FRAUNHOFER INSTITUTE FOR PHYSICAL MEASUREMENT TECHNIQUES IPM
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1 Magnet systems for movable samples.
2 Simulated magnetic field distribution
for a three-fold Halbach array.
PERMANENT MAGNET SYSTEMS
DESIGN, SIMULATION, AND CONSTRUCTION
Magnetic fields can be generated by
Customized design
electromagnet or permanent magnet
of magnetic systems
systems. The latter have several advantages
over electromagnets: They work without
Magnetic fields of a defined strength and
electricity and do not require costly cooling.
orientation can be generated by individual
Permanent magnets based on new mate-
arrangements of permanent magnets. One
rials have been on the market for several
of the significant challenges in the design
years and are being incorporated into appli-
and construction of magnetic systems is
cations in increasing numbers. For instance,
generating the strongest possible field with
Fraunhofer Institute for Physical
permanent magnets have already become
the least possible material, since material
Measurement Techniques IPM
established in permanent-magnet synchro-
is generally the biggest cost factor for a
Heidenhofstrasse 8
nous motors in electric cars. And they are
magnetic system. Fraunhofer IPM designs
D-79110 Freiburg, Germany
used in laboratory measuring equipment in
magnetic systems that are attuned to
order to identify the properties of materials
customer-specific applications.
Contact
in a magnetic field. A possible field of
Dr Kilian Bartholomé
application is NMR spectroscopy, which
Scientists at the Institute are specialized
Deputy Head of Department
requires strong magnetic fields especially
in designing and constructing permanent
Group Manager
for the analysis of large molecules.
magnet systems for refrigerant -free coo-
Calorics and Thermoelectrics
Expensive and sensitive superconducting
ling using magnetocaloric materials. These
Phone +49 761 8857-238
magnets are normally used in this context.
systems could offer an alternative to classic
[email protected]
Permanent magnets made of modern
compressor-based cooling in the future.
materials have the potential to be used for
During magnetocaloric cooling, permanent
generating magnetic fields of up to 2 T,
magnets stimulate the magnetocaloric
allowing light, portable analysis devices.
material.
www.ipm.fraunhofer.de/en
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3 Geometry of an FEM model
Calculation of complex magnetic fields
can also be calculated and thus minimized
yoke system.
by guiding the field through soft magnetic
4 Implemented magnet system
During the construction of such systems,
materials. The optimum magnetic system
with an integrated Halbach array
simulations of the finite element method
design is developed on the basis of the
for a tunable field strength.
(FEM) are conducted in order to predict the
simulation results. This involves not only the
magnitude, orientation, and location of the
individual magnets, but, as required, the
magnetic field. Losses due to stray fields
use of an iron yoke or pole shoes. Various
material classes and special requirements
on the installation space can be observed.
Our offer
Halbach arrays for tunable
magnetic fields
ƒƒ Design of permanent magnet
systems using finite element
Generating a magnetic field of a particular
simulation (such as Halbach arrays)
magnitude is not the only purpose of
permanent magnets. The arrangement
© Fraunhofer IPM 02/2017; pictures: Kai-Uwe Wudtke (1+4); Fraunhofer IPM (2+3)
ƒƒ Construction od magnet systems
of permanent magnets in Halbach arrays
including guiding of the field
allows the tuning of a magnetic field,
variation of field strength between 0.1
through soft magnetic materials
that is, the variation between zero and
and 0.5 T was designed and built at the
and control of switchable magnet
a finite magnetic field. Fraunhofer IPM
Institute. To allow a field to be tuned, a
components
constructs arrangements of individual
certain number of individual magnets must
magnets in double or triple Halbach arrays
be able to change their positions. In the
with complex supporting systems and
Fraunhofer IPM Halbach system, the control
especially stable non-magnetic materials.
of the movable individual magnets has
For instance, a Halbach system that allows
already been integrated.
ƒƒ Arrangement and construction of
magnet systems
Applications for systems consisting of permanent magnets
ƒƒ Magnetic cooling on the basis of magnetocaloric materials: refrigerant-free cooling
ƒƒ Laboratory systems for characterizing materials in a magnetic field
ƒƒ Systems for generating a magnetization in functional materials during manufacture, such as for hot press or
metal injection molding
ƒƒ Halbach arrays for tunable magnetic fields