Abstract :
Power factor and harmonics are increasingly important issues for railway authorities. This paper presents a comparison by digital computer simulation of the power factor and harmonic performance of four power converter circuits, under various supply and load conditions. Of these circuits, the pulse converter is shown to require a relatively small power filter while delivering almost unity power factor across the load and supply variation ranges. These advantages and its inherent regenerative capability have led to it superseding today´s most common traction converter topology, half controlled converters (HCCs) with tuned filters in the world´s latest high-technology rolling stock. The performance of the HCCs is shown, however, to be a viable low-technology option. The paper also contains results of detailed analytical and simulation based investigations of the three level pulse converter, which show that it is an appropriate topology for implementing a harmonic optimised PWM strategy, producing only 50% of the psophometric current of an equivalent natural sampled PWM strategy.
