A New Bidirectional Three Port DC-DC Converter for Dual Auxiliary Voltage in EV Application

This paper proposes a new isolated bidirectional three-port DC-DC converter (TPC), which combines an isolated dual active bridge converter (DAB) and a non-isolated dual floating boost (DFB) converter, named the three-port current fed dual floating DAB converter. Due to the required power of auxiliary load in the vehicle is increased rapidly for autonomous and entertainment. Dual auxiliary voltage (48V/12V) system is introduced for reducing the burden of high current. Additionally, the operating duty moves far from 0.5 due to the voltage ratio. By utilizing the high voltage gain characteristic of the DFB converter, the duty range of the proposed converter is around 0.5, which reduces the filter size, turns off current, circulating current, and increases power transfer capability from the high voltage side. Furthermore, a lower voltage rating can be used, featuring lower R_DS,on for reduced conduction loss. A 600W, 140kHz, 800V-48V-12V laboratory prototype of the proposed TPC has been built to validate the effectiveness of the performance and the theoretical claims.