Influence of the Lamination Material and Rotor Pole Geometry on the Performance of Wound Field Synchronous Machines

This paper examines the influence of the lamination material and rotor pole geometry on the steady-state performance of a wound field synchronous machine operated in the generating mode. The investigations are carried out through 2D finite element analyses using a commercial software package. Non-Oriented silicon-iron alloys of various grades are selected to recognize the impact of their magnetic properties on the machine performance. Different methods for the extrapolation of BH curves from low medium field levels to saturation are reviewed and compared. The effect of using different materials on both the rotor and the stator core is assessed in terms of variation of the air gap power, the torque ripple and the core losses. The performance of a new machine featuring a higher-grade lamination material and a refined rotor pole geometry are compared at constant air gap power with those of the reference machine. The results show that, depending on the adopted strategy, it is possible to almost halve the torque ripple and slightly decrease the mass of the rotor core

A Contralateral Eye Study Comparing Corneal Biomechanics in Subjects with Bilateral Keratoconus with Unilateral Vogt’s Striae

The aim of this study was to analyze and compare corneal biomechanics in patients with bilateral keratoconus (KCN) with unilateral Vogt’s striae. In this prospective contralateral study, visual acuity, refraction, and corneal biomechanical parameters were evaluated in patients with bilateral KCN with unilateral Vogt’s striae using the Ocular Response Analyzer (ORA) (Reichert Inc., Buffalo, NY) and Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany). All patients underwent a comprehensive ophthalmic examination, including uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refraction (calculated by vectorial analysis), slit-lamp biomicroscopy, and Scheimpflug-based tomography. The patients enrolled in this study had a reliable diagnosis of bilateral clinical KCN with unilateral Vogt’s striae based on slit-lamp signs as well as corneal topographic/tomographic maps.  Fifty patients aged 18 to 40 years were included in this study. There was a significant difference in all clinical (distance visual acuity and refraction) and corneal biomechanical parameters between KCN eyes with and without unilateral Vogt’s striae (all P < 0.05). However, there were no significant differences in peak distance (P = 0.291), corneal compensated intraocular pressure (IOPCC) (P = 0.08), and J45 (P = 0.131) between the two groups. Most corneal biomechanical parameters, except for peak distance, IOPCC, and J45, showed a significant difference between KCN eyes with and without unilateral Vogt’s striae. Vogt’s striae may cause corneal biomechanical deterioration. This information could be used in clinical practice.Â

A Contralateral Eye Study Comparing Corneal Biomechanics in Subjects with Bilateral Keratoconus with Unilateral Vogt’s Striae

The aim of this study was to analyze and compare corneal biomechanics in patients with bilateral keratoconus (KCN) with unilateral Vogt’s striae. In this prospective contralateral study, visual acuity, refraction, and corneal biomechanical parameters were evaluated in patients with bilateral KCN with unilateral Vogt’s striae using the Ocular Response Analyzer (ORA) (Reichert Inc., Buffalo, NY) and Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany). All patients underwent a comprehensive ophthalmic examination, including uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refraction (calculated by vectorial analysis), slit-lamp biomicroscopy, and Scheimpflug-based tomography. The patients enrolled in this study had a reliable diagnosis of bilateral clinical KCN with unilateral Vogt’s striae based on slit-lamp signs as well as corneal topographic/tomographic maps.  Fifty patients aged 18 to 40 years were included in this study. There was a significant difference in all clinical (distance visual acuity and refraction) and corneal biomechanical parameters between KCN eyes with and without unilateral Vogt’s striae (all P < 0.05). However, there were no significant differences in peak distance (P = 0.291), corneal compensated intraocular pressure (IOPCC) (P = 0.08), and J45 (P = 0.131) between the two groups. Most corneal biomechanical parameters, except for peak distance, IOPCC, and J45, showed a significant difference between KCN eyes with and without unilateral Vogt’s striae. Vogt’s striae may cause corneal biomechanical deterioration. This information could be used in clinical practice.

