Research On UAV Multi-receiver Coil WPT System

Multi-rotor UAVs have been widely used in military and civilian because of the advantages of small size,flexibility and easy takeoff and landing.However,due to battery bottlenecks,multirotor UAVs usually have a short range and limited endurance,making it difficult to meet some long-time working requirements.The wireless charging technology is easy to be unattended and can be more flexible to provide electrical energy supply for UAVs,which fits perfectly with the characteristics of autonomous operation of UAVs,so wireless charging technology has a broad application prospect in the field of UAVs.Unlike other applications of wireless charging technologies,the system design of UAVs is different due to their special structure.In this paper,characteristics of wireless charging systems for UAVs are summarized based on existing literature and the circuit is designed according to these characteristics.Firstly,basic circuit framework of multiple receiver coils is given according to the characteristics of wireless charging technology for UAV.And transmitting and receiving coils are designed corresponding.After that,a modeling analysis of different compensation networks is presented,mainly the LCC-P compensation topology,and its resonance conditions and output characteristics are obtained,which provide the corresponding direction for the primary side control.Then the circulating current problem brought by the parallel connection of multiple receiving coils is analyzed,and the method of shift and phase control is adopted to solve this problem.In order to minimize the weight of the UAV,the primary side control method is adopted which can complete the derivation from the primary side parameters to the output current amplitude and phase of the secondary side,and the design of the main circuit parameters and the system control flow are carried out specifically.The system is modeled and simulated in MATLAB/Simulink,and the correct feasibility of the control method adopted by this system is verified.Finally,combined with practice,the wireless charging system of UAV is designed,and the corresponding experimental platform is built.Due to the difficulty of high-frequency phase sampling and limited time,only open-loop experiments are conducted in this paper,and the experimental results show that the primary side control method designed in this paper can calculate the mutual inductance value relatively and keep the amplitude and phase of different channels constant,which solves the circulating current problem existing in the parallel system and improves the charging efficiency of the UAV.The designed circuit structure meets the requirements of the lightweight UAV,and the whole system has strong practicality.