The Research On Power Li-ion Battery Management System

The development of automobile brought great convenience to human, but also brought harm to the environment we live. Meanwhile, the fuel consumption of traditional automobile is a non-renewable energy. With the increase of people’s awareness of environmental protection and intensifies of energy crisis, new energy vehicles get more and more attention due to its advantages. The new energy vehicles have risen to the level of national strategy in many countries. In our country, the state has adopted series of policies to encourage and support the development of new energy vehicles. New energy vehicles include hybrid electric vehicles, pure electric vehicles and fuel cell vehicles. In a few years ago, due to limitations of battery technology, the development of new energy vehicles is not smoothly. In recent years, with the maturing of lithium battery technology, new energy vehicles got a "blowout" type of development. Lithium battery with high performance, low-pollution or non-pollution got more and more attention of the automobile industry, and was known as the most potential energy carries of new energy vehicles. The management of lithium ion battery has become one of the hot spot field.This battery management system(BMS) for 74 series power lithium battery packs adopted distributed architecture based on CAN bus, consist of battery pack module and main control unit. The battery pack modules exchange data with main control unit through the CAN bus. The charger, voltage balance and discharger of Battery packs centralized controlled by the main control unit. This architecture can increase or decrease the number of cells with conveniently.In this paper, this system is introduced from four aspects:the acquisition of external parameters of battery packs, battery management system architecture and core hardware design, battery management system SOC measure and control strategy, the battery management system software design.The single voltage measure for battery packs was been researched in this paper. Put forward a kind of low cost, high precision single voltage measure methods for battery packs. This method features low cost, simple, reliable, smaller effect for battery, high precision and error of less than 0.1% at room temperature.The method of SOC measure, control strategy was been researched. The fault manage, state manage, control strategy of charge and discharge, thermal management of battery packs was detailed in this paper. Enhanced the battery packs safety and increased battery packs cycle number.The battery management system software was been researched. The software structure of multi-node parallel processing program is been adopted in software design. It features simple, good real-time performance and stability.Finally, the deficiencies of battery management system and improvement program are descried.