Magnetodynamic Freq.

The magneto-dynamic solution in frequency domain describes the distribution of magnetic fields and eddy currents due to time harmonic excitation loads.

We use a quasi stationary approximation. The assumptions are applicable in cases of dimensions << wavelength. Examples are motors, transformers and frequencies from 0 Hz to a few 100 kHz.

Features

  • 2D, 3D or axisymmetric Solution
  • coupled with Thermal solution possible
  • Outputs Plot:
    • Magnetic Fluxdensity, Magnetic Fieldstrength, Current Density, Eddy Current Losses Density, Hysteresis-, Eddy-, Excess Loss Density - steinmetz, Magnetic Potential (a-Pot).
  • Outputs Table:
    • RotorBand Torque - stresstensor, Magnetic Potential on Conductors - Fluxlinkage, Voltage on Coils, Voltage on Circuits, Electrode Voltage, Electrode Current, Current on Circuits, Power on Circuits, Eddy Current Losses, Hysteresis-, Eddy-, Excess Losses, Ohm Resistance, Coil Inductivity, Phase Shift.

Examples

Transformer Analysis Circuit Breaker Lamination Losses AC Cable
     

Theory and Basics

Formulations

The basis equations:
(1)        rot h = j
(2)        rot e = -δt b
(3)        div b = 0

Constitutive relations:
(4)        b = µ h
(5)        j = σ e

a-Formulation

The following a-formulation is used for 2D-Magnetodynamics.

Magnetic vectorpotential a:             
(6)        b = rot a
(7)        e = -δt a

Magnetodynamic  weak  a-formulation:
(8)            ( µ-1 rot a, rot a’ )Ω
                + (-µ-1 bs, rot a’ ) Ω
                        
+ (- ja’ ) ΩC
                + (σ δt aa’ ) Ωc
                        
= 0, for all a’ element of Ω

a-v-Formulation

The following a-v-formulation is used for 3D-Magnetodynamics.

Magnetic vectorpotential a, electric scalar potential v:             
(9)         b = rot a
(10)       e = -δt – grad v

Magnetodynamic  weak  a-v-formulation:
(11)           (µ-1 rot a, rot a’ )Ω
                + (σ δt aa’ ) Ωc
                + (σ grad v, a’ ) Ωc 
                + (σ δt a, grad v’ ) Ωc
                + (σ grad v, v’ ) Ωc
                      
= 0

Basic Example: Team Problem 3: The Bath Plate

The problem 3 of the TEAM (Testing Electromagnetic Analysis Methods) is one of the examples for testing eddy current codes. A conductive plate with two holes is placed under a coil. The coil is driven by alternating current of 50 Hz and 1260 ampere turns. The goal is to analyze for the magnetic fluxdensity along a line that goes slightly over the plate.

Point and Cylinder Example

The Mesh is shown in the following picture.

Point and Cylinder Example

Results: Fluxdensity and  Induced Current

The magnetic fluxdensity as contourplot

Fluxdensity of TEAM20

The magnetics fluxdensity as vectorplot
Fluxdensity of TEAM20

The induced current density as contourpolot
Induced currentdensity as contourplot

The induced current density as vectorplot
Induced currentdensity as vectorplot