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Re: [EVDL] 9" adv Aluminum feild coil housing ?

Hi Jeff,

I don't see what this SEMA motor has to do with the
subject. In fact, I think it uses back iron. Just no
armature steel. Like a moving coil motor, except the
coils are stationary and the field rotates. Like
brushless DC motors. But the field, PM, looks like it
is attached to plates, probably steel.

I have kept an eye on this motor off and on for a
while. I found it interesting. This guy claims it is
so new, but it looks just like the drive motor on my
Sanyo turntable bought in 1973. Great little motor.
No cogging. Great speed regulation, 33.3 RPM. Flower
petal shaped coils on the stator with no slots or
teeth and a rotor with magnets. Must be a whopping
1/100 hp.

And look at the large SEMA motor. 32 inch diameter.
650 pounds. 174 hp. What's so great about that?

--- Jeff Shanab <[email protected]> wrote:

> You can't get anything for free. But take a look for
> SEMA motor. IIRC,
> this stands for Segmented ElectroMagnetic Array.
> I believe they eliminate the back iron by useing air
> coils. You can
> create a greater magnetic field than a saturated
> core would allow with
> air coils by pushing more current through.

As iron saturates, the relative permability approaches
unity, but never drops below unity. Therefore, having
a material which saturates in the core will never
present a reluctance greater than an air core.


Jeff M

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