Some drawings for the 2hp conversion

[Sillyboy]

I've been planning and studying the conversion further. At the same time learning to use cad.

Here's what i've managed to produce.

I am going to use round magnets with 10 mm thick with diameter 20mm. Totally 40 pieces.

According to Zubbly's thumb rule this should be enough to get:

Magnets: 40*pi*100*10 = 125.7 cubic cm

Power:  150W/cubic inch = 9W/cubic cm

Power 9*125.7 = about 1150 W

This should be enough i think for a 2 hp conversion....

That size of mags should fit to the turned down rotor with diam 64 mm.

Filing flats under the mags should give me enough air gap to the stator.

Last i managed to determine the hopefully right skewing angle for the mags tobe 5 degrees.

 

I would be happy to hear your informative comments again.

Anyone have idea why my QCAD prints too small size images....??

Scaling etc...should be ok.

Ubuntu 7.10 + Qcad + brother DCP-330C

[dinges]

Hello Sillyboy,

I did a quick calculation checking your skew-angle (some figures were hard to read in the drawings, very small print), but I think your rotor length is 105 mm, the magnets are 20 mm dia and the outside diameter of the rotor is 87.5 mm. If this is correct then your skew angle should be 4.37 deg (see this image for the calculation: http://www.anotherpower.com/gallery/decogging/figure_27) I am using a slightly different variant of Zubbly's rule which should yield less cog. But I expect that the 'simple' rule of skew by one slot will work pretty well too, as you have 5 magnets per row, not 2 or 3 (in which case you NEED to make a correction). However, as it's just as much effort to skew by 4.37 deg. as by 5 deg, why not do it the proper way ?

Only worry I have is that part of the magnets will be outside of the stator and that this may interfere with the decogging. I.e. it may cog a little bit because of this.

I doubt it's really much of an issue in practice though. A very slight cog won't hamper performance much.

Looking forward to the rest of your project,

Peter.