ZERO-VOLTAGE AND ZERO-CURRENT-SWITCHING FULL BRIDGE PWM CONVERTER FORHIGH-POWER APPLICATIONS

A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge (F B) pulse-width modulated (PWM) converter is proposed, The new converte r overcomes the limitations of the zero-voltage-switching (ZVS)-FB-PWM converter, such as high circulating energy, loss of duty cycle, and l imited ZVS load range For the lagging-leg switches, By using the dc bl ocking capacitor and adding a saturable inductor, the primary current during the freewheeling period is reduced to zero, allowing the laggin g-leg switches to be operated with zero-current-switching (ZCS). Meanw hile, the leading-leg switches are still operated with ZVS, The new co nverter is attractive for high-voltage (400-800 V), high-power (2-10 k W) applications where IGBT's are predominantly used as the power snitc hes, The principle of operation, features, and design considerations o f the new converter are described and verified on a 2-kW, 100-kHz. IGB T-based experimental circuit.