The document summarizes a research paper on modeling and controlling a hexagram inverter for driving a three-phase induction motor. Some key points:
1) A hexagram inverter consists of six interconnected voltage source inverters arranged in a hexagonal structure that can drive either a three-phase or six-phase motor.
2) The hexagram inverter has advantages over other multilevel inverters like reduced components, built-in redundancy, and lower voltage stress on switches.
3) A simulation model of a hexagram inverter driving a three-phase induction motor was developed in Matlab/Simulink to study the drive performance under different operating conditions.
This document discusses single phase to three phase matrix converters for traction drives. It provides an introduction to matrix converters and describes how a single phase to three phase AC matrix converter works using the separation and link method. The document outlines the 16 possible switching states and shows the switching patterns. It then compares a conventional single to three phase AC conversion method using a DC link to the proposed single to three phase AC matrix converter. The matrix converter provides direct AC-AC conversion without reactive elements, four quadrant operation, and independent control of output voltage, frequency and power factor. However, it requires more switches and a more complex control strategy. The document concludes the proposed converter is suitable for railway traction and other applications.
Comparison of Multilevel Inverter Topologies for STATCOM ApplicationsIJERA Editor
In this paper is to present an comparison of four different STATCOM multilevel inverter topologies which are suitable to be connected to the un-linear loads and unbalancing loads. The majority of power consumption has been drawn in reactive loads. These loads are drawn in low power factor and therefore give rise to reactive power burden in the power system. So that STATCOM controller is used to compensate reactive power, correction of power factor and elimination of current harmonics. This paper mainly focuses the analysis issues of the Cascade H-bridge, Incremental cascade H-bridge, Incremental cascade I–bridge and Incremental – reduction cascade H-bridge multilevel topologies with PWM technique for STATCOM applications; Inverter operation play a vital in STATCOM, presenting a methods for best suitable in the point of low THD, better output, cost and efficiency. MATLAB/SIMULINK results are present in this paper of multilevel inverter four topologies for STATCOM applications with Instantaneous p – q theory controller implemented.
A novel four wire inverter system using SVPWM technique for ups applicationsIRJET Journal
This document describes a novel four-wire inverter system using space vector pulse width modulation (SVM) technique for uninterruptible power supply (UPS) applications. It introduces the concept of SVM for four-wire voltage source inverters. A four-wire inverter provides a neutral connection for three-phase four-wire systems to handle neutral current from unbalanced or non-linear loads. The SVM technique approximates the reference voltage vector during each sampling interval using the three nearest inverter switching state vectors. Simulation results using MATLAB/Simulink analyze the performance of the four-wire SVM inverter under different loading conditions in terms of total harmonic distortion.
This document presents a comparison of different carrier-based pulse width modulation (PWM) strategies for controlling a five-level Z-source diode-clamped inverter. It first provides background on multilevel inverters and Z-source inverters. It then describes the operating principles of the Z-source inverter and equations for its output voltage. Simple boost control is presented as the control method. Three carrier-based PWM strategies - alternative phase opposition disposition, phase opposition disposition, and phase disposition - are described and their performance is evaluated through MATLAB simulations. The results show that alternative phase opposition disposition provides the highest output voltage boost but also the highest total harmonic distortion, while phase disposition has the lowest boost but also the lowest harmonic
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
POWER SYSTEM SIMULATION LAB-1 MANUAL (ELECTRICAL - POWER SYSTEM ENGINEERING )Mathankumar S
This document discusses the computation of parameters for single and double circuit transmission lines. It provides the theoretical background on line parameters such as resistance, inductance, capacitance. Formulas are given for calculating inductance and capacitance based on the geometric mean distance and radius for different conductor arrangements including single circuit, three phase symmetrical, asymmetrical transposed lines and double circuit transposed lines. Sample exercises are given to calculate the inductance and capacitance of given transmission line configurations and verify the results using software.
This document discusses speed control and four quadrant operation of a brushless DC motor (BLDC). It presents the mathematical model of a BLDC motor and describes the PI speed controller and hysteresis current controller used. It explains how the motor can be controlled to operate in all four quadrants (forward/reverse speed and torque) by changing the phase energization based on rotor position from hall sensors. A simulation model of the complete BLDC drive system is developed using MATLAB to validate the four quadrant control approach. The model achieves direction reversal from clockwise to counterclockwise without stopping at a standstill position first.
Power factor improvement in switched reluctance motor drive using pwmIAEME Publication
This document discusses improving the power factor of a switched reluctance motor (SRM) drive system by using a three-level pulse width modulation (PWM) converter. A conventional SRM drive using a diode bridge rectifier produces high current harmonics and a poor power factor. The proposed system uses a PWM converter as the front-end converter to improve the power factor at the AC mains supply with low current harmonics. The performance of the proposed SRM drive system with the PWM converter is modeled and simulated in Matlab/Simulink. The results show the system is capable of improving the power factor close to unity while meeting IEEE standards for total harmonic distortion and power quality.
This document discusses single phase to three phase matrix converters for traction drives. It provides an introduction to matrix converters and describes how a single phase to three phase AC matrix converter works using the separation and link method. The document outlines the 16 possible switching states and shows the switching patterns. It then compares a conventional single to three phase AC conversion method using a DC link to the proposed single to three phase AC matrix converter. The matrix converter provides direct AC-AC conversion without reactive elements, four quadrant operation, and independent control of output voltage, frequency and power factor. However, it requires more switches and a more complex control strategy. The document concludes the proposed converter is suitable for railway traction and other applications.
Comparison of Multilevel Inverter Topologies for STATCOM ApplicationsIJERA Editor
In this paper is to present an comparison of four different STATCOM multilevel inverter topologies which are suitable to be connected to the un-linear loads and unbalancing loads. The majority of power consumption has been drawn in reactive loads. These loads are drawn in low power factor and therefore give rise to reactive power burden in the power system. So that STATCOM controller is used to compensate reactive power, correction of power factor and elimination of current harmonics. This paper mainly focuses the analysis issues of the Cascade H-bridge, Incremental cascade H-bridge, Incremental cascade I–bridge and Incremental – reduction cascade H-bridge multilevel topologies with PWM technique for STATCOM applications; Inverter operation play a vital in STATCOM, presenting a methods for best suitable in the point of low THD, better output, cost and efficiency. MATLAB/SIMULINK results are present in this paper of multilevel inverter four topologies for STATCOM applications with Instantaneous p – q theory controller implemented.
A novel four wire inverter system using SVPWM technique for ups applicationsIRJET Journal
This document describes a novel four-wire inverter system using space vector pulse width modulation (SVM) technique for uninterruptible power supply (UPS) applications. It introduces the concept of SVM for four-wire voltage source inverters. A four-wire inverter provides a neutral connection for three-phase four-wire systems to handle neutral current from unbalanced or non-linear loads. The SVM technique approximates the reference voltage vector during each sampling interval using the three nearest inverter switching state vectors. Simulation results using MATLAB/Simulink analyze the performance of the four-wire SVM inverter under different loading conditions in terms of total harmonic distortion.
This document presents a comparison of different carrier-based pulse width modulation (PWM) strategies for controlling a five-level Z-source diode-clamped inverter. It first provides background on multilevel inverters and Z-source inverters. It then describes the operating principles of the Z-source inverter and equations for its output voltage. Simple boost control is presented as the control method. Three carrier-based PWM strategies - alternative phase opposition disposition, phase opposition disposition, and phase disposition - are described and their performance is evaluated through MATLAB simulations. The results show that alternative phase opposition disposition provides the highest output voltage boost but also the highest total harmonic distortion, while phase disposition has the lowest boost but also the lowest harmonic
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
POWER SYSTEM SIMULATION LAB-1 MANUAL (ELECTRICAL - POWER SYSTEM ENGINEERING )Mathankumar S
This document discusses the computation of parameters for single and double circuit transmission lines. It provides the theoretical background on line parameters such as resistance, inductance, capacitance. Formulas are given for calculating inductance and capacitance based on the geometric mean distance and radius for different conductor arrangements including single circuit, three phase symmetrical, asymmetrical transposed lines and double circuit transposed lines. Sample exercises are given to calculate the inductance and capacitance of given transmission line configurations and verify the results using software.
This document discusses speed control and four quadrant operation of a brushless DC motor (BLDC). It presents the mathematical model of a BLDC motor and describes the PI speed controller and hysteresis current controller used. It explains how the motor can be controlled to operate in all four quadrants (forward/reverse speed and torque) by changing the phase energization based on rotor position from hall sensors. A simulation model of the complete BLDC drive system is developed using MATLAB to validate the four quadrant control approach. The model achieves direction reversal from clockwise to counterclockwise without stopping at a standstill position first.
