Electrical and Computer Engineering Commons^™

Imbalance Fault Detection Of Direct-Drive Wind Turbines Using Generator Current Signals, Xiang Gong, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

No abstract provided.

Short-Term Wind Power Prediction Using A Wavelet Support Vector Machine, Jianwu Zeng, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

No abstract provided.

Reliability-Driven Optimum Standby Electric Storage Allocation For Power Distribution Systems, Salman Kahrobaee, Sohrab Asgarpoor

Department of Electrical and Computer Engineering: Faculty Publications

Integration of distributed energy resources (DER) has become an indispensable aspect of the future smart grid. The significant and valuable impact of these resources is expected to lead toward a more reliable and efficient power system. As the number of distributed generation and storage systems increases, the availability of sensitive and critical loads may be improved by allocating a portion of electricity storage capacity as a reserve. The goal of this paper is to determine the optimum standby storage capacity in a smart grid based on reliability indices such as the Expected Interruption Cost (EIC) of the system using particle …

The Effect Of Demand Side Management On Reliability Of Automated Distribution Systems, Salman Kahrobaee, Sohrab Asgarpoor

Department of Electrical and Computer Engineering: Faculty Publications

Demand side management (DSM) provides power systems with the opportunity to supply electricity to the customers more efficiently and reliably. In a smart grid incorporating automated control and distributed energy systems, an effective DSM can alleviate the peak load and shift part of the demand to off-peak hours. This paper evaluates the impact of DSM on reliability of automated power distribution systems. Unlike the previous research studies, we perform load flow analysis and state enumeration to include actual restrictions of distribution systems such as voltage limits of buses and power flow limits of branches. The effects of demand curve and …

Real-Time Temporal Stereo Matching Using Iterative Adaptive Support Weights, Jedrzej Kowalczuk, Eric T. Psota, Lance C. Pérez

Department of Electrical and Computer Engineering: Faculty Publications

Stereo matching algorithms are nearly always designed to find matches between a single pair of images. A method is presented that was specifically designed to operate on sequences of images. This method considers the cost of matching image points in both the spatial and temporal domain. To maintain real-time operation, a temporal cost aggregation method is used to evaluate the likelihood of matches that is invariant with respect to the number of prior images being considered. This method has been implemented on massively parallel GPU hardware, and the implementation ranks as one of the fastest and most accurate real-time stereo …

A Survey Of Energy-Efficient Compression And Communication Techniques For Multimedia In Resource Constrained Systems, Tao Ma, Michael Hempel, Dongming Peng, Hamid Sharif

Department of Electrical and Computer Engineering: Faculty Publications

Advances in wireless multimedia communication technologies enable new types of pervasive and ubiquitous applications such as mobile health care, environmental monitoring, facility monitoring and traffic surveillance. Among different factors concerned, energy efficiency is one of the most challenging issues in multimedia communication due to the resource constraints, and the requirements for high bandwidth and low transmission delay. In this survey, we provide a broad picture of the state of- the-art energy efficient techniques that have been proposed in wireless multimedia communication for resource-constrained systems such as wireless sensor networks and mobile devices.

Following the essential stages required for multimedia communication, …

Design Considerations Of Switched Reluctance Motors With Bipolar Excitation For Low Torque Ripple Applications, Cong Ma, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

Switched reluctance motors (SRMs) have been applied to many applications over the past decades due to their simple structure, low cost, and robustness. The primary disadvantage of SRMs is the relatively high torque ripple. In this paper, the machine design is considered under a two-mode bipolar excitation to achieve the optimum performance of a mutually coupled switched reluctance motor (MCSRM) for low torque ripple applications. Geometrical design equations and practical challenges are investigated. In addition, a six-slot, tenpole (6/10) SRM with a six-phase winding configuration under the two-mode bipolar excitation is optimized by solving a multiobjective optimization problem using a …

Improved Microcontroller-Based Electronic Respiratory Training, Steven A. Parkison, Jay D. Carlson, Lance C. Pérez

Department of Electrical and Computer Engineering: Faculty Publications

Respiratory training is a critical component of many rehabilitation plans, including those of stroke patients. Many current respiratory training techniques lack efficient methods for quantifying progress and updating testing parameters. A previously-developed microcontroller-based device, designed in conjunction with clinicians at the Institute for Rehabilitation Science and Engineering at Madonna Rehabilitation Hospital, has demonstrated promising results. Here, a prototype of a revised device that is network connected and remoatly sends trial information is presented.\ The proposed device demonstrates enhanced functionality, while being smaller and using less power than the original prototype.

