US3882369A
Expired / Lapsed
US
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Control of cycloconverter systems having a parallel resonant commutation circuit
Assignee: General Electric Co
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Filing: 1973-11-28
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Granted: 1975-05-06
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Expires: 1993-11-28
Abstract
Abstract A high frequency link cycloinverter and cycloconverter system having a parallel resonant comutation circuit operated at a variable frequency to control the reactive power available for commutation of the thyristors or other controlled power devices. A firing circuit component for computing the timing of a cycloconverter firing angle retard limit signal for an incoming device provides as a minimum a predetermined constant turn-off time for the outgoing device. For the cycloinverter system added turn-off time is computed to allow for simultaneous inverter and cycloconverter commutations at the retard limit. The control circuit and method utilizes sensed instantaneous power circuit parameters from which the state of the commutating capacitor voltage can be predicted, and a computation circuit for timing the generation of the retard limit signal.
Inventors
- 👤 William Mcmurray
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 04:33
CPC Classifications
H; H02; H02M; H02M5/00; H02M5/02; H02M5/04; H02M5/22; H02M5/25; H02M5/27; H02M5/271
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
154 words
A cascaded power converter system comprising a first power converter circuit and a second phase controlled converter power circuit each having a plurality of controlled power devices that are rendered conductive in sequence at a variable frequency to produce a desired output, parallel resonant commutation circuit means connected in a link between said first and second converter circuits and including commutation instance means and parallel commutating capacitor means for supplying a variable amount of reactive power to selectively render said controlled power devices nonconductive, and a firing circuit comprising means for generating a phase controlled converter firing angle retard limit signal which is comprised by a constant turn-off time control circuit for computing an approximately constant turn-off time for said power converter circuit controlled power devices, and further includes additional control circuitry for computing added time for turn-off to obtain approximately simultaneous turn-off of a selected first and second power circuit controlled power device.
Claim 2
Dependent Claim
154 words
A cascaded power converter system comprising a first power converter circuit and a second phase controlled converter power circuit each having a plurality of controlled power devices that are rendered conductive in sequence at a variable frequency to produce a desired output, parallel resonant commutation circuit means connected in a link between said first and second converter circuits and including commutation instance means and parallel commutating capacitor means for supplying a variable amount of reactive power to selectively render said controlled power devices nonconductive, and a firing circuit comprising means for generating a phase controlled converter firing angle retard limit signal which is comprised by a constant turn-off time control circuit for computing an approximately constant turn-off time for said power converter circuit controlled power devices, and further includes additional control circuitry for computing added time for turn-off to obtain approximately simultaneous turn-off of a selected first and second power circuit controlled power device.
Claim 3
Dependent Claim
200 words
A high frequency link cycloinverter system comprising an inverter power circuit having at least a pair of thyristors that are alternately rendered conductive at a variable frequency, a polyphase cycloconverter power circuit having in each phase a plurality of thyristors that are rendered conductive in sequence at a variable frequency to produce a desired output, intermediate parallel resonant commutation means connected in a link between said inverter and cycloverter circuits and including commutating inductance means and parallel commutating capacitor means for supplying a variable amount of reactive power to selectively render said thyristors nonconductive, and a firing circuit comprising retard limit signal means for generating a firing angle retard limit signal for each cycloconverter phase, said retard limit signal means including a constant turn-off time control Circuit for computing the timing of firing signals for each incoming inverter thyristor to obtain an approximately constant turn-off time for each corresponding outgoing inverter thyristor, and further including an additional control circuit for computing the timing of firing signals to selected incoming cycloconverter thyristors at the retard limit to provide added turn-off time for each corresponding outgoing cycloconverter thyristor at least sufficient to commutate current from the outgoing to the incoming cycloconverter thyristor.
