Wireless Charging System for UAV Based on High Offset Tolerance Based on Horizontal Flux Complementarity

This paper presents a design scheme of unmanned aerial vehicle (UAV) wireless charging system with high lateral anti-offset tolerance, effectively solving the problem of output voltage fluctuation caused by landing position offset. The proposed coupling mechanism consists of a transmitting end and two lightweight receiving ends. The transmitting end is composed of two annular coils with a certain interval connected in reverse series, which can form a sinusoidal regularly distributed horizontal magnetic flux above the landing platform. The receiving end adopts a vertically wound solenoid structure and is installed on the left and right landing gears of the unmanned aerial vehicle. Under horizontal offset conditions, the magnetic fluxes captured by the dual receiving ends show complementary changes, which can suppress the fluctuations of the total magnetic flux and thus maintain the stability of the system output voltage. The number of turns and spacing at the transmitting end were optimized by using finite element software, which significantly reduced the mutual inductance fluctuation and expanded the allowable offset range. Based on the proposed scheme, a 300-watt experimental prototype was built. The test results show that the system can still maintain stable output under the condition of $\mathbf{\pm} \mathbf{1 0 0 m m}$ horizontal offset, with a mutual inductance fluctuation rate of approximately 8 % and a DC-DC efficiency of up to 86 %, verifying the effectiveness and practicability of the scheme.