A ZVS-PWM T-Type Isolated DC-DC Converter

This paper presents the T-Type Zero Voltage Switching Pulse Width Modulated isolated DC-DC converter (TT-ZVS-PWM Converter). The proposed topology is composed of four switches. Two of these are subjected to the input voltage and the other two to half the input voltage. All switches commutate under zero-voltage. The proposed converter has the following in common with the Full Bridge Zero-Voltage Switching (FB-ZVS-PWM) and the Three-Level Zero-Voltage Switching (TL-ZVS-PWM) converters: (a) symmetrical operation of the isolation transformer, (b) modulation by pulse-width with constant frequency, (c) zero voltage switching, and (d) three-level voltage applied to the primary winding of the transformer. Theoretical analysis, design example and experimental data for a 3 kW, 400 VDC input, 60 VDC output, and 50 kHz switching frequency laboratory prototype, are included in the paper. Measured efficiency was 93% at full load and 95.2% at 1.2 kW.