Misalignment and Range Adaptive Wireless Charging System with Constant Current/Constant Voltage Output Based on Coupling Coefficient Estimation

Abstract

Compared with the traditional plug-in charging system, wireless power transfer (WPT) system has the characteristics of electrical and mechanical isolation. A wireless system is proposed suitable for battery charging under misalignment or range variation, and the constant current (CC) and constant voltage (CV) charging are realized by the estimation of coupling coefficient. Firstly, two different operating frequencies based on SS basic compensation structure are designed to realize CC output and CV output respectively. After circuit analysis, CC and CV output cannot be achieved when the position of the secondary coil changes. To solve this issue, when the coil is under misalignment or range variations, the required system parameters are measured, and the coupling coefficient in the charging process is estimated by using the transconductance amplitude equation. Then the corresponding input voltage or working frequency is calculated and fine-tuned. Therefore, the CC and CV charge of the battery can be realized under misalignment or range variation. Finally, experimental results are presented to verify the feasibility and correctness of this method.