Switching Control Strategy Of Multi-transmitter WPT System Based On Position Estimation

Wireless Power Transfer(WPT)technology,as an emerging non-contact energy transmission method,gets rid of the shackles of charging wires and has the advantages of safety,flexibility and convenience.It is used in electric vehicles,medical equipment,and drones.The occasion has a wide range of application prospects.However,in actual power supply occasions,the uncertainty of the relative position of the receiving(RX)coil and the transmitting(TX)coil causes the mutual inductance and efficiency of the system to be affected.In order to solve the impact of coil misalignment on the system performance,scholars at home and abroad have successively proposed a multi-transmit WPT system.Based on the position of the RX coil,the switching control of multiple transmitting coils can improve the system’s tolerance to coil misalignment.For this reason,the research on the position estimation of the RX coil of the multi-transmit WPT system is of great significance for improving the efficiency and robustness of the system.For the research of RX coil position estimation,traditional methods adopt wireless communication method and electromagnetic parameter identification method for detection.The wireless communication method is susceptible to interference from external electromagnetic signals,and the reliability is not high.Meanwhile,it is difficult to acquire the mutual inductance parameters online in engineering practice.Therefore,the paper focuses on the problem of obtaining the position of the RX coil.By analyzing the relationship between the electrical information of the primary side and the parameters to be estimated,a switching control method for the multi-transmit WPT system based on the position estimation of the RX coil is proposed,realized the online identification of RX coil position,improve the misalignment conditions system transmission efficiency.The primary study contents completed as follows:(1)Analyzed transmission principles and switching control methods of three multi-transmit WPT systems,deduced the functional relationship between system efficiency and lateral misalignment parameters.Meanwhile,a switching criterion for multi-transmit WPT systems based on the position of the RX coil is established.(2)Proposed a receiving coil position estimation model based on a machine learning(ML)algorithm,in which the transmission distance,primary current,and system efficiency are used as the input factors of the estimation model,and the position of the RX coil is used as the label.Through simulation and comparison,the training accuracy and generalization ability of the three position estimation models of Error Back Propagation(BP)algorithm,Support Vector Regression(SVR)algorithm and Bayesian regression algorithm are analyzed.The results show that the estimation and generalization ability of BP algorithm is better than SVR and Bayes algorithm.Meanwhile,analyzed the good ability of BP algorithm to identify the misalignment position of RX coil under different working conditions.(3)Proposed a multi-transmit WPT system switching control strategy based on the position estimation of the RX coil,and the BP position estimation algorithm is designed using Verilog language.On this basis,a multi-transmit WPT system hardware platform was built using FPGA.The experimental results verified the effectiveness of the position estimation method and improved the system efficiency and stability.