I’m trying to get this motor running smoothly using its internal hall sensors: EzRun 1626
As far as I can tell the motor has 3 slots, 2 poles (1 pole pair) and three hall sensors which should provide a position resolution of 60°.
My question is - given the small number of slots, we would expect strong cogging every 120° for this motor, right? And this is what I’m experiencing in practise. I haven’t yet been able to get this motor to run smoothly at low speeds at all, even in open loop mode. It just jumps from slot to slot, like a stepper motor.
The only way I can concieve of this motor not having bad cogging is with an extremely high current of 20A+, which is what is supported by the Hobby ESC that comes with it.
However, I think driving it at 20A at low speed would certainly overheat the motor because it relies on spinning fast to cool down.
Keen for your thoughts on this. Have I been fooled by false advertising?
Try ramping the current up and down while turning slowly in open loop and see if it ever smooths out. I’ve generally found that there’s a sweet spot where cogging is minimum.
Unless the hall sensors are linear type, they only give full step resolution so there’s no way to get anything better for closed-loop position control. SmoothingSensor can help, but only while the motor is moving.
Hey, I would definitely call them up and ask them what they mean, exactly.
It may just be a difference in the definition of what you each consider as „low speed“.
Since this is a 6500KV motor I don’t imagine low speed means less than a few thousand RPM to them…
Perhaps this is a good use case for SmoothingSensor since I’m planning to operate the motor at 2000rpm+.
At that speed I imagine the hall sensor velocity readings will be very responsive, but the position readings less so. Does commutation work well with SmoothingSensor at these kinds of speeds? What’s the difference between using SmoothingSensor vs a longer low pass filter?
And I’ll fish around for a speed/current sweet spot. You may be right that 2000rpm and 20A is what they consider a slow speed for their application.
However, “zero cogging” is a strange statement to make for a motor that cogs like hell when I turn it by hand I will get in touch and ask for an explanation
In some ways, 3 slots and 2 poles seems like the absolute worst case scenario for a low cogging setup.
I wouldn’t be surprised if by no cogging they mean “smoothly rotates in a huge 120 deg region”. I have seen other people make the same mistake before. Rotating a motor by hand feels steppy, and some people equate “more steps” to “more cogginess” (and vice versa), whereas we know it’s actually the opposite.
I will get in touch and ask for an explanation 