| At present,electric vehicles are popularized rapidly.For convenience and safety considerations,some high-end models provide wireless charging options.In actual application scenarios,due to different parking positions or different sizes of models,the coils position is sometimes misaligned.In outdoor parking lots and residential parking spaces,foreign objects may occasionally enter the charging area.If the type of the foreign objects is metal,the eddy current may cause some safety issues during charging,such as the metal foreign objects to be heated,leading to fire.Therefore,it is necessary to study the problem of position misalignment and metal foreign objects detection in the wireless charging system.This paper researches the detection method for the position misalignment or metal foreign objects based on the detection coil set.Firstly,the influence of positional misalignment and metal foreign objects on the wireless charging coils parameters and magnetic field distribution is analyzed,and a specific form of detection coil set is designed to detect the induced voltage parameters caused by the electromagnetic field changes.Then,based on theoretical analysis and simulation results,a method for detecting of position or metal objects detection through voltage amplitude signals is determined.Furthermore,a hardware circuit is built based on the detection methods,and a software detection algorithm is designed.Finally,experiments verify the effectiveness of the detection method in the presence of non-alignment or metal foreign objects.Experimental results show that the detection coils and detection method designed in this paper are used for metal objects detection,the smallest area of metal objects that can be detected accounts for about 1.2% of the area of the power coil;when used for detection of position,the detection coils can be used for compare the voltage amplitude,the position of the power coils will be judged by data comparison. |
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