An L-S/N IPT System with a Lightweight Receiver and Primary-Side Tuning and Constant-Current Control for Misalignment-Tolerant UAV Wireless Charging

To address receiver-side weight constraints, resonance detuning, and output-current variations caused by coil misalignment in unmanned aerial vehicle (UAV) wireless charging, this paper proposes an inductive power transfer system employing an inductor-series/none (L-S/N) compensation topology and primary-side-sensing-based constant-current control. The topology eliminates the secondary compensation network, while its tuning conditions and constant-current characteristics are derived using a T-network immittance-inverter model. The mutual inductance is identified from two primary-current magnitude measurements without secondary-side sensing or wireless communication. A switched capacitor controlled by pulse-width modulation (PWM) is then used to restore resonance, and inverter phase-shift control compensates for the output-gain variation caused by changes in mutual inductance. In addition, a three-layer stacked magnetic coupler is designed to improve mutual-inductance stability under horizontal misalignment. Experimental results demonstrate stable operation at different misalignment positions, achieving a DC-to-DC efficiency of 84.3% at an output power of approximately 98 W.