Power factor improvement in switched reluctance motor drive using pwmIAEME Publication
This document discusses improving the power factor of a switched reluctance motor (SRM) drive system by using a three-level pulse width modulation (PWM) converter. A conventional SRM drive using a diode bridge rectifier produces high current harmonics and a poor power factor. The proposed system uses a PWM converter as the front-end converter to improve the power factor at the AC mains supply with low current harmonics. The performance of the proposed SRM drive system with the PWM converter is modeled and simulated in Matlab/Simulink. The results show the system is capable of improving the power factor close to unity while meeting IEEE standards for total harmonic distortion and power quality.
Design and Control of Switched-Inductor Quasi-Z-Source Inverter for Photovolt...irjes
The conventional Z-Source Inverter (ZSI) used for photovoltaic applications has certain
shortcomings such as high stress across the passive components and low boost factor. This paper presents the
design and analysis of three phase switched inductor quasi Z-source inverter (SL-QZSI) for photovoltaic (PV)
applications. The wide voltage gain and the compensation for dead time effect of SL-QZSI with the help of
shoot-through states makes it suitable for PV application. Modulation strategies such as Simple boost,
Maximum boost and Constant maximum boost control methods are investigated for the operation and control
of SL-QZSI. PV source is modeled in MATLAB and incremental & conductance MPPT algorithm is
implemented .Simulation of the SL-QZSI circuit powered by PV source is carried out by implementing
maximum boost control method and the performance parameters are discussed.
Space Vector of Three Phase Three level Neutral Point Clamped Quasi Z Source ...IJTET Journal
Space vector of three phase three level neutral point clamped quasi z source inverter is proposed in this paper. Space vector modulation is the pulse width modulation consists of number of switching states. Space vector pulse width modulation technique utilizes 15% more power from DC source. Harmonics are reduced by the presence of switching states. Quasi Z-source inverter is advanced topologies which performs both boost and buck operation of a converter. The proposed inverter obtains continuous input current and the boost converter is not needed. So, maximum voltage can be obtained in the load and system complexity is reduced. Maximum power can be obtained from the solar panel by using MPPT. The implementation of MPPT is to operate a PV array under constant voltage and power reference to modify the duty cycle of the inverter.The simulation of proposed topology is done in MATLAB/SIMULINK software.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
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.
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.
Analysis of the Performance of the Drive of the Z source Induction Motor Powe...IJSRED
This document analyzes the performance of a Z-source induction motor powered by a converter. It first provides background on Z-source inverters and their advantages over traditional inverters, including their ability to boost voltage. It then describes the functional principles of a Z-source inverter, including its active states, non-shoot-through zero state, and shoot-through zero state. The document aims to determine parameters of the Z-source inverter like boost factor, output voltages, and voltage gain for maximum constant boost control through simulation and experiments.
Speed Control System for BLDC Motor by using Direct Back EMF Detection Mathodijtsrd
BLDC motors are used in many industrial and traction applications due to high efficiency, low maintenance and high torque. For good performance of BLDC motors, the accurate knowledge of the rotor position is required. The need for the rotor position information in BLDC motors have been satisfied by use of some form of rotor position sensors. But to reduce cost, complexity and also to improve reliability of the system, sensor less drive system is preferred. In this paper, the development of sensor less control system for BLDC motor using a direct back EMF detection method is presented and simulation for proposed system is done with the help of MATLAB SIMULINK. Soe Sandar Aung | Thet Naing Htun "Speed Control System for BLDC Motor by using Direct Back EMF Detection Mathod" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd26624.pdfPaper URL: https://www.ijtsrd.com/engineering/electrical-engineering/26624/speed-control-system-for-bldc-motor-by-using-direct-back-emf-detection-mathod/soe-sandar-aung
This document discusses selective harmonic elimination pulse width modulation (SHEPWM) for multilevel inverters using a generalized Hopfield neural network. It begins with an abstract that introduces multilevel inverters, SHEPWM, and the use of a generalized Hopfield neural network for SHEPWM. It then provides more details on the background and concepts of multilevel inverters, SHEPWM, and the Fourier expansion of the staircase output voltage waveform generated by multilevel inverters. The document focuses on applying SHEPWM to eliminate lower order harmonics from the output waveform using a generalized Hopfield neural network approach.
This document presents a comparative study of five-level and seven-level diode-clamped inverters controlled by space vector pulse width modulation (SVPWM). MATLAB/SIMULINK models of the two inverter topologies were developed. SVPWM control algorithms based on symmetrical sequence were used for each inverter. Both inverters were simulated driving an induction motor. The results showed that the seven-level inverter produced less harmonic distortion and torque fluctuations in the motor, while the five-level inverter had lower commutation losses. The seven-level inverter provided better motor dynamic response.
In this work, an accurate formulation and estimation of stray power losses in induction machines are proposed. Stray losses are estimated by derived formulas based on the leakage fluxes from the induction machine windings. These leakage fluxes induce voltage drops in the machine stator and rotor iron cores and eddy currents in the machine windings, causing stray power losses in the machine iron cores and windings. By adding these losses, a completed estimation of stray losses can be obtained and implemented in the equivalent machine circuit. The stray losses are represented by stray loss resistances connected in series with the stator and rotor circuits. Due to the stray loss in the rotor circuit depending largely on the machine slip this may be omitted without influencing the accuracy of stray loss calculations. The obtained formulas of stray loss estimation are practically satisfied. An accurate loss calculation in induction machines is very useful in the energy-saving issue.
Cascaded h bridge multilevel inverter in a three phase eleven leveleSAT Journals
Abstract
This paper essentially concentrates on the design and implementation of a unique topology for a three phase eleven level
cascaded H-bridge multilevel cluverter by employing different kinds of switching schemes. The basic purpose of this paper is to
enhance the number of voltage level at the output without addition of any complexity to power circuit.
The main advantages of this proposed topology is to scale down the THD and reducing electromagnetic interface EMI generation
and high voltage with very close to sine waveform. In this paper, severel kinds of carrier pulse width modulation techniques are
proposed as which scale down the total harmonic distortion and improve the out voltage from the proposed topology and POD
modulation techniques reduce the THD. A number of H-bridge arranged in cascaded to increase the voltage level with the
different switching schemes analyzed in this paper. It is observed that this new topology can be recommended to three phase
eleven level cascaded H-bridge inverter for the best and optimum performance over the conventional methods. This performance
in optimized in the eleven level of inverter.
Improving the fundamental waveforms and reducing the total harmonic distortion by using 60 IGBTs and switching is arranged
by a topology in cascaded manners.
The simulation model is produced by MATLAB2009 software version.
Key Words: Cascaded H-bridge multilevel inverter, different phase pulse width modulation, total harmonic
distortionTHD, EMI
This document summarizes key concepts about three-phase systems. It defines a three-phase system as having three sinusoidal voltages differing in phase by 120 degrees. The voltages can form a positive or negative sequence. Three-phase systems are commonly used for power generation, transmission, and distribution due to their ability to transmit more power with less material. Formulas are provided for calculating line voltages, currents, and power in balanced and unbalanced three-phase systems. Advantages of three-phase systems like constant torque and easier starting of motors are also discussed.
Comparative Evaluation of Generalized Multicell Impedance Source Inverter for...IJPEDS-IAES
Voltage-Source Inverter is limited by its only voltage step-down operation. In adding with extra boosting the flexibility is kept active for the number of semiconductors which is unchanged, voltage-type Z-source inverter was earlier proposed. This new class of inverter is generally less sensitive to electromagnetic noises. However, their boosting capabilities are anyhow less with high component stresses and poorer spectral performances caused by low modulation index ratios. Their boosting gains are, therefore, restricted in practice. To overcome these we use the generalized switched-inductor Z- source inverter is proposed, By comparing with PWM technique and SPWM technique, whose extra boosting abilities and other advantages have been verified in simulation analysis and experiment.
Distance Algorithm for Transmission Line with Mid-Point Connected STATCOMIRJET Journal
This document presents an adaptive zone selection algorithm for distance protection of a transmission line with a midpoint connected STATCOM device. The algorithm aims to address challenges to distance protection posed by the presence of the STATCOM. It investigates the impact of the STATCOM on apparent impedance seen by distance relays under different fault conditions using EMTDC/PSCAD software. An adaptive setting is proposed that calculates a new reach based on system and STATCOM parameters to ensure proper operation of distance relays for both underreach and overreach scenarios. The performance of the proposed adaptive algorithm is evaluated through simulations of various single line to ground and three phase fault cases with different fault locations, resistances and system load angles.
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.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
This paper proposes the use of Embedded EZ-source
inverter system (EZSI) as a single stage power conversion
concept for adjustable speed drives (ASD) in photovoltaic
applications. Open loop and closed loop control strategy of
EZSI system are proposed. EZSI produces the same voltage
gain as Z-source inverter (ZSI) but due to the DC sources
embedded within the X- shaped impedance network, it has
the added advantage of inherent source filtering capability
and also reduced capacitor sizing. This is attained without
any extra passive filters. By controlling the shoot-through
duty ratio and modulation index, EZSI system can produce
any desired AC output voltage even greater than DC rail
voltage and it also provides ride-through capability under
voltage sag. These advantages are more significant for
adjustable speed drive (ASD) applications in order to regulate
the speed. The operational analysis, control strategy and
simulation results exemplify that an EZSI is the most
promising technique for renewable energy applications in
order to reduce the overall system complexity and thereby
improving the inverter efficiency.
