Research on Power Decoupling and Optimal Control of Modular Multiactive Bridge Converter With Relay Port

Modular multiactive bridge (MMAB) converter is a modular, scalable, and promising multiport converter that facilitates flexible interconnection among various power sources and loads. In the conventional MMAB configuration, all ports are coupled to a common high-frequency link through multiple high-frequency transformers, which inherently induces cross-coupling power flow between ports. This article proposed a modified MMAB converter structure incorporating an additional relay port to achieve hardware-level power decoupling. The proposed topology does not require a complex control strategy and allows each port to operate independently as an individual dual-active bridge converter without interaction. The principle of power flow decoupling is analyzed in detail using frequency-domain analysis. Furthermore, an optimal design and control method based on duty ratio control is proposed to expand the zero-voltage switching operating range of the converter. The proposed structure also effectively suppresses the high-frequency oscillation within the MMAB converter. Finally, simulation and experimental results were obtained from different test scenarios to verify the power decoupling performance and the proposed control strategy.