F R A U N H O F E R I N S T I T U T e F o R P h y si c a l M easurement T e c hni q ues I P M
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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
nous motors in electric cars. And they are
magnetic system. Fraunhofer IPM designs
Heidenhofstrasse 8
used in laboratory measuring equipment in
magnetic systems that are attuned to
D-79110 Freiburg, Germany
order to identify the properties of materials
customer-specific applications.
in a magnetic field. A possible field of
Contact
application is NMR spectroscopy, which
Scientists at the Institute are specialized
requires strong magnetic fields especially
in designing and constructing permanent
Dr. Kilian Bartholomé
for the analysis of large molecules.
magnet systems for refrigerant -free coo-
Group Manager
Expensive and sensitive superconducting
ling using magnetocaloric materials. These
Magnetocalorics and Electrocalorics
magnets are normally used in this context.
systems could offer an alternative to classic
Phone +49 761 8857-238
Permanent magnets made of modern
compressor-based cooling in the future.
kilian.bartholome@ipm.fraunhofer.de
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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Calculation of complex magnetic fields
is, the variation between zero and a finite
3 Geometry of an FEM model
magnetic field. Fraunhofer IPM constructs
yoke system.
During the construction of such systems,
arrangements of individual magnets in dou-
4 Implemented magnet system
simulations of the finite element method
ble or triple Halbach arrays with complex
with an integrated Halbach array
(FEM) are conducted in order to predict the
supporting systems and especially stable
for a tunable field strength.
magnitude, orientation, and location of the
non-magnetic materials. For instance, a
magnetic field. Losses due to stray fields
Halbach system that allows variation of
can also be calculated and thus minimized
field strength between 0.1 and 0.5 T was
by guiding the field through soft magnetic
designed and built at the Institute. To
materials. The optimum magnetic system
allow a field to be tuned, a certain number
design is developed on the basis of the
of individual magnets must be able to
simulation results. This involves not only the
change their positions. In the Fraunhofer
individual magnets, but, as required, the
IPM Halbach system, the control of the
use of an iron yoke or pole shoes. Various
movable individual magnets has already
material classes and special requirements
been integrated.
on the installation space can be observed.
Our offer
ƒƒ Design of permanent magnet
systems using finite element
simulation (such as Halbach arrays)
Halbach arrays for
tunable magnetic fields
ƒƒ Construction od magnet systems
including guiding of the field
through soft magnetic materials
Generating a magnetic field of a particular
and control of switchable magnet
magnitude is not the only purpose of
components
permanent magnets. The arrangement
of permanent magnets in Halbach arrays
© Fraunhofer IPM 12/2015; Bilder: Fraunhofer IPM
allows the tuning of a magnetic field, that
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