Battery Management System (BMS) for Energy Storage Systems

火辣西米秀

Battery Management System (BMS) for Energy Storage Systems [Copy link]

Battery Management System (BMS)

A complete electrochemical energy storage system is mainly composed of battery packs, battery management systems (BMS), energy management systems (EMS), power storage converters (PCS) and other electrical equipment.

In the energy storage system, the battery pack feeds back status information to the battery management system BMS, which shares it with the energy management system EMS and the energy storage inverter PCS; the EMS sends control information to the PCS and BMS based on optimization and scheduling decisions to control the single cell/battery pack to complete charging and discharging.

Battery Management System BMS : plays a sensing role and is mainly responsible for battery monitoring, evaluation, protection and balancing;

Energy Management System EMS : plays a decision-making role and is mainly responsible for data collection, network monitoring and energy scheduling;

Energy storage converter PCS : plays an executive role, and its main function is to control the charging and discharging process of the energy storage battery pack and perform AC/DC conversion.

What is a Battery Management System (BMS)

BMS stands for Battery Management System. It is a device that monitors the status of energy storage batteries. It is mainly used to intelligently manage and maintain each battery unit; prevent overcharging and over-discharging of the battery, and extend the battery life; collect battery status information in real time, and upload data to the background for remote monitoring. It is one of the core subsystems of the energy storage battery system.

BMS system three-layer architecture:

1) Bottom layer: slave control BMU - single cell management layer . It is composed of battery monitoring chip and its auxiliary circuits, responsible for collecting various information of single cells, calculating and analyzing the battery's SOC (remaining battery capacity) and SOH (battery health status), realizing active balancing of single cells, and uploading single cell abnormal information to the master control.

2) Middle layer: Main control BCU - battery pack management layer . Collects various single battery information uploaded by BMU and collects battery pack information. Calculates and analyzes the SOC and SOH of the battery pack.

3) Upper layer: General control - battery cluster management layer . Responsible for the overall coordination within the system and external information interaction with EMS and PCS, and controls the operation process of the entire BMS system according to external requests.

Specific functions of battery management system BMS

01. Single cell voltage equalization function

This function is to correct the discreteness of voltage or energy caused by the process differences of the battery cells in the series battery pack, to avoid the occurrence of battery performance deterioration or even damage due to overcharge or overdischarge of individual single cells, so that the voltage differences of all individual batteries are within a certain reasonable range. The error between each battery is required to be less than ±30mv.

02.Battery protection function

Single cell overvoltage, undervoltage, overtemperature alarm, battery pack overcharge, overdischarge, overcurrent alarm protection, cutoff, etc.

03.Data collection function

The collected data mainly include: single cell voltage, single cell temperature, group terminal voltage, charge and discharge current, and the internal resistance of the battery is calculated.

04. SOC/SOH diagnostic function

Based on the real-time measurement of battery module voltage, charge and discharge current, temperature, single cell terminal voltage, calculated battery internal resistance and other parameters, the diagnosis model is analyzed to diagnose the current capacity or remaining capacity (SOC) of the single cell, the diagnosis of the health state (SOH) of the single cell, the battery pack status assessment, and the estimation of the sustainable discharge time in the current state during discharge.

05. Thermal Management

During the charging process, the battery module will generate a large amount of heat energy, which will increase the temperature of the entire battery module. Therefore, BMS thermal management comes into being.

06. Fault diagnosis and fault tolerance

If an abnormality occurs, the BMS will give a fault diagnosis alarm signal, which will be sent to the upper control system through the monitoring network to determine the faulty battery and locate it, give an alarm signal, and take appropriate treatment measures for these batteries. Among them, technologies such as battery bypass or energy transfer can prevent the operation of the entire battery group from being affected when a single battery fails.

Application of laser welding technology

Laser welding refers to a welding method that uses the heat of a laser beam to melt and fuse the workpiece. Specifically, it uses the high power energy and excellent directionality of the laser beam to focus the laser beam in a very small area through the focusing system in the laser welding machine, forming a heat source area with highly concentrated energy at the welding point in a very short time, thereby melting the welded material and forming a strong weld point and weld.

The application of laser welding technology in the production of lithium batteries, such as cell manufacturing, PACK manufacturing, and the connection of battery management systems (BMS), has greatly improved the precision, efficiency, and reliability of product manufacturing.

Functional upgrade: Deep integration of big data management and cloud-edge collaboration

BMS equipment is an important component of building a cloud-edge combined energy storage system big data platform and deep mining and analysis functions.

At present, the functions of BMS have developed from basic functions such as monitoring, communication, protection, display, and storage to advanced functions such as battery system safety diagnosis and long-life operation and maintenance, and system economic index diagnosis. From a technical point of view, active balancing technology will become the standard, and technologies such as big data and artificial intelligence will be applied to battery status algorithms; in the future, the survival space of low-end BMS suppliers will become smaller and smaller. Intelligent operation and maintenance, advanced functions, etc. are the core points for differentiated competition among manufacturers in the future.

Edge : Develop cloud-edge collaboration based on BMS, give full play to the data aggregation capabilities of BMS, realize real-time data collection, analysis, status diagnosis and evaluation of the battery system at the station-level equipment end, and realize data cleaning and pre-processing.

Cloud : Based on data from more stations, the cloud can mine, refine and process multi-dimensional spatiotemporal data, achieve more detailed and comprehensive evaluation of battery operating status, safety status and reliability of energy storage systems, dynamically optimize BMS operation strategies and algorithm models and assign them to the equipment side, so as to achieve the best safe and economic operation and maintenance mode, realize intelligent operation and maintenance, provide data support for energy aggregation/distribution/trading, and provide guarantee for the realization of the value of energy storage systems.