Sequence Components Obtained by Current Spectral Analysis in DC Motor Drives Working Under Abnormal Conditions.

Abstract

This paper presents some results about the line current spectral analysis in a DC motor drive under abnormal working conditions. The dependency of the relative frequency of a harmonic and its sequence (positive/negative) is illustrated. Under some of the abnormal conditions noncharacteristic harmonics result. The frequency or sequence of these harmonics are different that the frequency components obtained under normal conditions. It is shown the result of the spectral analysis in four cases: a) under unbalanced supply voltage b) under distorted supply voltage c) under mechanical unbalanced of the DC motor d) under shortcircuit in the armature of the DC motor