A High-Fidelity Computationally Efficient Transient Model of Interior Permanent-Magnet Machine With Stator Turn Fault

An accurate transient model of interior permanent-magnet (IPM) machine with stator turn fault with due account of magnetic saturation is essential to develop robust and sensitive interturn fault detection algorithms and to evaluate drive controller performance and stability under fault conditions. This paper proposes a general method of modeling stator turn fault using flux linkage map of IPM machine under fault extracted from finite-element (FE) analysis. Simulation results from the proposed fault model are compared against FE and experimental results. The results show that the proposed model matches well with experimental data

A Nine-Phase 18-Slot 14-Pole Interior Permanent Magnet Machine with Low Space Harmonics for Electric Vehicle Applications

© 1986-2012 IEEE.One of the key challenges of utilizing concentrated winding in interior permanent magnet machines (IPMs) is the high rotor eddy current losses in both magnets and rotor iron due to the presence of a large number of lower and higher order space harmonics in the stator magnetomotive force (MMF). These MMF harmonics also result in other undesirable effects, such as localized core saturation, acoustic noise, and vibrations. This paper proposes a nine-phase 18-slot 14-pole IPM machine using the multiple three-phase winding sets to reduce MMF harmonics. All the subharmonics and some of the higher order harmonics are cancelled out, while the advantages of the concentrate windings are retained. The proposed machine exhibits a high efficiency over wide torque and speed ranges. A 10-kW machine prototype is built and tested in generator mode for the experimental validation. The experimental results indicate the effectiveness of the MMF harmonics cancellation in the proposed machine

Spray‐pyrolyzed Cd‐substituted kesterite thin‐films for photovoltaic applications: Post annealing conditions and property studies

Kesterite materials were investigated for their suitability as absorber layers for thin-film photovoltaic cells. Thin- films of copper cadmium zinc tin sulfide (Cu2CdxZn1-xSnS4) were prepared by spray pyrolysis on soda-lime glass. The obtained thin-films were subjected to post annealing treatment at 525 ◦C in a sulfur atmosphere to study the effects on morphology, stoichiometry, phase formation and optical properties by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and ultraviolet visible spectroscopy (UV–Vis). The XRD patterns revealed the presence of prominent kesterite peaks in the unannealed and annealed thin-films, with enhanced crystallinity in the annealed thin-films. The crystal sizes of the unannealed and annealed thin-films were estimated from the XRD data and ranged from 5 nm to 27 nm for unannealed thin-films and 13 nm–25 nm for annealed thin-films. The unannealed thin-films exhibited a non-uniformly shaped morphology, which was a mixture of cube-shaped and rod-shaped nanoparticles, while the annealed thin-films exhibited a uniformly shaped morphology of flake-shaped nanoparticles, indicating enhanced crystallinity

Student experiences of practical activities during the COVID-19 pandemic

During the COVID-19 pandemic practical activities for undergraduate students have been severely disrupted. Activities in the field of computing, control, electrical and electronic engineering at the University of Sheffield have been taught during the autumn term of 2020/2021 academic year through socially distanced in-lab sessions, remote access to in-lab equipment, take-home kits, and other online methods. Students were asked to leave feedback for each activity using an anonymous online questionnaire, designed to capture their perceptions on their learning experience. Based on the responses received, a number of recommendations have been formulated to help practical educators make decisions on the modes of delivery of certain activities and for certain student cohorts, when pivoting to increased distance learning. Students indicated they would prefer to conduct some activities using take-home kits in the future, paving the way for beneficial long-term changes to the delivery of some practical activities beyond the times of the pandemic

Thermal analysis and control development of interior PM traction machines

The paper presents thermal analysis and control development for interior permanent magnet (IPM) traction machine. Losses of the IPM traction machine are discussed and derived using measurement and finite element analysis. The loss components are then employed for steady-state and transient thermal analysis. Assuming rotor temperature obtained from transient thermal simulation over driving cycles, dq-axis current reference LUTs employing on the traction machine drive system are determined. It is shown that when steady state rotor temperature is higher than the average driving cycle temperature, maximum difference in electromagnetic torque is less than 5.5% over the torque-speed envelope

Assessment of Multivessel Coronary Artery Disease Using Cardiovascular Magnetic Resonance Pixelwise Quantitative Perfusion Mapping

OBJECTIVES: The authors sought to compare the diagnostic accuracy of quantitative perfusion maps to visual assessment (VA) of first-pass perfusion images for the detection of multivessel coronary artery disease (MVCAD). BACKGROUND: VA of first-pass stress perfusion cardiac magnetic resonance (CMR) may underestimate ischemia in MVCAD. Pixelwise perfusion mapping allows quantitative measurement of regional myocardial blood flow, which may improve ischemia detection in MVCAD. METHODS: One hundred fifty-one subjects recruited at 2 centers underwent stress perfusion CMR with myocardial perfusion mapping, and invasive coronary angiography with coronary physiology assessment. Ischemic burden was assessed by VA of first-pass images and by quantitative measurement of stress myocardial blood flow using perfusion maps. RESULTS: In patients with MVCAD (2-vessel [2VD] or 3-vessel disease [3VD]; n = 95), perfusion mapping identified significantly more segments with perfusion defects (median segments per patient 12 [interquartile range (IQR): 9 to 16] by mapping vs. 8 [IQR: 5 to 9.5] by VA; p < 0.001). Ischemic burden (IB) measured using mapping was higher in MVCAD compared with IB measured using VA (3VD mapping 100 % (75% to 100%) vs. first-pass 56% (38% to 81%) ; 2VD mapping 63% (50% to 75%) vs. first-pass 41% (31% to 50%); both p < 0.001), but there was no difference in single-vessel disease (mapping 25% (13% to 44%) vs. 25% (13% to 31%). Perfusion mapping was superior to VA for the correct identification of extent of coronary disease (78% vs. 58%; p < 0.001) due to better identification of 3VD (87% vs. 40%) and 2VD (71% vs. 48%). CONCLUSIONS: VA of first-pass stress perfusion underestimates ischemic burden in MVCAD. Pixelwise quantitative perfusion mapping increases the accuracy of CMR in correctly identifying extent of coronary disease. This has important implications for assessment of ischemia and therapeutic decision-making

Microscopy-BIDS: An extension to the brain imaging data structure for microscopy data

The Brain Imaging Data Structure (BIDS) is a specification for organizing, sharing, and archiving neuroimaging data and metadata in a reusable way. First developed for magnetic resonance imaging (MRI) datasets, the community-led specification evolved rapidly to include other modalities such as magnetoencephalography, positron emission tomography, and quantitative MRI (qMRI). In this work, we present an extension to BIDS for microscopy imaging data, along with example datasets. Microscopy-BIDS supports common imaging methods, including 2D/3D, ex/in vivo, micro-CT, and optical and electron microscopy. Microscopy-BIDS also includes comprehensible metadata definitions for hardware, image acquisition, and sample properties. This extension will facilitate future harmonization efforts in the context of multi-modal, multi-scale imaging such as the characterization of tissue microstructure with qMRI