SLYY218 December   2022 BQ79731-Q1

 

  1.   At a glance
  2.   Authors
  3.   3
  4.   The working principle of a BMS and industry trends
  5.   New battery chemistries
  6.   Wireless BMS
  7.   Advanced estimations of battery capacity and battery health
  8.   A detailed look at the cell supervisor unit (CSU)
  9.   Traditional vs. intelligent battery junction box (BJB)
  10.   A detailed look at the BJB
  11.   A detailed look at the battery control unit (BCU)
  12.   Creating a complete battery test environment ecosystem
  13.   Conclusion
  14.   Additional resource

The working principle of a BMS and industry trends

A distributed BMS architecture (Figure 1) has a modular structure and typically comprises three major subsystems: the cell supervision unit (CSU), the battery control unit (BCU) and the battery disconnect unit (BDU).

GUID-20221206-SS0I-BCZW-7KQ0-GSGV4QJPLTVG-low.png Figure 1 A typical BMS architecture.

The industry has different names for these subsystems, listed in Table 1, so it can be helpful to set a baseline for the various names and acronyms.

Table 1 Common industry acronyms for BMS subsystems.
Subsystem Name Also Referred to as: Acronyms
Cell supervisor unit Cell supervision circuit
Cell monitor unit		 CSU
CSC
CMU
Battery control unit Battery electrical controller
Battery energy control module
Battery management unit		 BCU
BEC
BECM
BMU
Battery disconnect unit Battery junction box BDU
BJB

The CSU collects parametric information from all battery cells by sensing the voltage and temperature of each cell. The CSU helps compensate for inconsistencies between battery cells by performing cell balancing. The BCU must incorporate the parametric information from the CSUs and must also detect the voltage and current of the battery pack to perform pack management. According to all collected voltage, current and temperature data, the BCU is responsible for allocating how to charge and discharge the battery according to the overall condition of each and every battery cell. Continuous monitoring of the condition of the batteries occurs through calculations of state of charge, state of power and state of health. Intelligent protection control is also an important feature of the BCU, as it must perform insulation monitoring, control the contactors in the event of a crash or short circuit, continuously monitor the temperature sensors, and perform diagnostics to check that all incoming parameters are indeed valid. The information is transmitted to the automobile vehicle control unit or electronic control unit through Controller Area Network (CAN) communication.