This document summarizes a project to design a novel damper with constant velocity over a range of input torques. Multiple design concepts were considered including using a DC motor with sliding mode control (SMC) to achieve a vertical torque-speed relationship. A prototype was tested and found to match the performance predicted by a Simulink model. The testing validated the SMC concept. Recommendations include further optimizing parameters like motor constants in the model and exploring applications based on known motor specifications and control system response times.
A Unified Control Strategy for Three-phase Inverter in Distributed GenerationAsoka Technologies
This paper presents a unified control strategy that enables both islanded and grid-tied operation of three-phase inverter in distributed generation (DG), with no need for switching between two corresponding controllers or critical islanding detection. The proposed control strategy composes of an inner inductor current loop, and a novel voltage loop in the synchronous reference frame (SRF). The inverter is regulated as a current source just by the inner inductor current loop in grid-tied operation, and the voltage controller is automatically activated to regulate the load voltage upon the occurrence of islanding. Furthermore, the waveforms of the grid current in grid-tied mode and the load voltage in islanding mode are distorted under nonlinear local load with the conventional strategy. And this issue is addressed by proposing a unified load current feed forward in the paper. Additionally, the paper presents the detailed analysis and the parameter design of the control strategy. Finally, the effectiveness of the proposed control strategy is validated by the simulation and experimental results.
This paper presents the modeling and simulation of
a magnetorheological damper based semiactive suspension using
variable structure controllers. Passive suspension systems tend to
limit the trade-off between passenger comfort and road handling.
But Semiactive suspensions can reduce this trade-off margin and
dynamically respond to the damping requirements. Active
suspensions provide the best response since they can add damping
force in any direction, but are prone to higher power consumption.
Semiactive suspensions just change the damping coefficient by
simply applying a control voltage as and when required. The
performance of three controllers- sigma 1, sigma 2 and sigma 3,
are measured and analyzed using nine parameters using peak,
root mean square and normalized approaches. The road
excitations considered are a single road hump and random road
disturbance. The control system is applied to a 2-degree of
freedom quarter car model of a passenger car. A modified BoucWen
model of MR damper is used to cater to the system responses
at near zero velocities. The performance of these controllers is
superior to the uncontrolled case, which is similar to passive
suspension system. Sigma 3 controller is superior to the
uncontrolled system by 63% while sigma 1 and sigma 2 are
superior by 53% when it comes to peak suspension deflection for
a random road disturbance. Both sigma 2 and sigma 3 controllers
are better in terms of performance. The validation of the
semiactive suspension leads to selection of sigma 2 controller over
sigma 3 controller because of its simplicity in implementation in
real-time systems.
Power quality improvement in distribution network using DSTATCOM with battery...Asoka Technologies
The distribution static compensator (DSTATCOM) provides fast control of active and reactive powers to enable load compensation, harmonics current elimination, voltage flicker mitigation, voltage and frequency regulation. This paper presents power quality improvement technique in the presence of grid disturbances and wind energy penetration using DSTATCOM with battery energy storage system. DSTATCOM control is provided based on synchronous reference frame theory. A modified IEEE 13 bus test feeder with DSTATCOM and wind generator is used for the study. Power quality events during grid disturbances such as feeder tripping and re-closing, voltage sag, swell and load switching have been studied in association with DSTATCOM. The power quality disturbances due to wind generator outage, synchronization and wind speed variations have also been investigated. The study has been carried out using MATLAB/SIMULINK and the simulation results are compared with real time results obtained by the use of real time digital simulator (RTDS) for validating the effectiveness of proposed methodology. The proposed method has been proved to be effective in improvement of power quality with all disturbances stated above.
Sensor less speed control of pmsm using svpwm technique based on mras method ...Asoka Technologies
The permanent magnet synchronous motor (PMSM) has emerged as an alternative to the induction motor because of the reduced size, high torque to current ratio, higher efficiency and power factor in many applications. Space Vector Pulse Width Modulation (SVPWM) technique is applied to the PMSM to obtain speed and current responses with the variation in load. This paper analysis the structure and equations of PMSM, SVPWM and voltage space vector process. The Model Reference Adaptive System (MRAS) is also studied. The PI controller uses from estimated speed feedback for the speed senseless control of PMSM based on SVPWM with MRAS. The control scheme is simulated in the MATLAB/Simulink software environment. The simulation result shows that the speed of rotor is estimated with high precision and response is considerable fast. The whole control system is effective, feasible and simple.
Zero voltage-switching sinusoidal pulse width modulation method for three-pha...Asoka Technologies
A Zero-Voltage-Switching (ZVS) sinusoidal pulse width modulation (SPWM) method for three-phase four-wire inverter is proposed in order to achieve higher efficiency and power density. With the proposed modulation scheme, the ZVS operation of all switches including the main switches and the auxiliary switch can be realized. Besides, all seven switches operate at a fixed frequency. The ZVS SPWM scheme is introduced by considering the various combinations of the polarities in three-phase filter inductors currents and analysis of operating stages is presented. ZVS condition of the ZVS SPWM scheme is derived and discussions of ZVS condition for typical three-phase loads are also provided. In addition, the resonant parameters design and loss analysis are briefly investigated. Finally the proposed ZVS SPWM scheme is verified on a 10 kW inverter prototype with SiC MOSFET devices.
Maximum power extraction from wind energy system based on fuzzy logic controlAsoka Technologies
This paper proposes a variable speed control scheme for grid-connected wind energy conversion system (WECS) using permanent magnet synchronous generator (PMSG). The control algorithm tracks the maximum power for wind speeds below rated speed of wind turbines and ensures the power will not go over the rated power for wind speeds over the rated value. The control algorithm employs fuzzy logic controller (FLC) to effectively do this target. The wind turbine is connected to the grid via back-to-back PWM-VSC. Two effective computer simulation packages (PSIM and Simulink) are used to carry out the simulation effectively. The control system has two controllers for generator side and grid side converters. The main function of the generator side controller is to track the maximum power through controlling the rotational speed of the wind turbine using FLC. In the grid side converter, active and reactive power control has been achieved by controlling q-axis and d-axis current components, respectively. The d-axis current is set at zero for unity power factor and the q-axis current is controlled to deliver the power flowing from the dc-link to the electric utility grid.
