Custom BLDC Motor & DSP-Based Control System

What We Built

Full-stack BLDC motor project: hand-wound stator, 3-phase inverter hardware, and open-loop SPWM firmware on a TI DSP, built from scratch by a 4-person team.

Motor

• Hand-wound 9-pole stator with 6-magnet (3 pole-pair) rotor
• Evaluated startup torque, rotor inertia, and thermal current limits before writing any firmware
• Rotor magnets chase the rotating magnetic field. Commutation handled entirely by the inverter + DSP, no brushes

Firmware

• Open-loop SPWM on a TI TMS320F28377D dual-core DSP
• Generates 6 PWM channels at a configurable carrier frequency
• Dead-time insertion prevents shoot-through; startup frequency ramp builds back-EMF before reaching target speed
• Debugged over isolated JTAG in Code Composer Studio

Hardware Revisions

• Rev 1: Bootstrap cap undersized, gate undervoltage lockout at low duty cycles
• Rev 2: Insufficient dead-time margin, MOSFET shoot-through at higher switching frequencies
• Rev 3: Coil overheating under load, reduced duty cycle ceiling and improved PCB thermal relief

Key Debug

Stall and oscillation fault traced to a pole-pair mismatch. Firmware assumed 4 pole-pairs, motor has 3. One constant change, stable rotation restored.

Next Steps

• Hall-effect sensors for real-time rotor position
• Space Vector PWM (SVPWM) for better DC bus utilization
• Closed-loop Field Oriented Control (FOC) for true torque control