Patent US3771041A successfully refreshed from Google Patents.
US3771041A
Expired / Lapsed
US
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Margin angle control for hvdc converter having improved valve current monitor
Assignee: CGEE ALSTHOM NORTH AMERICA Inc
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Filing: 1972-02-25
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Granted: 1973-11-06
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Expires: 1992-02-25
Abstract
Abstract A margin angle control for a power converter including a valve current monitor for deriving output electric signals representative of the current conducting interval of the thyristor devices comprising the power converter. An alternating current voltage monitor derives output electric signals representative of the voltages appearing across the respective thyristor devices so that by comparing the cessation of current flow through the respective thyristor devices to the point where the voltage across the device passes through zero potential during reversal of the polarity in the voltage across the respective thyristor device, a measure of the margin angle of the device is obtained. Margin angle signal developing circuits are described responsive to the valve current monitor and the voltage monitor for deriving output margin angle signals representative of the margin angles of the respective thyristor devices in the power converter. A selector circuit is responsive to the margin angle signal developing circuit and selects out that margin angle signal representative of the smallest margin angle. The smallest margin angle signal is then compared in a summing circuit to a first reference margin angle signal to develop an error margin angle control signal for normally controlling operation of the thyristor devices. A comparison circuit is coupled to the summing circuit and is responsive to the error margin angle control signal derived in the summing circuit and to a second reference margin angle signal for detecting severe reductions in the smallest margin angle control signal and deriving a second output control signal that is applied in addition to the first error margin angle control signal for providing fast responding control the operation of the converter. In a preferred embodiment a gain change circuit is included in the normal control regulation loop and is responsive to the error margin angle control signal for reducing the gain of the loop in response to a condition where the detected minimum margin angle is less than the reference minimum margin angle established by the first reference minimum margin angle signal whereby any tendency for the regulating system to overshoot and oscillate about a zero error condition, is minimized. The margin angle control is for use with a threephase bridge connected converter employing at least six thyristor devices with three sets of two thyristor devices connected as a valve pair for each phase of a three phase supply transformer winding. The valve current monitor comprises a conventional alternating current transformer inductively coupled to each valve pair and includes valve current signal shaping and separating circuits for shaping and separating the signal representative of the conduction intervals of the respective thyristor devices in each valve pair. A delay is introduced with respect to the valve current signals to cause these signals to extend over and include or drown out any spurious overshoot signal pulses induced in the current transformer winding as a result of thyristor turn-off, etc. Compensation of the extended time duration of the valve current signal pulse is then provided for at a later point in the margin angle control.
Inventors
- 👤 P Chadwick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:52
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/66; H02M7/68; H02M7/72; H02M7/75; H02M7/757; H02M7/7575; Y; Y02; Y02E; Y02E60/00; Y02E60/60
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
262 words
A margin angle control for a power converter including a combination valve current monitoring means coupled in circuit relationship with the conductivity controlled thyristor devices of a power converter for deriving valve current output electric signals representative of the current conducting periods of the respective thyristor devices, alternating current system voltage monitoring means coupled to said thyristor devices for deriving valve voltage output electric signals representative of the voltage appearing across the respective thyristor devices, the time duration of the interval between the cessation of current conduction through the respective thyristor devices and the passage through zero potential that occurs during reversal of the polarity in the voltage across the respective thyristor devices corresponding to the margin angle of the respective thyristor devices, charging circuit means responsive to said valve current monitoring means and said alternating current system voltage monitoring means for charging to a voltage value representative of the margin angle of the respective thyristor devices, means for instantaneously discharging said chArging circuit means at the termination of the conducting intervals of the respective thyristor devices and in advance of charging the charging circuit means whereby the margin angle of the respective thyristor devices is freshly sampled for each conducting interval of the device and carry-over of a previous sample margin angle voltage value is eliminated, and selector circuit means responsive to all of the charging circuit means for selecting that margin angle voltage value representative of the smallest margin angle and supplying the same as an output margin angle control signal for use in controlling operation of the thyristor devices.
