Jordi-Roger Riba Ruiz

Modeling of Surface-Mounted Permanent Magnet Synchronous Motors With Stator Winding Interturn Faults

This paper develops and analyzes a parametric model for simulating healthy and faulty surface-mounted permanent magnet synchronous motors. It allows studying the effects of stator winding interturn short-circuit faults. A relevant feature of the developed model is that it deals with spatial harmonics due to a nonsinusoidal rotor permanent magnet configuration. Additionally, the proposed model is valid for studying the behavior of these machines running under nonstationary conditions, including load or speed variations. Stator current spectra obtained from simulations performed by applying the proposed model show a close similitude with experimental results, highlighting the potential of such a model to understand the effects of stator winding failures on the current spectrum and allowing it to carry out an automatic diagnosis of such faults.

Detection of Demagnetization Faults in Permanent-Magnet Synchronous Motors Under Nonstationary Conditions

This paper presents the results of our study of the permanent-magnet synchronous motor (PMSM) running under demagnetization. We examined the effect of demagnetization on the current spectrum of PMSMs with the aim of developing an effective condition-monitoring scheme. Harmonics of the stator currents induced by the fault conditions are examined. Simulation by means of a two-dimensional finite-element analysis (FEA) software package and experimental results are presented to substantiate the successful application of the proposed method over a wide range of motor operation conditions. Methods based on continuous wavelet transform (CWT) and discrete wavelet transform (DWT) have been successfully applied to detect and to discriminate demagnetization faults in PMSM motors under nonstationary conditions. Additionally, a reduced set of easy-to-compute discriminating features for both CWT and DWT methods has been defined. We have shown the effectiveness of the proposed method by means of experimental results.

Feature Extraction of Demagnetization Faults in Permanent-Magnet Synchronous Motors Based on Box-Counting Fractal Dimension

This paper presents a methodology for feature extraction of a new fault indicator focused on detecting demagnetization faults in a surface-mounted permanent-magnet synchronous motors operating under nonstationary conditions. Preprocessing of transient-current signals is performed by applying Choi-Williams distribution to highlight the salient features of this demagnetization fault. In this paper, fractal dimension calculation based on the computation of the box-counting method is performed to extract the optimal features for diagnosis purposes. It must be noted that the applied feature-extraction process is autotuned, so it does not depend on the severity of the fault and is applicable to a wide range of operating conditions of the motor. The performance of the proposed system is validated experimentally. According to the obtained results, the proposed methodology is reliable and feasible for diagnosing demagnetization faults in industrial applications.

A Sensorless Method for Controlling the Closure of a Contactor

We propose a new closed-loop sensorless method for reducing contact bounce on closure of a contactor. Several approaches to the problem have already been described; most of them use some kind of sensor to establish the position and speed of the contacts in real time, whereas in our approach, the position and speed of the moving armature and contacts are calculated by using only the current and voltage values of the contactor coil as control inputs. A fuzzy controller takes as input the position and velocity of the armature and provides as output an intensity set point that controls the velocity of the closure of the contacts. Furthermore, we have developed a low-cost electronic module that implements the control system and integrates it in the contactor. The module eliminates the bounces completely and thus prevents the contacts from repeatedly making and breaking the circuit.

Comparative Study of Multivariate Methods to Identify Paper Finishes Using Infrared Spectroscopy

Recycled paper is extensively used worldwide. In the last decades, its market has expanded considerably. The increasing use of recycled paper in papermaking has led to the production of paper containing several types of impurities. Consequently, wastepaper mills are forced to implement quality control schemes for evaluating the incoming wastepaper stock, thus guarantying the specifications of the final product. The main objective of this work is to present a fast and reliable system for identifying different paper types. Therefore, undesirable paper types can be refused, improving the performance of the paper machine and the final quality of the paper manufactured. For this purpose, two fast techniques, i.e., Fourier transform midinfrared (FTIR) and reflectance near infrared (NIR), were applied to acquire the infrared spectra of the paper samples. Next, four processing multivariate methods, i.e., principal component analysis, canonical variate analysis (CVA), extended CVA (ECVA), and support vector machines (SVMs), were employed in the feature-extraction or dimension-reduction stage. Afterward, the k nearest neighbor (k NN) algorithm was used in the classification phase. Experimental results show the usefulness of the proposed methodology and the potential of both FTIR and NIR spectroscopic methods. Using the FTIR spectrum in association with SVM and kNN, the system achieved a maximum classification accuracy of 100%, whereas using the NIR spectrum in association with ECVA or SVM and kNN, the system achieved a maximum classification accuracy of 96.4%.

