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RE: [FEMM] Unexpected inductances values!
Hi
I think, that you shold remove magnets (to set Hc to 0) if you use integral
A.J.
JV
> -----Original Message-----
> From: femm-bounces@xxxxxxxxxxxxxxxxxxxxxx
> [mailto:femm-bounces@xxxxxxxxxxxxxxxxxxxxxx]On Behalf Of Ahmad Eid
> Sent: Monday, May 10, 2004 8:57 AM
> To: femm@xxxxxxxxxxxxxxxxxxxxxx
> Subject: [FEMM] Unexpected inductances values!
>
>
> Dear all
>
> I'm trying to find the inductances (self and mutual)
> of four coils PM linear motor.
> I tried to folow the method that Dr David writes in
> the manual, but I confused. If there are PM in the
> design, I calculate the inductance with existing PM or
> I should remove them first to calculate the
> inductances.
>
> My calculations as follows:
> I applied 10 A in the fist coil only and each coil has
> 60 turns and using block integral and I don't remove
> the permanent magnets from the model:
>
> 1) the self inductance of coil 1 = integral (A.J) dv =
> -0.883457 Henry Amp^2 then dividing by current square:
>
> Lself = 8.8345 mH
>
> 2) the mutual inductance between coil 1 and 2
> L12 = integral (A)dv
> Integral of A over selection:
> 7.8108e-007 Henry Amp meter^2
> Integral of A / selected area:
> 0.00150133 Henry Amp
>
> L12 = 0.00150133 *Nturns/current=0.00150133*60/10 = 9
> mH
>
> 3) L13 = L12 = integral (A)dv
> Integral of A over selection:
> -7.55774e-007 Henry Amp meter^2
> Integral of A / selected area:
> -0.00145268 Henry Amp
>
> L13 = -0.00145268*60/10 = 8.716 mH
>
> 4) L14 = L12 = integral (A)dv
>
> Integral of A over selection:
> 9.24499e-007 Henry Amp meter^2
> Integral of A / selected area:
> 0.00177699 Henry Amp
>
> L14 = 0.00177699 *60/10 = 10.66194 mH
>
> As shwon from the four results that the mutual
> inductance is bigger than the self inductance and I
> think this is wrong.
>
> I don't know where are the mistakes
>
> any suggestion will be appreciated
> thanks all
>
> ahmad
>
>
>
>
>
>
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