Theory Of Electrical Machines Research Articles

МАТЕМАТИЧНА МОДЕЛЬ МАГНІТОЕЛЕКТРИЧНОЇ МАШИНИ

A mathematical model is proposed for the calculation of electromagnetic parameters of magnetoelectric machines using an analytical method. Permanent magnets are abstracted as equivalent solenoids with constant current represented as current loops. The model differs from known models by the presence of double linear current loops in the stator for the analysis of magnetoelectric machines with a two-layer winding. Additionally, the proposed model considers linear current loops of equivalent solenoids instead of point current loops for a more accurate calculation. The current loops of the stator and rotor are defined at the boundaries of the air gap of the electric machine, i.e., on the smooth slotless surfaces of the magnetic cores. The current loops are expressed for the first time as a product of three variables: current strength, linear current density coefficient, and spatial distribution coefficient. The inductance of stator slots and the resistance of the winding are taken into account using known analytical expressions from classical electric machine theory. The rotor rotation frequency is presented as a function of time. For magnetoelectric machines of specified dimensions and a given variable rotor rotation frequency, the distribution of magnetic field induction, vector magnetic potential, currents, winding spatial distribution coefficients, and electric field intensity of permanent magnets are calculated using the mathematical model. References 7, table 1, figures 4.

Analytical model of dynamic system "long cable - submersible induction motor with fixed rotor" in polar coordinate system

Relevance. The stock of oil wells in the Russian Federation, where production is carried out with the help of electric centrifugal pumps or electric-driven vane pumps, is expanding every year. This trend will continue for at least a couple of decades. In its turn, the number of wells with readily available oil products in the commissioned stock is decreasing. This leads to the need to improve production quality and reduce energy consumption to maintain profitability and production volumes. This can be achieved by implementing vector energy-efficient control systems for submersible motors based on observers of induction motor state variables. In this case one should take into account transients in the supply cable of considerable length, which transmits energy from a frequency converter to a motor. The observers are based on adjustable mathematical models that describe electrical, electromechanical and mechanical processes in electric drive and related process automation systems as reliably as possible. Using complex and cumbersome adjustable mathematical models in digital signal processors due to limited performance and memory causes objective difficulties in obtaining solutions of increased accuracy in real time. On this basis, the development of an analytical model of the dynamic system "long cable – submersible induction motor with fixed rotor" in the polar coordinate system is an urgent task. Aim. Development of analytical description of the mathematical model of the induction motor with a fixed rotor in the polar coordinate system taking into account the influence of a long cable. Methods. Electric drive theory, electric machine theory, mathematical models of submersible induction motors and reduced long cable model, Vandermonde's determinant, analytical methods for solving differential equations. Result and conclusions. The authors have developed an analytical model of the regulated induction motor with a fixed rotor in the polar coordinate system taking into account the supply cable of considerable length. The developed analytical model is recommended for use in vector energy-efficient electric drive with application of phase discrimination principles taking into account the influence of processes in the supply cable line. Such electric drive has a potential for increasing the profitability of oil production from low- and medium-debt wells.

Разработка метода идентификации синхронного сопротивления турбогенератора и критериев выбора состава данных синхронизированных векторных измерений

