A Unified Modeling Approach for Steady State and ZVS Analysis of a Triple Active Bridge Converter

This paper outlines a systematic methodology based on the superposition principle to develop a unified model for a Triple Active Bridge (TAB) converter. The proposed model is valid for all operating modes and modulation strategies of the TAB converter. The proposed model accurately predicts the AC port and DC port currents in a TAB converter, and it is used to compute performance metrics of the TAB converter, such as the peak and RMS currents at the AC ports and the average currents at the DC ports. The proposed model is further used to analyze the Zero Voltage Switching (ZVS) boundaries of the TAB converter. One of the features of the proposed model is that it incorporates the impact of transformer magnetizing inductance on the AC and DC port currents as well as the ZVS boundaries of the TAB converter. The model's accuracy is verified against extensive switching circuit simulations for various operating conditions. The model is used to design the TAB converter parameters. Experimental results from a TAB converter laboratory prototype are presented to showcase the impact of magnetizing inductance on TAB converter performance and ZVS boundaries. The soft-switching boundaries predicted by the model are experimentally verified and efficiency results are presented to highlight the benefits of achieving ZVS.