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Electrical and Computer Engineering
Department of Electrical and Computer Engineering: Faculty Publications
- Keyword
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- Condition monitoring (3)
- Fault diagnosis (3)
- Sensorless control (3)
- Adaptive resampling (2)
- Buffer violation probability (2)
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- Classification (2)
- Current (2)
- Effective capacity (2)
- Energy storage (2)
- Interior permanent magnet synchronous machine (IPMSM) (2)
- Load management (2)
- Permanent magnet synchronous generator (PMSG) (2)
- Position estimation (2)
- Quality of service (QoS) constraints (2)
- Wind power generation (2)
- Adaptive observer (1)
- Adaptive support weights (1)
- Alignment free (1)
- Analog Harmonic Transform (1)
- Anisotropic optical materials (1)
- BER (1)
- BPAM (1)
- Ball bearings (1)
- Battery (1)
- Beam steering (1)
- Beamforming (1)
- Beampattern. (1)
- Bidding strategy (1)
- Bidirectional DC-DC converter (1)
- CUDA (1)
Articles 1 - 30 of 68
Full-Text Articles in Computer Engineering
Enhanced Optical Bistability With Film-Coupled Plasmonic Nanocubes, Christos Argyropoulos, Cristian Ciraci, David R. Smith
Enhanced Optical Bistability With Film-Coupled Plasmonic Nanocubes, Christos Argyropoulos, Cristian Ciraci, David R. Smith
Department of Electrical and Computer Engineering: Faculty Publications
Colloidally synthesized nanocubes strongly coupled to conducting films hold great promise for enhancing different nonlinear optical processes. They exhibit a robust and sensitive scattering response that can be easily controlled by their geometrical and material parameters. Strong local field enhancement is generated at the gap regions between the nanocubes and the metallic film. We show that strong optical bistability and all-optical switching behavior can be obtained by loading these nanogaps with Kerr nonlinear materials. Relatively low input intensities are required to obtain these nonlinear effects. The proposed design can lead to efficient, low-power, and ultrafast all-optical memories and scattering nanoswitches.
Multiplexed Fiber-Ring Laser Sensors For Ultrasonic Detection, Tongqing Liu, Lingling Hu, Ming Han
Multiplexed Fiber-Ring Laser Sensors For Ultrasonic Detection, Tongqing Liu, Lingling Hu, Ming Han
Department of Electrical and Computer Engineering: Faculty Publications
We propose and demonstrate a multiplexing method for ultrasonic sensors based on fiber Bragg gratings (FBGs) that are included inside the laser cavity of a fiber-ring laser. The multiplexing is achieved using add-drop filters to route the light signals, according to their wavelengths, into different optical paths, each of which contains a separate span of erbium-doped fiber (EDF) as the gain medium. Because a specific span of EDF only addresses a single wavelength channel, mode completion is avoided and the FBG ultrasonic sensors can be simultaneously demodulated. The proposed method is experimentally demonstrated using a two-channel system with two sensing …
Intensity-Demodulated Fiber-Ring Laser Sensor System For Acoustic Emission Detection, Ming Han, Tongqing Liu, Lingling Hu, Qi Zhang
Intensity-Demodulated Fiber-Ring Laser Sensor System For Acoustic Emission Detection, Ming Han, Tongqing Liu, Lingling Hu, Qi Zhang
Department of Electrical and Computer Engineering: Faculty Publications
We theoretically and experimentally demonstrate a fiber-optic ultrasonic sensor system based on a fiber-ring laser whose cavity consisting of a regular fiber Bragg grating (FBG) and a tunable optical band-pass filter (TOBPF). The FBG is the sensing element and the TOBPF is used to set the lasing wavelength at a point on the spectral slope of the FBG. The ultrasonic signal is detected by the variations of the laser output intensity in response to the cold-cavity loss modulations from the ultrasonicallyinduced FBG spectral shift. The system demonstrated here has a simple structure and low cost, making it attractive for acoustic …
Isolation Of High Quality Graphene From Ru By Solution Phase Intercalation, E. Koren, Eli A. Sutter, S. Bliznakov, F. Ivars-Barcelo, P. Sutter
Isolation Of High Quality Graphene From Ru By Solution Phase Intercalation, E. Koren, Eli A. Sutter, S. Bliznakov, F. Ivars-Barcelo, P. Sutter
Department of Electrical and Computer Engineering: Faculty Publications
2013 AIP Publishing LLC
Accuracy Improvement Of Quantitative Analysis By Spatial Confinement In Laser-Induced Breakdown Spectroscopy, L. B. Guo, Z. Q. Hao, M. Shen, W. Xiong, X. N. He, Z. Q. Xie, M. Gao, X. Y. Li, X. Y. Zeng, Yongfeng Lu
