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Automotive: Battery Management System

Overview​

This sample project demonstrates NirmIQ features for ISO 26262 compliant automotive systems. The Electric Vehicle Battery Management System (BMS) project showcases how to manage safety-critical requirements, perform DFMEA analysis, and maintain traceability for ASIL-D level components.

Project Details​

  • Domain: Automotive (Electric Vehicle)
  • System: Battery Management System (BMS)
  • Compliance Standard: ISO 26262 (ASIL-D)
  • Lifecycle Phase: Development & Verification
  • Organization: Sample - Automotive Industry
  • Custom ID Prefix: BMS

Features Demonstrated​

Requirements Management​

The project uses a 5-level requirement hierarchy following ISO 26262 structure:

  1. Customer Request (CR) - Top-level stakeholder needs

    • Example: "Battery management system shall provide safe operation at all times"
    • Custom IDs: BMS-CR-001, BMS-CR-002, etc.

  2. System Requirement (SYS) - System-level functional and safety requirements

    • Example: "System shall monitor cell voltage within ±5mV accuracy"
    • Custom IDs: BMS-SYS-001, BMS-SYS-002, etc.

  3. Subsystem Requirement (SUB) - Subsystem decomposition

    • Example: "Cell monitoring subsystem shall sample all cells every 100ms"
    • Custom IDs: BMS-SUB-001, BMS-SUB-002, etc.

  4. Function Requirement (FUN) - Functional specifications

    • Example: "Voltage measurement circuit shall use 16-bit ADC"
    • Custom IDs: BMS-FUN-001, BMS-FUN-002, etc.

  5. Sub-Function Requirement (SFUN) - Detailed implementation requirements

    • Example: "ADC calibration shall be performed on startup"
    • Custom IDs: BMS-SFUN-001, BMS-SFUN-002, etc.

Total Requirements: ~90 requirements covering:

  • Cell voltage monitoring
  • Temperature sensing
  • State of Charge (SoC) estimation
  • Balancing control
  • Safety shutdown mechanisms
  • Communication interfaces (CAN)

Advanced FMEA Analysis​

DFMEA Coverage:

  • 15 FMEA analyses for critical subsystems
  • 150 failure modes with complete S/O/D ratings
  • AIAG/VDA compliant Action Priority calculation
  • Focus areas:
    • Cell monitoring electronics
    • Voltage measurement circuitry
    • Over-voltage/under-voltage protection
    • Thermal management
    • Communication integrity

Example Analysis: "Cell Monitoring Subsystem DFMEA"

  • Component: Voltage sensing circuit
  • Failure Mode: Incorrect voltage reading
  • Severity: 9 (Safety-critical - could lead to thermal runaway)
  • Occurrence: 3 (Low, with proper component selection)
  • Detection: 4 (Self-test detects most failures)
  • RPN: 108 (High priority)
  • Action Priority: High (S ≥ 9)
  • Recommended Actions: Add redundant sensing, implement plausibility checks

Traceability Matrix​

Requirement Links:

  • Customer Requests → System Requirements (parent-child)
  • System Requirements → Subsystem Requirements (decomposition)
  • Functional Requirements → Test Cases (verification)
  • Safety Requirements → FMEA Analyses (hazard mitigation)

Coverage Metrics:

  • Traceability coverage: >90%
  • Test coverage: >85% for ASIL-D requirements
  • Compliance mapping: All safety requirements mapped to ISO 26262 clauses

Safety and Compliance​

ISO 26262 ASIL-D Requirements:

  • Battery voltage monitoring (ASIL-D)
  • Over-current protection (ASIL-D)
  • Thermal shutdown (ASIL-D)
  • Diagnostic coverage >99% for safety functions

Compliance Mappings:

  • Part 6 (Product development - Software)
  • Part 8 (Supporting processes)
  • Clause-by-clause requirement mapping

