Real-Time Parameter Estimation in SS Compensated Wireless Power Transfer Systems Considering Nonlinearity of the Diode Rectifier

A real-time parameter estimation method is proposed for series-series (SS) compensated wireless power transfer (WPT) systems in this paper. Unlike conventional approaches that model the input impedance as purely resistive, a more accurate inductive model is established with the consideration of the nonlinearity of diode rectifiers. Based on the derived model, the key system parameters can be accurately estimated in real time, by simply sampling the primary compensation capacitor voltage and the input voltage. This method eliminates the need for bilateral communication and causes zero interference on normal system operation as no prior or special actions are required. The estimation procedures are presented in detail and verified on a prototype. Experimental results demonstrate the feasibility of the proposed method, which achieves a high-accuracy estimation of the coupling coefficients and output voltage in 131 μs.