IGBT based zero voltage transition full bridge PWM converter for high power applications

A novel zero-voltage-transition (ZVT) full-bridge (FB) PWM converter for high power applications is proposed. An auxiliary resonant network which consists of two small switches (10- 20% of main switches) and one small inductor provides zero-voltage-switching (ZVS) for wide line and load ranges. This allows addition of external capacitors to the switches maintaining reasonable ZVS range, and IGBTs can be used instead of MOSFETs for the main switches. In addition, the proposed converter has advantages over the ZVS-FB-PWM converters such as minimum device voltage and current stresses, negligible duty cycle loss, and no severe parasitic ringing on the secondary, which enables the proposed converter to handle higher voltage and power with lower cost. Operation, features and design considerations are presented and verified experimentally on a 2kW, 85kHz IGBT based prototype.