An improved full-load-range isolated ZVS-PWM DC-DC converter

This paper presents an improved DC-DC converter with half of the input voltage across main switches, operating with zero voltage switching (ZVS) at full-load-range. No extra active components are necessary to achieve ZVS. Soft commutation is possible due to the presence of auxiliary resonant inductors. Two series inductors assure ZVS at high current load, while two parallel inductors assure ZVS at light current load. In this way, ZVS can be obtained for full-load-range. These features are especially interesting for applications such as telecommunications and battery charging. Analysis of the converter operation, as well as design procedures to define the values of inductors that maximize the converter efficiency are presented. Experimental results of a 1.5 kW prototype converter operating at 100 kHz with isolated 60 V/25 A output are presented. The measured efficiency was 92% at full load.