A new duty-cycle-shifted PWM control scheme for half-bridge DC-DC converters to achieve zero-voltage-switching

Asymmetric control scheme is an approach to achieve ZVS for half-bridge isolated DC-DC converter. However, it is not suited for wide-range input voltage due to the uneven voltage and current components stresses. This paper presents a new "duty-cycle-shifted PWM control" scheme for half-bridge isolated DC-DC converters to achieve ZVS operation without asymmetric penalties and without adding additional components. Because the duty cycle width is kept identical for both switches, the asymmetric current and voltage stresses problem is eliminated. The principles of operation and key features are illustrated. Experimental results verify that higher efficiency is achieved with the proposed "duty-cycle-shifted" control method, especially at higher switching frequency.