Method And Controller For Determining An Undesired Condition In An Electrical Drive System

摘要

A method for determining an undesired condition in an electrical drive system including an electrical machine and an electrical drive, wherein the method includes a) obtaining a measured signal of an electrical or mechanical parameter, b) obtaining a frequency spectrum of the measured signal, that contains a measured frequency component, c) determining whether the measured frequency component is within a predetermined distance from a trend line, which trend line is associated with only one specific frequency component of the electrical or mechanical parameter present during a specific undesired condition, d) on the condition that the measured frequency component is within the predetermined distance from the trend line increasing a counter associated with the trend line, e) repeating steps a) to d), wherein in case the counter reaches a predetermined number determining that the electrical drive system is subjected to the undesired condition associated with the trend line.

主权项

1. A method for determining an undesired condition in an electrical drive system comprising an electrical machine and an electrical drive, wherein the method comprises:
a) Obtaining, with a sensor, a measured signal of an electrical or mechanical parameter concerning the electrical drive system, b) Obtaining, with a processing unit, a frequency spectrum of the measured signal by means of the Fast Fourier Transform, which frequency spectrum contains a measured frequency component, c) Determining, with the processing unit, whether a point in the plane having as its coordinates a frequency value of the measured frequency component and the fundamental frequency of the measured signal is within a predetermined distance from a trend line, which trend line is associated with only one specific harmonic of the electrical or mechanical parameter present during a specific undesired condition, and utilising the Mahalanobis distance to determine a distance between the point and the trend line to determine whether the point is within the predetermined distance from the trend line, d) on the condition that the point is within the predetermined distance from the trend line, increasing a counter associated with the trend line, e) repeating steps a) to d), wherein in case the counter reaches a predetermined number within a predetermined number of iterations of steps a) to d), f) determining, with the processing unit, based on that the counter reaches the predetermined number that the harmonic associated with the trend line is present in the measured signal and thereby that the electrical drive system is subjected to the undesired condition associated with the trend line.