Cascaded h bridge multilevel inverter for induction motor driveseSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Efficiency Optimized Brushless DC Motor Drive based on Input Current Harmonic...IJPEDS-IAES
This paper describes efficiency improvement of a position sensorless
brushless dc motor with improved pulse width modulation scheme for the
inverter compared to existing ones. This is based on Selective Harmonic
Elimination. The proposed method reduces Total Harmonic Distortion from
the input current and armature flux and thereby reducing the core losses.
Also the power requirement with the proposed switching technique is much
lesser than the existing switching scheme. The effectiveness of the proposed scheme is demonstrated through simulation and experimental results.
Induction Motors Faults Detection Based on Instantaneous Power Spectrum Analy...IDES Editor
A method of induction motor diagnostics based on
the analysis of three-phase instantaneous power spectra has
been offered. Its implementation requires recalculation of
induction motor voltages, aiming at exclusion from induction
motor instantaneous three-phase power signal the component
caused by supply mains dissymmetry and unsinusoidality. The
recalculation is made according to the motor known
electromagnetic parameters, taking into account the
electromotive force induced in stator winding by rotor currents.
The results of instantaneous power parameters computation
proved efficiency of this method in case of supply mains voltage
dissymmetry up to 20%. The offered method has been tested
by experiments. Its applicability for detection of several stator
and rotor winding defects appeared in motor simultaneously
has been proved. This method also makes it possible to
estimate the extent of defects development according to the
size of amplitudes of corresponding harmonics in the spectrum
of total three phase power signal.
This document contains 20 multiple choice questions from GATE EE 2007 exam. It provides the questions, solutions and explanations for each question in detail. The key details are:
- The document contains one mark multiple choice questions on topics like transistors, voltage regulators, transformer connections, generator scheduling, HVDC systems, electric field distribution, op-amps, system stability, time variant systems, sampling, matrix rank, thyristor converters etc.
- For each question, the solutions clearly explain the concepts and calculations involved in arriving at the correct option. Relevant circuit diagrams and equations are included.
- The level of detail in the solutions and explanations is quite high as it is aimed to help students prepare for competitive exams
Design and Control of Switched-Inductor Quasi-Z-Source Inverter for Photovolt...irjes
The conventional Z-Source Inverter (ZSI) used for photovoltaic applications has certain
shortcomings such as high stress across the passive components and low boost factor. This paper presents the
design and analysis of three phase switched inductor quasi Z-source inverter (SL-QZSI) for photovoltaic (PV)
applications. The wide voltage gain and the compensation for dead time effect of SL-QZSI with the help of
shoot-through states makes it suitable for PV application. Modulation strategies such as Simple boost,
Maximum boost and Constant maximum boost control methods are investigated for the operation and control
of SL-QZSI. PV source is modeled in MATLAB and incremental & conductance MPPT algorithm is
implemented .Simulation of the SL-QZSI circuit powered by PV source is carried out by implementing
maximum boost control method and the performance parameters are discussed.
Space Vector of Three Phase Three level Neutral Point Clamped Quasi Z Source ...IJTET Journal
Space vector of three phase three level neutral point clamped quasi z source inverter is proposed in this paper. Space vector modulation is the pulse width modulation consists of number of switching states. Space vector pulse width modulation technique utilizes 15% more power from DC source. Harmonics are reduced by the presence of switching states. Quasi Z-source inverter is advanced topologies which performs both boost and buck operation of a converter. The proposed inverter obtains continuous input current and the boost converter is not needed. So, maximum voltage can be obtained in the load and system complexity is reduced. Maximum power can be obtained from the solar panel by using MPPT. The implementation of MPPT is to operate a PV array under constant voltage and power reference to modify the duty cycle of the inverter.The simulation of proposed topology is done in MATLAB/SIMULINK software.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
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.
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.
Analysis of the Performance of the Drive of the Z source Induction Motor Powe...IJSRED
This document analyzes the performance of a Z-source induction motor powered by a converter. It first provides background on Z-source inverters and their advantages over traditional inverters, including their ability to boost voltage. It then describes the functional principles of a Z-source inverter, including its active states, non-shoot-through zero state, and shoot-through zero state. The document aims to determine parameters of the Z-source inverter like boost factor, output voltages, and voltage gain for maximum constant boost control through simulation and experiments.
Speed Control System for BLDC Motor by using Direct Back EMF Detection Mathodijtsrd
BLDC motors are used in many industrial and traction applications due to high efficiency, low maintenance and high torque. For good performance of BLDC motors, the accurate knowledge of the rotor position is required. The need for the rotor position information in BLDC motors have been satisfied by use of some form of rotor position sensors. But to reduce cost, complexity and also to improve reliability of the system, sensor less drive system is preferred. In this paper, the development of sensor less control system for BLDC motor using a direct back EMF detection method is presented and simulation for proposed system is done with the help of MATLAB SIMULINK. Soe Sandar Aung | Thet Naing Htun "Speed Control System for BLDC Motor by using Direct Back EMF Detection Mathod" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd26624.pdfPaper URL: https://www.ijtsrd.com/engineering/electrical-engineering/26624/speed-control-system-for-bldc-motor-by-using-direct-back-emf-detection-mathod/soe-sandar-aung
This document discusses selective harmonic elimination pulse width modulation (SHEPWM) for multilevel inverters using a generalized Hopfield neural network. It begins with an abstract that introduces multilevel inverters, SHEPWM, and the use of a generalized Hopfield neural network for SHEPWM. It then provides more details on the background and concepts of multilevel inverters, SHEPWM, and the Fourier expansion of the staircase output voltage waveform generated by multilevel inverters. The document focuses on applying SHEPWM to eliminate lower order harmonics from the output waveform using a generalized Hopfield neural network approach.
This document presents a comparative study of five-level and seven-level diode-clamped inverters controlled by space vector pulse width modulation (SVPWM). MATLAB/SIMULINK models of the two inverter topologies were developed. SVPWM control algorithms based on symmetrical sequence were used for each inverter. Both inverters were simulated driving an induction motor. The results showed that the seven-level inverter produced less harmonic distortion and torque fluctuations in the motor, while the five-level inverter had lower commutation losses. The seven-level inverter provided better motor dynamic response.
In this work, an accurate formulation and estimation of stray power losses in induction machines are proposed. Stray losses are estimated by derived formulas based on the leakage fluxes from the induction machine windings. These leakage fluxes induce voltage drops in the machine stator and rotor iron cores and eddy currents in the machine windings, causing stray power losses in the machine iron cores and windings. By adding these losses, a completed estimation of stray losses can be obtained and implemented in the equivalent machine circuit. The stray losses are represented by stray loss resistances connected in series with the stator and rotor circuits. Due to the stray loss in the rotor circuit depending largely on the machine slip this may be omitted without influencing the accuracy of stray loss calculations. The obtained formulas of stray loss estimation are practically satisfied. An accurate loss calculation in induction machines is very useful in the energy-saving issue.
Cascaded h bridge multilevel inverter in a three phase eleven leveleSAT Journals
Abstract
This paper essentially concentrates on the design and implementation of a unique topology for a three phase eleven level
cascaded H-bridge multilevel cluverter by employing different kinds of switching schemes. The basic purpose of this paper is to
enhance the number of voltage level at the output without addition of any complexity to power circuit.
The main advantages of this proposed topology is to scale down the THD and reducing electromagnetic interface EMI generation
and high voltage with very close to sine waveform. In this paper, severel kinds of carrier pulse width modulation techniques are
proposed as which scale down the total harmonic distortion and improve the out voltage from the proposed topology and POD
modulation techniques reduce the THD. A number of H-bridge arranged in cascaded to increase the voltage level with the
different switching schemes analyzed in this paper. It is observed that this new topology can be recommended to three phase
eleven level cascaded H-bridge inverter for the best and optimum performance over the conventional methods. This performance
in optimized in the eleven level of inverter.
Improving the fundamental waveforms and reducing the total harmonic distortion by using 60 IGBTs and switching is arranged
by a topology in cascaded manners.
The simulation model is produced by MATLAB2009 software version.
Key Words: Cascaded H-bridge multilevel inverter, different phase pulse width modulation, total harmonic
distortionTHD, EMI
This document summarizes key concepts about three-phase systems. It defines a three-phase system as having three sinusoidal voltages differing in phase by 120 degrees. The voltages can form a positive or negative sequence. Three-phase systems are commonly used for power generation, transmission, and distribution due to their ability to transmit more power with less material. Formulas are provided for calculating line voltages, currents, and power in balanced and unbalanced three-phase systems. Advantages of three-phase systems like constant torque and easier starting of motors are also discussed.
