A Novel Phase-Shift Full-Bridge Converter With Separated Resonant Networks For Electrical Vehicle Fast Chargers

Abstract

As for traditional isolated hybrid switching step-down Phase-Shifted Full-Bridge converter, the switching frequency for Si-diodes in the assistant resonant network is as twice as that for other switches, which leads to longer reverse recovery time and lower current capacity. Hence, it is not suitable for high-power Electrical Vehicle fast charging application. In order to overcome the above drawbacks, the double-inductor rectifier with separated resonant networks is introduced into the Phase-Shifted Full-Bridge, where the high-frequency transformer combining double primary windings with common secondary winding is adopted for the input-series output-parallel system connection. The proposed topology has achieved a wide range of the leading leg zero-voltage switching and lagging leg zero-current switching. The capacitors in each resonant network helps to reset the primary currents during the circulating period leading to more efficiency. Especially the switching losses and conduction losses of the diodes in each resonant network is lower, which has good performance in high-power conversion. According to the experimental result, the maximum efficiency is 98.5%. The operating principle, theoretical analysis, design considerations are verified on a 20 kW, 20 kHZ experimental prototype.