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).

https://www.mdpi.com/1996-1073/16/9/3689/pdf?version=1682428409

Analysis of the Efficiency of Traction Drive Control Systems of Electric Locomotives with Asynchronous Traction Motors

This article presents a model of the physical and virtual test bed for traction equipment testing for mining dump trucks with a hybrid power plant. The physical test bed is represented by two pairs of traction induction motors, each of motors has a rated power of 350 kW. In each pair of motors, one performs the role of a traction motor, and the second - the role of a load. The both pairs are connected to the traction converter, with a nominal power of 800 kW. Also the article presents a simulation model of a hybrid electric traction unit in the MATLAB Simulink environment, in which the load corresponds to the actual driving conditions of the dump truck. The simulation results are presented below.

Investigation of traction motor dynamic using computer simulation and method of mutual loading of two pair motors

Simulation based feasibility confirmation of using hybrid powertrain system in unmanned dump trucks

In the drives of high-speed devices, such as a blood centrifuge, dynamic states also play an important role in terms of the time and quality of the tests performed. The article presents the application of modified equations resulting from the mathematical model of an induction motor to model dynamic phenomena during motor start-up, both with mains supply and with frequency start-up. The applied solution considers the phenomenon of current displacement in the rotor bar and the phenomenon of saturation. The comparison of the obtained results with the experiment shows that the method is sufficiently accurate. The obtained results can also be extended to higher power machines and to modeling other dynamic states.

Dynamic Simulation of High-Speed Induction Motor

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.

/pdf/operational-diagnostics-system-for-asymmetric-emergency-1gl1mpba.pdf

Operational Diagnostics System for Asymmetric Emergency Modes in Traction Drives with Direct Torque Control

Transition to a low carbon emission transport is supported in all European countries, including Latvia. In this paper, a specific case of converting diesel bus into electric bus is analyzed. During its processing and development, real ready-made porotypes with field tests, and computer evaluation models are used.

Investigation of electrical bus traction motor dynamic using methods of physical and computer simulation

The article provides an analysis of the procedure for conducting and results of research tests of a traction geared motor box (hereinafter GMB). The traction GMB is provided for installation on a motor trolley as part of an asynchronous electric drive of a suburban electric train. Railway transmission systems operate in an environment with various sources of mechanical and electromagnetic excitations, where the possible unstable operation of the traction motor is one of the most critical indicators. This paper describes the structure and functionality of the physical test equipment and a model of a coupled system with a complete electrical circuit, including a rectifier, a DC link, a traction inverter, a motor-gear unit, and a system of mechanical connections, including flexible damper couplings and shock absorbers. This approach makes it possible to determine the intrinsic resonant frequencies of the GMB design, as well as the level of vibration activity of the GMB under dynamically changing loads. The obtained cascade characteristics of vibration activity correspond to both a long-term steady-state mode and transient mechanical disturbances during start-up, a change in rotation speed and the transition of the GMB to the run-out mode.

Carrying Out of Strength Control of Mutual Loaded Traction Geared Motor Boxes as a Part of Industrial Tests

The article deals with the problem of experimental determination of the mechanical reliability indicators of motor-gear unit of motor coaches of suburban electric trains. The range of natural frequencies of the casing is compared with the frequencies of disturbing influences. The problem of the influence of torsional vibrations of the traction motor frame as a source of additional dynamic loading of the gear casing is indicated. The value of the rigidity of fastening the casing to the traction motor depends significantly on the method of fastening. If the technology of joining the traction motor and the gearbox is not observed, the range of natural frequencies of the oscillatory system of the casing may change, while the occurrence of resonance phenomena is also possible. The paper presents the amplitude-frequency characteristic of torsional vibrations of the traction motor frame and considers the dynamic moments that occur on the gear casing during torsional vibrations of the traction motor. To reduce the level of dynamic loads on the gear housing, which contribute to the occurrence of failures, the design of the housing with shock-absorbing fastening to the frame of the motor bogie, which provides increased vibration protection of the system, is considered.

Evaluation of the Strength of Traction Geared Motor Units by Permissible Stresses and the Level of Vibration Activity

The goal is a model-experimental study of the vibration that occurs in the nodes of the motor-gear unit (hereinafter referred to as MGU) installed on the motor bogie of an electric train under operating conditions. Vibration measurement was carried out experimentally on a motor stand using vibration sensors of the SKF CMXA 80 type, installed on the casing of the traction gearbox and the frame of the traction motor. For measurements, a system was used that allows continuous recording of the vibration transducer signal over eight channels. Experimental data on the parameters of vibrations that occur on the bearing shield of the output shaft of the MGU were obtained by simulating the departure of a motor bogie by instantaneous load shedding. A pattern has been established that the vibration level under skid conditions in three coordinates X, Y, Z has sharp bursts of activity. During the MGU operation in the traction mode, it was found that a sharp increase in the amplitude of harmonics with frequencies that are multiples of the gear frequency is associated with the coincidence with the natural frequency of the MGU case. When switching to the coast down mode in the frequency range of about 1.5 kHz, a random vibration is recorded on the MGU body, the RMS acceleration value of which exceeds 50 $\boldsymbol{\mathrm{m}/\mathrm{s}^{2}}$, which is comparable to the acceleration value when passing the skid.

Determination of the Strength Characteristics of Traction Gears Under Shock Loads

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