bigmoose wrote:Thud, look back above at my post. I edited it... I found the design paper for the CISRO Motor!
Perhaps the strip coils would work for a slower speed motor?Miles wrote:Here's a model I made to a drawing of a coreless AF from Thud:
rhitee05 wrote:Here's the citation, for those with the interest and means:
Caricchi, F. et al., "Performance of Coreless-Winding Axial-Flux Permanent-Magnet Generator With Power Output at 400 Hz, 3000 r/min," IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 34, NO. 6, NOVEMBER/DECEMBER 1998, pp. 1263-1269.
rhitee05 wrote:For an ironless stator, apparently the optimum coil shape is actually a rhomboid. Pie-shaped coils aren't optimal because the straight runs on the top and bottom are useless copper that adds resistance but doesn't contribute to torque. They claim a rhomboid is the best compromise.
Therefore, disregarding the case of machines having a very large number of poles and, thereby, very short end windings, the use of trapezoidal coils negatively affects the value of torque produced per unit of , and this is undesirable for machine applications with high power ratings.
In fact, due to the inclined arrangement of the coil active sides, in rhomboidal coils, the end windings are greatly shortened, but with only a small reduction of the coil flux linkage if compared with the conventional trapezoidal-shape coils.
The geometry of rhomboidal coils is characterized by the inclination angle alpha and the ratio Kr between the inner radius and outer radius... With the
values of and related to an optimized design, it is found that the use of rhomboidal coils results in 25%Ã¢â‚¬â€œ30% reduction of winding resistance and 10%Ã¢â‚¬â€œ12% reduction of EMF, compared to trapezoidal coils.
Never heard of mandorla before, I had to google that. Seems like that shape would be wicked-hard to wind. Unless you're talking about lap winding - overlapping the phases? That's definitely a good idea, it would reduce the Kv of the motor and dramatically increase the copper fill in the stator.
Miles wrote:What I meant was something like a wide aspect-ratio ellipse.
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