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Rare Earth Magnets >> Permanent magnet motor >> New Permanent Magnet Motors |
New Permanent Magnet Motors From ABB Eliminate Gearboxes
A unique new line of low-base-speed permanent magnet AC motor s from ABB is the heart of a system known as the DriveIT Direct Drive Solution. This consists of a DriveIT permanent magnet synchronous AC motor , controlled by a DriveIT low-voltage AC drive, based on the ACS 600 or ACS 800 AC drive and connected directly to a motor /load, without gearboxes or pulse encoders.
"This is another quantum leap in the elimination of mechanical equipment ? gearboxes ? that often makes motor /load control bulky and difficult," said Jan-Anders Bergman, vice president and general manager of Electrical Machines, for ABB Inc., Automation Technologies.
"With the complement of this motor to ABB Direct Torque Control? drive technology, end users now gain even more precise load control and are able to operate the motor without an encoder."
Permanent Magnet Motor is Synchronous and Eliminates Brushes, Rotor Windings -- ABB's permanent magnet motor is an AC synchronous motor . With such a motor , there is no rotor slip, which provides better accuracy than standard, asynchronous, motor s (see sidebar). In an asynchronous (or induction) motor , the slip varies according to speed and load. With a synchronous motor , it is simpler to optimize the speed, and the elimination of slip compensation improves the dynamic motor control, according to Bergman. In addition, the elimination of slip losses in the rotor of the motor increases the efficiency of the motor from one (1) to three (3) percent.
The permanent magnet s in the new ABB motor simplify traditional synchronous motor construction by creating a constant flux in the air gap that eliminates the need for the rotor windings and brushes normally used for excitation in synchronous motor s. "The result is a motor that combines the high-quality performance of the synchronous motor with the robust design of the asynchronous induction motor ," Bergman noted. "And the motor is energized directly on the stator by the variable speed drive."
More Power From A Small Frame Size; NdFeB Magnet s --
The new synchronous motor also can deliver more power from a smaller unit. To power the in-line drives of a paper machine directly at 220 - 600 rpm with a conventional asynchronous motor would require a motor frame substantially larger than that of a 1800-rpm motor . The new permanent magnet motor type has, in most cases, the same size or is even smaller than an existing induction motor .
Permanent magnet s utilized in the ABB motor s are made from neodymium iron boron (NdFeB) ? the newest magnet ic material on the market. NdFeB is the most powerful magnet ic material at room temperature available, with high values of flux density at very high values of magnet ization. It is also extremely
resistant to de magnet ization. And NdFeB is less costly and less brittle than samarium cobalt, another rare earth material used widely in the 1980s.
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