What are the functional modules of a battery management system?

The functional modules of a battery management system (BMS) usually include the following key parts, which work together to achieve comprehensive monitoring, control, protection and optimization of the battery pack:

1. Data acquisition module

Battery terminal module: mainly responsible for data acquisition, including voltage parameters, current parameters, temperature, communication signals, etc. This is the most basic module in BMS, which obtains the status information of the battery pack in real time through sensors.

Voltage acquisition: Use a high-precision analog-to-digital converter (ADC) to measure the voltage of a battery cell or battery pack. Common ADC chips include Texas Instruments (TI)'s ADS127L01, etc. These chips have the characteristics of high precision and low noise, and are suitable for battery voltage measurement.

Current acquisition: Use Hall effect sensors or shunts to measure the charge and discharge current of the battery pack. For example, the FS500E2 Hall current sensor can be used to measure large currents, while the ACS714 linear Hall current sensor is suitable for measuring smaller balancing currents.

Temperature acquisition: Use a thermistor or a digital temperature sensor (such as DS18B20) to monitor the temperature of the battery. These sensors are usually used with ADC to convert temperature signals into digital signals for processing.

2. Display module Display module: mainly for data presentation and human-computer interaction. Users can intuitively understand the current status of the battery pack, such as power, temperature, fault information, etc. through the display module.

The display module may use various types of displays, such as LCD display or OLED display. These displays are usually connected to a microcontroller (MCU) and the display content is controlled by the MCU.

3. Battery parameter detection module

This module is responsible for detailed detection of various parameters of the battery, including total voltage, total current, single cell voltage (to prevent overcharging, overdischarging and even reverse polarity), temperature (it is best to have a temperature sensor for each string of batteries, key cable connectors, etc.), smoke detection (monitoring electrolyte leakage), insulation detection (monitoring leakage), collision detection, etc.

This module may contain multiple sensors and ADCs for measuring parameters such as voltage, current, temperature, etc. In addition to the ADCs and sensors mentioned above, dedicated battery monitoring chips may also be used, such as Intersil's ISL94203, which integrates multiple battery monitoring functions, such as voltage monitoring, current monitoring, temperature monitoring, etc.

4. Battery state estimation module

This module is used to estimate various states of the Replacement Battery, including state of charge (SOC), state of health (SOH), state of function (SOF), state of energy (SOE), fault and safety state (SOS), etc. These state information is crucial for the rational use and maintenance of the battery.

This module usually uses complex algorithms and advanced MCU or digital signal processor (DSP) to estimate the battery's SOC, SOH and other states. These processors need to have high-speed computing capabilities and a large amount of storage space to support the operation of complex algorithms.

Including fault detection, fault type judgment, fault location, fault information output and other functions. Through the collected sensor signals, the diagnostic algorithm is used to diagnose the fault type and provide early warning. This helps to promptly discover and deal with potential problems in the battery pack or related subsystems.

The fault diagnosis module may use a dedicated fault diagnosis chip or MCU to execute the diagnostic algorithm. These algorithms determine whether the battery or BMS is faulty based on the collected sensor data, and give the corresponding fault code or warning information.

6. Battery safety control and alarm module

This module is responsible for the safety control of the battery, including thermal system control, high-voltage electrical safety control, etc. When the BMS diagnoses a fault, it will notify the vehicle controller through the network and require it to take effective measures (the BMS can also cut off the main circuit power supply when it exceeds a certain threshold) to prevent damage to the battery and human body caused by high temperature, low temperature, overcharging, over-discharging, overcurrent, leakage, etc.

This module may contain hardware components such as relays and fuses to cut off the connection between the battery and the load or charger to ensure battery safety. At the same time, MCU or a dedicated safety control chip may also be used to execute safety control logic.

7. Charging control module

The BMS has a charging management module that can control the charger to charge the battery safely according to the characteristics of the battery, the temperature and the power level of the charger. This helps to ensure the safety and efficiency of the charging process.

The charging control module usually uses a charging management chip to control the charging process, such as TI's BQ series charging management chip. These chips can monitor the voltage, current and temperature of the battery, and adjust the charging current and voltage based on this information to ensure safe charging of the battery.

8. Battery balancing module

The battery balancing module is used to solve the voltage difference problem between single cells in the battery pack. It transfers the charge of high-voltage cells to low-voltage cells by controlling switches or adjusting current to achieve battery balancing. This helps improve the overall performance and life of the battery pack.

The battery balancing module may use a dedicated balancing chip or MCU to control the balancing process. These chips or MCUs achieve balancing between battery cells by controlling switch circuits or adjusting current.

9. Thermal management module

According to the temperature distribution information in the battery pack and the charging and discharging requirements, the intensity of active heating/cooling is determined so that the battery can work at the most suitable temperature as much as possible and give full play to the performance of the battery.

The thermal management module may contain hardware components such as temperature sensors, heating elements, cooling fans, and MCUs or dedicated thermal management chips that control these components. These chips or MCUs control the working state of heating or cooling elements according to battery temperature information to maintain the battery operating within a suitable temperature range.

10. Network communication module

Used to communicate with external systems, such as data exchange and command transmission with vehicle control systems or energy management systems. It can support various communication protocols, such as CAN bus, LIN bus or serial communication interface.

The network communication module usually uses chips such as CAN bus controller, LIN bus controller or Ethernet controller to achieve communication with external systems. These chips support standard communication protocols and interfaces, and can ensure the reliability and real-time performance of data and command transmission between BMS and vehicle control systems or energy management systems.

11. Other functional modules

Depending on specific needs, BMS may also include functional modules such as real-time clock (RTC), memory, and battery authentication. Real-time clock and memory are used in black box applications, where RTC is used for timestamps and memory is used to store data, allowing users to understand the behavior of the battery pack before a catastrophic event.

The functional modules of the battery management system cover data acquisition, display, parameter detection, state estimation, fault diagnosis, safety control, charging control, battery balancing, thermal management, network communication and other aspects to ensure the safe, reliable and efficient operation of the battery pack.