US4545002A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thyristor voltage limiter for current source inverter
Assignee: General Electric Co
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Filing: 1983-06-28
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Granted: 1985-10-01
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Expires: 2003-06-28
Abstract
Abstract A voltage limiter for protecting the thyristors of a current source inverter, also known as a controlled current inverter, wherein the limiter includes a circuit for sensing the respective voltages directly across at least one but preferably across each of the thyristors in the inverter and generating a signal corresponding to the highest value and a regulator circuit which is operable in response to the difference between the highest value signal and a reference signal corresponding to a safe operating voltage for the thyristors in the inverter, to modify the thyristor gating angle of those thyristors which control the current in the inverter. The voltage limiter thus reduces the current carried by the inverter thyristors when the highest voltage across the inverter thyristors exceeds the reference signal, and thereby reduces the amplitude of any commutating spike voltage in the voltage applied across the thyristors. This permits full utilization of the inverter rating while requiring no adjustment for source impedance, line voltage, or commutating capacitance.
Inventors
- 👤 Loren H. Walker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:03
CPC Classifications
H; H02; H02M; H02M5/00; H02M5/40; H02M5/42; H02M5/44; H02M5/443; H02M5/45; H02M5/4505
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
126 words
A control circuit for protecting the controlled rectifiers of an electrical power inverter comprising: (a) a force commutated current source inverter including a plurality of controlled rectifier devices having first and second power electrodes; (b) means for sensing the voltage across the first and second power electrodes of at least one of said controlled rectifier devices; (c) means for comparing the sensed voltage across said first and second power electrodes against a reference voltage corresponding to a signal proportional to a safe operating voltage for said controlled rectifier devices and generating a control signal therefrom; and (d) means responsive to said control signal for controlling the current within said inverter to thereby prevent an increase in the voltage across said power electrodes above said reference voltage.
Claim 2
Dependent Claim
126 words
A control circuit for protecting the controlled rectifiers of an electrical power inverter comprising: (a) a force commutated current source inverter including a plurality of controlled rectifier devices having first and second power electrodes; (b) means for sensing the voltage across the first and second power electrodes of at least one of said controlled rectifier devices; (c) means for comparing the sensed voltage across said first and second power electrodes against a reference voltage corresponding to a signal proportional to a safe operating voltage for said controlled rectifier devices and generating a control signal therefrom; and (d) means responsive to said control signal for controlling the current within said inverter to thereby prevent an increase in the voltage across said power electrodes above said reference voltage.
Claim 3
Dependent Claim
36 words
The control circuit of claim 1 wherein said plurality of controlled rectifier devices comprise a plurality of thyristors, and wherein said means (b) for sensing comprises means for sensing the voltage across each of said thyristors.
Claim 4
Dependent Claim
63 words
The control circuit of claim 1 wherein said plurality of controlled rectifier devices comprise a plurality of thyristors, wherein said means (b) for sensing comprises means for sensing the highest voltage across each of said thyristors, and wherein said means (c) for comparing comprises means for comparing said highest voltage against said reference voltage and generating a control signal comprising the difference therebetween.
Claim 5
Dependent Claim
30 words
The control circuit of claim 3 wherein said current source inverter comprises a DC to AC power inverter coupled to a motor load and operating to drive said motor load.
Claim 6
Dependent Claim
69 words
The control circuit of claim 4 and wherein said means (d) for controlling current comprises: (i) an AC to DC power converter coupled to and supplying current to said inverter by a DC link circuit, and (ii) means responsive to said control signal for controlling said power converter to vary the current supplied to said inverter in accordance with the difference between said highest voltage and said reference voltage.
Claim 7
Dependent Claim
44 words
The control circuit of claim 5 wherein said power converter includes a plurality of controlled rectifier devices coupled to an alternating current source and wherein said means (ii) for controlling said power converter comprises means for controlling the firing angle of said controlled rectifiers.
Claim 8
Dependent Claim
22 words
The control circuit of claim 6 wherein said plurality of controlled rectifier devices of said power converter comprise a plurality of thyristors.
Claim 9
Dependent Claim
32 words
The control circuit of claim 3 wherein said current source inverter (a) comprises an inductively loaded thyristor inverter coupled to an alternating current source and operating as a current source var generator.
Claim 10
Dependent Claim
30 words
The control circuit of claim 8, and wherein said means (d) for controlling current comprises means for controlling the firing angle of said thyristors of said inverter for controlling vars.
