Design of microcontroller-based battery management system for pure electric vehicle

Energy conservation and environmental protection have become new targets of the development of the automobile industry. A new generation of electric vehicles have gotten a great development, which can diversify transport configuration with its zero-emission, low noise, etc., and attract extensive attentions worldwide. However, the battery problem of energy storage and application technology remains to restrict the development of electric vehicles. How to extend battery life and improve battery energy efficiency and operational reliability are problems that must be addressed for the electric vehicle energy management system. Battery management system is one of the key technologies related to electric vehicles and plays an important role in practice and commercialization, so the technology research of battery management system has a great significance. In all secondary batteries, the lithium batteries have the highest energy density and power density ratio, and became the most widely used electric vehicle batteries. Because of the inherent characteristics of lithium battery materials, overcharge, over-discharge, and over-temperature, battery pack performance will rapidly decay and eventually cause the battery pack failure. Therefore, the battery management system for lithium batteries plays an important role in extending the battery life cycle and maintaining safe operation of electric vehicles. This paper presents a kind of battery management system with a Freescale microcontroller core. It can provide accurate measurement of the battery cell voltage, total battery voltage, battery temperature, ambient temperature, current, and other information. The battery management system can also provide data to support the analysis of battery performance. In addition, the hardware circuit of the system has the functions of battery over-voltage/under-voltage protection and energy balance, etc., and the single cell can be monitored and implement the necessary protection. A PC monitoring system obtains data related to the battery via the CAN bus communication from the battery management system, and achieves the battery status real-time display, while all the data can be saved to a file. The PC monitor interface can achieve programming control of the working status of charging and discharging battery pack and is able to set the parameters of the battery failure, to ensure the security of the battery charging and discharging process. The experiments verified the physical parameters of the system on battery power detection with high accuracy and achieved a dynamic two-way balancing. In addition, the battery management system functions are verified on CAN communication and the voltage display. At last, a balanced experimental verification of effectiveness equalization was conducted. The equalization was divided into two functional verifications, one was the microscopic detection of the presence and size of the equilibrium current, the other was whether the macro cell voltage converged to the average voltage. The results showed that the battery management system could meet the requirements on measuring accuracy, reliability, and effectiveness equalization. The battery-powered, battery testing, and performance analysis applied technology research provides a reliable platform and data support.