Dual-function PV-ECS integrated to 3P4W distribution grid using 3M-PLL contro...Asoka Technologies
This study proposes a single-stage solar photovoltaic energy conversion system (PV-ECS) integrated to a three phase four-wire (3P4W) distribution grid with dual-function capabilities, i.e. active power transfer and power quality (PQ) enhancement at the point of interaction (PoI). The PV-ECS system comprises of a solar photovoltaic array and a voltage source inverter (VSI), supplying active power (during daytime) to the distribution grid and connected single-phase and three-phase loads. Apart from transfer of power, the system also improves the PQ at the PoI by compensating reactive power and neutral current, attenuating harmonics, correcting power factor and balancing grid currents. During night, the VSI acts as a shunt active power filter mitigating PQ issues, thereby increasing the device utilisation factor. A three-phase magnitude-phase locked loop (3M-PLL) method is utilised to extract and estimate fundamental term of load currents and an incremental conductance algorithm is applied for maximum power point tracking. To demonstrate its effectiveness, the system is modelled and its performance is simulated on MATLAB and experiments are performed on a developed prototype in the laboratory.
A Unified Control Strategy for Three-phase Inverter in Distributed GenerationAsoka Technologies
This paper presents a unified control strategy that enables both islanded and grid-tied operation of three-phase inverter in distributed generation (DG), with no need for switching between two corresponding controllers or critical islanding detection. The proposed control strategy composes of an inner inductor current loop, and a novel voltage loop in the synchronous reference frame (SRF). The inverter is regulated as a current source just by the inner inductor current loop in grid-tied operation, and the voltage controller is automatically activated to regulate the load voltage upon the occurrence of islanding. Furthermore, the waveforms of the grid current in grid-tied mode and the load voltage in islanding mode are distorted under nonlinear local load with the conventional strategy. And this issue is addressed by proposing a unified load current feed forward in the paper. Additionally, the paper presents the detailed analysis and the parameter design of the control strategy. Finally, the effectiveness of the proposed control strategy is validated by the simulation and experimental results.
This paper presents the modeling and simulation of
a magnetorheological damper based semiactive suspension using
variable structure controllers. Passive suspension systems tend to
limit the trade-off between passenger comfort and road handling.
But Semiactive suspensions can reduce this trade-off margin and
dynamically respond to the damping requirements. Active
suspensions provide the best response since they can add damping
force in any direction, but are prone to higher power consumption.
Semiactive suspensions just change the damping coefficient by
simply applying a control voltage as and when required. The
performance of three controllers- sigma 1, sigma 2 and sigma 3,
are measured and analyzed using nine parameters using peak,
root mean square and normalized approaches. The road
excitations considered are a single road hump and random road
disturbance. The control system is applied to a 2-degree of
freedom quarter car model of a passenger car. A modified BoucWen
model of MR damper is used to cater to the system responses
at near zero velocities. The performance of these controllers is
superior to the uncontrolled case, which is similar to passive
suspension system. Sigma 3 controller is superior to the
uncontrolled system by 63% while sigma 1 and sigma 2 are
superior by 53% when it comes to peak suspension deflection for
a random road disturbance. Both sigma 2 and sigma 3 controllers
are better in terms of performance. The validation of the
semiactive suspension leads to selection of sigma 2 controller over
sigma 3 controller because of its simplicity in implementation in
real-time systems.
Power quality improvement in distribution network using DSTATCOM with battery...Asoka Technologies
The distribution static compensator (DSTATCOM) provides fast control of active and reactive powers to enable load compensation, harmonics current elimination, voltage flicker mitigation, voltage and frequency regulation. This paper presents power quality improvement technique in the presence of grid disturbances and wind energy penetration using DSTATCOM with battery energy storage system. DSTATCOM control is provided based on synchronous reference frame theory. A modified IEEE 13 bus test feeder with DSTATCOM and wind generator is used for the study. Power quality events during grid disturbances such as feeder tripping and re-closing, voltage sag, swell and load switching have been studied in association with DSTATCOM. The power quality disturbances due to wind generator outage, synchronization and wind speed variations have also been investigated. The study has been carried out using MATLAB/SIMULINK and the simulation results are compared with real time results obtained by the use of real time digital simulator (RTDS) for validating the effectiveness of proposed methodology. The proposed method has been proved to be effective in improvement of power quality with all disturbances stated above.
Sensor less speed control of pmsm using svpwm technique based on mras method ...Asoka Technologies
The permanent magnet synchronous motor (PMSM) has emerged as an alternative to the induction motor because of the reduced size, high torque to current ratio, higher efficiency and power factor in many applications. Space Vector Pulse Width Modulation (SVPWM) technique is applied to the PMSM to obtain speed and current responses with the variation in load. This paper analysis the structure and equations of PMSM, SVPWM and voltage space vector process. The Model Reference Adaptive System (MRAS) is also studied. The PI controller uses from estimated speed feedback for the speed senseless control of PMSM based on SVPWM with MRAS. The control scheme is simulated in the MATLAB/Simulink software environment. The simulation result shows that the speed of rotor is estimated with high precision and response is considerable fast. The whole control system is effective, feasible and simple.
Zero voltage-switching sinusoidal pulse width modulation method for three-pha...Asoka Technologies
A Zero-Voltage-Switching (ZVS) sinusoidal pulse width modulation (SPWM) method for three-phase four-wire inverter is proposed in order to achieve higher efficiency and power density. With the proposed modulation scheme, the ZVS operation of all switches including the main switches and the auxiliary switch can be realized. Besides, all seven switches operate at a fixed frequency. The ZVS SPWM scheme is introduced by considering the various combinations of the polarities in three-phase filter inductors currents and analysis of operating stages is presented. ZVS condition of the ZVS SPWM scheme is derived and discussions of ZVS condition for typical three-phase loads are also provided. In addition, the resonant parameters design and loss analysis are briefly investigated. Finally the proposed ZVS SPWM scheme is verified on a 10 kW inverter prototype with SiC MOSFET devices.
Maximum power extraction from wind energy system based on fuzzy logic controlAsoka Technologies
This paper proposes a variable speed control scheme for grid-connected wind energy conversion system (WECS) using permanent magnet synchronous generator (PMSG). The control algorithm tracks the maximum power for wind speeds below rated speed of wind turbines and ensures the power will not go over the rated power for wind speeds over the rated value. The control algorithm employs fuzzy logic controller (FLC) to effectively do this target. The wind turbine is connected to the grid via back-to-back PWM-VSC. Two effective computer simulation packages (PSIM and Simulink) are used to carry out the simulation effectively. The control system has two controllers for generator side and grid side converters. The main function of the generator side controller is to track the maximum power through controlling the rotational speed of the wind turbine using FLC. In the grid side converter, active and reactive power control has been achieved by controlling q-axis and d-axis current components, respectively. The d-axis current is set at zero for unity power factor and the q-axis current is controlled to deliver the power flowing from the dc-link to the electric utility grid.
