Research Of Insulation Monitoring System Of Electric Vehicle(EV) Power Battery Pack Based On Bridge Method

Throughout the world,energy and environmental issues have become increasingly severe.Countries around the world are vigorously promoting new energy vehicles featuring energy conservation and environmental protection,among which electric vehicles are at the top of them.For pure electric vehicles,the power battery is the only power source in the car.Now the voltage of ordinary passenger cars is generally more than 300 V.For pure electric coach,it is even more than 600 V.With the increase of voltage platform,the Real-time monitoring of the insulation performance of highvoltage systems becomes more and more important.This article is based on the new energy vehicle collaborative innovation comprehensive service platform(2016XK2008),Innovation and development of China Power Valley in Zhuzhou(ZJ/2016-006)and other topics,and also,it is based on the 10.5m pure electric passenger car project of Changsha Meihua Automobile Co.,Ltd.,The electric vehicle battery pack insulation monitoring system was studied.The main work and innovation of this article are as follows:(1)Several kinds of commonly used insulation resistance detection methods were deeply studied and analyzed.The insulation resistance detection method for balancedunbalanced bridges was proposed.The insulation simulation model of the whole vehicle was built using Multisim to make feasible analysis of the insulation resistance detection method of balanced-unbalanced bridge.(2)The insulation monitoring system adopts a modular design concept and uses the 8-bit microcontroller MC9S08DZ60 of Freescale as the main control unit of the system to complete the modular hardware design and program design of the monitoring system,and to calculate and monitor the insulation resistance of the insulation monitoring system,the total voltage of the battery pack,and the current of battery charge and discharge.(3)According to the harsh electromagnetic environment of electric vehicles,in order to improve the electromagnetic immunity and electrical load capacity of the insulation monitoring system,isolation design is adopted in the hardware architecture design,and validity judgment and filtering algorithms of major signals are added to the software architecture design.Analysis of the measured data shows that the system’s electromagnetic immunity and electrical load capacity meet the design requirements.(4)Through the simulation test platform,electric logistics vehicle road test platform and the actual installation and debugging of the electric coach,the three performance tests of the insulation monitoring system were completed.And the insulation monitoring system also completes various tests developed by the Chongqing Vehicle Inspection Center for new energy vehicles.Various indicators of the system meet the product requirements.