A Multiparameter Estimation Method Based on Separable Nonlinear Least Squares for LCC‐Series Wireless Power Transfer Systems

The efficiency and performance of wireless power transfer (WPT) systems are affected by various factors, such as coupling coefficient, quality factor, compensation matching, and operating frequency. However, in practice, the commonly observed circuit parameter drift has not been fully considered in conventional estimation methods, particularly in high‐power applications, and the load characteristics in battery‐charging scenarios are often simplified in analysis. In this paper, a multiparameter estimation method for LCC‐series WPT systems based on separable nonlinear least squares (S‐NLS) is proposed to estimate the receiver resonant frequency, coupling coefficient, and the series compensation capacitance and self‐inductance of the transmitter coil. The proposed method first establishes an equivalent reactive network model based on the no‐load characteristics of the rectifier and then derives the system impedance and power transfer models under. A least‐squares estimation framework is subsequently constructed and solved, and the uniqueness of the minimizer within the investigated parameter ranges is assessed through Hessian‐based convexity analysis. The implementation requires a frequency sweep and uses only transmitter‐side information without dual‐side communication. The proposed method is validated on a hardware prototype of an LCC‐series WPT system for electric vehicles. The experimental results demonstrate that the four target parameters are estimated with a maximum error of 4.4%.