Dual-function PV-ECS integrated to 3P4W distribution grid using 3M-PLL contro...Asoka Technologies
This study proposes a single-stage solar photovoltaic energy conversion system (PV-ECS) integrated to a three phase four-wire (3P4W) distribution grid with dual-function capabilities, i.e. active power transfer and power quality (PQ) enhancement at the point of interaction (PoI). The PV-ECS system comprises of a solar photovoltaic array and a voltage source inverter (VSI), supplying active power (during daytime) to the distribution grid and connected single-phase and three-phase loads. Apart from transfer of power, the system also improves the PQ at the PoI by compensating reactive power and neutral current, attenuating harmonics, correcting power factor and balancing grid currents. During night, the VSI acts as a shunt active power filter mitigating PQ issues, thereby increasing the device utilisation factor. A three-phase magnitude-phase locked loop (3M-PLL) method is utilised to extract and estimate fundamental term of load currents and an incremental conductance algorithm is applied for maximum power point tracking. To demonstrate its effectiveness, the system is modelled and its performance is simulated on MATLAB and experiments are performed on a developed prototype in the laboratory.
Development of wind and solar based ac microgrid with power quality improveme...Asoka Technologies
This work proposes a microgrid (μ-grid) integrating wind and solar photovoltaic (PV) resources, along with the battery energy storage (BES) to the three phase grid feeding the nonlinear load. The μ-grid disconcerted by probabilistic nonlinear time dependent parameters and their effects are compensated by cohesive controllers used for utility grid side voltage source converter (GVSC) and machine side VSC (MVSC). The switching controls and the reconfigurability of the μ-grid are addressed on imperative aspects of improving power quality (PQ), power reliability, nonlinear load compensation and economic utilization of resources. The nonlinear load compensation and PQ enhancement are achieved by executing modified version of the adaptive filtering technique including “momentum” based least mean square (MLMS) control technique, utilized for providing the switching control signals to the GVSC. It utilizes two preceding gradient weights for obtaining updated weight thereby improving the convergence rate and overcoming the limitation of conventional control of the same family. The MVSC acquires its switching signals from conventional vector control scheme and the encoderless estimation of speed and rotor position of the synchronous generator (SG) driven by wind turbine through back electromotive force control technique. The external environmental disturbances are overcome by utilizing perturb and observe (P&O) maximum power point (MPP) for wind optimal power extraction and adaptive P&O with variable perturbation step size for solar MPP estimation. Test results are obtained from the laboratory prototype under steady state and dynamic conditions including altering wind speed, intermittent solar insolation and variable load conditions. The PQ issues are addressed and investigated successfully.
A simplified phase shift pwm-based feedforward distributed mppt method for gr...Asoka Technologies
The modularity and decreased filter size properties have made cascaded multilevel inverters (MLIs) more applicable than conventional two-level inverters, especially in high and medium power photovoltaic (PV) applications. However, partial shading of PV modules will affect negatively the output power of the unshaded modules. There are several existing solutions in the literature to address this challenge, however almost all of them suffer from complex implementations, low efficiency, and high cost. This paper presents a new simplified feedforward distributed maximum power point tracking (MPPT) method for three-phase grid-connected cascaded MLIs. The cascaded MLI provides a modular, and highly efficient single stage power conversion for PV systems. The proposed distributed MPPT method is depending on the phase-shift pulse width modulation (PSPWM) method with a simplified implementation. The proposed method is developing a feedforward signal that is proportional to the maximum power of the individual module. Then, the current controller, and the modulating signal are multiplied with the proportionality factor of the module maximum power. Furthermore, a modified modulation compensation method without using proportional-integral (PI) controllers is introduced to solve the problem of the unbalanced three-phase PV output currents that results from PV power mismatches and shading. A case study is implemented for 15 kW PV system to investigate the performance of the proposed method. In addition, comprehensive comparisons with the previous attempts in the literature are provided to verify the superior performance of the new proposed control method.
Power Quality Assessment of Voltage Positive Feedback Based Islanding Detecti...Asoka Technologies
Islanding refers to a condition where distributed generators (DGs) inject power solely to the local load after electrical separation from power grid. Several islanding detection methods (IDMs) categorized into remote, active, and passive groups have been reported to detect this undesirable state. In active techniques, a disturbance is injected into the DG’s controller to drift a local yardstick out of the permissible range. Although this disturbance leads to more effective detections even in well-balanced island, it raises the total harmonic distortion (THD) of the output current under the normal operation conditions. This paper analyzes the power quality aspect of the modified sliding mode controller as a new active IDM for grid-connected photovoltaic system (GCPVS) with a string inverter. Its performance is compared with the voltage positive feedback (VPF) method, a well-known active IDM. This evaluation is carried out for a 1 kWp GCPVS in MATLAB/Simulink platform by measuring the output current harmonics and THD as well as the efficiency under various penetration and disturbance levels. The output results demonstrate that since the proposed disturbance changes the amplitude of the output current, it does not generate harmonics/subharmonics. Thereby, it has a negligible adverse effect on power quality. It is finally concluded that the performance of the sliding mode-based IDM is reliable from the standpoints of islanding detection and power quality.
In cascaded-type microgrid, the synchronization and power balance of distributed generators become two new issues that needs to be addressed urgently. To that end, an f-P/Q droop control is proposed in this letter, and its stability is analyzed as well. This proposed droop control is capable to achieve power balance under both resistive-inductive an resistive-capacitive loads autonomously. Compared with the inverse power factor droop control, an obvious advantage consists in extending the scope of application. Finally, the feasibility of the proposed method is verified by simulation results.
Power quality improvement in utility interactive based ac dc converter using ...Asoka Technologies
This paper highlights the power quality issues and explains the remedial measures taken by means of hybrid front-end third harmonic current injection rectifiers. Here zig-zag transformer is used as the current injection device so that the advantages pertaining to the zig-zag transformer is effectively utilized. The third harmonic current injection device along with three-level boost converter at the output stage will increase the DC-link voltage. With less boost inductance, generally half of the conventional boost converter inductance is sufficient to implement the proposed converter structure resulting in reduced ripple current and also the device rating is reduced by half of the output voltage. Moreover, the power quality is well improved using third harmonic current modulated front-end structure which is well appropriate for medium/higher power applications. The experimental prototype of hybrid front-end converter is developed in the laboratory to validate the MATLAB simulation results.
According to growth of electricity demand and the increased number of non-linear loads in power grids, providing a high quality electrical power should be considered. In this paper, Enhancement of power quality by using fuzzy based multilevel power flow controller (DPFC) is proposed. The DPFC is a new FACTS device, which its structure is similar to unified power flow controller (UPFC). In spite of UPFC, in DPFC the common dc-link between the shunt and series converters is eliminated and three-phase series converter is divided to several single-phase series distributed converters through the line. This eventually enables the DPFC to fully control all power system parameters. It, also, increases the reliability of the device and reduces its cost simultaneously. In recent years multi level inverters are used high power and high voltage applications .Multilevel inverter output voltage produce a staircase output waveform, this waveform look like a sinusoidal waveform leads to reduction in Harmonics. Fuzzy Logic is used for optimal designing of controller parameters. Application of Fuzzy Multilevel DPFC for reduction of Total Harmonic Distortion was presented. The simulation results show the improvement of power quality using DPFC with Fuzzy logic controller.
