Thyristor state sensor

Claim 2

Means for monitoring the state of a periodically conducting electric valve adapted to be serially connected in an electric power circuit between a load and an alternating voltage system and arranged to be cyclically switched from a blocking state to a forward current conducting state in response to gate pulses generated by associated control means, comprising: a. voltage detecting means connected across said valve for comparing a signal proportional to the instantaneous magnitude of voltage across the valve with a predetermined reference signal representative of a threshold voltage level which is higher than the voltage drop across the valve when conducting and for emitting a signal indicating whether or nor said instantaneous magnitude exceeds said threshold level; and b. logic means responsive to said indicating signal for producing a predetermined output signal so long as said valve is in a conducting stage, said logic means including means coupled to said associated control means and responsive to the generation of said gate pulses for preventing the production of said predetermined output signal when the valve is in its blocking state and the instantaneous magnitude of voltage thereacross does not exceed said threshold level.

Claim 3

The monitoring means of claim 1 in which said logic means includes means for delaying the termination of said output signal for a predetermined interval of time at the conclusion of each conducting period.

Claim 4

Means for monitoring the state of a periodically conducting electric valve adapted to be serially connected in an electric power circuit between a load and an alternating voltage system and arranged to be cyclically switched from a blocking state to a forward current conducting state in response to gate pulses generated by associated control means, comprising: a. voltage detecting means comprising first means connected across said valve for comparing a signal proportional to the instantaneous magnitude of voltage across the valve with a predetermined reference signal representative of a threshold voltage level which is higher than the voltage drop across the valve when conducting, said first means being operative to provide a first signal whenever said instantaneous magnitude exceeds said threshold level, second means for providing a continuously available control voltage, third means for emitting a signal indicating that said instantaneous magnitude exceeds said threshold level, said indicating signal being electrically insulated from said first signal and from said control voltage, and fourth means connected between said second and third means and controlled by said first signal for causing said control voltage to energize said third means; and b. logic means coupled to both said voltage detecting means and said associated control means and responsive to said indicating signal and to the generation of said gate pulses for producing a predetermined output signal so long as said valve is in its conducting state.

Claim 5

Means for monitoring the state of a periodically conducting electric valve adapted to be serially connected in an electric power circuit between a load and an alternating voltage system and arranged to be cyclically switched from a blocking state to a forward current conducting state in response to gate pulses generated by associated control means, comprising: a. voltage detecting means comprising first means connected across said valve for comparing a signal proportional to the instantaneous magnitude of voltage across the valve with a predetermined reference signal representative of a threshold voltage level which is higher than the voltage drop across the valve when conducting, said first means being operative to provide a first signal whenever said instantaneous magnitude exceeds said threshold level, second means for providing a continuously available control voltage, third means for emitting a signal indicating that said instantaneous magnitude exceeds said threshold level, said indicating signal being electrically insulated from said first signal and from said control voltage, and fourth means connected between said second and third means and controlled by said first signal for causing said control voltage to energize said third means; and b. logic means coupled to both said voltage detecting means and said associated control means and responsive to said indicating signal and to the generation of said gate pulses for producing a predetermined output signal so long as said valve is in its conducting state.

Claim 6

The monitoring means of claim 1 in which said fourth means causes said control voltage to energize said third means on operation Of said first means, and in which said logic means produces said output signal in response to the absence of said indicating signal and, concurrently, either the generation of a gate pulse or the presence of said output signal.

Claim 7

The monitoring means of claim 3 in which said second means comprises: a. energy storage means, b. charging means coupled to said valve for supplying said energy storage means with energy derived from the electric power circuit, and c. means for isolating said first means from said energy storage means.