Claim 2
Dependent Claim
262 words
A margin angle control for a power converter including a combination valve current monitoring means coupled in circuit relationship with the conductivity controlled thyristor devices of a power converter for deriving valve current output electric signals representative of the current conducting periods of the respective thyristor devices, alternating current system voltage monitoring means coupled to said thyristor devices for deriving valve voltage output electric signals representative of the voltage appearing across the respective thyristor devices, the time duration of the interval between the cessation of current conduction through the respective thyristor devices and the passage through zero potential that occurs during reversal of the polarity in the voltage across the respective thyristor devices corresponding to the margin angle of the respective thyristor devices, charging circuit means responsive to said valve current monitoring means and said alternating current system voltage monitoring means for charging to a voltage value representative of the margin angle of the respective thyristor devices, means for instantaneously discharging said chArging circuit means at the termination of the conducting intervals of the respective thyristor devices and in advance of charging the charging circuit means whereby the margin angle of the respective thyristor devices is freshly sampled for each conducting interval of the device and carry-over of a previous sample margin angle voltage value is eliminated, and selector circuit means responsive to all of the charging circuit means for selecting that margin angle voltage value representative of the smallest margin angle and supplying the same as an output margin angle control signal for use in controlling operation of the thyristor devices.
Claim 3
Dependent Claim
43 words
A margin angle control according to claim 1, wherein said charging circuit means includes a constant current source for linearly charging the charging circuit means to a voltage value dependent upon the time duration of the margin angle of the respective thyristor devices.
Claim 4
Dependent Claim
92 words
A margin angle control according to claim 1, further including first summing circuit means for summing together the selected smallest margin angle control signal with a first reference margin angle signal to derive an error margin angle control signal for normally controlling operation of the thyristor devices, and gain change circuit means responsive to the error margin angle control signal for reducing the gain of the normal control regulation loop of the margin angle control in response to error margin angle control signals which are indicative of a subnormal minimum margin angle.
Claim 5
Dependent Claim
124 words
A margin angle control according to claim 3, wherein said charging circuit means includes a constant current source for linearly charging the charging circuit means to a voltage value dependent upon the time duration of the margin angle of the respective thyristor devices, and further including second summing circuit means responsive to the selected smallest margin angle control signal and to a second reference signal for detecting severe changes in the smallest margin angle control signal and deriving a second output error margin angle control signal, and fast responding control means responsive to said second output error margin angle control signal for providing fast responding control over firing angles of the thyristor devices upon a severe change in the minimum margin angle. being detected.
Claim 6
Dependent Claim
117 words
A margin angle control according to claim 1, further including summing circuit means for summing together the selected smallest margin angle control signal with a first reference margin angle signal to derive an error margin angle control signal for normally controlling operation of the thyristor devices, and fast responding control signal pulse generating means operative when the selected smallest margin angle becomes smaller than a second reference margin angle value for deriving an output control pulse of constant amplitude and variable time duration dependent upon the magnitude of the error control signal and that provides fast responding control over the firing angles of the thyristor devices in response to a severe change in the minimum margin angle.
Claim 7
Dependent Claim
284 words
A margin angle control for a power converter including in combination valve current monitoring means coupled in circuit relationship with the conductivity controlled thyristor devices of a power converter for deriving valve current output electric signals representative of the current conducting period of the respective thyristor devices, alternating current system voltage monitoring means coupled to said thyristor devices for deriving valve voltage output electric signals representative of the voltages appearing across the respective thyristor devices, margin angle monitor means responsive to said valve current monitoring means and said alternating current system voltage monitoring means for deriving output margin angle electric signals representative of the duration of the interval between the cessation of current conduction through the respective thyristor devices and the passage through zero potential that occurs dUring reversal of the polarity in the voltage across the respective thyristor devices and which corresponds to the margin angle of the respective thyristor devices, charging circuit means responsive to the respective margin angle electric signals for charging to a voltage value representative of the margin angle of the respective thyristor devices, means for instantaneously discharging said charging circuit means at the termination of the conducting intervals of the respective thyristor devices and in advance of charging the charging circuit means whereby the margin angle of the respective thyristor devices is freshly sampled for each conducting interval of a device and carry-over of a previous sample margin angle voltage value is eliminated, and selector circuit means responsive to all of the charging circuit means for selecting that margin angle voltage value representative of the smallest margin angle and supplying the same as an output margin angle control signal for use in controlling operation of the thyristor devices.
