Research On Magnetic Coupling Positioning Techniaue Based On Wireless Power And Signal Frequency Division Multiplexing

Wireless power transfer can be classified to two basic types:inductive coupling power transfer(ICPT)and capacitive coupling power transfer(CCPT).Currently,the research on wireless electric vehicle(EV)charging is focused on ICPT.For ICPT,the relative position misalignment between the primary and secondary coils has great impacts on the transfer power and efficiency.Thus,for a practical wireless EV charging system,the detection of position is important.By now,the position dection methods for wireless EV charging include the radio-frequency identification position detection and magnetic coupling position detection.The magnetic coupling position dection is promising due to its high positioning precision and low costs.Besides,wireless power and signal frequency division multiplexing(WPSFDM)is a cutting-edge technique in wireless power transfer.WPSFDM achieves simultaneous power and data transfer by sharing the inductive coupling between the power coils,which can ovecome the common disadvantages of radio-frequency communication methods and simplify the whole system complexityConsidering the principles of WPSFDM and magnetic coupling position dection are both near-field magnetic coupling,a magnetic coupling positioning method based on WPSFDM is proposed in this paper.In the WPSFDM system,four small auxiliary coils are placed on the primary coil to detect the position of secondary coil.The signal transceiver hardwares of WPSFDM are shared by the positioning method.This positioning method can be conducted not only in the condition of power transfer offline but also in the condition of power transfer online,which is appropriate to different working conditions.A prototype of the proposed position detection method was built,which achieved the high-precision dection of the coils relative position.The variation of the coupling coefficient between the auxiliary coil and the secondary coil due to the change of relative position was verified by both Maxwell magentic simulation and experiments.The results of simulation and experiments matched very well,which verifed the feasibility and effectiveness of the proposed position detection method.The experiments of position detection with and without power transfer were conducted and verified.The experimental results showed that the positioning precision was up to 1cm both in the condition of power transfer offline and in the condition of 500W power transfer online.