The past

A project log for Ø32 BLDC Controller

Miniature closed-loop controller for brushless DC motors

christopher-xuChristopher Xu 01/13/2023 at 20:170 Comments

This project started when I tried to make a jumping robot. It jumped, but the servo seemed weak for its weight. I looked into brushless motors, but existing drone and car ESCs did not have the positional accuracy at low speeds and the more complex sensored motor drivers like the Odrive were too bulky, and also expensive. So, I tried to make my very first PCBs:

The motor driver board is the small one on the right, designed to fit behind the red motor. The larger board serves as the main controller, and this main board can control up to two driver boards. I based my design on the RAA227063 gate driver IC, and the PWM commands must be sent from the Teensy 4.0 on the main board. This worked, but only for a moment. 

With any load, one of the high side mosfets would be burn out, ending up with the gate shorted to drain. I replaced the mosfet 2 times, with the same failure. After some crude probing I believe this was the result of ringing on the gate, because I didn't put a resistor between the driver and the gate, and the trace was probably not routed optimally. Next version, I'm adding a gate resistor and making it a 4-layer board, hoping that the extra ground planes will decrease parasitic inductance. There will also be RC snubbers on the output in case.