Null-Coupled Magnetic Integration for EV Wireless Power Transfer System

Wireless power transfer (WPT) for electrical vehicles (EV) has become increasingly popular because it is safe and convenient. Double-sided inductor-capacitor-capacitor (LCC) compensation network is suitable for WPT systems. A more compact structure can be realized by integrating the magnetic components in the LCC compensation network into the power-transferring coils. Based on the earlier study that double D (DD) coil and unipolar coil couple zero power, two types of null-coupled magnetic integrated structures are proposed. A feasible structure is chosen by analyzing the characteristics of these two structures. The impacts of the extra couplings due to magnetic integration are modeled and analyzed. Results show that the magnetic integration slightly changes the coil currents, transferred power, and power factor but the variations can be reduced by properly designing the coils. The proposed structure and analysis are validated by experiments on a prototype.