Effective Capacity Of Two-Hop Wireless Communication Systems, Deli Qiao, Mustafa Cenk Gursoy, Senem Velipasalar

Department of Electrical and Computer Engineering: Faculty Publications

A two-hop wireless communication link in which a source sends data to a destination with the aid of an intermediate relay node is studied. It is assumed that there is no direct link between the source and the destination, and the relay forwards the information to the destination by employing the decode-and-forward scheme. Both the source and intermediate relay nodes are assumed to operate under statistical quality of service (QoS) constraints imposed as limitations on the buffer overflow probabilities. The maximum constant arrival rates that can be supported by this two-hop link in the presence of QoS constraints are characterized …

Online Soc And Soh Estimation For Multicell Lithium-Ion Batteries Based On An Adaptive Hybrid Battery Model And Sliding-Mode Observer, Taesic Kim, Wei Qiao, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes an adaptive hybrid battery model-based high-fidelity state of charge (SOC) and state of health (SOH) estimation method for rechargeable multicell batteries. The hybrid battery model consists of an enhanced Coulomb counting algorithm for SOC estimation and an electrical circuit battery model. A variable-length sliding window least squares (VSWLS)-based online parameter identification algorithm is designed to estimate the electrical parameters of the electrical battery model, which are then used as the parameters of an adaptive discrete-time sliding-mode observer (ADSMO) for terminal and open-circuit voltage estimation of a battery cell. The error of the SOC estimated from the enhanced …

A Survey On Smart Grid Communication Infrastructures: Motivations, Requirements And Challenges, Ye Yan, Yi Qian, Hamid Sharif, David Tipper

Department of Electrical and Computer Engineering: Faculty Publications

A communication infrastructure is an essential part to the success of the emerging smart grid. A scalable and pervasive communication infrastructure is crucial in both construction and operation of a smart grid. In this paper, we present the background and motivation of communication infrastructures in smart grid systems. We also summarize major requirements that smart grid communications must meet. From the experience of several industrial trials on smart grid with communication infrastructures, we expect that the traditional carbon fuel based power plants can cooperate with emerging distributed renewable energy such as wind, solar, etc, to reduce the carbon fuel consumption …

Fea Estimation And Experimental Validation Of Solid Rotor And Magnet Eddy Current Loss In Single-Sided Axial Flux Permanent Magnet Machines, Xu Yang, Dean Patterson, Jerry Hudgins, Jessica Colton

Department of Electrical and Computer Engineering: Faculty Publications

The rotor and magnet loss in single-sided axial flux permanent magnet machines with non-overlapped windings is studied in this paper. FEA estimations of the loss are carried out using both 2-D and 3-D modeling. The rotor and magnet losses are determined separately for stator slot passing and MMF space harmonics from currents in the stator. The segregation of loss between the solid rotor plate and the magnet is addressed. The eddy current loss reduction by magnet segments is discussed as well. The prototype 24 slot/22 pole single-sided AFPMs, fabricated with both single layer and double layer windings are assembled. Methods …

Multi-Objective Design Optimization Of A Single-Sided Axial Flux Permanent Magnet Machine, Xu Yang, Dean Patterson, Jerry L. Hudgins

Department of Electrical and Computer Engineering: Faculty Publications

This paper presents an optimal design approach for a single-sided axial flux permanent magnet(AFPM) machine. A multi-objective differential evolution based optimization algorithm is implemented, which is to maximize the output torque density (Nm/kg) and efficiency. Design constraints including geometrical and operating limits are considered. Total of seven independent variables are employed in the design. Optimization results are compared with a prototype design.

