Reducing the high frequency transformer losses in an FB ZVT PWM converter

This paper proposes a full bridge zero voltage transition (FB ZVT) PWM DC-DC converter, which uses a saturable reactor, instead of two additional switches to achieve zero voltage switching. A conventional, high frequency, phase shifted, FB ZVT PWM DC-DC converter has a disadvantage, in that a circulating current flows through the high frequency transformer and switching devices during the free-wheeling interval. Due to this circulating current, the conduction loss increases. To reduce this loss, the proposed circuit reduces the circulating current. The operation principles are explained in detail and several interesting simulation and experimental results verify the validity of the proposed circuit