Welding Defect Detection Of Power Battery Module Busbar Based On Ultrasonic Phased Array

In recent years,with the continuous expansion of the new energy vehicle market,the number of electric vehicle safety accidents has increased.Most of the electric vehicle accidents are caused by the quality of the power battery,and in addition to the battery,the quality of other components of the electric vehicle cannot be ignored.Therefore,it is very important to detect the relevant components of the new energy vehicle power battery.The power battery busbar is an electrical connector with metal copper and metal aluminum as the base material.It is made by ultrasonic welding and has excellent electrical conductivity.It is the contact point when the battery is charged and discharged.As an important component in the power battery module,the tensile strength and electrical performance of the busbar are its two very important indicators.If the busbar breaks or falls off,it will affect the power performance of the electric vehicle at light level,and cause a short circuit in the circuit inside the battery module,causing the battery pack to burn.In order to prevent safety accidents caused by the breaking and falling off of the power battery busbars,it is necessary to conduct a full inspection of the welding defects of the busbars.However,the current main method is the destructive tensile test,which can only be carried out by random inspection and cannot meet the requirements of full inspection.In this paper,a new method for nondestructive testing of busbars based on ultrasonic phased array C-scan is proposed.Firstly,the principle of ultrasonic reflection and the principle of ultrasonic phased array C-scan imaging are introduced.The phased array C-scan image processing technology is studied,and the conversion relationship between acoustic reflectivity and acoustic impedance is given.The adaptive double-threshold segmentation algorithm and the lattice boundary region extraction algorithm are used to extract the image feature area,the neighborhood search fast algorithm is used to locate the welding area of ?the C-scan image,and the Gaussian blur and the maximum inter-class variance method are used to further analyze the welding area.The contour is extracted,the solder joint area is presented graphically,and the evaluation indicators such as the weld scar area,the bonding area,and the number of solder joints are calculated.Finally,the fuzzy evaluation model is used to comprehensively evaluate the workpiece to be tested.Ultrasonic testing software was developed,and the testing results were compared and analyzed with the tensile test results.Sixty busbar samples were selected for testing and compared with the tensile test.The experimental results show that the detection accuracy is greater than 95%.The samples were tested repeatedly,and the consistency was greater than 98%.The average detection time of a single workpiece is less than 2.70 seconds.