conducted. The result indicated that the integral absolute error value of proposed method was 0.19, which was 7 times less than sliding mode with PI sliding surface. Consequently, the proposed method was able to estimate accurately the inductor value, track the reference voltage perfectly, and show its robustness against parameter variations.
Speed Sensorless Sliding Mode Control of Induction Motor Using SimulinkIOSR Journals
This document summarizes a research paper that proposes a new sliding mode control method for sensorless operation of induction motors at low speeds. The paper first provides background on induction motors and challenges in their control. It then introduces sliding mode control as a novel nonlinear control technique that can provide robust performance despite parameter variations or load disturbances. The paper describes the control principle of sliding mode control, where the system response is forced to track a predetermined trajectory through switching feedback modes. Simulation results using MATLAB/Simulink show that the proposed sliding mode observer allows sensorless induction motor control at low speeds.
This paper investigated the performance of the sliding mode control technique for dc/dc converter using frequency response method. The applications of the step down type switching regulator) buck converter (are found in the devices that use batteries as power source like laptop, cell phones, electric vehicle, and recently, it has also been used in the renewable energy processing, as a maximum output power can be achieved at higher efficiency. In order to optimize the efficiency and for convenient power management, the issues like power on transients, the effect of load variation, Switching and Electromagnetic interference (EMI) losses has to be overcome for which controllers are used. In the proposed method, pulse width modulation (PWM) based on proportional-integral-derivative sliding mode voltage controller (PID SMVC) is designed for a buck converter and the response for appropriate control parameters has been obtained. The system stability has been examined and analyzed from the performance characteristics, which shows clearly that the buck converter controlled by the sliding mode controller has fast dynamic response and it’s very efficient for various applications.
This document describes sensorless current mode (SCM) control, an observer-based control technique for DC-DC converters that provides the benefits of current mode control without requiring a current sensor. SCM reconstructs the inductor current through integration of the inductor voltage. It has significant advantages over conventional current mode control in noise susceptibility and dynamic range. SCM provides both line and load regulation through a single control loop. Experimental results show SCM performs comparably to conventional techniques without noise and better handles noise and wide load ranges. One-cycle control is described as a special case of the general SCM method.
An Improved Repetitive Control for Circulating Current Restraining in MMC-MTDCTELKOMNIKA JOURNAL
The modular multilevel converter (MMC) is widely used in many important application fields such
as high voltage DC transmission system. And the multi-terminal architecture of it attracts many attentions.
However, the circulating current of MMC is an inherent problem which is mainly caused by the voltage
mismatch between arms and DC bus. In this paper, an advanced repetitive control method is proposed.
This method is based on the even-harmonic characteristic of the circulating current and the potential
feature of repetitive control that it has an internal integration part. The pole diagram of the closed loop
transform function of the proposed control system proves the stability of the proposed method. And
according to the simulation results of a three-terminal MMC-MTDC model in PSCAD/EMTDC, the
improved repetitive control presents better circulation repression ability and superior anti-interference
capability by comparing with traditional PI control method. Additionally, the simulation results also indicate
that the proposed repetitive controller can restrain the fluctuation of SM voltage more effectively than PI
control.
PSO and SMC based Closed Loop V/F Control of AC Drive using SVPWMIRJET Journal
This document proposes a particle swarm optimization and sliding mode control scheme for V/F control of an induction motor drive. Space vector pulse width modulation is used to control the motor voltage and frequency, reducing total harmonic distortion. Particle swarm optimization is used as the main controller, while sliding mode control provides stability without requiring precise system knowledge. Simulation results in MATLAB validate the effectiveness of the proposed control system in controlling motor speed, current, and torque.
Performance improvement of parallel active power filters using droop control ...Ghazal Falahi
In this paper, a new method based on droop control scheme is proposed for controlling parallel operation of active filters. The harmonic components of the load current are extracted by an enhanced phase-locked loop (EPLL). In the parallel group, each filter operates as a conductance and the harmonic workload is shared among them. A droop relationship between the conductance and non-fundamental apparent power controls the operation of each unit. The non-fundamental apparent power has been calculated based on IEEE Std 1459. Principles of operation are explained in this paper and simulation results which are presented approve the effectiveness of this method. The results indicate a significant reduction in Total Harmonic Distortion (THD) in a rectifier application.
Voltage Regulation of Boost Converter using Observer based Sliding Mode Contr...TELKOMNIKA JOURNAL
This study dealt with output voltage regulation of boost converter using observer based sliding mode controller comprises of adaptive PI sliding surface. Observer was designed to estimate the inductor current value, such that no sensor was required as a feedback. Adaptive PI sliding surface was constructed from the difference between estimated inductor current and its reference value. The stability of proposed method was ensured by using Lyapunov direct method. To test the system performance, numerical simulation was conducted. The result indicated that the integral absolute error value of proposed method was 0.19, which was 7 times less than sliding mode with PI sliding surface. Consequently, the proposed method was able to estimate accurately the inductor value, track the reference voltage perfectly, and show its robustness against parameter variations.
Speed Sensorless Sliding Mode Control of Induction Motor Using SimulinkIOSR Journals
This document summarizes a research paper that proposes a new sliding mode control method for sensorless operation of induction motors at low speeds. The paper first provides background on induction motors and challenges in their control. It then introduces sliding mode control as a novel nonlinear control technique that can provide robust performance despite parameter variations or load disturbances. The paper describes the control principle of sliding mode control, where the system response is forced to track a predetermined trajectory through switching feedback modes. Simulation results using MATLAB/Simulink show that the proposed sliding mode observer allows sensorless induction motor control at low speeds.
Investigation of the Common Mode Voltage for a Neutral-Point-Clamped Multilev...IJPEDS-IAES
The purpose of this paper is to provide a comprehensive Investigations and its control on the common mode Voltage (CMV) of the three-phase three-level neutral-point diode-clamped (NPC) multilevel inverter (MLI). A widespread space-vector pulse width modulation (SVPWM) technique to mitigate the perpetual problem of the NPC-MLI, the CMV, proposed. The proposed scheme is an effectual blend of nearest three vector (NTV) and selected three vector (STV) techniques. This scheme is capable to reduce the CMV without compromise the inverter output voltage and Total harmonics distraction (THD). CMV reduction achieved less than +Vdc/6 using the proposed vector selection procedure. The theoretical Investigations, the MATLAB software based computer simulation and Field Programmable Gate Array (FPGA) supported hardware corroboration have shown the superiority of the proposed technique over the conventional SVPWM schemes.
[9_CV] FCS-Model Predictive Control of Induction Motors feed by MultilLevel C...Nam Thanh
Ha Thanh Vo, Nam Thanh Hoang, Phuong Hoang Vu, Minh Trong Tran, Dich Quang Nguyen, “FCS-Model Predictive Control of Induction Motors feed by MultilLevel Casaded H-Bridge Inverter”, RCEEE-2018.
IOSR Journal of Electrical and Electronics Engineering(IOSR-JEEE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of electrical and electronics engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electrical and electronics engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
State-space averaged modeling and transfer function derivation of DC-DC boost...TELKOMNIKA JOURNAL
This paper presents dynamic analysis of a boost type DC-DC converter for high-brightness LED (HBLED) driving applications. The steady state operation in presence of all system parasitics has been discussed for continuous conduction mode (CCM). The state-space averaging, energy conservation principle and standard linearization are used to derive ac small signal control to inductor current open-loop transfer function of the converter. The derived transfer function can be further used in designing a robust feed-back control network for the system. In the end frequency and transient responses of the derived transfer function are obtained for a given set of component values, hence to provide a useful guide for control design engineers.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Low voltage ride through control of modular multilevel converter based hvdc s...Ghazal Falahi
Low Voltage Ride Through (LVRT) is an important grid requirement for Voltage Source Converter (VSC) based HVDC links. This paper studies the performance of the modular multilevel converter (MMC) VSC based HVDC systems during faults or voltage dips and proposes a new control strategy to improve the LVRT performance. The proposed algorithm controls the system to generate the required active and reactive powers that are calculated mathematically based on the ratings of the MMC-HVDC system and LVRT requirements. The injected active and reactive power values obey the LVRT guidelines and are adaptable to different grid codes. The mathematical calculations are presented and EMTDC/PSCAD simulation evaluates the performance of the proposed method.
A Review to AC Modeling and Transfer Function of DCDC ConvertersRadita Apriana
In this paper, AC modeling and small signal transfer function for DC-DC converters are
represented. The fundamentals governing the formulas are also reviewed. In DC-DC converters, the
output voltage must be kept constant, regardless of changes in the input voltage or in the effective load
resistance. Transfer function is the necessary knowledge to design a proper feedback control such as PID
control to regulate the output voltage as linear PID and PI controllers are usually designed for DC-DC
converters using standard frequency response techniques based on the small signal model of the
converter.
Impact of dynamic system modelling on the power stability of hvdc systemsIndra S Wahyudi
This document discusses the impact of dynamic system modeling on the power stability of HVDC (high-voltage direct current) systems. It presents a dynamic approach to studying HVDC power stability, compared to the traditional quasi-static approach. Through dynamic time simulations and mathematical analysis, it shows that dynamic system modeling can impact the maximum power curve for HVDC systems. Specifically, including the dynamics of voltage control at the inverter AC system results in lower maximum available power than predicted by the quasi-static analysis that assumes a constant AC voltage source. The document examines the impact of different ramp rates for changes in DC current orders, and how the dynamic maximum power curve transitions between stable and unstable operating regions as the excitation system responds.
Thd minimization of modular multilevel converter with unequal dc valuesGhazal Falahi
Different modulation techniques used to control multilevel converters can be classified based on the selected converter topology and optimization goals. Among all proposed modulation methods low switching frequency modulation techniques are very popular for multilevel converters yet non-real time low switching frequency methods cannot be applied to multilevel converters with unequal or varying DC values because these modulation techniques rely on look up tables and the size of look up tables will be huge in this case. This paper proposes a new modular multilevel converter (MMC) structure with unequal DC values. Some well-known low switching frequency modulation techniques and the commonly used PWM based methods are compared and using the new low switching frequency modulation technique called minimal total harmonic distortion (THD) modulation for MMC with unequal DC values is proposed. The PSCAD simulation results show that the new converter topology with unequal DC values has much lower THD compared to the typical MMC. Modulation algorithm is implemented in digital signal processor (DSP) and controller hardware in the loop (CHIL) implementation in RTDS verifies the real-time performance of the algorithm.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
This document proposes and analyzes a reversible three-phase switching mode rectifier consisting of four active switches. It derives a closed-form pulse width modulation duty cycle control law to achieve sinusoidal input currents, controllable power factor, bidirectional power flow capability, and adjustable DC output voltage without using current sensors. The rectifier is modeled using state space averaging techniques and space vector representation. Both steady-state and small signal analyses are performed. Experimental results demonstrate the rectifier achieves the desired properties and bidirectional power flow. Guidelines for determining component parameters and controller gains are also described.
