What can I do with this motor I found?

Discussion in 'General Electronics Chat' started by tom66, Oct 27, 2011.

  1. tom66

    Thread Starter Senior Member

    May 9, 2009
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    An office adjacent to my dad's place has been over the years piled up with junk. I was told by the landlord you can take whatever you want from there because it's all going to be cleared out soon.

    I got a coffee machine (don't drink coffee but my dad does), two reasonably high spec computers (*full* of confidential information - don't worry I'll be doing a disk erase later), a packet of 6 year old crisps but most interestingly a universal motor which looks like it was from a washing machine.

    The motor says "220 - 240VAC, 440W, 50 Hz". So it's got about 3/5th of a horsepower, but I could probably get a bit more from it if I need to. (Still not enough for an electric car...) It definitely looks worn - the coils are darkened - but it seems okay from a cursory inspection.

    Is there anything particularly useful I could do with this motor?
     
  2. chrisw1990

    Active Member

    Oct 22, 2011
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    depending on space, perhaps a wind turbine? though depend on how easy it was to turn..
    but could gear it :)
     
  3. Sparky49

    Active Member

    Jul 16, 2011
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    Use it to make an electric bike?

    A believe someone on this forum has a blog which shows them modifying their push bike to run with a starter motor!

    Alternatively, you could try to make a novelty bow-tie, but the motor might be a bit bulky for that!:p
     
  4. chrisw1990

    Active Member

    Oct 22, 2011
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    a mains motor on a bike? a starter motor i could kind of understand, small, high torque, 12volts (ish)

    mains..? that would be the ultimate theft protection for a bike though.. electrify the frame;)
     
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  5. strantor

    AAC Fanatic!

    Oct 3, 2010
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    universal motor can be run on DC, doesn't need mains. But remember it's going to take 220V of battery if you want to even get close to the performance of a washing machine. AFAIK can't be used to generate power, as there are no magnets in it and it's not seperately excited, so you can't put independent current through the field. maybe suitable as a large power tool replacement motor if one goes out, keep it hand I'd say.
     
  6. Sparky49

    Active Member

    Jul 16, 2011
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    Yeah, attach a small substation on a trailer to the bike. Simples.:D
     
  7. chrisw1990

    Active Member

    Oct 22, 2011
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    sorry, dont understand, explain pls :)
     
  8. tom66

    Thread Starter Senior Member

    May 9, 2009
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    Wait, I'm an idiot... Does a universal motor have brushes?

    It also has a speed rating: 11200rpm.

    It's at my dad's office, so I don't have a pic yet.

    It would be interesting to try and generate electricity from it. Would probably go with the approach of rectifying it into HVDC (~340V) and inverting it back to AC; that way a constant frequency and voltage can be maintained.
     
  9. strantor

    AAC Fanatic!

    Oct 3, 2010
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    In order to generate current, a conductor needs to break magnetic lines of flux. Meaning, magentism needs to be present. In generators, large permanent magnets create the magnet field necessary for power generation. In car alternators, there are no permanent magnets, rather current from the battery is passed through a field winding, generating a magnetic field through which conductors move, to generate power, to charge the battery back. in a series wound motor, current comes in (from a source), goes through the field coil, generating a magnetci field, then through the armature, then back to the source. in order to make a series wound motor generate current, you would need to seperate the field and the armature (seperate excitation) and pass a current through the field like an alternator does.
     
  10. strantor

    AAC Fanatic!

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    yes it has brushes (if its a universal mtr)
     
  11. tom66

    Thread Starter Senior Member

    May 9, 2009
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    Okay, so generating power is not possible... Darn it. Would it be possible to modify it to generate power?
     
  12. chrisw1990

    Active Member

    Oct 22, 2011
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    ahh my bad, i assumed alternators ran with permanent magnets in them too! oh wow, time for bed, iv learnt my one new thing today!:p
     
  13. chrisw1990

    Active Member

    Oct 22, 2011
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    you can generate power with it..
    it just doesnt work like an alternator, (branched off from the conversation about bikes)
     
  14. strantor

    AAC Fanatic!

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    I wont say "yes" but ill say "probably" - if you isolate the field winding and pass a current through it. How much, I have no idea but my hunch says it wouldnt be very efficient or powerful. Btw it would be dc, no need to rectify it.
     
  15. chrisw1990

    Active Member

    Oct 22, 2011
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    arent we talking about his AC motor?
     
  16. strantor

    AAC Fanatic!

    Oct 3, 2010
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    A universal motor is nothing but a series wound DC motor with low reluctance laminated stator, so it is optomized to run on AC (but still more optimal for DC use). . If you swap the polarity of a series wound DC motor, the rotation stays the same. So, it doesn't matter that the AC keeps reversing polarity, the motor doesn't care. If you want to change the direction of rotation, you have to swap the field wires.

    these motors run on AC or DC
     
    Last edited: Oct 27, 2011
  17. chrisw1990

    Active Member

    Oct 22, 2011
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    my bad.. motors arent my strength =]
     
  18. strantor

    AAC Fanatic!

    Oct 3, 2010
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    thats fine, I just learned about universal motors a couple of weeks ago
    http://forum.allaboutcircuits.com/showthread.php?t=60478
     
  19. chrisw1990

    Active Member

    Oct 22, 2011
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    nice! i guess at the end of the day, its better to admit you dont know than pretend you do!
     
  20. tom66

    Thread Starter Senior Member

    May 9, 2009
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    Okay, so the wind power idea appealed to me.

    I'd like to see if I can run a 32" LCD off it. Power consumption 180W max. 180VAC - 270VAC (according to the service manual.) Perhaps other items, too.

    Would the motor keep a regular frequency and voltage? I doubt it. So I would need to build a small inverter for it. I have little experience in this field, but I used LTspice to produce a simple boost converter which generates ~340VDC from a 150VAC - 240VAC source.

    Next step is to make a full h-bridge inverter, modified sine wave (probably), with true sine wave being an upgrade.

    This design gets an efficiency of 99% according to LTspice... I wish!! MOSFET losses will be the highest loss, next to inductor resistance losses. I predict the real world efficiency to be close to 80-85%. A fan will be necessary to keep the unit cool.

    Goal size for the PCB (*including the inverter*) to keep costs down: 10 cm x 15 cm. 2-layer 8/8.

    +12V supply will be provided by a wall wart. In future it would be good to boost strap the converter from the wind turbine, but for now it will just be easiest to run the control logic from a wall wart.

    Isolation from the turbine is not important. Unit will be sealed.
     
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