Opera-3d Magnetization and Hysteresis Module
The most important thing we build is trust
Alongside industrial partners, Opera has
The Opera (de-)magnetization and
hysteresis module enables users to model
both the magnetization process for hard
magnetic materials, and the hysteresis
behaviour of soft magnetic materials.
Users can simulate ferromagnetic
hysteresis with realistic demands on
resource, material data and with excellent
approximation to physical behaviour with
the Hysteresis material model.
With the ability to model the
magnetization process for hard
magnetic materials and remnant
magnetization vector, this Opera module
also allows users to simulate further
demagnetization and remagnetization of
the sample in situ.
developed a semi-empirical method for
modelling hysteresis. When users input a
measured major symmetric loop, easily
obtained from measurements or published
data-sheets, and imported into Opera as a
magnetic characteristic table, Opera can
supply a trajectory from the magnetic
behaviour.
turning points of the trajectory. It also erases
turning points when the magnetization of a
material exceeds the previous excursion. The
algorithm correctly transfers to the saturated
data, in the same way as for anhysteretic
materials in Opera-3d.
trajectory goes through an earlier turning
point. Usefully, Opera recognises oscillating
Hysteresis losses
fields and minimises the storage of turning
Using this capability, the module calculates
points.
the loss due to hysteresis in the hysteretic
Treating transition to saturation automatically,
All of Opera’s transient electromagnetic
phenomenon, Opera’s ability to model
including dynamics, rotating and linear
ferromagnet-ic hysteresis provides users
motion and demagnetisation.
transformers and electrical machines.
technique to determine minor loops and
out’ of minor loops, which occurs when the
Important, both as a useful and an unwanted
modelling can be used to minimize losses in
sophisticated algorithm uses a reconstruction
issues of nested minor loops and ‘wiping
simulations offer hysteretic material models,
engineering design. For exam-ple, hysteresis
data for the major hysteresis loop. Opera’s
material curve beyond the end of the user
the user’s data.
advantages in many areas of electrical
With this module users only need to supply
The Opera hysteresis model includes the
the simulation overcomes any limitations in
Hysteretic Materials
and motion electromagnetic solvers.
material during a transient calculation. At each
output time, Opera can display the energy
density (the sum of the stored and dissipated
energy since the beginning of the transient
simulation).
.
Opera-3d offers users the ability to model
hysteretic materials under transient
conditions using a B(H) trajectory-following
algorithm. Users can simulate hysteretic
materials in conjunction with the transient
Hysteretic material properties, left, can be
applied to an actuator model, right. This introduces a delay, as seen in a typical response,
above.
Opera-3d Magnetization and Hysteresis Module
OperaFEA.com
Opera-3d Magnetization and Hysteresis Module
The most important thing we build is trust
Magnetization and Demagnetization of
standard Opera transient solvers. In such a
Permanent Magnets
simulation where the applied field from current
sources etc are opposing the magnet’s field,
With hard magnetic materials, the
the variables will show the operating point of
simulation records the progress of the
the magnet. In a transient simulation, they
material magnetization along the virgin
will show the lowest operating point that was
characteristic, until the magnetizing field
reached during the transient event.
starts to reduce. Secondary ‘demagnetization’
characteristics are then used to determine
the remnant magnetization vector when the
magnetization process is complete. In both
the magnetization and demagnetization
processes, the effect of eddy currents and
circuit transients are captured.
Remagnetization:
Magnetization:
During the magnetization process, the
maximum value of the flux density in each
element is monitored and stored.
If the flux density in element moves into the
irreversible part of the 2nd (or 3rd) quadrant
curve, i.e. goes beyond the knee of the
curve, and the demagnetizing field is then
subsequently removed, the remagnetization
curve is a straight line defined by its slope (the
The result is a magnetized sample, where
recoil permeability) and the relevant point on
the magnetization distribution is correctly
the demagnetization curve.
defined. This can then be used in other
simulations to model the performance of
Demagnetization in service can be modelled.
the magnetized sample in its designated
The minimum field will be tracked and updated
application (eg. an electrical machine).
during subsequent simulations, and the
appropriate demagnetization curve or recoil
During the simulation of the application
permeability will be used.
further demagnetization and remagnetization
of the sample in the application device due to
the presence of current sources can also be
modelled.
Demagnetization:
During demagnetization, the values of
The Opera-3d (de-)magnetization analysis
the pre-stored values determine which
module (DEMAG) can be used to compute
demagnetization (second quadrant) curve
the magnetization of permanent magnet
each element follows and its direction of
materials by time varying electromagnetic
magnetization. Again the flux density in
fields in three dimensions including the
each element is monitored and the minimum
effects of eddy currents.
values are stored in variables.
It covers three scenarios:
The values can then be transferred to the
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