To enhance power system dependability and efficiency, it is of great importance to obtain correct parameters of the models of key power system components such as a synchronous generator (SG). Technology of synchronized phasor measurements allows us to estimate the SG model parameters through measurements in power system steady states and transients states, without switching the SG off and conducting complex testing procedures. The theory of electric circuits and electric machines, theory of optimization and statistics, and matrix algebra are applied in this study. The developed parameter estimation method has been implemented in the MATLAB software. The method has been verified through real-world measurements captured by a phasor measurement unit installed at a large power plant in the United Power System. This paper presents an algorithm of the turbogenerator synchronous reactance estimation via a set of synchrophasor data taken under steady-state conditions. Also, the paper considers the criteria for an appropriate data array ensuring successful parameter estimation. An algorithm has been developed and implemented in MATLAB software package. To improve the parameter estimation accuracy, an algorithm has been proposed to modify a nominal value for the SG no-load excitation current depending on the heating of the field winding. The algorithm has been successfully tested out based on a set of steady state synchrophasor data captured for one of the turbogenerators in the Russian United Power System. The authors have developed and analyzed quantitative criteria to determine a set of measured parameters of steady-state modes, providing the most accurate results of the turbogenerator synchronous reactance. The developed algorithm allows accurate update of the turbogenerator synchronous parameters through synchrophasor measurements recorded in a steady state modes of electric power systems. Using the criteria for selecting phasor data, it seems possible to automate the process of generating a data array of measurement of various steady-state modes necessary for identification. The proposed procedure that considers the field winding temperature can be employed in math models to estimate SG transient and subtransient parameters based on phasor measurements in transient modes of electric power systems.

Simulation of autonomous voltage inverters of power sources of single-phase asynchronous drives

Purpose. Development of original models of voltage inverters adapted to control a single-phase asynchronous motor with the subsequent prospect of creating automatic systems for improving the energy efficiency of household mechanisms, as well as developing educational complexes for studying the operation of frequency converters to form skills for their repair and tuning.Methodology. The provisions of the theory of electric machines, methods of synthesis of digital control systems, methods and methods of modeling in CAD electronic laboratory of the company NATIONAL INSTRUMENTS of the Multisim component, methods of circuit design were used for conducting research. Findings. Models of pulse distributors were developed and built for the cases of power supply of single-phase asynchronous motors with bridge inverters of separate and individual starting and working windings, half-bridge inverters with a bipolar power source and a three-phase inverter with control according to a 180-degree control diagram. Time diagrams of visual confirmation of the system's performance according to the declared principles have been obtained. Originality. A number of original switch diagrams of the power section of the models of impulse distributors of autonomous voltage inverters are proposed, taking into account the phase shift and the duration of the switching pauses of the switching arms of the power unit to avoid emergency modes, recommendations are given on the levels of generation frequencies that are fed to the input of the combinational circuit, the prospect of using this system as part of a single-phase asynchronous electric drive with the possibility of energy-efficient control is shown.Practical value. The proposed original model solutions for autonomous voltage inverters, which are adapted to work together with a single-phase IM, can be useful for developers of converter technology and become visual material for their use in the educational process for training specialists in specialty 141 "Electric power engineering, electrical engineering and electromechanics".

Расчетная методика определения потерь в асинхронном тяговом двигателе электровоза при изменяющейся нагрузке

Purpose: In the work [1], an experimental study of the energy efficiency of electric locomotive asynchronous traction drive under changing load has been carried out. In this article, the task is to develop a method for calculating the losses in an asynchronous traction motor (ATM) when powered by a converter, depending on the changing load. Methods: When ATM is powered by a converter and voltages and currents are non-sinusoidal, the determination of losses is a difficult problem, since a significant number of factors must be taken into account. An approach based on the separation of losses and the utilization of experimental results has been employed. To calculate the losses, an approach used in the theory of electrical machines has been applied. It is based on the separation of losses, which consist of electrical (losses in copper), magnetic (losses in steel), mechanical and additional ones. Since the stator current contains higher harmonics, the electrical losses in the stator winding are determined taking into account the effect of current displacement. To ascertain the magnitude of magnetic losses, the harmonic composition of the flux linkage in the air gap is determined, the losses from each harmonic are calculated and summarized. Additional losses in the nominal mode are considered equal to 0.5% of the ATM power. The total loss in the ATM is determined by the summation of all the specified losses. The results of the DTA-1100 type traction motors tests according to the mutual load scheme given in [1] have been used as initial information for calculating the losses. Results: First of all, the losses in the DTA-1100 traction motor have been calculated when operating in the nominal mode. The obtained efficiency value, equal to 0.962, is in good agreement with the passport data of the engine, which is declared as 0.96. Further, the losses in the ATD when operating in variable modes are determined by calculation. A pattern of calculated losses depending on the power on the motor shaft has been established, which practically coincide with the losses found during tests on the stand, in the entire range of loads. Practical significance: The proposed method is inherently universal, and the reliability of the results obtained is confirmed by comparison with the experiment. The technique can be used to determine the energy efficiency of asynchronous traction motors of domestic electric and diesel-electric locomotives and electric trains.

