Load Parameter Joint Identification of Wireless Power Transfer System Based on the DC Input Current and Phase-Shift Angle

This article presents a multiple load parameter joint identification method, adopting only the measured dc input current and inverter phase-shift angle of the wireless power transfer (WPT) system. First, a WPT fundamental-harmonic model is established, considering the effects of the battery and rectifier load. This model can quantitatively describe WPT characteristics and parameter relationships according to the linear superposition of fundamental and harmonic components. Then, the identification method is proposed through the model, which can achieve the joint identification of multiple important load parameters, including battery voltage, equivalent resistance, charging current, and WPT equivalent load impedance. Furthermore, on the basis of the developed WPT prototype, the effectiveness of the proposed fundamental-harmonic model is proved and the parameter sensitivity is discussed. Finally, the proposed identification method is experimentally studied, and the results show that it can achieve high accuracy on the conditions of battery voltage change, phase-shift angle variation, and coil misalignment.