Binocular Video Object Tracking With Fast Disparity Estimation, Yun Ye, Song Ci, Yanwei Liu, Haohong Wang, Aggelos K. Katsaggelos

Department of Electrical and Computer Engineering: Faculty Publications

This paper presents a binocular PTU (pan-tilt unit) camera video object tracking scheme using the MeanShift algorithm and the runtime disparity estimation. The proposed method is to accommodate the requirement of 3D content generation and accurate tracking in more advanced video surveillance applications. The disparity estimation process for each stereoscopic pair is formulated as an energy minimization problem. The iterative solution procedure is implemented in a course-to-fine manner. The estimated disparity is used to scale the tracking window by the MeanShift algorithm, i.e. the size of the tracking area is adjustable according to its inner disparity, and thus the moving …

A Multi-Camera Motion Capture System For Remote Health Care Monitoring, Yun Ye, Song Ci, Aggelos K. Katsaggelos, Yanwei Liu

Department of Electrical and Computer Engineering: Faculty Publications

This paper presents a multi-camera motion capture system aiming to provide caregivers with timely access to the patient's health status through mobile communication devices. The major components include video capture, object detection, video coding and transmission, error concealment, and video analysis. Our contribution is twofold. First, several novel ideas are developed, including fast object detection, and content-aware and adaptive video coding and transmission. Second, all components are seamlessly integrated in a unified optimization framework dedicated for online data transmission. In the scenario, the subject walked on a treadmill with four tripod cameras capturing the video from different viewpoints. After video …

A Single-Switch Lcl-Resonant Isolated Dc-Dc Converter, Jianwu Zeng, Wei Qiao, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

Isolated converters are desirable in the DC-DC power conversion applications where isolation and/or a large voltage step-up gain is needed. Traditional isolated DC-DC converters either utilize many switches to achieve high efficiency or use few switches which result in low efficiency. This paper proposes a new single-switch isolated DC-DC converter with a LCL-resonant circuit. The proposed isolated DC-DC converter has the advantages of not only using the least number of (i.e., one) switch, but also achieving zero-current switching (ZCS) and zero-voltage switching (ZVS) when the switch is turned on and off, respectively. Experimental results are provided to validate the theoretical …

An Isolated Three-Port Bidirectional Dc-Dc Converter For Photovoltaic Systems With Energy Storage, Jianwu Zeng, Wei Qiao, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a new isolated, three-port, bidirectional, DC-DC converter for simultaneous power management of multiple energy sources. The proposed converter has the advantage of using the least number of switches and soft switching of the main switch, which is realized by using a LCL-resonant circuit. The converter is capable of interfacing sources of different voltage-current characteristics with an isolated load. In this paper, one photovoltaic (PV) panel, one rechargeable battery, and an isolated load are interfaced by the proposed converter. Simulation and experimental results show that the proposed converter is capable of maximum power point tracking control for the …

A Discrete-Time Direct-Torque And Flux Control For Direct-Drive Pmsg Wind Turbines, Zhe Zhang, Yue Zhao, Wei Qiao, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a novel discrete-time direct-torque and flux control (DTFC) scheme for a permanent-magnet synchronous generator (PMSG) used in a variable-speed direct-drive wind power generation system. The proposed DTFC does not rely on machine parameters, such as the inductances and permanent-magnet flux linkage, while the main advantages of the DTC, e.g., fast dynamic response and no need of coordinate transform, are preserved. The stator flux linkage is estimated by an adaptive low-pass filter (LPF), in which a variable cutoff frequency is used. The adaptive LPF stator flux observer can achieve high estimation precision over a wide operating range of …

An Adaptive Quasi-Sliding-Mode Rotor Position Observer-Based Sensorless Control For Interior Permanent Magnet Synchronous Machines, Yue Zhao, Wei Qiao, Long Wu

Department of Electrical and Computer Engineering: Faculty Publications

Advantages such as parameter insensitivity and high robustness to system structure uncertainty make the sliding-mode observer (SMO) a promising solution for sensorless control of interior permanentmagnet synchronousmachines (IPMSMs). In practical industry applications, in order to utilize digital controllers and achieve comparable performance under a lower sampling frequency, a discrete-time or quasi-SMO (QSMO) is commonly used. However, because of the saliency of an IPMSM, the magnitude of the extended electromotive force (EMF) will change with load (torque and/or speed) variations, whichmakes it challenging for the QSMO to estimate the extended EMF accurately. Without proper observer parameters, a phase shift will be …

