An improved soft-switching PWM FB DC/DC converter for reducing conduction losses

An improved soft-switching topology of a full-bridge (FB) pulsewidth-modulated (PWM) DC/DC converter is described. The new topology employs an energy-recovery snubber to minimize a circulating current flowing through the transformer and switching devices. By using an energy-recovery snubber instead of adding a tapped inductor and a saturable reactor to reduce RMS current stress, the converter achieves zero-current switching (ZCS) for the right leg due to the minimized circulating current and achieves zero-voltage switching (ZVS) for the left leg due to the reflected output current during the interval of left leg transition. Both analysis and experiments are performed to verify the proposed topology by implementing a 7 kW (120 VDC, 58 A) 30 kHz insulated gate bipolar transistor (IGBT) based experimental circuit.