Computer Engineering Commons^™

Condition Monitoring Of Squirrel-Cage Induction Motors Fed By Pwm-Based Drives Using A Parameter Estimation Approach, Behrooz Mirafzal, F. Fateh, Chia-Chou Yeh, Richard J. Povinelli, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

Abstract:

A rotor condition monitoring technique is presented in this paper based on a parameter estimation approach. In this technique, the stator currents, voltages and motor speed are used as the input signals, where the outputs will be the rotor's inductance, resistance and consequently rotor time constant. This approach is verified by simulation of two different induction motor cases. These simulations are buttressed by experimental data obtained for a 2-hp induction motor in the case of healthy as well as one, three and five rotor bar breakages. In these tests, the induction motor was energized from a PWM-based drive, in …

Micro-Switches With Sputtered Au, Aupd, Au-On-Aupt, And Auptcu Alloy Electric Contacts, Ronald A. Coutu Jr., P. E. Kladitis, R. Cortez, R. E. Strawser, Robert L. Crane

Electrical and Computer Engineering Faculty Research and Publications

This work is the first to report on a new analytic model for predicting micro-contact resistance and the design, fabrication, and testing of microelectromechanical systems (MEMS) metal contact switches with sputtered bi-metallic (i.e. gold (Au)-on-Au-platinum (Pt), (Au-on-Au-(6%)Pt)), binary alloy (i.e. Au-palladium (Pd), (Au-(2%)Pd)), and tertiary alloy (i.e. Au-Pt-copper (Cu), (Au-(5%)Pt-(0.5%)Cu)) electric contacts. The micro-switches with bi-metallic and binary alloy contacts resulted in contact resistance between 1-2 /spl Omega/ and, when compared to micro-switches with sputtered Au electric contacts, exhibited a 3.3 and 2.6 times increase in switching lifetime, respectively. The tertiary alloy exhibited a 6.5 times increase in switch lifetime …

A Comparison Of Micro-Switch Analytic, Finite Element, And Experimental Results, Ronald A. Coutu Jr., P. E. Kladitis, Lavern A. Starman, J. R. Reid

Electrical and Computer Engineering Faculty Research and Publications

Electrostatically actuated, metal contact, micro-switches depend on having adequate contact force to achieve desired, low contact resistance. In this study, higher contact forces resulted from overdriving cantilever beam style switches, after pull-in or initial contact, until the beam collapsed onto the drive or actuation electrode. The difference between initial contact and beam collapse was defined as the useful contact force range. Micro-switch pull-in voltage, collapse voltage, and contact force predictions, modeled analytically and with the CoventorWare finite element software package, were compared to experimental results. Contact resistance was modeled analytically using Maxwellian spreading resistance theory. Contact resistance and contact …

Selecting Metal Alloy Electric Contact Materials For Mems Switches, Ronald A. Coutu Jr., Paul E. Kladitis, Kevin D. Leedy, Robert L. Crane

Electrical and Computer Engineering Faculty Research and Publications

This paper presents a method for selecting metal alloys as the electric contact materials for microelectromechanical systems (MEMS) metal contact switches. This procedure consists of reviewing macro-switch lessons learned, utilizing equilibrium binary alloy phase diagrams, obtaining thin film material properties and, based on a suitable model, predicting contact resistance performance. After determining a candidate alloy material, MEMS switches were designed, fabricated and tested to validate the alloy selection methodology. Minimum average contact resistance values of 1.17 and 1.87 Ω were measured for micro-switches with gold (Au) and gold–platinum (Au–(6.3%)Pt) alloy electric contacts, respectively. In addition, 'hot-switched' life cycle test results …

Time Series Classification Using Gaussian Mixture Models Of Reconstructed Phase Spaces, Richard J. Povinelli, Michael T. Johnson, Andrew C. Lindgren, Jinjin Ye

Electrical and Computer Engineering Faculty Research and Publications

A new signal classification approach is presented that is based upon modeling the dynamics of a system as they are captured in a reconstructed phase space. The modeling is done using full covariance Gaussian mixture models of time domain signatures, in contrast with current and previous work in signal classification that is typically focused on either linear systems analysis using frequency content or simple nonlinear machine learning models such as artificial neural networks. The proposed approach has strong theoretical foundations based on dynamical systems and topological theorems, resulting in a signal reconstruction, which is asymptotically guaranteed to be a complete …

