Dual-loop Control Based Receiver Resonant Frequency Tracking and Mutual Inductance Identification in Wireless Power Transfer System

This paper introduces a novel approach for simultaneously achieving receiver resonant frequency tracking and mutual inductance identification in a wireless power transfer (WPT) system. This method relies solely on the primary-side controller and a switch-controlled capacitor (SCC). The proposed technique utilizes a dual-loop structure, where a gradient descent (GD) controller functions as the outer loop, and zero-phase angle (ZPA) control by the SCC serves as the inner loop. This control-based identification method can accommodate parameter fluctuations on the primary side and act as an auxiliary detection circuit for SAE J2954-compatible devices prior to high-power charging. Both simulations and experiments have been conducted to validate the proposed method. Compared to the slow identification speeds of traditional optimization algorithms, this approach can complete the identification process within 200 milliseconds, achieving maximal identification errors of 1.21 µH for mutual inductance and 1.47% for receiver resonant frequency.