Research On Insulation Detection Of Electric Vehicle Electrical System

With the increasing international oil crisis and the awareness of environmental protection,electric vehicles have received increasing attention from the international community.Due to electric vehicles have the characteristics of "zero pollution",they have become the key development direction of the automotive industry.Compared with traditional cars,electric vehicles are powered by power batteries.This feature determines the insulation requirements of electric vehicles.In order to ensure the safety of electric vehicles and the safety of the people on the vehicle,it has become more and more important to develop a system that can detect the insulation state of electric vehicles with high efficiency,accuracy,real-time and stability.The paper introduces the electrical system of electric vehicles firstly.After summarizing the advantages and disadvantages of several commonly used insulation detection methods,the low-frequency injection method with high detection accuracy and no influence on the detection object is adopted,and a formula for calculating the insulation resistance of a power battery is obtained.The hardware circuit and software design were then carried out.The hardware circuit of insulation detection is based on MC9S08DZ16 chip,which consists of MCU circuit,system power supply circuit,low frequency signal generation circuit,CAN communication circuit,insulation detection main circuit and signal processing circuit.The software design chooses C language as the programming language.The whole software program is written with structured design.Through the description and analysis of the main program and each subroutine flow chart,the whole process of the program and each sub-detail are explained in detail.Next,the multisim software simulation was performed on the hardware circuit of the insulation detection.Finally,the software program was downloaded to the MC9S08DZ16 chip of the hardware circuit and the experimental platform was set up for debugging.The data results obtained by simulation and debugging are given corresponding pictures,data tables and comparison descriptions,and the results are compared and analyzed in detail.Through simulation and experimental data analysis,it can be concluded that the insulation detection of the electrical system of the electric vehicle based on the low-frequency injection method is achievable,and the detection result of the insulation resistance is also accurate and reliable.