Claim 8
Dependent Claim
284 words
A margin angle control for a power converter including in combination valve current monitoring means coupled in circuit relationship with the conductivity controlled thyristor devices of a power converter for deriving valve current output electric signals representative of the current conducting period of the respective thyristor devices, alternating current system voltage monitoring means coupled to said thyristor devices for deriving valve voltage output electric signals representative of the voltages appearing across the respective thyristor devices, margin angle monitor means responsive to said valve current monitoring means and said alternating current system voltage monitoring means for deriving output margin angle electric signals representative of the duration of the interval between the cessation of current conduction through the respective thyristor devices and the passage through zero potential that occurs dUring reversal of the polarity in the voltage across the respective thyristor devices and which corresponds to the margin angle of the respective thyristor devices, charging circuit means responsive to the respective margin angle electric signals for charging to a voltage value representative of the margin angle of the respective thyristor devices, means for instantaneously discharging said charging circuit means at the termination of the conducting intervals of the respective thyristor devices and in advance of charging the charging circuit means whereby the margin angle of the respective thyristor devices is freshly sampled for each conducting interval of a device and carry-over of a previous sample margin angle voltage value is eliminated, and selector circuit means responsive to all of the charging circuit means for selecting that margin angle voltage value representative of the smallest margin angle and supplying the same as an output margin angle control signal for use in controlling operation of the thyristor devices.
Claim 9
Dependent Claim
128 words
A margin angle control according to claim 6, further including first summing circuit means for summing together the selected smallest margin angle control signal with a first reference margin angle signal to derive an error margin angle control signal for normally controlling operation of the thyristor devices, second summing circuit means responsive to the selected smallest margin angle control signal and to a second reference margin angle signal for detecting severe changes in the smallest margin angle control signal and deriving a second output error margin angle control signal, and fast responding control circuit means responsive to said second output error margin angle control signal for providing fast responding control over the operation of the thyristor devices upon a severe change in the minimum margin angle being detected.
Claim 10
Dependent Claim
138 words
A margin angle control according to claim 6, wherein said margin angle monitor means derives squarewave-shaped electric output signals whose duration is represenative of the margin angle of the respective thyristor devices, said squarewave-shaped signals upon being supplied to said charging circuit means producing a saw toothed-notched waveform electric output signal whose magnitude is representative of the margin angle of the respective thyristor devices, and said selector circuit means further includes notch blanking means responsive to the selected minimum margin angle sawtoothed-notched waveform electric output signal and responsive to the squarewaved-shaped output signals supplied from the margin angle monitor means for blanking out the sawtooth-wave notch appearing in the output signal waveform from the charging circuit means whereby a substantially continuous direct current output minimum angle control signal is derived from the output of the selector circuit means.
Claim 11
Dependent Claim
170 words
A margin angle control according to claim 8, further including first summing circuit means for summing together the selected smallest margin angle control signal with a first reference margin angle signal to derive an error margin angle control signal for normally controlling operation of the converter, gain change circuit means responsive to the error margin angle control signal for reducing the gain of the normal control regulation loop in response to error margin angle control signals in the increasing direction which are indicative of increases in the minimum margin angle, and second summing circuit means responsive to the selected smallest margin angle control signal and to a second reference signal for detecting severe changes in the smallest margin angle control signal and deriving a second output error margin angle control signal, and fast responding control means responsive to said second output error margin angle control signal for providing fast responding control over the firing angles of the thyristor devices upon a severe change in the minimum margin angle being detected.
Claim 12
Dependent Claim
189 words
A margin angle control according to claim 9, wherein tHe power converter comprises a three-phase bridge connected converter with each bridge comprising at least six thyristor devices and having three sets of two thyristor devices connected as a valve pair for each phase of a three-phase transformer winding comprising a part of the converter, and wherein said valve current monitoring means comprises a conventional alternating current transformer inductively coupled to each valve pair, valve current signal shaping and separating circuit means coupled to the respective current transformers of each valve pair for squarewave-shaping the signals produced thereby and separating the signals into two separate signals representative of the conduction intervals of each of the respective thyristor devices comprising the valve pair, and delay means coupled to the respective signal wave shaping and separating circuit means for extending the duration of the squarewave-shaped electric signals produced thereby by a predetermined amount to include and drown out spurious signal pulses induced in the current transformer windings as a result of thyristor device turn-off and the like to thereby obviate the production of false and erraneous output current conduction indicating signal pulses.
