Multi-transmit Coils Structure Design And Its Switching Control For Wireless Power Transfer System

Wireless power transfer technology(WPT)has been drawing wide attention to the scholars and manufacturers both at home and abroad due to its` better performance than traditional wired power transmission method.Transfer efficiency is an important factor,which is used to evaluate the system performance.Coil misalignment is the one of crucial factors to impact on the transfer efficiency of WPT.Coil misalignment is inevitable in many practical situations.Nowadays research show that the efficiency will degrade when coils are misaligned,even the conditions of resonance and impedance matching are satisfied.Typically the coil structure is fixed,it is not convenient to adjust the working area adaptively.The ability to improve transfer efficiency is limited by coil misalignment.Thus,from the aspect of coil structure to increase transfer efficiency when coils are misaligned has a great meaning.To reduce the effect of the coils misalignment on system transmission efficiency,a Multi-transmit Coils Switchable Wireless Power Transfer(MCS-WPT)based on the biomimetic principle is proposed in this paper.The transmitting terminal is made up of 13 hexagonal coils resembling a turtle shell,they constitutes three different transmit areas.The coil misalignment between transmitter coils and receiver coils can be rudced by switching control.The mutual induction can be enhanced.The simulation and experimental results verify the validity of the coil structure.It improves the transmission efficiency of WPT system.The main research works in this paper are given as follows:Firstly,the design of system structure and the research of coil misalignment characteristics for MCS-WPT are illustrated.The coils combination structure and compensation topology of transmitting terminal and the structure and compensation topology of receiving terminal are discussed.Then,the affection of coil misalignment on mutual induction and primary current as well as the efficiency are analyzed.Secondly,the control strategy of MCS-WPT system coils is put forward.The bipolar control strategy of inverter is briefly introduced,then the logic structure and position recognition method of the coils are emphasized,coils switching regulations are also made.The feasibility of improving the transmitting efficiency by switching the working area of the transmitting coil is demonstrated in simulations.Thirdly,the prototype of MCS-WPT is developed and tested.The design process of prototype is described in terms of hardware design and software design.The effectiveness of position recognition method and the improvement of transmitting efficiency are validated by the experiment of position recognition and switching control.