Optimum design of high-speed single-phase flux reversal motor with reduced torque ripple

Single-phase motors are used in low-power, cost-effective, variable-speed applications. As a replacement to traditional single-phase synchronous motors with magnets on the rotor, single-phase flux reversal motors (FRMs) with a rugged and reliable toothed rotor are considered for the high-speed applications. However, torque pulsations of single-phase motors are high. The aim of this work is to minimize the torque ripple and increase its minimum instantaneous value, as well as to reduce FRM losses. To solve this problem, an asymmetric rotor is used, and an objective function is proposed, which includes parameters characterizing the pulsations of the torque and the loss of FRM for two load conditions. To optimize the single-phase FRM and minimize the objective function, the Nelder-Mead method was applied. The optimization criterion was selected to maximize the efficiency, to reduce the torque ripple, and to the avoid the negative torque in a wide range of powers at the fan load (quadric dependence of torque on speed). Two operating loading modes are considered. After two stages of optimization, the peak-to-peak torque ripple in the FRM in the rated loading mode decreased by 1.7 times, and in the mode with reduced load by 2.7 times. In addition, in the FRM before optimization, the torque has sections with negative values, and in the FRM after optimization, the torque is positive over the entire period. Although losses in the rated mode increased by 4%, when underloaded, they decreased by 11%, which creates an additional advantage for applications that work most of the time with underload. © 2020 by the authors.Ministry of Science and Higher Education of the Russian Federation: FEUZ-2020-0060The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, Project No. FEUZ-2020-0060). The authors thank the editors and reviewers for careful reading, and constructive comments

Life cycle energy cost assessment for pump units with various types of line-start operating motors including cable losses

The paper presents a comparative analysis of life-cycle energy consumption for three different types of 4 kW line-start motors used in a pump unit with throttling: the most widely used induction motor with IE3 efficiency class, line start permanent magnet synchronous motor with IE4 efficiency class and line start synchronous reluctance motor with IE4 efficiency class. The operating cycle for pump units with constant flow is considered for the above-mentioned types of motors taking into account not only the losses in the pump and motor, but also in the power supply cable. It is shown that the line start synchronous reluctance motor without magnets has the highest efficiency over the entire considered loading range. However, its power factor is lower than that of the synchronous motor with magnets and therefore it has more significant losses in power supply cable. Despite this disadvantage, the line-start reluctance motor is a good alternative to widespread induction motor since it allows saving of approximately 4000 euro more than the latter during the 20 years life cycle. It also provides similar savings in comparison to the permanent magnet synchronous motor, but unlike it, it does not have costly rare-earth materials in the rotor. © 2020 by the authors

Feasibility study of pump units with various direct-on-line electric motors considering cable and transformer losses

The high energy intensity of the modern industry determines the high urgency of increasing the energy efficiency of production processes. However, a big number of motor types of enhanced efficiency classes are available on the market. The motor users can be confused about the choice of the right motor solution for a certain application. In this paper, to help with this choice the energy efficiency indicators of various types of electric motors in a low-power pump unit with a constant rotation speed are studied. Moreover, not only power losses in the motor are considered, but also power losses in the cable and transformer, which are influenced by the power factor of the motor. Induction motors (IMs) and synchronous motors powered directly from the grid (direct-on-line synchronous motor with permanent magnet in the rotor, DOL PMSM; direct-on-line synchronous reluctance motor without permanent magnet, DOL SynRM) of IE2, IE3, and IE4 energy efficiency classes are compared. To carry out the analysis, polynomial interpolation of the available catalogue data and experimental data of the motors are used. The main criteria for comparing different motors in this work are the energy savings over the pump’s life cycle and the payback period when replacing an IE2 motor with a motor of a higher energy efficiency class. The article shows that although the DOL PMSM has a lower motor efficiency than the DOL SynRM, it saves more energy due to its higher power factor, which reduces cable and transformer losses. It is also shown that, despite the highest initial cost, when taking into account cable and transformer losses, the payback period of DOL PMSM can be shorter than that of IE3 and IE4 induction motors. DOL SynRM has the shortest payback period in all considered cases, has no troublesome rare-earth permanent magnets, and can also be a valuable solution. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, Project No. FEUZ 2020-0060)

Design and Mathematical Modeling of Gearless SMC Flux Reversal Motor

This paper considers the design of a three-phase gearless flux reversal machine (FRM) with permanent magnets (PM) mounted on the stator. Its stator magnetic core is made of a solid soft magnetic composite material (SMC) with a slot for laying the winding in the middle. 48 magnetic poles are located on the surface of each stator tooth, while the rotor has 24 teeth. This paper describes the mathematical model and the results of the performance calculation of the three-phase SMC FRM operating in motoring mode. Finally, comparison of the SMC FRM with the characteristics of the conventional surface mounted permanent magnet machine (SM-PMSM) made of laminated steel is performed. For fair comparison, both the SMC FRM and SM-PMSM have the same outer stator diameter and approximately the same volume. © 2018 IEEE

The history of the forming and the features of the soil, lithological and geomorphological structure of the Jizzakh steppe as the basais for its natural zoning

