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

# Inductance with permanent magnet

- To: femm@yahoogroups.com
- Subject: Inductance with permanent magnet
- From: vecerkaj@yahoo.com
- Date: Thu, 25 Oct 2001 14:17:29 -0000
- User-agent: eGroups-EW/0.82

    Hello
    First, I would like to thank for the contribution to the discussion
    about ConText and other editors.
    Now, I have met a problem, how to calculate self inductance, if
    magnetic circuit contains permanent magnets (NdFeB-linear
    characteristics) and iron (nonlinear).
    My thinking: Calculation of L directly from the "A.J" integral is
    probably wrong, same as calculation of L from magnetic energy
    (because permanent magnets put additional energy to the magnetic
    circuit).
    My approaches how to solve that:
    1. To calculate inductance from model with magnet properties set on 0
    (Hc). But the magnetic circuit will not be saturated by magnets and
    result will not be accurate.
    2.To calculate model without current and with current. To make
    subtraction of energies obtained from the models. To use the result
    for calculation of inductance. I have realized, that this way is
    wrong.
    3. To calculate model without current and with current. To make
    subtraction of A in every node in mesh (mesh should be the same) out
    of FEMM and to create new .ans file. After that to calculate L
    directly from the "A.J" integral. Till now I think, that this way is
    correct, because this one considers iron saturation. I guess, if
    the "test" current is small then the method is applicable even for
    nonlinear materials.
    I have also a physical model, but the result obtained from FEMM is
    higher than reality I measured on the model ( about 100%). I don't
    understand why, because FEMM doesn't consider leakage inductance in
    winding heads, so the total inductance should be higher then
    calculated value.
    Note all the calculations I did were for 0 Hz (magnetostatic).
    So, I would like to ask anybody, what he thinks about the problem.
    Thank you in advance.

    Jiri Vecerka

- Follow-Ups:
  - Re: [femm] Inductance with permanent magnet
    - From: David Meeker <dmeeker@foster-miller.com>

- Prev by Date: Ynt: [femm] LEAKAGE REACTANCE
- Next by Date: Re: [femm] problem with lua function copyrotate
- Previous by thread: Ynt: [femm] LEAKAGE REACTANCE
- Next by thread: Re: [femm] Inductance with permanent magnet
- Index(es):
  - Date
  - Thread