Patent ID: 7750663
Filing Date: 2010-07-06
Classification: G01R,H02K

Abstract:
1. A method for off-line testing of an electric motor, which comprises stator windings and a rotor arranged along a rotation axis, comprising measuring a physical quantity of the stator winding while the rotor is being rotated about the rotation axis, wherein periodic measuring data concerning the physical quantity are obtained, characterized by; applying a periodical test signal to at least one of the stator windings; collecting first measuring data from one or more waveform periods of the test signal; detecting peak values of the collected first measuring data; forming second measuring data based on the detected peak values of the first measuring data; comparing the symmetry between at least the fundamentals of two or more half-cycles of the collected second measuring data; and generating a signal, which indicates the symmetrical relationship between at least the fundamentals of two or more half-cycles of the collected second measuring data.