no 5 alkaline battery.A brief introduction to the electric vehicle BMS system: the "staff officer" and "general" of the battery cell

　　The three electric technologies in electric vehicles: battery, motor, and electronic control technology are the core technologies of electric vehicles. Because the use of these three technologies is required by every electric vehicle and directly affects the vehicle's cruising range, acceleration time and other parameters. These three technologies are the wooden barrels that make up electric vehicles. If any one of them has shortcomings, it will directly affect the performance of the vehicle.

　　Among the three electric technologies, the impact of batteries and motors on the performance of electric vehicles is relatively obvious. For example, the power of the motor directly affects the power performance of the vehicle, and the energy storage of the pure electric vehicle battery is closely related to the vehicle's cruising range. But what is the specific technical application of the electronic control technology in the three-electric system in electric vehicles? Why can it be considered together with batteries and motors and occupy a place in the three-electric system?

　　The core function of electronic control is the battery management system (Battery management system) referred to as BMS. Without this system, the charging, discharging, and service life of the power battery will be greatly reduced. If the battery is compared to a group of soldiers participating in the war, then the BMS system will be the staff and general of this group of soldiers, allowing electric vehicles to achieve twice the result with half the effort in practical applications. Effect.

　　Why have a BMS system?

　　If you want to fully understand this "general" on electric vehicles, you must first start with the soldiers below. The BMS system is mainly used in secondary batteries, especially for the current mainstream electric new energy vehicles using lithium-ion batteries. Regardless of the vehicle Which kind of lithium-ion battery is used? The power battery is composed of small battery cells connected in series and parallel to form a battery pack, and then the battery pack finally forms the power battery unit of the vehicle.

　　What really plays the role of energy storage in the battery pack is each small battery cell in the battery pack. For example, the 18650 lithium-ion battery used by Tesla. In fact, the number represents that each battery cell has a diameter of 18mm and a length of is 65mm. And an 85kW one? The battery pack of the h version of Tesla Model S is composed of nearly 7,000 18650 lithium batteries.

　　There are so many battery cells in a car, and each small battery cell is manufactured separately. Due to the electrochemical characteristics of the battery, the energy storage consistency of each cell after leaving the factory is different. question. When charging, the car is charged from a charging port. How to ensure that each battery is fully charged without causing damage to the battery due to overcharging is one of the problems that the BMS system needs to solve.

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