Comparative Evaluation of Generalized Multicell Impedance Source Inverter for...IJPEDS-IAES
Voltage-Source Inverter is limited by its only voltage step-down operation. In adding with extra boosting the flexibility is kept active for the number of semiconductors which is unchanged, voltage-type Z-source inverter was earlier proposed. This new class of inverter is generally less sensitive to electromagnetic noises. However, their boosting capabilities are anyhow less with high component stresses and poorer spectral performances caused by low modulation index ratios. Their boosting gains are, therefore, restricted in practice. To overcome these we use the generalized switched-inductor Z- source inverter is proposed, By comparing with PWM technique and SPWM technique, whose extra boosting abilities and other advantages have been verified in simulation analysis and experiment.
Distance Algorithm for Transmission Line with Mid-Point Connected STATCOMIRJET Journal
This document presents an adaptive zone selection algorithm for distance protection of a transmission line with a midpoint connected STATCOM device. The algorithm aims to address challenges to distance protection posed by the presence of the STATCOM. It investigates the impact of the STATCOM on apparent impedance seen by distance relays under different fault conditions using EMTDC/PSCAD software. An adaptive setting is proposed that calculates a new reach based on system and STATCOM parameters to ensure proper operation of distance relays for both underreach and overreach scenarios. The performance of the proposed adaptive algorithm is evaluated through simulations of various single line to ground and three phase fault cases with different fault locations, resistances and system load angles.
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.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
This paper proposes the use of Embedded EZ-source
inverter system (EZSI) as a single stage power conversion
concept for adjustable speed drives (ASD) in photovoltaic
applications. Open loop and closed loop control strategy of
EZSI system are proposed. EZSI produces the same voltage
gain as Z-source inverter (ZSI) but due to the DC sources
embedded within the X- shaped impedance network, it has
the added advantage of inherent source filtering capability
and also reduced capacitor sizing. This is attained without
any extra passive filters. By controlling the shoot-through
duty ratio and modulation index, EZSI system can produce
any desired AC output voltage even greater than DC rail
voltage and it also provides ride-through capability under
voltage sag. These advantages are more significant for
adjustable speed drive (ASD) applications in order to regulate
the speed. The operational analysis, control strategy and
simulation results exemplify that an EZSI is the most
promising technique for renewable energy applications in
order to reduce the overall system complexity and thereby
improving the inverter efficiency.
Cascaded h bridge multilevel inverter for induction motor driveseSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Efficiency Optimized Brushless DC Motor Drive based on Input Current Harmonic...IJPEDS-IAES
This paper describes efficiency improvement of a position sensorless
brushless dc motor with improved pulse width modulation scheme for the
inverter compared to existing ones. This is based on Selective Harmonic
Elimination. The proposed method reduces Total Harmonic Distortion from
the input current and armature flux and thereby reducing the core losses.
Also the power requirement with the proposed switching technique is much
lesser than the existing switching scheme. The effectiveness of the proposed scheme is demonstrated through simulation and experimental results.
Induction Motors Faults Detection Based on Instantaneous Power Spectrum Analy...IDES Editor
A method of induction motor diagnostics based on
the analysis of three-phase instantaneous power spectra has
been offered. Its implementation requires recalculation of
induction motor voltages, aiming at exclusion from induction
motor instantaneous three-phase power signal the component
caused by supply mains dissymmetry and unsinusoidality. The
recalculation is made according to the motor known
electromagnetic parameters, taking into account the
electromotive force induced in stator winding by rotor currents.
The results of instantaneous power parameters computation
proved efficiency of this method in case of supply mains voltage
dissymmetry up to 20%. The offered method has been tested
by experiments. Its applicability for detection of several stator
and rotor winding defects appeared in motor simultaneously
has been proved. This method also makes it possible to
estimate the extent of defects development according to the
size of amplitudes of corresponding harmonics in the spectrum
of total three phase power signal.
This document contains 20 multiple choice questions from GATE EE 2007 exam. It provides the questions, solutions and explanations for each question in detail. The key details are:
- The document contains one mark multiple choice questions on topics like transistors, voltage regulators, transformer connections, generator scheduling, HVDC systems, electric field distribution, op-amps, system stability, time variant systems, sampling, matrix rank, thyristor converters etc.
- For each question, the solutions clearly explain the concepts and calculations involved in arriving at the correct option. Relevant circuit diagrams and equations are included.
- The level of detail in the solutions and explanations is quite high as it is aimed to help students prepare for competitive exams
This document contains abstracts for several IEEE 2012 MATLAB projects related to power quality and control of power electronics systems. The abstracts discuss active power filters, voltage regulation techniques, induction motor drives, microgrids, and fuel cell energy systems. Simulation results were obtained using MATLAB/Simulink software.
Simulation of Z-Source Inverter Fed Three Phase Induction Motor DriveIJSRD
This paper presents performance characteristics of Z-source inverter (ZSI) fed Induction Motor (IM) drives. Z-Source inverter is a single stage converter which performs both buck-boost energy conversions using the LC impedance network. This reduces the voltage range of the capacitors used and also the cost of the proposed topology which is in turn used to control the speed of an induction motor which is used in many valuable industrial applications. The Z Source inverter is a combined inverter with an additional buck-boost feature and the proposed topology increases the efficiency of the circuit by reducing the voltage stress across the capacitors. The z-source inverter is very advantageous over traditional inverters and we can be employed all ac and dc power conversion applications. Z-source inverter can boost dc input voltage with no requirement of dc to dc boost converter or step up transformer hence overcoming output voltage limitation of voltage source inverter as well as lower cost. A comparison among conventional PWM inverter dc to dc boost PWM inverter and control circuit cost which are the main a power electronics system.
Three Phase Fault Analysis With Auto Reset On Temporary Fault And Permanent TripEdgefxkits & Solutions
This PPT explains about Three phase fault analysis. This is achieved by using star to delta conversions.
Edgefxkits.com has a wide range of electronic projects ideas that are primarily helpful for ECE, EEE and EIE students and the ideas can be applied for real life purposes as well.
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The document lists 97 electrical projects for engineering students on the website http://www.edgefxkits.com. The projects cover a wide range of topics and involve using components like Arduino, PIC microcontrollers, sensors and more. They include projects involving solar energy systems, motor speed control, wireless power transfer, home automation and electrical load management. The conclusion states that students can gain theoretical and practical knowledge from these projects by choosing ones that interest them.
Current Source Inverter and Voltage Source Inverter Sadanand Purohit
The document discusses two types of inverters - current source inverters (CSI) and voltage source inverters (VSI). It describes the construction and working of CSI, which uses predetermined source current and load impedance to determine output voltage. VSI uses a constant DC input voltage and feedback diodes. The document also covers applications of CSI and VSI, such as use of CSI for AC motor drives due to regenerative capability, and use of VSI in UPS and AC drives. FACTS devices based on VSI are also summarized, including STATCOM, SSSC and UPFC for controlling transmission line parameters.
DIRECT TORQUE CONTROL OF THREE PHASE INDUCTION MOTOR USING FOUR SWITCH THREE ...smadhumitha
This document discusses direct torque control of a three-phase induction motor using a four-switch inverter. It begins by reviewing existing literature on direct torque control methods and their limitations. The author then proposes using direct torque control with space vector modulation to control a four-switch inverter for improved dynamic response, reduced torque ripple, and lower harmonic distortion compared to existing methods. Simulation and hardware results demonstrate the benefits of the proposed method, such as lower torque ripple and current harmonic distortion.
This document provides information on inverters, including:
- Inverters convert DC input voltage into AC output voltage of desired magnitude and frequency. They are also known as DC-AC converters.
- Inverters can be classified as single-phase or three-phase, and by the type of switching device used (BJT, MOSFET, IGBT, GTO).
- Applications include variable speed AC motors, induction heating, UPS systems. Inputs can be batteries, fuel cells, solar cells.
- Circuit diagrams and operating principles are provided for single-phase half-bridge, full-bridge, and three-phase inverters using 1800 and 1200 conduction modes.
The document describes how to conduct short circuit and open circuit tests on transformers using a DPATT-3Bi device to measure copper and iron losses, respectively. It provides details on the test setups, calculations for full load current and no load current, and how to interpret the results displayed on the DPATT-3Bi screen. The document also lists standard limits for transformer impedance voltages and losses according to Indian standards.
This document presents a neural network predictive controller for three phase inverter fed induction motor speed control. A neural network predictive controller is designed to control the motor speed by varying its reference value and regulating the motor speed. Simulation results show the performance of the induction motor drive during step changes in speed and load torque with the neural network predictive controller, with lower current ripple and reduced torque ripple compared to other controllers. The performance of the neural network predictive controller is evaluated using integral absolute error and integral time-weighted absolute error metrics.
