1952 1735 1985 Department of Physics & Astronomy
Progress in Permanent Magnets
In the last 100 years, the strength of the magnets [(BH)max and Hc] increased by a factor of 100.
Our Challenge
Single Phase Isotropic Decoupled Mr/Ms = 0.5 (BH)max = 12 MGOe
Single Phase Isotropic Exchange -Coupled Mr/Ms > 0.5 (BH)max = 20 MGOe
Nanocomposites Isotropic Coupled Mr/Ms > 0.5 (BH)max > 20 MGOe
This 2.5 MW wind turbine from General Electric
employs a permanent magnet generator, enabling higher efficiency at low wind speeds.
GE product brochure
Energy Generation
• Permanent Magnets • Soft Magnets
• Supercapacitors
Energy Storage
Novel Materials with High Energy & Power Density
George Hadjipanayis John Xiao
Department of Physics & Astronomy
Applications of Permanent Magnets
In a typical modern car permanent magnets are used in more than 30 places!
Department of Physics & Astronomy
Department of Physics & Astronomy
Magnetic Levitation Train
Magnetic levitation systems based on permanent
magnets (like "Inductrack", the electrodynamic permanent magnet system) are the most energy efficient and fail safe. Such systems, however, are still under development.
are based on Fe- or Co-rich rareearth alloys: Sm-Co, Nd-Fe-B
Fe
and Co provide the high magnetization and high Curie temperature Rare earth metals, such as Sm, Nd, Pr, provide the high anisotropy and coercivity.
More Efficient Rotors for Electric Motors
Surface Permanent Magnet Interior Permanent Magnet
High-performance
Nd-Fe-B sintered magnets are playing an increasingly important role in automobile and electric appliances driven by the issues of energy saving and efficiency. Inserted permanent magnet rotor has better efficiency than a surface mounted rotor.
Energy-Efficient Automotive Applications
Electric Power Steering Motor Hybrid Electric Vehicle Motor
Y. Matsuura. J. Magn. Magn. Mater. 303 (2006).
Department of Physics & Astronomy
Energy Efficient Magnetocaloric Materials
• Refrigerants
10000
TM R= 258.4%
High Efficiency Electronic Devices
• Spintronics*
8000
R (Ohm)
6000
4000
2000 -200 -100 0 100 200
must be of a nanoscale.
Department of Physics & Astronomy
Historical Development of Nanostructured Nd-Fe-B Magnets
100 100 (BH)max (MGOe) (MGOe) (BH)max 80 80 60 60 40 40 20 20 0 0
Department of Physics & Astronomy, University of Delaware, U.S.A. hadji@ jqx@
Department of Physics & Astronomy
Magnets for Energy-Related Applications
Department of Physics & Astronomy
Wind Turbines
Permanent magnets can replace the excitation
winding of synchronous machines and eliminate the need for a mechanical gearbox, coupling the wind turbine to the generator (to adopt a varying wind speed and the constant grid frequency).
Department of Physics & Astronomy
Modern Permanent Magnets
A high performance permanent magnet must have: a high remanence to produce a large magnetic induction a high Hc (Hc ≥ Mr/2) to avoid easy demagnetization a high TC to resist thermal demagnetization. Modern high-performance magnets
M agnetic Field (Oe)
Department of Physics & Astronomy
Energy Stored by a Permanent Magnet: Energy Product BH
For a given airgap, Vm is inversely
proportional to BH
The predicted (BH)max of the hard-soft composites exceeds 100 MGOe (59 MGOe is
th
Because the exchange interaction has very short range, the composite material
The signal amplitude from the precessing hydrogen
nuclei is a measure of the total hydrogen content, or porosity, of the formation.
Department of Physics & Astronomy
Department of Physics & Astronomy
Wind Turbines
This futuristic design also incorporates the magnetic levitation of vertical blades. The first "MagLev" wind turbine is allegedly now been built in China.
University of Delaware ENERGY INSTITUTE SYMPOSIUM March 17, 2008 Newark, DE
Novel Materials for High Energy and Power Density
George C. Hadjipanayis and John Q. Xiao
The superconducting magnetic bearing (SMB) suppresses the vibrations of the flywheel
rotor, whereas the permanent magnet bearing controls the rotor position.
Y. Matsuura. J. Magn. Magn. Mater. 303 (2006).