Transformer Current Spike Elimination for Dual Active Bridge Converter Considering Multiple-Phase-Shift Modulation

With the development of the modulation strategies for dual-active-bridge (DAB) converters, single-phase-shift (SPS), dual-phase-shift (DPS) and triple-phase-shift (TPS) have been proposed aiming at the realization of zero-voltage-switching (ZVS) or elimination of the reactive power at different power and voltage. While the previous work mainly focuses on the steady-state operation or the small-signal model for one specific modulation strategy, the real practice requires modulation strategies to switch among SPS, DPS and TPS frequently during the load transients, which can cause a current spike and dc-bias current in the transformer. Therefore, a smooth transition among different modulations is necessary. This paper proposes a duty-cycle compensation method to eliminate such current spike and DC bias. The implementation of the proposed method in the control loop is also discussed. Finally, the experimental results are provided to validate the performance of the duty-cycle compensation method.