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.

CALCULATION OF TRACTION AND ENERGY CHARACTERISTICS ELECTRIC ROLLING STOCK WITH ASYNCHRONOUS TRACTION ELECTRIC DRIVE

The issue of determining the traction and energy characteristics of electric rolling stock with asynchronous traction drive is considered. It is noted that such rolling stock can work at any point of the traction area, resulting in the need to determine the characteristics of the rolling stock for the entire traction area. The calculation of the characteristics of the traction induction motor, which are the basis for determining the traction and energy characteristics of the electric rolling stock, is considered in detail. A procedure based on the calculation of the replacement circuit of an induction motor is proposed. The calculation of power losses due to higher harmonic voltages and currents is considered. An example of calculation of traction and energy characteristics of an DC electric shunting locomotive with a traction asynchronous electric drive is given.

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.

THE METHOD OF OBJECT MODELING IN THE DEVELOPMENT OF PATENTABLE DESIGNS OF TRACTION DRIVE MECHANISMS

Work objective is to develop a patentable design of locomotive traction drive mechanisms using the example of a suspension unit. Research methods: object modeling method, analytical methods for calculating dynamics of rolling stock. Research results and novelty: the design of the railway electric motor suspension unit, which will reduce costs in the course of maintenance and repair of a locomotive with a solid gear by increasing the reliability of the suspension unit parts, eliminating their wear, has been developed; a compensation coupling device has been devised. We will synthesize the object model of a technical system based on the identification of its typical structure by classifying technical systems. Conclusion: the application of the object modeling method together with the object model allows avoiding errors in the development of new designs of technical objects based on existing comparables and eliminates defects of the selected prototype. The use of the object modeling method makes it possible to synthesize patentable designs of the locomotive underframe mechanisms.

Model of pulsating current traction motor taking into consideration magnetic losses in steel

The aim of the work is to develop a mathematical model of the traction motor of the pulsating current of an electric locomotive taking into account the magnetic losses in the motor steel to determine the starting parameters depending on the voltage of the armature winding. Methodology. Mathematical modeling of electromagnetic processes in a traction motor of pulsating current is applied taking into account the nonlinear nature of the armature inductance, the inductance of the excitation winding and the nonlinear nature of the universal magnetic characteristic. The magnetic losses in the steel of the traction motor were taken into account by establishing the dependence of these losses on the frequency of reversal, the magnetic flux in the magnetic circuit of the motor and the geometric dimensions of the motor. Results. The mathematical model of calculation of starting parameters of the traction engine of the pulsating current of the traction drive of the electric locomotive of alternating current taking into account the equation of instantaneous value of losses in engine steel is developed. The dynamic characteristics of the traction motor with pulsating current are obtained. It allows to investigate starting parameters of the traction engine on the basis of the received mathematical model and to design elements of the traction drive of the electric locomotive according to the specification, to choose optimum design parameters. Originality. For the first time a comprehensive study of the pulsating current traction motor was carried out taking into account the nonlinear nature of the armature inductance, excitation winding inductance and nonlinear nature of the universal magnetic characteristic and taking into account the magnetic losses in the motor steel. Practical significance. The model of the traction motor of pulsating current taking into account losses in steel of the engine on the basis of the carried-out calculation is developed. Experimental studies have confirmed the adequacy of the model, which allows to apply the obtained model to develop a mathematical model of an AC electric locomotive to study the electrodynamic processes in it at different modes of operation of the electric locomotive.

Analysis of the problems of mechanical gearboxes of transport systems and their solution using a magnetic sensor

Objective: Increasing reliability of mechanical gearboxes using a magnetic sensor, which will sig nifi cantly increase the reliability of transport mechanisms and systems in general. Methods: An analysis of incidents covered in the media was carried out. Results: Conclusions are drawn about the consequences of failure of mechanical gearboxes. To prevent emergency situations caused by a breakdown of a mechanical gearbox, it is proposed to use a magnetic sensor, which allows carrying out analysis and diagnostics of the gearbox and its components during operation. A mathematical model of a magnetic sensor is compiled and a block diagram of a device for processing the output signal of the sensor modulator is presented. Practical importance: Failure of a mechanical gearbox is a common problem that leads to a stop of transport mechanisms and systems. Detection of a mechanical gearbox malfunction can signifi cantly reduce the cost of repairs, as well as prevent unexpected damage to the mechanism, which can lead to a complete stop of the transport system. The use of a magnetic sensor in the traction gearbox of an electric train will reduce the likelihood of a traction gearbox breakdown during operation and reduce the cost of repairs, increase the reliability of the traction drive, and also simplify the commissioning of new electric trains and traction gearboxes.

Vector control system of electric traction drive with power losses minimization

Based on the operating conditions analysis of electric traction drives of locomotives, it has been established that the vector control systems for an asynchronous motor fully satisfy all the requirements. On the basis of a T-shaped equivalent circuit, a mathematical model of an induction motor is presented, taking into account losses in the stator steel, the effect of the rotor current and saturation displacement. An algorithm for the formation of the optimal, from the point of view of power losses, task for the rotor flux linkage when using a vector control system with the orientation of the axes of the coordinate system along the rotor magnetic field, is developed. The limiting factors are the limitations on the current and voltage of the motor stator, the diesel generator set power. A shared control system for an electric traction drive with asynchronous motors has been developed, which provides direct control of wheel slip with a subordinate vector control system that minimizes power losses. The results of modeling in a steady-state operation and a start-up mode for an electric traction drive of a two-axle bogie with axial support and 630 kW asynchronous motors with the use of various options for organizing circuit reentrances are presented.