Front end buck rectifier with reduced filter size and single-loop controlAsoka Technologies
This paper presents a transformerless solution for front-end rectification, which is particularly suitable for traction applications, requiring high voltages to be stepped down to appropriate dc voltage. The proposed topology is based on pulse widthmodulation buck rectifier (current source inverter topology) and is capable of rectification and stepping down of single-phase ac supply, in a single stage. A new control scheme is proposed to achieve constant dc output voltage and sinusoidal source current, irrespective of large ripples in the dc inductor current. The proposed scheme is configured in single-loop voltage control mode. The relevant small-signal model is derived from the large-signal model using multi order decomposition. An elaborate procedure of dc filter design is discussed, for circuit operation with minimum energy storage. All analytical results are validated by numerical simulation for sinusoidal and distorted source voltage. Experimental verification is achieved through a 1.2-kW grid-connected laboratory prototype.
A Novel Design of PI Current Controller for PMSG-based Wind Turbine Consideri...Asoka Technologies
This paper presents a novel design process of decoupled PI current controller for permanent magnet synchronous generator (PMSG)-based wind turbines feeding a grid-tied inverter through back-to-back converter. Specifically, the design methodology consists of combining disturbance observer-based control (DOBC) with feedback linearization (FBL) technique to ensure nominal transient performance recovery under model uncertainty. By simplifying the DOBC under the feedback linearizing control, it is shown that the composite controller reduces to a decoupled PI current controller plus an additional term that has the main role of recovering the nominal transient performance of the feedback linearization, especially under step changes in the reference. Additionally, an anti windup compensator arises naturally into the controller when considering the control input saturation to design the DOBC. This permits to remove the effect of the saturation blocks required to limit the control input. The proposed control scheme is implemented and validated through experimentation conducted on 22-pole, 5 kW PMSG. The results revealed that the proposed technique can successfully achieve nominal performance recovery under model uncertainty as well as improved transient performances under control saturation.
Control strategy for power flow management in a pv system supplying dc loadsAsoka Technologies
The growing concern for energy saving has increased the usage of LED-based street lights, electronic chokes, compact fluorescent lamps, and inverter-fed drives. Hence, the load profile seen by the electrical grid is undergoing a notable change as these devices have to operate from a dc source. Photovoltaics (PV) being a major energy source, the aforementioned loads can be connected directly to the dc bus. A grid-connected PV system involves a power source (PV array), a power sink (load), and two power sources/sink (utility and battery), and hence, a power
flow management system is required to balance the power flow among these sources. One such system is developed for selecting the operating mode of the bidirectional converter by sensing the battery voltage. The viability of the scheme has been ascertained by performing experimental studies on a laboratory prototype. The control strategy is digitally implemented on an Altera Cyclone II Field Programmable Gate Array (FPGA) board, and the algorithm is verified for different modes of operation by varying the load. Experimental results are presented to bring out
the usefulness of the control strategy.
Single-phase solar PV system with battery and exchange of power in grid-conne...Asoka Technologies
A grid tied photovoltaic (PV) power conversion topology is presented in this study with a novel scheme of resynchronization to the grid. This scheme serves the purpose of supplying continuous power to the load along with feeding power to the grid. The control approach helps in mitigation of harmonics and improving the power quality while extracting the optimum power from the PV array. Depending on the availability of grid voltage, the proposed configuration is controlled using three approaches, defined as grid current control, Point of Common Coupling (PCC) voltage control and intentional islanding with re-synchronisation. A simple proportional integral controller manages the grid current, load voltage, battery current and DC Direct Current (DC) link voltage within these modes. Moreover, a control scheme for quick and smooth transitions among the modes is described. The robustness of the system under erratic behaviour of solar insolation, load power and disturbances in grid supply makes it a suitable choice for a residential application. The control, design and simulation results are presented to demonstrate the satisfactory operation of the proposed system.
A Unified Control and Power Management Scheme for PV-Battery-Based Hybrid Mic...Asoka Technologies
Battery storage is usually employed in Photovoltaic (PV) system to mitigate the power fluctuations due to the characteristics of PV panels and solar irradiance. Control schemes for PV-battery systems must be able to stabilize the bus voltages as well as to control the power flows flexibly. This paper proposes a comprehensive control and power management system (CAPMS) for PV-battery-based hybrid microgrids with both AC and DC buses, for both grid-connected and islanded modes. The proposed CAPMS is successful in regulating the DC and AC bus voltages and frequency stably, controlling the voltage and power of each unit flexibly, and balancing the power flows in the systems automatically under different operating circumstances, regardless of disturbances from switching operating modes, fluctuations of irradiance and temperature, and change of loads. Both simulation and experimental case studies are carried out to verify the performance of the proposed method.
Single-Stage Switched-Capacitor Module (S3CM) Topology for Cascaded Multileve...Asoka Technologies
A two-stage switched-capacitor based multilevel inverter possesses a drawback such that switches in the second stage (i.e. H-bridge) endure higher voltage stress. To resolve this problem, this letter proposes a single-stage switched-capacitor module (S3CM) topology for cascaded multilevel inverter which ensures the peak inverse voltage across all switches within the dc source voltage. Nine voltage levels can be generated with only one dc source and two incorporated capacitors. Hence, the number of isolated dc sources are significantly reduced compared to cascaded H-bridge. In addition, voltage boosting gain of two is achieved. A comparative analysis against the recent topology reveals that the proposed S3CM topology achieves switch count reduction. The operation of the proposed topology is validated through circuit analysis followed by experimental results of a single module (9-level) prototype.
Improved dynamic performance of shunt active power filter using particle swar...Asoka Technologies
In this paper, a novel particle swarm optimization (PSO) technique is proposed to tune the proportional-integral (PI) controller gain parameters for enhancing the dynamic performance of the shunt active power filter (APF). The shunt APFs are well established filter to compensate current harmonics, reactive power to maintain the power factor unity. The compensation is highly influenced by the DC-link voltage regulation.
A Dual Control Strategy for Power Sharing Improvement In Islanded Mode of AC ...Asoka Technologies
Parallel operation of inverter modules is the solution to increase the reliability, efficiency, and redundancy of inverters in microgrids. Load sharing among inverters in distributed generators (DGs) is a key issue. This study investigates the feasibility of power-sharing among parallel DGs using a dual control strategy in islanded mode of a microgrid. PQ control and droop control techniques are established to control the microgrid operation.