Determination of 8 Synthetic Food Dyes by Solid Phase Extraction and Reversed-Phase High Performance Liquid Chromatography

Purpose: To develop a simple, selective, and sensitive extraction and assay method for the analysis of eight food dyes.Methods: All sulphonated colors were extracted by an NH2-aminopropyl-modified silica SPE cartridge, and thereafter determined by reverse phase high performance liquid chromatography (RP-HPLC) using a C18 column with gradient elution of ammonium acetate buffer (pH 6.7), methanol, and acetonitrile. The analysis was carried out on a UV detector with two optimized method settings within 17 min.Results: Certificated standard material (CRM) was used to validate the method, and significant difference was not observed between the results and assigned values. Maximum LOD was 1.154 ppm at 250 nm for Brilliant blue, and 0.873 ppm for carmoisine. Recovery was 94.2 % for Brilliant blue in jelly powder.Conclusion: This method was successfully applied to determine colorants in various (30) water-soluble foods, including fruit flavored drinks, sugar confectionery, sweets, etc.Keywords: Synthetic colors, Food, Fruit flavored drinks, Solid phase extraction, RP-HPL

Synchronous Reluctance Machine (SynRM) in Variable Speed Drives (VSD) Applications

This thesis is comprehensively dedicated to the theoretical and experimental reevaluation of the Synchronous Reluctance Machine (SynRM). A simple approach to derive the SynRM main characteristics and behavior is followed. An introduction to an evaluation of the different control strategies in is given. Finding suitable rotor geometry for the SynRM has been a subject for major investigation since 1923. This thesis will investigate the interior barrier rotor structure of the SynRM using the Finite Element Method (FEM) based sensitivity analysis. The Permanent Magnet assisted SynRM (PMaSynRM) is studied. The main aim here is to address accurately, qualitatively and quantitatively the main characteristics of such a machine. A heat-run test has been done on a prototyped SynRM and its corresponding IM and Interior Permanent Magnet (IPM) Machine to investigate the potential of the SynRM, under variable speed drive (VSD) supply conditions. This gives the state-ofart based on these measurements on the prototype SynRM and benchmarks its performance. The main behavior and characteristics of an anisotropic structure, suitable for high performance SynRM rotor geometry design, is distinguished and discussed. The carefully selected general rotor shape and some optimum distribution rules are used to develop a novel FEM-aided fast rotor design optimization for SynRM. Torque ripple minimization of SynRM is discussed. This is done by the development of a general method that minimizes the ripple independent of the stator structure. The torque ripple and interconnection to iron losses are briefly discussed. Based on these design tools, a design that is a compromise between the final machine?s performance and simplicity of the rotor structure is studied as the improved machine design. The fine tuned most promising design is prototyped and its performance compared with IM. Naturally, to have an anisotropic structure the q-axis flux must be blocked and simultaneously the d-axis flux must flow smoothly. One possibility is to align the barrier edges along the d-axis natural flux lines in the solid rotor. A prototype of the final optimized machine design SynRM is manufactured. The performance of this machine is measured and compared with the improved machine design. The effect of the number of poles on SynRM performance is discussed. Some of the most important secondary effects in SynRM are studied. Skew and torque quality, the possible effects of alternative voltage or current source supplies on torque and iron losses, the start-up and short-circuit locked rotor tests performed on the standard IM and the prototype SynRM and the effect of eccentricity are investigated. An overview comparison between IM and SynRM is given. For this purpose, a high performance rotor structure for SynRM with standard sizes of 3kW, 15kW and 90kW is designed. The thermal performance of the SynRM is discussed by analyzing the measured machine temperatures. A detailed picture regarding the thermal performance of the SynRM machine is presented. A full scale performance evaluation of the SynRM in comparison to its counterpart the IM is given. All IM and SynRM motors have the same standard stator for each size. The MTPA control strategy is used. Finally, all reported measurements in this thesis are summarized and analyzed.QC 20110518</p

