Detection of Rotor Eccentricity in Wound Rotor Induction Machines Using Pole-Specific Search Coils

Abstract

This paper addresses the need to detect the rotor radial position in an electrical machine. When it is not centered it is referred to as rotor eccentricity. Cage induction machines can use the detection of sideband currents and this is studied extensively elsewhere. Wound rotor induction machines do not generate the same sidebands so an alternative detection method is needed. These machines are now popular generators in wind turbines. A simple method using pole-specific search coils is introduced and theory is developed to illustrate that rotor eccentricity leads to the generation of airgap flux waves with pole-pairs that are pm±1. This is tested using search coils in a 4 pole wound rotor machine. The method is found to successfully indicate the presence of rotor eccentricity.

Evaluation of Dynamic and Static Eccentric Faults in Turbo Generator

“…In order to determine the direction of rotor dynamic eccentricity, it is necessary to combine the voltage waveform calculated according to formula (15) and take the induction voltage of a single U-type coil as a reference. Next, take u 24 and the induced voltage u 2 of the No.…”

“…The method used to diagnose eccentric faults in permanent magnet motors using the specific frequency harmonic in the stator current was put forward in [8][9][10][11]. For induction motors, it has been proposed that the rotor eccentricity fault can be diagnosed by the stator current and different types of detection coils [12][13][14][15][16][17][18]. Compared with induction motors and permanent magnet motors with small volumes and capacities, the vibration caused by rotor eccentricity inside large synchronous generators is a Correspondence to: Yucai Wu.…”

The Detection and Suppression of Unbalanced Magnetic Pull in Wound Rotor Induction Motors Using Pole-Specific Search Coils and Auxiliary Windings

“…The work develops the idea of using pole-specific windings in order to detect rotor eccentricity. Initial results were put forward in [29]. Here, an impedance matrix is developed to predict the winding voltages as a function of eccentricity.…”

Diagnosis of Mechanical Unbalance Fault in Permanent Magnet Synchronous Machine Drives

“…Several diagnosis methods for mechanical unbalance faults have been put forward in the literature [3][4][5][6][7][8][9]. In [3], the effects of different types of eccentricity faults in a reluctance synchronous motor were analyzed to identify the faultspecific frequency components in the line current spectrum.…”

“…00 faults in the salient pole synchronous generator. In [7], the pole-specific search windings, which are placed at various top positions of the stator slots, were used to detect the rotor eccentricity in a wound rotor induction motor. In [8,9], a review of fault diagnosis of electrical machine was presented.…”