Low speed control on sensorless BLDC motors with "reluctance sensing"?

Hey, I was reading an article from 2012 about driving sensorless BLDC motors using “reluctance sensing”. It claimed the tech could be used for positioning applications too. I’d love your opinions on this. Would this make ODrive better? Do we already use something like this?


Yes there is a technique to control “salient” brushless motors down to zero speed using High Frequency Injection, which is precisely what you are referring to. We do not have support for this yet, but it is in the roadmap, see here. It will be a fair while until we get there though. Unless someone in the community has a strong need or desire to make this and want to do it themselves; in that case I am happy to give my support at any time.

Cool! Glad to know the technical name for the technique.

Man, BLDC control is a whole different world from DC motor control. I’ve worked on DC control earlier, it will be fun to work on BLDC motors. They’re definitely worth the effort, considering their low cost. Even high end manufacturers like Maxon motors have much priced their BLDC motors much lower than DC.

I’d love to work on this, but I have too many projects on my hand at the moment. I’ll jump in when I can, @madcowswe

I’m ordering my ODrive board in 2 weeks!

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Awesome, you are welcome in either case ;D