Stator Winding Of Induction Motor Research Articles

Inter-turn stator winding fault diagnosis in three-phase induction motors, by Park's vector approach

The subject of on-line detection and location of inter-turn short circuits in the stator windings of three-phase induction motors is discussed, and a noninvasive approach, based on the computer-aided monitoring of the stator current Park's vector, is introduced. Experimental results, obtained by using a special fault producing test rig, demonstrate the effectiveness of the proposed technique, for detecting inter-turn stator winding faults in operating three-phase induction machines. On-site tests conducted in a power generation plant, using the diagnostic instrumentation system developed, are also reported.

Self-tuning of tapped stator winding induction motor servo drives using the universal field-oriented controller

The universal field-oriented controller is used to control induction motor torque and airgap flux independently of each other. The decoupling equations of the universal field-oriented (UFO) controller are identical for both direct and indirect field orientation. In this paper, a UFO controller is described that can operate both in a direct or indirect field orientation mode, allowing transitions from one mode to another. The proposed field-oriented controller can be realized at minimal cost in AC servomotor drives requiring motion control or accurate speed control. >

Multiple reference frame analysis of an unsymmetrical induction machine

Due to the asymmetry of the stator windings of an unsymmetrical induction motor, the equations which describe this device cannot be expressed in a frame of reference where the state variables are constant in the steady state. This prevents linearization and thereby places a stumbling block in the development of a transfer function which could be used in linear control analysis, as in servo applications. The work presented in this paper provides a means to accomplish this goal. This is achieved by eliminating the position-dependent terms brought about due to asymmetry by recognising a unique property of a combination of reference frames and by employing an averaging procedure. The resulting equations are shown to predict the performance of the unsymmetrical induction motor with the accuracy of the detailed equations. The stage is now set to develop accurate reduced-order models and linear transfer functions for unsymmetrical induction motors.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A Proposal for Insulation Diagnosis of 3 KV Motor Stator Windings

This paper presents a proposal for insulation diagnosis of 3 kV induction motor stator windings of mica splittings and solvent-type thermosetting resin insulation. Nondestructive and destructive tests were conducted on 29 windings it operation for 15 years or more. The average breakdown voltage (BDV), Vave of the coils was estimated using 10 to 12 coils from each winding. The relationship between Vave and Vmin, the BDV of the winding and the BDV of the worst coil in the winding, was determined. The criterion for insulation renewal, generally Vmin,7 kV (the withstand test voltage), could also be expressed in terms of Vave, with Vave≤l5 kV. Several nondestructive measurements were also examined for their ability to forecast Vave or Vmin. Although the dissipation factor tip-up (Δtanδ) should be related to Vave, no useful correlation was found. Partial discharge starting voltage (Vi) and the first turning point voltage (Pil) on the I-V curve in an ac current test proved to have comparatively good correlation with Vmin. A criterion for insulation diagnosis of that insulation is proposed, i.e. when Vi or Pil has decreased to 3 kV, the rated voltage, the insulation of the winding should be replaced.

A.C. diesel–electric drive system using consequential pole changing

The paper describes the development of a commutatorless diesel-electric drive system which uses an alternator and induction motors as the drive elements. The system provides a set of discrete final motor drive speeds at a fixed alternator drive speed, and so may be regarded as an electrical `gearbox?, a feature of the scheme being that, during normal operation, gear selection is carried out by pole changing the alternator excitation winding. Pole changing of the alternator output winding and the induction-motor stator winding is also used, but is a consequence of changing the alternator excitation pole number, and switching at full power level between the alternator and motors is thereby entirely avoided. The paper includes a sample design for a traction system having a continuous rating of 3600hp. The prediction of the performance of the sample design is substantiated by experimental results taken on a simplified laboratory model of the system.