Design and Verification of Adaptive CC/CV Mode Switching Wireless Power Transfer System for UAVs Based on High Switching Frequency Single Switch LC Inverter

This paper presents a magnetic coupling-based adaptive CC/CV mode switching wireless power transmission system based on the high frequency single switch LC inverter for small and medium-sized Unmanned Aerial Vehicles (UAVs) that has anti-offset capabilities and can switch between constant voltage charging mode and constant current charging mode smoothly. Compared to the popular wireless charging systems for rotor-based UAVs, this design utilizes the principle of underdamped resonance to achieve high-frequency inversion through a single switch LC topology. The circuit has a smaller size and higher reliability. Additionally, the compensation network of the coupling coil of the receiver side can achieve constant voltage/current topological switching, avoiding the cumbersome communication process between the primary side and secondary side of the coupling structure. Furthermore, to address the issue of transmitter-receiver coil misalignment in practical applications for UAVs, this paper optimizes the circuit parameters to reduce the sensitivity of output power to coupling coefficient based on the proposed topological structure. This approach could help to reduce the output power fluctuations and achieve strong anti-offset capacity. Finally, a 100 W prototype is built with a 25 V input voltage to verify the design. Experimental results show that when the coupling coefficient fluctuates within the range of 0.25 to 0.35, the output power fluctuation of the prototype is less than 6.5%. The 92% peak efficiency is achieved with the simple topology and open loop control method.