Comparison of Different Types of SPWM Techniques for Three Phase Seven Level Cascaded H-Bridge Inverter

Recently multilevel inverters are emerged as very important factor in high power and medium voltage application. Number of inverter topologies have been introduced and used for various application. Among these inverters cascaded MLI is used because of its advantages over other MLIs. Different control techniques are available to control these inverters. This paper presents a comparison of different sinusoidal pulse width modulation(SPWM) techniques for three phase seven level cascaded H-Bridge inverter such as IPD, APOD, POD, phase shifted(PS) and hybrid(Combination of phase shifted and level shifted) SPWM techniques. These techniques are proposed in order to ensure an efficient voltage utilization and better harmonic spectrum. In this paper special attention is given to the THD of output voltage of the multilevel inverter using different SPWM techniques. Simulation outputs of three phase seven level cascaded H-Bridge using different control techniques are analysed in PSIM environment.