Three phase transformerless shunt active power filter with reduced switch cou...Asoka Technologies
Shunt active power filter is the preeminent solution against nonlinear loads, current harmonics and power quality problems. APF topologies for harmonic compensation use numerous high-power rating components and are therefore disadvantageous. Hybrid topologies combining low-power rating APF with passive filters are used to reduce the power rating of voltage source inverter. Hybrid APF topologies for high-power rating systems use a transformer with large numbers of passive components. In this paper, a novel four-switch two-leg VSI topology for a three-phase SAPF is proposed for reducing the system cost and size. The proposed topology comprises a two-arm bridge structure, four switches, coupling inductors, and sets of LC PFs. The third leg of the three-phase VSI is removed by eliminating the set of power switching devices, thereby directly connecting the phase with the negative terminals of the dc-link capacitor. The proposed topology enhances the harmonic compensation capability and provides complete reactive power compensation compared with conventional APF topologies. The new experimental prototype is tested in the laboratory to verify the results in terms of total harmonic distortion, balanced supply current, and harmonic compensation, following the IEEE-519 standard.
Development of wind and solar based ac microgrid with power quality improveme...Asoka Technologies
This work proposes a microgrid (μ-grid) integrating wind and solar photovoltaic (PV) resources, along with the battery energy storage (BES) to the three phase grid feeding the nonlinear load. The μ-grid disconcerted by probabilistic nonlinear time dependent parameters and their effects are compensated by cohesive controllers used for utility grid side voltage source converter (GVSC) and machine side VSC (MVSC). The switching controls and the reconfigurability of the μ-grid are addressed on imperative aspects of improving power quality (PQ), power reliability, nonlinear load compensation and economic utilization of resources. The nonlinear load compensation and PQ enhancement are achieved by executing modified version of the adaptive filtering technique including “momentum” based least mean square (MLMS) control technique, utilized for providing the switching control signals to the GVSC. It utilizes two preceding gradient weights for obtaining updated weight thereby improving the convergence rate and overcoming the limitation of conventional control of the same family. The MVSC acquires its switching signals from conventional vector control scheme and the encoderless estimation of speed and rotor position of the synchronous generator (SG) driven by wind turbine through back electromotive force control technique. The external environmental disturbances are overcome by utilizing perturb and observe (P&O) maximum power point (MPP) for wind optimal power extraction and adaptive P&O with variable perturbation step size for solar MPP estimation. Test results are obtained from the laboratory prototype under steady state and dynamic conditions including altering wind speed, intermittent solar insolation and variable load conditions. The PQ issues are addressed and investigated successfully.
A simplified phase shift pwm-based feedforward distributed mppt method for gr...Asoka Technologies
The modularity and decreased filter size properties have made cascaded multilevel inverters (MLIs) more applicable than conventional two-level inverters, especially in high and medium power photovoltaic (PV) applications. However, partial shading of PV modules will affect negatively the output power of the unshaded modules. There are several existing solutions in the literature to address this challenge, however almost all of them suffer from complex implementations, low efficiency, and high cost. This paper presents a new simplified feedforward distributed maximum power point tracking (MPPT) method for three-phase grid-connected cascaded MLIs. The cascaded MLI provides a modular, and highly efficient single stage power conversion for PV systems. The proposed distributed MPPT method is depending on the phase-shift pulse width modulation (PSPWM) method with a simplified implementation. The proposed method is developing a feedforward signal that is proportional to the maximum power of the individual module. Then, the current controller, and the modulating signal are multiplied with the proportionality factor of the module maximum power. Furthermore, a modified modulation compensation method without using proportional-integral (PI) controllers is introduced to solve the problem of the unbalanced three-phase PV output currents that results from PV power mismatches and shading. A case study is implemented for 15 kW PV system to investigate the performance of the proposed method. In addition, comprehensive comparisons with the previous attempts in the literature are provided to verify the superior performance of the new proposed control method.
Power Quality Assessment of Voltage Positive Feedback Based Islanding Detecti...Asoka Technologies
Islanding refers to a condition where distributed generators (DGs) inject power solely to the local load after electrical separation from power grid. Several islanding detection methods (IDMs) categorized into remote, active, and passive groups have been reported to detect this undesirable state. In active techniques, a disturbance is injected into the DG’s controller to drift a local yardstick out of the permissible range. Although this disturbance leads to more effective detections even in well-balanced island, it raises the total harmonic distortion (THD) of the output current under the normal operation conditions. This paper analyzes the power quality aspect of the modified sliding mode controller as a new active IDM for grid-connected photovoltaic system (GCPVS) with a string inverter. Its performance is compared with the voltage positive feedback (VPF) method, a well-known active IDM. This evaluation is carried out for a 1 kWp GCPVS in MATLAB/Simulink platform by measuring the output current harmonics and THD as well as the efficiency under various penetration and disturbance levels. The output results demonstrate that since the proposed disturbance changes the amplitude of the output current, it does not generate harmonics/subharmonics. Thereby, it has a negligible adverse effect on power quality. It is finally concluded that the performance of the sliding mode-based IDM is reliable from the standpoints of islanding detection and power quality.
In cascaded-type microgrid, the synchronization and power balance of distributed generators become two new issues that needs to be addressed urgently. To that end, an f-P/Q droop control is proposed in this letter, and its stability is analyzed as well. This proposed droop control is capable to achieve power balance under both resistive-inductive an resistive-capacitive loads autonomously. Compared with the inverse power factor droop control, an obvious advantage consists in extending the scope of application. Finally, the feasibility of the proposed method is verified by simulation results.
Power quality improvement in utility interactive based ac dc converter using ...Asoka Technologies
This paper highlights the power quality issues and explains the remedial measures taken by means of hybrid front-end third harmonic current injection rectifiers. Here zig-zag transformer is used as the current injection device so that the advantages pertaining to the zig-zag transformer is effectively utilized. The third harmonic current injection device along with three-level boost converter at the output stage will increase the DC-link voltage. With less boost inductance, generally half of the conventional boost converter inductance is sufficient to implement the proposed converter structure resulting in reduced ripple current and also the device rating is reduced by half of the output voltage. Moreover, the power quality is well improved using third harmonic current modulated front-end structure which is well appropriate for medium/higher power applications. The experimental prototype of hybrid front-end converter is developed in the laboratory to validate the MATLAB simulation results.
