Efficiency analysis of low electric power drives employing induction and synchronous reluctance motors in pump applications

Due to the rapid increase in the number of variable speed AC drives, the analysis of their energy efficiency has become highly essential. However, such an analysis requires consideration of a wide variety of factors. This includes considering the energy loss in the frequency converter, depending on the motor type. In this article, a computational comparison of the energy properties of variable frequency pump drive employing two types of electric machines, i.e. an induction and a synchronous reluctance motor, is presented. The effect of the motor type on the losses in a low-voltage two-stage frequency converter using analytical and numerical models, with a further comparison, is investigated. Furthermore, an alternative approach to determine the current magnitude and power factor of the load of the converter is suggested. Eventually, this study provides a quantitative estimate of the increase in losses in the converter caused by using the two different motor types. Several experimental tests are conducted on induction and synchronous 1.1 kW reluctance motors. © 2019 by the authors. Licensee MDPI, Basel, Switzerland

ОПТИМАЛЬНОЕ ПРОЕКТИРОВАНИЕ БЕЗРЕДУКТОРНОЙ МАШИНЫ С ПЕРЕКЛЮЧЕНИЕМ ПОТОКА ДЛЯ ВЕТРОГЕНЕРАТОРА

The relevance of the research is caused by the increasing need for autonomous hybrid power plants using renewable sources to reduce the consumption of fossil fuels. Improving the performance and reducing the cost of gearless wind generators used in such power plants will contribute to improvement of technical and economic characteristics of the plants. The main aim of the research includes the elaboration of an effective approach for optimizing the flux switching generator for gearless wind turbines, which reduces the use of computing resources, in comparison with existing approaches; elaboration of recommendations for the design of the flux switching wind generator with permanent magnets on the stator; improving the initial design of the generator. Objects of the research are the mathematical model and the design of flux switching generator with permanent magnets on the stator. Methods: assessment and analysis of wind speed data worldwide; derivative-free optimization method; finite element method; mathematical modeling; statistical methods. Results. The multicriteria optimization of the design of a gearless wind flux switching generator was carried out. As a result, the generator efficiency was increased, its torque ripple and the rated power of the electronic converter of the wind turbine system were reduced. General recommendations regarding the geometry are obtained which can be used for designing similar flux switching generators. A method is proposed for construction of substituting profiles of the operating characteristics of wind turbines, which can be used to reduce computational effort during the optimization. The computational cost reduction using the obtained method is demonstrated using the example of replacing the original nine-point working profile of a wind turbine with a substituting two-point one. © 2020 Tomsk Polytechnic University, Publishing House. All rights reserved

Regional features of the epidemiology of pterygium in the Republic of Bashkortostan

Background. Pterygium is ubiquitous and multifactorial; today, information on  the  prevalence of pterygium, risk factors, the relationship of its development with concomitant pathology and the type of life activity of patients in various regions of Russia is limited. All of the above led to the conduct of this epidemiological study in the Republic of Bashkortostan.The aim of the study: to study the prevalence of pterygium, as well as to identify the relationship of risk factors for its development with the type of life activity and concomitant diseases in the urban and rural population of the Republic of Bashkortostan.Methods. On the basis of the Ufa Research Institute of Eye Diseases, within the framework of the Ural Eye and Medical Study (UEMS) research project, a population study of people living in urban and rural regions of the Republic of Bashkortostan was carried out. The study involved 5899  people, including men – 43.7  % (2585  people), women – 56.3 % (3314 people), urban residents made 42.3 % (2491 people), rural – 57.7 % (3408 people).Results. As a result of our study, pterygium was diagnosed in 138 people (204 eyes – 2.3 %) (95% CI: 2.0–2.7 %). One-way analysis showed a higher prevalence of pterygium associated (p˂0.10) with a number of systemic and ophthalmic parameters. However, according to the results of multivariate analysis, it was revealed that the prevalence of pterygium was significantly associated with older age (p = 0.006), rural area of residence (p = 0.001) and low educational level (p = 0.03).Conclusion. The prevalence of pterygium in Republic of Bashkortostan according to the UEMS study was 2.3 %, or 23 people per 1000 population among people over 40 years old. The nature of the settlement influences the prevalence of pterygium in  the Republic of Bashkortostan. Pterygium was more common among older people among all respondents who took part in the study. In the study, pterygium was not a biomarker of general somatic diseases

Применение метода Нелдера–Мида для оптимизации одноименнополюсного синхронного двигателя для карьерного самосвала

