Three-Phase LLCL Bidirectional Resonant Converter With Wide Output Voltage Range

This article proposes a three-phase LLCL bidirectional resonant dc-dc converter with wide voltage range in both ports. Combined with the interleaving technique, the converter can effectively reduce the current ripples of input and output ports, and the size of filter capacitors can be extremely reduced. Meanwhile, with three power transmission paths and the ability of self-current sharing, the converter has a larger power capacity and higher power density compared with conventional LLC converters. The operation principles and the detailed design method are presented in this article. Finally, a 3.3-kW prototype, which interfaces the dc bus and battery, is built to validate the effectiveness and applicability of the proposed converter. During the whole time, the bus voltage is fixed at 400 V. In forward mode, the output voltage range is 250-420 V, and the peak efficiency of up to 97.8%. In backward mode, the inverter side voltage range is 300-420 V, and the peak efficiency of up to 98.0%.