Claim 13
Dependent Claim
52 words
A margin angle control according to claim 10, wherein the value of the first and second reference margin angle signals are adjusted to compensate for the extended duration of the valve current signal pulses produced as a result of the delay introduced in the valve current signal shaping and separating circuit means.
Claim 14
Dependent Claim
38 words
A margin angle control according to claim 11, wherein the power converter comprises a high voltage direct current to alternating current and alternating current to direct current converter capable of operation in either an inverting or rectifying mode.
Claim 15
Dependent Claim
297 words
A margin angle control for a power converter including in combination valve current monitoring means coupled in circuit relationship with the conductivity controlled thryistor devices of a power converter for deriving valve current output electric signals representative of the current conducting periods of the respective thyristor devices, alternating current system voltage monitoring means coupled to said thyristor devices for deriving valve voltage output electric signals representative of the voltage appearing across the respective thyristor devices, the duration of the interval between the cessation of current conduction through the respective thyristor devices and the passage through zero potential that occurs during reversal of the polarity in the voltage across the respective thyristor devices corresponding to the margin angle of the respective thyristor devices, margin angle signal deriving means responsive to said valve current monitoring means and said alternating current system voltage monitoring means for deriving output margin angle signals representative of the margin angles of the respective thyristor devices, selector circuit means responsive to said margin angle signal deriving means for selecting that margin angle signal representative of the smallest margin angle, first summing circuit means for summing together the selected smallest margin angle control signal with a first reference margin angle signal to derive an error margin angle control signal for normally controlling operation of the thyristor devices, second summing circuit means responsive to the selected smallest margin angle control signal and to a second reference signal for detecting severe changes in the smallest margin angle control signal and deriving a second output error margin angle control signal, and fast responding control circuit means responsive to said second output error margin angle control signal for providing fast responding control over the operation of the thyristor devices upon a severe change in the minimum margin angle being detected.
Claim 16
Dependent Claim
297 words
A margin angle control for a power converter including in combination valve current monitoring means coupled in circuit relationship with the conductivity controlled thryistor devices of a power converter for deriving valve current output electric signals representative of the current conducting periods of the respective thyristor devices, alternating current system voltage monitoring means coupled to said thyristor devices for deriving valve voltage output electric signals representative of the voltage appearing across the respective thyristor devices, the duration of the interval between the cessation of current conduction through the respective thyristor devices and the passage through zero potential that occurs during reversal of the polarity in the voltage across the respective thyristor devices corresponding to the margin angle of the respective thyristor devices, margin angle signal deriving means responsive to said valve current monitoring means and said alternating current system voltage monitoring means for deriving output margin angle signals representative of the margin angles of the respective thyristor devices, selector circuit means responsive to said margin angle signal deriving means for selecting that margin angle signal representative of the smallest margin angle, first summing circuit means for summing together the selected smallest margin angle control signal with a first reference margin angle signal to derive an error margin angle control signal for normally controlling operation of the thyristor devices, second summing circuit means responsive to the selected smallest margin angle control signal and to a second reference signal for detecting severe changes in the smallest margin angle control signal and deriving a second output error margin angle control signal, and fast responding control circuit means responsive to said second output error margin angle control signal for providing fast responding control over the operation of the thyristor devices upon a severe change in the minimum margin angle being detected.
Claim 17
Dependent Claim
194 words
A margin angle control according to claim 13, wherein the power converter comprises a three-phase bridge connected converter with each bridge compriSing at least six thyristor devices and having three sets of two thyristor devices connected as a valve pair for each phase of a three-phase transformer supply winding comprising a part of the converter and wherein said valve current monitoring means comprises a conventional alternating current transformer inductively coupled to each valve pair, valve current signal shaping and separating circuit means coupled to the respective current transformers of each valve pair for squarewave-shaping the signals produced thereby and separating the signals into two separate signals representative of the conduction intervals of each of the respective thyristor devices comprising the valve pair, and delay means coupled to the respective valve current signal wave shaping and separating circuit means for extending the duration of the squarewave-shaped electric signals produced thereby by a predetermined amount to include and drown out spurious overshoot signal pulses induced in the current transformer windings as a result of thyristor device turn-off and the like to thereby obviate the production of false and erroneous output valve current conduction indicating signal pulses.
