What Is an Automotive Battery Management System？
An automotive battery management system is a system designed to control the safe operation of on-board lithium-ion batteries installed in vehicles such as electric vehicles (EVs) and hybrid cars.
Generally, systems that manage the safety of secondary batteries such as lithium-ion batteries are referred to as Battery Management Systems (BMS). The automotive battery management system is a specialized system within BMS tailored for on-board vehicle batteries. While lithium-ion batteries offer high efficiency and energy density, they also pose risks such as fire or smoke, necessitating precise control. Using an automotive battery management system enables safe and efficient battery operation.
Applications of Automotive Battery Management Systems
The primary purpose of an automotive battery management system is to control vehicle batteries effectively, enhancing safety and performance. Additionally, it is expected to extend battery life through proper battery usage.
The main vehicles where automotive battery management systems are used include:
- Hybrid Electric Vehicles (HEVs)
- Plug-in Hybrid Electric Vehicles (PHEVs)
- Battery Electric Vehicles (BEVs)
- Full Hybrid Electric Vehicles (FHEVs)
- Commercial and Agricultural Vehicles (CAVs)
- Low-speed Electric Vehicles
- Electric Two-Wheelers/Three-Wheelers
Principle of Automotive Battery Management Systems
The automotive battery management system monitors and controls the charging and discharging of batteries through electronic control circuits. Specific monitoring parameters include:
- Voltage
- Temperature
- Capacity
- State of charge
- Power consumption
- Remaining operating time
- Charge cycles
Additionally, one of the roles of the battery management system is to prevent excessive stress on batteries. It includes features to prevent overcharging, over-discharging, and overcurrent in cells (individual battery cells within battery modules), caused by extreme rapid charging or high discharging currents.
Specific Functions
The main functions of an automotive battery management system include:
- Preventing cell overcharging and over-discharging
- Preventing excessive cell currents
- Managing cell temperatures
- Estimating battery capacity
- Balancing cell voltages (cell balancing)
The automotive battery management system measures the voltage, current, and temperature of cells (individual battery cells) within battery modules. If any parameter exceeds set limits, it disconnects output terminals to protect against overcharging, over-discharging, or overcurrent situations, thus controlling power supply based on battery capacity.
Furthermore, it balances cell voltages (cell balancing) to ensure that different battery cells within a battery pack maintain similar charge/discharge requirements.
System Components
The automotive battery management system comprises the following components:
- Voltage detection: Measures battery module and individual cell voltages
- Monitoring circuit: Monitors cell conditions and performs cell balancing
- Temperature detection: Measures temperatures of individual cells
- Control circuit: Controls BMS measurements and balancing operations
- Current detection: Measures overall unit current
- Voltage detection: Measures overall unit voltage
- Junction box: Disconnects in case of anomalies to protect the battery
- Ground fault detection: Detects unit-wide ground faults
Electronic components used include:
- Temperature sensors such as NTC thermistors
- Chip resistors for cell balancing and voltage measurement
- Control circuits like DC/DC converter circuits
- Conductive polymer aluminum electrolytic capacitors for noise reduction and smoothing
- Power inductors for voltage conversion
- Chip varistors for ESD noise suppression
Types of Automotive Battery Management Systems
Automotive battery management systems vary based on vehicle types such as Hybrid Electric Vehicles (HEVs), Plug-in Hybrid Electric Vehicles (PHEVs), Battery Electric Vehicles (BEVs), etc. It is essential to select the system based on vehicle type and other factors like the number of monitorable cells, battery voltage type (e.g., 12-24V or 48V), and voltage control precision. Specifically, high-voltage battery systems are appropriate for vehicles using high-voltage batteries.