Claim 4
Dependent Claim
200 words
A high frequency link cycloinverter system comprising an inverter power circuit having at least a pair of thyristors that are alternately rendered conductive at a variable frequency, a polyphase cycloconverter power circuit having in each phase a plurality of thyristors that are rendered conductive in sequence at a variable frequency to produce a desired output, intermediate parallel resonant commutation means connected in a link between said inverter and cycloverter circuits and including commutating inductance means and parallel commutating capacitor means for supplying a variable amount of reactive power to selectively render said thyristors nonconductive, and a firing circuit comprising retard limit signal means for generating a firing angle retard limit signal for each cycloconverter phase, said retard limit signal means including a constant turn-off time control Circuit for computing the timing of firing signals for each incoming inverter thyristor to obtain an approximately constant turn-off time for each corresponding outgoing inverter thyristor, and further including an additional control circuit for computing the timing of firing signals to selected incoming cycloconverter thyristors at the retard limit to provide added turn-off time for each corresponding outgoing cycloconverter thyristor at least sufficient to commutate current from the outgoing to the incoming cycloconverter thyristor.
Claim 5
Dependent Claim
89 words
A converter system according to claim 2 wherein said control circuits comprise sensing means for sensing the instantaneous voltage of said commutating capacitor means and for sensing selected instantaneous power circuit currents indicative of the commutating capacitor means current after the firing of each incoming inverter thyristor and each incoming cycloconverter thyristor fired at the retard limit, computation means for producing a cyclically varying retard limit control signal, and comparing means for comparing said retard limit control signal with a reference and generating said firing angle retard limit signal.
Claim 6
Dependent Claim
58 words
A converter system according to claim 3 wherein said sensing and computation means are provided by potential and current transformers, each current transformer having an associated burden resistor coupled across its secondary winding which is in turn coupled in series with each potential transformer secondary winding to form an analog circuit for producing said retard limit control signal.
Claim 7
Dependent Claim
69 words
A converter system according to claim 2 wherein said constant turn-off control circuit comprises sensing means for sensing the instantaneous voltage of said commutating capacitor means and for sensing at least one instantaneous inverter power circuit current indicative of the commutating capacitor means current after the firing of each incoming inverter thyristor, and said additional control circuit comprises sensing means for sensing the instantaneous cycloconverter current in each phase.
Claim 8
Dependent Claim
36 words
A converter system according to claim 5 wherein said sensing means in said additional control circuit comprises individual current sensors for each cycloconverter phase whereby separate firing angle retard limit signals are generated for each phase.
Claim 9
Dependent Claim
41 words
A converter system according to claim 5 wherein said sensing means in said additional control circuit comprises a common current sensor for sensing the total current in all the cycloconverter phases whereby a single firing angle retard limit signal is generated.
Claim 10
Dependent Claim
49 words
A converter system according to claim 5 wherein said control circuits further comprise computation means for producing at least one cyclically varying retard limit control signal having a zero-crossing, and comparing means for generating said firing angle retard limit signal upon the passage through zero of said control signal.
Claim 11
Dependent Claim
33 words
A converter system according to claim 8 wherein said retard limit signal has multiple zero-crossings, and time delay means for inhibiting the generation of spurious retard limit signals subsequent to the initial zero-crossing.
Claim 12
Dependent Claim
265 words
A high frequency link cycloconverter system comprising first and second polyphase cycloconverter power circuits each having in each phase a plurality of thyristors that are rendered conductive in sequence at a variable frequency to produce a desired output, intermediate parallel resonant commutation means connected in a link between said cycloconverter circuits and including commutating inductance means and parallel commutating capacitor means for supplying a variable amount of reactive power to selectively render said thyristors nonconductive, and a firing circuit comprising retard limit signal means for generating a firing angle retard limit signal for each cycloconverter circuit, said retard limit signal means including for each cycloconverter circuit a constant turn-off time control circuit for computing the timiNg of firing signals for each incoming thyristor at the retard limit to provide an approximately constant turn-off time for each corresponding outgoing thyristor, wherein each constant turn-off time control circuit comprises sensing means for sensing the instantaneous voltage of said commutating capacitor means and for sensing selected instantaneous power circuit currents indicative of the commutating capacitor means current after the firing of each cycloconverter thyristor at the retard limit, computation means for producing a cyclically varying retard limit control signal, comparing means for comparing said retard limit control signal with a reference and generating said retard limit signal, and said sensing and computation means are provided by potential and current transformers, each current transformer having an associated burden resistor coupled across its secondary winding which is in turn coupled in series with each potential transformer secondary winding to form an analog circuit for producing said retard limit control signal.
