Fisher @ Paykel

Discussion in 'General Electronics Chat' started by lozza47, Nov 9, 2013.

  1. lozza47

    Thread Starter New Member

    Nov 9, 2013
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    Hi all,
    The BIG DUMMY here, can someone tell me what depicts the voltage output "as in AC or DC" in a Permanent Magnet motor, : EG: i have a 90 Volt DC PM motor, if i connect up my battery drill to the drive shaft of the motor and turn it, what will i get out ?? AC or DC ?? and the same question in regards to the fisher @ paykel AC washing machine motor, what is the output ?? AC or DC, my project is to make a wind generator, small and compact to trickle charge my deep cycle batteries on my camping trips.
    regards Laurie
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    Use a Brushed DC motor, not an AC motor, you need the magnets to make the field for the rotating coil.
     
  3. Ramussons

    Active Member

    May 3, 2013
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    1. You will get DC

    2. I presume its a normal Induction Motor. Normally you will get no output - you may get small AC if there's some residual magnetism on the Rotor.

    Ramesh
     
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  4. shortbus

    AAC Fanatic!

    Sep 30, 2009
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  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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  6. lozza47

    Thread Starter New Member

    Nov 9, 2013
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    OK guys, so if i use a Brushless Motor the output will be AC and if i use a Brushed Motor the output will be DC ?????????? IS THAT RIGHT ???????????
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Yes, as long as it has a P.M. field.
    Max.
     
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  8. lozza47

    Thread Starter New Member

    Nov 9, 2013
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    AH HUH !!!!!!!!!! Thanks Max, so with my 90 volt DC motor hooked up to a fan blade system i will get output of DC and next question is : how many DC volts output and Amps etc can i expect ???, etc, is there a formulae to work this out ?????? obviously RPM comes into somewhere ??
     
  9. MaxHeadRoom

    Expert

    Jul 18, 2013
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    For a DC brushed the maximum rpm on average maxes out at around 2500-3500 and the voltage in at that rpm is also equivalent to the generated voltage at the ref rpm.
    IOW, there is two way to derive voltage constant in V/kRPM (Ke), one is to back feed the motor at a known rpm and measure the DC and extrapolate for the estimated or known max rpm.
    The other is to feed a known voltage and measure the rpm and again it is directly relative.
    The continuous stall torque Lb-in (Nm) is based on the rated current, the torque for a DC motor being maximum at zero rpm and usually tapering off slowly up to maximum rpm.
    There are tests but you can often get very close by comparing frame size etc.
    Max.
     
  10. lozza47

    Thread Starter New Member

    Nov 9, 2013
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    Heavens above, this is getting over my head, i am the dummy and you are obviously the expert and i thank you for your time, you gotta talk to me in dummy terms LMHO, so the way i look at it is EXAMPLE: i run my 90v dc motor at 90 vdc and it runs at 2500 rpm, SO if i connect up a fan blade and the wind blows the 90vdc motor at 2500 rpm i should expect 90vdc out ??????? am i on the right wave length here ???????
     
  11. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    You obviously haven't read the link i gave in post# 2, as there is a formula to work out Volts per Ratio rpm..
     
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  12. MaxHeadRoom

    Expert

    Jul 18, 2013
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    On an efficient P.M. motor, there is very little difference between powered and generated voltage as it pertains to off load voltage relative to a given rpm.
    This is only used to obtain the initial V/kRPM (Ke) of the motor.
    Max.
     
    Last edited: Nov 9, 2013
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