Application of hybrid excitation in a DC motor for drive of transport rolls in metallurgical industry

Purpose. To determine the effectiveness of the application of hybrid excitation for DC motors of medium power. Estimate the influence of the location of the permanent magnet of the main pole core on the magnitude of the magnetic flux created by it. Methodology. The classical theory of electric machines, the calculation of the magnetic field by the finite element method and analytical comparison were used to conduct the research. Results. The feasibility of using hybrid excitation for DC motors of medium power has been confirmed. The use of hybrid excitation in an experimental direct current motor made it possible to increase the excitation magnetic flux by 11%. This will make it possible to reduce the current load of the excitation winding, increase the reliability of the motor and reduce electrical losses on the excitation. The optimal location of the permanent magnet, according to the criterion of the maximum magnetic excitation flux, is its location at the main pole shoe along the air gap. Originality. The difference between the conducted research and others is that the condition of the research was to keep the dimensions of its motor, the excitation winding and the interpoles winding unchanged. Practical value. The obtained results will allow the designers of dc motors with hybrid excitation to avoid wrong decisions during further research and development of these motors.

Digital Induction Motor Model Based on the Finite Element Method

This article presents the design of a drive system for robots and manipulators, which is based on the finite element method of an induction motor. The design process involves constructing a computer-aided design (CAD) model of the induction motor, which enables the generation of design documentation and control programs for computer numerical control (CNC) tools for manufacturing motor parts or conducting further research. A CAD model is developed for performing a finite element analysis of the motor in the SolidWorks software based on the popular AIR63V2 motor. The design of the motor’s housing, rotor, and stator is developed. Additionally, the electrical parameters of the motor are calculated using Ansys Electronic Suite—Maxwell RMxprt, utilizing the classical analytical theory of electrical machines and the equivalent magnetic circuit method. This takes into account such effects as the non-linearity of electrical steel, the non-sinusoidality of the magnetic flux in the gap, and the displacement of electric current in massive conductors. A complete model of an induction motor for research has been created, enabling the study of dependencies of speed and electromagnetic torque of an induction motor. The natural frequency of the rotor is calculated, which ranges from 922 Hz to 1015 Hz. The obtained values of calculations of natural oscillations of the CAD model of the motor can be used for motor diagnostics. Furthermore, the created project in the Ansys software can be utilized to design an induction motor with its own characteristics, optimized for specific tasks.

Optimal tuning of PID controller for speed control of DC motor using equilibrium optimizer

The efficient and smooth operation of direct current (DC) motors is of high significance in various industrial applications. This study proposed a recent optimization technique, named equilibrium optimizer (EO) for optimal tuning of the parameters of proportional integral derivative (PID) controller to provide accurate and robust control in DC motors. Mathematical modelling of the motor was carried out in Simulink environment using basic electric machine theory. Conventional Ziegler-Nichols (ZN) technique is initially designed to tune the PID controller parameters, an optimization model based on the minimization of integrated absolute error and named EO-PID is formulated and subsequently implemented to optimize the tuned parameters obtained using the ZN-PID controller. Simulation results showed that there is a significant reduction in terms of rise time, settling time, overshoot and mean square error using the proposed EO-PID tuning model as compared to the ZN-PID technique. The result also showed that the proposed EO-PID model gives a better dynamic performance as it eliminates the oscillatory response common with most conventional control techniques. The results of this study have established EO as an effective optimization technique for optimal tuning of PID controller parameters, and can therefore be used by machine operators for various industrial applications.

