As a kind of traction device, interior permanent-magnet synchronous machines (IPMSMs) are widely used in modern electric vehicles. This paper performs a design and comparative study of IPMSMs with different rotor topologies (spoke-type PMs, tangential-type PMs, U-shape PMs, and V-shape PMs). The research results indicate that the IPMSM with V-shape PMs is more satisfying with comprehensive consideration. Furthermore, the IPMSM with V-shape PMs is investigated in detail. The influences of geometrical parameters (magnetic bridge and angle between the two V-shape PMs under each pole, etc.) on the performances of V-shape motor are evaluated based on finite-element method (FEM). For accurate research, the effects of saturation, cross-magnetization, and the change in PM flux linkage on d - and q -axis inductances are considered. The back-electromotive force (EMF), flux leakage coefficient, average torque, torque ripple, cogging torque, power per unit volume, power factor, and flux-weakening ability are investigated, respectively. The experimental results verify the validity and accuracy of the process presented in this paper.

Research on the Performances and Parameters of Interior PMSM Used for Electric Vehicles

Cogging torque in permanent-magnet machines causes torque and speed ripples, as well as acoustic noise and vibration, especially in low speed and direct drive applications. In this paper, a general analytical expression for cogging torque is derived by the energy method and the Fourier series analysis, based on the air gap permeance and the flux density distribution in an equivalent slotless machine. The optimal design parameters, such as slot number and pole number combination, skewing, pole-arc to pole-pitch ratio, and slot opening, are derived analytically to minimize the cogging torque. Finally, the finite-element analysis is adopted to verify the correctness of analytical methods.

Analytical Methods for Minimizing Cogging Torque in Permanent-Magnet Machines

Fermented foods and beverages possess various nutritional and therapeutic properties. Lactic acid bacteria (LAB) play a major role in determining the positive health effects of fermented milks and related products. The L. acidophilus and Bifidobacteria spp are known for their use in probiotic dairy foods. Cultured products sold with any claim of health benefits should meet the criteria of suggested minimum number of more than 10⁶ cfu/g at the time of consumption. Yoghurt is redefined as a probiotic carrier food. Several food powders like yoghurt powder and curd (dahi) powder are manufactured taking into consideration the number of organisms surviving in the product after drying. Such foods, beverages and powders are highly acceptable to consumers because of their flavor and aroma and high nutritive value. Antitumor activity is associated with the cell wall of starter bacteria and so the activity remains even after drying. Other health benefits of fermented milks include prevention of gastrointestinal infections, reduction of serum cholesterol levels and antimutagenic activity. The fermented products are recommended for consumption by lactose intolerant individuals and patients suffering from atherosclerosis. The formulation of fermented dietetic preparations and special products is an expanding research area. The health benefits, the technology of production of fermented milks and the kinetics of lactic acid fermentation in dairy products are reviewed here.

Fermented Milks and Milk Products as Functional Foods—A Review

Topology and Selection Definitions, Geometry, and Thrust Generation Linear Synchronous Motor Topologies Calculation of Forces Linear Motion Selection of Linear Motors Materials and Construction Materials Laminated Ferromagnetic Cores Permanent Magnets Conductors Principles of Superconductivity Laminated Stacks Armature Windings of Slotted Cores Slotless Armature Systems Electromagnetic Excitation Systems Superconducting Excitation Systems Hybrid Linear Stepping Motors Theory of Linear Synchronous Motors Permanent Magnet Synchronous Motors Motors with Superconducting Excitation Coils Variable Reluctance Motors Permanent Magnet Hybrid Motors Motion Control Control of AC Motors EMF and Thrust of PM Synchronous and Brushless Motors Dynamic Model of a PM Motor Thrust and Speed Control of PM Motors Control of Hybrid Stepping Motors Precision Linear Positioning Sensors Linear Optical Sensors Linear magnetic Encoders High Speed Maglev Transport Electromagnetic and Electrodynamic Levitation Transrapid System (Germany) Yamanashi Maglev Test Line in Japan Swissmetro Marine Express Building and Factory Transportation Systems Elevator Hoisting Machines Ropeless Elevators Assessment of Hoist Performance Horizontal Transportation systems Industrial Automation Systems Automation of Manufacturing Processes Casting Processes Machining Processes Welding and Thermal Cutting Surface Treatment and Finishing Material Handling Testing Industrial Laser Applications Appendix A Magnetic Circuits with Permanent Magnets Appendix B Permeances for Magnetic Fluxes Appendix C Performance Calculations for PM LSMs Symbols and Abbreviations References

Linear Synchronous Motors : Transportation and Automation Systems

This paper develops and analyzes a parametric model for simulating healthy and faulty surface-mounted permanent magnet synchronous motors. It allows studying the effects of stator winding interturn short-circuit faults. A relevant feature of the developed model is that it deals with spatial harmonics due to a nonsinusoidal rotor permanent magnet configuration. Additionally, the proposed model is valid for studying the behavior of these machines running under nonstationary conditions, including load or speed variations. Stator current spectra obtained from simulations performed by applying the proposed model show a close similitude with experimental results, highlighting the potential of such a model to understand the effects of stator winding failures on the current spectrum and allowing it to carry out an automatic diagnosis of such faults.

