MAGNETIC BEARINGS

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MAGNETIC BEARINGS

• Operation and the benefits of DDS Patented
  magnetic bearing systems

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Magnetic Bearing Types
MAGNETIC BEARINGS
ACTIVE Explicit Feedback
PASSIVE Implicit Feedback
HOMOPOLAR
HETEROPOLAR
Current Biased
Permanent Magnet Biased
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Heteropolar Magnetic Bearings
The bias flux in the air gap changes direction
several times around the circumference of the
rotor at a particular axial location

• Additional losses being created due to
• Current constantly being applied to provide the
  bias
• Change in current flux direction on rotor,
  increased with speed

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Homopolar Magnetic Bearings
The bias flux in the air gap stays in the same
direction around the circumference of the rotor
at a particular axial location
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Operation of a Conventional System
Heteropolar current bias radial bearing
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Operation of a Conventional System
Homopolar current bias axial bearing
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Layout of Conventional System
Three bearing cartridges for 5 axis of control
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Operation of a Homopolar System Permanent Bias
Radial Bearing
Permanent magnets provide the bias flux Single
amplifier is needed for each axis of control
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Operation of a Homopolar System Permanent Bias
Radial Bearing with a Helper Pole
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Operation of a Homopolar System Permanent Bias
Combination Bearing
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Benefits of PM Hompolar Bearings

• Permanent Magnet Bias
• Provides the bias flux without
• Electrical current without its energy losses
• Adding wiring and electronics
• Much more efficient vs. conventional
• Does not need any active cooling
• Permanent Magnet Helper Pole
• Creates additional thrust load capability without
  the need of additional coils, current and
  controls
• Combination bearing
• Single cartridge for both radial and axial
  positioning
• Occupies less space on the shaft
• Allows for
• Higher speed operations
• More stiff and robust shaft

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Bearings in Cartridge Form
Easily assembled serviceable
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Magnetic Bearing Control Loop
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Magnetic Bearing Control Box Hardware

• Sensor Card
• CPU
• DSP with TI C62
• 14KHz sampling rate
• Amplifiers (5)
• DC Power Supplies
• Power consumption for complete magnetic bearing
  system for a 2MW integrated compressor
• 200W - 400W Nominal

Magnetic bearing controller L 15in (381mm, W 18in
(457mm), H 9in (229mm) Weight 42lbs (19kg)
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Layout of DDS System with DDS patented magnetic
bearings
Force