Application Of Bi-State Magnetic Material To Automotive Offset-Coupled Ipm Starter/Alternator Machine, Ayman M. El-Refaie, Russell Manzke, Thomas M. Jahns

Electrical and Computer Engineering Faculty Research and Publications

This paper investigates a new approach to designing high-speed interior permanent-magnet (IPM) synchronous machines using a bi-state soft magnetic material. The bi-state material can have its normally high magnetic permeability permanently reduced in localized regions to that of air by means of heat treatment. This new work significantly expands a previous investigation by considering offset-coupled IPM machines that make it possible to significantly increase the rotor speed while retaining all of the other specifications of the 6-kW starter/alternator application. Lumped-parameter models, Monte Carlo optimization, and both electromagnetic and structural finite-element analysis are used to develop new offset-coupled IPM machine designs …

Induction Machine Broken-Bar Fault Diagnosis Using The Rotor Magnetic Field Space-Vector Orientation, Behrooz Mirafzal, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

A new technique based on rotor magnetic field space vector orientation is presented to diagnose broken-bar faults in induction machines operating at steady state. In this technique, stator currents and voltages are used as inputs to compute and subsequently observe the rotor magnetic field orientation, which has a more significant "swing-like" pendulous oscillation in case of broken-bar faults than in healthy operation. It will be shown here that the range of this "pendulous oscillation" is a function of the number of broken bars. Also in this technique, it was found that an inter-turn shorted stator-winding fault, which exhibits similar pendulous …

Optimal Calibration Of Pet Crystal Position Maps Using Gaussian Mixture Models, Kelly A. Stronger, Michael T. Johnson

Electrical and Computer Engineering Faculty Research and Publications

A method is developed for estimating optimal PET gamma-ray detector crystal position maps, for arbitrary crystal configurations, based on a binomial distribution model for scintillation photon arrival. The approach is based on maximum likelihood estimation of Gaussian mixture model parameters using crystal position histogram data, with determination of the position map taken from the posterior probability boundaries between mixtures. This leads to minimum probability of error crystal identification under the assumed model.

Optimized Breakdown Probabilities In Al/Sub 0.6/Ga/Sub 0.4/As-Gaas Heterojunction Avalanche Photodiodes, Oh-Hyun Kwon, Majeed M. Hayat, Joe C. Campbell, Bahaa E.A. Saleh, Malvin Carl Teich

Electrical and Computer Engineering Faculty Research and Publications

Recently, it has been shown that the noise characteristics of heterojunction Al/sub 0.6/Ga/sub 0.4/As-GaAs avalanche photodiodes (APDs) can be optimized by proper selection of the width of the Al/sub 0.6/Ga/sub 0.4/As layer. Similar trends have also been shown theoretically for the bandwidth characteristics. The resulting noise reduction and potential bandwidth enhancement have been attributed to the fact that the high bandgap Al/sub 0.6/Ga/sub 0.4/As layer serves to energize the injected electrons, thereby minimizing their first dead space in the GaAs layer. We show theoretically that the same optimized structures yield optimal breakdown-probability characteristics when the APD is operated in Geiger …

Effect Of Stochastic Dead Space On Noise In Avalanche Photodiodes, Oh-Hyun Kwon, Majeed M. Hayat, Joe C. Campbell, Bahaa E.A. Saleh, Malvin Carl Teich

Electrical and Computer Engineering Faculty Research and Publications

A stochastic dead-space model for impact ionization is developed and used to study the effect of the soft nature of the ionization capability of carriers on the excess noise factor of avalanche photodiodes. The proposed model is based on the rationale that the gradual, or soft, transition in the probability density function (PDF) for the distance from birth to impact ionization can be viewed as that resulting from uncertainty in the dead space itself. The resulting soft PDF, which is parameterized by a tunable softness parameter, is used to establish the limitations of the existing hard-threshold ionization models in ultrathin …