Control of modular multilevel converter based hvdc systems during asymmetrica...Ghazal Falahi
Modular multilevel converter (MMC) is a relatively new and promising topology for HVDC systems. HVDC systems should remain connected during grid faults and isolate the fault. This paper studies the dynamic performance of transformer-less MMC integrated HVDC systems during unbalanced conditions and asymmetrical grid faults. It proposes a new control technique to improve unbalanced system’s performance. The objective of the proposed controller is eliminating negative and zero sequence currents and to improve the overall performance. The controller calculates zero and negative sequence reference voltages and eliminates zero and negative sequence currents without using any current regulator. Therefore the controller is very fast and robust. The effectiveness of the proposed control technique has been validated by EMTDC /PSCAD simulations.
Simplified Space Vector Pulse Width Modulation Based on Switching Schemes wit...IJAAS Team
This paper presents a simplified control strategy of SVPWM with a three segment switching sequence and 7 segment switch frequency for high power multilevel inverter. In the proposed method, the inverter switching sequences are optimized for minimization of device switching sequence frequency and improvement of harmonic spectrum by using the three most derived switching states and one suitable redundant state for each space vector. The proposed 3-segment sequence is compared with conventional 7-segment sequence similar for five level Cascaded H-Bridge inverter with various values of switching frequencies including very low frequency. The output spectrum of the proposed sequence design shows the reduction of device switching frequency and states current and line voltage. THD this minimizing the filter size requirement of the inverter, employed in industrial applications. Where sinusoidal output voltage is required.
A Survey on Quality Changes in Positive, Negative and Combined Switching Stra...IJAPEJOURNAL
In this paper uses positive, negative and combined switching strategies for three phase ac/ac matrix converter .the author compares these strategies. The performance comparison of these three strategies is made under balanced operation. The simulation of three phase matrix converter feeding a three phase load was accomplished by means of the matlab/simulink software. After the simulation the comparison of the waveforms THD in three switching sequence is done. It must be mentioned that the duty cycle of the whole switches in the converter is according to Venturini switching algorithm
Modeling and Simulation of a Carrier-based PWM Voltage Source Inverter for a ...IAES-IJPEDS
The analysis of a carrier-based PWM two level voltage source inverter for a nine phase induction machine drive system is presented in this paper. Methods for generating zero-sequence signals during balanced and unbalanced condition are established. Simulation results for the analysis are presented. Two fault conditions involving the voltage source inverter and the nine-phase squirrel cage induction machine load are investigated. For the two fault scenarios considered, the effects on the performance characteristics of the induction machine load are highlighted. The simulation results obtained show that the two imbalance conditions considered result in substantial oscillations on the electromagnetic torque of the machine with attendant reduction in the torque rating. There is also large slip in the rotor speed.
Modified SVPWM Algorithm for 3-Level Inverter Fed DTC Induction Motor DriveIJPEDS-IAES
In this paper, a modified space vector pulse width modulation (MSVPWM)
algorithm is developed for 3-level inverter fed direct torque controlled
induction motor drive (DTC-IMD). MSVPWM algorithm simplifies
conventional space vector pulse width modulation (CSVPWM) algorithm for
multilevel inverter (MLI), whose complexity lies in sector/subsector/subsubsector
identification; which will commensurate with number of levels. In
the proposed algorithm sectors are identified as in two level inverter
and subsectors/sub-subsectors are identified by shifting the original reference
vector to sector 1 (S1). This is valid due to the fact that a three level space
vector plane is a composition of six two level space planes, and are
symmetrical with reference to six pivot states. Switching state/sequence
selection is also very important while dealing with SVPWM strategy for
MLI. In the proposed algorithm out of 27 available switching states apt
switching state is selected based on sector and subsector number, such that
voltage ripple is considerably less. To validate the proposed algorithm, it is
tested on a three level neutral point clamped (NPC) inverter fed DTC-IMD.
The performance of the MSVPWM algorithm is analyzed by comparing no
load stator current ripple of the three level DTC-IMD with two level
DTC-IMD. Significant reduction in steady state torque and flux ripple is
observed. Hence, reduced acoustic noise is a distinctive facet of the proposed
method.
In this paper, a new topology of Adaptive Hysteresis Band controller for Boost & Buck converter has been proposed, modeled and analyzed. The difficulties caused in Hysteresis Band (HB) controlled dc-dc converter have been eliminated using Adaptive Hysteresis Band (AHB) controller. This novel control topology can be able to maintain the switching frequency constant unlike HB controller. Thus the filter design for the converters will become easier with this controller. Again this control methodology is a robust one as it depends upon the system parameters where there was no possibility with HB controller. The Mathematical modeling of the controller is shown in this paper, further this has been simulated using Matlab /SIMULINK to generate pulse. The steady state analysis to find the parameters and the stability condition of the converter using the dynamic behavior is also portrayed in this paper. The simulation for a Boost and a Buck converter is also shown separately using AHB controller.
This document summarizes a research paper about a hybrid control algorithm for voltage regulation in DC-DC boost converters. The algorithm uses a hybrid automation representation to model the system's continuous and discrete dynamics. Guard conditions are derived to govern transitions between discrete states for both continuous conduction mode (CCM) and discontinuous conduction mode (DCM) operations. Simulation results show the algorithm effectively regulates output voltage under various load and disturbance conditions while smoothly transitioning between CCM and DCM. Experimental verification with a prototype converter circuit confirms the algorithm's effectiveness.
A Novel Three-Phase Three-Leg AC/AC Converter Using Nine IGBTSIJMER
This document summarizes a research paper that proposes a novel nine-switch AC/AC converter topology. The converter features sinusoidal inputs and outputs, unity input power factor, and reduced manufacturing cost due to fewer active switches compared to existing topologies. The operating principle and modulation schemes of the converter are described. Simulated loss analysis and experimental results from a 5-kVA prototype validate the proposed topology.
Design consideration of an mmc hvdc system based on 4500 v:4000a emitter turn...Ghazal Falahi
Excessive power loss is a major concern in high voltage and high power applications and is considered one of the main drawbacks of VSC-HVDC system when compared with traditional HVDC system based on thyristor technology. This is primarily caused by high switching loss associated with switching devices used in the VSC-HVDC. This issue can be largely addressed by using the emerging MMC-HVDC topology, which requires much lower switching frequency than traditional VSC-HVDC. Emitter turn-off thyristor (ETO) is one of the best high power switching devices packed with many advanced features. ETO thyristor based MMC-HVDC system is therefore an extremely attractive choice for ultra-high voltage and high power HVDCs. This paper discusses the operation principle of ETO based MMC-HVDC as well as its design and loss comparison with other solutions.
The document discusses how to customize and configure settings on a Windows desktop using the Control Panel. It lists settings that can be configured, including appearance and themes, network and internet connections, installed programs, sounds and audio, performance, printers, user accounts, date and time, accessibility options, and desktop shortcuts. It provides information on how to change the desktop appearance via the Control Panel's Themes, Desktop, Screen Saver, and Appearance tabs. It also covers how to set the desktop and background themes and use the Desktop Cleanup Wizard.
This document summarizes a study investigating multitasking with technology in academic settings. The study developed a conceptual model of factors that influence multitasking, including technology factors. It describes a survey and experiment methodology involving students in China and the US. The results showed that using technology while studying increases time and decreases accuracy. Multitasking reduces learning efficiency. Technology use during class also impacts information retention, though strong self-control may mitigate these effects. The study aims to further examine how technology-based factors influence multitasking and academic performance.
Investigation of the Common Mode Voltage for a Neutral-Point-Clamped Multilev...IJPEDS-IAES
The purpose of this paper is to provide a comprehensive Investigations and its control on the common mode Voltage (CMV) of the three-phase three-level neutral-point diode-clamped (NPC) multilevel inverter (MLI). A widespread space-vector pulse width modulation (SVPWM) technique to mitigate the perpetual problem of the NPC-MLI, the CMV, proposed. The proposed scheme is an effectual blend of nearest three vector (NTV) and selected three vector (STV) techniques. This scheme is capable to reduce the CMV without compromise the inverter output voltage and Total harmonics distraction (THD). CMV reduction achieved less than +Vdc/6 using the proposed vector selection procedure. The theoretical Investigations, the MATLAB software based computer simulation and Field Programmable Gate Array (FPGA) supported hardware corroboration have shown the superiority of the proposed technique over the conventional SVPWM schemes.
[9_CV] FCS-Model Predictive Control of Induction Motors feed by MultilLevel C...Nam Thanh
Ha Thanh Vo, Nam Thanh Hoang, Phuong Hoang Vu, Minh Trong Tran, Dich Quang Nguyen, “FCS-Model Predictive Control of Induction Motors feed by MultilLevel Casaded H-Bridge Inverter”, RCEEE-2018.
IOSR Journal of Electrical and Electronics Engineering(IOSR-JEEE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of electrical and electronics engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electrical and electronics engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
State-space averaged modeling and transfer function derivation of DC-DC boost...TELKOMNIKA JOURNAL
This paper presents dynamic analysis of a boost type DC-DC converter for high-brightness LED (HBLED) driving applications. The steady state operation in presence of all system parasitics has been discussed for continuous conduction mode (CCM). The state-space averaging, energy conservation principle and standard linearization are used to derive ac small signal control to inductor current open-loop transfer function of the converter. The derived transfer function can be further used in designing a robust feed-back control network for the system. In the end frequency and transient responses of the derived transfer function are obtained for a given set of component values, hence to provide a useful guide for control design engineers.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Low voltage ride through control of modular multilevel converter based hvdc s...Ghazal Falahi
Low Voltage Ride Through (LVRT) is an important grid requirement for Voltage Source Converter (VSC) based HVDC links. This paper studies the performance of the modular multilevel converter (MMC) VSC based HVDC systems during faults or voltage dips and proposes a new control strategy to improve the LVRT performance. The proposed algorithm controls the system to generate the required active and reactive powers that are calculated mathematically based on the ratings of the MMC-HVDC system and LVRT requirements. The injected active and reactive power values obey the LVRT guidelines and are adaptable to different grid codes. The mathematical calculations are presented and EMTDC/PSCAD simulation evaluates the performance of the proposed method.
A Review to AC Modeling and Transfer Function of DCDC ConvertersRadita Apriana
In this paper, AC modeling and small signal transfer function for DC-DC converters are
represented. The fundamentals governing the formulas are also reviewed. In DC-DC converters, the
output voltage must be kept constant, regardless of changes in the input voltage or in the effective load
resistance. Transfer function is the necessary knowledge to design a proper feedback control such as PID
control to regulate the output voltage as linear PID and PI controllers are usually designed for DC-DC
converters using standard frequency response techniques based on the small signal model of the
converter.
Impact of dynamic system modelling on the power stability of hvdc systemsIndra S Wahyudi
This document discusses the impact of dynamic system modeling on the power stability of HVDC (high-voltage direct current) systems. It presents a dynamic approach to studying HVDC power stability, compared to the traditional quasi-static approach. Through dynamic time simulations and mathematical analysis, it shows that dynamic system modeling can impact the maximum power curve for HVDC systems. Specifically, including the dynamics of voltage control at the inverter AC system results in lower maximum available power than predicted by the quasi-static analysis that assumes a constant AC voltage source. The document examines the impact of different ramp rates for changes in DC current orders, and how the dynamic maximum power curve transitions between stable and unstable operating regions as the excitation system responds.
