Universal Off-board Battery Charger for Light and Heavy Electric Vehicles

Amidst growing environmental and energy concerns, electric vehicles (EVs) are potential solution for reducing carbon emission. All-electric green energy objectives heavily rely on standardization of electric vehicle service equipment (EVSE), associated protocols, smart chargers and battery technology. However, no generic approach for EVSE for charging different categories of electric vehicle exists. Therefore, in this paper, an off-board unidirectional conductive type DC fast charger for light and heavy electric vehicles is presented. The converter is adaptable for charging of light as well as heavy electric vehicles. The proposed charger is based on resonant series converter with adaptable restructured multiplier rectifier. The restructuring element for adaptable rectifier is a simple bi-directional switch. The doubler configuration is recommended for light electric vehicles (400V Class) while quadrupler configuration is recommended for heavy electric vehicles (800V Class). In this paper, both the configurations and their associated operation modes are explained with respective waveforms. Further, all semiconductor switches and rectifier diodes are naturally soft switched owing to resonant converter above resonant frequency operation for minimizing losses. The charging rates and power levels can be scaled up or down by adopting modular approach. To validate the presented theoretical analysis, a 1.25 kW hardware prototype is designed and tested in the laboratory and experimental results are presented.