Synchronous Reluctance Machine (SynRM) Design

The Synchronous Reluctance Motor (SynRM) has been studied. A suitable machine vector modelhas been derived. The influence of the major parameters on the motor performance has beentheoretically determined.Due to the complex rotor geometry in the SynRM, a suitable and simple combined theoretical(analytical) and finite element method has been developed to overcome the high number ofinvolved parameters by identifying some classified, meaningful, macroscopic parameters.Reducing the number of parameters effectively was one of the main goals. For this purpose,attempt has been made to find and classify different parameters and variables, based on availableliteratures and studies. Thus a literature study has been conducted to find all useful ideas andconcepts regarding the SynRM. The findings have been used to develop a simple, general, finiteelement aided and fast rotor design procedure. By this method rotor design can be suitablyachieved by related and simplified finite element sensitivity analysis.The procedure have been tested and confirmed. Then it is used to optimize a special rotor for aparticular induction machine (IM) stator. This optimization is mainly focused on the torquemaximization for a certain current. Torque ripple is also minimized to a practically acceptablevalue. The procedure can also be used to optimize the rotor geometry by considering the othermachine performance parameters as constrains.Finally full geometrical parameter sensitivity analysis is also done to investigate the influence ofthe main involved design parameters on the machine performance.Some main characteristics like magnetization inductances, power factor, efficiency, overloadcapacity, iron losses, torque and torque ripple are calculated for the final designs and in differentmachine load conditions.Effects of ribs, air gap length and number of barriers have been investigated by means of suitableFEM based method sensitivity analysis

Synchronous Reluctance Machine (SynRM) Design

The Synchronous Reluctance Motor (SynRM) has been studied. A suitable machine vector modelhas been derived. The influence of the major parameters on the motor performance has beentheoretically determined.Due to the complex rotor geometry in the SynRM, a suitable and simple combined theoretical(analytical) and finite element method has been developed to overcome the high number ofinvolved parameters by identifying some classified, meaningful, macroscopic parameters.Reducing the number of parameters effectively was one of the main goals. For this purpose,attempt has been made to find and classify different parameters and variables, based on availableliteratures and studies. Thus a literature study has been conducted to find all useful ideas andconcepts regarding the SynRM. The findings have been used to develop a simple, general, finiteelement aided and fast rotor design procedure. By this method rotor design can be suitablyachieved by related and simplified finite element sensitivity analysis.The procedure have been tested and confirmed. Then it is used to optimize a special rotor for aparticular induction machine (IM) stator. This optimization is mainly focused on the torquemaximization for a certain current. Torque ripple is also minimized to a practically acceptablevalue. The procedure can also be used to optimize the rotor geometry by considering the othermachine performance parameters as constrains.Finally full geometrical parameter sensitivity analysis is also done to investigate the influence ofthe main involved design parameters on the machine performance.Some main characteristics like magnetization inductances, power factor, efficiency, overloadcapacity, iron losses, torque and torque ripple are calculated for the final designs and in differentmachine load conditions.Effects of ribs, air gap length and number of barriers have been investigated by means of suitableFEM based method sensitivity analysis

3-D FEM Investigation of Eddy Current Losses in Rotor Lamination Steel Sheets

In this paper, a test setup that emulates field conditions equivalent to the ones of the rotor of a Salient Pole Synchronous Machine (SPSM) is presented. A 3-D Finite Element Method (FEM) model of the test setup is used to examine the induced eddy currents and to estimate losses using direct eddy current calculation method. The high mesh resolution of the model enables an accurate calculation and detailed illustration of the induced eddy currents as well as the estimation of related losses via direct computation within the volume of the test samples. A comparison of the estimated eddy current losses is made for different lamination thicknesses and materials of the test object. In the paper it is shown that the approximation that the eddy current losses are directly proportional to the square of the lamination thickness is not valid in the considered cases.Part of proceedings: ISBN 978-1-5386-2477-7QC 20181029</p

Different Traction Motor Topologies Used in E-mobility : Part I: Solutions without magnet

This paper presents a comparative study on different traction motor topologies that have the potential to be used in E-mobility applications. Some of the topologies, e.g. Interior Permanent Magnet (IPM) motors and Induction Motors (IM), are already driving vehicles on the road. In the paper first part, different induction motors and a Synchronous Reluctance Motor (SynRM) are discussed. Magnet-based traction motors are presented in the paper second part. The pros and cons of each design from performance to production and reliability points of view are explained and compared. Additionally, the operating principle together with the rotor structure of the IM and SynRM are detailed. On the induction motor, influence of using both the aluminium and copper in the rotor structure with two different frame sizes is studied. The performance parameters such as efficiency, power factor, torque density, field weakening, as well as the reliability and maturity are discussed. Experimental setup and measurement results on both these motor topologies are presented verifying accuracy of the simulation models used in this study