How Can Improve The Reliability of Energy Storage Battery Management System?

BMS is the Indispensable Component of Lithium Battery Energy Storage

The battery management system is an electronic device that can manage and monitor the energy storage lithium battery, through the collection and calculation of voltage, current, temperature and SOC parameters, and then control the process of charging and discharging the battery to achieve the protection of the lithium battery and improve the comprehensive performance of the lithium battery.

With the rapid development of energy storage batteries, large battery arrays can be used as backup and continuous power supply energy storage system, this energy storage system is receiving more and more attention to Germany and Australia, the number of installed home batteries doubled every year also proves this point. Home energy storage battery systems are continuously charged by the grid or other plot energy sources and then supplied to the user with alternating current (AC) via a DC/AC inverter.

The use of lithium batteries as backup power is not new, there are already many kinds of battery backup power systems, such as the basic 120/240V AC and hundreds of watts of power desktop PC short-term backup power system, ships, hybrid cars or all-electric type of car use several kilowatts of special vehicle backup power system, telecommunications systems and data centers use grid-level hundreds of kilowatts of backup power system ...etc. While advances in the field of lithium battery chemistry and lithium battery technology have attracted a great deal of attention, there is an equally critical component to a viable and battery-based backup system, and that is the battery management system (BMS).

The battery management system is an electronic device that can manage and monitor the energy storage lithium battery, through the collection and calculation of parameters such as voltage, current, temperature and SOC, and then control the process of charging and discharging the battery to achieve the protection of the lithium battery and improve the overall performance of the lithium battery.

The backup power supply for Li-ion batteries is suitable for fixed and mobile use from several kilowatts to hundreds of kilowatts of power and can provide a reliable and efficient power supply for a variety of uses.

There are many challenges in completing a battery management system for energy storage battery use, and the solution is never a simple "extension" of the management system from a small, lower-capacity lithium battery pack. Instead, new, more complex strategies and critical support components are required.

The starting point of the challenge is that the measurement of many important lithium battery parameters are required to have a high degree of accuracy and credibility. In addition, the planning of the subsystem must be modular, to be able to use the specific needs of the configuration to customize, but also to consider the possible expansion requirements, the overall management issues and the necessary maintenance.

The operating environment of a large-scale battery energy storage system also presents other significant challenges. In the case of high inverter voltage/current and therefore current spikes, the BMS must also be in a very noisy electrical environment and often very high-temperature environment to supply accurate, common data. In addition, the BMS must also supply a wide range of "fine" data for the internal module and system temperature measurements, rather than a limited number of rough aggregate data, because these data are critical for charging, monitoring and discharging.

Because of the important role of these power systems, their reliability of operation is inherently critical. To make the above easily stated goal a reality, the BMS must ensure data accuracy and integrity as well as continuous health assessment so that the BMS can continue to take the required action. To accomplish solid planning and reliable security is a multi-level process, the BMS must anticipate possible problems for all subsystems, perform self-testing and supply fault detection, and then select the appropriate action in standby and working modes. The last requirement is that the BMS must meet many stringent regulatory standards because of the high voltage, high current and high power.

BMS Planning Transforms Concepts Into Real-world Results

While overseeing a rechargeable battery is conceptually simple, simply placing voltage and current measurement circuits at the battery terminals, the reality of a BMS is very different and much more complex.

Robust planning begins with the comprehensive supervision of each battery section, which imitates the function of the circuit has made some important requirements. The BMS must evaluate the validity of each measurement because it needs to maximize data integrity, and the BMS must also identify erroneous or problematic readings. the BMS cannot ignore unusual readings because such readings may indicate potential problems, but at the same time, the BMS cannot act on erroneous data. The BMS cannot act on data that is incorrect.

Why do you need a BMS for Li-ion battery storage?

Safety requirements:

The disadvantage of Li-ion battery storage is that it is "delicate" and may cause permanent damage to the battery in a single over-discharge. In extreme cases, overheating or overcharging of lithium batteries can lead to thermal runaway, battery rupture or even explosion. So lithium batteries need BMS to strictly control the charging and discharging process to avoid overcharging and discharging, as well as overheating.

Functional requirements:

Energy storage lithium batteries need to know the SOC parameters of the lithium battery during use and predict the remaining power of the battery through SOC. the BMS can measure the SOC of the lithium battery in real-time to meet the customer's application needs.

BMS can change the inconsistency of the battery by equalization and improve the overall performance of the lithium battery.

Li-ion batteries will have different working performances at different temperatures, the best working temperature of Li-ion is 25-40℃. The change of temperature will change the SOC, open-circuit voltage, internal resistance, and available power of the battery, and even affect the life of the battery. The BMS can control the operating environment temperature of the battery and improve the characteristics of the battery.