Recently, Electric Vehicle (EV) on-board charging systems have been designed to achieve high power level, high efficiency and reliable battery charging. However, it brings the complexity in the design process. This paper proposes a comprehensive control strategy for GaN-modular charging system that can implement a precise constant current- voltage (CC/CV) charging control and an excellent current sharing capability among paralleled modules. Moreover, the efficiency of the proposed system is improved at a wide range of charging power by adopting a proper load shedding scheme. The circuit configuration consists of three individual modules of two-stage converter units, in which a totem pole power factor correction (PFC) and an isolated phase shift full bridge (PSFB) are selected as the front-end and back-end converter respectively. The average current mode control employed in PSFB stage not only maintains the constant current charging, but also automatically achieves current balancing among converter modules. The theoretical analysis and simulation results of a 11kW GaN On-Board Charging (OBC) system have been presented to demonstrate the feasibility of proposed control method.
|Status||Unpublished - 15 jun 2021|