The Experts below are selected from a list of 105381 Experts worldwide ranked by ideXlab platform
Maryam Mohammadi - One of the best experts on this subject based on the ideXlab platform.
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Unified Modeling Technique for Axially Uniform and Nonuniform Eccentricity Faults in Three-Phase Squirrel Cage Induction Motors
IEEE Transactions on Industrial Electronics, 2018Co-Authors: Mansour Ojaghi, Maryam MohammadiAbstract:Many mechanical faults cause Eccentricity in squirrel cage induction motors (SCIMs), so it is reasonable to design and implement reliable Eccentricity fault diagnosis systems for the SCIMs. Accurate modeling and simulation techniques help to reach this aim more easily. It is common to assume that the Eccentricity fault is uniform along the motor length when modeling and simulation that is often far from real situation. In this paper, experimental inspection is performed first to show that having the same severity of Eccentricity at one end of the motor, the axially nonuniform Eccentricity may produce lower fault indices than the axially uniform Eccentricity. Then, the two-dimensional (2-D) modified winding function theory is presented and used to obtain analytic expressions for various self-/mutual inductances of the stator windings and the rotor meshes and their derivatives versus the rotor position. The expressions are applicable under various axially uniform and nonuniform eccentricities as well as the healthy condition. Multiple coupled circuit model is used along with these expressions to develop a comprehensive analytic model for the SCIMs. Simulation results obtained by this model are in good agreement with corresponding experimental results and confirm accuracy of the attained modeling and simulation technique.
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Modeling Eccentricity faults with axial asymmetry in three-phase induction motors
IECON 2016 - 42nd Annual Conference of the IEEE Industrial Electronics Society, 2016Co-Authors: Mansour Ojaghi, Maryam MohammadiAbstract:Squirrel cage induction motors (SCIMs) have gained critical roles in many industries. Most mechanical faults cause Eccentricity within the SCIMs, so, it is important to develop reliable Eccentricity fault diagnosis systems. Modeling and simulation of the Eccentricity faults can help to reach this aim. This paper proposes modeling and simulation of the Eccentricity faults with variable degrees along the axial length of the induction motor. Multiple coupled circuits model with 2-D modified winding function theory are used for this purpose. Simulation results show that having the same risk of rubbing the stator by the rotor, the axially asymmetric Eccentricity (inclined Eccentricity) creates lower fault indices, so, considering the higher occurrence probability as well, it is reasonable to design the fault diagnosis systems based on the inclined eccentricities.
Mansour Ojaghi - One of the best experts on this subject based on the ideXlab platform.
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Unified Modeling Technique for Axially Uniform and Nonuniform Eccentricity Faults in Three-Phase Squirrel Cage Induction Motors
IEEE Transactions on Industrial Electronics, 2018Co-Authors: Mansour Ojaghi, Maryam MohammadiAbstract:Many mechanical faults cause Eccentricity in squirrel cage induction motors (SCIMs), so it is reasonable to design and implement reliable Eccentricity fault diagnosis systems for the SCIMs. Accurate modeling and simulation techniques help to reach this aim more easily. It is common to assume that the Eccentricity fault is uniform along the motor length when modeling and simulation that is often far from real situation. In this paper, experimental inspection is performed first to show that having the same severity of Eccentricity at one end of the motor, the axially nonuniform Eccentricity may produce lower fault indices than the axially uniform Eccentricity. Then, the two-dimensional (2-D) modified winding function theory is presented and used to obtain analytic expressions for various self-/mutual inductances of the stator windings and the rotor meshes and their derivatives versus the rotor position. The expressions are applicable under various axially uniform and nonuniform eccentricities as well as the healthy condition. Multiple coupled circuit model is used along with these expressions to develop a comprehensive analytic model for the SCIMs. Simulation results obtained by this model are in good agreement with corresponding experimental results and confirm accuracy of the attained modeling and simulation technique.
