O. Touhami

Fault Diagnosis in Industrial Induction Machines Through Discrete Wavelet Transform

This paper deals with fault diagnosis of induction machines based on the discrete wavelet transform. By using the wavelet decomposition, the information on the health of a system can be extracted from a signal over a wide range of frequencies. This analysis is performed in both time and frequency domains. The Daubechies wavelet is selected for the analysis of the stator current. Wavelet components appear to be useful for detecting different electrical faults. In this paper, we will study the problem of broken rotor bars, end-ring segment, and loss of stator phase during operation.

Magnetic Field Analysis of Inset and Surface-Mounted Permanent-Magnet Synchronous Motors Using Schwarz–Christoffel Transformation

In this paper, we apply an original numerical Schwarz-Christoffel (SC) transformation to analyze magnetic field originating from permanent magnets and the armature winding currents in a slotted air gap of an inset permanent-magnet synchronous motor. We obtained the solution of the SC integral numerically using Matlab SC Toolbox. We used this field solution to calculate both cogging torque and electromagnetic torque by integrating the Maxwell stress tensor inside the air gap. The case without inter-polar piece, which is equivalent to a surface-mounted permanent-magnet motor, is also treated. The accuracy of the developed method is verified by comparing its results with those obtained from the developed numerical finite-element models.

Analytical Model of Slotted Air-Gap Surface Mounted Permanent-Magnet Synchronous Motor With Magnet Bars Magnetized in the Shifting Direction

An analytical model is presented, which uses two-dimensional field theory in polar coordinates to determine the flux density distribution, cogging torque, back EMF and electromagnetic torque in the slotted air gap of permanent-magnet motors with surface mounted magnet bars which are magnetized in shifting direction. The magnet arc to pole pitch ratio in the motor is not necessarily equal to unity like in the case of Halbach array magnetization. The effect of stator slots is introduced by modulating the magnetic field distribution in the slotless stator by the complex relative air-gap permeance. With this complex permeance, the radial and tangential components of flux density are calculated. In the analytical and numerical study a finite number of magnet bars, which is considered sufficient to get a sinusoidal magnetization, is used. The influence of the number of magnet bars on magnetization is also investigated. The accuracy of the developed model is verified by comparing its results with those obtained from experimental measurement and previously validated linear and nonlinear numerical finite element code.

Experimental Investigation and Optimization of Permanent Magnet Motor Based on Coupling Boundary Element Method with Permeances Network

In the flrst part of this work, we develop a model to compute linkage flelds in Outer Rotor Permanents Magnets synchronous machines (OR-PMSM), a structure which is often used in the automotive traction motors. To carry out such a design, we usually employ Finite Element analysis (FEA) software even if it is time consuming. Other designers prefer the Permeances Network Method (PNM) which is less accurate and needs o†ine FEM results to evaluate the unknown air-gap permeances. Comparatively, between FEM and BEM, the flrst method is more precise whereas the second is faster in computing times. We propose here a new technique using the hybridization of both methods in order to gain the advantages of the two techniques, i.e., a relatively accurate and fast methods, so the high ratio of fast running to computing errors has been achieved. The second part deals with the multi-objective design optimization of the studied motor. To do this, we choose the decrease of cogging torque and the increase of torque as objectives applied to multi-objective optimization (MO) process.

Magnetic Field Analysis of External Rotor Permanent-Magnet Synchronous Motors Using Conformal Mapping

This paper presents analytical and numerical conformal mapping (CM) to analyze magnetic fields originating from permanent magnets and armature winding currents in a slotted air-gap of a surface mounted radial permanent-magnet synchronous motor (SPM), taking into account the effect of arbitrarily curved motor surfaces. We also studied the slotless configuration of the external rotor permanent-magnet motor for the purpose of calculating the complex relative air-gap permeance. The model is able to predict the air gap field and torque with high accuracy, which cannot be achieved using the previously available analytical methods in both cases: internal and external rotor permanent-magnet motor. We obtained one of the conformal mappings used in this study, the numerical solution of the Schwarz-Christoffel (SC) integral, by using the Matlab SC Toolbox. We used this field solution to calculate cogging torque and electromagnetic torque by integrating the Maxwell stress tensor inside the air gap. We verified the accuracy of the developed method by comparing its results with those obtained from the developed numerical finite-element (FE) model.

Analytical Analysis of Cage Rotor Induction Motors in Healthy, Defective, and Broken Bars Conditions

This paper presents a 2-D static analytical method in the frequency domain for the calculation of magnetic field distribution, eddy-currents, circuit model parameters, and steady-state performances in multiphase/multipole cage rotor induction motors with integer and fractional stator winding. The complex model allows to study the healthy, defective, and broken bars conditions in these electrical machines. The proposed static analytical model considers stator and rotor slotting with tooth-tips. The method is based on the resolution of Poissons, Laplaces, and Helmholtzs equations in stator slots, air-gap, and rotor bars regions, respectively. The electromagnetic torque is obtained from both the electrical equivalent circuit and Maxwell stress tensor that is given by the magnetic field calculation. The analytical results are validated by those issued from time harmonic finite-element method.

Neural network technique for induction motor rotor faults classification-dynamic eccentricity and broken bar faults-

This paper presents an artificial neural network (ANN) based technique to identify rotor faults in a three-phase induction motor. The main types of faults considered are broken bar and dynamic eccentricity. The feature extraction based on the frequency and the magnitude of the related fault components in the stator current spectrum is performed automatically by a Matlab script. Features with different speed and load levels are used as input for training a feedforward layered neural network. The laboratory results show that the proposed method is able to detect the faulty conditions with high accuracy and to separate between deferent types of faults.

Numerical analysis of brushless permanent magnet motors using Lagrange multiplier

In this paper we present a finite element method for analysis a brushless surface mounted permanent magnet motor with Lagrange multipliers for movement, dirichlet and anti-periodicity consideration.

Complex finite element analysis of a solid rotor induction motor

A method for predicting the steady state performance of a solid rotor induction motor using coupled non-linear complex finite elements is described. The principle of the model is to consider two starting times, /spl omega/ in the stator region and s/spl omega/ in the rotor region. The coupling between the rotor and the stator is achieved by two means using Lagrange multipliers at a suitable air-gap interface. A comparison between the experimental and the computed characteristics of a solid rotor induction motor is performed with interesting results.

Diagnosis of the AC Current Densities Effect on the Cathodic Protection Performance of the Steel X70 for a Buried Pipeline due to Electromagnetic Interference Caused by HVPTL

This paper diagnoses the effect of the AC current densities induced by the electromagnetic interferences between high voltage power line and buried power line on the cathodic protection performances of the X70 steel in the simulated soil. First, the induced voltage onto the pipeline was calculated for various power line configurations, separation distances between transmission line and pipeline and parallelism lengths. The induced AC current density was computed function to the induced voltage, soil resistivity, and holiday diameter. Then, the electrochemical characters of the X70 steel, at various AC current densities, are measured using the potentiodynamic method. The electrochemical parameters obtained by the electrochemical tests are used as boundary conditions in the cathodic protection simulation model. The results indicate that, under influence of AC current densities, the X70 steel is more susceptible to corrosion, and the cathodic protection is unable to maintain the protection potential.