Claim 13
Dependent Claim
265 words
A high frequency link cycloconverter system comprising first and second polyphase cycloconverter power circuits each having in each phase a plurality of thyristors that are rendered conductive in sequence at a variable frequency to produce a desired output, intermediate parallel resonant commutation means connected in a link between said cycloconverter circuits and including commutating inductance means and parallel commutating capacitor means for supplying a variable amount of reactive power to selectively render said thyristors nonconductive, and a firing circuit comprising retard limit signal means for generating a firing angle retard limit signal for each cycloconverter circuit, said retard limit signal means including for each cycloconverter circuit a constant turn-off time control circuit for computing the timiNg of firing signals for each incoming thyristor at the retard limit to provide an approximately constant turn-off time for each corresponding outgoing thyristor, wherein each constant turn-off time control circuit comprises sensing means for sensing the instantaneous voltage of said commutating capacitor means and for sensing selected instantaneous power circuit currents indicative of the commutating capacitor means current after the firing of each cycloconverter thyristor at the retard limit, computation means for producing a cyclically varying retard limit control signal, comparing means for comparing said retard limit control signal with a reference and generating said retard limit signal, and said sensing and computation means are provided by potential and current transformers, each current transformer having an associated burden resistor coupled across its secondary winding which is in turn coupled in series with each potential transformer secondary winding to form an analog circuit for producing said retard limit control signal.
Claim 14
Dependent Claim
41 words
A converter system according to claim 10 wherein at least one potential transformer and at least one current transformer with its associated burden resistor are common to the constant turn-off time control circuits for both the first and second cycloconverter circuits.
Claim 15
Dependent Claim
251 words
A high frequency link cycloconverter system comprising first and second polyphase cycloconverter power circuits each having in each phase a plurality of thyristors that are rendered conductive in sequence at a variable frequency to produce a desired output, intermediate parallel resonant commutation means connected in a link between said cycloconverter circuits and including commutating inductance means and parallel commutating capacitor means for supplying a variable amount of reactive power to selectively render said thyristors nonconductive, and a firing circuit comprising retard limit signal means for generating a firing angle retard limit signal for each cycloconverter circuit, said retard limit signal means including for each cycloconverter circuit a constant turnoff time control circuit for computing the timing of firing signals for each incoming thyristor at the retard limit to provide an approximately constant turn-off time for each corresponding outgoing thyristor, wherein each constant turn-off time control circuit comprises sensing means for sensing the instantaneous voltage of said commutating capacitor means and for sensing a plurality of instantaneous power circuit currents indicative of the commutating capacitor means current after the firing of each incoming thyristor at the retard limit, and said sensing means includes a potential transformer and current transformer for sensing the instantaneous voltage and current of each separate commutating capacitor, and a current transformer in each cycloconverter phase to sense the instantaneous cycloconverter current, the outputs of the respective like transformers being effectively summed in said control circuit to obtain the total commutating capacitor voltage and current and total cycloconverter current.
Claim 16
Dependent Claim
251 words
A high frequency link cycloconverter system comprising first and second polyphase cycloconverter power circuits each having in each phase a plurality of thyristors that are rendered conductive in sequence at a variable frequency to produce a desired output, intermediate parallel resonant commutation means connected in a link between said cycloconverter circuits and including commutating inductance means and parallel commutating capacitor means for supplying a variable amount of reactive power to selectively render said thyristors nonconductive, and a firing circuit comprising retard limit signal means for generating a firing angle retard limit signal for each cycloconverter circuit, said retard limit signal means including for each cycloconverter circuit a constant turnoff time control circuit for computing the timing of firing signals for each incoming thyristor at the retard limit to provide an approximately constant turn-off time for each corresponding outgoing thyristor, wherein each constant turn-off time control circuit comprises sensing means for sensing the instantaneous voltage of said commutating capacitor means and for sensing a plurality of instantaneous power circuit currents indicative of the commutating capacitor means current after the firing of each incoming thyristor at the retard limit, and said sensing means includes a potential transformer and current transformer for sensing the instantaneous voltage and current of each separate commutating capacitor, and a current transformer in each cycloconverter phase to sense the instantaneous cycloconverter current, the outputs of the respective like transformers being effectively summed in said control circuit to obtain the total commutating capacitor voltage and current and total cycloconverter current.
