Dual Half-Bridge DC-DC Converter With Wide-Range ZVS and Zero Circulating Current

A new converter topology that is both high power and digitally controlled combines two half-bridge inverters to operate as a full-bridge power stage using phase-shifting control, but with zero circulating current. Each power switch operates with a nominal 50% duty cycle to achieve zero-voltage switching over a widely varying load, but can also function in pulsewidth modulation mode for increased output voltage regulation range. Light-load efficiency can be improved by turning OFF one half-bridge inverter. A 1-kW 385-48 V converter designed to validate the concept achieved both 96+% efficiency and high power density.