An Extended Flux Model-Based Rotor Position Estimator For Sensorless Control Of Interior Permanent Magnet Synchronous Machines, Yue Zhao, Zhe Zhang, Wei Qiao, Long Wu

Department of Electrical and Computer Engineering: Faculty Publications

Starting from the classical dynamic model of interior permanent magnet synchronous machines (IPMSMs) expressed in the stationary reference frame, this paper presents a mathematical model reconstruction process for IPMSMs, from which an extended flux-based IPMSM model is derived. Compared with the commonly used extended electromotive force-based model, the extended flux-based model has notable advantages of simpler model structure and less sensitive to machine parameter and speed variations. An extended flux model-based position estimator is then proposed for sensorless control of an IPMSM by utilizing a sliding-mode observer with a dynamic position compensator. The latter improves the dynamic performance and low-speed …

Sensorless Control Of Surface-Mounted Permanent-Magnet Synchronous Machines For Low-Speed Operation Based On High-Frequency Square-Wave Voltage Injection, Yue Zhao, Zhe Zhang, Cong Ma, Wei Qiao, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a high-frequency signal injection-based position estimation scheme for surface-mounted permanent-magnet synchronous machines (SPMSM) operating in the low-speed range. A square-wave voltage vector is injected in the estimated rotating reference frame. The rotor position information is then extracted from the envelopes of the resulting induced high-frequency currents in the stationary reference frame. The proposed position estimation method has almost no dependence on machine asymmetric properties and, therefore, is well suited for SPMSM applications. Simulation results are provided to verify the effectiveness of the proposed method from 1 Hz to 50 Hz electric fundamental frequency under all load conditions. …

Model Reference Adaptive System-Based Speed Estimators For Sensorless Control Of Interior Permanent Magnet Synchronous Machines, Yue Zhao, Wei Qiao, Long Wu

Department of Electrical and Computer Engineering: Faculty Publications

In this work, speed estimators are designed based on a model reference adaptive system (MRAS) for sensorless control of interior permanent magnet synchronous machines (IPMSMs). To provide better filtering performance and reduce the noise contents in the estimated speed, an adaptive line enhancer is proposed to work with a sliding-mode observer to provide an improved reference model for speed estimation. In addition, a heterodyning speed adaption scheme is proposed to replace the conventional speed adaption mechanism. The proposed MRASbased speed estimator has two different operating modes, which are suitable for generator- and motor-type applications, respectively. The effectiveness of the proposed …

Frequency Demodulation-Aided Condition Monitoring For Drivetrain Gearboxes, Dingguo Lu, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

Condition monitoring and fault diagnosis (CMFD) of drivetrain gearboxes has become a prominent challenge in assorted industries. Current-based diagnostic techniques have significant advantages over traditional vibration-based techniques in terms of accessibility, cost, implementation and reliability. This paper proposes a current-based, frequency demodulation-aided CMFD method for drivetrain gearboxes. A mathematical model is developed for a drivetrain consisting of a two-stage gearbox and a permanent magnet synchronous generator (PMSG), from which the characteristic frequencies of gearbox faults in the PMSG stator current are derived. An adaptive signal resampling method is proposed to convert the variable fault characteristic frequencies to constant values for …

Current-Based Fault Detection For Wind Turbine Systems Via Hilbert-Huang Transform, Dingguo Lu, Wei Qiao, Xiang Gong, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

Mechanical failures of wind turbines represent a significant cost in both repairs and downtime. Detecting incipient faults of wind turbine components permits maintenance to be scheduled and failed parts to be repaired or replaced before causing failures of other components or catastrophic failure of the system. This paper proposes a Hilbert-Huang transform (HHT)-based algorithm to effectively extract fault signatures in generator current signals for wind turbine fault diagnosis by using the HHT’s capability of accurately representing the instantaneous amplitude and frequency of nonlinear and nonstationary signals. A phase-lock-loop (PLL) method is integrated to estimate wind turbine rotating speed, which is …

Low-Power Analog Processing For Sensing Applications: Low-Frequency Harmonic Signal Classification, Daniel J. White, Peter E. Williams, Michael W. Hoffman, Sina Balkir

