Multitooth motor winding idea

[liveforphysics]

If you wanted to improve motor torque per unit of motor weight, you would do the opposite and double the number of teeth and double the number of magnets.

Then that also doubles the amount of switching fields back and forth and doesn't that increase iron losses? I understood that less stator teeth was better for reducing iron losses than more teeth.

I'm with Punx0r on this one...too much conflicting information!

You make your power by flipping the field in the iron relative to the magnets. The more often you flip the field the more power you're making for a given mass of iron, as well as heat of core loss, but using your core is why you're carrying that lump of iron.

Right...that's what I understood too. So then which is better or perhaps that's not quite right. There's a balance to be had between flipping fields and iron losses due to flipping fields.

Large tooth count motors such as hubs have far more flipping feilds than say a C80100 outrunner. A 6kw hub is going to have far shorter stator teeth than the C80100 outrunner. Also, the hub is going to have many more teeth than the C80100. It would seem logical therefore that the hub motor will very likely be less efficient than the outrunner for no other reason than the iron losses from many more flipping feilds. Also, the C80100 will have long narrow stator teeth while the hub probably has more squarish teeth. This too is an advantage for the outrunner. It would seem that motors with long skinny stator teeth and a low tooth count are the best of all worlds. On one hand you maximize the torque bearing portion of each wind and on the other you minimize the iron losses. Then I have to ask...what is categorically a "low tooth count"? There has to be a balance here between iron loss and tooth count.

Did I get anything wrong here? Did I make sense?

What is the best balance?

The best balance for conventional affordable silicon stator lamination material is +-1.5T field flips 700-1kHz commutation freq (this is unrelated to PWM freq it uses for current control during the commutation pulse). 50/50 Cobalt/Iron laminations can flip about +-2T up to 1.3kHz commutation freq, and new CVD Silicon super-saturated lamination material is the highest continuous power density stator material Kg per Kg due to 2.5kHz at 1.5T being possible for practical budgeting projects (a single hubmotor's stator cost would be a few grand, generally about double-triple HyperCo50 lamination material).

 

[Buk___]

It makes sense of the train over-head cables, but I'm not sure where car wiring looms come into it, as AFAIK they, like most electric wire (and magnet wire) use pure copper!

There can be a weight (and cost) advantage to using a lower conductivity but overall lighter material like aluminium but car wiring is usually restricted by space as much as anything as modern cars have so many electrical systems the wiring loom gets bulky quickly.

Indeed. It was the reference to weight saving in cars that caught my eye.

The trade-off of conductivity for mechanical strength in overhead catenery makes sense, but it is hard to see how the increased strength would result in a weight saving in car looms.

The density figures I found list 0.321 lbs/Cu.In for CMG1 & 0.321-0.323 lbs/Cu.In for Cu-MTP, so it isn't even notably lighter. Somewhat confusing.

 

[ElectricGod]

The best balance for conventional affordable silicon stator lamination material is +-1.5T field flips 700-1kHz commutation freq (this is unrelated to PWM freq it uses for current control during the commutation pulse). 50/50 Cobalt/Iron laminations can flip about +-2T up to 1.3kHz commutation freq, and new CVD Silicon super-saturated lamination material is the highest continuous power density stator material Kg per Kg due to 2.5kHz at 1.5T being possible for practical budgeting projects (a single hubmotor's stator cost would be a few grand, generally about double-triple HyperCo50 lamination material).

Thanks for posting this...now to figure out what that means in an actual motor!