How to Use This Project​

1. Explore Requirements Hierarchy​

  1. Open the project:

    • From project list, select "Electric Vehicle Battery Management System"

  2. Navigate the hierarchy:

    • Start at Customer Request level (BMS-CR-001 to BMS-CR-005)
    • Expand each to see child System Requirements
    • Continue drilling down through 5 levels

  3. Observe requirement structure:

    • Note hierarchical custom IDs (BMS-CR-001 → BMS-SYS-003)
    • See parent-child relationships in left panel
    • Check requirement details in right panel

  4. View requirement graph:

    • Click "Graph" tab in right panel
    • See visual hierarchy and dependencies
    • Identify high-level vs low-level requirements

2. Review Advanced FMEA​

  1. Open FMEA module:

    • Click "FMEA" tab in main navigation
    • Select "Advanced FMEA" sub-tab

  2. Browse analyses:

    • See list of 15 DFMEA analyses
    • Look for "Cell Monitoring Subsystem DFMEA"
    • Click to open detailed view

  3. Examine failure modes:

    • Review 10 failure modes per analysis
    • Check S/O/D ratings (1-10 scale)
    • Note automatically calculated RPN and Action Priority

  4. Use Risk Heatmap:

    • Click "Risk Heatmap" tab
    • See color-coded visualization:
      • Red = High risk (S ≥ 9 or high S+O+D)
      • Yellow = Medium risk
      • Green = Low risk
    • Identify which failure modes need immediate action

  5. Track RPN trending:

    • Click "RPN Trend" tab
    • See how RPN values change over time
    • Monitor effectiveness of corrective actions

3. Check Traceability​

  1. Open Analytics:

    • Click "Analytics" tab
    • Select "Traceability Matrix" sub-tab

  2. View requirement links:

    • See source-target relationships
    • Filter by requirement type
    • Check coverage statistics

  3. Verify test coverage:

    • Click "Coverage" sub-tab
    • See percentage of requirements with test cases
    • Identify gaps in verification

4. Explore Compliance Mapping​

  1. Open Analytics → Compliance:

    • See ISO 26262 clause mappings
    • Check compliance status per requirement
    • View evidence documentation

  2. Generate compliance report:

    • Export traceability matrix
    • Generate coverage report
    • Create audit-ready documentation

Key Learning Points​

Requirements Management​

  • Hierarchical structuring for complex automotive systems
  • Custom ID schemes for traceability (BMS-CR, BMS-SYS, etc.)
  • Safety requirement decomposition from ASIL-D to component level
  • Parent-child relationships for impact analysis

FMEA Best Practices​

  • DFMEA for electronics: How to analyze circuit-level failures
  • AIAG/VDA Action Priority: Automatic calculation based on S/O/D
  • Risk prioritization: Using heatmaps to focus on critical items
  • Action tracking: Managing corrective actions for high RPN items

ISO 26262 Compliance​

  • Requirement decomposition per safety lifecycle
  • Traceability to standard clause-by-clause
  • Verification tracking via test case linkage
  • Safety analysis integration (FMEA + requirements)

Real-world Application​

  • Multi-level hierarchies common in automotive
  • Safety-critical requirements need rigorous tracing
  • DFMEA is mandatory for ISO 26262 compliance
  • Tool-supported traceability reduces certification effort

Tips for Adapting to Your Project​

  1. Custom ID Scheme: Replace "BMS" prefix with your project acronym
  2. Hierarchy Levels: Adjust to your organization's standard (3-7 levels typical)
  3. ASIL Levels: Mark requirements with appropriate ASIL (A/B/C/D)
  4. FMEA Focus: Start with highest-risk subsystems
  5. Compliance Standard: Swap ISO 26262 for your applicable standard

Questions?​

This sample project demonstrates NirmIQ's capabilities for automotive safety-critical systems. Use it as a template for your own ISO 26262 projects, or explore the other sample projects for different industry domains.