BMS (BATTERY MANAGEMENT SYSTEM), commonly known as battery nanny or battery housekeeper, is mainly to intelligently manage and maintain each battery unit, prevent the battery from overcharging and overdischarging, extend the life of the battery, and monitor the status of the battery.
Core functions of BMS
1) Cell monitoring technology
1, single battery voltage acquisition;
2, single battery temperature collection;
3, battery current detection;
The accurate measurement of temperature is also very important for the working state of the battery pack, including the temperature measurement of a single battery and the temperature monitoring of the battery pack cooling liquid. This requires a reasonable setting of the position and number of temperature sensors 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 fluid temperature of the inlet and outlet, and the monitoring accuracy is similar to that of a single battery.
2) SOC (State of Charge) technology: Simply put, how much power is left in the battery
SOC is the most important parameter in BMS, because everything else is based on SOC, so its accuracy and robustness (also known as error correction) are extremely important. Without a precise SOC, no amount of protection can make the BMS work properly, because the battery will often be in a protected state, and it will not be able to extend the battery life.
The higher the accuracy of the SOC, the higher the range of the electric vehicle for the same capacity of the battery. High precision SOC estimation enables maximum battery pack performance.
3) Equalization techniques
Passive equalization generally uses resistance heat release to release the "excess electricity" of high-capacity batteries, so as to achieve the purpose of equalization, the circuit is simple and reliable, the cost is low, but the battery efficiency is also low.
The excess power is transferred to the high-capacity cell during active balanced charging, and the excess power is transferred to the low-capacity cell during discharge, which can improve the use efficiency, but the cost is higher, the circuit is complex, and the reliability is low. In the future, as the consistency of the cell increases, the need for passive equilibrium may decrease.