Claim 11
Dependent Claim
73 words
The control circuit of claim 3 wherein said thyristors include anode and cathode electrodes and said means (b) for sensing the highest voltage across each of said thyristors comprises: (i) means for providing respective difference signals proportional to the voltage across the anode and cathode electrodes of each of said thyristors, and (ii) means for combining said difference signals at a common circuit node to provide a signal proportional to said highest voltage.
Claim 12
Dependent Claim
26 words
The control circuit of claim 10 and further comprising: (iii) rectifier means connected between said means for providing respective difference signals and said common circuit node.
Claim 13
Dependent Claim
56 words
The control circuit of claim 11 wherein said means (i) for providing respective difference signals comprises a respective differential amplifier having first and second input terminals coupled across one thyristor of said plurality of thyristors, and wherein said rectifier means (iii) comprises a respective half-wave rectifier connected between each differential amplifier and said common circuit node.
Claim 14
Dependent Claim
30 words
The control circuit of claim 3 and wherein said means (d) for controlling current additionally includes regulator circuit means for limiting the current in said inverter to a predetermined limit.
Claim 15
Dependent Claim
21 words
The control circuit of claim 13 wherein regulator circuit means comprises an operational amplifier having a predetermined controller type transfer function.
Claim 16
Dependent Claim
186 words
The control circuit of claim 3 wherein said current source inverter (a) comprises a DC to AC power inverter coupled to a motor load and operating to drive said motor load, wherein said means (d) for controlling current includes an AC to DC power converter coupled to and supplying current to said inverter by way of a DC link, and means responsive to said control signal for controlling said power converter to vary the current supplied to said inverter in accordance with said control signal, wherein said thyristors of said inverter include anode and cathode electrodes and said means for sensing the highest voltage across each of said thyristors of said inverter includes means for providing respective difference signals proportional to the voltages across the anode and cathode electrodes of said thyristors and means for combining said difference signals at a common circuit node to provide a signal proportional to said highest voltage, and wherein said means (d) for controlling current additionally includes regulator circuit means coupled to said signal proportional to said highest voltage for limiting the current in said inverter to a predetermined limit.
Claim 17
Dependent Claim
49 words
The control circuit of claim 15 wherein said power converter includes a plurality of thyristors coupled to an alternating current source and wherein said means for controlling said power converter comprises means for controlling the firing angle of the thyristors of said converter in response to said control signal.
Claim 18
Dependent Claim
88 words
The control circuit of claim 16 wherein said means for controlling the firing angle of the thyristors of said converter additionally comprise: (i) a thyristor firing circuit for firing the converter thyristors at a predetermined firing angle; (ii) means including another regulator circuit means for controlling the firing angle of the thyristor firing circuit in response to a current command signal; and (iii) means coupling said current command signal and said control signal to said thyristor firing circuit whereby both said signals operate to control said firing angle.
Claim 19
Dependent Claim
54 words
The control circuit of claim 17 wherein said coupling means (iii) comprises a diode takeover circuit respectively coupled between both said regulator circuit means and said thyristor firing circuit for controlling thyristor firing angle in response to which of said current command signal and said control signal calls for the latest thyristor firing angle.
Claim 20
Dependent Claim
151 words
The control circuit of claim 3 wherein said current source inverter (a) comprises an inductively loaded force commutated thyristor inverter coupled to an alternating current source and operating as a current source var generator, wherein said thyristors include anode and cathode electrodes and said means (b) for sensing the highest voltage across each of said thyristors of said inverter includes means for providing respective difference signals proportional to the voltage across the anode and cathode electrodes of each of said thyristors and means for combining said difference signals at a common circuit node to provide a signal proportional to said highest voltage, wherein said means (d) for controlling current additionally includes regulator means and means for controlling the firing angle of said thyristors coupled to and being responsive to said control signal, for limiting the current in said inverter to a predetermined limit by controlling the firing angle of said thyristors.
Claim 21
Dependent Claim
82 words
The control circuit of claim 19 wherein said means for controlling the firing angle of said thyristors comprises a thyristor firing circuit for firing the inverter thyristors at a predetermined firing angle, and wherein said means (d) additionally includes means providing a var command signal, another regulator circuit means for controlling the firing angle of the thyristor firing circuit in response to said var command signal, and means coupling said var command signal and said control signal to said thyristor firing circuit.
Claim 22
Dependent Claim
56 words
The control circuit of claim 20 wherein said coupling means comprises a diode takeover circuit respectively coupled between both said regulator circuit means and said thyristor firing circuit for controlling thyristor firing angle of said inverter in response to which of said var command signal and said control signal calls for the earliest thyristor firing angle.