The relevance of the study is in the increasing need for the use of mining dump trucks with a diesel-electric (hybrid) drive for the development of minerals. Improving the operational and cost characteristics of the electric drive of mining dump trucks helps to reduce costs in the development of minerals. The main aim of the study is to find an effective approach to optimizing a synchronous homopolar motor for driving the rear wheels of a mining dump truck, which makes it possible to solve the problem of the high demand for computing resources when simulating a three-dimensional magnetic field of the motor; develop the recommendations for the design of a synchronous homopolar motor with an excitation winding on the stator; apply the optimization to reduce power losses and maximum motor current for a given traction characteristic of the drive, and to reduce the current rating and cost of the semiconductor inverter module of the electric drive of a mining dump truck with the type of motor under consideration. Object of the research is a design of a six-pole nine-phase synchronous homopolar motor with an excitation winding on the stator with a power rating of 370 kW. Methods: derivative-free optimization method; equivalent circuit method; mathematical modeling; two-dimensional finite element method. Results. A novel approach to optimization of a synchronous homopolar motor is proposed. This approach is effective from the point of view of the accuracy of calculating the characteristics and computational costs. As a result of optimization, the motor losses and the maximum current required by the motor from the inverter have been significantly reduced. The achieved reduction of the motor current allows reducing the cost of the semiconductor modules of the inverter by 1,4 times (by 2295 United States dollars), and also allows reducing the alternating component in the current of the direct current link of the inverter by the same amount. © 2022 Tomsk Polytechnic University, Publishing House. All rights reserved.The research was performed with the support of the Russian Science Foundation grant (Project No. 21-19-00696)

СРАВНИТЕЛЬНЫЙ АНАЛИЗ ДВУХ ОДНОФАЗНЫХ ВЫСОКОСКОРОСТНЫХ МАШИН С МАГНИТАМИ НА СТАТОРЕ

Purpose. Single-phase machines with permanent magnets on the rotor are widely used in a variety of applications of a low rated power. When these machines are applied in high-speed applications, a retaining ring on the rotor core must be often used. However, it makes the assembly more complex and the high-speed machines become more expensive. On the other hand, machines with magnets on the stator still can be a valuable alternative due to their simple and reliable rotor design. In this paper the comparative study of performances of two single-phase electrical machines with magnets on the stator (flux reversal electrical machine and hybrid switched reluctance machine) is presented. The following performances have been compared: efficiency, weight, active materials cost, value of rated current of switches of the frequency converter. Methodology. Calculation of electrical machines performances using solving two-dimension boundary magnetostatics problems. Results. The theoretical comparison of the flux reversal electrical machine and the hybrid switched reluctance machine has been carried out; the comparison on specific torque and efficiency of the two aforementioned machines have been obtained. The flux reversal machine has a significantly higher efficiency and  a fewer weight. In addition, it has a lower value of rated current. On the contrary, the cost of active materials of the hybrid switched reluctance one is much less. Originality. The presented results can assist in selecting the best design alternative of electrical machines in the following applications: electrical blowers, household appliances, fans, pumps and compressors of a low rated power etc. Practical value. The comparisons results of the flux reversal electrical machine and the hybrid switched reluctance machine has been obtained for the first time.Цель. Исследование характеристик двух высокоскоростных однофазных электрических машин с магнитами на статоре (электрическая машина с переменным направлением потока и гибридная вентильно-индукторная реактивная машина): сравниваются такие характеристики как КПД, вес, стоимость активных материалов, номинальный ток элементов преобразователя частоты. Методика. Расчет характеристик электрической машины с помощью решения двухмерных краевых магнитостатических задач. Результаты. Произведено сопоставление двух типов однофазных машин с магнитами на статоре; получено расчетное сравнение характеристик однофазной электрической машины с переменным направлением потока и однофазной гибридной вентильно-индукторной реактивной машины; получены результаты сравнения массы и размеров КПД двух машин. Научная новизна. Впервые получены результаты сравнения однофазной электрической машины с переменным направлением потока и однофазной гибридной вентильно-индукторной реактивной машины. Практическое значение. Полученные результаты могут помочь при выборе лучшей конструкцией электродвигателя в рассматриваемых приложениях: электрический турбонаддув, бытовые приборы, вентиляторы, насосы и компрессоры малой мощности и т.д

