A step-up/down single-stage ZVS inverter

In many applications such as power converters for fuel cells or distributed generating (DG) systems there is a need to increase the DC voltage before being inverted to AC grid or load with a higher voltage. The standard approach is to use a DC-DC converter to boost the input voltage followed by a buck inverter to converter the increased DC voltage into AC. Having two stages of conversion results in higher losses, volume, cost and component count. In this paper a single-stage inverter is proposed with desirable properties of step-up/down conversion as well as zero voltage switching (ZVS). Due to only one stage of conversion fewer components are used compared to the double-stage converters, and the cost and volume is lower. ZVS allows using higher switching frequency and smaller passive components and faster dynamic response. The predictions of circuit analysis and the suggested optimal control scheme are verified by simulation as well as by experimental results.