Research On High-precision Positioning Technology For Wireless Charging Of Electric Vehicles Based On The Principle Of Electromagnetic Balance

Wireless charging is safe and convenient.Compared with traditional wired charging,unsafe factors such as plug and pull loss and charging line wear can be avoided in the wireless charging.Therefore,wireless charging has been favored by the majority of researchers for the design and use of smart cities.Transmission power and system efficiency are the important indicators to evaluate wireless charging.However,if the transmitting coil and receiving coil cannot be aligned reliably during the charging process,the transmission efficiency will be greatly affected.At present,two categories have been proposed to solve such problem: coil positioning technology to guide the alignment of the transmitting and receiving coils and uniform magnetic field technology to enhance the anti-migration performance of the transmitting and receiving coils.In this thesis,the coil positioning technology has been used to guide the alignment of transmitting and receiving coils.In this thesis,the principle of electromagnetic balance has been used to designed the high-precision positioning system,which the offset position between the vehicle and the charging coil can be quickly located by the premise of ensuring a high precision.The main research includes: the design of the four-coil which used to assist the positioning system based on the electromagnetic balance principle,the exploration of the relevant performance indicators of the positioning system,the extraction and optimization of the key parameters under the condition of multi-coil cross-coupling,and the design and implementation of the whole experiment test of the positioning system according to the results of theoretical analysis.In this thesis,the dynamic parameter variation of the six-coil coupling system used in the positioning process has been deeply analyzed,and the dynamic model has been simplified by a piecewise method.Through theoretical calculation,the efficiency and power variation trends and accurate values of the positioning system have been obtained and a certain reference for system performance evaluation has been provided.In addition,a multi coils coupling model has been established for the extraction and optimization of the key parameters,which are the sampling resistance,balance the placement of the coil and coil coupling coefficient between the several key parameters.These parameters affecting the performance of positioning theory and simulation combined with the research methods,a set of for optimization of the system has been proposed and the optimal range has been gotten.This analysis provides a theoretical foundation for the design and test of the following prototype.At the end of the thesis,a prototype has been designed to verify the performance of the system in the practical applications.The auxiliary positioning system includes two pairs of balance coils arranged on both sides of the receiving coil and hardware detection,includes processing device and display devices,which can be interconnected through communication equipment with other on-board equipment.During the testing process,a optimization algorithm has been proposed and many influencing factors such as the diversification of system display and the unstable drift of positioning data has been considered.Moreover,the positioning effect through the presence or absence of ferrite has been compared,which is an important influencing factor in the wireless charging system.The whole experiment can reach a low power consumption and high positioning accuracy,so the test effect could be very ideal.