The Detection and Suppression of Unbalanced Magnetic Pull in Wound Rotor Induction Motors Using Pole-Specific Search Coils and Auxiliary Windings

© 2017 IEEE. This paper puts forward a concept for measuring rotor eccentricity in a wound rotor induction machine. The analysis is fully developed in the theory section, then an experimental rig is described and measurements are taken. These are compared with the calculated values. Pole-specific search windings are necessary in a wound rotor machine, because standard sideband current measurement techniques are only valid for cage induction machines. The search coils can also be used to suppress unbalanced magnetic pull

Design and analysis of a claw pole permanent magnet motor with molded soft magnetic composite core

Soft magnetic composite (SMC) materials and SMC electromagnetic devices have undergone substantial development in the past decade. Much work has been conducted on designing and prototyping various types of electrical machine. However, the iron cores were often made by cutting existing SMC preforms that were formed by compacting SMC powder in simple cylinder or bar-shape molds, and the magnetic properties of the cores may deteriorate significantly during the cutting process. To investigate "industry production-ready" products, this paper presents the design and analysis of a claw-pole permanent magnet (PM) motor with a molded SMC core of low mass density to replace the existing induction motor in a dishwasher pump. The magnetic properties of the molded SMC core are measured and utilized in the motor design and analysis. Finite element analysis (FEA) of magnetic field is carried out to accurately determine key motor parameters, and an improved phase variable model is applied to predict the motor performance. Both parameter computation and performance prediction are validated by the experimental results on the prototype. © 2009 IEEE

Predicting the behavior of induction machine using motor-CAD and MATLAB packages

© 2018 IEEE. Design optimization of induction machines uses computer aided design. These machines are the most suitable choice for various and complex industrial applications and improved efficiency is a key point. Wound rotor induction machines have enjoyed a renascence as the generator in many commercial wind turbines. In this paper, both Motor-CAD and MATLAB packages are employed to predict the electromagnetic behavior of an induction machine during steady-state and transient-state. Finite element analysis of a three-phase, four-pole induction machine is carried by using Motor-CAD and MATLAB in order to complete the comparison. The graphical interfaces of Motor-CAD environment will be utilized to describe the machine geometry, winding harmonics, material properties, and air-gap flux. The predicted results are validated by the experiment. Power losses are calculated for the test machine, and then the results will be explained

Rotor fault analysis in a doubly-fed induction generator using impedance matrix technique

© 2017 IEEE. Condition monitoring is a standard method for scheduling maintenance and ensuring that catastrophic failures do not occur in industrial motors

Maximizing investment value of small-scale PV in a smart grid environment

© 2016 IEEE. Determining the optimal size and orientation of small-scale residential based PV arrays will become increasingly complex in the future smart grid environment with the introduction of smart meters and dynamic tariffs. However consumers can leverage the availability of smart meter data to conduct a more detailed exploration of PV investment options for their particular circumstances. In this paper, an optimization method for PV orientation and sizing is proposed whereby maximizing the PV investment value is set as the defining objective. Solar insolation and PV array models are described to form the basis of the PV array optimization strategy. A constrained particle swarm optimization algorithm is selected due to its strong performance in non-linear applications. The optimization algorithm is applied to real-world metered data to quantify the possible investment value of a PV installation under different energy retailers and tariff structures. The arrangement with the highest value is determined to enable prospective small-scale PV investors to select the most cost-effective system

Inductive Charging Coupler with Assistive Coils

© 2016 IEEE. A wireless charging system contains a high-frequency power source, a wireless transformer/coupler, a rectifier, and the load. The wireless transformer/coupler is the key element of the wireless charging system, and the power source and the rectifier design are all dependent on its design. For a two coil type wireless transformer, the maximum efficiency is limited by the coupling coefficient, which rapidly decreases with increasing distance between the primary and secondary coils. The four coil system is widely used in low-power applications, where the maximum power transfer operating point is away from the maximum efficiency point. This paper proposes an inductive charging coupler with small assistive coils, where the high power and maximum efficiency regions overlap