Claim 17
Dependent Claim
47 words
A converter system according to claim 12 wherein each control circuit further includes computation means for producing a cyclically varying retard limit control circuit having a zero-crossing, and comparing means for generating said firing angle retard limit signal upon the passage through zero of said control signal.
Claim 18
Dependent Claim
34 words
A converter system according to claim 13 wherein said retard limit control signal has multiple zero-crossings, and time delay means for inhibiting the generation of spurious retard limit signals subsequent to the initial zero-crossing.
Claim 19
Independent Claim
257 words
The method of producing a firing angle retard limit signal for a high frequency link converter system comprising a first power converter circuit and a second phase controlled converter power circuit each having a plurality of controlled power devices that are rendered coNductive sequentially at a variable frequency to produce a desired output, intermediate parallel resonant commutation circuit means connected in a link between said converter circuits and including commutating inductance means and parallel commutating capacitor means for supplying a variable amount of reactive power to selectively render said controlled power devices nonconductive, and a firing circuit for said converters, said method comprising the steps of sensing selected power circuit parameters from which the future state of said commutating capacitor means can be predicted, computing from the sensed parameters and generating a cyclically varying retard limit signal which comprises as a minimum a constant turn-off time control signal for timing the firing of an incoming first power converter circuit controlled power device that obtains an approximately constant turn-off time for a corresponding outgoing first power converter circuit controlled power device, and deriving from said retard limit control signal a firing angle retard limit signal for the phase controlled converter controlled power devices, wherein said second phase controlled converter is a polyphase cycloconverter, and the computing and generating step further includes computing and generating another component of said retard limit control signal for producing added turn-off time at least sufficient to commutate current from one outgoing cycloconverter controlled power device to another corresponding incoming cycloconverter controlled power device.
Claim 20
Independent Claim
257 words
The method of producing a firing angle retard limit signal for a high frequency link converter system comprising a first power converter circuit and a second phase controlled converter power circuit each having a plurality of controlled power devices that are rendered coNductive sequentially at a variable frequency to produce a desired output, intermediate parallel resonant commutation circuit means connected in a link between said converter circuits and including commutating inductance means and parallel commutating capacitor means for supplying a variable amount of reactive power to selectively render said controlled power devices nonconductive, and a firing circuit for said converters, said method comprising the steps of sensing selected power circuit parameters from which the future state of said commutating capacitor means can be predicted, computing from the sensed parameters and generating a cyclically varying retard limit signal which comprises as a minimum a constant turn-off time control signal for timing the firing of an incoming first power converter circuit controlled power device that obtains an approximately constant turn-off time for a corresponding outgoing first power converter circuit controlled power device, and deriving from said retard limit control signal a firing angle retard limit signal for the phase controlled converter controlled power devices, wherein said second phase controlled converter is a polyphase cycloconverter, and the computing and generating step further includes computing and generating another component of said retard limit control signal for producing added turn-off time at least sufficient to commutate current from one outgoing cycloconverter controlled power device to another corresponding incoming cycloconverter controlled power device.
Claim 21
Dependent Claim
51 words
The method according to claim 15 wherein the sensing step includes sensing the instantaneous cycloconverter current in each phase individually, the computing and generating includes generating a separate retard limit control signal for each phase, and the deriving step includes deriving individual firing angle retard limit signals for each cycloconverter phase.
