An isolated bi-directional soft switching DC-DC converter for energy storage system and its voltage stress suppression approach

In recent years, kinetic energy storage systems with electric double layered capacitor (EDLC) bank have been widely studied and developed for the fuel cell electric vehicles(FCEV). In this paper, a full-bridge/push-pull inverter based isolated bi-directional DC-DC soft switching converter for EDLC interface is proposed. The DC-DC converter mentioned here has the great advantage that the number of the switching power devices can be reduced compared to the conventional full-bridge/full-bridge inverter based DC-DC converter. The lower conduction losses can be achieved by this advantage as well as cost reduction. Though, a non-negligible drawback of the full-bridge/push-pull inverter based DC-DC converter has been revealed that is high voltage stress caused by the voltage ringing through the lossless snubber capacitor and leakage inductance of the high frequency transformer. To eliminate this drawback, a low leakage transformer is implemented to the DC-DC converter. The computer aided simulation and the experimental results demonstrate that the adequacy of the proposed circuit and its voltage suppression technique.