Simulation Analysis of Hybrid Alternative Phase Apposition Disposition PWM Scheme for Cascaded Multilevel Inverters

In this paper, we present the performance of a hybrid alternative phase opposition disposition pulse width modulation technique for soft switched cascaded five level inverters. The proposed modulation scheme inherits the switching loss reduction along with reduced harmonic performance of cascaded multilevel inverter fed drive system. The inverter topology used here has recently suggested in the area of high power medium voltage applications. The performance of this cascaded inverter has been analysed and compared with the results obtained from theory and simulation. Simulation study of the inverter employing the proposed HAPOD strategy has been done in MATLAB/SIMULINK. Multilevel inverter has emerged recently in the area of high power medium voltage applications due to their advantages such as output waveform improvement which reduces the harmonic content in turn it reduces the size and cost of the filter and the level of electromagnetic interference (EMI) generated by switching operation. Multilevel inverters are of three types mainly; Diode clamped multilevel inverter, Flying capacitor multilevel inverter and Cascaded multilevel inverter. Among these three topologies cascaded multilevel inverters are most preferable since it overcomes the disadvantages of the other inverters. The main features of CMLI are 1. The level of extension is easy. 2. No voltage unbalancing problem. 3. It has modular structure. New modulations are newly developed to generate a stepped switched waveform with high power quality and minimum switching frequency. In this paper we proposed a new hybrid alternative phase opposition disposition modulation scheme to produce an efficient output voltage.