Claim 22
Dependent Claim
48 words
The method according to claim 15 wherein the sensing step includes sensing the total instantaneous cycloconverter current in all the phases, and the computing and generating step and deriving step includes generating a single retard limit control signal and firing angle retard limit signal for all the phases.
Claim 23
Independent Claim
307 words
The method of producing a firing angle retard limit signal for a high frequency link converter system comprising a first power converter circuit and a second phase controlled converter power circuit each having a plurality of controlled power devices that are rendered conductive sequentially at a variable frequency to produce a desired output, intermediate parallel resonant commutation circuit means connected in a link between said converter circuits and including commutating inductance means and parallel commutating capacitor means for supplying a variable amount of reactive power to selectively render said controlled power devices nonconductive, and a firing circuit for said converters, said method comprising the steps of sensing selected power circuit parameters from which the furture state of said commutating capacitor means can be predicted, computing from the sensed parameters and generating a cyclically varying retard limit signal which comprises as a minimum a constant turn-off time control signal for timing the firing of an incoming controlled power device that obtains an approximately constant turn-off time for a corresponding outgoing controlled power device, and deriving from said retard limit control signal a firing angle retard limit signal for the phase controlled converter controlled power devices, wherein said first and second power converter circuits are both polyphase cycloconverter power circuits, and the sensing step includes sensing the instantaneous, cycloconverter current components in the first and second cycloconverter power circuits and respectively summing the current components to obtain the total instantaneous current in each cycloconverter, the computing and generating step and derIving step include generating separate retard limit control signals and firing angle retard limit signals for the first and second cycloconverter power circuits, and the sensing step further includes sensing the instantaneous commutating capacitor means voltage and current components and respectively summing the last mentioned components to obtain the total instantaneous voltage and current of said commutating capacitor means.
Claim 24
Independent Claim
307 words
The method of producing a firing angle retard limit signal for a high frequency link converter system comprising a first power converter circuit and a second phase controlled converter power circuit each having a plurality of controlled power devices that are rendered conductive sequentially at a variable frequency to produce a desired output, intermediate parallel resonant commutation circuit means connected in a link between said converter circuits and including commutating inductance means and parallel commutating capacitor means for supplying a variable amount of reactive power to selectively render said controlled power devices nonconductive, and a firing circuit for said converters, said method comprising the steps of sensing selected power circuit parameters from which the furture state of said commutating capacitor means can be predicted, computing from the sensed parameters and generating a cyclically varying retard limit signal which comprises as a minimum a constant turn-off time control signal for timing the firing of an incoming controlled power device that obtains an approximately constant turn-off time for a corresponding outgoing controlled power device, and deriving from said retard limit control signal a firing angle retard limit signal for the phase controlled converter controlled power devices, wherein said first and second power converter circuits are both polyphase cycloconverter power circuits, and the sensing step includes sensing the instantaneous, cycloconverter current components in the first and second cycloconverter power circuits and respectively summing the current components to obtain the total instantaneous current in each cycloconverter, the computing and generating step and derIving step include generating separate retard limit control signals and firing angle retard limit signals for the first and second cycloconverter power circuits, and the sensing step further includes sensing the instantaneous commutating capacitor means voltage and current components and respectively summing the last mentioned components to obtain the total instantaneous voltage and current of said commutating capacitor means.
Claim 25
Dependent Claim
42 words
The method according to claim 18 wherein the deriving step includes comparing said cyclically varying retard limit control signal to a zero voltage reference, and generating said firing angle retard limit signal at the initial zero-crossing of said retard limit control signal.
Claim 26
Dependent Claim
31 words
The method according to claim 19 wherein the driving step further includes inhibiting the generation of spurious firing angle retard limit signals at subsequent zero-crossings of said retard limit control signal.
References Cited (Backward Citations)
US3448368A
Cited
US3319147A
Cited
US3466525A
Cited
US3566148A
Cited
US3718852A
Cited
US3742336A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-05 | 1978-11-04 | 1979-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-05 | 1982-11-04 | 1983-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-05 | 1986-11-04 | 1987-05-06 | $7700.00 | Window Closed / Lapsed |