Design and Implementation of Bidirectional Full-Bridge Soft-Switching DC/DC Converter with Natural Clamping

The main purpose of this paper is to design and implement a bidirectional full-bridge phase-shift (BPSFB) converter with snubber-less natural clamping for application such as EVs. In the charging stage, the phase shift control is used to achieve zero-voltage-switching and two additional clamping diodes and a small resonating inductance are used for natural clamping. In the discharging stage, the current fed technique is used for transferring energy between the battery and dc bus. By applying the dc bus voltage to the leakage inductance of the transformer for an appropriate time duration, during the inductor energy storing period in battery side, the voltage spike on main power switches can be reduced without snubber circuits. Finally, the digital signal processor, TMS320F28035, is used as the controller to realize the laboratory prototype with bus voltage 400 V, battery voltage 350-400 V and rated power 4kW. During the charging stage, the maximum efficiency is 98.2% at 75% load and during discharge stage, the efficiency is 96.8% at 50% load.