The BMS electric vehicle battery management system is an important link to connect vehicle power batteries and electric vehicles.

　　The important information of the BMS in real -time collection, processing, and storage battery packs, exchange information with external devices such as vehicle controller, and solve key issues such as safety, availability, ease of use, and service life in the lithium battery system.

　　The main role is to improve the utilization rate of batteries, prevent excessive charging and excessive discharge of batteries, and extend the service life of the battery.

　　Monitor the status of the battery. In popular terms, it is a system of management, control, and battery pack.

　　The three most core functions of BMS are battery cell monitoring, load power status (SOC) estimation, and single battery equilibrium.

　　1. Core monitoring technology

　　1. Collecting of single battery voltage; 2. Merodic battery temperature collection; 3. Battery box 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 battery pack heat dissipation liquid. This requires a reasonable setting of the location and the number of uses of the temperature sensor, and forms a good cooperation with the BMS control module.

　　The monitoring of the temperature of the battery set heat dissipation liquid focuses on the fluid temperature of the entrance and export. The choice of monitoring accuracy is similar to that of a single battery.

　　2, SOC technology

　　Single -core SOC calculation is the focus and difficulty of BMS. SOC is the most important parameter in BMS, because everything else is SOC as the

　　The foundation, so its accuracy and robustness (also called error correction ability) are extremely important. If there is no precise SOC, no more protection function can make BMS work normally, because the battery will often be protected, and the life of the battery cannot be extended. The higher the accuracy of the SOC estimation, the higher the battery of the same capacity, which can make electric vehicles a higher range of mileage. High -precision SOC estimates can make the battery pack maximum efficiency.

　　At present, the most commonly adopted calculation methods include the peaceful integration method and the opening voltage calibration method. By establishing a battery model and a large amount of data collection, the actual data is compared with the calculation data. This is also the technical secrets of each family. Accumulation, also the highest technical content in Tesla. Tesla has applied for more than hundreds of core patents related to BMS in the fields of battery cooling, safety, charge balance.

　　3, equilibrium technology

　　Passive equilibrium generally uses resistance heat to release the "extra power" of high -capacity batteries, thereby achieving a balanced purpose. The circuit is simple and reliable, the cost is low, but the battery efficiency is also low.

　　During the active equilibrium charging, the excess electricity volume is transferred to a high -capacity battery cell. When discharging, the excess electricity volume is transferred to a low -capacity battery cell, which can improve the efficiency of usage, but the cost is higher, the circuit is complicated, and the reliability is low. In the future, as the consistency of the cells increases, the demand for passive balance may decrease.

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