A Closed-Loop Constant Current and Efficiency Optimization Control Method for AGV Wireless Power Transfer System Based on Mutual Inductance and Load Identification
Li Xiaofei, Jiang Guangli, Li Zhiheng, Dai Xin, Su Yugang
School of Automation Chongqing University Chongqing 400044 China
Abstract：With the widespread application of AGV in intelligent manufacturing and logistics, a stable and efficient power supply is essential. Enterprises and researchers have proposed applying WPT technology to AGV wireless charging. However, the mutual inductance and load parameter changes lead to system output current and efficiency variations. This paper proposes a closed-loop constant current and efficiency optimization control method for the AGV wireless power transfer system based on mutual inductance and load identification. Firstly, this paper gives the overall structure of the closed-loop constant current AGV wireless power transfer system without a communication link. According to the topological structure of the system, the LCC-LCC and SS resonant compensation topology circuits are analyzed, the parameter identification formulas of mutual inductance MP and MD are derived, and the principle and identification process of the mutual inductance and load are obtained. Since the mutual inductance MP has been identified in advance, the corresponding load RL in the two topological working modes can be further identified by sampling the inverter current. Secondly, according to the mutual inductance and load identification principle, the closed-loop constant current and efficiency control method of the AGV wireless power transfer system is obtained based on mutual inductance and load identification. The closed-loop system structure based on phase-shift control is analyzed, and the specific implementation method of closed-loop control of the output current IL using the feedback detection voltage UD is explained. The load critical points under the LCC-LCC and SS resonant compensation topologies are analyzed, and the load critical point has a one-to-one correspondence with the mutual inductance. A flow chart of system efficiency optimization control based on mutual inductance and load identification is given, and the specific control process of efficiency optimization is elaborated. Finally, an experimental setup is built. The experimental results show that the maximum identification error rates of mutual inductance MP and MD are 2.59% and 6.62% under the two transmission distances of z=3 cm and z=4 cm, and the identification errors of the load identification method under LCC-LCC and SS resonant compensation topologies are both within 1 Ω. The system dynamic response waveforms are tested under LCC-LCC and SS topologies by switching the load and output current reference values. The results show that the system has good steady-state and dynamic performance. A total of three experimental efficiency curves varying with loads are measured. The results show that a load critical value exists, which reverses the system’s efficiency under the two topologies before and after the critical value. The key waveform of the system switching from LCC-LCC topology to SS topology and maintaining constant current output is given, which proves that topology switch determination through load identification is feasible to optimize the system efficiency.
李小飞, 蒋光利, 李志恒, 戴欣, 苏玉刚. 基于互感与负载识别的AGV无线电能传输系统闭环恒流与效率优化控制方法[J]. 电工技术学报, 2025, 40(14): 4418-4430.
Li Xiaofei, Jiang Guangli, Li Zhiheng, Dai Xin, Su Yugang. A Closed-Loop Constant Current and Efficiency Optimization Control Method for AGV Wireless Power Transfer System Based on Mutual Inductance and Load Identification. Transactions of China Electrotechnical Society, 2025, 40(14): 4418-4430.
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2025, Vol. 40 
