Real-Time Parameter Estimation of Wireless Power Transfer Systems With Large Receiver Tuning Tolerance

This article proposes a real-time, transmitter-side parameter estimation method for a series-series (S-S) WPT system with large receiver tuning tolerance. A 60-degree phase-shifted modulation is employed to suppress the third-order harmonic voltage generated from the transmitter (Tx). A unique online training algorithm is developed to determine the unknown parameters, including the coupling coefficient, equivalent load resistance, and load reactance before the rectifier. This training algorithm iteratively adjusts the parameters to minimize the error between a theoretical model and real-time measurements of the transmitter's fundamental input impedance and reflected third-order harmonics. The results are used to derive the output voltage and current. A practical prototype was built and tested with varying coupling (0.4 to 0.7) and loads (20 to 80 Ω). Experimental results show accurate estimation of all parameters and variables with a time delay under 30 ms.