Claim 18
Dependent Claim
42 words
A margin angle control according to claim 14, further including means for compensating for the extended time duration of the valve current output squarewave electric signal pulses representative of the current conducting periods of the respective thyristor devices in the power converter.
Claim 19
Dependent Claim
188 words
A low cost valve current monitor for a three-phase bridge connected power converter with each bridge comprising at least six thyristor devices and having three sets of two thyristor devices connected as a valve pair for each phase of a three-phase transformer winding comprising a part of the bridge power converter, said valve current monitor comprising an alternating current current transformer inductively coupled to each valve pair of the bridge power converter, valve current signal shaping and separating circuit means coupled to the respective current transformers of each valve pair for squarewave-shaping the signals produced thereby and separating the signals into two separate signals representative of the conduction intervals of each of the respective thyristor devices comprising the valve pair, and delay means coupled to the respective signal wave shaping and separating circuit means for extending the duration of the squarewave-shaped electric signals produced thereby by a predetermined amount to include and drown out spurious signal pulses induced in the current transformer windings as a result of thyristor device turn-off and the like to thereby obviate the production of false or erroneous valve current conduction indicating signal pulses.
Claim 20
Dependent Claim
188 words
A low cost valve current monitor for a three-phase bridge connected power converter with each bridge comprising at least six thyristor devices and having three sets of two thyristor devices connected as a valve pair for each phase of a three-phase transformer winding comprising a part of the bridge power converter, said valve current monitor comprising an alternating current current transformer inductively coupled to each valve pair of the bridge power converter, valve current signal shaping and separating circuit means coupled to the respective current transformers of each valve pair for squarewave-shaping the signals produced thereby and separating the signals into two separate signals representative of the conduction intervals of each of the respective thyristor devices comprising the valve pair, and delay means coupled to the respective signal wave shaping and separating circuit means for extending the duration of the squarewave-shaped electric signals produced thereby by a predetermined amount to include and drown out spurious signal pulses induced in the current transformer windings as a result of thyristor device turn-off and the like to thereby obviate the production of false or erroneous valve current conduction indicating signal pulses.
Claim 21
Dependent Claim
44 words
A low cost valve current monitor according to claim 16 further including means to compensate for the extended time duration of the valve durrent signal pulses produced as a result of the delay introduced in the valve current signal shaping and separating circuit means.
Claim 22
Dependent Claim
250 words
In combination: a converter comprising a plurality of electric current conducting valves connected in a bridge configuration between AC and DC electric power conductors, said valves being arranged to be cyclically fired in a predetermined sequence; controllable firing means for sequentially firing said valves at desired firing angles; means for deriving output margin angle signals representative of the margin angles of the respective valves of said bridge; selector circuit means responsive to said margin angle signal deriving means for selecting that margin angle signal representative of the smallest margin angle; summing circuit means for summing together the selected smallest margin angle signal with a reference margin angle signal to derive an error signal for normally controlling operation of said controllable firing means so as to advance or to retard the firing angles as required to minimize said error; fast responding control circuit means operative to provide additional control over the operAtion of said controllable firing means, said fast responding control circuit means being effective, when operative, to cause said controllable firing means rapidly to advance said firing angle an amount proportional to the magnitude of said error signal; and means for activating operation of said fast responding control circuit in immediate response to the selected smallest margin angle decreasing to a predetermined level below the level of the reference margin angle established by said reference margin angle signal, whereby a severe reduction in the smallest margin angle is rapidly corrected by the operation of said fast responding control circuit means.
