Parameter Estimation Using Total Harmonic Distortion in a WPT System

Wireless power transfer (WPT) systems are widely used in various applications due to their convenience and efficiency. However, the performance of WPT systems can be significantly affected by misalignment and load variations. This letter proposes a method to estimate mutual inductance (M) and load resistance (${{R}_L})$ in WPT systems using total harmonic distortion (THD) of input current. A numerical method to estimate these parameters has been developed by deriving an analytical relationship between THD, M, and ${{R}_L}$. Experimental validation demonstrates that the proposed method provides accurate estimates of M and ${{R}_L}$ under varying conditions by only using transmitter current, with maximum estimation errors of 5.1% for M and 3.6% for ${{R}_L}$ when estimated separately by keeping the other parameter constant. The proposed method is extended to simultaneously estimate M and R_L with a maximum estimation error of 4.9%. This method can be adopted for real-time monitoring and control strategies, such as frequency control, system identification, and diagnostic applications, in WPT systems.