Design and simulation of a high power quality regenerative PWM rectifier system for 1 MW electric locomotives

This paper presents the design and simulation of a high power quality regenerative PWM rectifier system for electric locomotives rated at 1 MW. The demand for efficient use of energy sources and high power quality requirements mandate the use of PWM rectifiers when interfacing the traction converters to the railway power system. The paper first develops the simulation models of the converter power stage and the controller. Then, a design procedure, which determines the critical design parameters, is presented. In addition, a controller that achieves unity power factor and a sinusoidal current that has a total harmonic distortion (THD) less than 2% at the worst case without employing a passive filter is developed. The significant reduction in the switching frequency ripple and the harmonics that enables the filterless design is realized by the interleaved operation of the parallel-connected rectifier units. In conclusion, the concept and the proposed design are verified through simulation studies.