A Dual-Layer Receiver With Low Interlayer Voltage Stress and High Power Density for EVs Wireless Charging System

The wireless charging system for electric vehicles is convenient and reliable, but its transmission power is lower than that of plug-in charging. To improve the competitiveness of wireless charging, it is necessary to improve the power density of the receiver. However, the power volume density of the single-layer receiver in SAE J2954 WPT3/Z3 is only 3.12 W/cm³, making it difficult to achieve high power transfer in a limited space. In this article, a dual-layer receiver with an M-core and an alternating cross-stacked coil is proposed. Under the condition of constant volume and 28.95% increase in core usage, the proposed receiver improves the mutual inductance and coupling coefficient by about 18.8% and 5.68%, compared to the flat-core dual-layer receiver. Additionally, it decreases the maximum interlayer voltage by 81.21% compared to the existing internal and external co-direction dual-layer coil. Finally, a prototype with an output power of 11 kW was built, and the coupling performance and interlayer voltage of the receiver proposed were verified. A wireless power transmission with a transmission distance of 230 mm and a receiver power volume density of 4.58 W/cm³ was successfully achieved.