Importance of magnet width

[windrules]

Hi guys I have had up a 3/4hp single phase/2phase 240 volt genny up and running for about 6 months.Best power I have had from it is a little over 20 amps.It spins up well ,but I think my lack of output is due to,too narrow magnets.I have 4 only rows of 7/8th inch round neo,s on a square base.I think this may be too narrow and reducing output,possibly by about half.Not realy complaining because it far outperforms my old tapedrive motor,just interested what others think.

Kind regards,

Mos

[wildbill hickup]

Zubbly has an extencive posting on rotor design.

http://www.fieldlines.com/story/2004/8/13/214144/026

Hope that gets you there, if not Do a search for PART #2 Induction conversion. From what I gather the magnet should be as wide as the inside diamiter of the coil.

Wildbill

[windrules]

Thanks Wild Bill,

That is partly what I was looking for. The other part is how much does this being right effect performance?

regards,

Mos

[Flux]

With the ideal magnet width you will have 2/3 to 3/4 of the circumfrence covered with magnets.

If the magnets are too narrow you will be short of flux. If too wide you will have excessive leakage between magnets but the total flux is still likely to be higher so really the more magnet material you can squeeze in the better as space is always seriously limited with motor conversions.

Wide magnets do not follow the curve properly and there are large air gaps so it is generally better to make each pole of multiple smaller magnets but you will have radial gaps between the magnets.

Until someone comes up with curved magnets it is always a compromise.

When you have enough magnet material to saturate the teeth you will have virtually maximum output any more will produce mostly iron loss and excessive cogging.

Flux