Topology optimisation and current sharing strategy of interleaved bidirectional dc/dc converter with coupling technique

The dc/dc converter with interleaving and coupling technique is preferred in high-power applications for its excellent steady-state and transient-state performances. In this study, the principle of three-phase interleaved dc/dc converters with a coupled inductor is first analysed. Also, merits are proved theoretically based on the concepts of equivalent steady-state and transient-state inductance. As most of the proposed single-core coupled inductor may suffer several issues, such as asymmetrical coupling parameters, high manufacturing cost, and large dc flux, an equivalent model is then deduced to use two-wingding coupled inductors instead of the single-core three-phase coupled inductor. With the proposed model, the manufacturing cost can be reduced, the parameters can be symmetrical and there will be nearly no dc flux. In real applications, however, the proposed model may also be faced with current unbalance among phases, which may lead to core saturation and even system failure. A phase-decoupled current sharing strategy is therefore proposed and used in the proposed topology. The superiority and practicability of proposed topology and current sharing method are verified by simulation in PSIM and prototype experiment results.