Leafmotor

How to build a pretty basic dual brushless motor controller? I’m going to focus on the power section in this post, and as soon as I have time I’ll discuss the code/FroBoard side of things in another post. I got started on the power section last night after a copious amount of coffee, and wrapped it up this morning- it’s a pretty simple build if you’re used to building stuff on perf board. I firmly believe that the best way to learn how something works is to build it yourself- that’s how I learned about electric cars, and brushless motor control is no exception. So if you want to learn how brushless motor controllers work, build one! A controller this size is a great place to start if you’re just getting involved in brushless motor control- I would definitely recommend starting out with something like this if you plan on building a car-sized controller. In fact, my first brushless controller was essentially half of this controller. It’s good up to around 24 volts and 1 or 2 amps per motor, but with proper heatsinking it could probably take a bit more current.

This post is written with the electronics hobbyist/motor enthusiast in mind. It’s also turned out to be a bit longer than expected; ah well. I’ll try harder next time! Most of this won’t make any sense if you don’t have a rough understanding of what brushless motors are and how they work- if you’re in that group, no worries. There are lots of great sites out there explaining those details;  unfortunately, I don’t have the space to go through it here. I’m really just hoping to take a little bit of the mystery out of brushless motor control and show that it isn’t all the black magic it can seem like- hopefully it helps a few hobbyists out there get a little further.

This controller is currently driven by two FroBoards, which is definitely more processing power than is really needed- it’s cool because it leaves room to read encoders, do serial stuff, and anything else you want to do in addition to running the motors. I’m running a whole robot off of these two FroBoards- usually, the motor controller is a separate unit, and another processor is used to handle the higher level decisions. Right now, for instance, I have a serial routine set up that lets me use a terminal emulator (MacWise in my case) to drive the robot around using the number pad on my keyboard, and there is still tons of room for add-ons. With a storebought setup, this would probably take two separate motor controllers and a processor to control them. So anyway, that’s pretty cool. That said, this power section could just as easily be driven off of a different processor or board; it isn’t specific to the FroBoard.

Likewise, it would be really easy to build a single motor controller for use with one processor or FroBoard in this style. It would just be a matter of getting rid of three of the half bridges. Anyway, without much ado, here’s a schematic for you all!