Introduction to special issue on high-efficiency and intelligent train traction system

The development of train technology is mainly reflected in the development of the traction system. The train traction system includes several key pieces of equipment, such as the pantograph, traction transformer, traction converter and traction motor. It determines the performance of train start, acceleration, constant speed operation and braking. The traction system has the characteristics of complex composition and extreme high faults ratio. It can easily lead to speed limit and delay. Timely fault diagnosis, fault early warning and maintenance are of great significance to ensure the normal operation of the train. In addition, cooling is another key technology to ensure the healthy operation of the traction system, which requires high efficiency, small volume, easy maintenance and less environmental pollution. In recent years, with the increasingly prominent world energy problems, it results in a demand for trains to be more energy-saving, more efficient and more intelligent. The power consumption of the traction system accounts for the highest proportion in the power consumption of train operation system. Therefore, efficient control and operation of the traction system are in urgent demand for the energy-saving operation of trains.

Centring on the high-efficiency and intelligent train traction system, this special issue covers papers focusing on diagnosis and maintenance technology of the traction system, scheduling management of the urban rail transit power supply, motor control and the heat conduction problems of key devices.

Among them, an detailed review by Jisheng Dai, Rongjun Ding, Zhaoyi Guan and Shaolong Xu [1] describes the main fault modes of transmission machinery, systematically summarizing and comparing the advantages and disadvantages of the existing diagnostic methods, which provides a reference for the future research related to fault diagnosis on transmission machinery of the traction system.

Fault diagnosis of the traction system is an important branch of maintenance technology. Shaolong Xu, Chunyang Chen, Zhenjun Lin, Xiao Zhang, Jisheng Dai and Liangjie Liu [2] discuss condition-based maintenance and key technologies of the traction electrical system in major countries of the world, pointing out the direction for the research and the development of traction maintenance technology.

In order to verify the train design, power supply system and dispatching management of urban rail transit more efficiently, Yu Zhang, Zhaoyang Zhang, Li'en Xu, Ting Ying, Jianghong Li, Huaguo Chen, Yunqing Hu and Guangdong Qing [3] establish a hybrid real-time simulation system composed of train hardware-in-the-loop simulation, power supply system numerical simulation and line environment numerical simulation. Further, the reliability of the simulation system is verified by experiments.

Yuliang Wen, Hanfeng Zheng, Fang Yang and Xiaofan Zeng [4] propose an indirect stator-flux control method for a permanent magnet synchronous motor, which effectively overcomes the difficulties in solving the load angle corresponding to current and torque, realizing maximum torque per ampere control and flux-weakening control in a high-efficiency permanent magnet synchronous motor control.

Yang Zeng [5] extends the machine learning method to the boundary condition identification problem of heat conduction and proposes an auto-encoder-based approximate Bayesian computation method. The feasibility and flexibility of this proposed method are demonstrated with the numerical cases.

Hui Wu, Gang Zhang, Zhaozan Feng, Kai He, Lei Yao, Wei Li and Shichune Yao [6] carry out an experimental investigation on pumped two-phase cold plate of Insulated Gate Bipolar Transistor (IGBT) used in HXD1C locomotives, and develop a numerical simulation model for saturated flow boiling. The performance of pumped two-phase cold plate of IGBT could be further improved with the aid of the model.

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