Patent US4728806A successfully refreshed from Google Patents.
US4728806A
Expired / Lapsed
US
⏱️ 0.0 years remaining
DC link variable speed constant frequency power source paralleling controls
Assignee: Sundstrand Corp
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Filing: 1986-12-05
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Granted: 1988-03-01
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Expires: 2006-12-05
Abstract
Abstract A parallel power system includes at least two DC link variable speed constant frequency power sources each having a plurality of output phases connected to a common bus. The total real error current flowing in the output phases of each of the power sources is monitored and the relative phase angle of the Thevenin voltage of the power sources is controlled in response to the monitored total real error current to reduce the magnitude of this real error current. The reactive error current flowing in at least one of the output phases of each of the power sources is monitored and the relative magnitude of the Thevenin voltage of the power sources is controlled in response to the monitored reactive error current to reduce the magnitude of the reactive error current. For operation at no load, the phase angle control loop is sensitive to both real and reactive error currents.
Inventors
- 👤 Donal E. Baker
- 👤 Mirza A. Beg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 10:01
CPC Classifications
H; H02; H02M; H02M5/00; H02M5/40; H02M5/42; H02M5/44; H02M5/453; H02M5/458
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
144 words
A parallel power system comprising: at least two DC link variable speed, constant frequency power sources each having a Thevenin voltage and a plurality of output phases connected to a multiple phase common bus; said power sources having substantially the same output frequency; means for monitoring total real error current flowing in said output phases of each of said power sources; means for controlling the relative phase angle of the Thevenin voltages of said power sources in response to said total real error current, to reduce the magnitude of said real error current; means for monitoring reactive error current flowing in at least one of said output phases of each of said power sources; means for controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error current, to reduce the magnitude of said reactive error current.
Claim 2
Dependent Claim
144 words
A parallel power system comprising: at least two DC link variable speed, constant frequency power sources each having a Thevenin voltage and a plurality of output phases connected to a multiple phase common bus; said power sources having substantially the same output frequency; means for monitoring total real error current flowing in said output phases of each of said power sources; means for controlling the relative phase angle of the Thevenin voltages of said power sources in response to said total real error current, to reduce the magnitude of said real error current; means for monitoring reactive error current flowing in at least one of said output phases of each of said power sources; means for controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error current, to reduce the magnitude of said reactive error current.
Claim 3
Dependent Claim
31 words
A parallel power system as recited in claim 1, further comprising: a plurality of filter inductors, one of said inductors being electrically connected in series with each of said output phases.
Claim 4
Dependent Claim
71 words
A parallel power system as recited in claim 1, wherein said means for monitoring error current comprises: a plurality of current transformers, each of said transformers being inductively coupled to one of said output phases; said transformers which are coupled to connected ones of said output phases, being electrically connected in series with each other; and each of said transformers being electrically connected in parallel with a capacitor and a resistor.
Claim 5
Dependent Claim
68 words
A parallel power system as recited in claim 1, wherein each of said power sources comprises: a variable speed generator; a pair of DC link conductors: means for rectifying the output of said generator to place a DC voltage on said DC link conductors; and means for switching voltage from said DC link conductors to each of said output phases, to produce AC voltages on said output phases.
Claim 6
Dependent Claim
100 words
A parallel power system as recited in claim 4, wherein said means for controlling the relative phase angle of the Thevenin voltage comprises: a waveform pattern generator for controlling the operation of said switching means and for producing a first signal representative of the phase angle of the Thevenin voltage of one of said power sources; and means for combining said first signal with a real error current signal and a clock signal to produce a phase angle control signal; said waveform pattern generator being responsive to said phase angle control signal to modify the operation of said switching means.
Claim 7
Dependent Claim
77 words
A parallel power system as recited in claim 4, wherein said means for controlling the relative magnitude of the Thevenin voltages comprises: means for producing an output voltage magnitude signal, representative of the output voltage of one of said power sources; means for combining said output voltage magnitude signal with a reactive error current signal, to produce a generator control signal; and means for varying the output of said generator in response to said generator control signal.
Claim 8
Dependent Claim
144 words
A parallel power system comprising: at least two DC link variable speed, constant frequency power sources each having a Thevenin voltage and N output phases connected to a common bus; said power sources having substantially the same output frequency; means for monitoring error current flowing in at least N-1 of said output phases of each of said power sources; means for demodulating said error current to derive a real error current component and a reactive error current component; means for controlling the relative phase angle of the Thevenin voltages of said power sources in response to said real error current component, to reduce the magnitude of said real error current component; and means for controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error current component, to reduce the magnitude of said reactive error current component.
Claim 9
Dependent Claim
144 words
A parallel power system comprising: at least two DC link variable speed, constant frequency power sources each having a Thevenin voltage and N output phases connected to a common bus; said power sources having substantially the same output frequency; means for monitoring error current flowing in at least N-1 of said output phases of each of said power sources; means for demodulating said error current to derive a real error current component and a reactive error current component; means for controlling the relative phase angle of the Thevenin voltages of said power sources in response to said real error current component, to reduce the magnitude of said real error current component; and means for controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error current component, to reduce the magnitude of said reactive error current component.
Claim 10
Dependent Claim
31 words
A parallel power system as recited in claim 7, further comprising: a plurality of filter inductors, one of said inductors being electrically connected in series with each of said output phases.
