Thyristor gating and phase shift circuit

Claim 2

A phase control gating circuit for developing a pulse output in time relation to a cyclical power source comprising a charging circuit in operative shunt connection with said source of power for developing a gating potential, a pulse forming circuit including controlled switching means and a load impedance in operative shunt connection with said source of power for developing an output pulse across said load impedance upon actuation of said controlled switching means, the latter including a control electrode for actuating said controlled switching means in response to a trigger pulse, and a voltage responsive trigger element in operative connection with said control elecTrode and said charging circuit for developing such trigger pulse in each cycle of said power source when the potential in said charging circuit attains a predetermined level.

Claim 3

A circuit as set forth in claim 1 wherein said charging circuit comprises a capacitor and a variable impedance in connection therewith for varying the charging rate of said capacitor to adjust the time of development of the gating potential thereacross.

Claim 4

A circuit as set forth in claim 2 wherein said variable impedance is an adjustable resistor in series circuit connection with said capacitor.

Claim 5

A circuit as set forth in claim 1 wherein said controlled switching means comprises complementary transistors in parallel base and emitter connection and said voltage responsive trigger element is a silicon bilateral switch for developing trigger signals on each half cycle of said power source for full wave phase control.

Claim 6

A circuit as set forth in claim 1 further including means operatively connected with said charging circuit for discharging same in each cycle of said power source, said discharging means being responsive to initial current flow in said charging circuit and comprising a pair of control elements and a pair of current directing devices interconnected therewith for establishment of bidirectional current discharge paths.

Claim 7

A circuit as set forth in claim 5 wherein said pair of control elements comprise complementary transistors in parallel base and emitter connection and said pair of current directing means comprises diodes respectively connected to the collector electrodes of said transistors, said charging circuit including a capacitor therein in shunt connection with each said transistor and diode combination to establish current discharge through the collector-emitter paths of said transistors.

Claim 8

A circuit as set forth in claim 6 wherein said controlled switching means comprises complementary transistors in parallel base and emitter connection and said voltage responsive trigger element is a silicon bilateral switch for developing trigger signals on each half cycle of said power source, being operatively connected between the bases of said transistors and said capacitor.

Claim 9

Variable phase gating apparatus for thyristors and the like operative from a cyclical power source, comprising a pair of terminals adapted for receipt of voltage from said power source, a first circuit in connection with said terminals comprising first bidirectional switching means having a control electrode and a load impedance in series connection with said first switching means, a second circuit in connection with said terminals comprising a capacitor, current responsive switching means in connection with said capacitor for bidirectional discharge of said capacitor in response to reversal of current flow therethrough and means for controlling the charging rate of said capacitor, and a voltage responsive switching element in connection between said control electrode and said capacitor for energizing said bidirectional switching means to develop an output pulse in said load impedance when the voltage in said capacitor attains a predetermined level.

Claim 10

Variable phase gating apparatus for thyristors and the like operative from a cyclical power source, comprising a pair of terminals adapted for receipt of voltage from said power source, a first circuit in connection with said terminals comprising first bidirectional switching means having a control electrode and a load impedance in series connection with said first switching means, a second circuit in connection with said terminals comprising a capacitor, current responsive switching means in connection with said capacitor for bidirectional discharge of said capacitor in response to reversal of current flow therethrough and means for controlling the charging rate of said capacitor, and a voltage responsive switching element in connection between said control electrode and said capacitor for energizing said bidirectional switching means to develop an output pulse in said load impedance when the voltage in said capacitor attains a predetermined level.

Claim 11

Apparatus as set forth in claim 8 wherein said current responsive switching means comprises NPN and PNP transistors having base electrodes connected to one of said pair of terminals and emitter electrodes connected to said capacitor, and a diode in connection between said capacitor and each collector electrode of said transistors.

Claim 12

Apparatus as set forth in claim 9 wherein said bidirectional switching means comprises NPN and PNP transistors having base electrodes connected in common as said control electrode and emitter electrodes connected in common to said load impedance, the collector electrodes of said transistors being connected by way of diodes to a second capacitor in a charging circuit.

Claim 13

A bidirectional discharge circuit for a capacitor in a phase shift gating circuit and the like energized from an alternating source of pOwer and including means for controlling the charging rate of said capacitor, comprising NPN and PNP transistors having base electrodes connected in common and emitter electrodes connected in common, said emitter electrodes further being connected to one side of said capacitor to establish capacitor charging current circuits through one or the other of the base-emitter paths of said transistors dependent upon the polarity of said power source, a diode connected between each collector electrode of said transistors and the other side of said capacitor to establish capacitor discharge current circuits through one or the other of the collector-emitter paths of said transistors, said diodes being poled to isolate said transistors from reverse voltage, each said discharge circuit being operative in response to forward bias of the respective base-emitter path of said transistors due to charging current flow and potential occurring across said capacitor of a polarity to cause forward bias of the respective diode.

Claim 14

A bidirectional discharge circuit for a capacitor in a phase shift gating circuit and the like energized from an alternating source of pOwer and including means for controlling the charging rate of said capacitor, comprising NPN and PNP transistors having base electrodes connected in common and emitter electrodes connected in common, said emitter electrodes further being connected to one side of said capacitor to establish capacitor charging current circuits through one or the other of the base-emitter paths of said transistors dependent upon the polarity of said power source, a diode connected between each collector electrode of said transistors and the other side of said capacitor to establish capacitor discharge current circuits through one or the other of the collector-emitter paths of said transistors, said diodes being poled to isolate said transistors from reverse voltage, each said discharge circuit being operative in response to forward bias of the respective base-emitter path of said transistors due to charging current flow and potential occurring across said capacitor of a polarity to cause forward bias of the respective diode.

Claim 15

A circuit as set forth in claim 11 wherein one of said diodes has an anode connected to the collector of said PNP transistor and a cathode connected to said other side of said capacitor and the other of said diodes has a cathode connected to the collector of said NPN transistor and an anode connected to said other side of said capacitor.