Claim 23
Dependent Claim
250 words
In combination: a converter comprising a plurality of electric current conducting valves connected in a bridge configuration between AC and DC electric power conductors, said valves being arranged to be cyclically fired in a predetermined sequence; controllable firing means for sequentially firing said valves at desired firing angles; means for deriving output margin angle signals representative of the margin angles of the respective valves of said bridge; selector circuit means responsive to said margin angle signal deriving means for selecting that margin angle signal representative of the smallest margin angle; summing circuit means for summing together the selected smallest margin angle signal with a reference margin angle signal to derive an error signal for normally controlling operation of said controllable firing means so as to advance or to retard the firing angles as required to minimize said error; fast responding control circuit means operative to provide additional control over the operAtion of said controllable firing means, said fast responding control circuit means being effective, when operative, to cause said controllable firing means rapidly to advance said firing angle an amount proportional to the magnitude of said error signal; and means for activating operation of said fast responding control circuit in immediate response to the selected smallest margin angle decreasing to a predetermined level below the level of the reference margin angle established by said reference margin angle signal, whereby a severe reduction in the smallest margin angle is rapidly corrected by the operation of said fast responding control circuit means.
Claim 24
Dependent Claim
210 words
In combination: a converter comprising a plurality of electric current conducting valves connected in a bridge configuration between AC and DC electric power conductors, said valves being arranged to be cyclically fired in a predetermined sequence; controllable means for sequentially firing said valves at desired firing angles; means for deriving output margin angle signals representative of the margin angles of the respective valves of said bridge; selector circuit means responsive to said margin angle signal deriving means for selecting that margin angle signal representative of the smallest margin angle; summing circuit means for summing together the selected smallest margin angle signal with a reference margin angle signal to derive an error signal for normally controlling operation of said firing means so as to advance or to retard the firing angles as required to minimize said error, and gain change circuit means for reducing the gain of the regulating loop comprising the converter, the margin angle signal deriving means, the summing circuit means, and the controllable firing circuit means in response to an error signal indicative of the selected minimum margin angle being smaller than a predetermined amount established by the reference margin angle signal whereby tendency to overshoot and oscillation of the system about a zero error condition is minimized.
Claim 25
Dependent Claim
210 words
In combination: a converter comprising a plurality of electric current conducting valves connected in a bridge configuration between AC and DC electric power conductors, said valves being arranged to be cyclically fired in a predetermined sequence; controllable means for sequentially firing said valves at desired firing angles; means for deriving output margin angle signals representative of the margin angles of the respective valves of said bridge; selector circuit means responsive to said margin angle signal deriving means for selecting that margin angle signal representative of the smallest margin angle; summing circuit means for summing together the selected smallest margin angle signal with a reference margin angle signal to derive an error signal for normally controlling operation of said firing means so as to advance or to retard the firing angles as required to minimize said error, and gain change circuit means for reducing the gain of the regulating loop comprising the converter, the margin angle signal deriving means, the summing circuit means, and the controllable firing circuit means in response to an error signal indicative of the selected minimum margin angle being smaller than a predetermined amount established by the reference margin angle signal whereby tendency to overshoot and oscillation of the system about a zero error condition is minimized.
Claim 26
Independent Claim
170 words
The method of controlling a converter comprised by a plurality of electric current conducting thyristor valves connected in a bridge configuration between AC and DC electric power conductors and arranged to be cyclically fired in a predetermined sequence, the method comprising deriving output margin angle signals representative of the margin angles of the respective thyristor valves of the bridge immediately following each thyristor valve current conduction interval, clearing previously sensed and stored margin angle signals immediately in advance of sensing and holding a new margin angle signal for a respective valve resulting from the latest valve firing, sensing and storing the actual value of each margin angle signal resulting from the latest thyristor valve firing with no carry-over from one firing to the next to provide a freshly up-dated margin angle signal sample associated with each individual valve firing, continuously sampling the stored margin angle signals and selecting that signal representative of the minimum margin angle for controlling the firing angles of the thyristor valves in a fast responding manner.
Claim 27
Independent Claim
170 words
The method of controlling a converter comprised by a plurality of electric current conducting thyristor valves connected in a bridge configuration between AC and DC electric power conductors and arranged to be cyclically fired in a predetermined sequence, the method comprising deriving output margin angle signals representative of the margin angles of the respective thyristor valves of the bridge immediately following each thyristor valve current conduction interval, clearing previously sensed and stored margin angle signals immediately in advance of sensing and holding a new margin angle signal for a respective valve resulting from the latest valve firing, sensing and storing the actual value of each margin angle signal resulting from the latest thyristor valve firing with no carry-over from one firing to the next to provide a freshly up-dated margin angle signal sample associated with each individual valve firing, continuously sampling the stored margin angle signals and selecting that signal representative of the minimum margin angle for controlling the firing angles of the thyristor valves in a fast responding manner.
