A high efficiency voltage-fed quasi Z-source inverter with discontinuous input current using super-junction MOSFETs

This paper presents a high-efficiency quasi Z-source inverter with discontinuous input current deploying super-junction MOSFETs as bridge devices to minimise losses. Z-source inverters and quasi Z-source inverters can accommodate two major challenges exhibited by super-junction MOSFETs which would normally make their use problematic in traditional voltage source converters. Firstly, the intrinsic diodes of super-junction MOSFETs tend to exhibit adverse behaviour and secondly, the output capacitance, Coss, is highly non-linear with applied voltage increasing with reducing drain-source voltage. The losses exhibited by the bridge devices in the demonstrator converter at 1.525kW are 13W, or 0.78% and these devices do not require forced cooling, in contrast to IGBTs and p-n anti-parallel diodes when used as equivalent bridge devices.