Claim 8

The monitoring means of claim 3 in which said second means comprises a capacitor connected by means of a charging circuit across said valve so as to be charged

Claim 9

Means for monitoring the state of a periodically conducting electric valve having a pair of main electrodes adapted to be serially connected in an electric power circuit including a load and one phase of a polyphase alternating voltage source and being arranged to be cyclically switched from a blocking state to a conducting state in response to gate pulses generated by associated control means, comprising: a. level detecting means connected across said main electrodes of the valve and operative to provide a first signal only when the instantaneous magnitude of voltage across the valve exceeds a predetermined threshold level which is higher than the voltage drop across the valve when conducting; b. means for deriving a control voltage from said source, said control voltage deriving means including a capacitor coupled to all phases of the source and arranged to be charged therefrom while the instantaneous magnitude of source voltage is higher than an amount equivalent to the magnitude of said control voltage and to sustain said control voltage during any interval when the instantaneous magnitude of source voltage is lower than said amount; c. means for emitting an indicating signal when energized by said control voltage; d. switching means connected between said signal emitting means and capacitor and controlled by said first signal for causing said control voltage to energize said emitting means; and e. logic means having one input for receiving said indicating signal and having a second input responsive to the generation of said gate pulses, said logic means being dependent upon the contemporaneous states of both inputs for producing a predetermined output signal so long as said valve is in its conducting state.

Claim 10

Means for monitoring the state of a periodically conducting electric valve having a pair of main electrodes adapted to be serially connected in an electric power circuit including a load and one phase of a polyphase alternating voltage source and being arranged to be cyclically switched from a blocking state to a conducting state in response to gate pulses generated by associated control means, comprising: a. level detecting means connected across said main electrodes of the valve and operative to provide a first signal only when the instantaneous magnitude of voltage across the valve exceeds a predetermined threshold level which is higher than the voltage drop across the valve when conducting; b. means for deriving a control voltage from said source, said control voltage deriving means including a capacitor coupled to all phases of the source and arranged to be charged therefrom while the instantaneous magnitude of source voltage is higher than an amount equivalent to the magnitude of said control voltage and to sustain said control voltage during any interval when the instantaneous magnitude of source voltage is lower than said amount; c. means for emitting an indicating signal when energized by said control voltage; d. switching means connected between said signal emitting means and capacitor and controlled by said first signal for causing said control voltage to energize said emitting means; and e. logic means having one input for receiving said indicating signal and having a second input responsive to the generation of said gate pulses, said logic means being dependent upon the contemporaneous states of both inputs for producing a predetermined output signal so long as said valve is in its conducting state.

Claim 11

The subject matter of claim 7 arranged to monitor the states of a plurality of electric valves which have corresponding first main electrodes connected in common to one side of the load and corresponding second main electrodes connected individually to the respective phases of the polyphase source, wherein: there is a separate level detecting means connecting across each of the respective valves, said switching means causes said control voltage to energize said indicating signal emitting means on concurrent operations of all of the level detecting means, and said logic means produces said output signal in response to the absence of said indicating signal and, concurrently, either the generation of a gate pulse or the presence of said output signal.

Claim 12

For use in conjunction with electric power conversion apparatus comprising a group of periodically conducting electric valves connected in a bridge configuration between a-c and d-c terminals, with a first one of said valves having its anode connected to a first a-c terminal and having its cathode connected to the positive d-c terminal of the bridge and with a second one of said valves having its anode connected to a different a-c terminal and its cathode connected to said positive d-c terminal, said a-c terminals being adapted to be connected to a polyphase alternating voltage system, and triggering means for cyclically generating a family of gate pulses and for sequentially applying said gate pulses to the respective valves of the bridge so as to trigger each valve From a blocking to a forward conducting state in synchronism with said alternating voltage, the forward current conducting period of each valve in turn being followed immediately by an interval of reverse voltage across the valve, improved means for monitoring the state of said bridge comprising: a. first means connected across said first valve and operative to provide a first signal when the instantaneous magnitude of voltage across that valve exceeds a predetermined threshold level which is higher than the voltage drop across the valve when conducting; b. second means connected across said second valve and operative to provide a second signal when the instantaneous magnitude of voltage across the second valve exceeds said threshold level; c. means controlled by said first and second signals for emitting a first indicating signal when said first and second means are concurrently operative, said indicating signal emitting means being unable to emit said first indicating signal in the absence of either said first signal or said second signal; and d. logic means coupled to the last-mentioned means and to said triggering means for producing a predetermined output signal in response to the absence of said first indicating signal and, concurrently, either the generation of any one of said gate pulses or the presence of said output signal, whereby said output signal is produced so long as either said first or second valve is conducting.

