Characteristics of a two-phase double-superimposed auxiliary impulse commutated chopper

This paper deals with circuit configurations, operations, characteristics and evaluations of a two-phase auxiliary impulse commutated chopper derived from the McMurray inverter. The auxiliary impulse commutated chopper is composed of at least two main thyristors which alternately repeat turn-on and turn-off during each cycle operation. A commutating capacitor is commonly combined with the main thyristors to supply a commutating current for them in a reverse direction. A plurality of auxiliary thyristors is set for charging the capacitor in alternative polarities and selectively discharging through the main conducting thyristors. Since the first trial operation in 1968 of d. c. electric trains using the auxiliary impulse commutated chopper, this type chopper cannot be discarded for chopper electric trains.