Battery Management System, used for real-time monitoring of battery parameters, fault diagnosis, SOC estimation, mileage estimation, short circuit protection, leakage monitoring, display alarm, charging and discharging mode selection, etc.

Since the cell is an electrochemical process, multiple cells form a battery, and each cell has its own characteristics. No matter how precise the manufacturing, depending on the time and environment of use, there will be errors and inconsistencies in each cell. Therefore, the battery management system evaluates the current battery status through limited parameters.

In terms of usage, BMS is roughly divided into two categories, one is for new energy vehicles, and the other is for energy storage. This article will mainly introduce the usefulness of BMS when applied to new energy vehicles.

Real-time tracking of battery operating status and parameter detection: real-time collection of battery charging and discharging status, collected data include total battery voltage, total battery current, temperature of battery measurement points in each battery box, and battery voltage of single modules. Since power batteries are used in series, real-time, fast and accurate measurement of these parameters is the basis for the normal operation of the battery management system.

Estimation function: BMS estimation function has four major aspects, one is SOC (State Of Charge), which belongs to the core control algorithm of BMS, which characterizes the current state of remaining capacity; the other is SOP (State Of Power), which is mainly through temperature and SOC look-up table Get the available charge and discharge power of the current battery, the VCU decides how to use the current vehicle according to the power value sent; the third is SOH (State Of Health), which mainly represents the current battery health status, which is a value between 0-100%, which is generally considered The battery can no longer be used when it is lower than 80%; the fourth is SOE (State Of Energy), this function is mainly used to estimate the remaining cruising range. At present, domestic manufacturers of this algorithm have not developed much, or adopt a relatively simple algorithm, and look up the table to get the ratio of the remaining energy to the maximum available energy in the current state.

Charge and discharge control: control the charge and discharge of the battery according to the state of charge of the battery. When a certain parameter exceeds the standard, such as the voltage of the single battery is too high or too low, to ensure the normal use and performance of the battery pack, the system will cut off the relay , Stop the battery's energy supply and release.

Fault diagnosis: According to the different performance of the battery, it is divided into different fault levels. In the case of different fault levels, the BMS and VCU will take different treatment measures, warning, limiting power or directly cutting off the high voltage. Failures include data collection and rationality failures, electrical failures (sensors and actuators), communication failures, and battery status failures.

Thermal management: real-time collection of the battery temperature in each battery box, and control of the cooling fan to prevent the battery temperature from becoming too high.

Equalization control: Equalization function is to eliminate the inconsistency of battery cells during battery use. According to the short-board effect of the barrel, both the worst-performing monomers during charging and discharging will reach the cut-off condition first. A part of the capacity has not been released, causing battery waste.