Study On Battery Management System Of Environment-friendly Electric Vehicle

With the improvement of people’s environmental awareness and concerns about the energy crisis, new energy vehicles gradually get people’s attention. Electric vehicles(EVs) emerge as the best one from new energy vehicles by its features. EVs are powered by a battery pack that consists of cells in series, and individual differences between cells can cause over-charge and over-discharge in the process of charging and discharging, which would seriously damage the battery life; Drivers also need to know the health of cells and energy usage. Therefore, the battery management system came into being.A master-slave battery management syste m was designed and implemented to meet the actual demand of an enterprise, and cells energy was used to estimate the its SOC and SOH. Using LTC6803 chip for the voltage and temperature acquisition improve the accuracy of data collection. An adjustable constant current source was designed which can offer a large current to improve the efficiency of balance and the consistency of the battery pack. A balanced circuit topology was designed which is based on MOS transistors and high current protection diodes to ensure balance flexibility and security. Finally battery management system was developed based on UCOS-II embedded system to manage various functional modules and achieve the charge and discharge control, fault detection, data storage, SOC and SOH calculations.The performance of each module was verified successfully before a road test. The results show that the BMS data collections, such as voltage, temperature, charge and discharge current collection, are accurate, and its balance is efficient, and SOC and SOH estimating are reliable.