ZVZCS three-level DC-DC converter using passive clamping circuit

This paper proposes a zero-voltage and zero-current-switching three-level (ZVZCS TL) DC-DC converter using passive clamping circuit to reduce switching loss, improve current trails of IGBT and improve the converter efficiency. The proposed TL converter can achieve effective zero-voltage switching (ZVS) for the TL leg and zero-current switching (ZCS) for the two-level leg. By using the passive clamping circuit, the proposed converter can reduce voltage stress on switches, widen load range for soft-switching, reduce switching loss, and can reduce the secondary transient over voltage. The loss of the auxiliary clamping circuit is very low. The principle and operation modes of the converter are analyzed and the necessary condition of soft switching is also analyzed. The proposed theory has been verified on a 24V/6A, 60 kHz experimental prototype.