The aim of this study is to investigate and determine the effect of accounting for the non-uniform distribution of magnetic induction (by detailing the stator tooth model) on the calculation results of magnetic losses in the stator teeth of a switched reluctance motor in quasi-steady-state modes. To achieve this goal, dependencies of phase flux linkage, electromagnetic torque of the motor, and additionally, dependencies of the root mean square values of magnetic inductions in stator tooth elements on the rotor angle and current have been determined using the finite element method. An investigation of dynamic modes of the switched reluctance motor based on an improved simulation model has been conducted at various values of constant load torque. Dependencies of magnetic inductions over time for each stator tooth element for the studied quasi-steady-state operating modes have been obtained. Magnetic losses have been calculated, taking into account the maxima of the temporal dependencies of root mean square values of magnetic induction in stator tooth elements. The most important outcome is a quantitative assessment of the influence of the non-uniform distribution of magnetic induction on the calculated value of magnetic losses based on the detailing of the stator tooth model in the operational modes of the switched reluctance motor compared to the traditional approach. The significance of the work lies in developing an approach to refining the calculation of magnetic losses by considering local saturation in the magnetic circuit during the operation of the switched reluctance motor.
The expansion of the concept of power factor, that defined for circuits with periodic voltage and currents, to three-phase circuits with asymmetric non-periodic voltage and currents is justified.It is shown that this concept is advisable both when considering transients these occur in electric networks in the start-up modes of powerful asynchronous machines, and when evaluating the effectiveness of the use of various technical devices for these modes for correcting.References 6, figures 2.
For the purposes of optimal design of innovative constructions of induction motors, an approach to their mathematical modeling is presented, based on the use of the proposed weakly-coupled parameterized circuit-field mathematical model of the induction motor. The essence of this model and its difference from the well-known circuit-field model are described. The particular feature of the developed model is the determination of operational parameters and parameters of the equivalent circuit by sequentially solving the equations of the circuit and field mathematical models, respectively. Using a numerical study of the nominal mode of a series-connected induction motor as an example, the developed mathematical model is tested, assessing the accuracy and time complexity of the obtained results.
The efficiency and adequacy of mathematical models of induction motors for dynamic operating conditions are improved due to used dependences for varied electromagnetic parameters.The dependences are based on the results of field analysis.The mathematical models with single-dimensional approximation of parameters are developed.This simplifies the field analysis 1 / 3 N1 st7and formation of approximating dependences with continuous derivatives.The relationship between given functional dependences of electromagnetic parameters and the adequacy of mathematical models for static and dynamic conditions is studied.The expressions and method are proposed to determine the correction coefficients that improve the adequacy of the mathematical models for dynamic conditions with single-dimensional approximation of parameters.References 8, figures 3.
The work highlights the problems of using coolants in vehicles equipped with internal combustion engines, as well as their compatibility with each other. Since the problem of choosing the latter is due to the fact that the range of coolants on the market is extremely wide. Each type contains a certain set of additives that affect its main characteristics: freezing and boiling temperatures, density, etc. And the single color of the coolant does not guarantee that these antifreezes belong to the same group. An analysis of the works of leading domestic and foreign scientists devoted to the problem of choosing and using coolants for internal combustion engines of vehicles was carried out, which showed that the actual problem is the correct selection of coolant for a specific vehicle and the corresponding conditions of its operation. The main factors affecting the use of cooling liquids for internal combustion engines, as well as their compatibility with each other, are highlighted. Recommendations are given for the selection of coolants and their use, the main factor for the selection of coolant for internal combustion engines is the standard according to which the liquid is manufactured. It is not necessary to get attached only to the color, but to select the type - based on the tolerances of the car manufacturer of a specific vehicle. It is shown that there is no clear and unequivocal answer to the question of which antifreeze is better. The fact that lowrid coolants are the best option is obvious, but it is necessary to take into account the requirements of the car manufacturer first of all. The range of coolants on the automotive market of Ukraine is huge. In addition to the fact that each type of liquid contains its own complex of additives, it also differs in its main characteristics: density, boiling and freezing points. Therefore, an obvious answer arises - use only fluids recommended by the car manufacturer.
Opportunities of complex research of asynchronous motors with internal indemnification of a reactive power are shown at use of universal model of asynchronous motors of electromechanical systems for imitating and structural modelling. The example of mathematical model of the compensated engine with the compensating field isolated from a network closed on condensers is shown.
A complex mathematical model of the electromechanical system of the gravity energy storage of a wind power plant and the expression of the criterion of its optimal design as the ratio of the efficiency of the system according to the final result to the value of energy resource are developed. The model is implemented in the Matlab simulation system for optimization research in conditions of constant and variable wind speed taking into account the mutual influence of system components: electric generator and motor, reducers, electric network, power frequency converter, hoisting installation. On the example of a system with a capacity of 40 kW, the patterns of change of complex energy coefficients are studied, the efficiency of the developed means of optimal design is substantiated.
Developed a complex mathematical model of the electromechanical system of oil production by means of the submerged centrifugal pump. Received an expression of the complex criterion of efficiency of system taking into account stages of extraction and repair of a well, as a ratio of volume of extracted oil to the consumed energy during a cycle of the analysis of processes. Mathematical model of the system: asynchronous motor - pump - hydraulic network is implemented in the simulation system and provides a study of the relationship between the amount of energy consumed and the efficiency of the system - the volume of oil produced. The developed complex mathematical model provides optimization researches taking into account nonlinear properties of components of system, their mutual influence. The initial information in determining the design parameters of the model components is the power of the induction motor of the pump, the geodetic height of the oil, the maximum efficiency of the pump, as well as for the point of maximum power of the pump operating range: engine load, hydraulic efficiency of the well and pipeline. The pressure characteristic of the pump is approximated at points of limits of the working range. Approximation of the pressure characteristic and efficiency of the pump is carried out taking into account changes of sizes of giving and speed of rotation. According to the simulation results, recommendations for improving energy efficiency using means of minimizing hydraulic losses in the process of well repair: optimization studies of the dependence of the change in the value of the energy efficiency coefficient as a function of production period while varying the duration of the repair period. For the example studied, increasing the repair time by 2.5 times reduces the overall energy efficiency of oil production by 20%. Also, energy efficiency decreases by 5% by reducing the extraction period from the optimal by 35% and by increasing by 65%.
