H-bridge based Multilevel Inverter using PWM Switching Function

This paper proposes an efficient PWM switching function for modified H-bridge based multilevel inverter. The prior H-bridge based multilevel inverter can increase the number of output voltage levels by adding switch components and dc input voltage sources. If it employs seven switches and three dc sources, the number of output voltage levels becomes seven. Although its THD characteristics are improved, it needs output filter to meet general output voltage THD requirement, i.e., 5% below. To mitigate this problem, we propose an efficient PWM switching method for the prior H-bridge based multilevel inverter. By adding PWM switching schemes to the operation of the prior H-bridge switches, it can synthesize more sinusoidal waveform. By this simple alteration in the switching scheme, it can improve the output voltage THD requirement. To verify the high performance of the proposed switching scheme, we implemented computer-aided simulations and experiment using a prototype.