Claim 13

For use in conjunction with electric power conversion apparatus comprising a group of periodically conducting electric valves connected in a bridge configuration between a-c and d-c terminals, with a first one of said valves having its anode connected to a first a-c terminal and having its cathode connected to the positive d-c terminal of the bridge and with a second one of said valves having its anode connected to a different a-c terminal and its cathode connected to said positive d-c terminal, said a-c terminals being adapted to be connected to a polyphase alternating voltage system, and triggering means for cyclically generating a family of gate pulses and for sequentially applying said gate pulses to the respective valves of the bridge so as to trigger each valve From a blocking to a forward conducting state in synchronism with said alternating voltage, the forward current conducting period of each valve in turn being followed immediately by an interval of reverse voltage across the valve, improved means for monitoring the state of said bridge comprising: a. first means connected across said first valve and operative to provide a first signal when the instantaneous magnitude of voltage across that valve exceeds a predetermined threshold level which is higher than the voltage drop across the valve when conducting; b. second means connected across said second valve and operative to provide a second signal when the instantaneous magnitude of voltage across the second valve exceeds said threshold level; c. means controlled by said first and second signals for emitting a first indicating signal when said first and second means are concurrently operative, said indicating signal emitting means being unable to emit said first indicating signal in the absence of either said first signal or said second signal; and d. logic means coupled to the last-mentioned means and to said triggering means for producing a predetermined output signal in response to the absence of said first indicating signal and, concurrently, either the generation of any one of said gate pulses or the presence of said output signal, whereby said output signal is produced so long as either said first or second valve is conducting.

Claim 14

The subject matter of claim 9 wherein the apparatus comprises two groups of valves forming first and second duplicate bridges, with the positive d-c terminal of the first bridge being connected to the negative d-c terminal of the second bridge, and additional means for sequentially triggering the valves of the second bridge; wherein first and second means are provided for monitoring the states of the first and second bridges, respectively; and wherein there is provided means responsive to the output signal produced by the logic means of the second monitoring means for preventing the application of gate pulses to the valves of the first bridge.

Claim 15

The subject matter of claim 10 wherein the negative d-c terminal of the first bridge is connected to the positive d-c terminal of the second bridge, and wherein means is provided for preventing the application of gate pulses to the valves of the second bridge while the logic means of the first monitoring means is producing an output signal.

Claim 16

The subject matter of claim 9 wherein the apparatus comprises two groups of valves forming first and second duplicate bridges, with a first one of the valves of the second bridge being connected in inverse-parallel relationship with said first valve of the first bridge and a second one of the valves of said second bridge being connected in inverse-parallel relationship with said second valve of the first bridge, additional means for sequentially triggering the valves of the second bridge and means for alternatively activating the original and the additional triggering means, wherein the first and second means of the improved monitoring means are operative to provide their respective signals when there is voltage of either polarity across the respectively associated valves and the absolute magnitude thereof exceeds said threshold level; wherein said logic means is also coupled to said additional triggering means and is arranged to produce another output signal in response to the absence of said first indicating signal and, concurrently, either the triggering of a valve of the second bridge or the presence of said other output signal, whereby said other output signal is produced so long as either of the first and second valves of the second bridge is conducting; and wherein there are provided means responsive to said predetermined output signal for preventing the application of gate pulses to the valves of the second bridge and means responsive to said other output signal for preventing the application of gate pulses to the valVes of the first bridge.