Claim 28
Dependent Claim
92 words
The method according to claim 20, further comprising comparing the selected minimum margin angle signal to a pre-set reference signal and deriving an error control signal for advancing or retarding the firing angles of the individual thyristor valves so as to reduce the magnitude of the error control signal towards zero, and differentially treating the error control signal whereby the gain of the overall control is increased for changes in the minimum margin angle in the increasing direction and overshoot and oscillation of the control about a zero error condition is minimized.
Claim 29
Dependent Claim
58 words
The method according to claim 21, further comprising effectively comparing the selected minimum margin angle signal to a second pre-set reference signal and deriving a second control signal that is proportional to the magnitude of said eRror signal for quickly advancing the firing angles of the thyristor valves in response to the second pre-set reference signal being exceeded.
Claim 30
Dependent Claim
96 words
The method according to claim 20, further comprising comparing the selected minimum margin angle signal to a pre-set normal reference signal and deriving an error control signal that is proportional to the difference for advancing or retarding the firing angles of the individual thyristor valves so as to reduce the magnitude of the error control signal towards zero, and deriving a control signal pulse for additionally advancing said firing angles an increment dependent upon the magnitude of said error signal in response to sensing a margin angle smaller than a predetermined critical minimum margin angle value.
Claim 31
Dependent Claim
230 words
In combination: a converter comprising a plurality of electric current conducting valves connected in a bridge configuration between AC and DC electric power conductors, said valves being arranged to be cyclically fired in a predetermined sequence; controllable means for sequentially firing said valves at desired firing angles; means for deriving output margin angle signals representative of the actual margin angles of the respective valves of said bridge; selector circuit means connected to said margin angle signal deriving means for selecting that margin angle signal representative of the minimum actual margin angle; summing circuit means for comparing the selected minimum margin angle signal with a reference signal representative of a desired margin angle to derive an error signal indicative of the difference therebetween, said firing means being responsive to said error signal for advancing or retarding the firing angles as required to minimize said difference, and gain change circuit means for controlling the gain of the regulating loop comprising the converter, the margin angle signal deriving means, the summing circuit means, and the controllable firing means as a function of the value of said error signal, said gain change circuit means being operative to establish a predetermined minimum gain when the error signal is indicative of a nearly zero error condition and to establish a predetermined highest gain whenever the selected minimum margin angle is larger than a first predetermined angle.
Claim 32
Dependent Claim
230 words
In combination: a converter comprising a plurality of electric current conducting valves connected in a bridge configuration between AC and DC electric power conductors, said valves being arranged to be cyclically fired in a predetermined sequence; controllable means for sequentially firing said valves at desired firing angles; means for deriving output margin angle signals representative of the actual margin angles of the respective valves of said bridge; selector circuit means connected to said margin angle signal deriving means for selecting that margin angle signal representative of the minimum actual margin angle; summing circuit means for comparing the selected minimum margin angle signal with a reference signal representative of a desired margin angle to derive an error signal indicative of the difference therebetween, said firing means being responsive to said error signal for advancing or retarding the firing angles as required to minimize said difference, and gain change circuit means for controlling the gain of the regulating loop comprising the converter, the margin angle signal deriving means, the summing circuit means, and the controllable firing means as a function of the value of said error signal, said gain change circuit means being operative to establish a predetermined minimum gain when the error signal is indicative of a nearly zero error condition and to establish a predetermined highest gain whenever the selected minimum margin angle is larger than a first predetermined angle.
Claim 33
Dependent Claim
56 words
The combination according to claim 24 wherein said gain change circuit means is also operative to establish a predetermined gain that is lower than said highest gain but not as low as said minimum gain whenever the selected minimum margin angle is smaller than a second predetermined angle which is less than said desired margin angle.
Claim 34
Dependent Claim
36 words
The combination according to claim 25 wherein said gain change circuit means is operative to establish said predetermined minimum gain whenever the selected minimum margin angle is in a range between said first and second angles.