This document provides instructions for identifying the leads of various transistor types and testing transistors with an ohmmeter to determine if they are good or defective. It describes several methods for identifying the emitter, base, and collector leads based on the transistor packaging and markings. It also outlines three tests to perform with an ohmmeter: forward bias tests of the base-emitter and base-collector junctions, and a leakage current test between the emitter and collector. The results of these tests can indicate whether a transistor is good or defective.
Modified T-type topology of three-phase multi-level inverter for photovoltaic...IJECEIAES
In this article, a three-phase multilevel neutral-point-clamped inverter with a modified t-type structure of switches is proposed. A pulse width modulation (PWM) scheme of the proposed inverter is also developed. The proposed topology of the multilevel inverter has the advantage of being simple, on the one hand since it does contain only semiconductors in reduced number (corresponding to the number of required voltage levels), and no other components such as switching or flying capacitors, and on the other hand, the control scheme is much simpler and more suitable for variable frequency and voltage control. The performances of this inverter are analyzed through simulations carried out in the MATLAB/Simulink environment on a threephase inverter with 9 levels. In all simulations, the proposed topology is connected with R-load or RL-load without any output filter.
The Nine-Switch Inverter(NSI) is a recently developed dual output converter. It can be used to drive two three-phase loads independently. As a substitute to two separate conventional voltage source inverters, the NSI has been, already, proposed in various industrial applications to reduce the numberof semiconductor switches and its associated energy losses and drive circuitry. On the other hand, the Direct Torque Control(DTC) is a robust control scheme of AC motors, which consist of selecting proper state vectors of a conventional voltage source inverter. The NSI, having a different working principle from the conventional voltage source inverter and taking into account the varying influence of active space vectors on motor’s torque and stator flux, a Direct Torque Control is suggested in this paper to, efficiently, drive two induction motors independently, while minimizing the torque and stator flux ripples of both motors. Simulations results confirm the effectiveness of the proposed algorithm. In addition, application of this newly proposed control scheme in operation of an Electric Vehicule (EV) is demonstrated.
In the proposed approach,instead of a conventional 3- Phase inverter a component minimized single pha se inverter is utilized which reduces the cost of the inverter,th e switching losses,and the complexity of interface circuits to generate logic signals. A performance comparison of the prop osed inverter fed drive with a conventional 3Phase inverter fed drive is also mode in terms of speed response and t otal harmonic distortion (THD) of the stator curren t. The proposed inverter fed IM drive is found acceptable consideri ng its cost reduction and other advantageous featur es. A general pulse width modulation (PWM) method for c ontrol of 1-phase inverters is presented. The vecto r PWM offers a simple method to select three or four vectors tha t effectively synthesize the desired output voltage,even in presence of voltage oscillations across the two dc-link capacit ors. The influence of different switching patterns on output voltage symmetry,current waveform,switching frequency and common mode voltage can be examined. The paper als o discusses how the use of the wye and delta connecti ons of the motor windings affects the implementatio n of the pulse width modulator.
This document summarizes the performance analysis of an indirect rotor field orientation control scheme for a five-phase induction motor driven by an eight-switch inverter topology. The proposed inverter uses only eight switches compared to the traditional ten-switch design, reducing cost and improving reliability. Simulation models of the proposed drive system and a classical ten-switch design were developed in Matlab/Simulink. Simulation results showed similar performance between the two inverter designs over a range of motor speeds and loads, but the DC voltage of the eight-switch inverter must be higher to achieve the same performance across all operating conditions.
In this paper a new, simple multilevel inverter topology is proposed. Multilevel inverter uses several dc sources and power switches to synthesize desired output voltage waveform. The single phase structure of proposed topology in this paper consists of two dc sources and eight power switches. When the magnitudes of dc sources are equal it operates in symmetric mode, however in order to increase output voltage levels unequal magnitudes of dc sources are selected, then it operates in asymmetric mode. So far, multilevel inverter topologies have been used in motor drive industry to run induction motors. Recently permanent magnet synchronous motors (PMSM) are replacing induction motors. Multilevel inverter is an attracting choice for driving high performance PMSM. However very few studies discuss the performance of multilevel inverter fed PMSM. In this paper simulation of novel symmetric and asymmetric multilevel inverter is carried out to analyze performance of PMSM. The topology is investigated through computer simulation using MATLAB/Simulink.
Application of SVM Technique for Three Phase Three Leg Ac/Ac Converter TopologyIOSR Journals
This paper presents a simulation of a three-phase three-leg AC/AC converter topology using nine IGBTs and space vector pulse width modulation (SVM) technique. The proposed topology reduces the number of switches compared to conventional back-to-back and matrix converters. Simulation results show the converter provides sinusoidal input and output voltages with unity power factor under constant frequency and variable frequency operation. Experimental results from a 5kVA prototype verify the validity of the proposed scheme.
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.
Dynamic model of A DC-DC quasi-Z-source converter (q-ZSC)IJECEIAES
Two quasi-Z-source DC-DC converters (q-ZSCs) with buck-boost converter gain were recently proposed. The converters have advantages of continuous gain curve, higher gain magnitude and buck-boost operation at efficient duty ratio range when compared with existing q-ZSCs. Accurate dynamic models of these converters are needed for global and detailed overview by understanding their operation limits and effects of components sizes. A dynamic model of one of these converters is proposed here by first deriving the gain equation, state equations and state space model. A generalized small signal model was also derived before localizing it to this topology. The transfer functions (TF) were all derived, the poles and zeros analyzed with the boundaries for stable operations presented and discussed. Some of the findings include existence of right-hand plane (RHP) zero in the duty ratio to output capacitor voltage TF. This is common to the Z-source and quasi-Z-source topologies and implies control limitations. Parasitic resistances of the capacitors and inductors affect the nature and positions of the poles and zeros. It was also found and verified that rather than symmetric components, use of carefully selected smaller asymmetric components L1 and C1 produces less parasitic voltage drop, higher output voltage and current under the same conditions, thus better efficiency and performance at reduced cost, size and weight.
This document presents a performance analysis of a two-phase induction motor fed by a four-leg voltage source inverter for low power applications. A mathematical model of the two-phase induction motor is developed using MATLAB to simulate speed variation under different load torques. A four-leg voltage source inverter is proposed to generate the two-phase output voltage using sinusoidal pulse width modulation for its superior DC utilization and lower total harmonic distortion compared to a three-leg inverter. Simulation results show the speed-torque characteristics of the two-phase induction motor fed by the four-leg inverter for validating its suitability for low power applications below 2.5 kW.
IRJET- A Review on Three-Phase to Seven-Phase Power Converter using TransformerIRJET Journal
This document proposes and discusses a technique to generate a seven-phase power supply from a standard three-phase supply using a special transformer connection scheme. The transformer has three iron cores each with one primary and multiple secondary coils. By connecting the secondary coils in a specific configuration based on turn ratios, a seven-phase star output is obtained where each phase is 51.43 degrees out of phase. This technique allows generation of a pure sinusoidal seven-phase voltage that can be used for multiphase motor testing or in seven-phase power transmission and rectifier systems. Mathematical analysis is provided to derive the turn ratios needed to produce the seven evenly spaced phases from the three input phases.
11.vector control of wind driven self excited induction generator connected t...Alexander Decker
This document summarizes a research paper that proposes a 24-pulse AC-DC converter system for a vector-controlled self-excited induction generator connected to the power grid. The system aims to improve power quality by reducing harmonic distortion. It uses an autotransformer-based rectifier with reduced rating magnetics and a pulse doubling technique. Simulation results in MATLAB/Simulink show the system is able to eliminate harmonics up to the 21st order and achieve near unity power factor over a wide operating range, with minimal effects observed from load variations. Transient responses during startup, load application, and short circuit events demonstrate the effectiveness of the proposed AC-DC converter design.
Vector control of wind driven self excited induction generator connected to g...Alexander Decker
The document describes a system for controlling a wind-driven self-excited induction generator connected to the grid using a 24-pulse AC-DC converter with pulse doubling technique. The system aims to improve power quality indices. A model of the system is developed in MATLAB/Simulink using a 3.5kW induction generator, 24-pulse diode bridge rectifier, and grid connection. Stator flux orientation control is used to regulate the generator voltage and frequency. Simulation results are presented to analyze the effectiveness of the proposed AC-DC converter under varying load conditions on the induction generator.
Small Signal Modeling Of Controller For Statcom Used In Distribution System F...IJERA Editor
This document presents a small signal model of a STATCOM (Static Synchronous Compensator) used for reactive power management in a distribution system. A PI controller is designed for the reactive current component of the STATCOM. The model linearizes the nonlinear STATCOM model and performs small signal modeling of the phase angle and modulation index. Simulation results in MATLAB/Simulink show the model with PI controllers can improve the power factor of the grid current for linear inductive loads by adjusting the reactive power output of the STATCOM.
dSPACE Implementation for a Fuzzy Logic Voltage Control using a Self-Excited ...IJECEIAES
This document describes a study that implements fuzzy logic voltage control using a self-excited induction generator and voltage source inverter. A dSPACE board is used to compare simulation and experimental results. The system aims to maintain a constant RMS voltage output despite variable speed and load conditions from the generator. Simulation results show that a fuzzy logic PI controller regulating a sinusoidal pulse width modulation switching scheme is effective at keeping the output voltage at 220Vrms with minimal distortion during changes in rotor speed from 1000rpm to 1200rpm and load variations from 500W to 1KW. Experimental testing using the dSPACE board validated the effectiveness of the proposed control approach.
