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