The influence of periodic load on pulsations of electromagnetic torque and rotational speed, the losses and the efficiency of frequency-controlled induction motors for single-cylinder piston compressors are investigated using computer modeling. The region of critical reduction of motor efficiency when changing the frequency and supply voltage and the loading degree are determined using the criterion of heavy quasi-static regimes. References 16, figures 7, tables 2.

Обґрунтовано підходи до проектування асинхронних двигунів із змінним навантаженням з використанням критерію інтенсивних квазісталих режимів. Підходи апробовано на прикладі дослідження робочих режимів трифазних шестиполюсних асинхронних двигунів потужністю 700 Вт і 11 кВт приводу поршневих компресорів. Визначено можливості покращення ККД асинхронних двигунів у квазісталих режимах при зміні моменту інерції приводу та вибору оптимальних параметрів асинхронних двигунів за критерієм ефективності, що забезпечує максимальне значення ККД у робочих режимах. Ключові слова: проектування, асинхронний двигун, змінне навантаження, критерій інтенсивних квазісталих режимів, коефіцієнт корисної дії. Обоснованы подходы проектирования асинхронных двигателей с переменной нагрузкой с использованием критерия интенсивных квазиустановившихся режимов. Подходы были апробированы на примере исследования рабочих режимов трехфазных шестиполюсных асинхронных двигателей мощностью 700 Вт и 11 кВт привода поршневых компрессоров. Определены возможности повышения КПД асинхронных двигателей в квазиустановившихся режимах путем изменения момента инерции привода и выбора оптимальных параметров асинхронных двигателей с помощью критерия эффективности, что обеспечивает максимальное значение КПД в рабочих режимах. Ключевые слова: проектирование, асинхронный двигатель, переменная нагрузка, критерий интенсивных квазиустановившихся режимов, коэффициент полезного действия The design approaches of variable load induction motors using the criterion of intense quasi-steady-state modes are substantiated. With the help of the proposed criterion, the analysis of serial two-, four-and six-pole induction motors in the power range of 0.09-11 kW was performed. This made it possible to defined induction motors and their parameters (the number of pairs of poles, critical slip, moment of inertia) for which a refined designing is necessary into account the nature of the load. Approaches were tested on the example of the study of the operating modes of three-phase six-pole induction motors with a power of 700 W and 11 kW for single-and two-cylinder piston compressors. The possibilities of increasing the efficiency of induction motors in quasi-steady-state modes by changing the drive inertia moment and selecting the optimal induction motors parameters using the efficiency criterion, which provides the maximum efficiency value for quasistatics, were determined. The feasibility of applying approaches of design is proved by the example of calculating quasi-steady regimes of the six-pole induction motors with a power of 700 W for a two-cylinder compressor. A moment of inertia of the drive was determined, which allows to increase the efficiency in the quasi-steady regimes to its nominal value. It is shown that the optimal design of the induction motors with the constant basic moment of inertia of the drive and the variation in the length of the package and the number of effective stator winding conductors can increase the efficiency in operating modes by 10 %.

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Purpose. The purpose of the article is to create dependencies of efficiency on effective power when changing the supply voltage and switching angles, pulsation speeds of the rotor from the moment of inertia of the drive and mechanical characteristics of switched-reluctance motors with a periodic load, developing recommendations to ensure their effective and reliable operating modes in single-cylinder piston compressors. Methodology. To carry out research simulation mathematic modeling was used, to calculate the nonlinear inductance dependence on current and rotor angle, the finite element method. Results. The measures of improve the efficiency and reliability of drives single-cylinder piston compressors on the basis of the SRM has been proposed. Originality. Approaches that provide maximum efficiency values and a regulated level of ripple speeds of rotors SRM of single-cylinder reciprocating compressors in the operating frequency control range, with periodic load have been developed. Practical value. Algorithm for changing the supply voltage and switching angles of the SRM of single-cylinder compressors, which provides maximum efficiency values SRM when the rotational speed changes within the 1:6 range, has been developed. The minimum values of the moments of inertia of the drive of single-cylinder compressors, providing a regulated level of pulsations of the rotational speed of the rotor SRM with its regulation, were determined. References 10, figures 5.

The mode of operation of induction motors (IMs) affects their performance. In most cases, motors are optimally designed for steady state operation. When operating in other modes, additional attention is required to the problems of energy efficiency. Induction motors are the most common type of electromechanical energy converters, and a significant part of them operate under conditions of periodic changes in the load torque. The work is devoted to solving the problem of increasing the energy efficiency of asynchronous motors of electromechanical systems with a periodic load, including pumping and compressor equipment. The traditional solution to this problem for compressor equipment is the optimal design of an IM under static conditions, as well as the use of flywheels, the use of an IM with an increased slip value and controlled IM with a squirrel-cage rotor and with frequency converters. In this work, the modes of operation of asynchronous motors with periodic loading are investigated. For this, complex mathematical models are developed in the simulation system. Such models are effective in modeling taking into account periodic load changes: repetitive transient processes, their possible asymmetry and non-sinusoidality, increased influence of nonlinearity of electromagnetic parameters. In complex mathematical modeling, the mutual influence of the constituent parts of the electromechanical system is taken into account. Simulation allowed quantifying the deterioration in energy efficiency under intermittent loading, in comparison with static modes. Criteria for evaluating quasi-static modes have been developed and areas of critical decrease in efficiency have been determined. The paper proposes and demonstrates a methodology for solving this problem. For this purpose, tools have been created for the optimal design of asynchronous motors as part of electromechanical systems with periodic loading. These tools include: complex mathematical models of electromechanical systems with asynchronous motors with periodic load, mathematical tools for determining the parameters of quasi-steady-state modes, the methodology of optimal design based on the criterion of the maximum efficiency of processes under quasi-steady-state modes of operation. The possibilities, advantages and prospects of using the developed mathemati-cal apparatus for solving a number of problems to improve the efficiency of electric drives of compressor and pumping equipment are demonstrated. It is shown that by taking into account quasi-static processes, the use of complex mathematical models for the optimal design of asynchronous motors with a periodic load provides an in-crease in efficiency up to 8 ... 10%, relative to the indicators of motors that are de-signed without taking into account the quasi-static modes. The areas of intense quasi-steady-state modes are determined using the devel-oped criterion. In these areas, there is a critical decrease in efficiency compared to continuous load operation. A decrease in efficiency is associated with a decrease in the amount of kinetic energy of the rotating parts compared to the amount of electromagnetic energy. In connection with the development of a frequency-controlled asynchronous drive of mechanisms with a periodic load, the relevance of design taking into account the peculiarities of quasi-static has increased significantly. For example, a variable frequency drive of a refrigerator compressor or a heat pump can increase energy efficiency up to 40%, but at low speeds, due to a decrease in kinetic energy, the efficiency can decrease to 10 ... 15%, unless a special design methodology is applied. This problem can be solved by using the complex mathematical modeling tools developed in the article.