scholarly journals Analysis and Implementation of Unipolar PWM Strategies for Three Phase Cascade Multilevel Inverter Fed Induction Motor Drive

Author(s):  
Ravikumar Bhukya ◽  
P. Satish Kumar

This paper presents unipolar pulse width modulation technique with sinusoidal sampling pulse width modulation are analyzed for three-phase five-level, seven-level, nine-level and eleven-level cascaded multi-level inverter. The unipolar PWM method offers a good opportunity for the realization of the Three-phase inverter control, it is better to use the unipolar PWM method with single carrier wave compared to two reference waves. In such case the motor harmonic losses will be considerably lower.The necessary calculations for generation of unipolar pulse width modulation strategies have presented in detail. The unipolar SPWM voltage switching scheme is selected in this paper because this method offers the advantages of effectively doubling the switching frequency of the inverter voltage. The cascaded multi level inverter fed induction motor is simulated and compared the total harmonic distroction for all level (five-level, seven-level, nine-level and elevel-level)of the inverter. Theoretical investigations were confirmed by the digital simulations using MATLAB/SIMULINK software.

Author(s):  
Ravikumar Bhukya ◽  
P. Satish Kumar

<p>This paper presents new modified space vector pulse width modulation techniques (Phase disposition-Space vector pulse width modulation, Alternative Phase Opposition disposition- Space vector pulse width modulation and Phase Opposition disposition-Space vector pulse width modulation) are analyzed for three-phase cascaded multi-level inverter fed induction motor from the point of view of the Phase voltages, line voltage, stator current,speed,torque and Total harmonic distortion.in the proposed modified technique the reference signals are generated by adding offset voltage to the reference phase voltages.This modified SVPWM technique does not involve region indentification,sector identification for switching vector determination as are required in the conventional multi level SVPWM technique,it is also reduces the computation time compared to the conventional space vector PWM technique.The necessary calculations for generation of new modified SVPWM for the modulation strategies have presented in detail.  It is observed that the modified SVPWM modulation ensures excellent, close to optimized pulse distribution results and THD is compared to for five-level, seven-level, nine-level and eleven-level Cascaded H-Bride Multi-level Inverter fed to Induction motor. Theoretical investigations were confirmed by the digital simulations using MATLAB/SIMULINK software.</p>


Author(s):  
Periyaazhagar D ◽  
Irusapparajan G

In this paer, the suggested topologies are gained by cascading a full bridge inverter with dissimilar DC sources. This topology has a several new patterns adopting the fixed switching frequency, multicarrier control freedom degree with mixture conceptions are established and simulated for the preferred three-phase cascaded multilevel inverter. In outstanding switching arrangement terminations, there are convinced degrees of freedom to produce the nine level AC output voltages with terminated switching positions for producing altered output voltages. These investigations focus on asymmetrical cascaded multilevel inverter engaging with carrier overlapping pulse width modulation (PWM) topologies. These topologies offer less amount of harmonics present in the output voltage and superior root mean square (RMS) values of the output voltages associated with the traditional sinusoidal pulse width modulation. This research studies carries with it MATLAB/SIMULINK based simulation and experimental results obtained using appropriated prototype to prove the validity of the proposed concept.


Author(s):  
M Nalini Devi ◽  
◽  
R Srinu Naik ◽  

A generalized procedure of decoupled pulse width modulation (DCPWM) based on Method called Direct Torque Control (DTC) for Open Ended Winding Induction motor drive (OEWIM) is anticipated in this paper. This drive topology uses two isolated dc sources with equal magnitudes, feeding two standard two level three-phase inverters. To overcome the complexity in classical space vector pulse width modulation (SVPWM) algorithm, a simple generalized approach is presented in this research by using the phase voltages. With this procedure, various PWM algorithms can be generated by varying a constant value. The dual inverters are operating independently with half of the switching frequency. To show the usefulness of proposed PWM fed DTC drive, simulation results analysis has been carried out by using MATLAB and results obtained.


This paper deals with sensorless vector controlled induction motor in which torque pulsations are reduced with improved input of induction motor. In proposed technique two multi winding transformers are used for generation of 18 sinusoidal signals given to rectifier unit and the rectifier output given as input to 9 level multi level inverter. In this proposed technique gating signals to the inverter switches will be provided through space vector pulse width modulation which considers speed as reference. This configuration was simulated in MATLAB/Simulink.and the simulation results are presented here with improvement in reduction of THD.


Author(s):  
Amirah J. Mohammed ◽  
◽  
Raaed F. Hassan

The work presented in this paper aims to compare the effectiveness of different control strategies to improve the performance of the three-phase Induction Motor (IM). The Conventional Direct Torque Control (CDTC) was employed as the first strategy for driving the IM. This control strategy causes high ripples in the IM's torque and speed due to the hysteresis comparators and a variable switching frequency due to the look-up table. A modified DTC strategy based on Space Vector Modulation (DTC-SVM) was chosen as a second strategy to enhance the performance of the IM using the two-level inverter. This method, which leads to the reduction of the torque and speed ripples and achieves constant switching frequency. As the multi-level inverter becomes most popular than the two-level inverter, the third strategy is devoted to adopting the three-level flying capacitor inverter (TLFCMLI) -based DTC-SVM. The third strategy uses the method of mapping the multi-level space vector based on basic two-level SVM. Matlab/Simulink software package is utilized to implement the suggested controllers. Simulation results show that the DTC-SVM based on TLFCMLI significantly enhances the IM's performance compared with the other two strategies from the voltage and current profiles, torque, and speed points of view.


Author(s):  
Jyothi B ◽  
M.Venugopala Rao

<p>Multiphase (more than three phases) is very much popular due to their eminent features compared to conventional three-phase counter parts. In order to drive the multiphase machine, it requires same phase input w.r.t the no of phases at the output. This paper mainly focuses on five phase, because even after failure of one phase, the performance does not degraded much. Voltage source inverters (VSIs) are used to feed the induction motor. voltage source inverters (VSIs) switches are ON and OFF precisely to control the output. In order to implement harmonic waveform characteristic, carrier based PWM (pulse width modulation) is performed. By using with and without third harmonic injection machine torque is highly improved. Using MATLAB software, the simulation results are presented in the form of computer traces and high traded performance of the machine are discussed.</p>


Author(s):  
Nunsavath Susheela ◽  
Satish Kumar

<p>Multilevel inverters (MLI) are becoming more popular over the years for medium and high power applications because of its significant merits over two level inverters. This paper presents an implementation of multicarrier based sinusoidal pulse width modulation technique for three phase seven level diode clamped multilevel inverter.  This topology is operated under phase opposition disposition pulse width modulation technique. The performance of three phase seven level diode clamped inverter is analyzed for induction motor (IM) load.  Simulation is performed using MATLAB/SIMULINK. Experimental results are presented to validate the effectiveness of the operation of the diode clamped multilevel inverter using field programmable gate array.</p>


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