A new ZVS full-bridge DC-DC converter for battery charging with reduced losses over full-load range

A new zero voltage switching (ZVS) full-bridge DC-DC converter for traction battery charging is proposed in this paper. The proposed isolated DC-DC converter is a part of AC-DC converter in an electric vehicle charger. The main active switches in the converter turn-on at zero voltage over full-load range with the help of passive auxiliary circuit. The diode clamping circuit on the primary side eliminates the voltage spikes on the secondary rectifier diodes which are commonly present in conventional full-bridge DC-DC converters. The main switches are controlled with the proposed asymmetrical pulse width modulation (APWM) technique resulting in higher efficiency. APWM reduces the current stress of the main switches and the circulating losses by minimizing the auxiliary reactive current over the full-load range of DC-DC converter compared to conventional phase-shift modulation (PSM) method. The steady-state analysis of the converter is explained in detail with time intervals and respective governing analytical equations are provided. A 100kHz, 1.65kW full-bridge DC-DC converter is implemented on ORCAD/Pspice simulation platform and the ZVS results at full-load and light load, and secondary voltage result at full-load are presented. The advantage of APWM over PSM is also verified through the current stress results of the main switches at different loads for the proposed DC-DC converter.