Design Of Electric Vehicle Lithium Battery Management System

Because the problems of energy shortage and environment pollution are getting more and more severe, the research of electric vehicles has become the tropical issues around the world for it's virtue of green initiative. For the advantages of excellent performance, small size, light weight and lower environment pollution, lithium-ion batteries has become the ideal choice of power batteries for electric vehicles. But the safety performance is one of the main factors constraining the development of lithium-ion. How to ensure the safety performance of the battery pack and prolong the battery life has been the main research area.According to the characteristics of lithium-ion battery, this paper present a battery management system based on CAN bus. This system uses the building block structure and is consist of main control unit and monitoring and controlling units. The main control unit uses the MC9S12DG128 MCU as main controller, the monitoring and controlling units use MC9S08DZ16 as main controller. The main control unit and the monitoring and controlling units are connected by CAN bus.Despite the management system discussed in this paper, the remaining capacity estimation algorithm of lithium batteries is also studied in details. The modeling analysis is carried on according to the properties of Lithium iron phosphate battery. Considering the efficiency of charge and discharge compensation, a kind of SOC estimation that combines of amp integration and open-circuit voltage is proposed in this paper.The battery management system designed in this paper can be used to monitor and manage the real-time status of lithium-ion battery.The system has the advantages of simple structure,high reliability,extensible, and easy maintenance.