Analysis and Design of a Wide Output Voltage Range Battery Charger for e-Mobility Applications

The electric vehicle (EV) battery pack voltages typically range from 120 to 450 V, however, the traditional battery charger's operating voltage range is limited. The existing wide voltage range battery chargers employ a front-end diode bridge rectifier followed by a buck-boost derived converter as an ac-dc conversion stage and coupled to an isolated dc-dc converter, resulting in a discontinuous input current and higher power losses due to more semiconductor devices in the conduction path. Furthermore, the utilization of traditional controllers to control these battery chargers produces current transients during mode transitions. This article proposes an isolated bridgeless wide output voltage range battery charger for universal EV charging applications. The proposed charger's operation principles, modeling, and design considerations are discussed in detail. A dual-loop controller for boost and buck operations with a smooth transition logic is designed to accomplish a seamless mode transition. The presented analysis and the design are verified through MATLAB simulations and experimental studies from a 1.3-kW field programmable gate array controlled silicon carbide laboratory prototype. Finally, the superiority of the proposed charger is demonstrated by comparing it with existing wide-voltage range battery chargers.