Thd minimization of modular multilevel converter with unequal dc valuesGhazal Falahi
Different modulation techniques used to control multilevel converters can be classified based on the selected converter topology and optimization goals. Among all proposed modulation methods low switching frequency modulation techniques are very popular for multilevel converters yet non-real time low switching frequency methods cannot be applied to multilevel converters with unequal or varying DC values because these modulation techniques rely on look up tables and the size of look up tables will be huge in this case. This paper proposes a new modular multilevel converter (MMC) structure with unequal DC values. Some well-known low switching frequency modulation techniques and the commonly used PWM based methods are compared and using the new low switching frequency modulation technique called minimal total harmonic distortion (THD) modulation for MMC with unequal DC values is proposed. The PSCAD simulation results show that the new converter topology with unequal DC values has much lower THD compared to the typical MMC. Modulation algorithm is implemented in digital signal processor (DSP) and controller hardware in the loop (CHIL) implementation in RTDS verifies the real-time performance of the algorithm.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
This document proposes and analyzes a reversible three-phase switching mode rectifier consisting of four active switches. It derives a closed-form pulse width modulation duty cycle control law to achieve sinusoidal input currents, controllable power factor, bidirectional power flow capability, and adjustable DC output voltage without using current sensors. The rectifier is modeled using state space averaging techniques and space vector representation. Both steady-state and small signal analyses are performed. Experimental results demonstrate the rectifier achieves the desired properties and bidirectional power flow. Guidelines for determining component parameters and controller gains are also described.
Control of modular multilevel converter based hvdc systems during asymmetrica...Ghazal Falahi
Modular multilevel converter (MMC) is a relatively new and promising topology for HVDC systems. HVDC systems should remain connected during grid faults and isolate the fault. This paper studies the dynamic performance of transformer-less MMC integrated HVDC systems during unbalanced conditions and asymmetrical grid faults. It proposes a new control technique to improve unbalanced system’s performance. The objective of the proposed controller is eliminating negative and zero sequence currents and to improve the overall performance. The controller calculates zero and negative sequence reference voltages and eliminates zero and negative sequence currents without using any current regulator. Therefore the controller is very fast and robust. The effectiveness of the proposed control technique has been validated by EMTDC /PSCAD simulations.
Simplified Space Vector Pulse Width Modulation Based on Switching Schemes wit...IJAAS Team
This paper presents a simplified control strategy of SVPWM with a three segment switching sequence and 7 segment switch frequency for high power multilevel inverter. In the proposed method, the inverter switching sequences are optimized for minimization of device switching sequence frequency and improvement of harmonic spectrum by using the three most derived switching states and one suitable redundant state for each space vector. The proposed 3-segment sequence is compared with conventional 7-segment sequence similar for five level Cascaded H-Bridge inverter with various values of switching frequencies including very low frequency. The output spectrum of the proposed sequence design shows the reduction of device switching frequency and states current and line voltage. THD this minimizing the filter size requirement of the inverter, employed in industrial applications. Where sinusoidal output voltage is required.
A Survey on Quality Changes in Positive, Negative and Combined Switching Stra...IJAPEJOURNAL
In this paper uses positive, negative and combined switching strategies for three phase ac/ac matrix converter .the author compares these strategies. The performance comparison of these three strategies is made under balanced operation. The simulation of three phase matrix converter feeding a three phase load was accomplished by means of the matlab/simulink software. After the simulation the comparison of the waveforms THD in three switching sequence is done. It must be mentioned that the duty cycle of the whole switches in the converter is according to Venturini switching algorithm
Modeling and Simulation of a Carrier-based PWM Voltage Source Inverter for a ...IAES-IJPEDS
The analysis of a carrier-based PWM two level voltage source inverter for a nine phase induction machine drive system is presented in this paper. Methods for generating zero-sequence signals during balanced and unbalanced condition are established. Simulation results for the analysis are presented. Two fault conditions involving the voltage source inverter and the nine-phase squirrel cage induction machine load are investigated. For the two fault scenarios considered, the effects on the performance characteristics of the induction machine load are highlighted. The simulation results obtained show that the two imbalance conditions considered result in substantial oscillations on the electromagnetic torque of the machine with attendant reduction in the torque rating. There is also large slip in the rotor speed.
Modified SVPWM Algorithm for 3-Level Inverter Fed DTC Induction Motor DriveIJPEDS-IAES
In this paper, a modified space vector pulse width modulation (MSVPWM)
algorithm is developed for 3-level inverter fed direct torque controlled
induction motor drive (DTC-IMD). MSVPWM algorithm simplifies
conventional space vector pulse width modulation (CSVPWM) algorithm for
multilevel inverter (MLI), whose complexity lies in sector/subsector/subsubsector
identification; which will commensurate with number of levels. In
the proposed algorithm sectors are identified as in two level inverter
and subsectors/sub-subsectors are identified by shifting the original reference
vector to sector 1 (S1). This is valid due to the fact that a three level space
vector plane is a composition of six two level space planes, and are
symmetrical with reference to six pivot states. Switching state/sequence
selection is also very important while dealing with SVPWM strategy for
MLI. In the proposed algorithm out of 27 available switching states apt
switching state is selected based on sector and subsector number, such that
voltage ripple is considerably less. To validate the proposed algorithm, it is
tested on a three level neutral point clamped (NPC) inverter fed DTC-IMD.
The performance of the MSVPWM algorithm is analyzed by comparing no
load stator current ripple of the three level DTC-IMD with two level
DTC-IMD. Significant reduction in steady state torque and flux ripple is
observed. Hence, reduced acoustic noise is a distinctive facet of the proposed
method.
In this paper, a new topology of Adaptive Hysteresis Band controller for Boost & Buck converter has been proposed, modeled and analyzed. The difficulties caused in Hysteresis Band (HB) controlled dc-dc converter have been eliminated using Adaptive Hysteresis Band (AHB) controller. This novel control topology can be able to maintain the switching frequency constant unlike HB controller. Thus the filter design for the converters will become easier with this controller. Again this control methodology is a robust one as it depends upon the system parameters where there was no possibility with HB controller. The Mathematical modeling of the controller is shown in this paper, further this has been simulated using Matlab /SIMULINK to generate pulse. The steady state analysis to find the parameters and the stability condition of the converter using the dynamic behavior is also portrayed in this paper. The simulation for a Boost and a Buck converter is also shown separately using AHB controller.
This document summarizes a research paper about a hybrid control algorithm for voltage regulation in DC-DC boost converters. The algorithm uses a hybrid automation representation to model the system's continuous and discrete dynamics. Guard conditions are derived to govern transitions between discrete states for both continuous conduction mode (CCM) and discontinuous conduction mode (DCM) operations. Simulation results show the algorithm effectively regulates output voltage under various load and disturbance conditions while smoothly transitioning between CCM and DCM. Experimental verification with a prototype converter circuit confirms the algorithm's effectiveness.
A Novel Three-Phase Three-Leg AC/AC Converter Using Nine IGBTSIJMER
This document summarizes a research paper that proposes a novel nine-switch AC/AC converter topology. The converter features sinusoidal inputs and outputs, unity input power factor, and reduced manufacturing cost due to fewer active switches compared to existing topologies. The operating principle and modulation schemes of the converter are described. Simulated loss analysis and experimental results from a 5-kVA prototype validate the proposed topology.
Design consideration of an mmc hvdc system based on 4500 v:4000a emitter turn...Ghazal Falahi
Excessive power loss is a major concern in high voltage and high power applications and is considered one of the main drawbacks of VSC-HVDC system when compared with traditional HVDC system based on thyristor technology. This is primarily caused by high switching loss associated with switching devices used in the VSC-HVDC. This issue can be largely addressed by using the emerging MMC-HVDC topology, which requires much lower switching frequency than traditional VSC-HVDC. Emitter turn-off thyristor (ETO) is one of the best high power switching devices packed with many advanced features. ETO thyristor based MMC-HVDC system is therefore an extremely attractive choice for ultra-high voltage and high power HVDCs. This paper discusses the operation principle of ETO based MMC-HVDC as well as its design and loss comparison with other solutions.
The document discusses how to customize and configure settings on a Windows desktop using the Control Panel. It lists settings that can be configured, including appearance and themes, network and internet connections, installed programs, sounds and audio, performance, printers, user accounts, date and time, accessibility options, and desktop shortcuts. It provides information on how to change the desktop appearance via the Control Panel's Themes, Desktop, Screen Saver, and Appearance tabs. It also covers how to set the desktop and background themes and use the Desktop Cleanup Wizard.
This document summarizes a study investigating multitasking with technology in academic settings. The study developed a conceptual model of factors that influence multitasking, including technology factors. It describes a survey and experiment methodology involving students in China and the US. The results showed that using technology while studying increases time and decreases accuracy. Multitasking reduces learning efficiency. Technology use during class also impacts information retention, though strong self-control may mitigate these effects. The study aims to further examine how technology-based factors influence multitasking and academic performance.
This document provides guidance for job interview questions. It lists example questions and has the interviewee determine whether each question is appropriate for a first interview by writing "yes" or "no" and providing a reason. Acceptable first interview questions include why the position is open, daily responsibilities, and what the company does. Questions about pay, benefits, and expectations for the role are also suitable if asked respectfully. The document encourages preparing additional informed questions to ask to show interest in the role and company.
This document outlines the Chicago Youth Storage Initiative's plan to address the critical lack of storage for homeless youth in Chicago. It conducted research that found nearly 12,000 homeless youth in Chicago have very limited storage options. Its recommendations include piloting various storage models at different locations across Chicago over three phases from 2015-2017. This includes small-scale storage programs, a satellite storage site near a youth drop-in center, storage at schools and in the downtown area. It also proposes a cloud-based document storage pilot. The goal is to learn from different approaches to expand access to secure storage, which research found greatly impacts homeless youths' safety, well-being and ability to progress towards stability.
Reino Unido apuesta por el avance tecnológico y la innovación ferroviariaSemana Inglesa
El gobierno británico y más de 20 empresas están invirtiendo 6.11 millones de euros en un plan para promover la innovación tecnológica en la industria ferroviaria del Reino Unido. Los proyectos se centrarán en mejorar la seguridad, la eficiencia energética y la experiencia del pasajero, y también explorarán oportunidades de colaboración con la industria automotriz. El objetivo es desarrollar nuevas tecnologías, crear un mercado de exportación ferroviaria y acelerar el crecimiento de la
This document provides an overview of how to enhance presentations with multimedia effects in PowerPoint. It discusses how to add text and graphics to slides, format text, change slide layouts, use slide masters, add transitions between slides, and print handouts. The objectives are to learn how to insert pictures and other graphics, format text, change the slide layout, use slide masters to apply consistent formatting, create transitions between slides, change the slide order, and print accompanying materials.
This document provides an overview of editing and formatting documents in Word. It covers topics such as deleting and inserting text, undoing and redoing actions, cutting/copying/pasting text, finding and replacing text, and formatting text with fonts, alignments, and other styles. The objectives are to learn how to edit text, format documents, check spelling and count words, and preview documents before printing. Key terms related to editing and formatting are also defined.
This document provides an overview of computer hardware components and concepts. It discusses the central processing unit, motherboard, memory (RAM and ROM), data representation, input/output devices, and the basic functions of computer hardware including storing and processing data. The objectives are to identify system components, explain how the CPU works, differentiate memory types, and describe common input/output devices and storage.
