Enchance Design of Single Phase H-Bridge Multilevel Inverter

Abstract

The power electronics device which converts DC power to AC power at required output voltage and frequency level is known as inverter. The voltage source inverters produce an output voltage or a current with levels either 0 or +ve or -ve V dc. They are known as two-level inverters. Multilevel inverter is to synthesize a near sinusoidal voltage from several levels of dc voltages. Multilevel inverter has advantage like minimum harmonic distortion. Multi-level inverters are emerging as the new breed of power converter options for high power applications. They typically synthesize the stair –case voltage waveform (from several dc sources) which has reduced harmonic content. In this project work hardware model of Three-level single phase cascade H-Bridge inverter has been developed using MOSFETS. Gating signals for these MOSFETS have been generated by designing comparators. In order to maintain the different voltage levels at appropriate intervals, the conduction time intervals of MOSFETS have been maintained by controlling the pulse width of gating pulses by varying the reference signals magnitude of the comparator. The results of hardware are compared with simulation results. Simulation models designed in SIMULINK have been developed up to five levels and THD in all the cases have been identified.