Stator width vs motor inductance

[zombiess]

I was wondering what kind of effect stator width has on motor inductance if the # of winds stays the same.

 

[liveforphysics]

Anything that increases the diameter of the loop, puts more magnetically permeable material in that loop, or makes more laps around the loop will all increase inductance.

So, if you took a motor, still wound with the same number of turns, and magically added lam's to make the stator thicker, it would increase in inductance. HOWEVER! It's KV will drop by the same amount that it was widened. So, if you widen the stator by say 50% and then decrease the turn-count by 50% to get your KV back where you wanted it, then you end up increasing both loop area and core permeability by 50% each, yet your 50% decrease in turns varies at the square of inductance, so it looks like you end up exactly where you started to begin with if you widen a motor and keep KV the same. If you just widen a motor you will increase inductance (and decrease power potential unless you increases voltage by the same amount you widened the stator by, then you get it back).

 

[zombiess]

Thanks Luke. I was wondering how a 2 turn Hubzilla might perform and if it would be a controller killer. I need to get an inductance meter and check the inductance on my 9.3kV motor. I believe the inductance of a 2 turn would be 0.25 of what ever the 4 turn motor is.

 

[dogman dan]

You just explained something I've sort of wondered about for years.

Why is the winding count for about the same speed so different between a 9c and a 5300. Both about the same diameter, so the only noticeable difference is the stator width.

With your explanation, it now makes sense why to this dumbshit.

 

[zombiess]

So I've been told that a Crystalyte 5304 has about 256uH of inductance, it's stator width is say 32mm from what I've read. A 5302 would then have 64uH of inductance aka controller killer. I've heard with 24 FET controllers you really want to keep the inductance above 80uH to keep them alive and run a small wheel so BEMF kicks in faster.

Would it then be logical to estimate a 2 turn Hubzilla would be 100uH using the following?

50mm / 32mm = 156% mm wider
5302 is 64 uH inductance so 64uH * 156% would be 100uH

 

[thepronghorn]

Anything that increases the diameter of the loop, puts more magnetically permeable material in that loop, or makes more laps around the loop will all increase inductance.

Since the stator laminations are not skewed on the hubzilla, but they are on the 5302, and increasing stator width does not add end turns , I think your inductance would be a little less than 100 uH because the diameter of the loop would not increase by the same proportions as the stator length.

 

[zombiess]

Anything that increases the diameter of the loop, puts more magnetically permeable material in that loop, or makes more laps around the loop will all increase inductance.

Since the stator laminations are not skewed on the hubzilla, but they are on the 5302, and increasing stator width does not add end turns , I think your inductance would be a little less than 100 uH because the diameter of the loop would not increase by the same proportions as the stator length.

You are probably right. The magnetic properties are different as well because the stator laminations are most likely different material.

 

[John in CR]

The X5 wouldn't be a good place to start to back into your Cromotor inductance, because it's a completely different stator type with a much lower pole and tooth count. I think Arlo1 has the numbers on one of the HX stators, which I think has the same pole and tooth count, just a 35mm stator.

 

[zombiess]

The X5 wouldn't be a good place to start to back into your Cromotor inductance, because it's a completely different stator type with a much lower pole and tooth count. I think Arlo1 has the numbers on one of the HX stators, which I think has the same pole and tooth count, just a 35mm stator.

Thanks John, I'll ask him about those unless those were the numbers he was quoting me he measured when we were talking (who I got the original number from in this thread).

Just found a post by andreym who measured it at around 275uH which would put a 2 turn around 69uH