According to growth of electricity demand and the increased number of non-linear loads in power grids, providing a high quality electrical power should be considered. In this paper, Enhancement of power quality by using fuzzy based multilevel power flow controller (DPFC) is proposed. The DPFC is a new FACTS device, which its structure is similar to unified power flow controller (UPFC). In spite of UPFC, in DPFC the common dc-link between the shunt and series converters is eliminated and three-phase series converter is divided to several single-phase series distributed converters through the line. This eventually enables the DPFC to fully control all power system parameters. It, also, increases the reliability of the device and reduces its cost simultaneously. In recent years multi level inverters are used high power and high voltage applications .Multilevel inverter output voltage produce a staircase output waveform, this waveform look like a sinusoidal waveform leads to reduction in Harmonics. Fuzzy Logic is used for optimal designing of controller parameters. Application of Fuzzy Multilevel DPFC for reduction of Total Harmonic Distortion was presented. The simulation results show the improvement of power quality using DPFC with Fuzzy logic controller.
Front end buck rectifier with reduced filter size and single-loop controlAsoka Technologies
This paper presents a transformerless solution for front-end rectification, which is particularly suitable for traction applications, requiring high voltages to be stepped down to appropriate dc voltage. The proposed topology is based on pulse widthmodulation buck rectifier (current source inverter topology) and is capable of rectification and stepping down of single-phase ac supply, in a single stage. A new control scheme is proposed to achieve constant dc output voltage and sinusoidal source current, irrespective of large ripples in the dc inductor current. The proposed scheme is configured in single-loop voltage control mode. The relevant small-signal model is derived from the large-signal model using multi order decomposition. An elaborate procedure of dc filter design is discussed, for circuit operation with minimum energy storage. All analytical results are validated by numerical simulation for sinusoidal and distorted source voltage. Experimental verification is achieved through a 1.2-kW grid-connected laboratory prototype.
A Novel Design of PI Current Controller for PMSG-based Wind Turbine Consideri...Asoka Technologies
This paper presents a novel design process of decoupled PI current controller for permanent magnet synchronous generator (PMSG)-based wind turbines feeding a grid-tied inverter through back-to-back converter. Specifically, the design methodology consists of combining disturbance observer-based control (DOBC) with feedback linearization (FBL) technique to ensure nominal transient performance recovery under model uncertainty. By simplifying the DOBC under the feedback linearizing control, it is shown that the composite controller reduces to a decoupled PI current controller plus an additional term that has the main role of recovering the nominal transient performance of the feedback linearization, especially under step changes in the reference. Additionally, an anti windup compensator arises naturally into the controller when considering the control input saturation to design the DOBC. This permits to remove the effect of the saturation blocks required to limit the control input. The proposed control scheme is implemented and validated through experimentation conducted on 22-pole, 5 kW PMSG. The results revealed that the proposed technique can successfully achieve nominal performance recovery under model uncertainty as well as improved transient performances under control saturation.
Control strategy for power flow management in a pv system supplying dc loadsAsoka Technologies
The growing concern for energy saving has increased the usage of LED-based street lights, electronic chokes, compact fluorescent lamps, and inverter-fed drives. Hence, the load profile seen by the electrical grid is undergoing a notable change as these devices have to operate from a dc source. Photovoltaics (PV) being a major energy source, the aforementioned loads can be connected directly to the dc bus. A grid-connected PV system involves a power source (PV array), a power sink (load), and two power sources/sink (utility and battery), and hence, a power
flow management system is required to balance the power flow among these sources. One such system is developed for selecting the operating mode of the bidirectional converter by sensing the battery voltage. The viability of the scheme has been ascertained by performing experimental studies on a laboratory prototype. The control strategy is digitally implemented on an Altera Cyclone II Field Programmable Gate Array (FPGA) board, and the algorithm is verified for different modes of operation by varying the load. Experimental results are presented to bring out
the usefulness of the control strategy.
Single-phase solar PV system with battery and exchange of power in grid-conne...Asoka Technologies
A grid tied photovoltaic (PV) power conversion topology is presented in this study with a novel scheme of resynchronization to the grid. This scheme serves the purpose of supplying continuous power to the load along with feeding power to the grid. The control approach helps in mitigation of harmonics and improving the power quality while extracting the optimum power from the PV array. Depending on the availability of grid voltage, the proposed configuration is controlled using three approaches, defined as grid current control, Point of Common Coupling (PCC) voltage control and intentional islanding with re-synchronisation. A simple proportional integral controller manages the grid current, load voltage, battery current and DC Direct Current (DC) link voltage within these modes. Moreover, a control scheme for quick and smooth transitions among the modes is described. The robustness of the system under erratic behaviour of solar insolation, load power and disturbances in grid supply makes it a suitable choice for a residential application. The control, design and simulation results are presented to demonstrate the satisfactory operation of the proposed system.
A Unified Control and Power Management Scheme for PV-Battery-Based Hybrid Mic...Asoka Technologies
Battery storage is usually employed in Photovoltaic (PV) system to mitigate the power fluctuations due to the characteristics of PV panels and solar irradiance. Control schemes for PV-battery systems must be able to stabilize the bus voltages as well as to control the power flows flexibly. This paper proposes a comprehensive control and power management system (CAPMS) for PV-battery-based hybrid microgrids with both AC and DC buses, for both grid-connected and islanded modes. The proposed CAPMS is successful in regulating the DC and AC bus voltages and frequency stably, controlling the voltage and power of each unit flexibly, and balancing the power flows in the systems automatically under different operating circumstances, regardless of disturbances from switching operating modes, fluctuations of irradiance and temperature, and change of loads. Both simulation and experimental case studies are carried out to verify the performance of the proposed method.
Single-Stage Switched-Capacitor Module (S3CM) Topology for Cascaded Multileve...Asoka Technologies
A two-stage switched-capacitor based multilevel inverter possesses a drawback such that switches in the second stage (i.e. H-bridge) endure higher voltage stress. To resolve this problem, this letter proposes a single-stage switched-capacitor module (S3CM) topology for cascaded multilevel inverter which ensures the peak inverse voltage across all switches within the dc source voltage. Nine voltage levels can be generated with only one dc source and two incorporated capacitors. Hence, the number of isolated dc sources are significantly reduced compared to cascaded H-bridge. In addition, voltage boosting gain of two is achieved. A comparative analysis against the recent topology reveals that the proposed S3CM topology achieves switch count reduction. The operation of the proposed topology is validated through circuit analysis followed by experimental results of a single module (9-level) prototype.
Improved dynamic performance of shunt active power filter using particle swar...Asoka Technologies
In this paper, a novel particle swarm optimization (PSO) technique is proposed to tune the proportional-integral (PI) controller gain parameters for enhancing the dynamic performance of the shunt active power filter (APF). The shunt APFs are well established filter to compensate current harmonics, reactive power to maintain the power factor unity. The compensation is highly influenced by the DC-link voltage regulation.