СПОСОБЫ И СОВРЕМЕННЫЕ УСТРОЙСТВА ПЛАВНОГО ПУСКА ВЫСОКОВОЛЬТНЫХ ДВИГАТЕЛЕЙ

The relevance In today's industry, a lot of high-voltage electric drives are used. Highvoltage electric motors are used in oil and gas production, transportation, chemical and oil refineries, energy and water supply. However, during direct start of high-voltage motors, shock mechanical and electrical loads occur on the motors themselves, connected technological mechanisms and the electrical network. In pipelines during direct starts of pump drives, hydraulic pressure waves can occur, leading to the destruction of pipes and their joints. The motor winding during one start-up can heat up to critical temperatures, which causes aging of the insulation, as well as the impossibility of restarting for several hours. Therefore, the introduction of devices for scheduled start-up of high-voltage motors allows not only to reduce mechanical and electrical loads, but also to extend the life of motors and equipment. Aim of research It was necessary to consider the existing methods of starting highvoltage synchronous and asynchronous motors, as well as to analyze the soft starters manufactured by the industry and their characteristics. Research methods The provisions of the theory of electrical circuits, the theory of electrical machines and the theory of electric drive were used. Results In the course of the work, the existing methods for starting high-voltage motors were considered, their advantages and disadvantages, and the complexity of implementation were analyzed. The modern soft starters produced by the industry and their characteristics are analyzed.

НАСТРОЙКА И ИССЛЕДОВАНИЕ РЕЖИМОВ РАБОТЫ НАБЛЮДАТЕЛЯ УГЛОВОЙ ЧАСТОТЫ ВРАЩЕНИЯ РЕГУЛИРУЕМОГО ЭЛЕКТРОПРИВОДА ПОСТОЯННОГО ТОКА

In modern closed-loop controlled electric drives used in manufacturing, the use of speed, current, torque, and other technological variable sensors is required. In some cases, indirect estimation of the electric drive state vector is required, when the use of technological parameter sensors (primarily speed sensors) is difficult or impossible. One of the problems is the length of the information cable in the feedback channel from the actuator to the power converter, which makes it difficult to use direct measurement methods. There are also difficulties in using sensors in an aggressive environment. For example, in the coal mining industry, electric motors or the entire electric drive are often located in an explosion-proof enclosure, and installing additional sensors will require expensive modernization of the entire system. State observers in sensorless electric drives allow restoring unmeasurable state vector components based on measured electrical signals in the power converters of the electric drive. From the perspective of a closed-loop controlled electric drive system, the main feedback is the feedback on the angular rotation frequency. Electric drives based on separately excited DC motors (SEDC) are simpler to investigate and implement such systems. The linearized mathematical model of an SEDC contains a relatively smaller number of differential equations compared to variable frequency drives due to the presence of independent channels for forming magnetic flux in the air gap and electromagnetic torque, which simplifies the analysis and synthesis of sensorless control systems using speed observers. Researching the observer of angular rotation for DC electric drives allows for developing design skills on a simpler system before moving on to variable frequency drives. Research in this area for both DC and AC electric drives is promising because it allows for an increased range of regulation and accuracy of the output coordinate in sensorless electric drives at the required level. This article is dedicated to the study of the properties of speed observers for DC electric drives with independent excitation of various structures. Aim of research Analysis of rotation frequency observer structure in DC motor drives with error reduction based on the proportional principle. Research methods Theoretical and experimental research methods were used in this study. Theoretical methods included the theory of automatic control, state observer theory, theory of electric drives, theory of electric machines, mathematical modeling, systems of differential equations, Laplace transforms, and numerical methods for solving differential equations. Experimental studies were conducted on a software-hardware complex, where the genetic algorithm method was used to identify the parameters of the electric machine equivalent circuit. Results Analytical expression for the characteristic equation roots for the investigated structure of the DC motor drive's speed observer was obtained. Based on this expression, stability criteria and trends in changes of the quality indicators for the angular velocity estimation were determined with varying observer coefficients.