Modeling of Surface-Mounted Permanent Magnet Synchronous Motors With Stator Winding Interturn Faults

This paper reviews and summarizes Maglev train technologies from an electrical engineering point of view and assimilates the results of works over the past three decades carried out all over the world. Many researches and developments concerning the Maglev train have been accomplished; however, they are not always easy to understand. The purpose of this paper is to make the Maglev train technologies clear at a glance. Included are general understandings, technologies, and worldwide practical projects. Further research needs are also addressed.

Review of maglev train technologies

This paper presents a study on shape design of permanent magnets that is focused on robustness for cogging torque, sinusoidal back emf, and partial demagnetization of the permanent magnet of the outer rotor permanent magnet synchronous motor (PMSM). The simulation method for partial demagnetization is proposed and performed with four kinds of permanent magnet shape models at the fault current and two kinds of load angles corresponding to maximum torque operation and short circuit operation by finite-element method (FEM). The robust shape model of permanent magnets for large-sized hybrid electric vehicles is presented. The characteristics after partial demagnetization are analyzed and compared with experimental results for verification of the partial demagnetization effect

The Shape Design of Permanent Magnet for Permanent Magnet Synchronous Motor Considering Partial Demagnetization

This paper presents the optimal design method of synchronous reluctance motor (SynRM) for the high torque and power factor. It is difficult to design optimal barrier shape of rotor by analytical method because of leakage flux between barriers and saturation in the core. Therefore, the optimal design of SynRM including rotor structure is proposed in this paper by using finite element method (FEM) and simulation design of experiment (DOE). Finally, the characteristics of optimal model are compared with those of the worst one

A Study on the Optimal Design of SynRM for the High Torque and Power Factor

In this paper, the design methodology of a rotor for the interior permanent magnet motor (IPMSM) considering pole-arc to pole-pitch ratio and saliency parameter owing to PM and duct structure is proposed in order to improve the characteristics such as average torque, torque ripple, cogging torque and back EMF waveform. Especially, demagnetization effect due to duct design is analyzed by using the finite element method (FEM)

A Study on the Characteristics Due to Pole-Arc to Pole-Pitch Ratio and Saliency to Improve Torque Performance of IPMSM

OBJECTIVE: To examine whether the high incidence of herpes zoster in patients with systemic lupus erythematosus (SLE) is associated with the frequency of memory T cells specific to varicella zoster virus (VZV). METHODS: Whole blood samples from 47 subjects [24 patients with SLE, 11 with rheumatoid arthritis (RA) as a disease control, and 12 healthy negative controls] were stimulated with VZV antigen, stained for surface CD4 and CD8 and intracellularly stained for the cytokines interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukin 4 (IL-4), and IL-10, followed by flow cytometry analyses. Correlations of VZV-specific T cell frequencies with the clinical status of patients were analyzed. RESULTS: Percentage of IFN-gamma-positive CD4 T cells was significantly lower in patients with SLE (0.043 +/- 0.009%) than in RA (0.102 +/- 0.019%) and healthy controls (0.126 +/- 0.025%) upon VZV stimulation. A similar pattern was seen in TNF-alpha-positive CD4 T cell responses. These low frequencies of VZV-specific CD4 T cells in patients with SLE were significantly related with disease activity (r = -0.435, p = 0.043). CONCLUSION: These data suggest that the high incidence of herpes zoster in patients with SLE was related to the intrinsic defects in controlling VZV reactivation, and thus VZV-specific CD4 T cell frequency could be another practical risk factor of herpes zoster in patients with SLE.

https://www.jrheum.org/content/jrheum/31/11/2151.full.pdf

Association of reduced CD4 T cell responses specific to varicella zoster virus with high incidence of herpes zoster in patients with systemic lupus erythematosus.

Ki-Chan Kim

Papers

Review of maglev train technologies

The Shape Design of Permanent Magnet for Permanent Magnet Synchronous Motor Considering Partial Demagnetization

A Study on the Optimal Design of SynRM for the High Torque and Power Factor

A Study on the Characteristics Due to Pole-Arc to Pole-Pitch Ratio and Saliency to Improve Torque Performance of IPMSM

Association of reduced CD4 T cell responses specific to varicella zoster virus with high incidence of herpes zoster in patients with systemic lupus erythematosus.