This document contains information about PVR Technology, including their head office location, website, email, and phone number. It then lists 20 project titles related to power electronics and renewable energy systems. The projects cover topics like power quality improvement, single-stage converters, grid-connected inverters, maximum power point tracking, stand-alone energy sources, power factor correction, resonant inverters, DC-DC converters, AC-DC converters, filters, and induction heating applications.
Done by Group: Wakrag_rock8
School: Al Wakra Independent School for Girls
Composites Module: Students discover what composite materials are and test them to learn their advantages over pure materials. Finally, at the end of the workshop, they design new composite materials.
This project: Fighting corrosion in oil pipeline.
This presentation discusses small hydropower (SHP) projects for community development. SHP refers to hydroelectric power projects that are 10MW or less. The key benefits of SHP include clean, reliable electricity production while avoiding large environmental and social impacts. SHP technologies are also simple to deploy and maintain, making them suitable for rural communities. Case studies from Pakistan and China show how SHP projects have provided electricity access, economic opportunities, and environmental benefits when implemented with community participation, engagement, and capacity building. Lessons from successful SHP projects emphasize the importance of involving local stakeholders and ensuring financial sustainability.
SALIENT FEATURES OF GRID-CONNECTED PHOTOVOLTAIC SYSTEM AND ITS IMPACT ON POWE...Editor IJMTER
Solar energy is available to the world for free of cost from millions of years and it is a
basic energy source to the mankind. It is also one of largest energy source to the mankind. PV
systems are a relative new technology. The operational experience with PV systems itself is at an
acceptable high level and today’s installed PV systems are of a good quality and are able to operate
without any problems for many years. The price level of the PV modules and the Balance of System
costs (inverter included) have decreased significantly. This energy is available all around the world
in large quantity. When this energy is collected by the solar PV cells it is in the small power with the
D.C. supply, which is not compatible with the existing grid in the world. There is an inverter and the
converter stage comes before this energy can used. Grid interactive PV systems can vary
substantially in size.
This document summarizes the results of a questionnaire given in September 2015. It provides the percentage of correct answers for 30 multiple choice questions across four categories: European history, Greek history, art, and politics. The percentages of correct answers for each question range widely, from 0% to 67.78% correct.
Comparison analysis of chattering in smooth sliding mode controlled DC-DC buc...journalBEEI
This paper presents a comparative analysis of chattering in sliding mode controlled DC-DC buck converter for chattering suppression using constant plus proportional reaching law and proposed reaching laws. A smooth SMC is used for chattering suppression in buck converter. The different switching functions are used in proposed reaching laws and constant plus proportional reaching law applied to SMC buck converter, the tan hyperbolic reaching law, sigmoid reaching law and constant plus proportional rate reaching law. The proposed method tan hyperbolic gives less switching loss among the reaching laws and stable output voltage. Inturn, performance of the buck converter increases, tanhyperbolic reaching law is more sensitive to matched, mismatched disturbance and parameter uncertainties. Loading conditions are also applied to the buck converter to measure the disturbances and parametric variations. The results are verified by MATLAB/Simulink.
This document proposes a digital state feedback control method for current control of parallel DC-DC converters. It derives the digital state feedback controller structures for both continuous and discrete time domains using a pole placement technique. This allows precise current sharing among converter modules while meeting performance specifications. It provides examples applying this control scheme to a bidirectional converter for a 42V/14V automotive system in continuous time and a parallel buck converter in discrete time. Both examples are implemented on a DSP to verify the proposed control method.
Small Signal Modelling of a Buck Converter using State Space Averaging for Ma...paperpublications3
This document presents a small-signal model of a buck converter operating in continuous conduction mode (CCM) with a magnetic load. It uses state-space averaging methodology to derive dynamic equations for the converter. The model is linearized around an operating point to obtain a linear time-invariant small-signal model. Transfer functions are derived in the s-domain to characterize the frequency response of the power stage dynamics. The model is validated through simulations in MATLAB using illustrative system parameters. It can be used to design robust closed-loop controllers for DC-DC buck regulators.
Performance comparison of different control strategies for the regulation of ...IJECEIAES
This document compares three control strategies - voltage mode control (VMC), current mode control (CMC), and sliding mode control (SMC) - for regulating the output voltage of a negative output super-lift Luo converter (NOSLC). Simulation results show that SMC provides the best performance with fast response, low ripple, and ability to maintain a constant output voltage under changing load conditions. SMC also outperforms VMC and CMC in terms of tracking the reference voltage, settling time, rise time, and overshoot. The document concludes that SMC is the most effective control method for the NOSLC.
1) The document discusses different control strategies for DSTATCOM (distribution static synchronous compensator), including Synchronous Reference Frame (SRF) methods, to mitigate voltage sags and compensate reactive power.
2) It analyzes the SRF method, SRF without phase locked loop (PLL), and a modified SRF method through mathematical modeling and MATLAB simulation.
3) The comparison of results from the different control strategies indicates that SRF provides effective compensation of voltage sags and reactive power under steady state conditions.
In this paper, a three-phase load connected to a NPC three-level inverter is presented. To generate gate signals for the multilevel inverter, two commands are developed and compared: the phase disposition pulse width modulation (PDPWM) and the space vector pulse width modulation (SVPWM). DC supply is provided by photovoltaic cells. Boost converter controls the power transfer from photovoltaic generator. Due to nonlinear I-V characteristics of photovoltaic cells, a maximum power point tracking algorithm is adopted to maximize the output power, the nonlinear controller (sliding mode) is developed and simulated. To verify the effectivnesse of the introdueced controller, it is compared with the fuzzy logic controller. Matlab-simulink is used for simulation, analysis and interpretation the results of these controllers.
Input-output linearization of DC-DC converter with discrete sliding mode fuz...IJECEIAES
The major thrust of the paper is on designing a fuzzy logic approach has been combined with a well-known robust technique discrete sliding mode control (DSMC) to develop a new strategy for discrete sliding mode fuzzy control (DSMFC) in direct current (DC-DC) converter. Proposed scheme requires human expertise in the design of the rule base and is inherently stable. It also overcomes the limitation of DSMC, which requires bounds of uncertainty to be known for development of a DSMC control law. The scheme is also applicable to higher order systems unlike model following fuzzy control, where formation of rule base becomes difficult with rise in number of error and error derivative inputs. In this paper the linearization of input-output performance is carried out by the DSMFC algorithm for boost converter. The DSMFC strategy minimizes the chattering problem faced by the DSMC. The simulated performance of a discrete sliding mode fuzzy controller is studied and the results are investigated.
Enhanced sliding mode controller performance in DC-DC buck converter using a ...journalBEEI
This paper presents an enhanced sliding mode controller (SMC) operation, chattering analysis and loading conditions of the SMC DC-DC buck converter. Sliding mode portion, chattering attenuation are analyzed by using a conventional and proposed reaching law in buck converter. A proposed tan hyperbolic reaching law (THRL) is originated to be useful in terms of chattering mitigation and fast convergence. The major drawback of the conventional reaching law viz, it bypasses the main portion of the sliding mode portion to ensure fast reaching. It causes more chattering, more time to reach the steady state on the switching surface. The most significant improvement of SMC is that it guarantees strengthening the sliding mode phase. The proposed tan hyperbolic reaching law is being hit here during an exponential adjustment so that the attributes of it, covers complete sliding mode portion, chattering mitigation and fast reaching time. In turn, cause fewer switching loss in the buck converter. Even external disturbances and uncertainty of the system occurs. The loading conditions are applied to proposed tan hyperbolic reaching law and analyzed. Simulation analysis conducted by MATLAB/Simulink.
Design and Simulation Analysis of Sliding Mode Controller for DC-DC Cuk Conve...IJMREMJournal
Due to compact size and fast dynamic response DC-DC converters are used to a great extent. DC-DC Cuk converter has switching transients which leads to switching losses and harmonics generation. With a linear controller like Proportional integral derivative (PID), the transients and oscillations under supply and load variations cannot be controlled. So, it becomes necessary to use a nonlinear controller to make transient performance of the converter stable increase its efficiency. A great advantage of this controller includes, it’s based on large signal model of DC to DC converters hence its stability is not bounded by the size of the interpretations around the working point. In this research work, simulation model of cuk converter with sliding mode controller is developed and tested using MATLAB SIMULINK. Effectiveness of proposed sliding mode controller for cuk converter is proved from simulation results.
Design and Simulation Analysis of Sliding Mode Controller for DC-DC Cuk Conve...IJMREMJournal
Due to compact size and fast dynamic response DC-DC converters are used to a great extent. DC-DC Cuk
converter has switching transients which leads to switching losses and harmonics generation. With a linear
controller like Proportional integral derivative (PID), the transients and oscillations under supply and load
variations cannot be controlled. So, it becomes necessary to use a nonlinear controller to make transient
performance of the converter stable increase its efficiency. A great advantage of this controller includes, it’s
based on large signal model of DC to DC converters hence its stability is not bounded by the size of the
interpretations around the working point. In this research work, simulation model of cuk converter with sliding
mode controller is developed and tested using MATLAB SIMULINK. Effectiveness of proposed sliding mode
controller for cuk converter is proved from simulation results.
Compensator Based Performance Enhancement Strategy for a SIQO Buck ConverterIAES-IJPEDS
This paper attempts to design lag and lag-lead compensators for improving the performance of a Single Inductor Quad Output (SIQO) dc-dc buck converter in terms of time domain and frequency domain specifications. It develops the state space averaged model to find the duty ratio of the desired output voltages at steady state. The exercise arrives at the transfer function model from the state space averaged model through the use of its lumped small signal equivalent circuit which allows analyzing the performance of the system in frequency and time domains.The responses are derived in the MATLAB/Simulink® using discrete components incorporating compensators of the converter. The hardware results obtained using Data Acquisition Module DT9834® interfaced to MATLAB/Simulink® and prototype model establish the performance of the compensator based converter and further emphasize its ability to minimize the ripples over a range of operating loads.
Average Phase-Leg Technique on Coupling Impedance Impact Modular Inverter Par...IJMTST Journal
This document discusses control methods for parallel-connected modular multilevel converters (parallel-MMCs). It proposes controlling the individual submodule voltages and average phase voltages to balance capacitor voltages across the MMCs. It also proposes using resonant controllers to mitigate circulating currents within and between the parallel-MMCs. The document discusses fault-tolerant control schemes to address open and short circuit switch faults without redundant hardware. Simulations and experimental results validate the control strategy's ability to balance voltages and attenuate circulating currents under normal and fault conditions.
In present days of electrical industries, adjustable speed controlled induction
motor drives are very common due to its versatile features. For the speed control of induction
motor, variable frequency sources are the heart of such drives. To attain variable frequency
and variable voltage supply a power electronics device; single phase matrix converter is
proposed.
In this paper, the single phase matrix converter is modeled in MATLAB Simulink
environment; controlled with sinusoidal pulse width modulation technique, control scheme is
implemented in a Xilinx system generator environment and interfaced with power circuit in
MATLAB Simulink. Analyses this SPMC with different type of loads in both frequency step
up and step down modes. Based on simulation results, this converter is suitable for variable
frequency power supplies, varying load conditions and variable speed electrical drives.
FPGA control is best suitable for controlling a circuit like SPMC, consists of more
controlled elements to attain fast operation.