Accuracy Improvement Of Quantitative Analysis By Spatial Confinement In Laser-Induced Breakdown Spectroscopy, L. B. Guo, Z. Q. Hao, M. Shen, W. Xiong, X. N. He, Z. Q. Xie, M. Gao, X. Y. Li, X. Y. Zeng, Yongfeng Lu
Department of Electrical and Computer Engineering: Faculty Publications
To improve the accuracy of quantitative analysis in laser-induced breakdown spectroscopy, the plasma produced by a Nd:YAG laser from steel targets was confined by a cavity. A number of elements with low concentrations, such as vanadium (V), chromium (Cr), and manganese (Mn), in the steel samples were investigated. After the optimization of the cavity dimension and laser fluence, significant enhancement factors of 4.2, 3.1, and 2.87 in the emission intensity of V, Cr, and Mn lines, respectively, were achieved at a laser fluence of 42.9 J/cm2 using a hemispherical cavity (diameter: 5 mm). More importantly, the correlation coefficient of the …
Continuous Modulations Of Femtosecond Laserinduced Periodic Surface Structures And Scanned Line-Widths On Silicon By Polarization Changes, Weina Han, Lan Jiang, Xiaowei Li, Pengjun Liu, Le Xu, Yongfeng Lu
Continuous Modulations Of Femtosecond Laserinduced Periodic Surface Structures And Scanned Line-Widths On Silicon By Polarization Changes, Weina Han, Lan Jiang, Xiaowei Li, Pengjun Liu, Le Xu, Yongfeng Lu
Department of Electrical and Computer Engineering: Faculty Publications
Large-area, uniform laser-induced periodic surface structures (LIPSS) are of wide potential industry applications. The continuity and processing precision of LIPSS are mainly determined by the scanning intervals of adjacent scanning lines. Therefore, continuous modulations of LIPSS and scanned line-widths within one laser scanning pass are of great significance. This study proposes that by varying the laser (800 nm, 50 fs, 1 kHz) polarization direction, LIPSS and the scanned line-widths on a silicon (111) surface can be continuously modulated with high precision. It shows that the scanned line-width reaches the maximum when the polarization direction is perpendicular to the scanning direction. …
Formation Of Multiscale Surface Structures On Nickel Via Above Surface Growth And Below Surface Growth Mechanisms Using Femtosecond Laser Pulses, Craig A. Zuhlke, Troy P. Anderson, Dennis R. Alexander
Formation Of Multiscale Surface Structures On Nickel Via Above Surface Growth And Below Surface Growth Mechanisms Using Femtosecond Laser Pulses, Craig A. Zuhlke, Troy P. Anderson, Dennis R. Alexander
Department of Electrical and Computer Engineering: Faculty Publications
The formation of self-organized micro- and nano-structured surfaces on nickel via both above surface growth (ASG) and below surface growth (BSG) mechanisms using femtosecond laser pulse illumination is reported. Detailed stepped growth experiments demonstrate that conical mound-shaped surface structure development is characterized by a balance of growth mechanisms including scattering from surface structures and geometric effects causing preferential ablation of the valleys, flow of the surface melt, and redeposition of ablated material; all of which are influenced by the laser fluence and the number of laser shots on the sample. BSG-mound formation is dominated by scattering, while ASG-mound formation is …
Microfluidic Refractive Index Sensor Based On An All-Silica In-Line Fabry–Perot Interferometer Fabricated With Microstructured Fibers, Jiajun Tian, Yujie Lu, Qi Zhang, Ming Han
Microfluidic Refractive Index Sensor Based On An All-Silica In-Line Fabry–Perot Interferometer Fabricated With Microstructured Fibers, Jiajun Tian, Yujie Lu, Qi Zhang, Ming Han
Department of Electrical and Computer Engineering: Faculty Publications
We report a microfluidic fiber-optic refractive index (RI) sensor based on an in-line Fabry-Perot (FP) interferometer, which is formed by a silica tube sandwiched by two microstructured fibers (MFs). The sensor reported here can be fabricated at low cost, possess a robust structure, and has microfluidic capability. The micro-sized holes in the MFs naturally function as microfluidic channels through which liquid samples can be efficiently and conveniently delivered into and out of the FP cavity by a pressure/vacuum pump system for high-performance RI measurement. Due to the microfluidic capability enabled by the MFs, only sub microliter sample is required. We …
Distributed Fiber-Optic Laser-Ultrasound Generation Based On Ghost-Mode Of Tilted Fiber Bragg Gratings, Jiajun Tian, Qi Zhang, Ming Han
