A Novel Asymmetric Three-Phase Cascaded 21 Level Inverter Fed Induction Motor Using Multicarrier PWM with PI and Fuzzy Controller

A Abdul Namith,T S Sivakumaran

doi:10.4236/cs.2016.711327

Abstract

Multilevel inverters are gaining popularity in high power applications. This paper proposes a new ladder type structure of cascaded three-phase multilevel inverter with reduced number of power semiconductor devices which is used to drive the induction motor. The ultimate aim of the paper is to produce multiple output levels with minimum number of semiconductor devices. This paper uses only 11 switches along with 3 diodes and 4 asymmetrical sources to produce an output voltage of 21 levels. The modulation technique plays a major role in commutation of the switches. Here we implement the multicarrier level shifting pulse width modulation technique to produce the commutation signals for the inverter. The proposed multilevel inverter is used to drive the three-phase induction motor. The mathematical modeling of three-phase induction motor is done using Simulink. Furthermore the PI and fuzzy logic controllers are also used to produce the reference waveform of the level shifting technique which in turn produces the commutation signals of the proposed multilevel converter. The controllers are used to control the speed of the induction motor. The effectiveness of the proposed system is proved with the help of simulation. The simulation is performed in MATLAB/Simulink. From the simulation results, it shows that the proposed multilevel inverter works properly to generate the multilevel output waveform with minimum number of semiconductor devices. The PI and fuzzy logic controller performances are evaluated using the results which indicate that with the help of controllers the harmonics has been reduced and the speed control of induction motor is achieved under different loading conditions.

Highlights

In recent years the energy demand is moving on increasing toward generating power with renewable energy source that may be dispersed in a wide area, and most of them are renewable, as they have greater advantages due to their environmentally friendly nature
This paper proposes a new ladder type structure of cascaded three-phase multilevel inverter with reduced number of power semiconductor devices which is used to drive the induction motor
The simulation is performed in MATLAB/Simulink. It shows that the proposed multilevel inverter works properly to generate the multilevel output waveform with minimum number of semiconductor devices

Summary

Introduction

In recent years the energy demand is moving on increasing toward generating power with renewable energy source that may be dispersed in a wide area, and most of them are renewable, as they have greater advantages due to their environmentally friendly nature. In [1], RuizCaballero et al propose a symmetrical multilevel inverter with spwm technique This system uses only switches and DC sources. In [2], Xiaotian Zhang et al propose the study of the multi sampled multilevel inverters and their control techniques to improve the performance of the multilevel inverters This deals with the different control techniques to be implemented in multilevel inverters in order to reduce the THD. In [4], Ayoub Kavousi et al come with the new algorithm for producing the switching signals They propose BEE algorithm to produce the modulation signals; the algorithm works better than the other techniques but the structure of cascaded multilevel inverter remains same. In [5], Roshankumar et al use the five-level inverter to drive the induction motor They propose cascading of flying capacitors to produce five levels at the output. The circuit uses the capacitors; balancing of capacitor voltage becomes a great problem and the capacitor usage makes the circuit big and more complex and the cost of the entire system increases

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Results

Conclusion