Analysis of Control Methods for the Traction Drive of an Alternating Current Electric Locomotive

The analysis of operating conditions of traction drives of electric locomotives with asynchronous traction motors has been carried out. It was found that during operation in the output converter of an asynchronous motor, defects may occur, which leads to asymmetric modes of its operation. Models of a traction drive of an electric locomotive with asynchronous motors with scalar and vector control of the output converter are proposed, taking into account asymmetric operating modes. As a result of the simulation, the starting characteristics of the traction drive were obtained for various control methods both in normal and emergency modes of the drive. For the drive-in emergency mode, the following cases were investigated: the balance of the converter output voltages and the turn-to-turn circuit of 10% of phase A winding of the motor stator; imbalance of the output voltages of the inverter and an intact motor; imbalance of the output voltages of the converter and interturn short circuit of 10% of phase A winding of the motor stator. Comparison of the simulation results have shown that in emergency modes in the traction drive, the torque ripple on the motor shaft in the drive with vector control is 13% less, and in scalar control, the phase current unbalance coefficient is 22% less. The results of this work can be used to study the influence of the output converter control methods on the energy efficiency indicators of the traction drive of an AC electric locomotive.

Research of current distribution by phases in asynchronous electric motor with a combined winding

THE PURPOSE. The asynchronous electric motor with a squirrel cage rotor is widely used in the electric driven industry and agricultural machinery. One of the possible ways to improve its energy characteristics is to use a combined 12-zone stator winding instead of the standard 6-zone one. However, in a combined winding with a parallel connection of the «star» and «delta» phases, the phases may not be loaded equally. Therefore, the main purpose of the work under analysis is to study the distribution of currents between the phases of the «star» and «delta» in the asynchronous motor with a combined winding.METHODS. The study was performed on the AIR71V4 engine, rewound onto a combined winding, in which the real ratio of the active resistances of the «delta» and «star» turned out to be 7% less than the theoretical one. The tests were carried out in no-load and short-circuit mode when powered from a three-phase network, as well as in short-circuit mode when one of the line wires is broken.RESULTS. The work gives the values of the currents flowing through the phases of the combined winding. For the experimental sample, the deviation of the obtained currents from the theoretical values is determined. Equations of currents are obtained when one of the linear wires is broken. Schemes for switching on the main contacts of a thermal relay for a motor with a combined winding are proposed.CONCLUSION. The results of the study showed that in an asynchronous motor with a combined winding, in which the real ratio of the active resistances of the «delta» and «star» is less than the theoretical one, the current is not proportionally distributed over the phases. The most preferred circuit for switching on a thermal relay is one in which its main contacts are connected to the «delta» phases, and the thermal relay must be three-pole.

Load switching between main power grid to the backup grid by standard automatic transfer switch

PURPOSE. To develop a variant of the algorithm for the automatic input of the reserve, which consists in transferring the load in case of emergency situations, to make a simulation model in the MatLab® environment corresponding to the developed generalized electrical scheme of the system.METHODS. When solving the problem, the method of digital modeling was used, which consists in the maximum approximation of the system under study to a real object, implemented by means of MatLab.RESULTS. It is proposed to study the methods of synthesis of digital models of compensation of voltage drops by the example of a study of an automatic reserve transfer system, demonstrating an approach to modeling this system. When developing models in the MatLab environment, the parameters of real technical elements and devices and their digital analogues are taken into account. The issue of creating a digital model of an electric drive system, including a model of an asynchronous motor with a short-circuited rotor, is considered. The result, after final refinement, can be used to design a real system in production conditions.CONCLUSIONS. The developed model of the automatic transfer switch system is operable, the time indicators are satisfactory for systems that do not make excessive demands on performances and time intervals. For systems that are sensitive to current inrushes during load transfer, some improvements are required, which are reduced to the implementation of a high-speed automatic switch system. The development of this system is currently at the research stage, namely, the compilation of a load transfer logic that takes into account the phase matching of electrical circuits.

ANALYSIS OF THE STRESS-STRAIN STATE OF AN ASYNCHRONOUS MOTOR WITH A SHORT-CIRCUITED ROTOR UNDER AXIAL LOADS

A comparative description of the most popular and professional 3D modeling packages using the finite element method in solving problems is given. The choice of using the SolidWorks Simulation package at this stage of research is justified. Its main advantages are given. A 3D model of a real functioning asynchronous motor has been designed and modified to perform linear displacement operations. A static analysis of the strength of an asynchronous motor with linear displacement of the actuator using the plug-in module SolidWorks Simulation was performed. A direct analysis of the obtained result of the stress-strain state of the engine is carried out. Conclusions are drawn about its suitability to work with axial loads. The main directions of subsequent research of asynchronous motors with a short-circuited rotor under axial loads are determined.

The effect of the initial size on the height of the crank press die

The expansion of the technical and technological capabilities of forging and stamping machines and equipment can be carried out through the introduction of new designs of actuators with wide functionality. These developments require solving the problems of kinematic synthesis and analysis of mechanisms. In this work a comparative analysis of the endurance indicators of a crank press with the mechanism for transforming the motion of Stephenson II depending on the elastic compliance of the connecting rods and the deformation of the forging was shown. In this regard, the features of the kinematics of a crank press driven by an asynchronous motor taking into account the flexibility of the connecting rods and the workpiece was investigated.

SEARCH FOR WAYS TO IMPROVE THE TRACTION PROPERTIES OF LOCOMOTIVES AND TRACTION DRIVE DESIGN

The work objective is to increase the traction properties of locomotives without the use of traction drives with asynchronous traction motors and pulse width modulation. Research methods: methods of physical and field experiments, analytical methods for calculating the dynamics of the rolling stock. Conclusion: based on the conducted research, it is proposed to perform a promising diesel locomotive in the form of two sections on three two-axle bogies and a booster on two two-axle bogies, as well as to carry out experimental design work to develop an arc-type stator asynchronous motor and traction drives of a diesel locomotive using it.

Checking the adequacy of polynomial dependencies of a single-phase asynchronous motor without external phase-shifting devices for ship automation systems

Статья посвящена сравнению результатов расчётов полиномиальных зависимостей однофазного асинхронного двигателя, полученных с использованием методов планирования эксперимента, с математической моделью построенной с помощью программ на ЭВМ на языке программирования Python. Актуальность работы заключается в том, что задачи аппроксимационного типа не всегда возможно решить, используя ЭВМ, поэтому исследователи часто применяют методы планирования эксперименты для решения таких задач и после уже стоят математическую модель на ЭВМ и проверяют адекватность полученных результатов. В результате в статье авторами предоставляется план проверки адекватности полиномиальных зависимостей однофазного асинхронного электродвигателя без внешних фазосдвигающих устройств для систем судовой автоматики. По итогу выполненной работы авторы приходят к выводу об адекватности построенной математической модели на ЭВМ с использованием языка программирования Python. The article is devoted to the comparison of the results of calculations of polynomial dependencies of a single-phase asynchronous motor, obtained using methods of experiment planning, with a mathematical model built using computer programs in the Python programming language. The relevance of the work lies in the fact that problems of the approximation type are not always possible to solve using a computer, therefore, researchers often use methods of planning experiments to solve such problems and after that they already have a mathematical model on a computer and check the adequacy of the results obtained. As a result, the authors provide a plan for checking the adequacy of the polynomial dependencies of a single-phase asynchronous electric motor without external phase-shifting devices for ship automation systems. As a result of the work performed, the authors come to the conclusion about the adequacy of the constructed mathematical model on a computer using the Python programming language.