Full-bridge soft switching PWM converter with saturable inductors at the secondary side

An improved full-bridge (FB) soft switching DC-to-DC converter with saturable inductors at the secondary side is presented and analysed. The main devices are switched on under zero-voltage conditions using the energy stored in the secondary saturable inductors. On the other hand, the secondary diodes are switched off under zero-current conditions due to the large inductance of the saturable inductors when it is not saturated. The advantages of this converter include a wide load range with zero-voltage-switching (ZVS) and zero-current-switching (ZCS), a large effective duty ratio, and no secondary voltages spikes, in addition to high power density and high efficiency. Experimental results obtained on a 6kW prototype are discussed.