Experimental research of transition processes of asynchronous motors of belt conveyors on mathematical modeling

The purpose of the study. increasing the performance of belt conveyors and reducing transportation costs based on the developed mathematical modeling of transient processes of asynchronous motors of open-pit conveyor transport. The object of the research is the operating modes of asynchronous motors of belt conveyors of mining enterprises. The subject of research is the starting and braking modes of operation of asynchronous motors of belt conveyors of mining enterprises. Research methods are based on the modern theory of electrical machines, methods of linear and nonlinear mathematical programming, mathematical statistics, as well as methods of system analysis. The practical results of the study are as follows: the actual coefficient of resistance to the rotation of the conveyor rollers and the coefficient of resistance to the movement of the belt, leading to a decrease in the tractive effort, were determined; a method was developed for determining the additional power consumption of electric motors of belt conveyors, taking into account the overall volume, weight and speed of transported lumpy cargo; a mathematical model of braking and starting modes of induction motors of belt conveyors of mining enterprises was developed, taking into account the resistance coefficient of the belt and rollers.

Определение сопротивления в цепи тяговых электродвигателей по данным микропроцессорных систем управления

Purpose: To develop methodology for determining the actual resistance of traction electric drive (TED) circuits of a locomotive with electric power transmission and with refined calculation of voltage losses of a collector-brush apparatus according to microprocessor control system data. These data are necessary for calculating actual traction characteristics of a locomotive as well as its braking characteristics in electric braking modes. Methods: Methods of electric machine theory, statistical processing and regression analysis of experimental data were used. Results: Based on the statistical analysis of registration data of on-board diagnostics subsystem of 20 sections of 2TE116U and TEP70BS diesel locomotives, methods for determining resistance factual value for traction electric drive circuit as well as methods of refined calculation for voltage losses in a collector-brush apparatus are proposed and justified. The hypothesis on distribution normal law for the value of resistance and the possibility to use its mathematical expectation as an estimated value is confirmed. The limits of resistance possible changes for TED circuits of diesel locomotives 2TE116U and TEP70BS have been established. Practical significance: The results obtained allow us to clarify energy loss amounts in a locomotive traction drive when calculating its traction and braking characteristics. Data on the limits, allowed in exploitation, of active resistance change for TED serviceable chains may be used for operative diagnostics of locomotive power circuit.

Induction Motors Technical Condition In-Service Testing Methods

The article describes methods for in-service diagnostics of the technical condition of induction motors, which are the most widely used type of electromechanical systems. By now, a large number of various studies on this matter have been published. It is stated that the accomplished studies implement an "external" approach to solving the problem, which consists in deriving a diagnostic conclusion based on an analysis of changes in the electric motor external characteristics in one of its operation modes. In addition, these studies are based on two-dimensional models of the classical theory of electrical machines, which does not allow them to adequately reflect situations of multidimensional distribution of electromagnetic quantities in a vector space. These circumstances generated the need to develop more advanced diagnostic methods, called topological ones. Topological diagnostics methods are theoretically substantiated based on the ideas about the IM multidimensional vector space. It is shown that the parametric properties of the vector space and first of all of its working area, have a key influence on the electromechanical energy conversion efficiency. Two methods for testing different areas of the vector space are outlined. In the first case, the space working area is tested for parametric uniformity and operational stability. The results of three experiments provide unbiased and sufficient information about the degree of its homogeneity, about the changes that have occurred during the operation, and about their rates. The testing makes it possible to draw well-grounded conclusions about the electric motor active part technical condition and the degree of its criticality. In the second case, the vector space phase coordinates are tested for parametric uniformity and operational stability. The results presented testify that the proposed testing scheme is sensitive to phase parameter deviations. This is facilitated by the differential principle of its construction. The signal in a short-circuited phase, which appears in the case of a parametric phase imbalance, serves as its clear indicator. The presented mathematical modeling data confirm the efficiency of the proposed testing methods.

