Light Load Efficiency Improvement Method for GaN-Based DAB Converter with Hybrid Discontinuous Current Mode

Conventional phase-shift controlled dual active bridge (DAB) converters which operate in discontinuous current mode (DCM) are hard to realize the zero-voltage switching (ZVS) due to the light load. This paper proposed an efficiency improvement method for the DAB converter with fix-frequency hybrid discontinue current mode (HDCM). By adopting the HDCM control method, synchronous rectification and wide load range ZVS of switching devices are realized simultaneously without changing the components of the conventional DAB power stage in DCM. Besides, to further improve the conversion ratio and efficiency, the voltage-doubled rectification (VDR) is adopted. The HDCM implementation method with a digital signal processor (DSP) is proposed. A 200W laboratory prototype is designed to validate the correctness of HDCM. Compared to the conventional DAB converter which operates in DCM, experimental results demonstrate that the efficiency was increased 1.2% at 10% rated load.