The difference between energy storage BMS and electric vehicle BMS?

2021-10-22 08:35:30 0

The battery management system BMS is the core component of the energy storage system and has three functions:

1. Perception

First sense the status of the battery. How to manage the battery if you don’t even know the status of the battery? This state includes several: voltage, current, and temperature. Needless to say, this is the most basic quantity. The most important thing is to calculate the state of the battery SOX, including SOC, SOE, SOP, SOH, SOS. Everyone knows the first few, so what is SOS? SOS is the safe state of the battery.

2. Management

How to manage the battery? It is nothing more than two functions, balance management, passive balance, active balance, and thermal management, which are more realized in system design.

3. Protection

Take protection when there is an abnormal situation in the battery system, such as tripping or stopping charging or parking.

Compared with electric vehicles, energy storage systems have many peculiarities, so energy storage BMSs are very different from vehicle BMSs.

The energy storage system has a large number of batteries, the system is very complex, and the operating environment is very harsh. In such a very complex system, very high requirements are placed on the anti-interference performance of the BMS. Once the BMS in the energy storage system is interfered, such as data jumps, malfunctions, etc., it is caused by the insufficient anti-interference ability of the BMS. of. Similarly, the complexity of the system puts high demands on the BMS data processing capability and response speed.

The battery system will attenuate during use, and this attenuation mainly depends on two factors: the attenuation of the single cell itself due to recycling, and in the energy storage system, the discrete nature of the battery causes the attenuation of the entire battery. Obviously, the attenuation of the capacity of a single battery cannot be controlled, which is an inherent characteristic of the battery, but the attenuation of the entire group of batteries caused by the discreteness can be improved by controlling the consistency of the battery pack. Equalization is used to improve the consistency of the battery pack. Now many people are talking about active or passive equilibrium. I'll introduce it later.

The thermal management of BMS will not be expanded here.

There are many battery packs in the energy storage system, and there is balance management and circulation management between the groups, which is unique to energy storage BMS.

The access of a large amount of data requires the energy storage BMS control unit to have complex protocol processing capabilities and response speed. For example, if there are 20 battery packs in a container, there may be as many as more than 2000 battery data needs to be uploaded. At this time, the general time to complete the upload of the entire container data may be as long as ten seconds. The application scenario is unacceptable. So we are also doing optimization and improvement. Our goal is to control the entire data upload within 500 milliseconds.

The energy storage system puts forward high requirements for safety and reliability. It also puts forward high requirements for reliability, system fault tolerance and protection capabilities of BMS. At present, there is a lack of reliability requirements in relevant standards. So we put forward requirements to ourselves to meet the requirements of 15 years of operation, and the failure rate should be less than 1000PPM.

Battery safety status analysis and early warning are very important. They are all talking about battery safety. We believe that there are three levels. One is the safety of the battery itself, that is, the battery itself will not burn. The second is early warning protection. How to make early warning for possible thermal runaway, short circuit and other combustion accidents? this is very important. Of course, fire fighting is the last resort. What we want to see is the very early detection and warning when the battery may be dangerous. This is a function that the BMS needs to do in the future.

In summary, there is a big difference between energy storage BMS and automobile BMS. Many people have switched from making automobiles. Automobile BMS is relatively early. It was done in 2004 at the earliest, and energy storage was gradually implemented in 2008. . Many people say what difference does BMS make to energy storage? Energy storage systems are more complex, larger, require higher life span, and require faster response speed, so this is still different.