Analysis and design for constant current/constant voltage multi‐coil wireless power transfer system with high EMF reduction

Abstract

Abstract The investigation on the constant current (CC)/constant voltage (CV) charging for the electric vehicle wireless power transfer (WPT) system has been widely conducted. However, the CC/CV performance under misalignment cases has been scarcely studied especially for the multi‐coil WPT system. The resonant tank compensation methodology for the exciter‐quadrature‐repeaters (EQR) transmitter‐based multi‐coil WPT system is studied to achieve high power factor CC/CV charging with low leakage flux over ±150 mm lateral misalignment range. The EQR transmitter consists of one small exciter coil powered by a single full bridge inverter and two larger decoupled quadrature repeater coils which are magnetically coupled to the exciter coil. A variable switched capacitor is applied on the exciter side to maintain a high power factor in the CV mode. A 3‐kW experimental setup with a 200 mm nominal vertical distance was built and a three‐coil WPT system with a single large repeater coil is chosen as a comparison. Experimental results show that the EQR transmitter‐based WPT system achieves 92% coil‐to‐coil efficiency and reduces the leakage flux density by 70% compared with the existing three‐coil system in the CV mode at 150‐mm lateral misalignment.