Battery Management System

2021-04-17 15:24


The FOXWER brand charger uses a battery management system. Monitor the current, voltage, temperature, residual capacity, etc.。Battery Management System is a system for battery management. BMS is mainly for the intelligent management and maintenance of each battery unit, prevents overcharge and overdischarge of the battery, prolongs the service life of the battery, and monitors the status of the battery.

BMS is an electric vehicle battery management system and an important link between the vehicle power battery and the electric vehicle. BMS collects, processes, and stores important information during the operation of the battery pack in real time, exchanges information with external devices such as vehicle controllers, and solves key issues such as safety, availability, ease of use, and service life in the lithium battery system.

The main function is to improve the utilization rate of the battery, prevent the battery from being overcharged and over-discharged, extend the service life of the battery, and monitor the state of the battery. In layman's terms, it is a system for managing, controlling, and using battery packs.

Extended information:

1. Cell monitoring.

The main functions of the battery cell monitoring technology include single battery voltage collection; single battery temperature collection; battery pack current detection. The accurate measurement of temperature is also very important for the working status of the battery pack, including the temperature measurement of a single battery and the temperature monitoring of the cooling liquid of the battery pack.

This requires a reasonable setting of the location and number of temperature sensors to be used in order to form a good cooperation with the BMS control module. The monitoring of the temperature of the cooling liquid of the battery pack focuses on the temperature of the fluid at the inlet and the outlet, and the selection of monitoring accuracy is similar to that of a single battery.

2. SOC technology
Single-cell SOC calculation is the key and difficult point in BMS. SOC is the most important parameter in BMS. Because everything else is based on SOC, its accuracy and robustness (also called error correction capability) are extremely important .
If there is no accurate SOC, no amount of protection functions can make the BMS work normally, because the battery will often be in a protected state, and it will not be able to extend the life of the battery. The higher the accuracy of the estimation accuracy of SOC, the higher the cruising range of the electric vehicle for the battery of the same capacity. High-precision SOC estimation can maximize the efficiency of the battery pack.
At present, the most commonly used calculation methods are the ampere-hour integration method and the open circuit voltage calibration method. Through the establishment of a battery model and a large amount of data collection, the actual data is compared with the calculated data. This is also the technical secret of each company, which requires a large amount of data for a long time. Accumulation is also the part with the highest technical content of Tesla.

3. Balance technology
Passive equalization generally uses resistance to release the "excess power" of high-capacity batteries, so as to achieve the purpose of equalization. The circuit is simple and reliable, and the cost is low, but the battery efficiency is also low.
Transferring excess power to high-capacity cells during active equalization charging and transferring excess power to low-capacity cells during discharging can improve use efficiency, but the cost is higher, the circuit is complex, and the reliability is low. In the future, with the improvement of battery cell consistency, the demand for passive balance may decrease.