The Study And Plan On The Battery Management System Applied For EV Based On MC9S12DP512 And CAN Bus

Energy-saving and environmental protections have been targeted on the development of the automobile industry. As a new type of transport adding a source of energy diversification,the new generation of electric vehicles arouse widespread concern and have been greatly developed with its benefits of zero emission and low noise.However,battery and its application technology still restrict the development of electric vehicles.Electric vehicle energy management system necessarrily solves problems on how to prolong battery life span and on how to improve energy efficiency and reliability of the battery.Battery Management System is one of the key technologies strengthening practical and commercial utilization of electric vehicles.As an integral part of the energy management system, forecast for state of charge of the battery played an important role in commercialization of electric vehicles.Therefore the research of Battery Management Technology and System was of great significance.Battery management system directly controls and manages the whole process of running battery, including charging and discharging process, the safety protection, estimation of state of charge, the balancing between batteries, fault diagnosis and so on.On the basis of research of foreign advanced battery management system, significant improvements are made on the design of configuration and circuit, such as the introduction of CAN bus, the new SOC estimation method, advanced data processing technology in view of battery inconsistency and fault diagnosis expert systems.As to nickel hydrogen battery ,we discussed chemical thermodynamic principle in detail, established an accurate and reliable mathematical model for battery management system and reasonably simulated changes in battery voltage, current, power, temperature, efficiency and SOC.We also simulated cooling fan control,a degree of fault diagnosis and fault alarm functions. Changes can be easily made on the basic parameters of the model, such as environmental temperature, rated capacity and the number of monomers according to the different needs of users.BMS design process obeyed the modularity principle.As to hardware circuit design we used the 16-bit embedded microcontroller MC9S12DP512 of freescale company as a core control unit and expanded the associated external circuit with its related modules.Thus implementation were made on precise detection of battery performance parameters, including the module voltage, the pack voltage, current, temperature, run-time, dynamic battery status (power-on, warning, error, danger,etc.), the maximum allowable charging current and the maximum allowable discharge current.As to software algorithm we established the compound surplus capacity forecasting method combining methods of the Ah-time, open-circuit voltage and Kalman filtering law.The designed BMS can timely and reliably respond to battery unusual circumstances with its function of rich and comprehensive fault diagnosis.The BMS also featured with thermal management control, stability anti-jamming capability, multi-function surveillance interface as well as function of quick CAN communication for electric vehicle.A large number of experimental data proved the feasibility and effectiveness of the designed BMS.The paper work was an significant part of the research project—Geely Automobile new electric vehicle technology research and development,which was successful through the staged check of the National Science and Technology in January 2008.