Multi-level inverter for induction motor drives: Implementation using reversing voltage topology

Multi-level inverter technology has emerged recently as a very important alternative in the area of medium-voltage high-power energy control. Due to higher number of dc voltage sources, lower EMI, requirement of semiconductor power devices with less blocking voltage, lower % THD in output voltage and less stress on insulation, they are widely used. However, it has some disadvantages as complicated PWM controlling method, increased number of components, complex power bus structure in some topologies, and voltage balancing problem at neutral point. In this paper, a new topology called Reversing Voltage is implemented (which was previously proposed) to improve multi-level performance by compensating the disadvantages just mentioned. This new power converter topology requires fewer components compared to available multi-level inverters (especially in higher-levels) and requires less carrier signals for PWM implementation. Proposed induction motor drive structure offers reduced device count, simple power-bus structure when compared to a conventional five-level NPC and flying capacitor inverter fed induction motor drives. The topology and the control method based on SPWM are shown and the requirement of components is also compared to other topologies to show the superiority of the presented topology. Finally simulation and experimental results on different types of loads are presented and discussed.