AKM-75sx and VESC - motor poles count?

[braunschweiger]

I am in the process of building a lightweight pedelec solution while trying to avoid vendor lock-ins. The AKM-75sx (201rpm nominal) is setup in 28" front wheel. For controller I want to use an VESC (with some logic from arduino). This combination of motor and VESC surely has been run before?

For VESC I have both a Maytech superfoc6.8 and a makerX-miniFOCplus at hand.

Now the VESC configuration requests the motor poles count for this sensored motor. This should be known but aikema did not respond and I could not find this info in this forum or google search.

 

[Chalo]

Now the VESC configuration requests the motor poles count for this sensored motor. This should be known but aikema did not respond and I could not find this info in this forum or google search.

In this situation, first I start with a rough guess at poles per revolution, like 100 for a geared hub motor. I run the thing wide open throttle and get a steady RPM number using either an optical tachometer or comparing against beats-per-minute videos on YouTube. The display (if I have one) will tell me what road speed it thinks it's going. Then I use 4QD's road speed calculator to correlate wheel RPM to road speed, and I make corrections to the poles per revolution parameter until the display matches the calculated road speed.

I don't know whether VESC outputs a real time speed or RPM number. I only use controllers that are pretty much ready to run out of the box.

 

[amberwolf]

If you are patient and careful, you may be able to count the poles by manually rotating the wheel backwards very slowly, feeling for each "click" (not the right word, maybe "detent" or "resistance"), from the point the valve stem is at the top-dead-center till it's back at that point.

Alternately, if it has motor halls sensors, you can use a multimeter to count the number of itmes the voltage on one of them changes from around zero to around 5v, in one very slow manual wheel rotation.

 

[derekderek]

i believe most geared motors are 20 poles and most common ratio is 5 to 1. and that is where the default 100 comes from you wanna be sure? i bet your motor gears need checked-cleaned-greased anyway. count the teeth on big outer gear (asteroid belt gear?) and divide by teeth on sun gear.

 

[chuyskywalker]

Open it up and count them.