[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

# [FEMM] Unexpected inductances values!

- To: femm@list.foster-miller.net
- Subject: [FEMM] Unexpected inductances values!
- From: Ahmad Eid <ahmad_m_eid@yahoo.com>
- Date: Sun, 9 May 2004 23:57:22 -0700 (PDT)
- List-archive: <http://femm.foster-miller.net/pipermail/femm>
- List-help: <mailto:femm-request@list.foster-miller.net?subject=help>
- List-id: FEMM mailing list <femm.list.foster-miller.net>
- List-post: <mailto:femm@list.foster-miller.net>
- List-subscribe: <http://femm.foster-miller.net/mailman/listinfo/femm>, <mailto:femm-request@list.foster-miller.net?subject=subscribe>
- List-unsubscribe: <http://femm.foster-miller.net/mailman/listinfo/femm>, <mailto:femm-request@list.foster-miller.net?subject=unsubscribe>
- Reply-to: FEMM mailing list <femm@list.foster-miller.net>

    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

    __________________________________
    Do you Yahoo!?
    Win a $20,000 Career Makeover at Yahoo! HotJobs
    http://hotjobs.sweepstakes.yahoo.com/careermakeover

- Follow-Ups:
  - RE: [FEMM] Unexpected inductances values!
    - From: "Jiri Vecerka" <vecerkajiri@seznam.cz>

- Prev by Date: Re: [FEMM] error in fkern-FEMM 4
- Next by Date: RE: [FEMM] Unexpected inductances values!
- Previous by thread: Re: [FEMM] error in fkern-FEMM 4
- Next by thread: RE: [FEMM] Unexpected inductances values!
- Index(es):
  - Date
  - Thread