Choosing a good BMU is the key to BMS performance

There are usually two types of evaluations and predictions for battery status, namely State of Charge (SOC) and State of Health (SOH). SOC represents the remaining charge of the battery, while SOH reflects the health level and service life of the battery.
BMU can accurately calculate the remaining charge of the battery, i.e. SOC, through real-time monitoring of voltage, current, temperature and other data, which is crucial for energy efficiency management of energy storage products. And BMU can also predict the health status of the battery, namely SOH, which helps to detect potential problems in advance and extend battery life.
As a part of BMS, BMU works together with Battery Cluster Management (BCMU) and Battery Stack Management (BAMS) to achieve comprehensive management and protection of batteries. BMU collects various individual cell information (voltage, temperature) of the battery, calculates and analyzes the SOC and SOH of the battery, achieves active balancing of individual cells, and uploads abnormal cell information to the battery pack unit layer BCMU.
If we make an analogy, BMU is equivalent to the "frontline sentinel" responsible for low-level data collection and preliminary processing in BMS, which ensures the safety and efficiency of the battery pack and is the foundation for the normal operation of BMS. By closely collaborating with other levels of BMS, BMU can achieve comprehensive monitoring and fine management of battery status.

How to choose a good BMU?

For BMUs, the primary focus is on precise monitoring capabilities. High quality BMUs should have high-precision voltage, current, and temperature sensors to ensure accurate monitoring of battery status. And it has a high-performance data acquisition circuit that can obtain various parameters of the battery in real time and accurately.
In addition, a certain level of communication capability is required to seamlessly communicate with other parts of the BMS, supporting standard protocols such as CANbus, RS485, or I2C. At the same time, Yao selects BMUs that support passive or active balancing according to application requirements to ensure the consistency of the battery pack.
Many domestic and foreign enterprises have launched corresponding BMU products, such as TI's TIDA-010271, which retains UART communication for debugging or CAN architecture evaluation, expands NTC channels to meet a 1:1 ratio with the battery cell, and reserves channels for EEPROM and TMUX diagnosis. At the same time, it integrates 240mA internal balanced current and has automatic thermal management function.
The BMU30 series from Dongfang Motor provides a wide range of speed regulation, suitable for applications that require a fixed torque from low to high speeds, and can achieve stable speed control.
In addition, companies such as Maxim, TI, NXP, etc. also provide a series of ICs for battery monitoring and management, which can serve as core components for building BMUs.
The BMU-S64T52CP1 from Huasu Technology in China is designed for liquid cooling systems, with built-in gas and leakage detection. It integrates battery pack level fire detection and control, as well as single cell AC internal resistance detection, providing a solution for battery warning and SOH calculation.
Huawei Digital Energy has also launched a corresponding BMU, but it is not launched separately, but as part of the BMS, consisting of BCU and BMU. BMU is responsible for battery cell voltage, temperature sampling, and battery balancing, and has the characteristics of high and low voltage compatibility, high-precision SOC error less than ± 3%, etc.
There are also BMU products launched by Jiangsu Haishang New Energy, including BMU-YH01-02, BMU-YE02-02-13 (32S), BMU-YH02-03, and BMU-YE01-03. These products support battery systems with different voltage ranges, such as 800-1500VDC or 80-1000VDC, and have CAN bus communication capabilities. They support different system architectures, including secondary and tertiary architectures, and have multiple communication interfaces, such as 2 CAN+2 485+1 TCP/IP+1 WiFi (optional). They also have temperature sampling accuracy of ± 1 ℃, current sampling accuracy of 2 ‰, and support multiple power supply methods, including battery cluster power supply or external 24V.
Each company's BMU product has its unique features and advantages, such as support for different battery types, durability in special environments, advanced algorithms, and more. When choosing BMU, engineers should carefully evaluate its specific needs and application environment to determine the most suitable product.
Summary
Choosing a good BMU requires comprehensive consideration of multiple factors such as monitoring accuracy, protection mechanisms, balanced management capabilities, data management, and system security. There are many companies in the market that have launched BMU products with different characteristics. Engineers should choose the most suitable BMU based on specific application needs and technical requirements to ensure the efficient, safe, and reliable operation of battery management systems.