A Comparative Study of PWM Strategies for Cascaded Z-Source Multilevel Inverter

Abstract - Multilevel Inverter (MLI) is an effective topology for high voltage DC-AC conversion. It synthesizes a desired voltage wave shape from several levels of DC voltages. But the main disadvantage of MLI is its output voltage amplitude is limited to DC sources voltage summation. Therefore, a five-level symmetric cascaded multilevel inverter based Zsource inverter has been proposed in this paper. In the proposed topology output voltage amplitude can be boosted with Z network shoot-through state control. This paper focuses on Unipolar, bipolar and Third harmonic injection PWM strategies for the proposed topology. The performance of Z -Source MLI has been analyzed for various modulation strategies. A simulation model of conventional cascaded multilevel inverter and Z-source MLI has been built in MATLAB/SIMULINK.