Permanent Magnet Motors Introduction and Trends

umurali2000

January 23rd, 13:03

Induction motor is preferred choice of manufacturer and customer primarily due its robustness, easy manufacturing, and low maintenance. But is this the most efficient motor? Answer is obviously no. Efficiency is function of losses, so let us revisit the Induction Motor losses as shown in figure1. Now if compare these losses with permanent magnet (PM) motor, we would notice that there is rotor copper loss which is almost 15 to 20% of overall losses.
As these losses goes down the cooling requirement of motor can be reduced.

PM motor offers following benefits over Induction Motor,
· No rotor copper losses
· Cooling of the motor only for the stator copper and iron loses, cooling requirements goes down
· Different size/ volume and arrangements of magnets on the rotor will lead variety of desired characteristics.
· Higher efficiency because of fewer losses.
· Compact high density magnets can reduce the overall size of motor

The indicative comparison of various parameters is covered in Conclusion.

If we compare various motor technologies as against design, performance and manufacturing parameters, following table helps to select the appropriate technology. The scale between Excellent and Positive is larger to magnify the difference in various technologies.

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