Control of Traction Rail Vehicle with Free-wheels

This paper is focused on the low-floor trams with free-wheels driven by PMSM motors, especially on their traction control system. The first part describes modern low-floor trams, particularly the type 15T produced by Škoda Transportation. The second part of the paper presents the simulations of characteristics operati ng such tram in the rail and the results of these simulat ions. The last part of the paper describes the mechanical con struction and electrical equipment of a light experimental rail car, that will be used as an experimental base for a imp rovement of the control system for the tram 15T. Keywords—low-floor tram, free-wheel drive, gearless dr ive, PMSM, control system, experimental vehicle. I. MODERN LOW-FLOOR TRAMS Tram vehicles have some specific elements in comparison with standard rail vehicles. Streetcar t r cks are led through the streets of urban development, o ften not separated from car traffic, characterized by the pr esence of curves of very small radius (up to 20 m) and steep inclines. Challenging tracing of tramlines makes th e construction of tram vehicles quite difficult. In a ddition to further tram improving it is now required a low-fl oor vehicle, which further increases the difficulty of the structural design of these vehicles and forces some th r specifics. The use of low-floor vehicles in the pub lic transport system allows not only convenient trave l for citizens with limited mobility or passengers with w heel chairs but also significantly speeds up the exchang e of passengers at tram stops. The first low-floor tram vehicles began to be produ ced in the second half of the 80’ of the 20th century. Since then, there was designed a large number of low-floo r trams of different solutions to achieve the highest proportion of low-floor space. A high ground is considered to be a floor mounted at a height of abo ut 600 to 900 mm above the rail, a low floor is then at a height of about 350-450 mm above the rail. The low-floor veh icles are divided into two categories semi low floor an d fully low floor. Typical arrangement of low-floor trams a re illustrated in Fig. 1 and 2. The proportion of the low floor with semi low-floor trams ranging from about 15% (F ig. 1 top) to 75% (Fig. 1 below), in the case of a fully low-floor vehicles, the low floor is located along the passen ger lounge. Fig. 1 Partially low-floor tram Fig. 2 Fully low-floor tram Location of low-floor trams bogies requires the use of special bogies. For the partially low-floor tram th ere are often used normal (non-driven) bogies and as a driv e standard chassis located above the floor in a stand ard height. For full low-floor trams all the bogies, i ncluding drive, are then low-rise. A common feature of almost all types of low-floor bogies is the use of independently rotating wheels instead of conventional wheel sets. In case of drive bogie, th se ‘axles’ are driven by a pair of longitudinally stor ed motors with double-sided output or each wheel is independe ntly driven by one motor. Behavior of independently rotating wheels moving in a dorm is different from that of conventional wheel s ts. While the wheel set is used from the very beginning of rolling stock and therefore the behavior in rail i s well known, independently rotating wheels on rail vehicl es is relatively new element that needs to be continually examined in detail. Using independently rotating wheels in bogies of tr ams was elicited from the low-platform. However, it ca n lso be used for other important improvements of vehicle s in the case of independently rotating wheels when eac h of them is driven by its own motor it is possible to control each motor to improve road holding, in particular to reduce wear on wheels and rails and increase vehicl e safety against derailment. Transactions on Electrical Engineering, Vol. 1 (201 ), No. 4 112