A Dual Control Strategy for Power Sharing Improvement In Islanded Mode of AC ...Asoka Technologies
Parallel operation of inverter modules is the solution to increase the reliability, efficiency, and redundancy of inverters in microgrids. Load sharing among inverters in distributed generators (DGs) is a key issue. This study investigates the feasibility of power-sharing among parallel DGs using a dual control strategy in islanded mode of a microgrid. PQ control and droop control techniques are established to control the microgrid operation.
Three phase transformerless shunt active power filter with reduced switch cou...Asoka Technologies
Shunt active power filter is the preeminent solution against nonlinear loads, current harmonics and power quality problems. APF topologies for harmonic compensation use numerous high-power rating components and are therefore disadvantageous. Hybrid topologies combining low-power rating APF with passive filters are used to reduce the power rating of voltage source inverter. Hybrid APF topologies for high-power rating systems use a transformer with large numbers of passive components. In this paper, a novel four-switch two-leg VSI topology for a three-phase SAPF is proposed for reducing the system cost and size. The proposed topology comprises a two-arm bridge structure, four switches, coupling inductors, and sets of LC PFs. The third leg of the three-phase VSI is removed by eliminating the set of power switching devices, thereby directly connecting the phase with the negative terminals of the dc-link capacitor. The proposed topology enhances the harmonic compensation capability and provides complete reactive power compensation compared with conventional APF topologies. The new experimental prototype is tested in the laboratory to verify the results in terms of total harmonic distortion, balanced supply current, and harmonic compensation, following the IEEE-519 standard.
Comunicação Social: Jornalismo FIAM
Disciplina Cultura Comunicação e Mídia
Conteúdo:
O que é Cultura?
1.1. A cultura como dispositivo comunicacional
1.2. Etnocentrismo e Relativismo Cultural
1.3. Identidades e diferenças
A cultura na Contemporaneidade
A identidade cultural na pós modernidade (Stuart Hall)
Enhancing the Efficiency of a Torque Converter Clutch (TCC)Sharon Lin
Using a computational simulation, we can create analytical data based on the inputs given by a commercially available vehicle, determining the overall efficiency of different models of engines without needing any physical models.
Fuzzy logic Technique Based Speed Control of a Permanent Magnet Brushless DC...IJMER
This paper presents an analysis by which the dynamic performances of a permanent magnet
brushless dc (PMBLDC) motor drive with different speed controllers can be successfully predicted. The
control structure of the proposed drive system is described. The dynamics of the drive system with a
classical proportional-integral-derivative (PID) and Fuzzy-Logic (FL) speed controllers are presented.
The simulation results for different parameters and operation modes of the drive system are investigated
and compared. The results with FL speed controller show improvement in transient response of the
PMBLDC drive over conventional PID controller. Moreover, useful conclusions stemmed from such a
study which is thought of good use and valuable for users of these controllers
MODELING AND DESIGN OF CRUISE CONTROL SYSTEM WITH FEEDFORWARD FOR ALL TERRIAN...csandit
This paper presents PID controller with feed-forward control. The cruise control system is one
of the most enduringly popular and important models for control system engineering. The
system is widely used because it is very simple to understand and yet the control techniques
cover many important classical and modern design methods. In this paper, the mathematical
modeling for PID with feed-forward controller is proposed for nonlinear model with
disturbance effect. Feed-forward controller is proposed in this study in order to eliminate the
gravitational and wind disturbance effect. Simulation will be carried out . Finally, a C++
program written and feed to the microcontroller type AMR on our robot
Model Validation and Control of an In-Wheel DC Motor Prototype for Hybrid El...Scientific Review SR
In this paper, a mathematical model and a controller for a DC motor are developed for the
construction of an in-wheel motor. In-wheel motors can be used in hybrid electric vehicles to provide traction
force of front or rear wheels. The model identification is achieved using a simple and low cost data acquisition
system. An Arduino Uno embedded board system is used to collect data from sensors to a computer and for
control purposes. Data processing is performed using Matlab/Simulink. Validations of the devel oped
mathematical model and controller performance are carried out by comparing simulation and experimental results.
The results obtained show that the mathematical model is accurate enough to assist in speed controller design and
implementation.
MODELING AND DESIGN OF CRUISE CONTROL SYSTEM WITH FEEDFORWARD FOR ALL TERRIAN...cscpconf
This paper presents PID controller with feed-forward control. The cruise control system is one of the most enduringly popular and important models for control system engineering. The system is widely used because it is very simple to understand and yet the control techniques cover many important classical and modern design methods. In this paper, the mathematical modeling for PID with feed-forward controller is proposed for nonlinear model with disturbance effect. Feed-forward controller is proposed in this study in order to eliminate the gravitational and wind disturbance effect. Simulation will be carried out . Finally, a C++ program written and feed to the microcontroller type AMR on our robot
Permanent magnet direct current motors (PMDCM) are widely used in various applications such as space technologies, personal computers, medical, military, robotics, electrical vehicles, etc. In this paper, the mathematical model of PMDCM is designed and simulated using MATLAB software. The PMDCM speed is controlled using rate feedback controller due to its ability of improving system damping. To improve the controller performance, it’s parameters are tuned using genetic algorithm (GA) and direct search (DS) techniques. The tuning process based on different performance criteria. The most four common performance criteria used in this paper are JIAE (Integral of Absolute Error), JISE (Integral of Square Error), JITAE (Integral of Time-Weighted Absolute Error), and JITSE (Integral of Time-Weighted Square Error). The results obtained from these evolutionary techniques are compared. The results show an obvious improvement in system performance including enhancing the transient and steady state of PMDCM speed responses for all performance criteria.
2.a neuro fuzzy based svpwm technique for pmsm (2)EditorJST
In the present scenario, static frequency converter based variable speed synchronous motors has
become very familiar and advantage to other drive system, especially low speed and high power applications.
Unlike the induction motor, the synchronous motor can be operated at variable power factor (leading, lagging
or unity) as desired. So, there is an increasing use of synchronous motors as adjustable speed drives. The PWM
technique is very useful to VSI drive for achieving efficient and smooth operation and free from torque
pulsations and cogging, lower volume and weight and provides a higher frequency range compared to CSI
drives. Even for voltage source inverter, the commutation circuit is not needed, if the self-extinguishing
switching devices are used. This paper proposes a concept of Neuro-fuzzy based control strategy which is used
for controlling the PMSM. The total work mainly concentrates on optimum control of PMSM with maximum
voltage utilization with less switching losses.
