Induction motor eccentricity study

1.  Introduction
 Literature Review
 Problem Statement
 Aims and Objectives
 Proposed Methodology
 Simulation Model
 Future work
 References
1
Outline

2.  Induction machines are used in daily life as well as in the industry with different
applications.
 The widespread use of squirrel-cage induction motors in the industry is due to their
low cost and reliability of use.
 Rotor eccentricity is a common problem for induction motors.
 The uneven air gap between stator and rotor of IM is air gap eccentricity. There are
two types of air-gap eccentricities, static and dynamic.
 It can result from motor manufacturing and assembly processes or from a range of
mechanical problems such as an unbalanced load or misalignment.
2
Introduction

3.  With static eccentricity, the minimum air-gap position is fixed in space, while for the
dynamic, the center of the rotor and the rotational center do not coincide so that the
minimum air gap rotates.
 Air-gap eccentricity must be kept to an acceptable level, for example, 10%.
 Unacceptable levels of eccentricity will occur after the motor has been running for a
number of years. The air-gap eccentricity can be detected by using the stator core
vibration and the stator current monitoring.
 For that reason, early fault detection is considered necessary for the safe maintenance
of the motor.
(continued)

4. Literature review
Reference Technique Remarks
A Yu Prudnikov
(2020)
• The author uses dependences of
the angular velocity of rotation of
the rotor, stator current, and torque
on the shaft versus time for various
technical conditions of the
induction motor.
• Increase in rotor eccentricity Change in stator current leads to
an increase in stator current and electromagnetic moment,
which in aggregate negatively affects the operation of an
induction motor and reduces its service life.
G. C. Stone and J.
Kapler (1998)
• Stator current signal analysis is
now a popular tool to find out
stator-winding faults with the
advantage of cheap cost, trouble-
• Fault conditions in induction motors cause the nonuniform
magnetic field in the air gap of the machine resulting in
harmonics in the stator current. It can detect broken rotor
bars, rotor eccentricity as well as mechanical faults on

5. Reference Technique Remarks
Sreedharala
Viswanath
(2020)
• Using the finite element method, a
three-phase induction motor is
modeled for healthy and eccentricity
fault conditions, with parameters such
as torque, speed, radial air-gap flux
density. and induced torque, voltage,
flux density, and flux distribution.
• When eccentricity is increased, the FFT spectrum indicates
the addition of noise. The index rises. The voltage distortion
in the eccentricity fault machine is shown by the induced
voltage plot. On increasing the eccentricity fault index, pulse
distortions may be seen in the torque and speed.
G. Mirzaeva
(2018)
• The size of the first-time harmonic was
calculated and analyzed with respect to
the stator angle to determine static
eccentricity from the stator-referred air
gap flux density. This magnitude was
acquired experimentally over a number
• The following estimation was made using this data δst
m/δ0
=3.90 (Magnitude of air-gap) percent and (angle) αst=1070
relative to the 00 mark on the stator. A black line depicts the
estimated static eccentricity in relation to the stator. This
was ascribed to a parallel movement of the rotor axis owing
to gravity and loose bearings, and it corresponded to the

6. Reference Technique Remarks
Jan Sobra (2016) • Radial vibrations are evaluated based
on the experimental data in no load
and nominal steady state operations.
• The amplitude rise in the vibration harmonics is evident
in both no load and loaded operational states for rotor
eccentricity.
R. Rouaibia (2016) • Discrete Wavelet Transform (DWT)
with different approaches for the
diagnosis of induction machines to
detect faults and identify their severity.
• From the obtained results we came to know that using
DWT and the energies of the high-level DWT
decomposition, the mixed eccentricity faults could be
easily detected, even in the case of non-stationary
operating conditions (variable speed and load torque) of
the motor.

7. As many process industries rely on induction motor operations due to their reliability. In practice, induction machines
serve less due to various factors. One of the key parameters is the increment in rotor eccentricity. Induction machines’
condition-based diagnosis is a must to avoid machine failures.
(Problem Statement)

8. Comparing behavior analysis of
IM in normal with rotor
eccentricity.
Collecting machine eccentricity
data (faulty condition
waveforms) in abnormal
conditions.
Analysis of waveforms with
rotor eccentricity increment.
Aims & Objectives

9. 1. Simulation of IM model in
normal and rotor eccentricity fault
conditions.
2. Comparison of voltage, current,
and torque waveforms during
faulty and normal conditions.
3. Injecting harmonics (faulty
condition) and analyzing the
degree of rotor eccentricity.
Proposed Methodology

10. Proposed Model For IM

11. Transformation

12. Equations for Te and Wr

13. Sub Model for Te and Wr

14. SIMULATION MODEL

15. Dependency of Eccentricity on Speed

16.  We will be collecting data and graphs for rotor eccentricity using the Simulink
model of the induction motor.
 Analyze the motor behavior under rotor eccentricity fault conditions.
 Write the Thesis work based upon collected data and simulation results.
Future work

17. Task No. Task Name Nov-21 Dec-21 Jan-22 Feb-22 Mar-22 Apr-22 May-22 Jun-22 Jul-22 Aug-22 Sep-22
1. Literature Review

2. Project Proposal

3. Analysis of
Proposed Scheme

4. Simulation of the
scheme
 
5. Analysis &
Simulation
- -
6. Analysis of the
simulation results
- -
7. Writing up the
thesis
-
8. Final Write up &
thesis Submission
-
TIMELINE

18. 1. Debasmita Basak, Arvind Tiwari, S. P. Das (2006). Fault diagnosis and condition monitoring of electrical machines - A
Review.
2. W. T. Thomson, D. Rankin, and D. G. Dorrell (1999). On-line current monitoring to diagnose airgap eccentricity in large
three-phase induction motors—Industrial case histories verify the predictions.
3. T. W. S. Chow and G. Fei (1995). Three phase induction machines asymmetrical faults identification using bispectrum.
Dec. 1995.
4. A Yu Prudnikov, V V Bonnet and A Yu Loginov (2020). Virtual model of an induction motor with rotor eccentricity.
5. G. C. Stone and J. Kapler (1998). Stator winding monitoring.
REFERENCES

19. 6. H. Calis and P. J. Unsworth (1999). Fault diagnosis in induction motors by motor current signal analysis.
7. Sreedharala Viswanath (2020). Static Eccentricity Fault in Induction Motor Drive Using Finite Element Method.
8. G. Mirzaeva and K. I. Saad (2018). Advanced Diagnosis of Rotor Faults and Eccentricity in Induction Motors Based on
Internal Flux Measurement.
9. Jan Sobra (2016). Mechanical vibration analysis of induction machine under dynamic rotor eccentricity.
10. R. Rouaibia (2016). Detection of Eccentricity Fault in Closed-Loop Induction Motor Drive using Wavelet Transform
Reference