Linear asynchronous traction drive in urban rail and maglev transport systems

Abstract

The development of transport infrastructure of large cities with high population density and development should be carried out on the basis of innovative technical solutions, that allow to simplify the conditions of laying of tracks, reduce the cost of construction, reduce noise, provide comfort to passengers and reduce the cost of operating rolling stock. One such solution, the effectiveness of which is confirmed by foreign experience, is the use of linear asynchronous traction drive (LATD) in urban rail and maglev transport systems. This, in particular, allows to increase the allowable value of slope paths to 6065, reduce the vertical dimensions of rolling stock to 3.15 m, reduce the diameter of the tunnel by 2530%. The release of the wheel pair from the function of the implementation of traction effort makes it possible to apply on the wagons the articulated semi-frames of trolleys, that ensures better rolling stock in curves, and as a result - less wear of wheels and rails and less noise.
 This article analyzes the advantages and disadvantages of LATD compared to the traction drive of traditional execution, considers variants of constructive performance of linear induction motors (LIM), processes of electromechanical energy conversion in LIM, the option of building a LATD control system is presented. The article examines the flat LIM, which have found use in the transport systems of major cities in Asia and America. The processes of energy conversion in LIM are distinguished by the presence of a longitudinal edge effect, which determines the distortion of the resulting magnetic field, which is manifested in the reduction of induction and the displacement of the peak of the induction distribution curve to the escaping edge of the inductor. This effect is particularly manifested in high-speed LIMs with high quality. When the linearity of the magnetic environment is allowed, the resulting electromagnetic force of the LIM can be considered as the sum of electromagnetic forces created by the main field, as well as the direct and reverse fields of the longitudinal edge effect. The edge effects reduce efficiency and power ratio of LIM. The article discusses ways to compensate for the edge effects, as well as an overview of the world experience of the use of LATD in rail and maglev transport systems.
 The advantages of LATD and the world experience of its use suggest that for urban transport systems at speeds of up to 100-120 km/h this drive can be a real competition to traditional urban rail systems.