Design of 1 kW bidirectional half-bridge CLLC converter for electric vehicle charging systems

Abstract

DC-DC converters are utilized in many applications such as automobiles, chargers, uninterrupted power supplies (UPS), and renewable energy systems. Galvanically isolated DC-DC converters are usually selected in electric vehicle (EV) battery charging systems. The converters typically interface between a DC link and a high voltage battery pack. Resonant CLLC DC-DC converters can achieve galvanic isolation, bidirectional power flow, and high efficiency, which make them good candidates for bidirectional EV charging systems. In this paper, a bidirectional half-bridge CLLC converter is designed and evaluated. An optimal soft-switching feature is applied in the design. The operating principle, design methodology and some considerations are presented. The prototype with 1 kW power rating interfaces a 300 - 600 V DC link and a high voltage battery pack (200 - 400 V). The performance in terms of efficiency, control complexity, component stress and cost is analyzed.