Current-tripler-rectifier pulse width modulation ZVS three-phase full-bridge DC/DC converter with Y–Δ connected transformer

To decrease the current stress of the switches in high power applications, a current-tripler-rectifier zero voltage switching (ZVS) three-phase full-bridge DC/DC converter with pulse width modulation (PWM) control strategy is proposed in this study. The converter utilises a three-phase full-bridge structure at the primary side and a current-tripler rectifier at the secondary side. The converter applies to situations involving high power, high input voltage and large output current. The three-phase interleaved structure not only decreases the current stress of the switches, but also increases the frequency of input and output current ripple to three times as large as the switching frequency, which reduces the filter inductance. All switches achieve ZVS with the proper PWM control strategy. It is quite easy to achieve ZVS for lower switches of the bridge leg since the energy coming from the output filter inductor discharges the junction capacitors. Since the energy of upper switches achieving ZVS comes from the leakage inductors of two phase transformers, it is easier to achieve ZVS for upper switches of this converter than lagging-leg switches of the phase-shifted full-bridge converter. A prototype with 360 V input and 48/42 A output was built in the lab and experimental results verified the theoretical analysis.