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A world’s advanced asynchronous traction system project program, jointly developed by Yongji Motor Factory of the China Railway Rolling stock Corporation (CRRC) and Xi’an Metro, has recently passed the review of 11 academicians and experts.

Traction systems are regarded as the "heart" of rolling stock, which provide both power and braking force for the vehicles. The technology had long been monopolized by foreign companies. 

Gui Weihua, an academician of the Chinese Academy of Engineering, said that foreign technologies are kept confidential to us. So China must develop its own system. The implementation of this project will realize the total localization of the core technology of metro vehicles' traction systems. 

It is worth mentioning that the system adopts the speed sensor-less control technology, which is cutting-edge internationally. Currently, the traction system has been successfully tested via a low-power simulator stand in laboratory and hopefully will go into full production in the next year, replacing the foreign systems currently being used on Lines 1 and 2 of the Xi'an Metro.