Claim 17

For use in conjunction with electric power conversion apparatus comprising a group of periodically conducting electric valves connected in a bridge configuration between a-c and d-c terminals, with the first one of said valves having its cathode connected to the positive d-c terminal of the bridge, a second one of said valves having its anode connected to a different a-c terminal and its cathode connected to said positive d-c terminal, a third one of said valves having its anode connected to the negative d-c terminal of the bridge and its cathode connected to said first a-c terminal, and a fourth one of said valves having its anode connected to said negative d-c terminal and its cathode connected to said different a-c terminal, said a-c terminals being adapted to be connected to a polyphase alternating voltage system, and triggering means for cyclically generating a family of gate pulses and for sequentially applying said gate pulses to the respective valves of the bridge so as to trigger each valve from a blocking to a forward conducting state in synchronism with said alternating voltage, the forward current conducting period of each valve in turn being followed immediately by an interval of reverse voltage across that valve, improved means for monitoring the state of said bridge comprising: a. first means connected across said first valve and operative to provide a first signal when the instantaneous magnitude of voltage across that valve exceeds a predetermined threshold level which is higher than the voltage drop across the valve when conducting; b. second means connected across said second valve and operative to provide a second signal when the instantaneous magnitude of voltage across the second valve exceeds said threshold level; c. means controlled by said first and second signals for emitting a first indicating signal when said first and second means are concurrently operative; d. third means connected across said third valve and operative to provide a third signal when the instantaneous magnitude of voltage across said third valve exceeds said threshold level, e. fourth means connected across said fourth valve and operative to provide a fourth signal when the instantaneous magnitude of voltage across said fourth valve exceeds said threshold level, f. means controlled by said third and fourth signals for emitting a second indicating signal when said third and fourth means are concurrently operative; and g. logic means coupled to said triggering means and to both of said indicating signal producing means for producing a predetermined output signal in response to the absence of either of said first and second indicating signals and, concurrently, either the generation of any one of said gate pulses or the presence of said output signal, whereby said output signal is produced so long as one of said first, second, third, and fourth valves is conducting.

Claim 18

For use in conjunction with electric power conversion apparatus comprising a group of periodically conducting electric valves connected in a bridge configuration between a-c and d-c terminals, with the first one of said valves having its cathode connected to the positive d-c terminal of the bridge, a second one of said valves having its anode connected to a different a-c terminal and its cathode connected to said positive d-c terminal, a third one of said valves having its anode connected to the negative d-c terminal of the bridge and its cathode connected to said first a-c terminal, and a fourth one of said valves having its anode connected to said negative d-c terminal and its cathode connected to said different a-c terminal, said a-c terminals being adapted to be connected to a polyphase alternating voltage system, and triggering means for cyclically generating a family of gate pulses and for sequentially applying said gate pulses to the respective valves of the bridge so as to trigger each valve from a blocking to a forward conducting state in synchronism with said alternating voltage, the forward current conducting period of each valve in turn being followed immediately by an interval of reverse voltage across that valve, improved means for monitoring the state of said bridge comprising: a. first means connected across said first valve and operative to provide a first signal when the instantaneous magnitude of voltage across that valve exceeds a predetermined threshold level which is higher than the voltage drop across the valve when conducting; b. second means connected across said second valve and operative to provide a second signal when the instantaneous magnitude of voltage across the second valve exceeds said threshold level; c. means controlled by said first and second signals for emitting a first indicating signal when said first and second means are concurrently operative; d. third means connected across said third valve and operative to provide a third signal when the instantaneous magnitude of voltage across said third valve exceeds said threshold level, e. fourth means connected across said fourth valve and operative to provide a fourth signal when the instantaneous magnitude of voltage across said fourth valve exceeds said threshold level, f. means controlled by said third and fourth signals for emitting a second indicating signal when said third and fourth means are concurrently operative; and g. logic means coupled to said triggering means and to both of said indicating signal producing means for producing a predetermined output signal in response to the absence of either of said first and second indicating signals and, concurrently, either the generation of any one of said gate pulses or the presence of said output signal, whereby said output signal is produced so long as one of said first, second, third, and fourth valves is conducting.

