Voltage/Current Doubler Converter for an Efficient Wireless Charging of Electric Vehicles With 400-V and 800-V Battery Voltages

The lithium-ion battery of an electric vehicle (EV) is typically rated at either 400 or 800 V. When considering public parking infrastructures, EV wireless chargers must efficiently deliver electric power to both battery options. This can be normally achieved by regulating the output voltage through a dc-dc converter at the cost of higher onboard circuit complexity and lower overall efficiency. This article proposes a wireless charging system that maintains a high power transfer efficiency when charging EVs with either 400- or 800-V nominal battery voltage at the same power level. The control scheme is implemented at the power source side, and only passive semiconductor devices are employed on board the EV. The presented system, called voltage/current doubler (V/I-D), comprises two sets of series-compensated coupled coils, each of them connected to a dedicated H-bridge converter. The equivalent circuit has been analyzed while explaining the parameters' selection. The analytical power transfer efficiency has been compared to the one resulting from the conventional one-to-one coil system at 7.2 kW. For the same power level, the dc-to-dc efficiency of 97.11% and 97.52% have been measured at 400-V and 800-V voltage output, respectively. Finally, the functionality of the V/I-D converter has been proved at both the even and uneven misalignments of the two sets of coupled coils.

Automated summary

This article proposes a wireless charging system that efficiently charges electric vehicles (EVs) with either 400V or 800V batteries at the same power level. The system only uses passive semiconductor devices on board the EV and consists of two sets of series-compensated coupled coils and dedicated H-bridge converters. The power transfer efficiency of the system is compared to a conventional one-to-one coil system at a power level of 7.2 kW, resulting in dc-to-dc efficiencies of 97.11% and 97.52% for 400V and 800V voltage outputs, respectively. The functionality of the V/I-D converter is proven for both even and uneven misalignments of the coupled coils.