Claim 35
Dependent Claim
175 words
A valve current monitor for at least one pair of alternately conducting electric valves adapted to be connected to one phase of a polyphase electric power system by means of an alternating current conductor in which current will flow in one direction when one valve of said pair is conducting and in the opposite direction when the other valve is conducting, said current monitor comprising an alternating current transformer inductively coupled to said conductor, valve current signal shaping and separating circuit means coupled to said current transformer for squarewave-shaping the signals that are induced in the secondary thereof as a result of valve current and for producing two separate output signals representative of the intervals that the respective valves of the valve pair are conducting forward currents, and delay means coupled to the signal wave shaping and separating circuit means and operative upon the commencement of the squarewave-shaped electric signals for delaying the start of each of said output signals until the corresponding valve current indicating signal has persisted for a predetermined length of time.
Claim 36
Dependent Claim
175 words
A valve current monitor for at least one pair of alternately conducting electric valves adapted to be connected to one phase of a polyphase electric power system by means of an alternating current conductor in which current will flow in one direction when one valve of said pair is conducting and in the opposite direction when the other valve is conducting, said current monitor comprising an alternating current transformer inductively coupled to said conductor, valve current signal shaping and separating circuit means coupled to said current transformer for squarewave-shaping the signals that are induced in the secondary thereof as a result of valve current and for producing two separate output signals representative of the intervals that the respective valves of the valve pair are conducting forward currents, and delay means coupled to the signal wave shaping and separating circuit means and operative upon the commencement of the squarewave-shaped electric signals for delaying the start of each of said output signals until the corresponding valve current indicating signal has persisted for a predetermined length of time.
Claim 37
Dependent Claim
44 words
A valve currEnt monitor according to claim 27 in which said signal wave shaping and separating circuit means includes additional means operative upon the termination of the squarewave-shaped electric signals for extending the duration of each of the output signals by a predetermined amount.
Claim 38
Dependent Claim
141 words
A valve current monitor for at least one pair of alternately conducting electric valves adapted to be connected to one phase of a polyphase electric power system by means of an alternating current conductor in which current will flow in one direction when one valve of said pair is conducting and in the opposite direction when the other valve is conducting, said current monitor comprising a current transformer inductively coupled to said conductor, and valve current signal shaping and separating circuit means coupled to said current transformer for squarewave-shaping the signals induced therein and producing two separate output signals representing respectively the forward current conducting intervals of the two valves comprising said pair, said signal shaping and separating circuit means including cross-coupling means operative whenever either one of said two output signals is being produced for inhibiting the other output signal.
Claim 39
Dependent Claim
141 words
A valve current monitor for at least one pair of alternately conducting electric valves adapted to be connected to one phase of a polyphase electric power system by means of an alternating current conductor in which current will flow in one direction when one valve of said pair is conducting and in the opposite direction when the other valve is conducting, said current monitor comprising a current transformer inductively coupled to said conductor, and valve current signal shaping and separating circuit means coupled to said current transformer for squarewave-shaping the signals induced therein and producing two separate output signals representing respectively the forward current conducting intervals of the two valves comprising said pair, said signal shaping and separating circuit means including cross-coupling means operative whenever either one of said two output signals is being produced for inhibiting the other output signal.
Claim 40
Dependent Claim
35 words
The valve current monitor according to claim 29, further including delay means operative upon the termination of the squarewave-shaped electric signals for extending the duration of each of the output signals by a predetermined amount.
Claim 41
Dependent Claim
57 words
A valve current monitor according to claim 29, further including delay means coupled to the signal shaping and separating circuit means and operative upon the commencement of the squarewave-shaped electric signals for delaying the start of each of said output signals until the signal induced in said current transformer has persisted for a predetermined length of time.
Claim 42
Dependent Claim
44 words
The valve current monitor according to claim 31, further including means coupled to said signal shaping and separating circuit means and operative upon the termination of the squarewave-shaped electric signals for extending the duration of each of said output signals by a predetermined amount.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-05 | 1977-05-07 | 1977-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-05 | 1981-05-07 | 1981-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-05 | 1985-05-07 | 1985-11-06 | $7700.00 | Window Closed / Lapsed |