High-Frequency-Link-Based Reactive-Power Optimal Control for Modular Multi-Active Bridge Converter

Modular multi-active bridge (MMAB) converter with inherent advantages of galvanic isolation, modularity and power density, can provide multiple dc ports for multifarious power conversion through high-frequency links (HFLs). However, the traditional single phase-shift control, which is widely applied in the converter due to the complex coupling among ports, leads to unfavorable efficiency performance. To independently handle each port with optimal capabilities, a dual-loop optimal control is proposed for MMAB converters to achieve the decoupling of active and reactive powers. Conditioning circuits are designed to extract power-related information that can be used to eliminate the fundamental reactive power, thus optimizing conducting and switching characteristics. The proposed control method regards each port as a subsystem regardless of the coupling through the HFL, which can be easily extended to multiport systems, which have HFL. Finally, the effectiveness of the proposed reactive-power optimal control strategy is validated on a hardware-in-the-loop-based four-port MMAB converter.