The concept of battery management system
The battery management system is the core of electric vehicle energy control. IEC and QC/T 897-2011 have formulated relevant standard functional requirements for BMS. The IEC formulates BMS function standards including: battery data collection, SOC estimation, battery cycle life, and alarm protection. The QC/T 897-2011 standard for BMS functions includes: battery cell voltage collection, battery temperature collection, remaining power estimation, safety warning and control, information processing, and information interaction. Based on the above standards and actual vehicle requirements, the basic functions that electric vehicle BMS must have: balance management function, thermal management function, CMU communication function, SOC estimation, life estimation, battery information monitoring, charging and discharging process control, data display and backup.
1) Battery information acquisition: The sensor on the acquisition board collects the charge and discharge status of the battery pack's current, working voltage data, and ambient temperature information, and feeds back to the main control chip through the CAN line;
2) Estimation of remaining power SOC: The collected battery data is provided to the main control chip, which estimates the remaining power SOC of the power battery pack according to the algorithm, and provides a reference for driving range;
3) Battery safety protection: safety management is responsible for monitoring the abnormality of the battery during the working process. In case of abnormality, the system should be able to deal with it immediately to ensure the normal operation of the battery pack and prevent combustion and explosion;
4) Electrical control management: During the charging and discharging process of electric vehicles, the power battery has the possibility of overcharging, overdischarging, and power imbalance between batteries, which will affect the service life and working efficiency of the battery. If it happens, the battery management system needs to react quickly and execute the predetermined measures effectively. For example, by cutting off the charging and discharging circuit to ensure the normal use and safe use of the battery pack;
5) Data communication display: firstly, the collected battery information is submitted to the BMS main control chip to process its power estimation and balance control, and then the results are sent to other devices for use through the CAN bus.
