Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Designing a three phase permenent magnet generator

  1. Feb 18, 2006 #1
    I am designing a three phase permenent magnet generator , and have a question.
    as a magnet pair passes over a coil , inducing a voltage, that voltage is most dependent on ?
    1) the angular velocity ( thats a given)
    2) the pole strength
    3) flux density
    4) energy product.
    5) thickness of the magnet ( not the width / length or diameter)

    Assuming the diameter of the magnet is in the correct proportion to the coil for a three phase generator how is the the thickness of the magnet related to the induced voltage?
    I have experimented with this , using 7/8" dia x 1/2" and 7/8" dia x 1" NdFeB magnets , with the same air gap , same coil , doubling the thickness only produced a 15 percent increase in voltage . why?
    I was expecting to double the induced voltage .
  2. jcsd
  3. Feb 18, 2006 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Can you provide a simple diagram of the geometry. It may just be that you are adding the extra thickness at a greater distance from the coil, and hence, not providing twice the field at the coil.
  4. Feb 18, 2006 #3
    yes i have diagrams , but would like to ask first , are my thoughts on doubling the thickness , and hence getting double the voltage , essentially correct?
  5. Feb 19, 2006 #4
    have you checked your private messages , i sent you one on feb 7th.
    i dont know who else to turn to for an answer, the gap is adjustable and is essentially the same @ 0.460" , for both tests.
    my test coils are 0.390" thick. i have several.
    0.035" space top and bottom..
    this is a dual rotor machine 24 poles , 48 magnets
    magnets are 7/8" dia , coils are 1.75" dia,with a 7/8" hole
    rotors are 10.8" dia
  6. Feb 23, 2006 #5
    Thanks for the reply , i really appreciate it
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook