Semiconductor power-switching apparatus

Claim 2

Apparatus for semiconductor switching of relatively highcurrent, high-voltage electrical power leads comprising: a triggerable semiconductor current-swtiching device having first and second main terminals and a gate terminal, conduction between the main terminals being initiated by applying a triggering current to the gate terminal and being sustainable by internal regenerative action to provide a latching mode of operation; a transistor having collector, emitter, and base terminals, the collector and emitter terminals being serially connected in a power circuit with the main terminals of the current-switching device, conduction between the collector and emitter terminals being a function of a current applied to the base terminal; means for applying a triggering current signal to said gate terminal; means, including an input terminal, for applying a control current signal to said base terminal thereby to initiate conduction through the serially connected device and transistor; and means providing a low-impedance shunt current path around the collector-emitter circuit of the transistor from the gate terminal of the current-switching device whereby when the control current signal is withdrawn from the base terminal to terminate conduction between the collector and emitter terminals, substantial current can momentarily flow from the gate terminal bypassing one of the main terminals thereby turning off the current-switching device.

Claim 3

Apparatus as set forth in claim 1 wherein said device is a silicon-controlled rectifier.

Claim 4

Apparatus as set forth in claim 1 wherein said low-impedance shunt path comprises a low-impedance input signal source.

Claim 5

Apparatus as set forth in claim 1 wherein said low-impedance shunt path comprises a diode.

Claim 6

Apparatus as set forth in claim 1 further comprising a second transistor wherein said low-impedance shunt path comprises the collector-emitter circuit of the second transistor.

Claim 7

Apparatus as set forth in claim 1 wherein said means for applying a triggering current signal to the gate terminal includes said input terminal.

Claim 8

Apparatus as set forth in claim 1 wherein said means for applying a triggering current signal includes a voltage supply circuit.

Claim 9

Apparatus as set forth in claim 1 which further includes a second input terminal adapted to be connected to a separate triggering signal source.

Claim 10

Apparatus as set forth in claim 1 wherein an impedance is interconnected between said gate and base terminals.

Claim 11

Apparatus as set forth in claim 9 wherein said impedance is a resistance.

Claim 12

Apparatus as set forth in claim 9 wherein said impedance includes a diode.

Claim 13

Apparatus as set forth in claim 1 wherein said means for applying controlled current signal to said base terminal includes a second transistor having collector, emitter and base terMinals, the collector-emitter circuit of said second transistor being included in the low-impedance shunt current path, the base terminal of said second transistor comprising said input terminal, conduction between the collector and emitter terminals of the second transistor thereby being a function of the input signal.

Claim 14

Apparatus as set forth in claim 12 wherein said means for applying a triggering current signal to said gate terminal comprises a voltage supply circuit for supplying the second transistor with operating voltage.

Claim 15

Apparatus as set forth in claim 1 wherein said means providing a low-impedance shunt current path includes a diode connected between the gate terminal of said current-switching device and the emitter terminal of said transistor.

Claim 16

Apparatus as set forth in claim 14 wherein said means for applying a triggering control signal to said gate terminal comprises a diode connected between the gate terminal and the input terminal and said means for applying a control current signal to said base terminal comprises a resistance connected between the base terminal and the input terminal.

Claim 17

Apparatus for semiconductor switching of relatively high-current, high-voltage electric power loads comprising: a triggerable semiconductor current-switching device having first and second main terminals and a gate terminal, conduction between the main terminals being initiated by applying a triggering current to the base terminal and being sustainable by internal regenerative action to provide a latching mode of operation; a transistor having collector, emitter and base terminals, the collector and emitter terminals being serially connected in a power circuit with the main terminals of the current-switching device, conduction between the collector and emitter terminals being a function of a current applied to the base terminal; circuit means, including an input terminal, connected to said gate terminal for applying a triggering current signal thereto; second circuit means, including a second input terminal, connected to said base terminal for applying a control current signal thereto; and diode means, connected between said gate terminal and the emitter terminal of said transistor, for providing a low-impedance shunt current path around the collector-emitter circuit of the transistor from said gate terminal whereby when the control current signal is withdrawn from the base terminal to terminate conduction between the collector and emitter terminals, substantial current can momentarily flow from said gate terminal bypassing one of the main terminals thereby turning off the current-switching device.

Claim 18

Apparatus for semiconductor switching of relatively high-current, high-voltage electric power loads comprising: a triggerable semiconductor current-switching device having first and second main terminals and a gate terminal, conduction between the main terminals being initiated by applying a triggering current to the base terminal and being sustainable by internal regenerative action to provide a latching mode of operation; a transistor having collector, emitter and base terminals, the collector and emitter terminals being serially connected in a power circuit with the main terminals of the current-switching device, conduction between the collector and emitter terminals being a function of a current applied to the base terminal; circuit means, including an input terminal, connected to said gate terminal for applying a triggering current signal thereto; second circuit means, including a second input terminal, connected to said base terminal for applying a control current signal thereto; and diode means, connected between said gate terminal and the emitter terminal of said transistor, for providing a low-impedance shunt current path around the collector-emitter circuit of the transistor from said gate terminal whereby when the control current signal is withdrawn from the base terminal to terminate conduction between the collector and emitter terminals, substantial current can momentarily flow from said gate terminal bypassing one of the main terminals thereby turning off the current-switching device.