BMS Software Development Essentials for New Energy Vehicles

The BMS (Battery Management System) is a core electronic system in new energy vehicles, responsible for monitoring, protecting, balancing, and estimating the state of traction battery packs. BMS software quality directly affects battery safety and vehicle performance. This article outlines key software development considerations.

    BMS Software Architecture

    Typical BMS software uses layered architecture: driver layer handles AFE chip communication and temperature/voltage acquisition; middleware implements data filtering and fault diagnosis; application layer performs SOC/SOH estimation, balancing control, thermal management, and CAN communication with the vehicle VCU. In product development practice, modular design with standard interfaces between modules facilitates unit testing and feature expansion.

    SOC State Estimation

    State of Charge (SOC) estimation is among the most critical BMS algorithms. Common methods include:
    1. Coulomb counting: Integrates charge/discharge current; simple but accumulates error.
    2. Open Circuit Voltage (OCV): Uses battery OCV-SOC relationship for correction; suitable during rest periods.
    3. Kalman filtering: Combines equivalent circuit models with voltage, current, and temperature data; high accuracy but computationally intensive.
    Production systems typically use fused approaches achieving ±5% accuracy across all operating conditions.

    Safety Protection Strategies

    BMS must implement multi-level protection: Level 1 limits charge/discharge current via software logic; Level 2 cuts main relay via hardware comparators on severe faults; Level 3 relies on fuses as the last line of defense. Fault diagnosis must cover over-voltage, under-voltage, over-current, over-temperature, insulation failure, communication timeout, and dozens of other scenarios.

    Communication and Diagnostics

    BMS communicates with VCU and OBC via CAN bus following OEM-defined DBC protocols. Diagnostic functions should support UDS protocol for DTC storage, parameter calibration, and OTA firmware updates. Comprehensive test cases should cover normal operation, boundary conditions, and fault injection scenarios.

    Shoulder Tech has extensive NEV BMS development experience, providing end-to-end embedded development from algorithm design to vehicle integration.

   Shanghai Shoulder Tech provides professional product solutions including product development, circuit design, solution design, and industrial equipment R&D for automotive electronics, smart agriculture, and smart home applications. Tel: 021-61319007 Contact: Manager Ma 13918912514