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Constant Reluctance Brushless
Motor Description
The constant reluctance brushless motor is designed
without the use of laminations employing teeth.
The lamination stack is constructed using smooth
cylindrical laminations. Thus rotor “sees”
the same magnetic reluctance, which is independent
of rotor angle, hence no cogging torque.
The winding configuration can then be integrated
with the magnetics of the rotor to give excellent
sinusoidal back EMF wave-forms. Typical values
of distortion for these motor designs are approximately
2.5% for the third harmonic and 0.3% for the fifth
harmonic. The windings are mechanically captured
by a non-conductive, non-magnetic structure and
then epoxy impregnated. The motors described in
this catalogue all have two-phase windings. Three
phase windings are also available. The motors
are described with either redundant or non-redundant
windings and for internal or external rotor mounting.
Both configurations are catalogued for each motor
size.
The rotors use high-energy product Neodymium-Boron-Iron
magnets to develop the flux density needed across
the typically large magnetic air gap. Samarium
cobalt magnets are also available for those applications
requiring exposure to temperatures in excess of
150C. The rotor back iron and the stator lamination
thickness are designed to just fall below the
saturation levels for the materials. The motors
are engineered to develop the maximum torque for
the lowest power and the lowest weight for a given
form factor. The motors use materials which meet
the outgassing requirements of < 1%TML and
< 0.1% CVCM required for critical space
applications.
Other low outgassing materials are available
for specific applications, which require lower
viscous drag torque, higher torque per unit weight
and or higher temperature operation.
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more information, contact: |
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Phone: |
(631) 231-9100 |
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Fax: |
(631) 231-8375 |
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Brushless
DC Motors
