7.5HP Three Phase Motor Conversion

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Senior Member

Joined: 04/01/2008
Location: Albania
Posts: 510
Posted: 07:22am 24 Sep 2008      

  oztules said  If this scheme works well for you I am happy to take the accolades.... if you get run down by a high speed magnet fleeing the scene....

... then I'll blame Dinges ?

Good point though, that method should aid immensely when mounting the magnets in your case. Yes, wrestling those bastards in place isn't my idea of fun either. 36 of them on my 10 hp rotor... I was genuinely fearful when I started installing them. Turned out to go better than I expected, but mostly due to the new, full-steel rotor; once the magnet gets close enough to the rotor it attracts itself and stays perfectly put when on it. In your case only half the surface under a magnet is steel, so things may get a little harder... Providing for some excitement and the invention of some new swear words...

Interesting story, Steven. I'm surprized using just 2 magnets per pole, offset by half a slot (I assume that's what you did) is actually enough to nearly eliminate cogging; I would expect it to take at least 3-4 magnets per row, skewed in smaller steps, for it to work properly. I once made a tiny conversion that used just two round magnets per pole, skewed 'to the rules of the book', i.e. by half a slot, but which still cogged slightly. Your results are promising nonetheless.

  Oztules said  I am a bit non-plussed with the FEMM simulation. The flux lines are just not what I would expect to see.

Oztules, I think he's converting it as 4 pole, using 3 rows of magnets per pole. That way he can avoid rewinding. As a 4 pole the magnetic flux lines make sense.

If it were mine I think I'd have gone with a 12 pole configuration, but that would have been a lot more work as it requires a rewinding.

Looking forward to your updates, Steven, and will be especially interested to see if the real results come close to your calculated values (using the mathematical model you have developed).

Peter.Edited by Dinges 2008-09-25