What is the difference between energy storage battery BMS and power CR2032 button cell batteries

1. Application scenarios of large-scale energy storage systems

In order to achieve the purpose of smoothing output power fluctuations, more and more power plants are equipped with energy storage systems, such as new energy power stations, wind power stations or solar power stations.

Independent energy storage power stations, as the reform of the power system gradually enters people's field of vision, independent energy storage power stations that make a living by reselling electricity gradually appear.

Microgrid, a small power supply and distribution network that includes distributed power sources, power loads, energy storage systems and power grid management systems. In order to ensure the continuity and stability of power consumption of loads, each microgrid will be equipped with an energy storage system.

2. The difference between energy storage battery management system (ESBMS) and power battery management system (BMS)

Energy storage battery management system is very similar to power battery management system. However, the power battery system is in high-speed electric vehicles, and has higher requirements for battery power response speed and power characteristics, SOC estimation accuracy, and the number of state parameter calculations.

The scale of energy storage system is extremely large, and the centralized battery management system is significantly different from the energy storage battery management system. Here we only compare it with the distributed battery management system of power batteries.

2.1 The positions of batteries and their management systems in their respective systems are different

In the energy storage system, the energy storage battery interacts only with the energy storage converter at high voltage. The converter draws power from the AC power grid to charge the battery pack; or the battery pack supplies power to the converter, and the power is converted into AC by the converter and sent to the AC power grid.

For the communication of the energy storage system, the battery management system mainly has information interaction with the converter and the energy storage power station dispatching system. On the one hand, the battery management system sends important status information to the converter to determine the high-voltage power interaction; on the other hand, the battery management system sends the most comprehensive monitoring information to the PCS, the dispatching system of the energy storage power station.

The BMS of electric vehicles has energy exchange relationships with both the motor and the charger at high voltage; in terms of communication, it has information interaction with the charger during the charging process, and has the most detailed information interaction with the vehicle controller during the entire application process. As shown in the figure below.

2.2 Different hardware logical structures

For energy storage management systems, the hardware generally adopts a two-layer or three-layer model, and the larger scale tends to adopt a three-layer management system.

For the power battery management system, there is only one centralized layer or two distributed layers, and basically no three-layer situation occurs. Small cars mainly use a centralized battery management system. A two-layer distributed power battery management system is shown in the figure below.

From a functional point of view, the first and second layer modules of the energy storage battery management system are basically equivalent to the first layer acquisition module and the second layer main control module of the power battery. The third layer of the energy storage battery management system is an additional layer on this basis to cope with the huge scale of energy storage batteries.

Let's make a not-so-appropriate analogy. The best number of subordinates for a manager is 7 people. If the department continues to expand and 49 people appear, then 7 people have to choose a team leader and appoint a manager to manage these 7 team leaders. Beyond personal ability, management is prone to confusion.

Mapped to the energy storage battery management system, this management capability is the computing power of the chip and the complexity of the software program.

2.3 There are differences in communication protocols

The energy storage battery management system basically uses the CAN protocol for internal communication, but its external communication, mainly the energy storage power station dispatching system PCS, often uses the Internet protocol format TCP/IP protocol.

Power batteries and electric vehicles all use the CAN protocol, but the internal CAN is used between the components inside the battery pack, and the whole vehicle CAN is used between the battery pack and the whole vehicle.

2.4 The parameters of the management system are quite different if the types of cells used in the energy storage power station are different

For safety and economic considerations, energy storage power stations often choose lithium iron phosphate when selecting lithium batteries, and some energy storage power stations use lead-acid batteries and lead-carbon batteries. The current mainstream battery types of electric vehicles are lithium iron phosphate batteries and ternary lithium batteries.

Different battery types have huge differences in external characteristics, and battery models are completely incompatible. The battery management system and cell parameters must be one-to-one. The detailed parameter settings of the same type of cells produced by different manufacturers will not be the same.

2.5 Different threshold setting tendencies

Energy storage power stations have more space and can accommodate more batteries, but some power stations are located in remote areas and transportation is inconvenient, and large-scale replacement of batteries is a relatively difficult task. Energy storage power stations expect the cells to have a long life and not to fail. Based on this, the upper limit of its working current will be set relatively low to prevent the cells from working at full load. The requirements for the energy and power characteristics of the battery cells do not need to be particularly high. The main consideration is the cost-effectiveness.

Power batteries are different. In the limited space of the vehicle, the battery is finally installed and it is hoped that its capacity will be maximized. Therefore, the system parameters will refer to the battery's limit parameters, and such application conditions are bad for the battery.

2.6 The number of state parameters required to be calculated by the two is different

SOC is a state parameter that needs to be calculated by both. But until today, there is no unified requirement for energy storage systems, which state parameter calculation capabilities must be required for energy storage battery management systems. In addition, the application environment of energy storage batteries has relatively abundant space and a stable environment, and small deviations are not easily perceived in large systems. Therefore, the computing power requirements of energy storage battery management systems are relatively lower than those of power battery management systems, and the corresponding single-string battery management costs are not as high as those of power batteries.

2.7 Passive balancing conditions for energy storage battery management systems are relatively good

Energy storage power stations have urgent requirements for the balancing capabilities of the management system. The scale of energy storage battery modules is relatively large, and multiple strings of batteries are connected in series. The larger single-cell voltage difference will cause the capacity of the entire box to decrease. The more batteries are connected in series, the more capacity is lost. From the perspective of economic efficiency, energy storage power stations need sufficient balancing.

In addition, passive balancing can be more effective in ample space and good heat dissipation conditions. With a relatively large balancing current, there is no need to worry about excessive temperature rise. Low-cost passive balancing can be used in energy storage power stations.

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