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.

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.

Comparative research of electrical energy transformation processes in locomotive traction drives with asynchronous motors and series-wound brushed DC motors

An estimate of the Russian railways expenses level for the purchase of fuel and energy resources is given. It is shown the costs for the purchase of electric energy for train traction account for more than half of the total costs. In this regard, the problem of increasing the traction rolling stock energy efficiency seems certainly relevant. The diagram of voltage and current measurements at the primary winding of the AC cargo electric locomotive transformer is given. The experimental data processing algorithm is proposed. A comparative analysis of the results obtained for electric locomotives with series-wound brushed DC motors (throughout what follows will be denoted as BTMs) and asynchronous traction motors (will be denoted as ATMs) showed that the power factor of the asynchronous drive is higher: 0.99, compared to 0.65 for the drive with BTMs; and the coefficient of nonlinear current distortions is only 0.15, compared to 0.53 for the BTMs. The conclusion is made about higher efficiency of electric energy conversion process in asynchronous traction drive in trust mode.

Simulation of drive power in mechatronic systems

The results of research on determining the parameters and circuit solutions of traction drives of funicular cars are presented in this paper. As a result of the research, it has been revealed that the funiculars, the bodies of which have an articulated joint, possess the greatest advantages. It is effectually to use three-phase AC machines with permanent magnets as traction electric motors. The mechanical part of the drive must contain a speed transformer with a gear rack-wheel type gearing. The wheels of the running gears perform the function of holding the car on the track structure. The traction force is performed in a gearing, the rack of which is placed between the rails of the track structure. The given method for calculating the power of the drive motor made it possible without question to determine its dependence on the angle of inclination of the railroad bed.

Analysis and Experimental Verification of the Demagnetization Vulnerability in Various PM Synchronous Machine Configurations for an EV Application

Safety is a critical feature for all passenger vehicles, making fail–safe operation of the traction drive system highly important. Increasing demands for traction drives that can operate in challenging environments over wide constant power speed ranges expose permanent magnet (PM) machines to conditions that can cause irreversible demagnetization of rotor magnets. In this paper, a comprehensive analysis of the demagnetization vulnerability in PM machines for an electric vehicle (EV) application is presented. The first half of the paper presents rotor demagnetization characteristics of several different PM machines to investigate the impact of different design configurations on demagnetization and to identify promising machine geometries that have higher demagnetization resistance. Experimental verification results of rotor demagnetization in an interior PM (IPM) machine are presented in the latter half of the paper. The experimental tests were carried out on a specially designed locked-rotor test setup combined with closed-loop magnet temperature control. Experimental results confirm that both local and global demagnetization damage can be accurately predicted by time-stepped finite element (FE) analysis.

Study of the Thermal Conductivity of Soft Magnetic Materials in Electric Traction Machines

The power density of traction drives can be increased with advanced cooling systems or reduced losses. In induction machines with housing and shaft cooling, the produced heat in the stator and rotor winding system needs to be extracted over the rotor and stator lamination. The influence of soft magnetic material parameters, such as texture, thickness or alloy components on the magnetization and loss behavior, are well studied. Studies about influencing factors on the thermal conductivity are hard to find. Within this study, eight different soft magnetic materials are analyzed. An analytical approach is introduced to calculate the thermal conductivity. Temperature-dependent measurements of the electric resistivity are performed to obtain sufficient data for the analytical approach. An experimental approach is performed. The thermal diffusivity, density, and specific heat capacity are determined. An accuracy study of all measurements is performed. The analytical and the experimental approach show good agreement for all materials, except very thin specimens. The estimated measurement error of those specimens has high values. The simplified case study illustrates the significant influence of the different soft magnetic materials on the capability to extract the heat in the given application.