Determination of the Rational Mode of Mutual Loading of Traction Engines of Main Electric Locomotives

Purpose. The actual state of many of the existing testing stations for traction electric machines does not meet modern requirements for the organization of repair and technical control. At most of these stations, mutual loading stands with low energy efficiency are used. The purpose of the work is to determine the rational mode of loading electric traction machines, which will ensure a decrease in the total power of the power sources of the test station, an increase in energy efficiency and the quality of tests. Methodology. The methodological basis of the work is the general theoretical provisions and principles of the systematic approach of theoretical electrical engineering, theoretical mechanics, the theory of electric machines and converters. The substantiation of the energy and electromechanical principles of mutual loading of traction electric machines is performed using the basics of generalization and systematization of physical quantities and concepts, the theory of electric circuits, the theory of mechanical systems, and the theory of electric machines. The analysis of thermal processes and energy parameters of the electric machine test system was performed using the theory of heating a homogeneous solid body and known methods of calculating thermal circuits. The results of theoretical studies have been confirmed experimentally. Findings. The analysis of the expression for determining the energy efficiency coefficient of heating the windings of traction electric machines, obtained in the work, shows that the starting current is the most rational when testing the traction motors of electric rolling stock of mainline transport for heating. The use of this load current allows reducing the electricity consumption for tests by 20-30% (compared to the hourly mode) without reducing the quality of tests, as well as reduces the time of heating tests by three to four times. Originality. The expediency of conducting the heating tests of traction motors of main electric rolling stock with a load current equal to the current of the start-up mode has been scientifically substantiated, which ensures the energy efficiency increase of the tests and a corresponding reduction in the total cost of electricity for acceptance tests. The method of analytical determination of the weighting coefficients of influence on the temperature excess of the armature winding of electric losses was proposed, the use of which allows evaluating the influence of the mutual loading modes of the tested traction electric machines on the discrepancy degree of the thermal loads of their armature windings. Practical value. The results of theoretical studies allow determining the rational modes of mutual loading of traction electric machines, which make it possible to reduce the electricity consumption for conducting their heating tests and shorten the time of conducting heating tests. In addition, it becomes possible to propose a method of evaluating the quality of acceptance tests of traction electric machines, which takes into account the discrepancy degree in the thermal loads of the windings.

МАТЕМАТИЧНЕ МОДЕЛЮВАННЯ ЕЛЕКТРИЧНОЇ МАШИНИ З ТРИСТУПЕНЕВИМ ГІРОСТАБІЛІЗОВАНИМ РОТОРОМ

A retrospective review of the development of the theory and practical structures of electric machines with a three-degree-of-freedom rotor (EMTR) at the Institute of Electrodynamics of the National Academy of Sciences of Ukraine. The applications of EMTR in surveillance, tracking and stabilization systems on moving objects are listed. The relevance of the development of such machines is shown. The disadvantages of the classical mathematical model of EMTR are noted and the need to develop a refined mathematical model due to the need to develop new technology, the emergence of new materials and electronic components, as well as the growth of computing capabilities. The two main known structures of EMTR are described and the advantages of the perspective structure chosen as the basic one are listed. The model of static three-dimensional magnetic field of EMTP and the associated dynamic model in the COMSOL Multiphisics environment are substantiated and constructed for the basic structure of EMTR. The connection between the magnetostatic problem and the rotor motion dynamics problem is ensured by the fact that the data of the calculated instantaneous characteristics are transmitted in the form of approximated dependences to the dynamic problem. In the mode of free rotation without losses, the dependences of the precession angle on time, amplitude and phase of the sinusoidal current of the control winding are calculated. High accuracy of observance of the direction of precession of the axis of the rotor at observance of the corresponding initial phase of sinusoidal current of a control winding is noted. The influence of rotation windings on the moment created by the control winding is investigated. References 3, figures 8.

