Contactless energy transfer for main-line rail vehicles

In the context of an increasing importance of electric mobility with the aim to reduce greenhouse gas and noise emissions, railway operators intensify efforts to replace diesel vehicles with locally emission-free electric traction. Therefore more and more tracks need to be electrified. These electrified lines are the primary object of this paper. In 2010, the total electrified track length worldwide amounted to 262,000 km. For main-line electric rail vehicles the power is almost exclusively transmitted through a sliding contact between roof-mounted pantographs and overhead catenary systems. In main-line railway networks both alternating current as well as direct current is applied. Direct current systems (DC systems) hold a share of about 37 % of electrified railways worldwide. However, due to the comparatively low level of nominal voltages of not more than 3 kV, one has to consider that DC systems are inappropriate for high performance main-line operation and especially in high-speed applications. For alternating current systems (AC systems) frequencies of either 16.7 Hz or 50 Hz are applied. Worldwide AC systems using 50 Hz at a nominal voltage of 25 kV are predominant. The global share of 25 kV AC systems is approximately 46 % of the electrified railway networks.