In traditional fuel vehicles, we can hear a variety of systems about safety and management, including ESP, ABS and other management systems that help drivers adjust the state and safety of the car, and also help drivers quickly adjust to a safe state when danger occurs.
And in the field of electric vehicles, the main source of electric vehicle power is the battery, at present, pure electric models use lithium-ion batteries, and lithium-ion batteries also have some of their own "small temper", in order to be able to make lithium-ion batteries can have a better working environment, state and mood, so, in the electric vehicle power battery, there is a special service for lithium batteries "battery management system", English name: Battery Management System, Referred to as BMS (bMS is summarized later), then, in order to make the most important lithium battery of electric vehicles have better working capacity, what is the use of BMS?
First of all, from the most familiar place, lithium batteries are still very sensitive to the ambient temperature, and the best working temperature is also relatively limited, lithium batteries are currently the most suitable working temperature between 10-30 degrees Celsius, high power is easy to cause battery heat, and low power, it will lead to battery life shrinkage and can not achieve the best work efficiency, so in the lithium battery is very "sensitive" situation, you have to have a "nanny" to help lithium batteries to control.
The main task of BMS is to keep the lithium battery in a normal and safe working state at all times, respond in time and deal with it quickly when the battery state is abnormal, and can help the battery adjust the charge and discharge power according to the vehicle driving state, ambient temperature, battery state, etc.
Battery management system includes a number of sensors, central control units, etc., in the BMS, the battery thermal management system is also the top priority, for this reason, the battery pack will also be set up independent cooling system and heating system, in order to be in the battery is in a non-normal working temperature, to help the battery return to the normal temperature state, to make the electric vehicle in the most efficient state of motion.
We all know that the power battery pack, not only a battery, but N multiple cells composition, whether it is Tesla's usual cylindrical battery, or bydi Ningde era square shell battery, etc., are composed of multiple cells of the power battery pack, and after a plurality of cells are connected to the power battery, each cell is also crucial, BMS is also responsible for the charge and discharge power of each cell, as well as the average of the entire power battery pack of the battery pack.
For example, in a class, there are N more than N students, and each student can not guarantee that the academic performance is exactly the same, it is inevitable to encounter which student is partial, individual students learn well, individual learning is poor, so it is necessary to need a teacher to tutor the students of the class, help each student to learn from each other, to adjust the balance of all students, to ensure the integrity of the class collective; and BMS is also responsible for the balance of all the cells in the power battery pack.
For the safety of the entire power battery pack, so when the battery is charged and discharged, in each stage, the voltage should also be adjusted in real time, such as when charging, the battery SOC is higher than 80%, which will reduce the charging speed, in order to give the battery better charging performance, and the BMS is the charging housekeeper; we also make an analogy, assuming that each battery cell is a bucket, and the charging is a large water pipe, when charging, it is random to put water into each bucket, and the water flow that is initially certain to be released is very large, and when all the buckets are almost full, the water flow should be reduced To ensure that each bucket can be filled with water evenly and smoothly as much as possible, so the speed of water flow should be adjusted according to the situation, and BMS also adjusts the charge and discharge voltage in a timely manner according to the charging state, not only to ensure the maximum efficiency of the battery, but also to ensure the safety of the battery as much as possible.
Therefore, although BMS sounds like a very small system, the importance of the electric vehicle power battery pack is very high, and it can control many driving factors such as safety and efficiency, so BMS is a very important part of lithium-ion batteries.
In the increasingly rapid development of new energy pure electric vehicles, each brand has its own battery layout and arrangement and the use of battery attributes are different, so in the BMS, will also do a unique BMS management development for different battery packs and cells, to ensure that each product and different battery packs can be in the best work efficiency, but also as far as possible to ensure battery safety, so the BMS system also determines many factors of electric vehicles.