(1) Data Acquisition
To ensure battery safety, the system performs real-time acquisition of the terminal voltage and temperature of each cell, charge/discharge current, and total battery pack voltage during the charging and discharging processes. This prevents overcharging or over-discharging. It involves collecting data on cell temperature and power circuit temperature. Cell temperature is typically measured using wire-type NTC thermistors, while power terminals generally use surface-mount NTC resistors.
To ensure battery safety, the system performs real-time acquisition of the terminal voltage and temperature of each cell, charge/discharge current, and total battery pack voltage during the charging and discharging processes. This prevents overcharging or over-discharging. It involves collecting data on cell temperature and power circuit temperature. Cell temperature is typically measured using wire-type NTC thermistors, while power terminals generally use surface-mount NTC resistors.
(2) SOX Algorithm Estimation
This includes SOC, SOE, and SOP. Accurately estimating the State of Charge (SOC)—the remaining battery capacity—ensures the SOC remains within a reasonable range. This prevents damage from overcharging or over-discharging and allows for real-time prediction of remaining energy or the state of charge.
This includes SOC, SOE, and SOP. Accurately estimating the State of Charge (SOC)—the remaining battery capacity—ensures the SOC remains within a reasonable range. This prevents damage from overcharging or over-discharging and allows for real-time prediction of remaining energy or the state of charge.
- SOC Estimation Methods:
- Traditional: Ampere-hour integration method, Open Circuit Voltage (OCV) method.
- Model-based: Kalman filtering, Particle filtering algorithms.
- Neural Networks: Neural network algorithms.
- State of Power (SOP) Algorithm: Determines maximum continuous and instantaneous charge/discharge power by looking up tables based on the battery's SOC and temperature. The cell's depolarization speed dictates the frequency of maximum power usage. When the accumulation speed of Li-ions on the SEI film surface exceeds the absorption speed of the anode, voltage drops occur, making it impossible to sustain maximum power. Therefore, the challenge in SOP calculation lies in the transition between peak power and continuous power.
- State of Health (SOH) Algorithm: Determines two accurate SOC values based on the OCV-SOC curve, calculates the accumulated charge or discharge (Ampere-hour integration) between these two SOC points to derive the battery capacity, and subsequently calculates the SOH.
(3) Safety Diagnostics
- Overcurrent Protection: Includes charging and discharging overcurrent protection. Generally, two levels of protection are implemented for functional safety: Level 1 is software-based, and Level 2 is hardware-based.
- Overvoltage Protection: Occurs during charging, divided into Level 1 and Level 2 overvoltage protection.
- Undervoltage Protection: Occurs during discharging, divided into Level 1 and Level 2 undervoltage protection.
- Temperature Protection: Includes high-temperature protection (charging/discharging) and low-temperature protection (charging/discharging).
- Short-circuit Protection: Includes short-circuit protection current and short-circuit protection time.
(4) Energy Management
Battery energy storage systems typically consist of hundreds or even thousands of cells, each with slightly different capacities and internal resistances. As operating time increases, these differences grow as each cell degrades at a different rate. If cell voltages are unbalanced, the battery pack will quickly reach a state of unusability. Battery balancing (equalization charging) is used to bring all cells in the pack to a uniform and consistent state.
Battery energy storage systems typically consist of hundreds or even thousands of cells, each with slightly different capacities and internal resistances. As operating time increases, these differences grow as each cell degrades at a different rate. If cell voltages are unbalanced, the battery pack will quickly reach a state of unusability. Battery balancing (equalization charging) is used to bring all cells in the pack to a uniform and consistent state.
(5) Information Management
BMS is categorized into purely hardware-based protection boards and those combining software with hardware.
BMS is categorized into purely hardware-based protection boards and those combining software with hardware.
- Pure Hardware BMS: Operates with a fixed set of protection parameters, providing protection and recovery based on acquired voltage, current, and temperature states without MCU intervention.
- Software + Hardware: The MCU enables real-time information acquisition and interacts externally via communication protocols like CAN or RS485, uploading real-time data from the BMS protection board.