Research On Rapid Detection Method And Evaluation Index Of Electric Vehicle Power Battery

Power battery is one of the most critical component of electric vehicle.When the capacity of battery attenuates to 80% of the initial capacity,it is no longer suitable for use in electric vehicle.It needs to be recovered,otherwise it will directly affect the power,economy and safety of the vehicle.Regulaly rapid detection of power batteries can screen out poor performance or hidden safety risks of the battery for replacement and maintenance,improve driving safety.At present,new energy vehicles follow the same annual inspection policy as traditional fuel vehicles,and refer to the standard of traditional motor vehicles,not testing the performance of the power battery,and some problems and hidden dangers are difficult to find.In view of this,this paper proposes a rapid detection method based on working conditions for pure electric vehicles with the maximum ownership,which can be used to efficiently detect various performance of power batteries and evaluate their main performance indicators.The main research contents of this paper are as follows:(1)The working principle of the most common lithium-ion battery at present was analyzed;The internal decay mechanism of lithium ion battery was studied and the battery parameter changes caused by each decay mechanism were analyzed;The performance parameters of power cell and battery pack were analyzed.The influences of temperature,calendar life,discharge depth and current on the above evaluation factors were studied.(2)Construction of fast detection conditions by analyzing the influence of the power battery data under different nominal test speeds,different loading forces and different loading times on the evaluation indexes;Analysis of factors affecting the rationality of working conditions and the degree of battery parameter variation,The nominal test speed was 50 km/h,the loading force was 600 N and 1400 N,and the loading time was 60 s;The pure electric vehicle is used to verify the rationality of the working condition and the changes of the battery parameters.(3)A fast detection method of power battery based on working conditions was proposed.Including the rapid detection method of vehicle connection and parasitic power fitting and loading of chassis dynamometer,designing the upper computer program of chassis dynamometer;The influence of different voltage sampling accuracy,ambient temperature and SOC value on the detection results was analyzed and the correction method was also studied.(4)Use BAIC New energy EU260 pure electric vehicle for real vehicle test;The performance parameters of various power batteries of the vehicle under the rapid detection method proposed in this paper were tested,and the consistency of single battery and temperature variation were analyzed and evaluated.The capacity decay value of the battery was calculated and verified by a complete charge,The resulting error is 1.25 %.