Quasi-resonant soft-switching inverter for low and high power factor loads

A novel quasi-resonant three-phase inverter is proposed for 400 or 50 Hz low and high power factor loads. The proposed quasi-resonant DC link consists of a total of four switches, two resonant inductors and a capacitor. Two switches are connected in series with the resonant DC link (RDCL) and the other two are connected across the RDCL. The quasi-resonant link topology is versatile and the operation is such that the DC link voltage is clamped to the source voltage. The soft-switching operation of the quasi-resonant inverter is explained in terms of modes for both positive and negative link current. The quasiresonant inverter is operated under modified space vector modulation incorporating soft switching. SABER simulation of the resonant link inverter and subsequent experimental verification show good agreement.