An overview and classification of battery management systems.

     Compared with lead-acid batteries, the performance characteristics of lithium batteries determine that they cannot be overcharged, over-discharged, over-temperature, over-current, short-circuit and other characteristics. Therefore, in order to ensure the high safety and long-life operation of the lithium battery, and to ensure the high safety and long-life operation of the battery, electronic (and) electrical components are used to design the circuit to monitor the voltage, temperature, current, and insulation status of the battery in real time, and dynamically estimate the SOC , Perform overcharge, overdischarge, over temperature, over current, leakage protection, balance, communicate with peripherals to achieve system coordination control, etc., which are the basic functions of the battery management system.

     There are two main categories of classification. One is a relatively low-end battery protection board, and the other is a battery management system. In the early days, the battery protection board was mainly based on hardware. Now it is gradually becoming intelligent, putting forward some requirements for communication and monitoring, and gradually extending the software battery protection board. The battery management system is mainly divided into two-level architecture management system and three-level architecture management system.

Classification of battery management systems

1. Hardware protection board

The hardware protection board is suitable for systems with lithium batteries ranging from 1 string to 32 strings within 100V. Usually have voltage and current protection functions, and some high-end chips have temperature protection, disconnection protection and other protection equalization functions. The main application areas include mobile phones, vacuum cleaners, electric toothbrushes, street lights, electric tools, electric bicycles, and motorhome power supplies.

2. Software protection board

The minimum number of strings for the software protection board is 2 strings. We are now cooperating with international large-scale intelligent robots. 2 strings can achieve a software board with communication and estimation. The high one is mainly 32 strings, with temperature, voltage, current acquisition functions and SOC estimation functions, and can also be balanced according to strategies to achieve external communication. The main application areas are backup power for base stations, home energy storage, robots, AGVs, high-end electric bicycles, electric motorcycles, and battery packs for battery replacement. For example, the lithium-ionization of electric bicycles was applied in 2010. At that time, it was mainly based on ternary. Generally, low-end hardware boards are used.

    The main difference between the protection board and the BMS is that all the protection actions of the protection board are carried out on this board. It does not cooperate with the external electrical and mechanical parts. The whole is realized by semiconductors to achieve basic protection actions, so it is called the protection board. .

3. BMS battery management system

The battery management system is relatively complicated. The early stage has a two-level architecture. The two-level architecture is generally a master control, which combines a series of slave controls. The general voltage range is within 1500V between the master control and the slave control, within 5 years Due to cost challenges, it is mainly used in passenger cars, commercial vehicles, etc. Energy storage is generally an energy storage system with a scale of tens of KWh to 100 KWh. The three-level architecture of BMS includes slave control and master control. The slave control and the master control constitute the management of the battery. Then the energy storage system above the megawatt level needs to have another layer of cluster management to form a three-layer management structure. Comprehensive management of PAS remote monitoring system and other interactions.