Modulation Strategy of Three-Phase Dual-Active-Bridge Converter Using SiC-MOSFET for Improving Light Load Condition

In this paper, a modulation strategy for a three-phase dual-active-bridge (3P-DAB) converter based on SiC-MOSFET is proposed to improve the light load efficiency for LVDC applications. The 3P-DAB converter is popular in high-power applications because of its low conduction loss with the interleaved construction, low switching loss with zero voltage switching (ZVS) capability, and seamless control capability in bi-directional power flows. In addition, compared with the single DAB converter, it can reduce the filter size, which increases the power density of the converter. However, the conventional power control method for the 3P-DAB converter, which is called the single phase shift modulation (SPSM), is not effective due to its ZVS failure in the light load condition with practical approach. In this paper, the modulation strategy is proposed based on the hybrid control, which consists of the duty and phase-shift controls for modulating SiC-MOSFETs. A 3-kW prototype converter is implemented and tested to verify the effectiveness of the proposed methods.