Battery Management System Design And State Of Charge Estimation Based On Ampere-Hour Method

From the perspective of energy conservation and environmental protection, bothHEV and PHEV are transitional products. On long term development, pure electricvehicle, the ideal green energy product, is the inevitable trend of future development.Because of the advantages of high energy density and stable performance comparedwith other batteries, lithium-ion battery will be the main power source of electricvehicle in the future. There are several factors restricting the development of electricvehicle, including cost, stability and security of the battery, Battery ManagementSystem (BMS) is a link between battery and the vehicle controller. As the electroniccomponent realizing real-time monitoring, automatic balancing and intelligentcharging and discharging of battery, BMS is an indispensable component of the powerand energy storage battery pack. It plays an important role in ensuring battery safety,prolonging battery life and estimating remaining capacity of the battery pack. In thisarticle, a complete BMS is designed for the series lithium iron phosphate battery pack.Firstly, the performance of lithium iron phosphate battery pack is studied. Andthe detection flowcharts of battery voltage, current and temperature are designedbased on the above work. Then the battery pack equalization algorithm, SOCestimation method and safety management scheme are designed. Finally, the CANcommunication protocol is designed to realize the communication of the systembecause of the distributed control scheme of the system. And a monitoring program isadded to the software implementation process to ensure system reliability.Experimental results show that the designed BMS realized the monitoring andmanagement of battery pack reliably, and accurately estimated the remaining capacityof the battery pack.And the stability and security of the system are verified.