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This article presents an analysis of the causes behind the development of asymmetric modes in a traction drive system that features direct torque control (DTC) of a rolling stock with asynchronous traction motors. The development of asymmetric modes in the traction drive system was found to be caused by the asymmetry of the supply voltage system, the asymmetry of the traction motor windings, and transient processes triggered by a change in the inverter supply voltage and variation in the traction motor load. At the same time, the asymmetric modes caused by the asymmetry of the feed voltage system and the windings of the traction motor are the emergency modes. The influence of the asymmetry of the feed voltage system and asymmetry of the windings of traction motor on the starting characteristics of the phase currents and flux linkages of the stator in the steady-state mode was investigated. In these cases, the ratio of the amplitudes of phase currents and flux linkages of the stator of different phases was found to be constant. The effect of a variation in the feed voltage and load acting on the motor shaft on the starting characteristics of phase currents and flux linkages of the stator was investigated in the case of absence of the emergency modes. In these cases, the ratio of the amplitudes of phase currents and flux linkages of the stator of different phases was found to not be constant. The amplitudes of the phase current and stator flux linkage were proposed as criteria for diagnosis and identification of asymmetric emergency modes. An algorithm and a structural scheme have been proposed for the diagnosis of emergency asymmetric modes in the traction drive system with direct torque control. Modifications to the traction drive system with direct torque control are suggested in order to diagnose the presence of faulty asymmetric modes and identify the damaged traction drive element.

An analysis of the operating conditions of the traction drives of an electric rolling stock with asynchronous traction motors was conducted. In the process of operation, the electric traction drive with both direct torque control and vector control was found to possibly experience unstable modes, both in terms of power supply and load. The models of electric locomotive traction drives with asynchronous electric motors with either vector or direct torque control were adapted to account for the possible presence of the aforementioned operational factors. As a result of the modeling, the starting characteristics of the electric traction drives with different control systems were obtained both in the absence and in the presence of power supply and load disturbances. The following cases were investigated for the drive with vector and direct torque control in the absence of power supply and torque disturbances: drive output at the rated speed of rotation of the electric motor shaft; 10% reduction in the rated speed; 10% increase in the rated speed. The comparison of the results obtained has demonstrated that, at lower than nominal frequencies, the electric traction drive with direct torque control has higher accuracy in its regulation of the rotational speed and torque, lower power consumption from the power supply, lower torque overshooting, but a higher level of torque pulsations than the electric traction drive with vector control. Meanwhile, at higher than nominal frequencies, the vector control has higher accuracy in its regulation of the speed, lower torque overshooting, shorter duration of transient processes, and lower torque pulsations than the direct torque control. Moreover, as a result of the investigations, the traction drive with direct torque control has been found to be more resistant to power supply and load disturbances. The results of this work are applicable to the investigation of the influence of electric traction drive control methods on the energy efficiency of the traction drive of an electric locomotive with an alternating current (AC).

Operation modes of rolling stock at mining enterprises are considered and analyzed. The justification of the need to replace it with a modern specialized electric locomotive for quarry railway transport, equipped with an asynchronous traction electric drive and an on-board energy storage system, is presented. The determination of the parameters and structure of the on-board energy storage system, based on the condition of power compensation with limited power consumption from the traction network and ensuring the autonomous movement of the electric locomotive, is considered. This study was carried out by modeling the processes of energy exchange in the traction system of an electric locomotive. The use of lithium cells and supercapacitors in energy storage is considered. Variants of the hybridization of energy storage were studied from the standpoint of minimizing the weight, size, and cost indicators. It was established that reducing the mass of the energy storage device, which includes lithium cells and supercapacitors, leads to an increase in the cost of one kilowatt-hour of energy storage capacity, which reduces the attractiveness of capital expenditures for the creation of such an energy storage device. Hybridization of the energy storage device by combining lithium cells of different types practically does not improve its weight, size, and cost indicators. The recommended option is a storage capacity of energy based on LTO elements, for which it is necessary to select elements in order to minimize weight, size, and cost indicators.

