BMS Battery Management System for Industrial & Commercial Energy Storage Two-Level Distributed Architecture: BMU + BCU

Core Positioning: Industrial and commercial energy storage BMS adopts a BMU + BCU two-level distributed architecture, achieving 'bottom-layer precise acquisition + upper-layer intelligent decision-making' separated coordination. It is the core control center ensuring safe operation, lifespan guarantee, and maximum performance for energy storage systems.

Part 1: System Overview — Two-Level Architecture, Each with its Role

Architecture: Consists of BMU (Battery Management Unit) + BCU (Battery Control Unit), with clear hierarchy and well-defined division of labor.

• BMU (Execution Layer): The 'nerve endings' of the system, directly facing cells, responsible for bottom-layer data acquisition and balance execution.

• BCU (Control Layer): The 'spinal cord center' of the system, aggregating data, running algorithms, executing logic, and managing external interfaces.

Communication: BMU <-> BCU via CAN bus — real-time, stable, and strongly anti-interference, adapting to the harsh conditions of industrial and commercial energy storage.

Part 2: BMU Battery Management Unit — Nerve Endings, Precise Sensing

Directly connected to cells/battery modules, it is the source of all data, has no computing pressure, and focuses on acquisition and execution.

2.1 Core Data Acquisition

• Cell Voltage Acquisition: Real-time monitoring of each cell's voltage, accuracy <= +/-5mV, providing the basis for balancing and protection.

• Multi-Point Temperature Acquisition: Acquires cell surface, terminal, busbar, and module ambient temperatures, covering key thermal risk points.

• Auxiliary Acquisition: Module total voltage, balance status feedback.

2.2 Battery Balancing Execution

Goal: Eliminate cell voltage differential, improve whole-pack capacity utilization, and delay battery degradation.

• Passive Balancing: Resistive energy dissipation type. Low cost, simple structure, suitable for small and medium capacity energy storage.

• Active Balancing: Energy transfer type. High efficiency, no heat generation, suitable for large-capacity/high-requirement industrial and commercial scenarios.

Part 3: BCU Battery Control Unit — Spinal Cord Center, Intelligent Decision-Making

The core brain of the system, aggregating all system data, running algorithms, executing protection, and interfacing with external devices.

3.1 Sampling and Measurement Module — Basic Data Support

• Basic Electrical Sampling: Cell voltage/temperature, battery cluster total voltage, charge/discharge current, insulation resistance.

• High-Voltage Safety Sampling: Insulation monitoring — real-time calculation of system ground insulation value, warning of leakage risk. HVIL (High-Voltage Interlock) — monitors high-voltage connector locking status, preventing loosening, arcing, and electric shock risks.

3.2 State Estimation Module — Core Algorithm Capability

Based on acquired data, precisely evaluates the battery's true state through model algorithms:

• SOC (State of Charge): Remaining energy estimation — ampere-hour integration + OCV calibration, accuracy <= +/-3%.

• SOH (State of Health): Battery lifespan/capacity degradation evaluation.

• SOP (State of Power): Maximum charge/discharge power available at current moment.

• SOE (State of Energy): Estimatable total releasable energy.

• Thermal State Estimation: Cell internal temperature extrapolation (higher than surface temperature).

• Safety Warning: Micro-short circuit, leakage current, and thermal runaway precursor monitoring.

3.3 Control and Management Module — Strategy Execution and Safety Protection

• Balance Management: Based on voltage differential thresholds, issues commands to control BMU to start/stop balancing, maintaining cell consistency.

• Thermal Management: Based on temperature data, automatically controls fans, liquid cooling pumps, and heaters to maintain the battery within the optimal range of 25C to 35C.

• Charge/Discharge and Safety Management:

• Multi-level protection: over-voltage, under-voltage, over-current, over-temperature, and low-temperature.

• On anomaly: immediate alarm -> limit power -> cut high-voltage contactor.

• Interfaces with PCS (Power Conversion System) and EMS (Energy Management System): reports allowed charge/discharge power, controls high-voltage on/off sequences, and executes dispatch commands.

Part 4: Architecture Value Summary

• Precise Acquisition: BMU acquires data nearby, avoiding long-distance transmission errors.

• Reliable Control: BCU makes centralized decisions, with unified logic and timely protection.

• High Expandability: Flexibly expands module/cluster count, adapting to various capacity scenarios in industrial and commercial applications.

• Safety Redundancy: Two-level separation means single-point faults do not affect the whole, improving system stability.

This two-level architecture is the standard mainstream solution for safe, efficient, and long-life operation of industrial and commercial energy storage.