High-Efficiency Time-Division Multiplexing Modulation Technology for Modular Multiactive Bridge Converters

In this article, a time-division multiplexing (TDM) modulation technology is proposed to enhance the efficiency of modular multiactive bridge (MMAB) converters in multiport power electronic transformers over a wide operating range. The TDM modulation retains the simplicity of single phase-shift (SPS) modulation while achieving efficiency improvement by adopting different structures (i.e., half-bridge and full-bridge) under different operating conditions with dc bias capacitors. However, determining the optimal structure under the same operating condition poses a significant challenge due to the strong coupling among MMAB ports. To address this issue, this article analyzes a dual-active bridge converter to investigate the steady-state characteristics of different structures, including the root-mean-square current and zero-voltage switching. By decomposing the MMAB converter into different transmission branches, the optimal combination structure of half-bridge and full-bridge are selected based on the branch powers, forming a simple and efficient TDM modulation technology. Finally, an experimental prototype of a four-port MMAB converter is established and tested. The results demonstrate that the proposed TDM can increase efficiency up to 19.09% compared to SPS, validating the correctness and effectiveness of the theoretical analysis.