The paper provides initial materials characterizing the complicated history of formation, natural soils and lithological-geomorphological conditions of the Jizzakh steppe before the beginning of reclamation development. It is shown that on the basis of soil-lithological and geomorphological zoning, the Jizzakh steppe is divided into a number of natural regions belonging to different levels (altitude levels) of the piedmont plain. In total, 22 districts have been identified within the Jizzakh steppe, including the foothill margins. On the piedmont plain itself, the regions are combined into two high-altitude levels: the upper step and the lower step or blanket zone. These two levels differ sharply in terms of drainage conditions and soil salinity. The upper level, covering the upper and middle parts of the alluvial fan, the high interconal Zaamin-Sanzar plain and the Lomakino plateau, is characterized by a weak manifestation of salinity due to relatively good drainage, except for the sloping depressions of the Lomakino plateau. In contrast to the upper level, the lower level, located in the blanket zone of the piedmont plain, is characterized by active natural salinization because of the poor drainage. The saline sediments of the Zaamin cone delta are characterized by the greatest thickness. To a lesser extent, the rocks of the Sanzar cone delta, which are drained by deep gullies, are salinized. The Khavast sloping plain is characterized by a strongly saline upper two-meter layer, with salt and gypsum content decreasing with depth. Thus, it is shown that high salinity and gypsum bearing rocks, as well as high groundwater salinity of the cone delta zone are the source of modern salt accumulation in soils of foothill Golodnostepskaya plain, as well as in soils of the cone delta zone of Djizak steppe

Tensor analyzing power Ayy in deuteron inclusive breakup at large Pt and spin structure of deuteron at short internucleonic distances

The Ayy data for deuteron inclusive breakup off hydrogen and carbon at a deuteron momentum of 9.0 GeV/c and large Pt of emitted protons are presented. The large values of Ayy independent of the target mass reflect the sensitivity of the data to the deuteron spin structure. The data obtained at fixed $x$ and plotted versus Pt clearly demonstrate the dependence of the deuteron spin structure at short internucleonic distances on two variables. The data are compared with the calculations using Paris, CD-Bonn and Karmanov's deuteron wave functions.Comment: 4 pages, 2 figures, talk given at the SPIN2004 Conf., 10-16 Oct. 2004, Triest, Ital

Legislative approaches to the electronic document definition and its evidentiary value in the CIS countries

This article considers the issues related to the electronic document definition according to the legislation of the member states of the Commonwealth of Independent States. Attention is focused on differences in the approaches to the structure of the electronic document, the electronic digital signature, the copy of electronic document, the use of electronic documents and electronic materials as evidence in the civil proces

Heat capacity of bulk boron doped single crystal HPHT diamonds in the temperature range from 2 to 400 K

Heat capacity Ср of boron-doped single crystal diamonds grown by the temperature gradient method was studied. Boron content was about < 10¹⁶, ~ 10¹⁸ and ~ 10²⁰ cm⁻³. Heat capacity data for all tested crystals match well within the measurement accuracy (1 %) in the temperature range of 150–400 K and obey the Debye law. At low temperatures heat capacity follows linear law possibly due to metallic inclusions in diamond bulk. Using this data the amount of metal can be calculated for each sample.Досліджено теплоємність Ср легованих бором монокристалічних алмазів, вирощених методом температурного градієнта. Вміст бору був < 10¹⁶, ~ 10¹⁸ і ~ 10²⁰ см⁻³. Дані по теплоємності для всіх досліджених кристалів добре узгоджуються в межах точності вимірювань (1 %) в інтервалі температур 150–400 К і підпорядковуються закону Дебая. При низьких температурах теплоємність змінюється за лінійним законом, можливо, через наявність металевих включень в алмазі. Використовуючи ці дані, кількість металу може бути обчислена для кожного зразка.Исследована теплоемкость Ср легированных бором монокристаллических алмазов, выращенных методом температурного градиента. Содержание бора было < 10¹⁶, ~ 10¹⁸ и ~ 10²⁰ см⁻³. Данные по теплоемкости для всех исследованных кристаллов хорошо согласуются в пределах точности измерений (1 %) в интервале температур 150–400 К и подчиняются закону Дебая. При низких температурах теплоемкость изменяется по линейному закону, возможно, из-за присутствия металлических включений в алмазе. Полученные данные позволяют рассчитать долю металлических включений в каждом из образцов

Coherent summation of emission from relativistic Cherenkov sources as a way of production of extremely high-intensity microwave pulses

For relativistic Cherenkov devices, we investigate the process of high-power microwave pulse generation with its phase correlating to the sharp edge of an e-beam current pulse. Our theoretical consideration is referred to quasi-stationary and superradiative (SR) generation regimes when spontaneous emission of the e-beam edge serves as the seed for the development of further coherent oscillations. Phase correlation of the excited microwave pulses with the characteristics of the current pulse front and/or an initial external electromagnetic pulse has been additionally confirmed by particle-in-cell simulations. Pulse-to-pulse stability of the radiation phase within several percents of the oscillation period makes it possible to arrange multichannel schemes producing mutually coherent microwave pulses. In the experiments that have been carried out, the cathodes of independent generators were powered by identical accelerating pulses from strictly synchronized voltage modulators, or by splitting the pulse from a single powerful modulator. For the 2-ns regime with the power of each Ka-band backward-wave oscillator about 100 MW, we demonstrate quadratic growth of the power density in the interference maximum of the directional diagram. In a short pulse SR regime, with the peak power of 600 MW in a single channel, for a four-channel 2-D array, we attained a 16-fold radiation intensity gain