Soft Switching Voltage Source Inverter with Parallel Resonant DC Link

This paper proposes a novel soft-switching voltage source inverter with parallel resonant DC link to improve efficiency of inverter.We added auxiliary resonant unit to DC link of conventional inverter to make DC-bus voltage decreased to zero periodically,which realized zero-voltage operation of all switching devices in inverter.Furthermore,we also operated auxiliary switches under zero voltage switching or zero current switching.In addition,we avoided the bulk capacitor in the circuit and there was no center tap potential variation problem.We analyzed the operation principle and presented the equivalent circuits at different operation modes.We had built a 5kW laboratory prototype.Experimental results show that we can operate main switching devices under zero voltage and enhance the efficiency by 3% under rating power,compared with hard-switching inverter.