Railway traction power supply from the state of the art to future trends

In this paper, the authors show how high power static converters contribute to the voltage quality in railways. The first part of the paper gives an overview of power electronics solutions currently used by French National Railways and Swiss Federal Railways such as frequency converter for 15 kV/16.7 Hz system and line voltage booster or unbalance compensator for 25 kV/50 Hz system. Operating results for such devices are presented. The second part of the paper is dedicated to future trends in railway power supply. Innovative solutions concerning DC or AC systems are proposed. In each case, prototypes and experimental results are presented.