More than3 phases

[larsb]

six phase driving like in the hubmonsters will cancel out some of the harmonics that don't contribute to torque. These drive eddy losses so efficiency will be slightly higher. somewhere in my saved science papers i have some data on this, can try to find it.
Also it will be fault tolerant, one dead controller doesn't mean you do the walk of shame.

The distributed winding like in the Astro motors has the same effect on harmonics, some will be cancelled and winding factor can be higher, even 1 is possible with distributed winding so you get full torque output possible. You pay for this with increased copper losses as all the transits get longer..

 

[macribs]

Please see if you can find that thread about power gains from 6 phases vs 3 phases. If there is something to this from the perspective of the motor, I'd like to know about it.

Yeah I will do some searches. Sadly I computer failure revoked all my bookmarks so I can't find back to it via bookmarks. I will take some time tonight to search the forum. Iirc that thread is the only one here on ES regarding 6 phase motors where someone actually put some real math into the discussion. There have been a few of these threads, 6 phases vs 3 phases over the years, but I have never seen any hard evidences in either direction, except that one thread. Maybe someone else remember it and can find back to it based on this?

What would be amazing would be to see a handful of motors wounded in 3 phase and 6 phase and got all those on a dyno.

This topic is so toxic and hard to grasp I have even often asked electrical engineers I met about this, without any clear cut answer. Electrical engineers seems to agree there is theoretical benefits, but of course an engineer is trained to look at a problem in various ways. So they've given some vage answers. It depends on this and that, possible etc.

If I ever get me a dyno I know such a test would be one of the first things I would do.

 

[kenkad]

The previous discussion was titled

"6 phase motors - are they all that?"

in late 2014

 

[macribs]

The previous discussion was titled

"6 phase motors - are they all that?"

I looked at that thread just briefly now, but I don't think it was that thread. I am not sure. I will take my time and read it all just to be sure.

I saw a few post by you in that thread where you mention a 6 phase motor is running controllers as master&slave. Afaik the real world is much easier. Two sets of halls in a 6 phase motors gives each controller the "waypoint" for their motor. So the two controllers will in fact "auto sync"and always be "in tune", and if one controller dies you can still run that motor as a 3 phase motor rather then as 2x3 phase motor. Of course my lack of a technical education might play a trick on me here, maybe there is more to this redundancy issue then I can wrap my small brain around. But hey, that is why threads like this are so great. So that we can learn from each other. Even unschooled ones like me.

I will keep reading and searching to see if we can discover the math behind the 6 phase benefits.

 

[ElectricGod]

If I ever get me a dyno I know such a test would be one of the first things I would do.

Making a dyno is not that hard. All you really need is another brushless motor and a way to load its windings. I ran into some youtube videos a while back where a guy was testing an outrunner loaded by an identical outrunner.

I considered making one of these but like many things, never got around to it.
An exercise bike has adjustable loading. It has to work pretty reliably or no one would use an exercise bike. I think I could work out without too much trouble exactly how much load is being made with a torque sensor. I've seen them in a special chain roller and in bottom bracket hubs for bikes for measuring human wattage. The cost would be pretty low for something like this and easy to implement.

A tool like this would definitely provide real world results about 3 phase vs 6 phase.

 

[macribs]

Yes it is not that it is impossible to build, it's more like life you know. There is this thing called life that is nagging you constantly everyday. Do this and that. Remember to and don't forget. There are family, friends, work, riding e-bikes, motorcycles, charging bikes and motorcycles and maintenance. Cut the lawn, rebuild this and weld that, paint the fences, chop woods for the winter, then there is social events, beer drinking, occasional gigs with the band, etc etc. I can barely keep up as is. So I don't see a dyno in my life any time soon.

But if I get a chance to clone myself and bring that carbon copy to instant life, dyno is very high on my list

 

[billvon]

Dyno graphs show that you don't get a benefit from more phases. The real downside is that you have to design a custom controller around 4,5,6,7 phases..

