A New Wireless EV Charging System With Integrated DC-DC Magnetic Element

A dc-dc conversion stage is commonly used for a wireless electric vehicle (EV) battery charging system. The dc-dc stage requires a bulky inductor to charge the battery either in constant voltage (CV) or constant current (CC) modes. In this article, a new magnetic structure for the wireless EV charging system is proposed to integrate the dc-dc inductor with the receiver coil on the vehicle side. The proposed structure utilizes the existing core material in the wireless power circuit pads and provides a more compact design and an efficient wireless charger system for EV applications. The proposed magnetic structure is modeled in 3-D, and the finite-element analysis (FEA) results are presented and compared with measurements. Moreover, the effect of the proposed integration method on the wireless charging system performance is investigated, and the results are presented. A 3.3-kW/85-kHz wireless charger is optimally designed and built to evaluate the proposed configuration. Furthermore, the efficiency and the output voltage of the wireless charging system are also measured and compared with the simulation results. The simulation and experimental results show the performance of the proposed structure.