A hybrid modulation method for single-phase quasi-Z source inverter

Single-phase quasi-Z source inverter (qZSI) needs large capacitance, and its switching loss is high when controlled by traditional SPWM. In this paper, a new modulation method for single-phase qZSI is proposed, which combines SPWM and pulse-width-amplitude modulation (PWAM), as a result of hybrid modulation. SPWM is employed at low dc-link voltage to avoid shoot-through state and act switching at low voltage stress; PWAM is used at high dc-link voltage to reduce switching actions. With the proposed hybrid modulation, switching actions and loss are reduced, also the required capacitance is significantly reduced. The simulation and experimental results verify the proposed hybrid modulation method. The lower size and higher efficiency are confirmed in the hybrid modulation controlled single-phase qZSI when compared to that with traditional SPWM.