Department of Electrical and Computer Engineering: Faculty Publications

A low-power analog sensor front-end is described that reduces the energy required to extract environmental sensing spectral features without using Fast Fourier Transform (FFT) or wavelet transforms. An Analog Harmonic Transform (AHT) allows selection of only the features needed by the back-end, in contrast to the FFT, where all coefficients must be calculated simultaneously. We also show that the FFT coefficients can be easily calculated from the AHT results by a simple back-substitution. The scheme is tailored for low-power, parallel analog implementation in an integrated circuit (IC). Two different applications are tested with an ideal front-end model and compared to …

Fiber-Optic Refractometer Based On An Etched High-Q Π-Phase-Shifted Fiber-Bragg-Grating, Qi Zhang, Natale J. Ianno, Ming Han

Department of Electrical and Computer Engineering: Faculty Publications

We present a compact and highly-sensitive fiber-optic refractometer based on a high-Q π-phase-shifted fiber-Bragg-grating (πFBG) that is chemically etched to the core of the fiber. Due to the π phase-shift, a strong πFBG forms a high-Q optical resonator and the reflection spectrum features an extremely narrow notch that can be used for highly sensitivity refractive index measurement. The etched πFBG demonstrated here has a diameter of ~9.3 μm and a length of only 7 mm, leading to a refractive index responsivity of 2.9 nm/RIU (RIU: refractive index unit) at an ambient refractive index of 1.318. The reflection spectrum of the …

Optimal Receiver Antenna Location In Indoor Environment Using Dynamic Differential Evolution And Genetic Algorithm, Shu-Han Liao, Chien-Hung Chen, Chien-Ching Chiu, Min-Hui Ho, Tadeusz A. Wysocki, Beata J. Wysocki

Department of Electrical and Computer Engineering: Faculty Publications

Using the impulse responses of these multipath channels, the bit error rate (BER) performance for binary pulse amplitude modulation impulse radio ultra-wideband communication system is calculated. The optimization location of receiving antenna is investigated by dynamic differential evolution (DDE) and genetic algorithm (GA) to minimize the outage probability. Numerical results show that the performance for reducing BER and outage probability by DDE algorithm is better than that by GA.

Broadening The Cloaking Bandwidth With Non-Foster Metasurfaces, Pai-Yen Chen, Christos Argyropoulos, Andrea Alu

Department of Electrical and Computer Engineering: Faculty Publications

We introduce the concept and practical design of broadband, ultrathin cloaks based on non-Foster, negatively capacitive metasurfaces. By using properly tailored, active frequency-selective screens conformal to an object, within the realm of a practical realization, we show that it is possible to drastically reduce the scattering over a wide frequency range in the microwave regime, orders of magnitude broader than any available passive cloaking technology. The proposed active cloak may impact not only invisibility and camouflaging, but also practical antenna and sensing applications.

Terahertz Antenna Phase Shifters Using Integrally-Gated Graphene Transmission-Lines, Pai-Yen Chen, Christos Argyropoulos, Andrea Alu

Department of Electrical and Computer Engineering: Faculty Publications

We propose the concept and design of terahertz (THz) phase shifters for phased antenna arrays based on integrally- gated graphene parallel-plate waveguides (GPPWGs). We show that an active transmission-line may be realized by combining GPPWGs with double-gate electrodes, in which the applied gate voltage can control the guiding properties of the gated sections. This may enable the realization of THz electronic switches and tunable loaded-lines for sub mm-wave antenna systems. Based on these active components, we theoretically and numerically demonstrate several digital and analog phase shifter designs for THz frequencies, with a wide range of phase shifts and small return …

Negative Refraction, Gain And Nonlinear Effects In Hyperbolic Metamaterials, Christos Argyropoulos, Nasim Mohammadi Estakhri, Francesco Monticone, Andrea Alu

Department of Electrical and Computer Engineering: Faculty Publications

The negative refraction and evanescent-wave canalization effects supported by a layered metamaterial structure obtained by alternating dielectric and plasmonic layers is theoretically analyzed. By using a transmission-line analysis, we formulate a way to rapidly analyze the negative refraction operation for given available materials over a broad range of frequencies and design parameters, and we apply it to broaden the bandwidth of negative refraction. Our analytical model is also applied to explore the possibility of employing active layers for loss compensation. Nonlinear dielectrics can also be considered within this approach, and they are explored in order to add tunability to the …