Shut-Down Relay Board

Project Overview

The Shut-Down Relay Board is a critical safety component designed for the USC Formula Electric racing vehicle. This custom 4-relay PCB is responsible for isolating the high-voltage accumulator during fault conditions, ensuring the safety of both the vehicle and its operators. The system was developed to respond to multiple fault conditions including Brake System Plausibility, BMS (Battery Management System), IMD (Isolation Monitoring Device), and Inverter Precharge faults.

As the lead designer and firmware developer, I was responsible for the complete development lifecycle, from initial design through testing and validation. The system leverages the STM32's capabilities for robust and reliable operation in the demanding environment of a Formula Electric vehicle.

Technical Details

Key Features:

• 4-Relay Architecture: Designed to handle multiple high-voltage isolation scenarios
• Multi-Fault Response: Configurable response to various fault conditions including Brake System Plausibility, BMS, IMD, and Inverter Precharge faults
• High-Speed Response: Optimized for minimal latency in critical safety scenarios
• Robust Protection: Integrated MOSFET gate protection for enhanced reliability

Technical Implementation:

• Custom Firmware: Developed in C for the STM32 microcontroller family
• Schematic Design: Created using KiCad with emphasis on signal integrity and noise immunity
• Hardware Validation: Comprehensive testing using oscilloscopes and debug tools
• Fault Simulation: Verified performance under various fault conditions

Development Process

Design Phase:

• Conducted requirements analysis based on Formula Electric competition rules
• Designed schematic and PCB layout in KiCad with focus on reliability and safety
• Selected components based on automotive-grade requirements and availability

Firmware Development:

• Developed custom firmware in C for the PIC12 microcontroller
• Implemented fault detection and response algorithms
• Added MOSFET gate protection to prevent damage during switching
• Optimized code for minimal response time

Testing & Validation:

• Performed schematic capture and hardware bring-up
• Conducted oscilloscope and debug testing
• Validated performance under various fault conditions
• Ensured compliance with Formula Electric safety standards

Results & Impact

• Successfully designed and tested a reliable shutdown system for the Formula Electric vehicle
• Achieved fast, reliable shutdown response in safety-critical scenarios
• Enhanced vehicle safety through robust fault detection and response
• Documented design and testing procedures for future team members

Skills Developed