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Permanent magnet motors are 43% smaller
Published:  09 May, 2007

At the recent Hannover Fair, the Brazilian motor and controls manufacturer WEG unveiled a clutch of new products. These included:
º  a permanent magnet motor drive system;
º  a range of water-cooled motors;
º  high-efficiency motors designed for an extra-long service life;
º  washable motors for food and pharmaceutical applications;
º  motors for use in Zone 21 hazardous areas; and
º  a range of motors specifically designed to work in severe environments, for applications such as roller tables and laminators.

WEG PM motor

The Wmagnet PM (permanent magnet) motors (shown above) use powerful rare-earth magnets in their rotors, instead of conventional squirrel-cages. The magnetic rotors produce superior magnetic flows and higher torque capacities for the same output, resulting in motors that are about 43% smaller and 35% lighter than conventional designs. WEG says that in some applications, its PM motors will be able to produce the same output as conventional induction motors two frame sizes larger.

Because Joule losses resulting from currents circulating in the rotor are effectively eliminated, the PM motors have much higher efficiencies than even Eff1 induction machines. They are said to deliver their nominal torque constantly across a speed range of 150–3,000 rpm.

WEG has developed a new balancing technology which is said to result in extremely low vibration and noise levels. The small, efficient design of the PM motors also means that cooling fans can be smaller, cutting noise levels further.

The IP55-protected motors are being produced in ratings from 11–150kW. They cannot be connected directly to the power supply, but WEG has developed a special vector drive with PM-specific software. The motors can be operated at zero speed without needing encoders.

The permanent magnet motors are expected to go on sale in Europe within a few months.

At Hannover, WEG was also showing its CFW-11 inverter first seen at last November’s SPS/IPC/Drives show in Nuremberg.

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