To address the engineering challenge that induced voltage generated by electromagnetic coupling between AC OCS and DC urban rail power supply OCS during parallel laying poses threats to personnel safety and disturbs vehicle operation, this study focuses on the Lvshun test loop of Dalian Locomotive, where a 5 m spacing between AC/DC lines hinders synchronous factory testing of rolling stocks. Mechanism modeling and suppression technology research were conducted. An equivalent circuit model was established, and a simulation platform based on MATLAB/Simulink was built and calibrated with field data. The attenuation law of induced voltage with varying line spacing and transient characteristics under special conditions were revealed. Based on simulation results, an LC/LRC filtering suppression scheme was designed and verified through engineering implementation. By installing 3 groups of LRC filters and 1 group of LC filters on the test loop, the induced voltage was effectively suppressed to a safe range, resolving the bottleneck of synchronous multi-type vehicle testing and significantly improving production efficiency. This research provides important theoretical basis and engineering reference for AC/DC line planning and electromagnetic compatibility management in the context of integration of high-speed rail, inter-city rail, suburban railway and metro.
To address the problems that the current online condition monitoring of in-service motors cannot fully and accurately understand the equipment status due to narrow monitoring range, single data type and limited sensor layout, this paper proposes a model order reduction method for multi-physics coupling of motors based on artificial intelligence methods to achieve real-time simulation calculation of multi-physics of electric, magnetic, thermal and force fields for traction motors. Moreover, the digital twin model established based on the reduced-order model can realize real-time multi-physics condition monitoring for in-service motors. The results of the research show that the reduced-order model not only has a simulation calculation accuracy of not less than 90%, but also improves the multi-physics simulation calculation efficiency by up to 5 orders of magnitude, showing a certain engineering application value of the model in the direction of motor operation and maintenance.
To address the demagnetization issues of permanent magnet materials under operational conditions, this paper investigates the magnetic property aging law of samarium-cobalt (Sm2Co17) magnets under high temperature, vibration, thermal shock, and high-temperature coupled demagnetizing fields. The Sm2Co17 magnets exhibit the following properties at 200 ℃: Br=1.048 T, Hcb=781.6 kA/m, Hcj=1 465.0 kA/m, and (BH)max=207.7 kJ/m3, and their demagnetization curves (B curves) show no knee point. After aging treatment at 200 ℃ with Pc=2.16, the flux loss was only 0.4%, confirming the Sm2Co17 magnet's stable performance at 200 ℃. Under thermal shock and vibration conditions, the flux loss was less than 0.75% and 0.41% respectively, verifying the magnet's stability under thermal shock and vibration. Under high temperature or coupled high temperature and demagnetizing field conditions, significant irreversible demagnetization occurred during the initial 6 hours, after which the flux loss stabilized. Therefore, to ensure the stability of permanent magnets, pre-stabilization magnetization treatment can be performed based on motor operating temperatures to meet the high stability requirements for permanent magnets in complex motor conditions.
To investigate potential fault prediction methods for variable frequency motors, this paper takes a traction motor driven by a two-level frequency converter as the research object, and studies the influence rule of different insulation resistance values and fault locations on the phase-to-ground voltage and neutral-point-to-ground voltage through a combination of simulation analysis and test. The results are as follows: the critical insulation resistance value at which the phase-to-ground voltage starts to distort depends on the ground capacitance and converter frequency of the motor windings; when the fault point is located at the starting coil, the difference in oscillation characteristics between the phase-to-ground voltage waveform of the faulty phase and that of the other two phases is the most pronounced, at which the neutral-point-to-ground peak voltage increases by about 60% compared to the normal value. As the fault point approaches the neutral point, the three-phase-to-ground voltage waveforms become more similar, and the distorted peak value of the neutral-point voltage gradually approaches the normal peak voltage. The above rule provides a theoretical basis for voltage feature extraction and early prediction of insulation faults in variable frequency motors.
Current diesel-hydraulic/hydrodynamic drive systems for tamping and stabilizing vehicles suffer from high energy consumption, lagging torque response, low working efficiency, and inconvenient maintenance. This paper addresses these issues in the context of the DWL-32 continuous dual-sleeper tamping and stabilizing vehicle. It proposes a permanent magnet electric drive system solution that innovatively introduces electric traction technology to achieve integrated high- and low-speed traction of the complete vehicle and high-precision working at constant low speeds. Firstly, requirements for various working conditions were decomposed and quantified, and further calculations were conducted to derive traction/braking characteristics. Secondly, based on the traction and running characteristics, an electric drive system topology was built using permanent magnet electric drive technology, followed by the calculation and analysis for the electric drive system and the design of key components. Thirdly, for high-precision working at constant low speeds, the permanent magnet traction motor design was optimized, and the converter drive control mode was selected. Finally, key component prototypes developed for the electric drive system were tested on the bench and complete vehicle tests were carried out. Bench test results show that the electric drive system meets the temperature rise requirements during high-speed towing. Complete vehicle test results show that the designed electric drive system is rationally structured and delivers reliable performance that meets the requirements in complete vehicle traction as well as working and running conditions and achieves efficient response to control requirements at constant low speeds. Compared with the traditional technology route of hydraulic/hydrodynamic drive, the proposed solution improves working efficiency by 15%, providing strong support for the electrification upgrade and transformation of new-generation large-scale track maintenance machinery.