PROSPECTS OF USING AUTONOMOUS ELECTRIC TRAINS WITH ONBOARD STORAGE STORES

Purpose. Improving the efficiency of passenger traffic on non-electrified sections of the railway of Ukraine by optimizing the structure and creating principles for building a traction electric drive of a promising autonomous electric train powered by traction engines from the system of onboard storage of electricity. Methods. The methodological basis of the study are the general theoretical provisions and principles of the system approach of theoretical electrical engineering, theoretical mechanics, theory of electrical machines and converters. The basic principles of management theory and the basics of decision theory are used. Results. The general principles of construction of the traction electric drive of the perspective autonomous electric train with power supply of traction engines from onboard energy storage devices are formulated. The functional scheme of the traction electric drive of the perspective autonomous electric train is offered, the analysis of work of the electric drive in the modes of traction and regenerative braking is carried out. The mass parameters of two types of energy storage devices, namely electrochemical batteries and supercapacitors, have been determined. The basic requirements to the system of automatic control of the traction drive of the electric train are formulated. It is shown that in the future the use of autonomous battery electric trains will be technically possible and economically justified on non-electrified sections of Ukrzaliznytsia.

ENGINEERING PRACTICE OF SETTING A FIELD ORIENTED CONTROL SYSTEM FOR INDUCTION ELECTRIC DRIVE OF PIPELINE VALVES BASED ON EQUIVALENT CIRCUIT PARAMETERS, ESTIMATED BY FALLING PHASE CURRENT CURVE

To support modern requirements for an induction electric drive of pipeline valves, the most promising is the organization of a filed oriented control system, the setting of which is extremely difficult without the parameters of the equivalent circuit of an induction machine. This article provides a technique of setting a field oriented control system for induction electric drive of pipeline valves based on equivalent circuit parameters, estimated by falling phase current curve. The main aim of the research is to test the functioning of an induction filed oriented electric drive using a load stand, the setting of which is made on the basis of parameters previously estimated by falling phase current curve. Methods. To achieve the goal of the research, theoretical and experimental research methods were used. Theoretical research methods include the theory of electric drive, the theory of automatic control systems, the theory of electrical machines. Experimental research were carried out using a load stand that provides the required level of load on the shaft of the tested induction machine. Results. Suggested the technique of setting a field oriented control system for induction electric drive of pipeline valves based on equivalent circuit parameters, estimated by falling phase current curve. Relative values of deviations of current, speed and torque are obtained at the nominal level of load on the shaft of an induction machine. The applicability of the proposed technique using a loading stand was confirmed.

TECHNIQUE OF SETTING UP A PIPELINE VALVE ELECTRIC ACTUATORS CONTROL SYSTEM USING THE EQUIVALENT CIRCUIT PARAMETERS, ESTIMATED BY FALLING CURRENT CURVE

To support modern requirements for an induction electric drive of pipeline valves, the most promising is the organization of a filed oriented control system, the setting of which is extremely difficult without the parameters of the equivalent circuit of an induction machine. This article provides a technique of setting a field oriented control system for induction electric drive of pipeline valves based on equivalent circuit parameters, estimated by falling phase current curve. The main aim of the research is to test the functioning of an induction filed oriented electric drive using a load stand, the setting of which is made on the basis of parameters previously estimated by falling phase current curve. Methods. To achieve the goal of the research, theoretical and experimental research methods were used. Theoretical research methods include the theory of electric drive, the theory of automatic control systems, the theory of electrical machines. Experimental research were carried out using a load stand that provides the required level of load on the shaft of the tested induction machine. Results. Suggested the technique of setting a field oriented control system for induction electric drive of pipeline valves based on equivalent circuit parameters, estimated by falling phase current curve. Relative values of deviations of current, speed and torque are obtained at the nominal level of load on the shaft of an induction machine. The applicability of the proposed technique using a loading stand was confirmed.

