| Magnetic Coupled Wireless Power Transfer(MC-WPT)technology uses magnetic field as the power transmission medium to realize the wireless transmission of power from the power source side to the load side.Compared with the traditional power supply mode,it has the advantages of safety,flexibility,reliability and easy maintenance,and has been paid more and more attention by experts and scholars.In practical applications,the wireless charging area is easy to fall into foreign objects such as metals or organisms.The metal will produce eddy current in the magnetic field,which will cause potential harm by rapid heating,and will change the relevant parameters,affect the normal operation of the system;organisms will be affected by radiation in the magnetic field,which may cause tissue damage.Therefore,it is necessary to detect metal and biological foreign objects in the charging area to ensure the safe and reliable operation of the system.In addition,in order to achieve better power transmission effect and improve the robustness of the system,it is necessary to exchange information between transmitter and receiver to achieve closed-loop control at the same time of power transmission.At present,many scholars have carried out research on foreign object detection(FOD)technology of MC-WPT system and parallel transmission technology of power and signal,and put forward some solutions,but generally need to add both FOD device and signal transmission device.In this paper,a FOD and signal transmission device based on partially shared coil is proposed,which integrates FOD and signal transmission.It ensures the safe and stable operation,reduces the cost and volume of the system,and promotes the application and popularization of MC-WPT technology in engineering.Based on MC-WPT system,this paper aims to find a device and method which can not only complete foreign body detection,but also realize signal transmission.On the premise of not affecting the power transmission,the research work is aimed at reducing the crosstalk between power and signal,the crosstalk between signals and optimizing the system structure.In this paper,the advantages and disadvantages of several common FOD methods and parallel transmission methods of power and signal are analyzed.Finally,according to the actual project requirements,the overall scheme of the system is determined.A pair of coupling coils are added to realize FOD and signal transmission,and a part of FOD coils are used as a signal coupling coil,thus forming a relatively independent circuit of FOD and signal transmission,and the corresponding hardware circuit is designed.On the basis of the determined system topology and the designed circuit,the mathematical models of FOD circuit,signal transmission channel and interference channel are established respectively,and the mathematical expressions of FOD and signal transmission carrier attenuation and various crosstalk are given.Combining with the constraints of power crosstalk and FOD characteristics,the design method of parameters and program of FOD are provided.Finally,based on the established mathematical model,the frequency domain simulation analysis is carried out by using MATLAB,and the system circuit is simulated by using Multisim.The simulation results show that the crosstalk of each interference link can be reduced to the required range,and the designed circuit can also meet the requirements of FOD and signal transmission.A system experimental device was built to carry out the experiment.In the experiment,the device realized the detection of an organisms and metals between the coupling coils,and the stable transmission of signal with a highest baud rate of 82 kbps at the same time of power transmission. |
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