I designed a precharge controller PCB that manages the inverter’s precharge sequence while keeping LV and HV domains isolated. The board can drive HV+ and HV− contactors, includes an onboard precharge relay and resistor, and provides a clean option to control an external precharge relay when needed. The onboard voltage sensor lets us capture inverter voltage to monitor and ensure a succesful precharge. An STM32 handles timing, sensing, and relay control, and visible LEDs make state and fault checks fast on the bench.
Features:
● STM32 microcontroller for handling precharge logic and voltage data collection
● Galvanic isolation between LV and HV paths
● Smart eFuse for inrush limiting, overcurrent protection, and status reporting
● Power & Data Isolation between LV and HV sections
● Onboard precharge relay and resistor with external relay interface
● Local step-down LDO for stable logic and sensor rails
● Via-stitched ground planes to reduce noise and EMI
● Clearly labeled test points and high-visibility debug LEDs
Bryan Lew | Electrical Engineering Student 