Direct current power control system

Claim 2

A direct current power control system comprising, in combination, a. a source of direct current, b. a load, c. a plurality of main thyristors connected in parallel circuit relationship in an electric path connecting said source to said load, and controlled in conduction in a predetermined phase relationship to be operative in their conducting state to supply the load current from said source to said load therethrough; d. one pulse distribution thyristor connected to each of said main thyristors, e. a common pulse generator unit for generating a commutation pulse, said pulse generator unit being connected across said plurality of main thyristors through said pulse distribution thyristors to supply a commutation pulse to a selected one of said main thyristors through the associated distribution thyristor, and f. said pulse generator unit including a commutation capacitor, a voltage inverter disposed in parallel circuit relationship with respect to said capacitor to invert the polarity of a voltage charged on said capacitor, and a commutation reactor connected in series circuit relationship with at least one of said capacitor and thyristor.

Claim 3

A direct current power control system as claimed in claim 1 wherein said pulse distribution thyristors are successively fired at predetermined fixed time points while each of said main thyristors is variable in its firing time point with respect to said predetermined fixed time point of the associated distribution thyristor.

Claim 4

A direct current power control system as claimed in claim 1 wherein for each of said main thyristor, there are provided one smoothing reactor connecteD at one end to the cathode electrode of the main thyristor and at the other end to said load, and one semiconductor flywheel diode connected at one end to said cathode of the main thyristor and at the other end to said load.

Claim 5

A direct current power control system as claimed in claim 1 wherein said pulse generator unit includes a series combination of said commutation capacitor and said commutation reactor, and a voltage inversion thyristor connected across said series combination of capacitor and reactor, said voltage inversion thyristor including an anode electrode connected to the positive terminal of said source, and a cathode electrode connected in common to the anode electrodes of said pulse distribution thyristors.

Claim 6

A direct current power control system as claimed in claim 1 wherein said pulse generator unit includes a series combination of a voltage inversion thyristor and said commutation reactor, and said commutation capacitor connected across said series combination of thyristor and reactor, said commutation capacitor being connected at one end to the positive terminal of said source and at the other end to the anode electrodes of said pulse distribution thyristors.

Claim 7

A direct current power control system as claimed in claim 1 wherein said pulse generator unit includes said commutation capacitor, said voltage inverter disposed in parallel circuit relationship with respect to said capacitor to invert the polarity of a voltage charged on said capacitor, and said commutation reactor connected in series circuit relationship to at least one of said capacitor and thyristor and a re-charging circuit for increasing the recharging rate of said commutation capacitor.

Claim 8

A direct current power control system as claimed in claim 1 wherein said pulse generator unit includes at least said commutation capacitor, a voltage inversion thyristor disposed in parallel circuit relationship with respect to said capacitor to invert the polarity of a voltage charged on said commutation capacitor, said commutation reactor connected in series circuit relationship to either one of said capacitor and thyristor, and a recharging circuit including a series combination of a semiconductor diode and a reactor connected across said voltage inversion thyristor to increase the recharging rate of said commutation capacitor.

Claim 9

A direct current power control system as claimed in claim 1 wherein said pulse generator unit includes at least said commutation capacitor, a voltage inversion thyristor disposed in parallel circuit relationship with respect to said capacitor to invert the polarity of a voltage charged on said commutation capacitor, said commutation reactor connected in series circuit relationship to either one of said capacitor and thyristor, and a recharging circuit including a series combination of a thyristor and a reactor disposed in parallel circuit relationship with respect to said commutation capacitor to increase the recharging rate of said commutation capacitor.

Claim 10

A direct current power control system as claimed in claim 1 wherein said pulse generator unit comprises said commutation capacitor, said commutation reactor, a voltage inversion thyristor serially connected to said commutation reactor to invert the polarity of a voltage charged on said commutation capacitor, and a recharging circuit including a semiconductor diode connected in parallel circuit relationship to said voltage inversion thyristor with said diode opposite in polarity to said thyristor.

Claim 11

A direct current power control system comprising in combination a. a direct current source having positive and negative terminals, b. a load having one terminal connected to the negative terminal of said source, c. a plurality of main thyristors each having an anode connected to the positive terminal of said source, d. a corresponding plurality of smoothing reactors each connected in series between the cathode of a respective main thyristor and the opposite terminal of said load, e. a corresponding plurality of flywheel diodes connected in series between the cathode of a respective main thyristor and the negative terminal of said source, f. a pulse generator unit having an output terminal and comprising a commutation capacitor connected between the positive terminal of said source and said output terminal, a thyristor connected in parallel with said capacitor with its anode connected to said positive terminal of said source and its cathode connected to said output and a commutation reactor connected in series with at least one said thyristor and said capacitor, and g. a corresponding plurality of pulse distribution thyristors each having an anode connected to said output of said pulse generator unit and a cathode connected to the cathode of a respective main thyristor.

Claim 12

A direct current power control system comprising in combination a. a direct current source having positive and negative terminals, b. a load having one terminal connected to the negative terminal of said source, c. a plurality of main thyristors each having an anode connected to the positive terminal of said source, d. a corresponding plurality of smoothing reactors each connected in series between the cathode of a respective main thyristor and the opposite terminal of said load, e. a corresponding plurality of flywheel diodes connected in series between the cathode of a respective main thyristor and the negative terminal of said source, f. a pulse generator unit having an output terminal and comprising a commutation capacitor connected between the positive terminal of said source and said output terminal, a thyristor connected in parallel with said capacitor with its anode connected to said positive terminal of said source and its cathode connected to said output and a commutation reactor connected in series with at least one said thyristor and said capacitor, and g. a corresponding plurality of pulse distribution thyristors each having an anode connected to said output of said pulse generator unit and a cathode connected to the cathode of a respective main thyristor.

Claim 13

A direct current power control system as claimed in claim 10, wherein said pulse distribution thyristors are successively fired at predetermined fixed time points while each of said main thyristors is variable in its firing time point with respect to said predetermined fixed time point of the associated distribution thyristor.