Can you use permanent magnets...

Discussion in 'The Projects Forum' started by Boomer999, May 6, 2013.

  1. Boomer999

    Thread Starter New Member

    May 2, 2013
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    Can you use permanent magnets In an alternator Instead of electromagnets? And the poles/magnets are they staggered north south like a generator? I was going to build an 8 pole/magnet rotor. Was wondering if I would stager them North South. I think I do. But would just like to confirm it. My textbook is pretty good Delmar,s Standard Textbook of Electricity. But it seems to have left this info out. Help please.:)
     
  2. Ramussons

    Active Member

    May 3, 2013
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    Can you use permanent magnets In an alternator Instead of electromagnets?
    Yes you can. You may have constraints on Voltage Control, Overload Control, etc.

    And the poles/magnets are they staggered north south like a generator?
    Yes, they are.

    Ramesh
     
  3. strantor

    AAC Fanatic!

    Oct 3, 2010
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    The alternator has the variable rotor current so that the output voltage can be controlled even as the mechanical input RPM varies wildly. When you replace this variable control with permanent magnets, your output voltage will vary with input RPM. If you want constant voltage output, you will need constant input RPM.

    That is the theory part of the answer. The practical part - actually replacing the rotor winding with magnets - is something I can't answer. I've never tried or read about anyone else trying. It seems to me like it might be harder than it's worth. You may be better off to buy a permanent magnet motor to start.
     
  4. Wendy

    Moderator

    Mar 24, 2008
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    It is the difference between an alternator and a generator.

    Automotive topics, especially electrical, are not allowed on AAC. It is part of our terms of service. Are you thinking of actually doing something like this?
     
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    This post is not automotive, it is about making a motor from an alternator. Becides a strong ring magnet, a position sensor is needed, along with a pulsed DC drive ckt.
     
  6. wayneh

    Expert

    Sep 9, 2010
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    You don't need those complications to convert an alternator into a PMA. You just need to replace the former electromagnets (field windings) with permanent magnets.
     
  7. joeyd999

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    That would be called an induction motor.
     
  8. strantor

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    unless you replace the rotor windings with permanent magnets ;).
     
  9. joeyd999

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    Naturally.
     
  10. Boomer999

    Thread Starter New Member

    May 2, 2013
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    Yes I am building this. And it is for no application. I am just playing in my garage. And it it is not automotive i am just using the windings from an alternator. It's low budget. Experimenting and learning. Some of the questions I am asking is just to confirm what I was thinking.
     
  11. wayneh

    Expert

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    The DIY wind energy guys do this a lot. Look around and you'll find tons of tips and tricks. Wire gauges to use, favorite magnets and configurations, real world performance data, and so on.
     
  12. Boomer999

    Thread Starter New Member

    May 2, 2013
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    Thank you for all the info everybody.
     
  13. Boomer999

    Thread Starter New Member

    May 2, 2013
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  14. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Motorcyle alternators usually use a permanent magnet rotor and a single phase or 3 phase stator.

    You could use parts from a motorcycle alternator in your home made device.
     
  15. Boomer999

    Thread Starter New Member

    May 2, 2013
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    Did some research about the conversions for alternators for air turbines. They half the wire size and double the turns. Which can do one of two things for you. At the same rpm it creates double the voltage or you can half the rpm to get the original voltage. As well you can take the rivets out of the windings cores and bolt two together you do the same thing again. Double the voltage or half the rpm to get original voltage. You can take the the original circular mil size and devide by four and multiply the turns by four and multiply voltage by 4 but amps really start to drop. I have 2 cores here that I am going to bolt together and rewind with 22 gauge. It's 1/4 the circular mils of the 16 gauge that was in them. And I just happen to have a spool.
     
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