Coupling Estimation of Wireless Power Transfer Systems with Constant Voltage Load Through Zero-Phase Angle Frequency

This paper proposes a coupling estimation method for wireless power transfer (WPT) systems with constant voltage load (CVL). The method involves calculating the zero-phase angle (ZPA) frequencies, which are found to be solely dependent on the coupling and independent of the output voltage in WPT systems with CVL and frequency bifurcation. By leveraging this unique characteristic, a self-oscillation method is employed to automatically locate the ZPA points, enabling rapid and accurate coupling estimation. The proposed method is highly effective across the entire range of couplings and does not require wireless communication, additional hardware, or complex calculations. Simulation results are provided to validate the effectiveness of the proposed method.