3 phase or 6 phase motor?

macribs · Aug 2, 2014

I was chatting about e-bikes, cromotor etc with a friend. And he asked why run it at 3 phase and why not 6 phases with 2 controllers?

I never even taught about that before, and didn't have a clear view of what is actually 3 phase so I didn't know what to respond and soon forgot about it. I am currently still not sure what is possible to achieve but after watching a youtube vid it seems 6 phase would double your power.

Is there any advantages to run a 3 phase motor as 6 phases? Less load on the controller probably as one can use 2 controllers. Will that allow for more voltage then what a normal controller can handle?

Will wire it up to use 6 phases give any benefits at all over 3 phases?

Blue ones opposite each other 3 phase and same for red makes 6 phase?
Or will 6 phase make the motor run with more rpm and torque?

docnjoj · Aug 3, 2014

Falco motors states that their's is a 5 phase. Says it makes more torque and is smoother. I don't know but the old Tidalforce ones were super quality and powerful.
otherDoc

Lebowski · Aug 3, 2014

I've tried it and been succesfull at running a 6-phase motor with 2 controllers. There can be several reasons to do this:

- If you have a motor like John where you have 2 3-phase motor with a small 30 degree phase difference, then you will be more
efficient and get more torque than if you would wind it as a single 3-phase. However, you're talking mostly about a theoretical
advantage as it's only a few %.

- You could go to higher rpm for the same voltage by halving the amount of windings each controller sees.

- two 6-FETs will be more reliable than one 12-FET. This because a 6 FET has a lower inductance output stage than a 12 FET,
making the life of the FETs easier. Plus, if one FET blows you can shutdown that controller and keep riding with the other one.

- A 5 phase may be smoother if you use block commutation, when you have sine wave controllers there's no advantage (w.r.t. smoothness)
over a 3-phase. I think you may actually be at a disadvantage as typically the 3rd order harmonic is higher than the 5th...

running 6-phase, 2 3-phase with 30 degree offset:
http://endless-sphere.com/forums/viewtopic.php?f=30&t=36602&start=875#p910484
running 2 3-phase, all on the same teeth effectively giving higher kv:
http://endless-sphere.com/forums/viewtopic.php?f=30&t=36602&start=875#p910989

Kingfish · Aug 3, 2014

macribs said:

The short answer is that the graphic is a super simple 3-phase motor. A 6-phase will have double the amount of teeth although connected independently of the 3-phase. It's possible to use 2 controllers, although there are some that employ 6-phase natively. The reason for 3- verses 6-phase has a lot to do with having more precise control under load, or to deliver twice more power when limited by current-carrying conductors. In addition, for motors having many teeth, using 6-phase provides an opportunity to further refine the shape of applied power. It's mainly for industrial applications.

As for ebikes, it's overkill for all but the most powerful motors applications such as strong mopeds and eMotos. Search the marketplace: John in CR sells and/or has been using them.

There is a ton of good reading material out there if you wish to take the time.

>> 6 phase hub motor?

Speaking in polyphase, KF

Drunkskunk · Aug 3, 2014

5 phase is interesting for a few reasons, mostly because it runs smooth and quiet at low rpm. But If you've ever run an old Clyte 40X, you would have to re-define smooth and quiet, even though it's 3 phase. There are other ways to make a motor run smooth, or be quiet. Some of it is just better motor design, some of it is in controller options. 6 Phase exist, but they're basically just a double motor in a single shell. That keeps the costs down, but doesn't offer a tangible performance advantage except in special cases.

But there is no advantage to more phases in a properly designed motor. The highest efficient motor commercially available is the Csiro. At 98% efficiency, it's approaching the limit of wire efficiency in conducting.
It's 3 phase.

macribs · Aug 3, 2014

Thx all, been trying to read up and with the help from you all I get a better understanding.
So it is mostly an academic exercise to use 6 phases for our needs. Good then I can go back to read more important stuff.

Nothing I need to worry me head with as of any time soon, and that is great for there is almost an information overflow in my brain now.

