A new high frequency transformer assisted ZVS quasi-resonant DC-link PWM inverter with minimum voltage stress on the switches

This paper presents a new quasi-resonant DC-link (QRDCL) PWM inverter with zero voltage switching (ZVS) capability and easier control. The proposed quasi-resonant circuit creates zero voltage intervals in the DC-link to facilitate ZVS of the inverter switches under all operating conditions. This is achieved with the DC-link voltage being clamped at the source voltage V, using minimum additional components. It requires only two additional switches and a high frequency transformer compared to the conventional PWM converter. It has the ability of controlling the zero voltage interval of the DC-link without the intervention of the inverter switches. Moreover, the control circuit does not require any current/voltage sensing devices, thereby, making the control circuit simple and low cost. The operating principle of the circuit is explained and detailed analysis of each operating mode is given. A design criterion for achieving ZVS is obtained from the mathematical analysis. The feasibility of the proposed circuit operation has been verified by PSPICE simulation. The simulation results show full ZVS for both the proposed circuit and the PWM inverter