Methods and apparatuses for detecting the speed of an asynchronous motor
AssigneeEl-Fi Innovationer AB
InventorsBo A. Elfner, Anders P. P. Comstedt
Life of this patent
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Abstract
For determining the speed of an asynchronous motor use is made of the most manifest tone in the frequency spectrum beneath an overtone to the basic tone of the motor current. The frequency difference between the overtone and the tone in the subjacent frequency spectrum is determined, and thereby the slip and speed of the motor can also be established.
Claims9
A method for detecting the speed of an asynchronous motor, wherein components of the motor current in one frequency band beneath an overtone to the basic tone of the motor current are separated, wherein the frequency difference between the overtone and at least one of said components is determined, and wherein the slip, and thereby the speed of the motor, is determined from the frequency difference.
Dependencies are inferred from the claim text.