Finite State Predictive Current and Common Mode Voltage Control of a Seven-ph...IAES-IJPEDS
The paper illustrates finite set predictive current control (FSPC) along with
common mode voltage control of a seven-phase voltage source inverter
(VSI). The current and common mode voltage (CMV) controls are done
considering a finite set of control actions. The space vector model of a sevenphase
voltage source inverter produces 27 = 128 space voltage vectors, with
126 active and two zero vectors. Out of 126 space vectors 112 are distinct
and 14 are redundant vectors. To control the current and the common mode
voltage, specific set of space vectors are chosen that minimizes the
magnitude of the CMV and makes it a dc signal and simultaneously track the
reference current. Hence no common mode current can flow. Three sets of
space vectors are used for switching actuation, in one case only 15 vectors
are used (14 active and one zero), in second case 14 vectors are used,
followed by use of 8 space vectors (7 large and one zero) and finally 7 large
vectors are employed. Optimal algorithm is employed to find the vector
which minimizes the chosen cost function. The effect of selecting the cost
function, the number of space vectors on current tracking and common mode
voltage is investigated and reported. The developed technique is tested for
RL load using simulation and experimental approaches.
Modified Chattering Free Sliding Mode Control of DC MotorIJMER
This document discusses the design of a modified sliding mode controller for position control of a DC motor. It begins with an introduction to PID controllers and sliding mode controllers. It then provides the mathematical modeling of a DC motor and describes the conventional sliding mode control approach. It discusses some issues with chattering in sliding mode control and proposes a modified approach using a boundary layer. The document also describes tuning a PID controller using the Ziegler-Nichols method. It aims to compare the performance of the modified sliding mode controller to PID controllers for position control of a DC motor.
This document summarizes the use of sliding mode control for DC-DC converters. It discusses that sliding mode control is a nonlinear control technique that can handle the nonlinearity and uncertainties of DC-DC converters. It provides the basic principles of sliding mode control, which includes designing a sliding surface, and control laws to meet the conditions of hitting, existence and stability. The document reviews several past studies that applied sliding mode control to DC-DC converters and achieved benefits like robustness, elimination of static errors and fast transient response.
This document summarizes a research paper that proposes a new control technique for a Doubly Fed Induction Generator (DFG) used in variable speed wind turbines. The technique uses a nonlinear sliding mode control approach with an exponential reaching law (ERL) to control the active and reactive powers generated by the wind turbine. Simulation results show that this sliding mode control with ERL is more robust and improves power quality and stability compared to traditional sliding mode control approaches. It reduces chattering phenomenon while also accelerating the system response for better tracking of the desired control objectives.
Model Predictive Current Control of a Seven-phase Voltage Source Inverteridescitation
The paper elaborate finite set model based predictive
current control of a seven-phase voltage source inverter. The
current control is carried out considering a finite set of control
actions. The space vector model of a seven-phase voltage source
inverter (VSI) yields 27 = 128 space voltage vectors, with 126
active and two zero vectors. The control method described in
this paper discard some switching states from the whole set
and employs reduced number of switching states to track the
commanded current. Three sets of space vectors are used for
switching actuation, in one case only 15 vectors are used (14
active and one zero), in second case 29 vectors are used (28
active and one zero) and finally 43 vectors (42 active and one
zero) are employed. Optimal algorithm is employed to find
the vector which minimizes the chosen cost function. The
effect of selecting the cost function, the number of space
vectors and the sampling time is investigated and reported.
The developed technique is tested for RL load using simulation
and experimental approaches.
1. The document proposes a continuous sliding mode control strategy for a voltage source inverter to address issues from load variations and current sensor faults.
2. A novel boundary-based saturation function is designed where the boundary thickness depends on the PWM signal generation, reducing chattering while maintaining robustness against load changes.
3. A particle swarm optimization-based modified observer is used to estimate inductor current without current sensors, optimizing observer gains to minimize estimation errors.
Digital Voltage Control of DC-DC Boost ConverterIJERA Editor
The need for digital control for faster communication between power stage module & system controllers is increased with requirement of load complexity. The requirements also include stability of power module with the parametric variation. This paper presents a digital control of a dc-dc boost converter under nominal parameter conditions. The system controller has been verified in both frequency response as well as MATLAB-Simulink under nominal & parametric varying condition. The modeling of converter has been illustrated using state-space averaging technique. Direct digital design method is equipped to design the controller in frequency response to yield constant load voltage. The characteristic of load voltage before & after parametric variation is shown.
Similar to Adaptive terminal sliding mode control strategy for dc–dc buck converters (20)
An optimal general type-2 fuzzy controller for Urban Traffic NetworkISA Interchange
This document presents an optimal general type-2 fuzzy controller (OGT2FC) for controlling traffic signal scheduling and phase succession to minimize wait times and average queue length. The OGT2FC uses a combination of general type-2 fuzzy logic sets and the Modified Backtracking Search Algorithm (MBSA) to optimize the membership function parameters. Simulation results show the OGT2FC performs better than conventional type-1 fuzzy controllers in regulating urban traffic flow.
Embedded intelligent adaptive PI controller for an electromechanical systemISA Interchange
In this study, an intelligent adaptive controller approach using the interval type-2 fuzzy neural network (IT2FNN) is presented. The proposed controller consists of a lower level proportional - integral (PI) controller, which is the main controller and an upper level IT2FNN which tuning on-line the parameters of a PI controller. The proposed adaptive PI controller based on IT2FNN (API-IT2FNN) is implemented practically using the Arduino DUE kit for controlling the speed of a nonlinear DC motor-generator system. The parameters of the IT2FNN are tuned on-line using back-propagation algorithm. The Lyapunov theorem is used to derive the stability and convergence of the IT2FNN. The obtained experimental results, which are compared with other controllers, demonstrate that the proposed API-IT2FNN is able to improve the system response over a wide range of system uncertainties.
State of charge estimation of lithium-ion batteries using fractional order sl...ISA Interchange
This paper presents a state of charge (SOC) estimation method based on fractional order sliding mode observer (SMO) for lithium-ion batteries. A fractional order RC equivalent circuit model (FORCECM) is firstly constructed to describe the charging and discharging dynamic characteristics of the battery. Then, based on the differential equations of the FORCECM, fractional order SMOs for SOC, polarization voltage and terminal voltage estimation are designed. After that, convergence of the proposed observers is analyzed by Lyapunov’s stability theory method. The framework of the designed observer system is simple and easy to implement. The SMOs can overcome the uncertainties of parameters, modeling and measurement errors, and present good robustness. Simulation results show that the presented estima- tion method is effective, and the designed observers have good performance.
Fractional order PID for tracking control of a parallel robotic manipulator t...ISA Interchange
This paper presents the tracking control for a robotic manipulator type delta employing fractional order PID controllers with computed torque control strategy. It is contrasted with an integer order PID controller with computed torque control strategy. The mechanical structure, kinematics and dynamic models of the delta robot are descripted. A SOLIDWORKS/MSC-ADAMS/MATLAB co-simulation model of the delta robot is built and employed for the stages of identification, design, and validation of control strategies. Identification of the dynamic model of the robot is performed using the least squares algorithm. A linearized model of the robotic system is obtained employing the computed torque control strategy resulting in a decoupled double integrating system. From the linearized model of the delta robot, fractional order PID and integer order PID controllers are designed, analyzing the dynamical behavior for many evaluation trajectories. Controllers robustness is evaluated against external disturbances employing performance indexes for the joint and spatial error, applied torque in the joints and trajectory tracking. Results show that fractional order PID with the computed torque control strategy has a robust performance and active disturbance rejection when it is applied to parallel robotic manipulators on tracking tasks.
Fuzzy logic for plant-wide control of biological wastewater treatment process...ISA Interchange
The application of control strategies is increasingly used in wastewater treatment plants with the aim of improving effluent quality and reducing operating costs. Due to concerns about the progressive growth of greenhouse gas emissions (GHG), these are also currently being evaluated in wastewater treatment plants. The present article proposes a fuzzy controller for plant-wide control of the biological wastewater treatment process. Its design is based on 14 inputs and 6 outputs in order to reduce GHG emissions, nutrient concentration in the effluent and operational costs. The article explains and shows the effect of each one of the inputs and outputs of the fuzzy controller, as well as the relationship between them. Benchmark Simulation Model no 2 Gas is used for testing the proposed control strategy. The results of simulation results show that the fuzzy controller is able to reduce GHG emissions while improving, at the same time, the common criteria of effluent quality and operational costs.
Design and implementation of a control structure for quality products in a cr...ISA Interchange
In recent years, interest for petrochemical processes has been increasing, especially in refinement area. However, the high variability in the dynamic characteristics present in the atmospheric distillation column poses a challenge to obtain quality products. To improve distillates quality in spite of the changes in the input crude oil composition, this paper details a new design of a control strategy in a conventional crude oil distillation plant defined using formal interaction analysis tools. The process dynamic and its control are simulated on Aspen HYSYS dynamic environment under real operating conditions. The simulation results are compared against a typical control strategy commonly used in crude oil atmospheric distillation columns.
Model based PI power system stabilizer design for damping low frequency oscil...ISA Interchange
This paper explores a two-level control strategy by blending a local controller with a centralized controller for the low frequency oscillations in a power system. The proposed control scheme provides stabilization of local modes using a local controller and minimizes the effect of inter-connection of sub-systems performance through a centralized control. For designing the local controllers in the form of proportional-integral power system stabilizer (PI-PSS), a simple and straight forward frequency domain direct synthesis method is considered that works on use of a suitable reference model which is based on the desired requirements. Several examples both on one machine infinite bus and multi-machine systems taken from the literature are illustrated to show the efficacy of the proposed PI-PSS. The effective damping of the systems is found to be increased remarkably which is reflected in the time-responses; even unstable operation has been stabilized with improved damping after applying the proposed controller. The proposed controllers give remarkable improvement in damping the oscillations in all the illustrations considered here and as for example, the value of damping factor has been increased from 0.0217 to 0.666 in Example 1. The simulation results obtained by the proposed control strategy are favorably compared with some controllers prevalent in the literature.
A comparison of a novel robust decentralized control strategy and MPC for ind...ISA Interchange
This document summarizes a research article that compares a novel decentralized control strategy based on override control to a model predictive controller (MPC) for controlling an industrial high purity methanol distillation column. Both controllers were able to maintain tight product purity and high recovery specifications under disturbances. The MPC provided tighter control of product purity but used more energy, while the proposed override control provided tighter recovery control and had lower costs. An economic analysis showed the optimal choice depends on factors like energy costs.
Fault detection of feed water treatment process using PCA-WD with parameter o...ISA Interchange
This research article proposes a new fault detection algorithm called PCA-WD that combines wavelet denoising (WD) with principal component analysis (PCA) to improve fault detection performance for feed water treatment processes (FWTP). The algorithm is applied to operational data from a FWTP sustaining two 1000 MW coal-fired power plants. Parameter selection for the PCA-WD algorithm is formulated as an optimization problem solved using particle swarm optimization to determine optimal parameters automatically rather than relying on individual experience. Results show that WD effectively reduces noise in PCA statistics, improving fault detection. The optimized PCA-WD algorithm outperforms classical PCA and a related method in detecting various faults in the FWTP data.
