Recent power electronic applications in propulsion systems for electric multiple units

In the past ten years there have been major changes in the semiconductor devices available to traction equipment designers. The availability of new power semiconductor devices such as gate turn-off (GTO) thyristors and, more recently, insulated gate bipolar transistors (IGBT), coupled with acceptance of microprocessor-based control systems by railway operators has led to rapid introduction of fleets of cost-effective chopper and three-phase inverter propulsion systems. This paper presents examples and benefits of such modern systems.