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Old Mar 08, 2006, 07:52 PM
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Jesper Frickmann
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Question

ESC for a single phase sensored BL motor


I guess a single phase sensored brushless motor is just a brushed motor with "electronic brushes" in the form of a sensor and a controller.

As far as I can figure out, such a motor ought to be better than the normal three phase BL motor because:
1. All stator poles are used all the time, instead of just 2/3 at a time.
2. All stator poles and magnets are in phase, as oppposed to the two phases being used at a time being 120 electric degrees apart in a normal three phase BL motor.
3. The number of stator poles and magnets are the same, they are always "right on", as opposed to e.g. 12 poles and 14 or 16 magnets.

Am I right? If not, where did I get it wrong?

I think it could be fun to build a GoBrushless.com 12-stator motor of each kind and compare their performance, to see if I am right.

But I can't do it without a controller!! Does anyone know if there is an ESC (or a kit) for sale for such a single phase sensored motor?

Thanks,
Jesper
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Old Mar 09, 2006, 02:27 AM
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I din't think there is anyway to work out the direction of rotation on a single phase motor, or even if there is, no way to get it to run forwards if it starts backwards.

All single phase motors normally have a 'starting phase' with a capacitor...to give phase lead.

3 phase motors are the norm for a very god reason. They work. And they work better than almost anything else.
Old Mar 09, 2006, 06:45 AM
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Quote:
Originally Posted by vintage1
I din't think there is anyway to work out the direction of rotation on a single phase motor, or even if there is, no way to get it to run forwards if it starts backwards.
That's why it needs a sensor! With a sensor, it will commutate just like a plain old brushed motor.

Jesper
Old Mar 09, 2006, 07:05 AM
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Quote:
Originally Posted by jfrickmann
That's why it needs a sensor! With a sensor, it will commutate just like a plain old brushed motor.

Jesper
But a brushed motor is 3 phase...
Old Mar 09, 2006, 11:54 AM
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Please have a look at this article. I basically would like to build an implementation of the "plain" DC motor with the following two changes.
1. The mechanical commutator (brushes) is replaced by an electronic commutator based on a Hall sensor and FETs.
2. Instead of a two-pole "inrunner" I will try a 12-pole outrunner.

Best regards,
Jesper
Old Mar 09, 2006, 12:27 PM
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Quote:
Originally Posted by jfrickmann
Please have a look at this article. I basically would like to build an implementation of the "plain" DC motor with the following two changes.
1. The mechanical commutator (brushes) is replaced by an electronic commutator based on a Hall sensor and FETs.
2. Instead of a two-pole "inrunner" I will try a 12-pole outrunner.

Best regards,
Jesper
If you want single phase, you should build a 3 pole / 2 slot motor wound Aa. The Kv would be extremely high so it would be a very high rpm motor.

If you want a 12 pole outrunner w/ 16 poles, it can't be single phase.
Old Mar 09, 2006, 05:53 PM
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I was actually thinking of a 12 pole motor with 12 magnets. It will be similar in principle to the brushed DC motor, except it alternates 12 instead of 2 times per revolution.

Jesper
Old Mar 09, 2006, 07:37 PM
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It might work. For sure, you will have to flick the prop to get it going, but that would be kind of cool. Sort of like starting a cox .049.

I wound one like this a while ago, but don't have an ESC to drive it. I think one of us will have to make one.
Old Mar 09, 2006, 08:18 PM
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Funny, I was thinking that with the Cox too.

And yep, the ESC is definitely the problem! I put together a few PCBs as a teenager, but that's completely different from designing it. Unfortunately, I chose chemistry over electric engineering in school, so although I know the basics of electric circuits, I am very far away from being able to design it.

Does anyone know of a DIY ESC with a sensor?


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