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Modeling Eccentricity faults with axial asymmetry in three-phase induction motors
IECON 2016 - 42nd Annual Conference of the IEEE Industrial Electronics Society, 2016Co-Authors: Mansour Ojaghi, Maryam MohammadiAbstract:Squirrel cage induction motors (SCIMs) have gained critical roles in many industries. Most mechanical faults cause Eccentricity within the SCIMs, so, it is important to develop reliable Eccentricity fault diagnosis systems. Modeling and simulation of the Eccentricity faults can help to reach this aim. This paper proposes modeling and simulation of the Eccentricity faults with variable degrees along the axial length of the induction motor. Multiple coupled circuits model with 2-D modified winding function theory are used for this purpose. Simulation results show that having the same risk of rubbing the stator by the rotor, the axially asymmetric Eccentricity (inclined Eccentricity) creates lower fault indices, so, considering the higher occurrence probability as well, it is reasonable to design the fault diagnosis systems based on the inclined eccentricities.
Subhasis Nandi - One of the best experts on this subject based on the ideXlab platform.
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Saturation independent detection of dynamic Eccentricity fault in salient-pole synchronous machines
2013 9th IEEE International Symposium on Diagnostics for Electric Machines Power Electronics and Drives (SDEMPED), 2013Co-Authors: T. Ilamparithi, Subhasis NandiAbstract:This paper proposes a novel scheme based on current signature analysis to estimate the severity of dynamic Eccentricity fault independent of saturation in salient-pole synchronous machines (SPSM). The detection technique uses short circuit test data and exploits the presence of inherent static Eccentricity in a machine. Implementation of the scheme involves two steps. First, the percentage increases in both mixed Eccentricity component and static Eccentricity component are computed. Then the difference between them is used as a factor to estimate the severity of dynamic Eccentricity. The method is also found capable of distinguishing between static and dynamic Eccentricity faults. Results obtained from an experimental 3 phase, 2.2 kW machine have been used to validate the proposed Eccentricity severity estimation scheme.
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Detection of Eccentricity Faults in Three-Phase Reluctance Synchronous Motor
IEEE Transactions on Industry Applications, 2012Co-Authors: Thirumarai Chelvan Ilamparithi, Subhasis NandiAbstract:Reluctance synchronous machines, particularly the newer ones with axially laminated anisotropic rotor, are being employed increasingly in many industrial applications as they offer energy efficient solutions along with low-cost rugged construction and zero speed regulation. High-performance requirements of the machine demand a high saliency ratio resulting in low air-gap length along the direct axis. Air-gap Eccentricity diagnosis therefore becomes very significant. In this paper, the effects of different types of Eccentricity faults in a commercially available reluctance synchronous motor (RSM) are first analyzed to identify the fault-specific frequency components in the line current spectrum. For validating the analyses, a modified-winding-function-based model and a finite-element-based model are built to simulate the motor under different Eccentricity conditions. Experiments are then carried out on a three-phase RSM with a moderate to high level of Eccentricity to confirm the theoretical prediction and simulation results. Finally, by applying residue-elimination technique, the effects of supply unbalance and internal asymmetry are minimized, and Eccentricity is detected very reliably. These results will help noninvasive Eccentricity fault detection in larger power salient-pole synchronous machines in the long run.
Fu Quan Zhao - One of the best experts on this subject based on the ideXlab platform.
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Analysis of influence of wheel Eccentricity on steering wheel shimmy
Zhongguo Gonglu Xuebao China Journal of Highway and Transport, 2011Co-Authors: Yun Shi Yao, Fang Wu Ma, Zhong Xu Feng, Hai Lin Wang, Fu Quan ZhaoAbstract:In order to enhance vehicle handling stability and traveling comfort, influence of wheel Eccentricity on steering wheel shimmy was discussed based on theoretical analysis and field vehicle test. Regarded level B vehicle as research object, comparison tests of prototype were carried out after analysis of steering wheel shimmy caused by eccentric forces of wheel and unbalance mass. Results show that compared with the dynamic balance adjustment of wheel, the bushing adjustment of swing-arm has more effect on steering wheel shimmy, but both of them can't obviously cut down vibrational acceleration amplitude. Wheel Eccentricity adjustment has significant influence on steering wheel shimmy. Vibrational acceleration amplitude cuts down around 2 times after wheel Eccentricity adjustment. Compared with unbalance mass, Eccentricity of wheel has more contribution on steering wheel shimmy and the steering wheel shimmy is improved by controlling wheel Eccentricity.