Distributed Fiber-Optic Laser-Ultrasound Generation Based On Ghost-Mode Of Tilted Fiber Bragg Gratings, Jiajun Tian, Qi Zhang, Ming Han
Department of Electrical and Computer Engineering: Faculty Publications
Active ultrasonic testing is widely used for medical diagnosis, material characterization and structural health monitoring. Ultrasonic transducer is a key component in active ultrasonic testing. Due to their many advantages such as small size, light weight, and immunity to electromagnetic interference, fiber-optic ultrasonic transducers are particularly attractive for permanent, embedded applications in active ultrasonic testing for structural health monitoring. However, current fiberoptic transducers only allow effective ultrasound generation at a single location of the fiber end. Here we demonstrate a fiber-optic device that can effectively generate ultrasound at multiple, selected locations along a fiber in a controllable manner based on …
Segmented Nanowires Displaying Locally Controllable Properties, Eli Anguelova Sutter, Peter Werner Sutter
Segmented Nanowires Displaying Locally Controllable Properties, Eli Anguelova Sutter, Peter Werner Sutter
Department of Electrical and Computer Engineering: Faculty Publications
Vapor-liquid-solid growth of nanowires is tailored to achieve complex one-dimensional material geometries using phase diagrams determined for nanoscale materials. Segmented one-dimensional nanowires having constant composition dis play locally variable electronic band structures that are deter mined by the diameter of the nanowires. The unique electrical and optical properties of the segmented nanowires are exploited to form electronic and optoelectronic devices. Using gold-germanium as a model system, in situ transmis sion electron microscopy establishes, for nanometer-sized Au Ge alloy drops at the tips of Ge nanowires (NWs), the parts of the phase diagram that determine their temperature dependent equilibrium composition. The …
Xing-Zone Bridge Construction For Multi-Hop Cognitive Radio Networks With Channel Bonding, Feng Ye, Yi Qian, Yaoqing Lamar Yang, Hamid Sharif
Xing-Zone Bridge Construction For Multi-Hop Cognitive Radio Networks With Channel Bonding, Feng Ye, Yi Qian, Yaoqing Lamar Yang, Hamid Sharif
Department of Electrical and Computer Engineering: Faculty Publications
Cognitive radio is an efficient technique to relieve the tense of wireless spectrum scarcity by allowing unlicensed secondary users (SUs) to access the licensed band opportunistically without causing interference to primary users (PUs). Although Federal Communications Commission (FCC) recently ruled that the data of PU activity schedule is accessible to SUs 24 hours ahead, which relieves SUs from heavy sensing or interruption by sudden PU activity, however, multi-hop wireless cognitive radio networks (MWCRN) suffers a unique problem caused by the fact that the spectrum resources are not unified in different areas affected by different PUs. In other words, an SU …
Binocular Video Object Tracking With Fast Disparity Estimation, Yun Ye, Song Ci, Yanwei Liu, Haohong Wang, Aggelos K. Katsaggelos
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 Survey On Smart Grid Communication Infrastructures: Motivations, Requirements And Challenges, Ye Yan, Yi Qian, Hamid Sharif, David Tipper
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 …
A Hierarchical Power Management Strategy For Multiple Single-Phase Roadway Microgrids, Yanping Jiao, Wei Qiao
A Hierarchical Power Management Strategy For Multiple Single-Phase Roadway Microgrids, Yanping Jiao, Wei Qiao
Department of Electrical and Computer Engineering: Faculty Publications
This paper proposes a centralized hierarchical power management strategy for multiple single-phase wind/solar generation-based roadway microgrids integrated into a threephase utility distribution grid. The proposed power management strategy consists of a Central Power Management Controller (CPMC) operating at the distribution grid level to regulate the power flow between the distribution grid and the microgrids, a Supervisory Power Management Controller (SPMC) operating at the microgrid level for voltage and frequency control of each microgrid under the coordination of the CPMC, and a Local Power Management Controller operating at the unit level for power management of each individual unit under the coordination …
Multi-Objective Design Optimization Of A Single-Sided Axial Flux Permanent Magnet Machine, Xu Yang, Dean Patterson, Jerry L. Hudgins
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.
