A Minimum Power Circulating Flow and Optimal Dead-time Control Method for GaN Based DAB Converter with EPS Control

Abstract

The extended-phase-shift (EPS) control is proposed to decrease the power circulating flow (PCF) in dual-active-bridge (DAB) DC-DC converters, further improve the efficiency. However, if the calculation of the outer phase shift angle D1 is not accurate due to the complex working conditions of DAB, there will still be a certain amount of power backflow or hard switching states, which will affect the efficiency of the converter. In this paper, a minimum PFC control method based on reverse conduction state detection for DAB converter with EPS control is proposed. According to the conduction state of the body diodes, D1 can be adjusted to the best value which ensured the minimum PCF and ZVS turn-on of the DAB converter. Experimental results show that the proposed method can effectively control the PCF at its minimum point, and all the switches are working under ZVS conditions, thereby the efficiency of the DAB converter is optimized.