Constant Current Charging and the Maximum System Efficiency Tracking for Wireless Charging Systems Employing Dual-side Control

The system efficiency and charging current highly dependents on load conditions, which varies in a wide range for practical applications, such as the supercapacitor charge. To achieve the maximum system efficiency (MSE) tracking and constant current (CC) charging, this paper designs the dual-side controlled wireless power transfer (WPT) system. The fundamental harmonic analysis based on the mutual inductance model is built to illustrate the system characteristics. Based on the algorithm of perturbation observation, the primary-side Buck converter realizes the MSE tracking through measuring the minimum system dc input current. The secondary-side PI controlled semi-active rectifier achieves CC charging for the supercapacitor. The simulation results verify the proposed control method. During the CC charging of 2 A, the system efficiency is significantly improved.