Line filter for high power inverter locomotive using active circuit for harmonic reduction

One of the most heavy electrical parts in a high power and high performance 3 kV locomotive is the passive input filter that has to reduce the harmonic contents of overhead line current according to the EMC with the signalling system. The authors explain how it is possible to reduce input filter weight and dimension using a combination of passive and active parts for a 3 kV, 6 MW inverter locomotive for Italian Railways. A special active filter topology is designed to combine high voltage operation of the 3 kV passive filter and low voltage of the high frequency IGBT PWM inverter included in the active one. Control techniques are explained and simulation results are shown