STUDY AND ANALYSIS OF DIFFERENTIAL CONTROLLED CONTINUOUSLY VARIABLE DRIVEJournal For Research
Now a day's development trends in car industry and mobile machines are driven by universal concerns on energy limitations and greenhouse gases reduction, more energy efficient and environmentally friendly vehicles will be needed. As the increasing concerns in the impact of vehicle emissions of carbon dioxides and Nitrogen oxides on the biosphere combined with today's shortage fuel, hence need to find alternate fuel solutions or develop the transmission system in such a way that lower consumption and lower emission should takes place. Continuously variable drive is the type of automatic transmission that allows selection of infinite number of transmission ratios within the finite range i.e. between minimum and maximum value. Continuously variable drive is 34.91% more efficient than that of manual transmission. In order to achieve emission reduction and fuel economy needs to improve fuel efficiency. Continuously variable drive can be improved by coupling differential gear assembly to one of variable speed drives; we can increase the speed variation range at the expense of the horse power range. Numerous combinations of the variables are possible.
This work proposes an optimization algorithm to control speed of a permanent magnet synchronous motor (PMSM) during starting and speed reversal of motor, as well as during load disturbance conditions. The objective is to minimize the integral absolute control error of the PMSM shaft speed to achieve fast and accurate speed response under load disturbance and speed reversal conditions. The maximum overshoot, peak time, settling time and rise time of the motor is also minimized to obtain efficient transient speed response. Optimum speed control of PMSM is obtained with the aid of a PID speed controller. Modified Particle Swarm Optimization (MPSO) and Ant Colony Optimization (ACO) techniques has been employed for tuning of the PID speed controller, to determine its gain coefficients (proportional, integral and derivative). Simulation results demonstrate that with use of MPSO and ACO techniques improved control performance of PMSM can be achieved in comparison to the classical Ziegler-Nichols (Z-N) method of PID tuning.
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.
A NEW APPROACH TO DTC METHOD FOR BLDC MOTOR ADJUSTABLE SPEED DRIVEScscpconf
This paper proposes a new approach to direct torque control (DTC) method for brushless direct current (BLDC) motor drives. In conventional DTC method, two main reference parameters are used as: flux and torque. In this paper, the new approach has been proposed to improve the BLDC motor dynamic performance. A main difference from the conventional method of it was that only one reference parameter (speed) was used to control the BLDC motor and the second control parameter (flux) was obtained from speed error through the proposed control algorithm. Thus, the DTC performance has been especially improved on systems which need variable speed and torque during operation, like electric vehicles. The dynamic models of the BLDC and the DTC method have been created on Matlab/Simulink. The proposed method has been confirmed and verified by the dynamic simulations on different working conditions.
Modeling and simulation of vehicle windshield wiper system using h infinity l...Mustefa Jibril
Vehicle windshield wiper system increases the driving safety by contributing a clear shot viewing to the
driver. In this paper, modelling, designing and simulation of a vehicle windshield wiper system with robust control
theory is done successfully. H loop shaping and robust pole placement controllers are used to improve the
wiping speed by tracking a reference speed signals. The reference speed signals used in this paper are step and sine
wave signals. Comparison of the H loop shaping and robust pole placement controllers based on the two
reference signals is done and convincing results have been obtained. Finally the comparative results prove the
effectiveness of the proposed H Loop Shaping controller to improve the wiping mechanism for the given two
reference signals.
1. ATK Deployment Damper Concept
Acknowledgments
Special thanks to: John Durkee, Professor Paden, Professor
Theogarajan, Trevor Marks, Greg Dahlen, Casey Hare, Kirk
Fields, Dave Bothman, and Stephen Chen
Wyatt Rodgers, Thomas Rode, Holden Tamchin, Michael Deas, Casey Duncan
Abstract
ATK desired a novel damper design that could improve on the
linear torque-speed relationship provided by dampers today.
The goal of this project was to create a novel damping method
that resulted in a constant velocity over a range of input torques.
Multiple design concepts were considered, prototyped, and
modeled. The chosen concept was tested and compared to the
predicted performance provided by the modeling. The results of
the testing indicate that the damper concept has the potential to
provide much improved performance over dampers commonly
used in the aerospace industry today.
Modelling
The described system and SMC approach were simulated
using MATLab and Simulink with the following block diagram,
shown below in Figure 4. An accurate Simulink model is an
extremely powerful tool in optimizing the damper performance.
Physical parameters including impedances, friction, controller
speed, and motor constants can all be changed and simulated
to view their effect on damper performance. The Simulink
modeling provides the theoretical damper behavior which we
would later compare to the testing results.
Figure 1. Desired Damper Behavior
Figure 3. Proposed Ultimate Design Rendering
Figure 4. Simulink Model of SMC Damper System
Prototype Testing and Results
We built a testing mount to measure the torque-speed
relationship of the damper. A drive motor supplied an input
torque and rotation to the damper and the data was recorded
with LabVIEW. We tested the dampers at multiple control
speeds. Using the test data, we proved that our concept was a
viable method of damper control. We compared the raw data to
data from our Simulink model to prove that it accurately
predicted the damper performance. The graph in Figure 5
shows the Simulink data in blue and the raw data overlaid in
red.
Figure 5. Testing Setup and Results
Recommendations for Future Work
Our work has provided reason to believe that a better damper
can be designed using Sliding Mode Control with a DC motor
to provide a vertical torque speed relationship. Through our
testing, we proved that the Simulink model is an accurate
representation. From the modeling, we can determine the
required design parameters for a desired function. The key
design relationship of the system is given by the equation
∆𝝎 =
𝑲 𝒎
𝟐
𝑱𝑹
𝝎 𝒅𝒆𝒔∆𝒕.
For best behavior, this change in speed should be minimized.
Known values for Km and R can be cataloged from DC motor
suppliers to create a design space that, along with knowing the
limitation of the control system response time ∆𝒕, shows the
possible applications for this type of system. The concept of
using Sliding Mode Control to achieve an almost perfectly
vertical torque speed relationship has been confirmed through
the simulation.
Proposed Design Concept
The design concept was limited by not allowing fluid or friction
based dampers. We chose to explore the use of a DC motor as a
means of damping. When the leads of a DC motor are shorted,
the EMF generated by the spinning system provides a torque
that resists the motion of the motor. A DC motor has a linear
torque-speed relationship when ‘shorted’, and very little
damping when ‘open’. The region shown in figure 2a shows the
range of torques that a DC motor is capable of producing over a
range of speeds, by manipulating the resistance between the
leads. We explored the use of Sliding Mode Control (SMC) in
order to achieve constant speed over a range of torques. Figure
2b shows the theoretical torque-speed relationship that can be
achieved using SMC.
Figure 2. DC Motor Performance and SMC Concept
ME189 Team 2 June 6, 2014