Design and development of isolated snubber based bidirectional DC–DC converter for electric vehicle applications

Particularly, in the classical dual-active-bridge (DAB) converter, the current difference between the source and leakage inductance of high-frequency transformer potentially results in circulating current. This circulating current further causes the increased voltage stress, voltage overshoots, and conduction losses in the circuit. In view of this, a combination of dual-switch-forward (DSF) snubber and pre-charging method assisted isolated bi-directional DC-DC (BDC) converter is described in this study for electric vehicle application. The proposed configuration effectively diminishes the adverse impact of circulating current while reducing conduction loss, as well as switching stress. The working principle and corresponding circuit configurations are extensively discussed during both modes of operation. The control-to-output transfer functions have been obtained, and it has been confirmed that the system is stable for both modes of operation. The experimental prototype of 480 W for 20 kHz application has been developed using DSP TMS320F28335 to verify the practicality of the proposed converter. The experimental results assure that the voltage spike is successfully alleviated when the converter is operated with the proposed configuration. Finally, the comparative loss analysis has been carried out, which determines that the DSF snubber circuit with pre-charging method provides a better solution compared to classical converters/techniques.