This paper presents an analytical comparison between two-level inverter and three-level neutral point diode clamped inverters for electric vehicle traction purposes. The main objective of the research is to declare the main differences in the performance of the two inverter schemes in terms of the switching and conduction losses over an entire domain of the modulation index and the phase angle distribution, steady-state operation, transient operation at a wide range of speed variation, and the total harmonic distortion THD% of the line voltage output waveform. It also declares the analysis of the three-level neutral point diode clamped inverter (NPCI) obstacle and the unbalance of the DC-link capacitor voltages. The introduced scheme presents an Induction Motor (IM) drive for electric vehicle (EV) applications. Considering the dynamic operation of the EV, the speed of the three-phase induction motor is controlled using a scalar V/Hz control for the full range of the IM power factor (PF). A comprehensive MATLAB/Simulink model for the proposed scheme is established.
Analysis Approach for Five Phase Two-Level Voltage Source Inverter with PWM T...ijsrd.com
this paper gives idea of comparison of five phase two-level voltage inverter (FPTLVSI) without filter circuit and control scheme and FPTLVSI with filter circuit and PWM control scheme for induction motor drive. The paper demonstrates using mat lab simulations about comparison in term of harmonics analysis for different firing angles and find best angle suitable for output with minimum harmonics for FPTLVSI without filter circuit and control scheme and harmonics analysis of FPTLVSI with filter and PWM control scheme. This paper suggests simulation of comparison of harmonics point of view five phase two-level voltage inverter (FPTLVSI) without filter circuit and control scheme and with filter circuit and PWM control scheme for induction motor drive.
Single Phase Thirteen-Level Inverter using Seven Switches for Photovoltaic sy...Editor IJMTER
This paper proposes a single-phase thirteen-level inverter using seven switches, with a
novel pulse width-modulated (PWM) control scheme. The Proposed multilevel inverter output
voltage level increasing by using less number of switches driven by the multicarrier modulation
techniques. The inverter is capable of producing thirteen levels of output-voltage (Vdc, 5/6Vdc,
4/6Vdc, 3/6Vdc, 2/6Vdc, 1/6Vdc, 0, -5/6Vdc, -4/6Vdc, -3/6Vdc, -2/6Vdc, -1/6Vdc,-Vdc) from the
dc supply voltage. A digital multi carrier PWM algorithm was implemented in a Spartan 3E FPGA.
The proposed system was verified through simulation and implemented in a prototype.
A Review on Performance Analysis of Matrix Converter Fed AC Motor DriveIAES-IJPEDS
This paper presents a review on the analysis of characteristics that determines
the performance of the Matrix Converter (MC) fed AC motor drive. Review
is made based on the analysis of the different characteristics achieved in the
literature. Different characteristic parameters considered in this paper are
total harmonic distortion, common mode voltage, voltage transfer ratio and
efficiency. Comparison and analysis of these characteristic parameters is
done based on various semi conductor switches, topology, and control and modulation techniques.
Design & Simulation Of 3-Phase, 15-Level Inverter with Reverse Voltage TopologyIJERA Editor
This document describes the design and simulation of a 15-level three-phase inverter with a reverse voltage topology. A new topology is proposed that requires fewer components than existing inverters, particularly at higher voltage levels. This reduces complexity. The 15-level inverter is modeled and simulated in MATLAB. Simulation results show the output voltage waveform, total harmonic distortion within reasonable limits, and voltage and current waveforms. The proposed inverter provides high voltage output with reduced harmonic distortion and lower component count.
Direct torque control of IM using PID controller IJECEIAES
Direct torque control "DTC" technique is one of a high performance control system of an AC motor drive, which was proposed after the vector oriented control scheme during the resent 25 years. It has been developed rapidly for its concise system scheme, transient and dynamic performance. The DTC mechanism consists of voltage vector selection table, two hysteresis comparators and two estimator’s one for stator flux and another for electromagnetic torque. DTC is directly control torque and flux by using Voltage Source Inverter VSI, space vector and stator flux orientation and indirect speed regulated. A several control techniques can be used for improving the torque and flux performance. In this paper, the DTC with Proportional-Integral-Derivative (PID) controller used to improve the starting and dynamic performance of asynchronous motor AM, which gives good torque and flux response, best speed control and also minimize the unacceptable torque ripple. The mathematical model of DTC with PID controller of 3-phase induction motor IM are simulated under MatlabSimulink. Therefore, the DTC based on PID controller has good performance of IM compared to classical DTC for starting, running state and also during change in load.
Similar to 11.modeling, analysis and control of hexagram inverter for three phase induction motor drive (20)
Abnormalities of hormones and inflammatory cytokines in women affected with p...Alexander Decker
Women with polycystic ovary syndrome (PCOS) have elevated levels of hormones like luteinizing hormone and testosterone, as well as higher levels of insulin and insulin resistance compared to healthy women. They also have increased levels of inflammatory markers like C-reactive protein, interleukin-6, and leptin. This study found these abnormalities in the hormones and inflammatory cytokines of women with PCOS ages 23-40, indicating that hormone imbalances associated with insulin resistance and elevated inflammatory markers may worsen infertility in women with PCOS.
A usability evaluation framework for b2 c e commerce websitesAlexander Decker
This document presents a framework for evaluating the usability of B2C e-commerce websites. It involves user testing methods like usability testing and interviews to identify usability problems in areas like navigation, design, purchasing processes, and customer service. The framework specifies goals for the evaluation, determines which website aspects to evaluate, and identifies target users. It then describes collecting data through user testing and analyzing the results to identify usability problems and suggest improvements.
A universal model for managing the marketing executives in nigerian banksAlexander Decker
This document discusses a study that aimed to synthesize motivation theories into a universal model for managing marketing executives in Nigerian banks. The study was guided by Maslow and McGregor's theories. A sample of 303 marketing executives was used. The results showed that managers will be most effective at motivating marketing executives if they consider individual needs and create challenging but attainable goals. The emerged model suggests managers should provide job satisfaction by tailoring assignments to abilities and monitoring performance with feedback. This addresses confusion faced by Nigerian bank managers in determining effective motivation strategies.
A unique common fixed point theorems in generalized dAlexander Decker
This document presents definitions and properties related to generalized D*-metric spaces and establishes some common fixed point theorems for contractive type mappings in these spaces. It begins by introducing D*-metric spaces and generalized D*-metric spaces, defines concepts like convergence and Cauchy sequences. It presents lemmas showing the uniqueness of limits in these spaces and the equivalence of different definitions of convergence. The goal of the paper is then stated as obtaining a unique common fixed point theorem for generalized D*-metric spaces.
A trends of salmonella and antibiotic resistanceAlexander Decker
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11.modeling, analysis and control of hexagram inverter for three phase induction motor drive
1. Control Theory and Informatics www.iiste.org
ISSN 2224-5774 (print) ISSN 2225-0492 (online)
Vol 1, No.1, 2011
Modeling, Analysis and Control of Hexagram Inverter for Three-
Phase Induction Motor Drive
K.Rajambal
Department of Electrical and Electronics Engineering
Pondicherry Engineering College, Pondicherry, India
E-mail: rajambalk@gmail.com
G.Renukadevi
Department of Electrical and Electronics Engineering
Pondicherry Engineering College, Pondicherry, India
E-mail: renunila_1977@yahoo.com
Abstract
This paper presents the modeling, analysis and control of Hexagram inverter for three phase induction motor
drive configuration. The Hexagram inverter can be used for both three phase and six phase applications. It has
many advantages including reduced number of switches, modular structure leading to easy construction and
maintenance, isolated dc buses. Besides, it has built-in fault redundancy due to the module interconnection. It
has lowered dc energy storage requirement compared to that of cascaded H-bridge inverter. This eminent feature
makes the system in high power applications. A simulation model of the Hexagram inverter fed three phase
induction motor drive is developed in Matlab/Simulink environment. Simulation is carried out to study the drive
performance at different operating conditions and the results are presented.
