A Dual Power Path DC-DC Step Up/Down Partial Power Converter for Electric Vehicle Fast Charging

In this paper, a new DC-DC step up/down partial power converter (SUD-PPC) topology is proposed for fast charging of electric vehicles (EVs). A fast charging (FC) architecture with a variable DC-link voltage is considered to overcome the mode transition challenges in SUD-PPC. The proposed DC-DC topology consists of a three-winding high frequency transformer (HFT), two MOSFET full bridges, one diode full bridge rectifier, and two series LC resonant tanks. The proposed circuit has two operating modes, namely, step-up (SU) and step-down (SD) modes. These modes are achieved through two decoupled power flow paths. The operation of proposed SUD-PPC topology and design method are discussed in detail. A simulation model of the proposed SUD-PPC with the variable DC-link FC architecture is studied for charging a 750 V EV battery at a constant charging current of 100 A. The simulation results are also discussed in detail and the converter performance is validated.