Universal Phase-Shift Modulation Scheme and Efficiency Optimization for Modular Multiactive Bridge Converter

Phase-shift modulation has been widely adopted in dual active bridge (DAB) converters due to its simple implementation and great system performance. However, modular multiactive bridge (MMAB) converter, a multiport version of DAB, has poor efficiency performance under traditional single phase-shift control and lacks a comprehensive analysis of multiphase-shift modulation. In order to improve the efficiency under unfavorable working conditions, this article proposes a universal phase-shift (UPS) modulation scheme for MMAB as well as multiactive bridge converters where the port numbers can be flexibly scaled. A time-domain mathematical model under the UPS scheme is obtained by a decomposition-and-superposition modeling method. Based on the model, an optimization strategy, aiming at full zero-voltage-switching turn-
on
actions and minimized root-mean-square inductance currents, is proposed to reduce the overall power loss. The proposed optimization strategy takes simplicity, scalability, and optimization performance into consideration, and its optimization effects can be regarded as a global optimum. Finally, a four-port laboratory prototype of MMAB converters has been constructed. The effectiveness and superiority of the proposed UPS control strategy within the full working range have been verified by experimental results.