Yi Wu - One of the best experts on this subject based on the ideXlab platform.
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orbital cyclostratigraphy of the devonian frasnian famennian transition in south china
Palaeogeography Palaeoclimatology Palaeoecology, 2001Co-Authors: Yiming Gong, Chengyuan Wang, Baohua Li, Yi WuAbstract:Abstract Superbundlesets, bundlesets, bundles and laminae were formed in the carbonate successions of the Devonian Frasnian–Famennian transition in Guangxi, South China. Their hierarchical structures, ratio relationships and arrangement order within conodont zones are lasting and stable in the stratigraphical sequences, and can be traced across the different facies belts and sedimentary basins. The hierarchically organized superbundlesets, bundlesets, bundles and laminae correspond to a long Eccentricity, Eccentricity, obliquity and precession and sub-Milankovitch cyclothem, respectively. The ratio of long Eccentricity to Eccentricity is 1:4 below the boundary between Frasnian–Famennian and 1:3 above the boundary between Frasnian–Famennian, Eccentricity to obliquity is 1:3, and Eccentricity to precession is 1:6 in the Devonian. Since the Eccentricity periodicity of 100,000 years remains essentially steady through geological time, the periodicity of the long Eccentricity, obliquity, precession and sub-Milankovitch cycle was 400,000, 33,333, 16,667 and 8000 or 17,000 years. These ratios are different from those of the Permian, Cretaceous and Quaternary, and coincide well with those calculated theoretically by Berger et al. Science, 255 (1992) 560. This reinforces the hypothesis of the slowing of the earth's rotation and the lengthening of precession and obliquity periods since at least the Devonian time. On the basis of the hierarchical Milankovitch cyclothems, the chronostratigraphical subdivision and correlation of the Frasnian–Famennian transition can be made at the resolution of 100,000s and 10,000s of years. The duration of the upper rhenana Zone, linguiformis Zone, and lower, middle and upper triangularis Zone is 0.6, 0.8, 0.3, 0.3 and 0.3 Ma, respectively.
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Orbital cyclostratigraphy of the Devonian Frasnian–Famennian transition in South China
Palaeogeography Palaeoclimatology Palaeoecology, 2001Co-Authors: Yiming Gong, Chengyuan Wang, Baohua Li, Yi WuAbstract:Abstract Superbundlesets, bundlesets, bundles and laminae were formed in the carbonate successions of the Devonian Frasnian–Famennian transition in Guangxi, South China. Their hierarchical structures, ratio relationships and arrangement order within conodont zones are lasting and stable in the stratigraphical sequences, and can be traced across the different facies belts and sedimentary basins. The hierarchically organized superbundlesets, bundlesets, bundles and laminae correspond to a long Eccentricity, Eccentricity, obliquity and precession and sub-Milankovitch cyclothem, respectively. The ratio of long Eccentricity to Eccentricity is 1:4 below the boundary between Frasnian–Famennian and 1:3 above the boundary between Frasnian–Famennian, Eccentricity to obliquity is 1:3, and Eccentricity to precession is 1:6 in the Devonian. Since the Eccentricity periodicity of 100,000 years remains essentially steady through geological time, the periodicity of the long Eccentricity, obliquity, precession and sub-Milankovitch cycle was 400,000, 33,333, 16,667 and 8000 or 17,000 years. These ratios are different from those of the Permian, Cretaceous and Quaternary, and coincide well with those calculated theoretically by Berger et al. Science, 255 (1992) 560. This reinforces the hypothesis of the slowing of the earth's rotation and the lengthening of precession and obliquity periods since at least the Devonian time. On the basis of the hierarchical Milankovitch cyclothems, the chronostratigraphical subdivision and correlation of the Frasnian–Famennian transition can be made at the resolution of 100,000s and 10,000s of years. The duration of the upper rhenana Zone, linguiformis Zone, and lower, middle and upper triangularis Zone is 0.6, 0.8, 0.3, 0.3 and 0.3 Ma, respectively.
