An Improved Zero-Voltage-Switching Inverter Using Two Coupled Magnetics In One Resonant Pole

A novel soft switching inverter using two small coupled magnetics in one resonant pole is proposed to guarantee the main switches operating at zero-voltage-switching (ZVS) from zero load to full load and the auxiliary switches at zero-current-switching (ZCS) with load adaptability and small current stress. Since independent magnetics structure avoids the unwanted magnetizing current freewheeling loop, the size of the coupled magnetics can be minimized with low magnetizing inductance and the saturable inductor is eliminated. Detailed circuit operation is described and voltage-second balance condition of the magnetics is expressed mathematically. A 4-kW hardware prototype has been designed, fabricated and tested to verify the validity of the novel circuit and the improved performs of the proposed soft switching inverter. Experimental results show excellent agreement with analytical results.