Radial flux Alternator rotor magnet configuration

Discussion in 'General Electronics Chat' started by henry newton, Apr 13, 2010.

  1. henry newton

    Thread Starter Member

    May 5, 2008
    Here is my question.

    Consider a radial flux alternator that has two pole rotor at the center.now a typical orientation would be a N-S, But what i want to use is N-N orientation.The rotor would look like a N-S ring neo magnet that is magnetised along it's curve faces( i.e radially magnetised) with a outer north pole and inner south pole.This means that a north pole will always be facing the coil of wire.

    Here is the trick, the neo magnet will be fixed, while a laminated iron ring of fairly larger diameter would be place around the magnet. It is this laminated iron ring ( which would act as an induced rotor magnet ) that would be rotated around the fixed ring neo magnet located at it's center.

    The only merit of this configuration as i can imagine is that it allows you to use a bigger,stronger ring neo magnet and never bother about what it will take to rotate it as it will be fixed, rather it is the lighter laminated iron ring (which becomes a magnet by induction) that will be rotated.

    A lighter rotor should mean less fuel burn to spin the rotor.Also it will make it more practical and convienent to use a superconductor ring magnet as a "fixed-rotor" which also you don't have to rotate.

    Is it possible to build an efficient alternator as illustrated above
  2. retched

    AAC Fanatic!

    Dec 5, 2009
    The weight of the rotor isn't typically the problem because of the use of bearings.

    The strength of the magnetic field increases as current increases creating more drag on the rotor. That is the "problem"
    Also, I think it is pretty much a requirement that the N-S reversals fluctuate the field or you will not create any power at all.
  3. SgtWookie


    Jul 17, 2007
    Rotor mass comes into play when changing the rotational speed (or accelerating/de-accelerating the entire assembly, as in a moving vehicle) and perhaps a slight effect on gyroscopic precession when the assembly is turned at right angles to the direction of rotation, but otherwise it's fairly inconsequential.

    Improving the aerodynamics could help with air resistance, but then cooling might become a problem.
  4. JDT

    Well-Known Member

    Feb 12, 2009
    Not sure that this will work. How are the wires in your coil cutting the magnetic field? To put it another way, the magnetic field that the coils see needs to be CHANGING to induce current in the coils.

    It seems you have fixed magnet and fixed coils?

    Please explain more.
  5. retched

    AAC Fanatic!

    Dec 5, 2009
    Thats what I wat concerned with. If the magnetic field wasnt changing between north and south, It wouldnt matter if it were spinning. To the field, it would be the same as if it was standing still.
  6. davebee

    Well-Known Member

    Oct 22, 2008
    Magnetic flux lines are loops, so flux lines from the South poles will find some path from the center of the rotor up to the North poles.

    With the conventional magnetic configuration, the lines of flux are designed to pass directly across the gap that the coil moves through.

    With a N-N orientation I'd be concerned that much of the flux from the South poles would wind around and rejoin the North pole through the sides of the magnets rather than being constrained to cross the gap as in conventional design.

    If the flux path does not cross the gap where the coils pass through then that portion of the magnet is being wasted; it's not contributing to power generation.

    So while I imagine that while the coils would find some flux to pass through, this would not be using the magnets in their best efficiency.