A Novel Parametric Model for AC Contactors

This paper develops a robust and fast parametric model to describe the dynamic behavior of an ac contactor. The model solves simultaneously the mechanical and electromagnetic coupled differential equations that govern its dynamic response. It deals with the shading rings and takes into account the fringing flux. Data from simulations carried out by applying the presented parametric model are compared with experimental data, demonstrating the models validity and effectiveness.

A Computer Model for Teaching the Dynamic Behavior of AC Contactors

Ac-powered contactors are extensively used in industry in applications such as automatic electrical devices, motor starters, and heaters. In this work, a practical session that allows students to model and simulate the dynamic behavior of ac-powered electromechanical contactors is presented. Simulation is carried out using a rigorous parametric model of the ac contactor that avoids simplification assumptions and is thoroughly explained. The goal of this practical is to introduce students to the topic of dynamic simulation of real devices. It covers both the transient and the steady-state response of the electromechanical system under study. The proposed methodology is flexible and not particularly time-consuming, and it allows the students easily to change the electromechanical constants of the contactor they are studying. The results of the simulations were compared with experimental data acquired by the students; a close similarity between real and simulated data was observed. The Technical University of Catalonia (UPC), Spain, has incorporated the simulation methodology proposed in this paper in a practical session of an electrical engineering course.

Sensorless Control and Fault Diagnosis of Electromechanical Contactors

This paper describes a novel algorithm for a closed-loop sensorless control of electromagnetic devices. It integrates a novel fault diagnosis algorithm of the whole electromagnetic circuit. Applied to a contactor with a dc core, it eliminates the armature and contact bounce, whether it is ac or dc powered and at either 50 or 60 Hz. The position and velocity of the moving armature and contacts are calculated by means of the online determination of the inductance using only the measured current and voltage values of the contactor coil as control inputs. A fuzzy controller takes the position and velocity of the armature as input and provides the current set point as output, which controls the velocity of closure of the contacts. The algorithm has been implemented in a low-cost electronic module.

Electric field effects of bundle and stranded conductors in overhead power lines

High‐voltage overhead power lines are a source of quasi‐static electric and magnetic fields and also of audible noise and electromagnetic interferences due to corona activity. Electrical engineers have the responsibility to design and to maintain such lines, so it is very important that they acquire sufficient knowledge about these subjects while they are studying. Bundle and stranded conductors modify the spatial distribution of the electric field generated by the power line and also affect the corona onset conditions. This article describes the implementation of a method that models the behavior of electric fields generated by any three‐phase power line. Different configurations of overhead power lines are analyzed. The proposed methodology has been contrasted with results from other authors and with available experimental data.

Magnetic field generated by sagging conductors of overhead power lines

This article describes the implementation of the equations that govern the behavior of magnetic fields generated by three‐phase power lines. From the equations obtained in this work, the profiles of the magnetic fields generated by different practical power lines configurations have been analyzed. Results from simulations have been contrasted with experimental data showing a close agreement between them. These values have been also compared with current international regulations showing that in all the situations their values fulfill the reference levels. Additionally, the effect of a conducting ground has been discussed. It has been proved that in practical cases the effects from the earth currents can be neglected as compared with effects from line currents. Furthermore special attention is paid to the catenary shape of overhead conductors. The magnetic field generated by sagging conductors has been calculated and compared with the one generated by straight equivalent conductors.