How Innovation in Battery Management Systems is Increasing EV Adoption
At a glance
 1 The working principle of a BMS and
industry trends | Review how integrating the three major BMS subsystems enables safe,
efficient battery packs, and explore new battery chemistries and BMS trends,
including wireless BMS. |
| 2 Advanced estimations of battery capacity
and battery health | An accurate estimation of a battery’s remaining charge has a direct effect
on the remaining driving range. Take a detailed look at the cell supervisor
unit (CSU) and how it provides increasingly detailed cell status
measurements to maximize the battery pack benefits. |
| 3 Traditional vs. intelligent battery
junction box (BJB) | Discover how silicon innovations are enabling a shift toward a more modern
architecture known as the intelligent BJB, and learn about the role of the
battery control unit (BCU) as the communication interface. |
Authors
The BMS protects the battery from damage, extends the life of the battery with intelligent charging and discharging algorithms, predicts how much battery life is left, and maintains the battery in an operational condition. Lithium-ion battery cells present significant challenges, demanding a sophisticated electronic control system. Plus, there is a significant risk of injury from fires and explosions. A BMS therefore requires cutting-edge silicon to meet all performance, safety and cost metrics.
In general, the three main BMS challenges that every designer strives to improve are maximizing driving range, improving cost and enhancing safety.
Solving one of these challenges may adversely impact the other. In this white paper, we’ll discuss several emerging trends to address all three challenges.
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).
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.
| 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.
