Zero-voltage and zero-current-switching full bridge PWM converter for high power applications

A novel zero-voltage and zero-current-switching (ZVZCS) full bridge (FB) PWM converter is proposed. The new converter overcomes the limitations of the ZVS-FB-PWM converter such as high circulating energy, severe parasitic ringing on the rectifier diodes, and limited ZVS load range for lagging leg switches. By utilizing the DC blocking capacitor and adding a saturable inductor, the primary current during the freewheeling period is reduced to zero, allowing the lagging leg switches to be operated with ZCS. Meanwhile, the leading leg switches are still operated with ZVS. The new converter is attractive for high voltage, high power applications where IGBTs are predominantly used as the power switches. The principle of operation, and DC characteristics of the new converter are analyzed and verified on a 2 kW, 83 KHz experimental circuit.<>