What are the functional modules of a battery management system?

The primary components of a battery management system (BMS) consist of several functional modules that collaborate to ensure comprehensive control, monitoring, protection, and optimization of the battery pack:

1. Data acquisition module

Battery terminal module: This module takes charge of gathering data including voltage, current, temperature, and communication signals. Serving as the most fundamental part of the BMS, it collects real-time status data from the battery pack utilizing sensors.

Voltage acquisition: High-precision analog-to-digital converters (ADCs) measure the voltage of individual battery cells or the entire battery pack. High-performance ADC chips, like the Texas Instruments (TI) ADS127L01, are recommended due to their precision and low noise levels which are essential for accurate battery voltage measurements.

Current acquisition: The process utilizes Hall effect sensors or shunts to track the charging and discharging current of the battery pack. For instance, the FS500E2 Hall current sensor is ideal for measuring large currents, while the ACS714 linear Hall current sensor is perfect for smaller balancing currents.

Temperature acquisition: This involves the use of thermistors or digital temperature sensors, such as the DS18B20, to monitor the battery's temperature. In most cases, these sensors work with AD converters to transform temperature signals into digital data for further analysis.

2. Display module: This element is primarily dedicated to data visualization and user interaction. Through the display module, users gain intuitive insights into the battery pack's current conditions, such as power levels, temperatures, and fault notifications.

Various types of displays, including LCD and OLED screens, can be employed within this module. Typically, these displays connect to a microcontroller (MCU), with the MCU managing the display content.

3. Battery parameter detection module: This module focuses on the in-depth assessment of numerous battery parameters. These encompass overall voltage, total current, single-cell voltage checks (to avert overcharging, excessive discharging, and reverse polarity), and temperature readings (ideally, having a temperature sensor for each battery string and critical cable connectors).

Moreover, this module also performs smoke detection, insulation detection, and collision detection. It typically comprises multiple sensors and AD converters designed for measuring these various parameters. Specialized battery monitoring chips, such as Intersil's ISL94203, can integrate multiple monitoring functions including voltage, current, and temperature checks.

4. Battery state estimation module: This component estimates various critical states of the Replacement Battery, such as state of charge (SOC), state of health (SOH), state of function (SOF), and state of energy (SOE), as well as fault and safety states (SOS). Such information is essential for the effective use and maintenance of the battery.

Typically, this module employs sophisticated algorithms and advanced MCUs or digital signal processors (DSPs) to accurately predict SOC, SOH, and related statuses. The processors utilized require rapid computational abilities and extensive storage to handle complex algorithmic processes.

5. Fault diagnosis module: This segment encompasses fault detection, fault type classification, fault localization, and the output of fault information. Using data gathered from sensors, diagnostic algorithms help identify fault types and generate alerts, helping to swiftly uncover and resolve potential issues within the battery pack or associated subsystems.

The fault diagnosis module may incorporate a dedicated diagnosis chip or MCU to execute the necessary diagnostic algorithms. These algorithms analyze collected sensor data to ascertain whether either the battery or BMS is malfunctioning, providing corresponding error codes or warning messages as needed.

6. Battery safety control and alarm module: This module oversees battery safety by regulating thermal systems, high-voltage electrical safety measures, and more. In the event a fault is diagnosed by the BMS, it communicates with the vehicle controller via the network, prompting it to enact effective precautionary measures – such as cutting off main circuit power when thresholds are exceeded – to avert damage from causes such as excessive temperatures, overcharging, or battery leakage.

This module often includes hardware components like relays and fuses aimed at severing connections between the battery and load or charger to maintain safety. Additionally, an MCU or designated safety control chip may execute the safety management logic.

7. Charging control module: This aspect of the BMS manages the charging process, ensuring the battery is charged securely in accordance with its specific characteristics, as well as temperature and charger capacity factors, thereby optimizing safety and efficiency.

The charging control module generally employs a charging management chip, such as TI’s BQ series, to regulate the charging activities. These chips monitor battery voltage, current, and temperature, adjusting the charging current and voltage based on this data to facilitate safe battery charging.

8. Battery balancing module: This module tackles any voltage discrepancies among the cells in the battery pack. It redistributes charge from higher voltage cells to lower voltage ones, employing switches or current adjustments to establish balance, which enhances overall performance and lifespan of the battery pack.

Specialized balancing chips or MCUs may direct this balancing process, utilizing control circuits to promote balance among battery cells through precise switch operation or current regulation.

9. Thermal management module: This module gauges temperature distribution within the battery pack and adjusts heating or cooling processes to maintain optimal battery operating temperatures, maximizing performance.

The thermal management module integrates hardware components like temperature sensors, heating elements, cooling fans, as well as MCUs or specialized thermal management chips to monitor and control the operation of these components based on battery temperature feedback.

10. Network communication module: This part of the BMS facilitates communication with external systems, including data and command exchanges with vehicle control or energy management systems. Various communication protocols can be supported such as CAN bus, LIN bus, or serial communication interfaces.

Typically, the network communication module consists of chips such as CAN bus controllers, LIN bus controllers, or Ethernet controllers, which ensure communication with external systems operates reliably and in real-time.

11. Other functional modules: Depending on specific requirements, the BMS may encompass additional modules, such as real-time clocks (RTC), memory, and battery authentication systems. RTCs are utilized for timestamps while memory serves to store data, providing insights into battery pack behavior before any critical events occur.

The functional modules of the battery management system encompass aspects such as data acquisition, visualization, parameter detection, state estimations, fault diagnoses, safety controls, charging management, balancing, thermal management, network communication, and more, ensuring the battery pack operates safely, reliably, and efficiently.