Modular Series Transmitter Array Based Wireless Charging System for Multiple EV Charging Application

This article presents a novel wireless electric vehicle (EV) charging system to charge multiple EVs simultaneously and independently. The system uses a modular series transmitter array (STA) in which each channel operates as an independent charging port. A channel can be dynamically activated or deactivated as per the vehicle availability without affecting the output power of other channels. In the STA all channels share a common LCL compensation circuitry. Such a topology renders constant current (CC) in STA regardless of number of EVs being charged, thereby simplifying the design constraints of the coils. The system is powered by a single electric vehicle supply equipment (EVSE) which provides optimization benefits in terms of device count, versatility, power density, and overall cost when compared to dedicated charging interfaces. A detailed system level analysis is presented including system parameter design and optimal load conditions for maximum efficiency in each channel. A tuning method for compensation parameters is presented to realize zero voltage switching (ZVS) in the primary inverter for the entire range of load. Finally, a laboratory prototype is developed with two channels to verify the effectiveness of the proposed wireless power transfer (WPT) system. Results show that both channels are capable of delivering power simultaneously and independently without cross regulation problem in terms of load and coupling variation. The system achieves a maximum efficiency of 95.7% for a total output power of 4 kW, with equal load on both channels.