It has been proposed, in order to model an induction motor for vehicles, to employ a system of differential equations recorded in the «inhibited coordinates». To improve the algorithm robustness, the number of the system’s equations was reduced by expressing the phase currents through the phase flux linkage. The parameters of the prototype engine have been defined in line with the classical procedure. An algorithm has been constructed in order to account for the mechanical losses and power losses in the engine steel. An induction motor with symmetrical windings has been simulated in the MATLAB programming environment. The basic technical parameters for the engine were determined using the simulation model. The simulation results have been compared with the results of classic calculations. The error in determining the parameters based on the model and those calculated did not exceed 7 %. This indicates a high convergence between the simulation results and the results of calculations. It has been proposed, in order to study an induction motor with the asymmetrical stator windings, to apply the algorithm that implies accounting for a change in the mutual inductance at a change in the integrated resistance in the single or several phases of engine windings. The proposed algorithm for managing the asymmetric regime of stator windings could make it possible, without changing the structure of the model, to investigate the dynamic processes in an induction motor in case of the asymmetry of stator windings phases when they are damaged. Taking into consideration the losses of power in steel, as well as the mechanical losses, would improve the reliability of the results obtained. The error of determining the parameters of an induction motor at asymmetrical stator windings, obtained at modeling, and acquired experimentally, did not exceed 3 %, which testifies to the adequacy of the model.That would make it possible to apply the proposed simulation model of an induction motor when studying the dynamic processes in the engines used in the transportation infrastructure, in case of such a defect as the interturn short circuit in the stator windings, Предложено для моделирования асинхронного двигателя транспортных средств воспользоваться системой дифференциальных уравнений, записанной в «заторможенных координатах». С целью повышения устойчивости алгоритма сокращено количество уравнений системы путем выражения фазных токов через фазные потокосцепления. Рассчитаны параметры двигателя-прототипа по классической методике. Разработан алгоритм учета механических потерь и потерь в стали двигателя. Реализовано имитационное моделирование асинхронного двигателя с симметричными обмотками в программной среде MATLab. С помощью имитационной модели определены основные технические параметры двигателя. Выполнено сравнение результатов моделирования с результатами классических расчетов. Погрешность при определении параметров на модели и выполненных расчетным путем не превысила 7 %. Это свидетельствует о высокой сходимость результатов моделирования с результатами расчетов. Для исследования асинхронного двигателя с несимметричными обмотками предложен алгоритм, который заключается в учете изменения взаимной индуктивности при изменении комплексного сопротивления одной или нескольких обмоток статора асинхронного двигателя. Предложенный алгоритм организации несимметричного режима обмоток статора позволит без изменения структуры модели исследовать динамические процессы в асинхронном двигателе при несимметрии обмоток статора. Погрешность определения параметров асинхронного двигателя при несимметричных обмотках статора, полученных при моделировании, и снятых экспериментально не превысила 3 %, что свидетельствует об адекватности модели. Учет потерь в стали и механических потерь повысит достоверность полученных результатов. Предложенная имитационная модель асинхронного двигателя необходима при проведении исследований динамических процессов в двигателях транспортных средств при возникновении такого дефекта, как межвитковое замыкание в обмотках статора, Запропоновано для моделювання асинхронного двигуна транспортних засобів скористатися системою диференційних рівнянь, записаною в «загальмованих координатах». З метою підвищення стійкості алгоритму скорочено кількість рівнянь системи шляхом вираження фазних струмів через фазні потокозчеплення. Розраховано параметри двигуна-прототипу за класичною методикою. Розроблено алгоритм врахування механічних втрат та втрат потужності в сталі двигуна. Реалізовано в програмному середовищі MATLab імітаційне моделювання асинхронного двигуна з симетричними обмотками. Визначено основні технічні параметри двигуна за допомогою імітаційної моделі. Виконано порівняння результатів моделювання з результатами класичних розрахунків. Похибка при визначенні параметрів на моделі і виконаних розрахунковим шляхом не перевищила 7 %. Це свідчить про високу збіжність результатів моделювання з результатами розрахунків. Запропоновано для дослідження асинхронного двигуна з несиметричними обмотками статора алгоритм, який полягає у врахуванні зміни взаємної індуктивності при зміні комплексного опору однієї, або декількох фаз обмоток двигуна. Запропонований алгоритм організації несиметричного режиму обмоток статора дозволить без зміни структури моделі дослідити динамічні процеси в асинхронному двигуні при несиметрії фаз обмоток статора при їх пошкодженні. Врахування втрат потужності в сталі та механічних втрат підвищить достовірність отриманих результатів. Похибка визначення параметрів асинхронного двигуна при несиметричних обмотках статора, отриманих при моделюванні, і знятих експериментально не перевищила 3 %, що свідчить про адекватність моделі.Це дозволить застосувати запропоновану імітаційну модель асинхронного двигуна при дослідженні динамічних процесів в двигунах транспортної інфраструктури при виникненні такого дефекту, як міжвиткове замикання в обмотках статору