This is me on a normal day:

This is me reading 6 phase theory:

John in CR · Aug 3, 2014

There's more than just a theoretical advantage. While it may be true that with a sine wave controller the common 3 phase motors can approach how quiet my 6 phase motors are with typical cheap controllers, sine wave controllers are still expensive. 2 controllers are typically cheaper than 1 capable of double the power once you get into the higher power range. That's because extreme current gets harder to pull off reliably with 3 phase motors without hitting the pocketbook too hard. Another benefit is that in sensorless operation more phases makes startup smoother.

I doubt you can take a motor designed as a 3 phase motor and wind it as 6, 9 or more phases and see much benefit other than improved sensorless operation. That doesn't mean a properly designed 6 phase motor doesn't have real advantages over 3 phase. Bringing up a specialty motor that costs over $10,000 , weighs 14.5kg, and puts out a paltry 1800W to achieve it's extreme efficiency, is irrelevant to this discussion. At least wrt hubmotors, the best reasonably priced hubmotors are 6 phase, and others really don't even come close, and the proof is in the performance. Tell the 3 phase hubbie lovers to call me when they break 100mph. I have the old model Xlyte 4xx and 5xxx motors, and my 6 phase motors are more quiet, and while they'd be lucky to hit mid 80's in efficiency, the 6 phase motor I ride every day has a peak efficiency of over 94%, though that efficiency advantage is likely to be more in the design and materials than in being 6 phase.

macribs · Aug 4, 2014

@John in Cr

I've found your thread about your 6 phase and what you achieved with that motor is amazing. I am looking forward to see that thing with 2 wd

macribs · Sep 27, 2014

John in CR said:
There's more than just a theoretical advantage. While it may be true that with a sine wave controller the common 3 phase motors can approach how quiet my 6 phase motors are with typical cheap controllers, sine wave controllers are still expensive. 2 controllers are typically cheaper than 1 capable of double the power once you get into the higher power range. That's because extreme current gets harder to pull off reliably with 3 phase motors without hitting the pocketbook too hard. Another benefit is that in sensorless operation more phases makes startup smoother.

I doubt you can take a motor designed as a 3 phase motor and wind it as 6, 9 or more phases and see much benefit other than improved sensorless operation. That doesn't mean a properly designed 6 phase motor doesn't have real advantages over 3 phase. Bringing up a specialty motor that costs over $10,000 , weighs 14.5kg, and puts out a paltry 1800W to achieve it's extreme efficiency, is irrelevant to this discussion. At least wrt hubmotors, the best reasonably priced hubmotors are 6 phase, and others really don't even come close, and the proof is in the performance. Tell the 3 phase hubbie lovers to call me when they break 100mph. I have the old model Xlyte 4xx and 5xxx motors, and my 6 phase motors are more quiet, and while they'd be lucky to hit mid 80's in efficiency, the 6 phase motor I ride every day has a peak efficiency of over 94%, though that efficiency advantage is likely to be more in the design and materials than in being 6 phase.

I continue to stumble upon references to 6 phase motors on ES. This time it was the Colossus RC outrunner thread. People where asking for a tailor made version 6 phase.

My understanding of RC motors are that they commonly run without sensors. Would there be any advantages to run a RC as 6 phase? I mean those motors has crazy power to weight/size ratio. But it does seem like they can be hard on controllers. From what I read between the lines the Colossus was discontinued because of controller issues. Well that's how I read it, might be wrong here. Anyway lets just use the Colossus as an example below as most of know that motor, or have heard of it.

So if Colossus was winded as a 6 phase motor, customers could split load on two controllers. Any spikes or heavy draw of power during acceleration @ WOT would at least be easier on each controller. But if we take things even further, adding Hall sensors to such a 6 phase RC motor, would that in any way help for durability, power delivery, smoothness or noise level? I mean adding Hall's would enable the use of sine waves. How could if possible a couple of sine waves contribute in a positive manner to a 6 phase RC motor with added Hall's?

Or should a 6 phase in fact run with no sensors? What you think John? You have been doing crazy speed with a 6 phase for a while now. It runs with no sensors, right? Would your experiences translate to RC outrunners as well or only for hubs in wheel?

3 phase or 6 phase motor?

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docnjoj

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John in CR

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