Model-based adaptive sliding mode control of the subcritical boiler-turbine s...ISA Interchange
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Adaptive terminal sliding mode control strategy for dc–dc buck converters
1. Adaptive terminal sliding-mode control strategy for DC–DC buck converters
Hasan Komurcugil n
Computer Engineering Department, Eastern Mediterranean University, Gazi Magusa, North Cyprus, via Mersin 10, Turkey
a r t i c l e i n f o
Article history:
Received 2 January 2012
Received in revised form
22 June 2012
Accepted 17 July 2012
Available online 9 August 2012
This paper was recommended for publica-
tion by Jeff Pieper
Keywords:
Sliding-mode control
Terminal sliding-mode control
Finite time convergence
DC–DC buck converter
a b s t r a c t
This paper presents an adaptive terminal sliding mode control (ATSMC) strategy for DC–DC buck
converters. The idea behind this strategy is to use the terminal sliding mode control (TSMC) approach to
assure finite time convergence of the output voltage error to the equilibrium point and integrate an
adaptive law to the TSMC strategy so as to achieve a dynamic sliding line during the load variations. In
addition, the influence of the controller parameters on the performance of closed-loop system is
investigated. It is observed that the start up response of the output voltage becomes faster with
increasing value of the fractional power used in the sliding function. On the other hand, the transient
response of the output voltage, caused by the step change in the load, becomes faster with decreasing
the value of the fractional power. Therefore, the value of fractional power is to be chosen to make a
compromise between start up and transient responses of the converter. Performance of the proposed
ATSMC strategy has been tested through computer simulations and experiments. The simulation
results of the proposed ATSMC strategy are compared with the conventional SMC and TSMC strategies.
It is shown that the ATSMC exhibits a considerable improvement in terms of a faster output voltage
response during load changes.
& 2012 ISA. Published by Elsevier Ltd. All rights reserved.
1. Introduction
DC–DC converters are power electronics devices which are
widely used in many applications including DC motor drives,
communication equipments, and power supplies for personal
computers [1]. The buck type DC–DC converters are used in
applications where the required output voltage is smaller than
the input voltage. Since buck converters are inherently nonlinear
and time-varying systems due to their switching operation, the
design of high performance control strategy is usually a challen-
ging issue. The main objective of the control strategy is to ensure
system stability in arbitrary operating condition with good
dynamic response in terms of rejection of input voltage changes,
load variations and parameter uncertainties. Nonlinear control
strategies are deemed to be better candidates in DC–DC converter
applications than other linear feedback controllers. Various non-
linear control strategies for the buck converters have been
proposed to achieve these objectives [2–15]. Among these control
strategies, the sliding mode control (SMC) has received much
attention due to its major advantages such as guaranteed stabi-
lity, robustness against parameter variations, fast dynamic
response and simplicity in implementation [2–4,6–8,10,11,14].
The design of an SMC consists of two steps: design of a sliding
surface and design of a control law [8]. Once a suitable sliding
surface and a suitable control law are designed, the system states
can be forced to move toward the sliding surface and slide on the
surface until the equilibrium (origin) point is reached.
The SMC introduced in [3] has the advantages of separate
switching action and the sliding action, but the computation
requirement of the inductor’s current reference function increases
the complexity of the controller. A simple and systematic
approach to the design of practical SMC has been presented
in [6]. The adaptive feedforward and feedback based SMC strategy
introduced in [7] has the advantages of adjusting the hysteresis
width according to the input voltage change and the sliding
coefficient according to the load change. The indirect SMC via
double integral sliding surface strategy introduced in [10] reduces
the steady-state error in the output voltage at the expense of
having additional two states in the sliding surface function. In
[13], a time-optimal based SMC has been introduced aiming to
improve the output voltage regulation of the converter subjected
to any disturbance. The SMC strategy in [14] is based on the
alternative model of the buck converter with bilinear terms.
In most SMC strategies proposed for the buck converters so far,
the most commonly used sliding surface is the linear sliding
surface which is based on linear combination of the system states
by using an appropriate time-invariant coefficient (commonly
termed as l). The use of such coefficient makes the sliding line
static during load variations resulting in a poor transient response
in the output voltage. Despite the transient response can be made
Contents lists available at SciVerse ScienceDirect
journal homepage: www.elsevier.com/locate/isatrans
ISA Transactions
0019-0578/$ - see front matter & 2012 ISA. Published by Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.isatra.2012.07.005
n
Tel.: þ90 392 6301363; fax: þ90 392 3650711.
E-mail address: hasan.komurcugil@emu.edu.tr
ISA Transactions 51 (2012) 673–681
2. faster by utilizing a larger valued coefficient in the linear sliding
surface function, the system states cannot converge to the
equilibrium point in finite time. Different from the conventional
SMC, the terminal sliding mode control (TSMC) has a nonlinear
sliding surface function [18]. The nonlinear sliding surface func-
tion has the ability to provide a terminal convergence (finite-time
convergence) of the output voltage error from an initial point to
the equilibrium point.
In this paper, an adaptive terminal sliding mode control
(ATSMC) strategy is proposed for the DC–DC buck converters.
The idea behind this strategy is to use the TSMC for assuring finite
time convergence of the output voltage error to the equilibrium
point and integrate an adaptive law to the TSMC strategy so as to
make the sliding line dynamic during the load variations. Differ-
ent from the linear sliding surface function in conventional SMC,
the output voltage error (x1) in the nonlinear sliding surface
function has a fractional power (commonly termed as g) in the
TSMC. Therefore, the convergence time of the output voltage
depends on the parameters l and g. The influence of the fractional
power on the start up and the transient responses of the output
voltage, the inductor current and the state trajectory is investi-
gated. Since the performance of the TSMC with fixed l (i.e. static
sliding line) during load variations does not exhibit the desired
response, an adaptive terminal sliding mode control (ATSMC)
strategy has been employed in which sliding line is made
dynamic by making l load dependent. Finally, simulation and
experimental results are presented for verification.
The rest of this paper is organized as follows. In Section 2, the
dynamic model of buck converter is given. Section 3 reviews the
conventional sliding mode control method for the buck converter.
In Section 4, the proposed adaptive terminal sliding mode control
was described for the buck converter. In Section 5, the simulation
and experimental results are presented and compared with the
conventional sliding mode control method. Finally, the conclu-
sions are addressed in Section 6.
2. Dynamic model of the DC-DC buck converter
Fig. 1 shows a DC–DC buck converter. It consists of a DC input
voltage source (Vin), a controlled switch (Sw), a diode (D), a filter
inductor (L), filter capacitor (C), and a load resistor (R). Equations
describing the operation of the converter can be written for the
switching conditions ON and OFF, respectively, as
diL
dt
¼
1
L
ðVinÀvoÞ ð1Þ
dvo
dt
¼
1
C
iLÀ
vo
R
ð2Þ
and
diL
dt
¼ À
vo
L
ð3Þ
dvo
dt
¼
1
C
iLÀ
vo
R
ð4Þ
Combining (1), (2), (3) and (4) gives
diL
dt
¼
1
L
ðuVinÀvoÞ ð5Þ
dvo
dt
¼
1
C
iLÀ
vo
R
ð6Þ
where u is the control input which takes 1 for the ON state of the
switch and 0 for the OFF state. Let us define the output voltage
error x1 and its derivative (rate of change of the output voltage
error) as
x1 ¼ voÀVref ð7Þ
x2 ¼ _x1 ¼ _voÀ _V ref ¼ _vo ð8Þ
where _x1 denotes the derivative of x1, and Vref is the DC reference
for the output voltage.
By taking the time derivative of (6), the voltage error x1 and
the rate of change of voltage error x2 dynamics can be expressed
as
_x1 ¼ x2 ð9Þ
_x2 ¼ À
x2
RC
Ào2
ox1 þo2
oðuVinÀVref Þ ð10Þ
where o2
o ¼ 1=LC.
3. Conventional sliding mode control
Let a linear sliding surface function S be expressed as
S ¼ lx1 þx2, l40 ð11Þ
where l is a time-invariant sliding coefficient. The dynamic
behavior of (11) without external disturbance on the sliding
surface is [16]
S ¼ lx1 þ _x1 ¼ 0 ð12Þ
In the phase-plane (x1 Àx2 plane), S¼0 represents a line, called
sliding line, passing through the origin with a slope equal to
m¼ Àl. The sliding mode (S¼0) is described by the following
first-order equation:
_x1 ¼ Àlx1 ð13Þ
During the sliding mode, the output voltage error is expressed
as
x1ðtÞ ¼ x1ð0ÞeÀlt
ð14Þ
It should be noted that l must be positive for achieving the
system stability. This fact can be easily verified by substituting a
negative l quantity into (14) which results in x1(t) moving away
from zero.
In general, the SMC exhibits two modes: the reaching mode
and the sliding mode. While in the reaching mode, a reaching
control law is applied to drive the system states to the sliding line
rapidly. When the system states are on the sliding line, the system
is said to be in the sliding mode in which an equivalent control
law is applied to drive the system states, along the sliding line, to
the origin. When the state trajectory is above the sliding line, u¼0
(Sw is OFF) must be applied so as to direct the trajectory towards
the sliding line. Conversely, when the state trajectory is below the
sliding line, u¼1 (Sw is ON) must be applied so that the trajectory
is directed towards the sliding line. The control law that adopts
+
C
L
D
+
SW
– –
RvoVin
iL
iRiC
Fig. 1. DC–DC buck converter.
H. Komurcugil / ISA Transactions 51 (2012) 673–681674
3. such switching can be defined as
u ¼
1
2
ð1ÀsignðSÞÞ ¼
1 if So0
0 if S40
ð15Þ
However, direct implementation of this control law causes the
converter to operate at an uncontrollable infinite switching
frequency which is not desired in practice. Hence, it is required
to suppress the switching frequency into an acceptable range. In
order to accomplish this, a hysteresis modulation (HM) method
employing a hysteresis band with suitable switching boundaries
around the switching line is used as [6]
u ¼
1 when SoÀh
0 when S4h
(
ð16Þ
where h is the hysteresis bandwidth. When S4h, switch Sw will
turn OFF. Conversely, it will turn ON when So Àh. Such operation
limits the operating frequency of the switch.
