| According to the latest statistics,the number of motor vehicles in the country reached 319 million as of July 2018.Among them,there are only 1.99 million electric cars and 317 million conventional fuel vehicles.A large amount of exhaust emissions seriously pollute the air,and the huge consumption of fuel accelerates the exhaustion of non-renewable energy.Therefore,as the latest development direction,electric vehicle has attracted people’s attention.Electric vehicle charging ways including charging cable and wireless charging in two ways,the former has developed relatively mature now,so also exposed some limitations,such as power line connection must be used to realize the charge,charge under bad weather easily produce the problem such as leakage,these just for wireless charging can be avoided.The realization of ev wireless charging utilizes the principle of magnetic coupling resonance radio energy transmission technology.This technology can avoid the inconvenience of the high voltage transmission line with frequent pulling,and avoid the occurrence of electricity leakage.However,there are still some technical difficulties,such as the technical difficulties of too low transmission power and efficiency.Therefore,it is of great significance to study the transmission characteristics of the wireless charging system of electric vehicles,safety issues and the correction of charging position of the vehicle parking.The specific contents of this paper are as follows:(1)In the process of ev wireless charging,the coupling coefficient between the energy transmitter and the energy receiver is one of the important factors affecting the efficiency of wireless charging.When charging and parking,it is difficult for the car owner to realize precise alignment between the transmitting coil and the receiving coil through his own feelings,so as to obtain the maximum coupling coefficient and realize fast and effective wireless charging.In this paper,a set of position-based device is designed.The detection part of the device detects the magnetic signal set in the charging space.After the calculation and fitting,the control curve of the running route of the electric vehicle is generated and transmitted to the vehicle control screen to facilitate the driver to charge quickly and effectively.(2)In view of the fact that electric vehicles may be mixed with metal foreign bodies in the wireless charging process,this paper analyzes the influence of metal foreign bodies on the parameters and efficiency of the wireless charging system when placed in the energy transmission area of the wireless charging system.Finite element simulation software used in the study established a flat disc spiral coil electric vehicle charging system 3 d electromagnetic field simulation model,through theoretical analysis and finite element simulation combination of different sizes,different materials of metal foreign body was studied on the wireless energy transmission system of electromagnetic parameters and the influence of efficiency,and experimental verification.The research results show that the mixing of the two metals in the system will produce eddy current effect and magnetic effect,and the magnetic effect and eddy current effect will have different effects on the parameters of the wireless charging system and reduce the system efficiency.The influence is closely related to the size and position of the metal.In addition,the eddy current effect of metal will produce eddy current loss and lead to temperature rise,which is a great potential safety hazard to the charging system.(3)Aiming at the effects of metal foreign body for wireless charging,design a set of visual recognition method using OpenCV,real-time image acquisition of detection area through a fixed camera,complete interested region segmentation to extract,and foreign body detection,at the same time for lighting and other interference caused by error recognition sample for learning,improve the foreign body detection accuracy. |
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