СРАВНЕНИЕ ЭНЕРГОПОТРЕБЛЕНИЯ РАЗЛИЧНЫМИ ЭЛЕКТРОДВИГАТЕЛЯМИ, РАБОТАЮЩИМИ В СОСТАВЕ НАСОСНОГО АГРЕГАТА

Purpose. Comparative analysis of energy consumption of various types electric motors in fixed speed centrifugal industrial pump applications is carried out. The purpose of the analysis is to choose the most efficient motor in the considered application. It is assumed that hydraulic flow of the pump is adjusted by throttling. The rated power of the pump unit is 2.2 kW. Direct on line motors of various energy efficiency classes from various manufacturers are considered: induction motors with permanent magnets on the rotor of IE4 class and squirrel cage induction motors of IE3 and IE4 classes. Methodology. Assessment of energy consumption of the motors is carried out based on the catalogue data from manufacturers of the pump and the motors. Pump hydraulic equations, interpolation of motor catalogue data and statistical data are also used. Results. The following values have been obtained: annual and daily energy consumption of the motors and electricity cost savings comparing with the least effective motor considered. Practical value. The following practical consideration are presented based on the theoretical results: choosing the motor based only on its IE efficiency class according to IEC 60034-30-1 is not enough to ensure the minimum energy consumption of pump units with variable flow during the load cycle. In addition, the energy consumption may be higher in the case of permanent magnet motors of IE4 class in comparison with induction motors of IE4 or even IE3 class. Therefore, it is necessary to take into account efficiency of the motors at underload and it is needed to calculate the energy consumption during the actual load cycle. It should be noted, that the existing approach based on the Energy Efficiency Index (EEI) calculation does not provide information about absolute values of energy savings and cost savings, in contrast to the described approach. While choosing motors to run in the considered application it is also important to take into account that the motors with permanent magnets on the rotor have significantly higher price and very restricted starting capabilities comparing with induction motors. In addition, the production of rare earth magnets causes a significant environmental damage.Цель. Сравнительный анализ энергопотребления электродвигателей разных типов и классов энергоэффективности в электроприводе центробежного насоса мощностью 2,2 кВт системы водоснабжения с дроссельным регулированием. Сравнивались синхронные электродвигатели с прямым пуском и постоянными магнитами на роторе класса энергоэффективности IE4 и асинхронные электродвигатели классов энергоэффективности IE4 и IE3 различных производителей. Методика. Расчет энергопотребления проводился на основе данных насоса и электродвигателей, предоставляемых производителями, и включал в себя расчет энергопотребления центробежным насосом в типовом рабочем цикле, предполагающем работу с пониженными нагрузками в течение продолжительного времени. Результат. Получены расчетные данные по суточному и годовому энергопотреблению рассмотренных электродвигателей в типовом рабочем цикле насоса, годовая стоимость электроэнергии исходя из среднеевропейского тарифа, экономия в денежном выражении относительно наихудшего электродвигателя из рассмотренных. Практическое значение. Показано, что выбор электродвигателя по КПД при номинальной нагрузке, то есть фактически на основе присвоенного в соответствии со стандартом IEC 60034-30-1 класса энергоэффективности IE, не приводит к минимальному энергопотреблению центробежного насосного агрегата с переменной подачей в течение типового рабочего цикла. Также показано, что применение в насосных агрегатах с переменным расходом синхронных электродвигателей с прямым пуском и постоянными магнитами класса IE4 в ряде случаев приводит к большему энергопотреблению, чем применение асинхронных электродвигателей класса IE4, а иногда и класса IE3. Таким образом, при выборе класса энергоэффективности электродвигателя как для насосного агрегата, так и для любого другого механизма, работающего значительное время при пониженных нагрузках, следует проводить расчет энергопотребления на основании данных о типовом рабочем цикле либо экспериментальных данных. При этом существующий подход, основанный на определении индекса энергетической эффективности EEI, не дает информации об экономии электроэнергии в натуральном и стоимостном выражениях, в отличие от описанного в работе подхода. При выборе электродвигателя по принципу действия следует учитывать помимо энергопотребления, то, что синхронные электродвигатели с постоянными магнитами имеют большую стоимость, чем асинхронные электродвигатели, имеются трудности их запуска при значительном моменте инерции, а получение магнитов из редкоземельных металлов сопряжено со значительным экологическим ущербом

A comparative evaluation of the energy consumption parameters of a gasoline generator set with constant and variable rotational speed

The paper presents a comparative mathematical study of the energy parameters of two gasoline generator sets with constant and variable rotational speed. Issues include the advantages of using a generator set with variable speed.В работе приведен сравнительный расчетный анализ энергетических показателей бензо-генераторных установок с постоянной и переменной частотами вращения. Сделаны выводы относительно преимуществ применения установки с переменной частотой вращения

АНАЛИЗ ПОТРЕБЛЕНИЯ ЭЛЕКТРОЭНЕРГИИ АСИНХРОННЫМИ ДВИГАТЕЛЯМИ КЛАССОВ ЭФФЕКТИВНОСТИ IE1 И IE2 В НАСОСНОЙ УСТАНОВКЕ МОЩНОСТЬЮ 11 кВт

