What are the differences between the energy storage battery BMS system and the power battery BMS system?

The BMS battery management system is an indispensable component of power and energy storage battery pack, which plays important functions such as ensuring safety, extending the service life, and estimating the remaining power, to a certain extent, it improves the battery life and reduce the loss caused by battery damage.

The energy storage battery management system is very similar to the power battery management system. Most people do not know the difference between the power battery BMS management system and the energy storage battery BMS management system. We will briefly introduce the differences between these two BMS management systems.

1. The battery and its management system have different positions in their respective systems

In the energy storage system, the energy storage battery only interacts with the high-voltage energy storage converter, the converter takes power from the AC grid, charges the battery pack, or the battery pack supplies power to the converter, and the electrical energy is converted to AC through the converter.

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

The electric vehicle BMS has an energy exchange relationship with the motor and the charger under high voltage, and has information interaction with the charger during the charging process, and has the most detailed information interaction with the vehicle controller in all application processes.

2. The logical structure of the hardware is different

For the energy storage management system, the hardware generally adopts a two-layer or three-layer mode, and the larger scale tends to be a three-layer management system. The power battery management system has only one layer of centralized or two distributed layers, and almost no three layers. Small cars mainly use centralized battery management systems, two-layer distributed power battery management system.

From a functional point of view, the first layer 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 added layer to deal with the huge scale of energy storage batteries. Mapped to the energy storage battery management system, the management capability is the computing power of the chip and the complexity of the software program.

3. Communication protocols are different

The energy storage battery management system and internal communication basically use the CAN protocol, but the external communication mainly refers to the energy storage power station dispatching system PCS, which mostly adopts the TCP/IP protocol in the form of Internet protocol.

The main space of power batteries and electric vehicles adopts the CAN protocol, but the internal CAN is used between the internal components of the battery pack, and the vehicle CAN is used to distinguish between the battery pack and the whole vehicle.

4. The core types used in the energy storage power station are different, and the parameters of the management system are quite different.

Considering the safety and economy of energy storage power stations, when choosing lithium batteries, lithium ion phosphate is mostly selected, and more energy storage power stations use lead batteries and lead carbon batteries. The current mainstream battery types for electric vehicles are lithium ion phosphate batteries and ternary lithium batteries.

Different battery types have very different external characteristics, and battery models are not universal at all. The battery management system and core parameters must be in one-to-one correspondence. The same type of cores produced by different manufacturers have different setting of detailed parameters.

5. Threshold setting trends are different

Energy storage power stations have abundant space and can accommodate more batteries, but some power stations are located in remote locations and are inconvenient to transport, making it difficult to replace batteries on a large scale. The expectation of the energy storage power station for the cells is that they have a long life and do not fail. On this basis, the upper limit of its working current is set relatively low to avoid electrical load work. The energy characteristics and power characteristics of the cells do not have to be particularly high, mainly depends on the price.

Power battery is different, it is not easy to install the battery in the limited space of the vehicle, and it is hoped to maximize its capacity. Therefore, the system parameters refer to the limit parameters of the battery, and this application condition is not good for the battery.

6. The two state parameters required to be calculated are different

SOC is a state parameter that both need to be calculated. However, up to now, there is no unified requirement for the energy storage system. What state parameter calculation capability does the energy storage battery management system need? In addition, the application environment of energy storage batteries is rich in space and stable in the environment, and small deviations are difficult to perceive in large systems. Therefore, the computing power requirement of the energy storage battery management system is relatively lower than that of the power battery management system, and the corresponding single-string battery management cost is not as high as that of the power battery.

7. Energy storage battery management system, the application of passive balance conditions is good

The energy storage power station has very urgent requirements for the balancing ability of the management system. The scale of the energy storage battery module is relatively large. Multiple batteries are connected in series, and a large single voltage difference will reduce the capacity of the entire box. The more batteries connected in series, the more capacity will be lost. From the point of view of economic efficiency, the energy storage power station needs to be fully balanced.

In addition, under abundant space and good heat dissipation conditions, passive balancing can be more effective, so a larger balancing current is used, and there is no need to worry about the temperature rising too high. Low-cost passive balance can be used in energy storage power stations.