An Improved Compensation Method Reducing Displacement Current Loss for Multilayer Coils in IPT System

Dual-layer or multilayer coils are often used to increase the power density of inductive power transfer systems. However, compared to single-layer coils, multilayer coils suffer from additional loss caused by interlayer displacement current (IDC), which can reduce system transmission efficiency. Therefore, this letter establishes a general mathematical model for IDC loss in multilayer coils regardless of whether the adjacent layers are symmetric. The traditional centralized compensation capacitor is split into two capacitors (interlayer and auxiliary capacitors), and a novel parameteric design method for the interlayer capacitor is proposed to optimize the IDC losses. The auxiliary capacitor is used to adjust the resonance state of the circuit. The experimental results show that compared to the traditional method, the prototype with the double-layer symmetrical coil achieves efficiency improvements of 0.5% under light load and 2.27% under heavy load. The double-layer asymmetrical coil prototype achieves efficiency improvements of 0.58% under light load and 2.11% under heavy load compared to the traditional method.