When the system is in the sliding mode, the robustness of the
converter will be guaranteed and the dynamics of the converter
will depend on l. In order to ensure that the movement of the
error variables is maintained on the sliding line, the following
existence condition must be satisfied
S_S o0 ð17Þ
The time derivative of (11) can be written as
_S ¼ l_x1 þ _x2 ð18Þ
Substituting (9) and (10) into (18) yields the following
inequalities [6]:
l1 ¼ lÀ
1
RC
x2 þo2
oðVinÀVref Àx1Þ40 for So0 when u ¼ 1
ð19Þ
l2 ¼ lÀ
1
RC
x2Ào2
oðVref þx1Þo0 for S40 when u ¼ 0 ð20Þ
Equations l1 ¼0 and l2 ¼0 define two lines in the phase-plane
with the same slope passing through points P1 ¼(Vin ÀVref,0) and
P2 ¼(ÀVref,0) on the x1 axis, respectively. The slope of these lines
is given by
m1 ¼ m2 ¼
o2
o
ðlÀ1=RCÞ
ð21Þ
The regions of existence of the sliding mode for different l values
(l41/RC and lo1/RC) are depicted in Fig. 2. It is clear that the
sliding line splits the phase-plane into two regions. In each region, the
state trajectory is directed towards the sliding line by an appropriate
switching action. The sliding mode occurs only on the portion of the
sliding line, S¼0, that covers both regions. This portion is within S1
and S2. It can be seen from Fig. 2(a) that the large l value causes a
reduction of sliding mode existence region. When the state trajectory
hits the sliding line in a point outside the sliding mode existence
region S1S2, it overshoots the sliding line which leads to an overshoot
in the output voltage. The x2 intercepts of the lines l1 and l2 are
Y1 ¼ o2
oðVref ÀVinÞ=ðlÀ1=RCÞ and Y2 ¼ o2
oVref =ðlÀ1=RCÞ, respec-
tively. On the other hand, when l is small, the state trajectory hits
the sliding line in a point inside the sliding mode existence region
S1S2, and it moves toward the origin as seen in Fig. 2(b). Note that
when lo1/RC, the slope of these lines is negative which changes the
x2 intercepts of the lines l1 and l2 as Y2 ¼ o2
oVref =ðlÀ1=RCÞ and
Y1 ¼ o2
oðVref ÀVinÞ=ðlÀ1=RCÞ, respectively. It is evident from (14)
and Fig. 2 that the dynamic response of the buck converter depends
on the value of l. In order to ensure that l is large enough for fast
dynamic response and low enough to retain a large existence region,
it has been proposed in [6] to set l as
l ¼
1
RC
ð22Þ
However, despite the dynamic response can be made faster by
utilizing a large l in the sliding surface function, the system states
still cannot converge to the equilibrium point in finite time.
4. Adaptive terminal sliding mode control for buck converter
Let a nonlinear sliding surface function for the buck converter
system defined in (9) and (10) be defined as
Sn ¼ lx
g
1 þ _x1 ð23Þ
where l40, and 0o(g¼q/p)o1 where p and q are positive odd
integers satisfying p4q. When the system is in the terminal
sliding mode (Sn ¼0), its dynamics can be determined by the
following nonlinear differential equation:
_x1 ¼ Àlx
g
1 ð24Þ
Note that Eq. (24) reduces to _x1 ¼ Àlx1 for g¼1, which is the
form of conventional SMC. It has been shown in [17] that x1 ¼0 is
the terminal attractor of the system defined in (1). The term
‘‘terminal’’ is referred to the equilibrium which can be reached in
finite time. Note that Eq. (24) can also be written as
dt ¼ À
dx1
lx
g
1
ð25Þ
Taking integral of both sides of (25) and evaluating the
resulting equation on the closed interval (x1(0)a0, x1(ts)¼0)
Fig. 2. Regions of existence of the sliding mode for: (a) l41/RC and (b) lo1/RC.
H. Komurcugil / ISA Transactions 51 (2012) 673–681 675
8. 1Àg
lð1ÀgÞ
ð26Þ
Eq. (26) means that when the system enters to the terminal
sliding mode at t¼tr with initial condition x1(0)a0, the system
state x1 converges to x1(ts)¼0 in finite time and stay there for
tZts. In other words, when the state trajectory hits the sliding
surface at time tr, the system state cannot leave the sliding line
meaning that the state trajectory will belong to the sliding line for
tZtr. However, it is obvious from (26) that the convergence time,
ts, still depends on the parameters g and l. Therefore, these
parameters must be carefully selected to ensure the desired
response.
4.1. Selection of g
When x1 is near the equilibrium point (9x19o1), the fractional
power g¼q/p leads to 9x
g
1949x19. In such a case, the system state
with the nonlinear term x
g
1 converges toward equilibrium point
more faster than the linear term x1. Especially, when g is too small
near the equilibrium point, the state trajectory moves toward the
equilibrium point as if it follows the bottom of a bowl rather than
following a straight line which results in a distorted inductor
current during load variations. In order to show the influence of
parameter g on the dynamic performance of the TSMC, a sample
simulation study has been performed by using the parameters
Vin ¼10 V, Vref¼5 V, L¼1 mH, C¼1000 mF, R¼10 O, and
l¼1/RC¼100.
Fig. 3 shows the start-up responses of the output voltage, the
inductor current and the state trajectories of the converter with
different g values. It is clear from Fig. 3(a) and (b) that the output
voltage and the inductor current responses become faster with
increasing the value of g. The main reason of this comes from the
fact that the slope of the sliding line with g4 ¼0.8182 is greater
than all other sliding line slopes as shown in Fig. 3(c) resulting in
a faster response as pointed out in (14). All the state trajectories
start from the point ÀVref¼ À5 V on the x1 axis (as vo(0)¼0 V),
which agrees well with the intersection point of l2 shown in Fig. 2.
When the trajectory reaches the sliding line, it starts to slide
along it by making a zigzag movement. However, when it
approaches the equilibrium point (9x19o1) it changes its direc-
tion and makes a movement similar to the bottom of a bowl. This
direction change is inversely proportional with the g value. This
means that any change in the direction becomes smaller when g
values get larger. This fact is clearly visible in Fig. 3(c).
Fig. 4 shows the responses of the output voltage and the
inductor current for a step change in R from 10 O to 2 O which
are obtained by the SMC method with g¼1 and the TSMC method
with different g values. Unlike the start up case, it is interesting to
note that the output voltage and the inductor current responses
become faster with decreasing the value of g. Therefore, g value is
to be chosen to make a compromise between start up and transient
responses of the converter. It is well known that the current
dynamics is faster than the voltage dynamics. Since the transient
responses of the inductor current for different g values are super-
imposed, then only two responses are presented in Fig. 4(b).
4.2. Selection of l
It has been discussed before that l is usually set to 1/RC for a
good performance of the system. However, the TSMC with
constant l cannot exhibit the same transient performance when
the converter is subjected to a load change. The main reason of
this performance degrade is due to the static sliding line
irrespective of the operating point change caused by the load
change. It is clear from (21) that l is inversely proportional to R.
Therefore, instead of fixing it at l¼1/RC with nominal load
resistance, its value should be adaptively changed when a load
change occurs. However, it is not possible to measure the load
resistance directly in a practical implementation. Therefore, the
instantaneous value of the load resistance can be estimated by
measuring the output voltage across and the current passing
through the load resistance as
^R ¼
vo
iR
ð27Þ
0
Fig. 3. Simulated start up responses of the output voltage, the inductor current,
and the state trajectories obtained by the TSMC method with different g values:
(a) vo, (b) iL, and (c) state trajectories.
H. Komurcugil / ISA Transactions 51 (2012) 673–681676
9. Since the value of R is used to vary l in the TSMC, such control
results in an adaptive terminal sliding mode control (ATSMC). The
adaptation comes from the time variation of the l term in the
nonlinear terminal sliding mode. The block diagram of the DC-DC
buck converter with the proposed ATSMC method is depicted in
Fig. 5.
4.3. Stability analysis and sliding mode dynamics
The sufficient condition for the existence of the terminal
sliding mode is given by
Sn
_Sn o0 ð28Þ
If a control input is designed which ensures (28), then the
system will be forced towards the sliding surface and remains on
it until origin is reached asymptotically. Now, let
VðtÞ ¼ 1
2S2
n ð29Þ
be a Lyapunov function candidate for the system described in (9)
and (10). The time derivative of (29) can be written as
_V ðtÞ ¼ Sn
_Sn o0 ð30Þ
Differentiating (23) with respect to time and using in (30), one
can obtain
_V ðtÞ ¼ Sn
_Sn ¼ Snðlgx
gÀ1
1 x2 þ _x2Þo0 ð31Þ
Substituting (10) into (31) and solving for u gives
ueq ¼
1
o2
oVin
x2
RC
þo2
oðVref þx1ÞÀlgx
gÀ1
1 x2
ð32Þ
Eq. (32) is the equivalent control needed to keep the system
motion on the sliding surface under ideal terminal sliding mode.
However, the equivalent control may not be able to move the
system states from reaching mode to the sliding mode. Therefore,
an additional control action known as the switching control is
needed that should be applied to the system together with the
equivalent control. Hence, the total control input can be written
as
u ¼
1
o2
oVin
x2
RC
þo2
oðVref þx1ÞÀlgx
gÀ1
1 x2ÀKsignðSnÞ
ð33Þ
Fig. 4. Simulated transient responses of the output voltage and the inductor
current due to a step change in R from 10 O to 2 O obtained by the SMC and the
TSMC methods with different g values: (a) vo and (b) iL.
Fig. 5. Block diagram of the DC–DC buck converter with the proposed ATSMC method.
Fig. 7. Switching frequency for different input voltages.
Fig. 6. Sliding function with hysteresis band.
H. Komurcugil / ISA Transactions 51 (2012) 673–681 677
10. where K denotes the switching control gain. Rewriting (10) as
_x2 ¼ À
x2
RC
Ào2
ox1 þo2
oðuVinÀVref ÞþdðtÞ ð34Þ
and substituting (33) into (34) and the resulting equation into
(31) yields
_V ðtÞ ¼ Sn
_Sn ¼ ðÀKSnsignðSnÞþSndðtÞÞo0 ð35Þ
where satisfies K49d(t)9, and d(t) denotes the disturbances
caused by parametric variations in the system. Clearly, for both
Sn 40 and Sn o0, _V ðtÞ is always negative for all values of the
system states which means that the system has a finite-time
convergent stability irrespective of the disturbances in the sys-
tem. This means that the ATSMC offers a strong robustness
against the variations in input voltage and reference output
voltage during the sliding mode. It should be noted that the
ATSMC method does not offer a strategy to estimate the domain
of attraction around the equilibrium point. Although, it is very
difficult to estimate the domain of attraction analytically, there
are some recent works that try to estimate it [19,20].
Substituting (9) and (10) into _Sn ¼ lgx
gÀ1
1
_x1 þ _x2 and using
Eq. (15) give the following inequalities that satisfy the existence
condition given in (28):
lgx
gÀ1
1 x2À
x2
RC
þo2
oðVinÀVref Àx1Þ40 for So0 when u ¼ 1 ð36Þ
lgx
gÀ1
1 x2À
x2
RC
Ào2
oðVref þx1Þo0 for S40 when u ¼ 0 ð37Þ
Eqs. (36) and (37) describe the sliding mode dynamics of the
closed-loop system.Fig. 8. Switching frequency for different output voltage references.
SMC
SMC
TSMC
ATSMC
TSMC
and
ATSMC
1.66ms
TSMC
and
ATSMC
ATSMC
State trajectory due
to the step change
State trajectory due
to the start up
State trajectory due
to the step change
State trajectory due
to the start up
Fig. 9. Simulated start up and transient responses (due to a step change in R from 10 O to 2 O) of the output voltage, and the state trajectory obtained by the SMC, the
TSMC and the ATSMC methods with g¼0.2: (a) vo, (b) magnified response of vo and iL obtained by ATSMC, (c) state trajectory obtained by the SMC and (d) state trajectory
obtained by the TSMC and the ATSMC.
H. Komurcugil / ISA Transactions 51 (2012) 673–681678
11. 4.4. Switching frequency
The frequency at which a practical buck converter can be
switched is limited by such factors as hysteresis bandwidth, input
voltage, output voltage, and LC filter. Therefore, an estimate of the
switching frequency would be helpful in designing the system.
