Current Sharing Analysis of Interleaved LCLC Resonant Converter

Current sharing in multiphase resonant converters is a serious concern as any small tolerance in the resonant tank components of different phases can lead to a large imbalance in the voltage gain and hence the load current imbalance. An interleaved LCLC resonant converter with four resonant components for wide input voltage range applications is studied in this paper. Because of the sharp voltage gain curve of the LCLC resonant converter, traditional current balancing approaches are not so successful. In this topology, the resonant tank impedances of each phase are tuned by a Switch-Controlled Capacitor (SCC) that is implemented in the resonant tank in both phases resulting in precise load current balancing among paralleled phases. The effect of different imbalance conditions on the interleaved LCLC resonant converter is studied, a minimum operating angle for the SCC circuit is identified and a control strategy is proposed for a reliable current sharing. The performance of the interleaved LCLC converter is validated by both computer simulation and experimental results of a two-phase 1kW prototype with 250V-400V input voltage. Further, a flat high-efficiency profile is achieved with different input voltage conditions over a wide load range.