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
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 …
Sizing Router Buffer For The Internet With Heterogeneous Tcp, Peng Yang, Ertong Zhang, Lisong Xu
Sizing Router Buffer For The Internet With Heterogeneous Tcp, Peng Yang, Ertong Zhang, Lisong Xu
Department of Electrical and Computer Engineering: Faculty Publications
The router buffer sizing problem is a vital problem to the performance of the Internet. The traditional rule-of-thumb is that the router buffer size should be equal to the bandwidthdelay product (BDP) of a link. Recent studies show that the router buffer size can be significantly smaller than the BDP without causing negative impact on the TCP performance in the Internet. But a fundamental assumption of all those studies is that all the TCP traffic in the Internet is generated by the traditional RENO protocol, which, however, is no longer true as the current Internet is dominated by multiple different …
Wind Turbine Fault Detection And Isolation Using Support Vector Machine And A Residual-Based Method, Jianwu Zeng, Dingguo Lu, Yue Zhao, Zhe Zhang, Wei Qiao, Xiang Gong
Wind Turbine Fault Detection And Isolation Using Support Vector Machine And A Residual-Based Method, Jianwu Zeng, Dingguo Lu, Yue Zhao, Zhe Zhang, Wei Qiao, Xiang Gong
Department of Electrical and Computer Engineering: Faculty Publications
This paper proposes a novel scheme combining support vector machines (SVM) and a residual-based method for wind turbine fault detection and isolation (FDI). SVMs with radius basis function kernels are used for detecting and identifying sensor stuck and offset faults, where binary codes of fault types are used as the outputs of the SVMs to minimize the number of SVMs being used. The same output of a SVM may correspond to different types of faults and the final decision is made by all SVMs instead of one SVM. Moreover, a residual-based fault detection method using a time-variant threshold is developed …
A Single-Switch Lcl-Resonant Isolated Dc-Dc Converter, Jianwu Zeng, Wei Qiao, Liyan Qu
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 …
A Multi-Camera Motion Capture System For Remote Health Care Monitoring, Yun Ye, Song Ci, Aggelos K. Katsaggelos, Yanwei Liu
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 …
An Isolated Three-Port Bidirectional Dc-Dc Converter For Photovoltaic Systems With Energy Storage, Jianwu Zeng, Wei Qiao, Liyan Qu
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
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
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
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 …
Stability And Dynamic Performance Improvement Of A Sensorless Ipmsm Drive Via Adaptive Estimated-Speed- Assisted Position Prediction And Current Quality Evaluation, Yue Zhao, Wei Qiao, Long Wu
Stability And Dynamic Performance Improvement Of A Sensorless Ipmsm Drive Via Adaptive Estimated-Speed- Assisted Position Prediction And Current Quality Evaluation, Yue Zhao, Wei Qiao, Long Wu
Department of Electrical and Computer Engineering: Faculty Publications
This paper studies stability issues of sensorless torque control of high power interior permanent magnet synchronous machines (IPMSMs) under large load transients, e.g., complete torque reversals with the highest slew rate allowed. To perform a sensorless vector control, a current model-based sliding-mode observer is utilized to estimate the rotor position. The correlation between current regulation quality and position estimation accuracy is theoretically studied and experimentally verified. Based on the correlation, the accuracy of position estimation can be evaluated online indirectly. Moreover, an adaptive estimated-speed-assisted position prediction (ESAPP) scheme is proposed to improve the stability and performance of the sensorless control …
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
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
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 …
On Physical Layer Security For Cognitive Radio Networks, Zhihui Shu, Yi Qian, Song Ci
On Physical Layer Security For Cognitive Radio Networks, Zhihui Shu, Yi Qian, Song Ci
Department of Electrical and Computer Engineering: Faculty Publications
In this article we explore the security issues on physical layer for cognitive radio networks. First we give an overview on several existing security attacks to the physical layer in cognitive radio networks. We then discuss the related countermeasures on how to defend against these attacks. We further investigate one of the most important physical layer security parameters, the secrecy capacity of a cognitive radio network, and study the outage probability of secrecy capacity of a primary user from a theoretical point of view. Furthermore, we present performance results for secrecy capacity and outage probability between a node and its …
Frequency Demodulation-Aided Condition Monitoring For Drivetrain Gearboxes, Dingguo Lu, Wei Qiao
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
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 …