A Simplified All-ZVS Strategy for High-Frequency Triple Active Bridge Converters with Designed Magnetizing Inductance

The triple active bridge (TAB) converters that integrates the on-board charger and the auxiliary power module is ideally suited for producing a high-power density electric vehicle (EV) charger. As the power coupling among each port complicates the TAB's mode analysis, it is challenging to avoid a compromise with high-efficient operation and the wide-applicability of soft-switching operation in the TAB modulation technique. In this work, the influence of the transformer's magnetizing inductance is introduced into the analysis of the TAB converter for simplifying the realization of zero voltage switching (ZVS), and in this way, the power conversion efficiency of TAB operating in high-frequency can be improved. Drawing on the working principles of a single dual active bridge (DAB) converter and the linear superposition theorem, a simplified four-phase modulation (FPM) scheme for the TAB converter is proposed in this article, which is computationally stress-free, featuring low switching and conduction loss characteristics. By combining the FPM scheme with the tuning of the magnetizing inductance value, the ZVS operation of all switches can be readily achieved without imposing extra computational burden. This is particularly advantageous for time-intensive scenarios such as those found in the application of EVs. In addition, the ZVS process of the TAB converter is thoroughly studied and unified to simplify the calculation of ZVS current and required dead time, enabling the identification of the optimal magnetizing inductance value. The proposed optimization solution is introduced, studied, validated, and benchmarked in a 2.5 kW/100 kHz SiC-based TAB prototype, whose operating parameters are tailored to EVs application and peak efficiency reaches 96.3% at a partial load.