The old EMS Tidalforce used 7 phases, I think. They called it the "wavecrest" system. I think it was a way to smooth out the torque without using a sinewave controller.

 

[ElectricGod]

Dyno graphs show that you don't get a benefit from more phases. The real downside is that you have to design a custom controller around 4,5,6,7 phases..

The old EMS Tidalforce used 7 phases, I think. They called it the "wavecrest" system. I think it was a way to smooth out the torque without using a sinewave controller.

As long as you stick to increments of 3, you don't need special controllers. Any BLDC controller will run a 6 phase motor. You just need 2 controllers.

I think smoothing out the power is probably the biggest gain you get in the motor.

Otherwise it's about using multiple cheap controllers instead of one expensive controller.

 

[ElectricGod]

Yes it is not that it is impossible to build, it's more like life you know. There is this thing called life that is nagging you constantly everyday. Do this and that. Remember to and don't forget. There are family, friends, work, riding e-bikes, motorcycles, charging bikes and motorcycles and maintenance. Cut the lawn, rebuild this and weld that, paint the fences, chop woods for the winter, then there is social events, beer drinking, occasional gigs with the band, etc etc. I can barely keep up as is. So I don't see a dyno in my life any time soon.

But if I get a chance to clone myself and bring that carbon copy to instant life, dyno is very high on my list

I have to agree! Who ever invented life and business...I just want to kill that guy. What a jerk. The temerity! To think I have to work a job and pay bills and fix stuff. Geez! That's just too much! I should be able to do what I want when I want and not care about how much it costs.

Maybe a clone is the right solution...a slave...do the work and BS stuff so I can go play in the garage! Don't bother me with anything other than food and drink! Don't you see I am doing important stuff here? =)

Same here...dyno...cool idea...building one...not likely.

 

[billvon]

As long as you stick to increments of 3, you don't need special controllers. Any BLDC controller will run a 6 phase motor. You just need 2 controllers.

The Tidalforce was not a multiple of 3, intentionally. They did it that way so that each winding would apply torque at a time that was not synchronous with any other winding applying torque, thus smoothing torque delivery even without a sinewave controller.

(BTW this was NOT a cheap controller; it was built into the hub on a very large, and very custom, PWB. Can't find a picture on line but it was worth seeing for the engineering alone.)

The Tidalforce bike later morphed into the EMS E+ bike with few changes. EMS folded as well.

 

[ElectricGod]

As long as you stick to increments of 3, you don't need special controllers. Any BLDC controller will run a 6 phase motor. You just need 2 controllers.

The Tidalforce was not a multiple of 3, intentionally. They did it that way so that each winding would apply torque at a time that was not synchronous with any other winding applying torque, thus smoothing torque delivery even without a sinewave controller.

(BTW this was NOT a cheap controller; it was built into the hub on a very large, and very custom, PWB. Can't find a picture on line but it was worth seeing for the engineering alone.)

The Tidalforce bike later morphed into the EMS E+ bike with few changes. EMS folded as well.

Thinking about this...
I was trying to imagine how you would get 6 phases or dual 3 phases to "fire" 30 degrees off from each other.
The more I thought about it realized that this happens automatically.
Each motor has it's own sets of halls and each motor has half of the stator teeth.
It is already "firing" 30 degrees off by default.
It's almost a mute point really in a motor with many magnet poles and many stator teeth.

If you think of the stator teeth and magnets like they are pistons in an engine, then...
At any moment in time, 120 degrees at a minimum is "firing" and that's wired delta.
In WYE it is 240 degrees since 2 phases are always active.
Thinking about the angles for 6 phases makes my brain hurt!

That 7 phase motor...did it fire a single phase at a time? That seems unlikely. Probably they had something like 5 out of 7 seven phases active at any moment in time.

Yeah! a 7 phase controller...NOT cheap!!!