Keywords: closed loop control, fault tolerant feature, hexagram inverter, three phase induction motor drive
1. Introduction
The medium-voltage (MV) converters have become a new breed in high-power applications. Numerous MV
topologies have been proposed and investigated since the mid 1980s (Jose Rodriguez 2002 - Krug 2004). The
development and application of MV variable speed drives (VSDs) have brought significant advantages in
improved process control, higher efficiency, and energy savings to the industry (Cheng 2006). From the survey
articles (Carrasco 2006 - Kim 2004) it becomes clear that three topologies are favored by MV drive
manufacturers: Neutral-point-clamped (NPC) inverter (Bendre 2006-Vargas 2007); Flying capacitor (FC)
inverter (Kim 2004); and cascaded H-bridge (CHB) inverter (Du 2006 - Rech 2007). A high-voltage fast
recovery diode is used to clamp the voltage in NPC configuration. The configuration suffers from voltage
unbalancing, neutral point stabilization at heavy or dynamic loading, higher THD and the requirement of LC
filter to reduce the vibration and noise of the machine. The FC configuration is used to clamp the voltage and
overcome some of the drawbacks of NPC configuration. However the number of capacitors required increases,
when the number of levels is high and complex precharge circuits are needed (Kim 2004). At present, the
cascaded H-bridge inverter is the best-selling product in the MV ASD market worldwide (Robicon). With the
modular structure, the cascaded H-bridge inverter is easy to construction and maintenance. And with the
separate dc buses, there is no voltage unbalancing problem. However, despite its many advantages, the cascaded
H-bridge inverter still suffers from following drawbacks (Cengelci 1999). It employs a large number of single-
phase inverter modules, isolated secondary windings in the input transformer, and three-phase diode rectifiers,
resulting in high manufacturing cost. The dc-bus capacitive energy storage requirement is high due to the single-
phase structure. It does not have built-in fault tolerant feature so that additional inverter modules are necessary
to provide redundancy. The problems can be overcome by a new multilevel inverter – Hexagram inverter (Wen
&.Smedley). The structure of the Hexagram inverter is shown in Figure 1 (a). The new topology is composed of
six interconnected VSIs in the form of six switch module as shown in the circle in Figure 1 (b). The connection
between the modules is depicted with a connection diagram.
There are six inner inductors connecting any of the two modules in order to limit the circulating current. With
synchronized control signals, small value inductors will be sufficient to limit the circulating current to a low
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value. Figure 1(c) shows the connection diagram, in which each triangle specifies the each inverter bridge and
the inner legs any two of the VSI modules interconnected to the inductors, and the outer legs are connected with
motor terminals. Differing to the three-phase VSI, the Hexagram inverter has six output terminals, which
provides two options to either drive a three-phase motor (neutral not connected) or drive a six-phase motor. This
paper will focus on the Hexagram inverter applied for a three-phase motor drive (Wen & Smedley 2008) and the
star connected six phase drive (Wen & Smedley 2007). The new Hexagram inverter has a modular structure and
no voltage balancing concern as the cascaded H-bridge inverter; in addition, it has following superior
characteristics:
• Fewer diode bridge rectifiers, inverter modules, and input transformer secondary windings are
required to achieve the power level.
• Lower dc-link capacitive energy storage requirement due to the three-phase structure. In balanced
systems, the instantaneous power of each six-switch module is constant so that the capacitors are not
subject to low-frequency power ripples.
• Due to the interconnected structure, Hexagram inverter has built-in redundancy for fault tolerance.
The inner legs of the Hexagram inverter which are not directly connected to the load are connected in
a closed-loop. Therefore, if some switch of the inner leg fails (open), the overall inverter is capable of
operating at a reduced power level.
• The voltage stress of this inverter is reduced three times compared to a two-level inverter with the
same output voltage.
In addition, well developed Indirect field oriented control schemes and well developed SPWM techniques for
VSI can be directly applied, and the six modules inside Hexagram inverter equally share the output power so
that the components of the inverter no need to be over designed. With the symmetrical and naturally balanced
structure, the proposed Hexagram inverter has many inherent advantages. Detailed analysis of the inverter will
be conducted in section 2 to section 6, after that simulation and experiment results will be given to verify the
analysis in section 7 and 8, then a brief conclusion will be provided in section 9.
2. Hexagram Inverter for a Three Phase Induction Motor Drive
Figure 2 shows a complete MV ASD system, composed of a transformer with six secondary windings, six diode
rectifiers, six dc capacitors and a Hexagram inverter (Wen & Smedley 2008). The transformer shown is an 18-
pulse transformer, with six Secondary windings arranged in 0°, ±20° phase shift (two are identical), to achieve
harmonic current cancellation in the utility line currents, leading to clean input power. The input current total
harmonic distortion (THD) for 18-pulse rectifier is about 5-6%. The six secondary windings can also be
arranged in ±5°, ±15°, ±25° phase shift to form a 36-pulse rectifier to further reduce the input current
harmonics, if necessary. Diode rectifiers and dc capacitors are used to convert the three-phase ac to dc to
provide the isolated dc buses for the Hexagram inverter. Replacing the diode rectifiers with the pulse width
modulation (PWM) voltage source converters will enable the VSD system with the capability of regenerative
braking (Wen &.Smedley 2008).
3. Analysis of Hexagram Inverter
3.1 Voltage Relationship
The phasor diagram of the VSI module of Hexagram inverter is shown in Figure 3. Phase Voltages of VSI
modules are shown in Figure 3 (a). It is seen that the phase of the VSI module is V volts whereas the output
voltage is 3V for Hexagram inverter as shown in Figure 3 (b).The rms phase voltages of the VSI modules are
given in equation(1).
va1o1 va3o3 va5o5 va2o2 va4o4 va6o6
v = v = v =−v =−v =−v
b1o1 b3o3 b5o5 b2o2 b4o4 b6o6 (1)
vc1o1 vc3o3 vc5o5 vc2o2 vc4o4 vc6o6
Where ω is the frequency of the voltage in radius. (It should be noted that (1) is true with restrictions on the
modulation strategy. For example, for sinusoidal pulse width modulation (SPWM), the switching frequency
should be an integer multiple of six times the fundamental frequency). Then, the fundamental output voltages of
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Vol 1, No.1, 2011
the Hexagram inverter are determined and given in the equation (2).
v AO v A 'O 3 2V sin( ω t )
v = − v = 3 2V sin( ω t − 120 ° ) (2)
BO B 'O
vCO
v C ' O 3 2V sin( ω t + 120 ° )
From the equation (2) the output voltage of Hexagram inverter are three times of the VSI modules.
3.2 Current Relationship
Assume that the Hexagram inverter is connected to a symmetrical three-phase load. According to (2), the
three-phase output currents can be expressed as
iA ia1 iA' ia 4 2I sin(ωt )
i = i = − i = − i = 2I sin(ωt − 120°) (3)
B b3 B' b6
iC ic5 iC ' ic 2
2I sin(ωt + 120°)
The phase currents of the six VSI modules satisfy the following equation:
ia 1 + ib 1 + ic1
ia 2 + ib 2 + ic 2
ia 3 + ib 3 + ic 3
=0 (4)
ia 4 + ib 4 + ic 4
ia 5 + ib 5 + ic 5
ia 6 + ib 6 + ic 6
Any two of the six modules are interconnected so that the currents inside the inverter have the following
relationship:
ib1 ib 2
i i
a2 a3
ic 3 ic 4
= − (5)
ib 4 ib 5
ia 5 ia 6
ic 6
ic1
With the inductors, the circulating current in the loop formed by the connection of the six modules is limited to a
low value and can be neglected as
ib 1 + i a 2 + ic 3 + ib 4 + i a 5 + ic 6 = 0 (6)
Combining (3)–(6), gives the result that module 1, 3, 5 have the same phase currents as iA, iB, iC, and module 2,
4, 6 have the same phase currents as –iA, -iB, -iC. The result is expressed in equation (7) and (8).
ia 1 ia 3 ia 5 2 I s in ( ω t )
i = i = i =
2 I s in ( ω t − 1 2 0 ° ) (7)
b1 b3 b5
ic1 ic 3 ic 5
2 I s in ( ω t + 1 2 0 ° )
ia 2 ia 4 ia 6 2 I s in ( ω t − 1 8 0 °)
i = i = i = 2 I s in ( ω t + 6 0 °)
(8)
b2 b4 b6
ic 2 ic 4 ic 6
2 I s in ( ω t − 6 0 °)
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Vol 1, No.1, 2011
This result indicates that when the Hexagram inverter is connected to a symmetrical load, the phase currents of
all six modules are identical. The current phasor diagram is depicted in Figure 4. Where the currents lagging the
corresponding voltages by θ degree. The phase angle θ is dependent on the load characteristics.The
instantaneous power of the six modules is derived from (2) and (8) as
p I ( t ) = p II ( t ) = p III ( t ) = p IV ( t ) = p V ( t ) = p V I ( t ) = 3V I co s θ (9)
This result indicates that the six modules have equal output power, and the instantaneous power through each
module is constant, so that the dc energy storage requirement is low and the dc capacitor can be sized small.
