Research On Monitoring Method Of Insulation Performance Of Electric Vehicle Power Battery Packs

The Chinese government has made a commitment to the world on the medium-and long-term development goals of carbon peaking and carbon neutrality,promoting a comprehensive green transformation of economic and social development while promoting high-quality development,and vigorously developing the electric vehicle industry is one of the effective means to reduce carbon emissions.Compared with fuel vehicles,electric vehicles are driven by power battery packs as the main energy source.With the gradual development of the electric vehicle industry,the voltage level of electric vehicle power battery packs has gradually increased,and the insulation performance requirements of power battery packs and their high-voltage busbars have increased accordingly.In order to ensure the driving safety of electric vehicles and the personal safety of people in the vehicle,the electric vehicle industry has gradually increased the requirements for real-time,accurate and robust monitoring of the insulation performance of power battery packs.Therefore,it is of great significance to study the method of monitoring the insulation performance of electric vehicle power battery packs.This thesis firstly analyzes the electrical system composition of the electric vehicle and the energy exchange process during driving,discusses the reasons and harms of the insulation performance decline of the power battery pack,and analyzes the monitoring principle of the insulation performance of power battery packs.The calculation formula of insulation resistance based on the low frequency injection method model is derived.Secondly,the factors affecting the insulation monitoring accuracy of the low-frequency injection method are analyzed.For the insulation monitoring deviation caused by the frequent acceleration and braking of electric vehicles in driving,a regression analysis method for the sampling curve is proposed,and a corresponding insulation monitoring scheme is proposed.The validity and applicability of the method are verified by building a simulation model and programming calculation.Finally,the influence of the monitoring cycle length of the low-frequency injection method on the reliability of the overall monitoring process is analyzed.For the long time required for the charging and discharging of the Y capacitor,a reduction scheme of the monitoring period is proposed,and a real-time adaptive selection method of the sampling interval is given based on the characteristics of the sampling curve.The research in this thesis is dedicated to improving the accuracy and reliability of the insulation performance monitoring of electric vehicle power battery packs,and provides a reference for the development and design of new electric vehicle insulation monitoring devices and battery management systems.