Claim 19

Means for detecting the presence of voltage across a thyristor comprising: a. level detecting means conductively connected across the thyristor and operative to produce a first signal when there is voltage of either polarity across the thyristor and the absolute magnitude thereof exceeds a predetermined threshold level which is higher than the voltage drop across the thyristor when in its forward current conducting state; b. means including a capacitor connected across the thyristor for providing a continuously available control voltage, said capacitor being charged by voltage across the thyristor when in its blocking state; c. means for producing a second signal when energized by said control voltage, said second signal being electrically insulated from said first signal and said control voltage; and d. switching means controlled by said first signal for causing said control voltage to energize said second signal producing means on operation of said level detecting means.

Claim 20

Means for detecting the presence of voltage across a thyristor comprising: a. level detecting means conductively connected across the thyristor and operative to produce a first signal when there is voltage of either polarity across the thyristor and the absolute magnitude thereof exceeds a predetermined threshold level which is higher than the voltage drop across the thyristor when in its forward current conducting state; b. means including a capacitor connected across the thyristor for providing a continuously available control voltage, said capacitor being charged by voltage across the thyristor when in its blocking state; c. means for producing a second signal when energized by said control voltage, said second signal being electrically insulated from said first signal and said control voltage; and d. switching means controlled by said first signal for causing said control voltage to energize said second signal producing means on operation of said level detecting means.

Claim 21

In combination: a. a periodically conDucting thyristor having a pair of main electrodes adapted to be serially connected in an electric power circuit including a load and one phase of a polyphase alternating voltage source; b. gate pulse generating means operative on command to generate a gate pulse for triggering said thyristor; c. control means for cyclically effecting operation of said gate pulse generating means in synchronism with said alternating voltate, said control means including means for varying the time at which said control means commands operation of said gate pulse generating means each cycle; d. level detecting means connected across the main electrodes of said thyristor and operative whenever the instantaneous magnitude of voltage across the thyristor exceeds a predetermined threshold level which is higher than the voltage drop across the thyristor when conducting; e. means for deriving a control voltage from said source, said control voltage deriving means including an energy storage component coupled to all phases of the source and arranged to be charged therefrom while the instantaneous magnitude of source voltage is higher than an amount equivalent to the magnitude of said control voltage and to sustain said control voltage during any interval when the instantaneous magnitude of source voltage is lower than said amount; f. means operatively energized solely by said control voltage for emitting a voltage indicating signal when so energized; g. switching means connected between said control voltage deriving means and said signal emitting means for causing said control voltage to energize said last-mentioned means on operation of said level detecting means; and h. logic means coupled to both said control means and said voltage indicating signal emitting means for preventing said control means from effecting operation of said gate pulse generating means in the absence of a voltage indicating signal.

Claim 22

In combination: a. a periodically conDucting thyristor having a pair of main electrodes adapted to be serially connected in an electric power circuit including a load and one phase of a polyphase alternating voltage source; b. gate pulse generating means operative on command to generate a gate pulse for triggering said thyristor; c. control means for cyclically effecting operation of said gate pulse generating means in synchronism with said alternating voltate, said control means including means for varying the time at which said control means commands operation of said gate pulse generating means each cycle; d. level detecting means connected across the main electrodes of said thyristor and operative whenever the instantaneous magnitude of voltage across the thyristor exceeds a predetermined threshold level which is higher than the voltage drop across the thyristor when conducting; e. means for deriving a control voltage from said source, said control voltage deriving means including an energy storage component coupled to all phases of the source and arranged to be charged therefrom while the instantaneous magnitude of source voltage is higher than an amount equivalent to the magnitude of said control voltage and to sustain said control voltage during any interval when the instantaneous magnitude of source voltage is lower than said amount; f. means operatively energized solely by said control voltage for emitting a voltage indicating signal when so energized; g. switching means connected between said control voltage deriving means and said signal emitting means for causing said control voltage to energize said last-mentioned means on operation of said level detecting means; and h. logic means coupled to both said control means and said voltage indicating signal emitting means for preventing said control means from effecting operation of said gate pulse generating means in the absence of a voltage indicating signal.