Method of Cylindrical Linear Induction Motor Equivalent Circuit Parameters Determination and Performance Calculation Algorithm

Cylindrical linear induction motors (LIM) are currently used in many industrial applications. Task of modeling of electrical machine is of great importance for optimization of processes of design and manufacture of engines with optimal technical characteristics. Traditional approach of construction of mathematical models of asynchronous machines based on classical theory of electrical machines, in comparison with methods of field theory and numerical methods, is much simpler. Structurally cylindrical LIM are distinguished by the absence of transverse edge effects, which contributes to the use of the methods of the classical theory of electrical machines for construction of their mathematical models. In this paper proposes an analytical method of calculation of parameters of equivalent circuit and operating characteristics of cylindrical LIM. In work engine was studied, movable part of which is made in the form of solid steel bar with a copper coating. Equivalent circuits of linear induction motors of various designs (one-sided, two-sided, cruciform, cylindrical) are considered, and assessment of the possibility of their application for research motor is made. Work of cylindrical LIM on industrial mechanisms is characterized by relatively small value of working stroke. For such engines, it is difficult to carry out standard tests, in particular idle stroke test, in order to obtain data for calculation of parameters of the equivalent circuit. The paper proposes a method of experimental determination of parameters of the equivalent circuit. Stator active resistance is measured at direct current, and stator reactance is measured using out-of-rotor method. The remaining parameters of equivalent circuit are calculated according to short circuit experience and engine work mode without load (is taken as an idle stroke experience). It is shown that exact G-shaped equivalent circuit, when calculation of parameters of which active and reactive components of correction factor and active resistance of magnetization branch are taken into account, provides acceptable accuracy in determination of values of equivalent circuit parameters. Algorithm of calculation of work characteristics of cylindrical LAM based on equivalent circuit data is presented. Comparison of calculated and experimental data showed satisfactory results, error is not more than 7%. A new model for decomposition of the total power losses, which includes four components is proposed. Each of the components of the proposed model has a certain physical meaning due to the nature of electromagnetic processes in a three-phase four-wire system. Definitions to describe each of the proposed components are formulated. It is shown that each of supplementary components of the total loss power is proportional to the minimum possible loss power and to the square of the RMS value of the power, which is caused by its occurrence in three-phase four-wire power supply system, and it is inversely proportional to the mean square of the net power loss. The synthesized Matlab-model for verification of the four-component structure of power losses showed a high degree of its adequacy. The proposed model allows us to rethink the description of power losses in three-phase AC circuits and can be used in specialized measuring instruments for electrical networks monitoring. Using the information obtained in the monitoring process, it is possible to plan technical measures to reduce losses of electrical energy in the power supply system, as well as to estimate the capital costs of these measures.

The determination of induction motor losses in steel taking into account its saturation

PurposeThis paper aims to work out a method for calculating losses in induction motor steel taking into account its saturation.Design/methodology/approachThe theory of electric machines is applied during the analysis of induction motor equivalent circuits. The theory of Fourier series is used to determine the harmonic components of voltage, current and power. Instantaneous power theory and trigonometric transformations are used to solve algebraic and differential equations and their systems. The methods of approximation and interpolation are applied to obtain analytical expressions from the experimental data. Experimental research was carried out to verify the reliability of theoretical provisions and research results.FindingsA method for assessing an induction machine steel as a function of the generalized electromotive force has been proposed. It allows taking into account higher harmonics of the current, which are caused by the presence of nonlinearity of an induction motor magnetic circuit.Practical implicationsThe obtained results can be used in calculating the energy characteristics and operating modes of an induction motor, as well as in the construction of control systems.Originality/valueA method for determining the losses in the stator steel of an induction motor, using a generalized electromotive force, has been proposed for the first time. It enables taking into account the currents flowing both in the stator circuit and in the rotor circuit.