4. Equivalent Circuit of the Hexagram Inverter
The equivalent circuit of the circulating current loop is depicted in Figure 5.where L12, L23, L34, L45, L56 and L61
are the inductances of the inductors between any two of the six modules; Vb1c1, Va2b2, Vc3a3, Vb4c4, Va5b5 and Vc6a6
are the instantaneous voltages depending upon the switching of the inverter, and iL12, iL23, iL34, iL45, iL56 and iL61
are the inductor currents derived under the zero circulating current condition and satisfy the following equation:
iL12 ib1 ib 3
i i i
L 23 a 2 a 4
iL 34 ic 3 ic 5
= = (10)
iL 45 ib 4 ib 6
iL 56 ia 5 ia1
iL 61 ic 6 ic 2
The loop voltage defined as the summation of the equivalent voltage sources in the circulating current loop is
calculated as given in equation (11)
diL12 di di di di di
vloop = vb1c2 + va2b2 + vc3a3 + vb4c4 + va5b5 + vc6a6 + L12
+ L23 L23 + L34 L34 + L45 L45 + L56 L56 + L61 L61 (11)
dt dt dt dt dt dt
The circulating current will occur when the loop voltage is not zero. Moreover, the inductor currents can be
viewed as the summation of the currents derived at the zero circulating current condition as given in equation
(10) and the circulating current is
i 'L12 iL12
i ' i
L 23 L 23
i 'L 34 iL 34
= + i lo o p (12)
i 'L 45 iL 45
i 'L 56 iL 56
i 'L 61
iL 61
In equation (11), (Vb1c1+Va2b2+Vc3a3+Vb4c4+Va5b5+Vc6a6) is the major part, since the rest of the part equals 0 at the
equal inductance condition according to (9) and (11); even if not, it is small due to the small inductances. In the
ideal situations (Vb1c1+Va2b2+Vc3a3+Vb4c4+Va5b5+Vc6a6) equals 0 as well. However, both unmatched switching
and unequal dc buses will cause it to be nonzero and result in the occurrence of the circulating current. The
unmatched switching has very short time duration; small inductances such as several micro henrys are sufficient
to limit the circulating current. Consequently, the unequal dc bus is the major cause of the circulating current.
By having the first and fourth secondary windings of the transformer of the same phase angle, so are the third
and sixth, and fifth and second; the unequal dc bus condition caused by the ripple voltages of the rectification
will be entirely eliminated.
5. Closed Loop Control of Hexagram Inverter
The vector control of ac drives has been widely used in high performance control system. Indirect field oriented
control (IFOC) is one of the most effective vector control of induction motor due to the simplicity of designing
and construction. In order to obtain the high performance of torque and speed of an IM drive, the rotor flux and
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torque generating current components of stator current must be decoupled suitably respective to the rotor flux
vector like separately excited dc motor. Figure 6 shows the complete schematic of indirect field oriented control
for induction motor drive. The torque command is generated as a function of the speed error signal, generally
processed through a PI controller. The torque and flux command are processed in the calculation block. The
three phase reference current generated from the functional block is compared with the actual current in the
hysteresis band current controller and the controller takes the necessary action to produce PWM pulses. The
PWM pulses are used to trigger the voltage source inverter to drive the Induction motor. The Performance of the
indirect vector controlled drive has been analyzed for varying speed and torque. A PI controller is designed to
adjust the modulation index of the Hexagram inverter. From the simulation results it is found that the controller
tracks the reference speed is better at high speed range. In the low speed range the speed error increases
considerably and the PI controller needs further tuning to achieve better performance. This can be done using
Artificial intelligence techniques.
6. Comparison of Hexagram Inverter with CHB Inverter
A comparison of the Hexagram inverter and the CHB inverter is given in Table 1 due to their similarity in
modular structure and isolated dc buses. From Table 1, following conclusions are obtained:
• Cascaded H-bridge inverter requires more components than Hexagram inverter: six more transformer
secondary isolated windings; six more diode rectifiers, twelve more semiconductor switches, six more
capacitors. Although Hexagram inverter needs six inner inductors to block the circulating current, the
inductors are very small with all modules synchronize controlled.
• The capacitive energy storage requirement is low in the Hexagram inverter, since the instantaneous
power through each power module is constant, while the cascaded H-bridge inverter has low-frequency
pulsating power caused by the single-phase nature.
• With fewer components and lower component requirement, Hexagram inverter has less manufacturing
cost and higher reliability, which makes it a competitive topology for medium voltage variable speed
drive applications.
7. Simulation Results
The three phase induction motor drive with Hexagram inverter is simulated in Matlab/Simulink environment
with the parameters given in Appendix. The switching frequency for SPWM pulses is 1KHz, and the inner
inductors are 50µH each. Figure 7 shows simulation results at rated condition for a modulation index of 0.8.
Figure 7 (a) shows the 18 pulse transformer output with a phase shift of 0º, ± 20º at the three secondaries. The
other three secondaries will have the same phase shifts to achieve harmonic current cancellation in the utility
line currents, leading to clean input power. Figure 7 (b) shows the rectifier output and the voltage and current of
Hexagram inverter respectively. The steady state results showing the output voltage of the inverter and speed of
the induction motor for different modulation indices is shown in Table 2. A closed loop response of Hexagram
inverter with indirect field oriented control is analyzed for different operating conditions and the results are
presented in Figure 8. The speed reference is set at different values and the actual speed, torque, voltage and
stator current are observed and presented in Figure 8. The load torque is set at different values and the speed,
torque, voltage and stator current variations are shown in Figure 9. It is seen that the indirect field oriented
controller tracks the reference speed is less than 1 sec without exceeding the design limits. The performance of
the drive under low speed/less load operating conditions are studied through simulation and presented in Figure
10. The closed loop control of Hexagram drive has better performance in the low range of speed and torque
conditions.
8. Fault tolerant feature of the Hexagram inverter
The a2 to a3 leg of the inverter is opened and the output voltages and the current waveforms of the Hexagram
inverter are observed. It is seen from Figure (11) that the inverter output is reduced to 290.69V and 12.65 amps
respectively at rated condition when the inner leg a2 to a3 opened. Therefore, the overall inverter is capable of
operating at a reduced power level.
9. Conclusion
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The performance investigation of Hexagram inverter for a three phase induction motor drive is carried out for
medium voltage high power applications. The simulation model of the Hexagram inverter is developed in
Matlab/Simulink environment. The performance of the Hexagram inverter is analyzed into SPWM technique.
The Hexagram inverter has reduced component count and requirement, built-in fault tolerance, and full
utilization of the three-phase structure, which makes it a superior topology for high power applications. A closed
loop indirect field oriented controller is designed and its performance is studied for different speed and torque
conditions. It is seen that the controller tracks the reference speed is better at high speed range. In the low speed
range the speed error increases considerably and the PI controller needs further tuning to achieve better
performance. This can be done using artificial intelligence techniques.
APPENDIX
Parameters of the three phase induction motor
PARAMETERS VALUES
Power 7.5KW(10hp)
Voltage 400V
Frequency 50 Hz
No. of poles 4
Stator resistance (Rs) 0.7384 ohm
Rotor resistance (Rr) 0.7402 ohm
Stator inductance (Ls) 0.003045 H
Rotor inductance (Lr) 0.003045 H
Mutual inductance 0.1241 H
(Lm)
Inertia (J) 0.0343 kg.m^2
Friction (F) 0.000503 N.m.s
References
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Kim.I. D, Nho.E.C, Kim.H. G & Ko.J.S. (2004), “A generalized undeland snubber for flying capacitor
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Figure 1. Hexagram inverter.
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Figure 2. Hexagram inverter for a three phase induction motor drive.
Figure 3. Voltage phasor diagram of the Hexagram inverter. (a) Phase Voltages of VSI modules. (b) Output
Voltages of the Hexagram inverter.
Figure 4.
Current phasor diagram. Figure 5. Equivalent
circuit of the circulating current.
Figure 6. Closed loop control of hexagram inverter drive.
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Figure 7. Simulation results of Hexagram inverter.
Figure 8. Dynamic response of Hexagram inverter drive for varying speed.
Figure 9. Dynamic response of Hexagram inverter drive for varying torque.
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Figure 10. Dynamic response of Hexagram inverter
drive for low speed /less torque.
Figure 11. Fault tolerant feature of the Hexagram Inverter.
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Table 1. Comparison of Hexagram inverter with cascaded H-bridge inverter.
Comparison condition Multilevel Inverter Hexagram Inverter
No. of secondary windings 12 6
No. of Diode bridge rectifiers 12 6
No. of Power switches 48 36
Tabl
No. of Inductors 0 6 e 2.
No. of capacitors 12 6 Volt
age
variation of the Hexagram inverter for different Modulation indices.
Different load conditions MI-0.6 MI-0.8 MI-1
VL Nr VL Nr VL Nr
No load 365.7 1498 419 1499 640 1376
25% load 358.3 1454 413.1 1471 443.9 1523
50% load 357.5 1399 412.5 1447 517.8 1442
75% load 357.5 1330 412 1418 551.1 1360
100% load 357.1 1229 412.6 1383 443.9 1523
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