Claim 23
Independent Claim
113 words
A method for protecting the controlled rectifiers of a force commutated current source inverter including a plurality of controlled rectifier devices and comprising the steps of: (a) sensing the voltage across first and second power electrodes of at least one of said plurality of controlled rectifier devices; (b) comparing the sensed voltage across said first and second power electrodes against a reference voltage corresponding to a signal proportional to a safe operating voltage for said controlled rectifier devices and generating a control signal therefrom; and (c) controlling the current within said inverter in response to said control signal to prevent an increase in the voltage across said power electrodes above said reference voltage.
Claim 24
Independent Claim
113 words
A method for protecting the controlled rectifiers of a force commutated current source inverter including a plurality of controlled rectifier devices and comprising the steps of: (a) sensing the voltage across first and second power electrodes of at least one of said plurality of controlled rectifier devices; (b) comparing the sensed voltage across said first and second power electrodes against a reference voltage corresponding to a signal proportional to a safe operating voltage for said controlled rectifier devices and generating a control signal therefrom; and (c) controlling the current within said inverter in response to said control signal to prevent an increase in the voltage across said power electrodes above said reference voltage.
Claim 25
Dependent Claim
35 words
The method of claim 22 wherein said plurality of controlled rectifier devices comprise a plurality of thyristors, and wherein said sensing step (a) comprises the step of sensing the voltages across each of said thyristors.
Claim 26
Dependent Claim
64 words
The method of claim 22 wherein said plurality of controlled rectifier devices comprise a plurality of thyristors, wherein said step (a) of sensing comprises the steps of sensing the highest voltage across each of said thyristors, and wherein said step (b) of comparing comprises the step of comparing said highest voltage against said reference voltage and generating a control signal comprising the difference therebetween.
Claim 27
Dependent Claim
68 words
The method of claim 24 wherein said current source inverter comprises a DC to AC power inverter coupled to an AC to DC power converter by means of a DC link and operating to drive a motor load and wherein said step (c) of controlling current comprises the step of controlling said power converter to vary the current supplied to said inverter in accordance with said control signal.
Claim 28
Dependent Claim
44 words
The method of claim 25 wherein said power converter includes a plurality of thyristors coupled to an alternating current source and wherein said step of controlling said power converter comprises the step of controlling the firing angle of said thyristors of said power converter.
Claim 29
Dependent Claim
56 words
The method of claim 24 wherein said current source inverter comprises an inductively loaded force commutated thyristor inverter coupled to an alternating current source and operating as a current source var generator, and wherein step (c) for controlling current comprises the step of controlling the firing angle of said thyristors of said inverter for controlling vars.
Claim 30
Dependent Claim
70 words
The method of claim 24 wherein said thyristors include anode and cathode electrodes and said step (b) of sensing the highest voltage across each of said thyristors comprises the steps of providing respective difference signals proportional to the voltage across the anode and cathode electrodes of each of said thyristors and combining said respective difference signals at a common circuit node to provide a signal proportional to said highest voltage.
Claim 31
Dependent Claim
30 words
The method of claim 28 wherein said combining step additionally comprises the steps of rectifying said respective difference signals and coupling the respective rectified signals to said common circuit node.
Claim 32
Dependent Claim
17 words
The method of claim 29 wherein said step of rectifying comprises half-wave rectifying said respective difference signals.
Claim 33
Dependent Claim
32 words
The method of claim 29 and wherein said step (c) of controlling current additionally includes the step of regulating the current in said inverter and limiting said current to a predetermined value.
Claim 34
Dependent Claim
55 words
The method of claim 26 wherein said step of controlling the firing angle of the thyristors of said converter additionally includes the step of controlling the firing angle of said thyristors in response to a current command signal, and controlling said firing angle in response to both said current command signal and said control signal.
Claim 35
Dependent Claim
33 words
The method of claim 32 and additionally including the step of controlling thyristor firing angle in response to the current command signal and the control signal calling for the latest thyristor firing angle.
Claim 36
Dependent Claim
55 words
The method of claim 27 wherein said step of controlling the firing angle of the thyristors of said inverter additionally includes the step of controlling the firing angle of said thyristors in response to a var command signal, and controlling said firing angle in response to both said var command signal and said difference signal.
Claim 37
Dependent Claim
34 words
The method of claim 34 and additionally including the step of controlling thyristor firing angle in response to which of said var command signal and control signal calls for the earliest thyristor firing angle.
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) | 1988-09-30 | 1989-04-01 | 1989-10-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-09-30 | 1993-04-01 | 1993-10-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-09-30 | 1997-04-01 | 1997-10-01 | $7700.00 | Window Closed / Lapsed |