Purpose. Comparative analysis of energy consumption indicators of electric motors of different energy efficiency classes in an electric drive of a centrifugal pump with power of 11 kW of a water supply system with throttle regulation. Methodology. In this paper a comparison of energy consumption of 11 kW pump units with induction motors of energy efficiency classes IE1 and IE2 is presented. The induction motors are powered directly from the mains. Both considered pump configurations have the same fluid flow rate characteristic of open pump systems. The amount of water consumed by the pump is adjusted by throttling. Results. The results on the daily and annual energy consumption of the two considered pump system configurations are obtained. It is shown that the pump unit using the IE2 class motor provides the annual energy savings of 9.65 thousand rubles and the life cycle energy savings of 158 thousand rubles compared to the IE1 class motor. The payback period of the IE2 class motor is calculated, which is 5 months if a new installation is commissioned and 2 years if the motor is replaced in an operating installation. Practical value. Nowadays the countries of the Eurasian Economic Union mainly use electric motors of the lowest energy efficiency class IE1, according to the IEC 60034-30 Standard (GOST IEC 60034-30-1-2016). However, according to the decision of the Commission of the Eurasian Economic Union, since the 1st of September, 2021 all general-purpose motors shall not be less efficient than the IE2 efficiency level. Therefore, the analysis of the economic effect of replacing IE1 class motors with IE2 class motors becomes relevant for the countries of the Eurasian Union. Pump drives are one of the most important consumers of electricity. Most of the pump drives are powered directly from the mains.На сегодняшний день в странах Евразийского экономического союза в основном применяются электродвигатели низкого класса энергоэффективности IE1, согласно стандарту МЭК 60034-30 (ГОСТ МЭК 60034-30-1-2016). Однако, согласно решению комиссии Евразийского экономического союза, с 1 сентября 2021 г. значение коэффициента полезного действия двигателей не должно быть меньше значений, установленных для класса энергетической эффективности IE2. Поэтому для стран Евразийского союза актуальным становится анализ экономического эффекта от замены двигателей класса IE1 на двигатели класса IE2. В данной работе представлен сравнительный анализ показателей энергопотребления асинхронных электродвигателей классов энергоэффективности IE1 и IE2 в электроприводе центробежного насоса мощностью 11 кВт системы водоснабжения с дроссельным регулированием. Асинхронные двигатели питаются напрямую от электрической сети. Обе насосные системы имеют один и тот же график расхода жидкости, характерный для разомкнутых насосных систем. Количество расходуемой насосом воды регулируется за счет дросселирования. Получены результаты по суточному и годовому энергопотреблению двух рассмотренных конфигураций насосной системы. Показано что система, где применяется асинхронный двигатель класса энергоэффективности IE2, обеспечивает экономию 118,6 евро за год и 2000 евро за жизненный цикл, по сравнению с асинхронным двигателем класса IE1. Рассчитан срок окупаемости двигателя класса IE2, который составляет 5 месяцев в случае введения в строй новой установки и 2 года, в случае замены двигателя в работающей установке.

Analysis of the Payback Period of a Modernized Pump Unit with Induction Electric Motors of Advanced Energy Efficiency Classes

Aim. The comparative analysis of energy consumption, electricity costs during lifetime cycle and payback period of a pump unit with 90 kW 2-pole induction motors, belonging to various energy efficiency classes, feeding directly from power grid. Methods. The examined operating modes aligned with a typical operating cycle of a pump unit with approximately constant flow rate of 75-110 % of the rated flow. The calculations were based on the pump and induction motors nameplate data, which, in their turn, were based on the manufacturers’ experimental data. Results. The calculations of energy consumption, electricity costs and payback periods of a pump unit with 90 kW 2-pole induction motors, feeding directly from power grid have been performed in the article. The application of induction motors belonging to IE2, IE3 and IE4 energy efficiency classes has been discussed. Practical value. It has been demonstrated, than in case of replacement of an induction motor of energy efficiency class IE2 due to planned retrofit, payback period for an IE4 induction motor is 2.18 years, energy savings within a calculated 20-year operating period are 268MW·h, which makes €41110 in money terms. under the same conditions, the replacement of an induction motor of energy efficiency class IE2 with an induction motor of energy efficiency class IE3 will allow to save 88 MW·h within a calculated operating period, which, expressed in monetary terms, is €13500 and the payback period is 5.11 years. Thus, the article proves that despite a higher initial price, the choice of an induction motor of energy efficiency class IE4 tends to be more economically advantageous. © 2021, National Technical University "Kharkiv Polytechnic Institute". All rights reserved.Acknowledgment. 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)

EVALUATION OF UNCERTAINTY OF THE ELECTRIC MOTOR EFFICIENCY MEASUREMENT BY THE INPUT-OUTPUT METHOD

The method of evaluation of the combined measurement uncertainty of the motor efficiency, based on the uncertainties of electrical and mechanical power, is presented. Particular attention is paid to the evaluation of the shaft torque uncertainty as it is one of the most significant.В работе рассмотрен метод определения результирующей погрешности измерения КПД электродвигателя, на основе погрешностей электрической и механической мощностей. Особое внимание уделено определению погрешности момента на валу двигателя, так как она является одной из самых значительных