advances in bl servo motors
TRANSCRIPT
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Advances in BL Servo Motors
“Slotless” Technology
Dan D’Aquila
2
1973, Corporate Headquarters, SWX Swiss Exchange Listed
1973, Servo Drives
1979, Servo Motors
1982, Servo DrivesNOTE: Mesa is now part of Lourdes FR
1979, Numerical Controls for Metal Forming Machines
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What is a better motor?
What is a better motor?Slotless benefits
• Toque
• Speed
• Smooth Motion
Power Density
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Smaller Size
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Cogging+Ripple+Friction Torque
-200
-100
0
100
200
1 91 181 271360º mechanical
Nm
m
NG-2 BL-74
Smooth Motion
Standard vs. Slotless
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How is this possible?
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How is this possible?
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SLOTTED DESIGNStator is made up of Stamped metal laminations and windings are wrapped around the teeth
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How is this possible?
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How is this possible?
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How is this possible?
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Stator Teeth
SLOTLESS DESIGNStator winding is made by wire wound on a form and potted in a special resin. – NO metal teeth!
Iron
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Compare Rotor
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Slotted Rotor Diameter
HIGHER TORQUE
Slotless Rotor Diameter (25-45% larger)
The result of redesigning the stator allows the Rotor to be larger by 25-45% which contributes to higher torque in the
same motor frame size.
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Magnetic saturation occurs at lower current in the slotted design because the teeth are the smallest iron cross section in the
magnetic circuit and limit the amount of magnetic flux possible.
The teeth are the weak link!
EVEN HIGHER TORQUE
Cross section of the tooth
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Magnets on the rotor are attracted to the steel teeth in the stator of a standard BL motor. As the magnet passes by the tooth a change or
modulation in the magnetic flux is created which in turn causes an induced voltage in the surface of the magnet per Faraday’s Law (e=dø/dt). As the magnets are conductive a current flows in them. These currents called
Eddy Currents increase exponentially with speed. This causes heat in the magnets and their magnetic properties diminish as they get hotter.
↑ω » ↑dØ/dt » ↑em » ↑Im » ↑tm » ↓ Magnet strength
HIGHER SPEED / POWER
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What is a better motor?
Infranor-Mavilor
What is a better motor?Slotless benefits
• Toque
• Speed
• Smooth Motion
Power Density
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Product Breadth & OptionsFrame Sizes, Torque Range
Flange, Feedback, Termination, Protection