Consider a typical trajectory of the sliding function with hyster-
esis band depicted in Fig. 6. From the geometry of Fig. 6, we can
write the ON and OFF periods of switch Sw as
TON ¼
2h
_S
þ
n
ð38Þ
TOFF ¼
À2h
_S
À
n
ð39Þ
where _S
þ
n and _S
À
n are the time derivatives of Sn for ON and OFF
states of the switch Sw, respectively. The time derivative of (23)
can be written as
_Sn ¼ lgx
gÀ1
1 x2À
x2
RC
þo2
oðuVinÀVref Àx1Þ ð40Þ
Assuming that the errors x1 and x2 are negligible in the steady-
state, Eqs. (38) and (39) can be written as
TON ¼
2h
o2
oðVinÀVref Þ
ð41Þ
TOFF ¼
2h
o2
oVref
ð42Þ
Hence, the expression for the switching frequency can be
obtained as
fs ¼
1
TON þTOFF
¼
o2
oVref
2h
1À
Vref
Vin
ð43Þ
Clearly, the switching frequency is inversely proportional to
the hysteresis bandwidth (h). The hysteresis bandwidth is chosen
so as to obtain a suitable switching frequency given in (43).
In order to investigate the influence of other parameters, the
converter’s switching frequency is computed by using (43) with
L¼1 mH, C¼1000 mF, and h¼100 for different input voltages and
different output voltage references. Figs. 7 and 8 show the
switching frequency (fs) for different input voltages (Vin) at
Vref¼5 V and different output voltage references (Vref) at
Vin ¼10 V, respectively. It can be seen that fs increases with
increasing Vin. As for output voltage reference variation, it is
observed that fs decreases while Vref increases. Note that by
changing the hysteresis bandwidth, it is possible to keep the
switching frequency constant against input voltage variation at
the expense of additional control complexity requirements.
5. Simulation and experimental results
In order to demonstrate the performance of the proposed
ATSMC strategy, the DC–DC buck converter system has been
tested by simulations and experiments. Simulations are carried
out using Simulink of Matlab with a step size of 2 ms. Experi-
mental results were obtained from a hardware setup constructed
in the laboratory. The parameters of the system are Vin ¼10 V,
Vref¼5 V, h¼80, L¼1 mH, and C¼1000 mF.
Fig. 9 shows the simulated start up and transient responses of
the output voltage and the state trajectories obtained by SMC,
TSMC and ATSMC strategies. The value of g used in the TSMC and
Fig. 10. Experimental responses of the output voltage and the inductor current for
start up and a step change in R from 10 O to 2 O: (a) start up and (b) step change.
Fig. 11. Experimental responses of the inductor current and the control input for
the step change in the load resistance from 10 O to 2 O: (a) responses of iL and u,
(b) magnified responses of iL and u for R¼10 O and (c) magnified responses of iL
and u for R¼2 O.
H. Komurcugil / ISA Transactions 51 (2012) 673–681 679
12. ATSMC strategies was 0.2 (q¼1 and p¼5). The load resistor was
set to R¼10 O during the start up. The transient responses are
due to a step change in R from 10 O to 2 O at t¼0.08 s. It is
obvious from Fig. 9(a) that the output voltage tracks its reference
successfully in all cases. The start up response of the output
voltage obtained by the SMC is faster than that of obtained by the
TSMC and ATSMC. Conversely, the transient responses of the
output voltage obtained by the TSMC and ATSMC are faster than
that of obtained by the SMC. The ATSMC offers the fastest
transient response which shows that the controller acts very fast
in correcting the output voltage. Note that the TSMC and ATSMC
exhibit exactly the same response from the start up until the step
change occurs in the load resistance. The main reason of this
comes from the fact that both methods employ the same l value
until the load change takes place. After the load change occurs,
while the TSMC continues to operate with the same l value, the
ATSMC makes use of the adaptively computed l value. The
magnified response of the output voltage, due to the step change
in the load, together with the inductor current obtained by the
ATSMC method is shown in Fig. 9(b). The output voltage takes
approximately 1.66 ms to track its reference. Fig. 9(c) and (d)
shows the state trajectories that correspond to the simulation
case shown in Fig. 9(a). Note that both trajectories start from the
point ÀVref¼ À5 V on the x1 axis, since vo(0)¼0 V. In the start up,
the slope of the sliding line in Fig. 9(d) is smaller than that of in
Fig. 9(c). However, after the load is changed, the slope of the
sliding line in Fig. 9(d) becomes greater than that of in
Fig. 9(c) leading to a faster response in the output voltage.
Experimental results were also obtained for testing the dynamic
performance of the proposed ATSMC method under step changes in
the load, in the input voltage and in the reference output voltage.
Fig. 10 shows the experimental responses of the output voltage and
the inductor current for the start up and the step change in the load
resistance from 10 O to 2 O. It can be seen from Fig. 10(a) that the
start up responses of the output voltage and inductor current are in
good agreement with the simulation results shown in Fig. 9(a) and
Fig. 3(b), respectively. Fig. 10(b) shows the experimental result that
corresponds to the simulation result presented in Fig. 9(b). It took
about 2 ms for the controller to correct the output voltage at 5 V. The
small discrepancy between the simulation and experimental results
comes from the component tolerances, and non-ideal effects (e.g.,
finite time delay) in the practical system which cause the output
voltage to make slower transitions.
Fig. 11 shows the response of the inductor current and the
control input for the step change in the load resistance from 10 O
to 2 O. Fig. 11(a) shows the magnified response of the inductor
current that is shown in Fig. 10(b) and the control input. The
magnified responses of the control input for R¼10 O and R¼2 O
are shown in Fig. 11(b) and (c), respectively. The switching
frequency of the converter is measured approximately as fs ¼
1/64 ms¼15.625 kHz. Note that one can obtain the same result by
using (43) with Vin¼10 V, Vref¼5 V, h¼80, L¼1 mH, and
C¼1000 mF. This shows that the switching frequency computa-
tion is fairly accurate.
Fig. 12 shows the response of the output voltage for step
changes in the reference output voltage (Vref) from 5 V to 7 V and
the input voltage (Vin) from 10 V to 8 V. It is clear from
Fig. 12(a) that the output voltage tracks its reference faster and
successfully. Also, as shown in Fig. 12(b), the output voltage is
almost not affected for the step change in the input voltage. The
results presented in Fig. 12 show that the ATSMC method is very
robust against input and reference voltage variations.
Fig. 13 shows the state trajectory in the steady-state.
6. Conclusions
An adaptive terminal sliding mode control (ATSMC) strategy,
which assures finite time convergence of the output voltage error
to the equilibrium point, has been proposed for DC–DC buck
converters. The influence of the controller parameters on the perfor-
mance of closed-loop system is investigated. It is observed that the
start up response of the output voltage becomes faster when the
value of the fractional power is increased. On the other hand, the
transient response of the output voltage caused by the step change in
the load resistance becomes faster when the value of the fractional
power is decreased. Therefore, one should consider a compromise
between start up and transient responses when choosing the value of
the fractional power. Simulation and experimental results show that
the ATSMC strategy, as compared to the conventional SMC and TSMC
strategies, is quite successful in obtaining very fast output voltage
responses to load disturbances.
Fig. 12. Experimental responses of the output voltage for step changes in the
reference output voltage and the input voltage: (a) response of vo for a step
change in Vref from 5 V to 7 V and (b) response of vo for a step change in Vin from
10 V to 8 V.
Fig. 13. Experimental state trajectory in the steady-state.
H. Komurcugil / ISA Transactions 51 (2012) 673–681680
13. References
[1] Rashid M. Power electronics: circuits, devices, and applications. Prentice-
Hall; 1993.
[2] Nguyen VM, Lee CQ. Tracking control of buck converter using sliding-mode
with adaptive hysteresis. In: Proceedings of the IEEE power electronics
specialists conference; 1995. p. 1086–93.
[3] Nguyen VM, Lee CQ. Indirect implementations of sliding-mode control law in
buck-type converters. In: Proceedings of the IEEE applied power electronics
conference; 1996. p. 111–5.
[4] Perry AG, Feng G, Liu YF, Sen PC. A new sliding mode like control method for
buck converter. In: Proceedings of the IEEE power electronics specialists
conference; 2004. p. 3688–93.
[5] Leung KKS, Chung HSH. Derivation of a second-order switching surface in the
boundary control of buck converters. IEEE Power Electronics Letters 2004;2(2)
63–7.
[6] Tan SC, Lai YM, Cheung MKH, Tse CK. On the practical design of a sliding
mode voltage controlled buck converter. IEEE Transactions on Power Electro-
nics 2005;20(2):425–37.
[7] Tan SC, Lai YM, Tse CK, Cheung MKH. Adaptive feedforward and feedback
control schemes for sliding mode controlled power converters. IEEE Transac-
tions on Power Electronics 2006;21(1):182–92.
[8] Tan SC, Lai YM, Tse CK. A unified approach to the design of PWM-based
sliding-mode voltage controllers for basic DC–DC converters in continuous
conduction mode. IEEE Transactions on Circuits and Systems Part I
2006;53(8):1816–27.
[9] Leung KKS, Chung HSH. A comparative study of boundary control with first-
and second-order switching surfaces for buck converters operating in DCM.
IEEE Transactions on Power Electronics 2007;22(4):1196–209.
[10] Tan SC, Lai YM, Tse CK. Indirect sliding mode control of power converters via
double integral sliding surface. IEEE Transactions on Power Electronics
2008;23(2):600–11.
[11] Tan SC, Lai YM, Tse CK. General design issues of sliding-mode controllers in
DC–DC converters. IEEE Transactions on Industrial Electronics 2008;55(3):
1160–74.
[12] Babazadeh A, Maksimovic D. Hybrid digital adaptive control for fast transient
response in synchronous buck DC–DC converters. IEEE Transactions on
Power Electronics 2009;24(11):2625–38.
[13] Jafarian MJ, Nazarzadeh J. Time-optimal sliding-mode control for multi-
quadrant buck converters. IET Power Electronics 2011;4(1):143–50.
[14] Tsai JF, Chen YP. Sliding mode control and stability analysis of buck DC–DC
converter. International Journal of Electronics 2007;94(3):209–22.
[15] Truntic M, Milanovic M, Jezernik K. Discrete-event switching control for buck
converter based on the FPGA. Control Engineering Practice 2011;19:502–12.
[16] Eker I. Second-order sliding mode control with experimental application. ISA
Transactions 2010;49:394–405.
[17] Zak M. Terminal attractors for addressable memory in neural network.
Physics Letters A 1988;133(1–2):18–22.
[18] Man ZH, Paplinski AP, Wu HR. A robust MIMO terminal sliding mode control
scheme for rigid robotic manipulator. IEEE Transactions on Automatic
Control 1994;39(12):2464–9.
[19] Aguilar-Ibanez C, Sira-Ramirez H. A linear differential flatness approach to
controlling the Furuta pendulum. IMA Journal of Mathematical Control and
Information 2007;24(1):31–45.
[20] Aguilar-Ibanez C, Sira-Ramirez H, Suarez-Castanon MS, Martinez-Navarro E,
Moreno-Armendariz MA. The trajectory tracking problem for an unmanned
four-rotor system: flatness-based approach. International Journal of Control
2012;85(1):69–77.
H. Komurcugil / ISA Transactions 51 (2012) 673–681 681