초록 ▼

Apparatus for providing firing signals to a phase controlled rectifier circuit at a time at which valves in the rectifier circuit are forward biased without the need for providing continuous firing signals. The apparatus monitors the voltage applied across the rectifier valves and provides a signal

Apparatus for providing firing signals to a phase controlled rectifier circuit at a time at which valves in the rectifier circuit are forward biased without the need for providing continuous firing signals. The apparatus monitors the voltage applied across the rectifier valves and provides a signal when a valve is forward biased. This signal is applid to a gating circuit which determines whether a normal phase control firing command was initiated prior to the time the valve became forward biased. If such a command was initiated, the gating circuit passes the signal to a valve firing circuit which provides firing signals to the rectifier circuit. If the firing command was not previously initiated, the signal is inhibited and firing signals are subsequently applied to the rectifier circuit upon receipt of a firing command.

대표청구항 ▼

A power control system for an electric motor powered from an alternating voltage source comprising: (a) a phase-controlled rectifier circuit having a-c input terminals adapted to be connected to the alternating voltage source, a pair of d-c output terminals, and means including a plurality of contro

A power control system for an electric motor powered from an alternating voltage source comprising: (a) a phase-controlled rectifier circuit having a-c input terminals adapted to be connected to the alternating voltage source, a pair of d-c output terminals, and means including a plurality of controllable electric valves for interconnecting the input and output terminals, said valves being cyclically fired at firing angles that can be varied to control the average magnitude of d-c voltage across said output terminals; (b) a filter circuit including a shunt capacitor connected to said d-c terminals; (c) power regulating means for connecting said filter circuit to the motor and operative to control the motor power as desired; and (d) control means for periodically supplying firing signals to said rectifier circuit so as to fire said valves at variable firing angles, said control means including: (i) first means for generating a train of first firing signals in synchronism with the alternating voltage at said input terminals, said first means including means responsive to the d-c voltage across said capacitor for varying the firing angles of said first firing signals as necessary to maintain substantially a desired magnitude of capacitor voltage; (ii) second means responsive both to said capacitor voltage and to the alternating voltage at said input terminals for generating second firing signals every time the instantaneous magnitude of the latter voltage becomes greater than the actual magnitude of capacitor voltage; and (iii) means for coupling to said rectifier circuit said first firing signals and additionally any second firing signal that is generated after a first firing signal during each half cycle of alternating voltage.