The paper’s primary focus is on the monitoring of vibration signals and introduces an innovative method for the detection of bearing faults in electric machines WTMP. While conventional techniques based on vibration signals are popular in identifying the characteristic frequencies associated with faults, they encounter difficulties when dealing with signals that vary over time (non-stationary signals). To tackle this challenge, the proposed approach combines three distinct techniques: Continuous Wavelet Transform (CWT), Wavelet Packet Transform (WPT), and Matrix Pencil (MP). This hybrid method has several objectives: It aims to reconstruct signals that exhibit non-stationary behavior, emphasize the frequency related to bearing faults, and ultimately enhance the accuracy of fault detection. By harnessing the unique strengths of CWT, WPT, and MP, this proposed approach significantly improves the effectiveness of condition monitoring in electric machines, particularly in the context of detecting bearing faults. To validate the method’s performance, an experimental setup has been established. This setup allows for testing under various load conditions, offering a comprehensive assessment of the capabilities of the proposed technique. This rigorous experimental testing ensures the method's reliability and practical applicability in real-world scenarios.

Non-stationary fault detection under bearing fault operation of induction motor is investigated in this paper. For this aim, the vibration signal is analyzed by wavelet method and pencil matrix method. The pencil matrix (PM) or (MP) method has been combined with wavelet transform (WT), in order to reconstruct the non-stationary signal and detect the bearing fault frequency. For validation of results, an experimental setup is used for an induction motor under different load operation and with failure on its inner race. The application of the proposed technique on vibration signal under non-stationary state show that fault can be characterized by a particular signature that it is not possible with fast Fourier transform (FFT).

This paper presents an analytical approach to modelling radial magnetic force acting on stator surface of induction motors, this model covering the most important causes of magnetic noise such as saturation, eccentricity, slots and winding distribution. The study of magnetic noise due to eccentricity is given, which demonstrate the adverse effect of this phenomena, often occurring due to production inaccuracies.

This work illustrates a method to detect and separate the broken rotor bars (BRBs) from load torque oscillations (LTOs) in motor’s line current signature. The LTOs (due to mechanical load condition abnormalities, load fluctuations like speed reduction couplings or a defective transmission) can introduce similar symptoms as the rotor cage breaks do. The proposed policy is based on the set of two rotating coordinates (same and inverse angular velocity as the current’s fundamental frequency ω) for the stator current vector, and its decomposition into positive and negative components. The extracted components of the positive sequence allow to separate the similar effects produced by rotor defects and the oscillating load . The detection and separation process is performed through the demodulation of the amplitude modulating signal due to BRBs and the phase modulating signal due to LTOs. An experimental test bench has been conducted to validate the simulation results and demonstrate the effectiveness of the proposed approach.

This paper investigates the online detection of bearing fault by a vibration monitoring technique. A theoretical mechanical model for faults in bearing elements was developed. This model which is based on the nonlinear contact theory calculates the vibration of the shaft due to a defect in the ball bearing's rolling elements. An experimental device was also installed to validate the theoretical model in which one bearing of an induction motor was drilled on its outer race. The analyses of measured vibration show that defect can be characterized by a particular signature in vibration spectrum.

This paper describes an electromechanical model for bearing fault modeling and detection in Permanent Magnet Synchronous Motors. Bearing problems are one major cause for drive failure. Their detection is possible by vibration monitoring of characteristic bearing frequencies. In the new approaches proposed in this work, the vibrations of the rotor shaft due to bearing failure are calculated by solving Hertz's equation contact numerically. This vibrations leads to load torque variations. The spectral analysis of the Park's vector modulus shows the possibility of the model to detect bearing faults.

Vibrations and noise in electrical machines are directly related to the characteristics of the radial forces on one hand, and mechanical behavior on the other The characteristics of these forces depend on the cur gap flux density, and they are influenced by other factors such as stator slots and poles, saturation level, winding type and certain faults The aim of this work is to investigate the effect of eccentricity faults on electromagnetic noise generated by the external surface of PM synchronous machine (PMSM) For this purpose an analytical electromagnetic vibroacoustic model is developed. The results confirm the effect of eccentricity fault in generating some low modes radial forces An experimental device is being installed to validate the results of the analytical model Copyright (C) 2010 Praise Worthy Prize S.r.l. - All rights reserved.

This paper describes electromagnetic (EM) phenomena in plasma torches systems with and without plasma, at atmospheric pressure. Steady fluid flow and temperature equations are simultaneously solved (direct method) using a finite elements formulation for optically thin argon plasmas under the assumptions of local thermodynamic equilibrium (LTE) and laminar flow. The electromagnetic field equations are formulated in terms of potential vector. The governing magnetohydrodynamics (MHD) equations for an inductive plasma flow under LTE are presented, appropriate boundary conditions are given, and nonlinear parameters, such as the thermal and electrical conductivity of the gas and input power used in the simulation, are detailed.

This paper deals with faults in permanent magnet machines used in the traction chain of electrical and hybrid vehicles. First a state of the art is presented on the most encountered faults in these motors: that is permanent magnet demagnetisation, rotor eccentricity and short-circuits of stator windings. Then, an overview of electromagnetic and mechanical signatures of these faults is exposed through some simulation results about a permanent magnet synchronous motor. The developed models can be suitably used in diagnosis operations.

Vibration and noise in permanent magnet synchronous machine (PMSM) are directly related to the characteristics of the magnetic radial forces and mechanical behaviors of the machine. The radial forces dependent on the distribution of the flux density in the air gap region of the machine. These forces are influenced by the natural aspects of the PMSM such as rotor and stator slots, saturations and winding type but also on the health state of the machine as for example the eccentricity. The aim of this work is to study the effect of eccentricity on radial forces in PMSM. For this purpose an analytical and numerical model for calculating radial force taking into account eccentricity are developed. Thus an experimental test bench has been developed to validate the proposed model in the case of a dynamic eccentricity fault.

A 2D nonlinear model for the simulation of inductively coupled plasma torches (ICPTs) working at atmospheric pressure is presented, steady fluid flow and temperature equations are simultaneously solved using a finite elements formulation for optically thin argon plasmas under the assumptions of local thermodynamic equilibrium (LTE) and laminar flow. The electromagnetic field equations formulated in terms of vector potential. The governing resistive MHD equations for an inductive plasma flow under LTE are presented and appropriate boundary conditions are given and the parameters nonlinear such as the thermal and electrical conductivity of the gas and input power used in the simulations.