Electromagnetic optimal design of a linear induction motor in linear metro

An improved T-model equivalent circuit of a single-sided linear induction machine (SLIM) is proposed. The analysis utilizes a set of one-dimensional air gap flux linkage equations. The model takes longitudinal end and transversal edge effects into consideration. These have to account for primary terminal half-filled slots, secondary back-iron saturation and skin effect in the secondary conducting sheet. In the circuit, several coefficients are obtained by use of the dummy electric potential method in conjunction with consideration of the complex power equivalence between the primary and secondary sides. The coefficients derived include the longitudinal end effect coefficients K r and Kx, transversal edge effect coefficients C r and Cx, and skin effect coefficient Kf. The accuracy of the T-model is validated using comparison to a set of measured data under constant current - constant frequency conditions. These were taken from the Intermediate Capacity Transit System (ICTS) in Canada. An optimal design scheme for the SLIM is addressed. The application used for the optimization is a prototype propulsion system in a high temperature superconducting (HTS) maglev drive. The efficiency and primary weight are chosen as optimal objective functions while the thrust, power factor and other performance indexes are calculated. © 2010 IEEE

Instrucciones para los colaboradores

We study droplet coalescence in a molecular system with a variable viscosity and a colloid-polymer mixture with an ultralow surface tension. When either the viscosity is large or the surface tension is small enough, we observe that the opening of the liquid bridge initially proceeds at a constant speed set by the capillary velocity. In the first system we show that inertial effects become dominant at a Reynolds number of about 1.5+/- 0.5 and the neck then grows as the square root of time. In the second system we show that decreasing the surface tension by a factor of 10(5) opens the way to a more complete understanding of the hydrodynamics involved

Topological descriptors for 3D surface analysis

We investigate topological descriptors for 3D surface analysis, i.e. the classification of surfaces according to their geometric fine structure. On a dataset of high-resolution 3D surface reconstructions we compute persistence diagrams for a 2D cubical filtration. In the next step we investigate different topological descriptors and measure their ability to discriminate structurally different 3D surface patches. We evaluate their sensitivity to different parameters and compare the performance of the resulting topological descriptors to alternative (non-topological) descriptors. We present a comprehensive evaluation that shows that topological descriptors are (i) robust, (ii) yield state-of-the-art performance for the task of 3D surface analysis and (iii) improve classification performance when combined with non-topological descriptors.Comment: 12 pages, 3 figures, CTIC 201

The 1.1 angstrom resolution structure of a periplasmic phosphate-binding protein from Stenotrophomonas maltophilia: a crystallization contaminant identified by molecular replacement using the entire Protein Data Bank

During efforts to crystallize the enzyme 2,4-dihydroxyacetophenone dioxygenase (DAD) from Alcaligenes sp. 4HAP, a small number of strongly diffracting protein crystals were obtained after two years of crystal growth in one condition. The crystals diffracted synchrotron radiation to almost 1.0 Å resolution and were, until recently, assumed to be formed by the DAD protein. However, when another crystal form of this enzyme was eventually solved at lower resolution, molecular replacement using this new structure as the search model did not give a convincing solution with the original atomic resolution data set. Hence, it was considered that these crystals might have arisen from a protein impurity, although molecular replacement using the structures of common crystallization contaminants as search models again failed. A script to perform molecular replacement using MOLREP in which the first chain of every structure in the PDB was used as a search model was run on a multi-core cluster. This identified a number of prokaryotic phosphate-binding proteins as scoring highly in the MOLREP peak lists. Calculation of an electron-density map at 1.1 Å resolution based on the solution obtained with PDB entry 2q9t allowed most of the amino acids to be identified visually and built into the model. A BLAST search then indicated that the molecule was most probably a phosphate-binding protein from Stenotrophomonas maltophilia (UniProt ID B4SL31; gene ID Smal_2208), and fitting of the corresponding sequence to the atomic resolution map fully corroborated this. Proteins in this family have been linked to the virulence of antibiotic-resistant strains of pathogenic bacteria and with biofilm formation. The structure of the S. maltophilia protein has been refined to an R factor of 10.15% and an Rfree of 12.46% at 1.1 Å resolution. The molecule adopts the type II periplasmic binding protein (PBP) fold with a number of extensively elaborated loop regions. A fully dehydrated phosphate anion is bound tightly between the two domains of the protein and interacts with conserved residues and a number of helix dipoles