Variable Inductor Control for Misalignment Tolerance and Constant Current/Voltage Charging in Inductive Power Transfer System

In a wireless power transfer (WPT) system, not only the mutual inductance variation but also the self-inductance variation can occur under the misalignment condition. In light of the unmanned aerial vehicles (UAVs), the variation of the secondary self-inductance and mutual inductance are significant under the misalignment condition. In order to stabilize the output voltage and current and achieve near-zero phase angle (near-ZPA) of the input impedance, a variable inductor control is presented in this article, which regulates the inductance of the secondary side by adjusting the dc bias current under large $k$ variation. The proposed control method does not need any auxiliary circuit, and constant current-constant voltage (CC-CV) charging can be achieved by controlling the duty cycle of the boost converter. To verify the proposed control method, a 500-W prototype was set up in the laboratory, and the variable inductor control method ensures a stable output voltage and current with horizontal and vertical offsets of 200 and 92 mm, respectively. Additionally, communication is not needed between the primary and secondary sides, and the results show that the maximum efficiency is 92.9%, which is 2.3% higher than the conventional dc–dc regulation method.