Claim 11
Dependent Claim
68 words
A parallel power system as recited in claim 7, wherein said means for monitoring error current comprises: a plurality of current transformers, each of said transformers being inductively coupled to one of said output phases; said transformers which are coupled to said output phases, being electrically connected in series with each other; and each of said transformers being electrically connected in parallel with a capacitor and a resistor.
Claim 12
Dependent Claim
68 words
A parallel power system as recited in claim 7, wherein each of said power sources comprises: a variable speed generator; a pair of DC link conductors; means for rectifying the output of said generator to place a DC voltage on said DC link conductors; and means for switching voltage from said DC link conductors to each of said output phases, to produce AC voltages on said output phases.
Claim 13
Dependent Claim
100 words
A parallel power system as recited in claim 10, wherein said means for controlling the relative phase angle of the Thevenin voltages comprises: a waveform pattern generator for controlling the operation of said switching means and for producing a first signal representative of the phase angle of the Thevenin voltage of one of said power sources; and means for combining said first signal with said real error current component and a clock signal to produce a phase angle control signal; said waveform pattern generator being responsive to said phase angle control signal to modify the operation of said switching means.
Claim 14
Dependent Claim
77 words
A parallel power system as recited in claim 10, wherein said means for controlling the relative magnitude of the Thevenin voltages comprises: means for producing an output voltage magnitude signal, representative of the output voltage of one of said power sources; means for combining said output voltage magnitude signal with said reactive error current component, to produce a generator control signal; and means for varying the output of said generator in response to said generator control signal.
Claim 15
Independent Claim
133 words
A method of controlling parallel connected DC link, variable speed, constant frequency multiple phase power sources, said method comprising the steps of: monitoring total real error current flowing in a plurality of output conductors of at least two, parallel connected constant frequency power sources, each having a Thevenin voltage; controlling the relative phase angle of the Thevenin voltages of said power sources in response to said total real error current, to reduce the magnitude of said total real error current; monitoring the reactive error current flowing in at least one of the output conductors of each of said parallel connected constant frequency power sources; and controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error current, to reduce the magnitude of said reactive error current.
Claim 16
Independent Claim
133 words
A method of controlling parallel connected DC link, variable speed, constant frequency multiple phase power sources, said method comprising the steps of: monitoring total real error current flowing in a plurality of output conductors of at least two, parallel connected constant frequency power sources, each having a Thevenin voltage; controlling the relative phase angle of the Thevenin voltages of said power sources in response to said total real error current, to reduce the magnitude of said total real error current; monitoring the reactive error current flowing in at least one of the output conductors of each of said parallel connected constant frequency power sources; and controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error current, to reduce the magnitude of said reactive error current.
Claim 17
Independent Claim
124 words
A method of controlling parallel connected DC link, variable speed, constant frequency N-phase power sources, said method comprising the steps of: monitoring error current flowing in at least N-1 output conductors of at least two, parallel connected constant frequency power sources, each having a Thevenin voltage; demodulating said error current to derive a total real error current component and a reactive error current component; controlling the relative phase angle of the Thevenin voltages of said power sources in response to said total real error current component, to reduce the magnitude of said real error component; and controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error component, to reduce the magnitude of said reactive error component.
Claim 18
Independent Claim
124 words
A method of controlling parallel connected DC link, variable speed, constant frequency N-phase power sources, said method comprising the steps of: monitoring error current flowing in at least N-1 output conductors of at least two, parallel connected constant frequency power sources, each having a Thevenin voltage; demodulating said error current to derive a total real error current component and a reactive error current component; controlling the relative phase angle of the Thevenin voltages of said power sources in response to said total real error current component, to reduce the magnitude of said real error component; and controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error component, to reduce the magnitude of said reactive error component.
Claim 19
Dependent Claim
133 words
A parallel power system comprising: at least two DC link, variable speed, constant frequency power sources each having a Thevenin voltage and a plurality of output phases connected to a common bus; said power sources having substantially the same output frequency; means for monitoring total real error current flowing in said output phases of each of said power sources; means for monitoring reactive error current flowing in at least one of said output phases of each of said power sources; means for controlling the relative phase angle of the Thevenin voltages of said power sources in response to a combination of said total real error current and said reactive error current; and means for controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error current.
Claim 20
Dependent Claim
133 words
A parallel power system comprising: at least two DC link, variable speed, constant frequency power sources each having a Thevenin voltage and a plurality of output phases connected to a common bus; said power sources having substantially the same output frequency; means for monitoring total real error current flowing in said output phases of each of said power sources; means for monitoring reactive error current flowing in at least one of said output phases of each of said power sources; means for controlling the relative phase angle of the Thevenin voltages of said power sources in response to a combination of said total real error current and said reactive error current; and means for controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error current.
Claim 21
Dependent Claim
31 words
A parallel power system as recited in claim 15, further comprising: a plurality of filter inductors, one of said inductors being electrically connected in series with each of said output phases.
Claim 22
Dependent Claim
71 words
A parallel power system as recited in claim 15, wherein said means for monitoring error current comprises: a plurality of current transformers, each of said transformers being inductively coupled to one of said output phases; said transformers which are coupled to connected ones of said output phases, being electrically connected in series with each other; and each of said transformers being electrically connected in parallel with a capacitor and a resistor.
Claim 23
Dependent Claim
68 words
A parallel power system as recited in claim 15, wherein each of said power sources comprises: a variable speed generator; a pair of DC link conductors; means for rectifying the output of said generator to place a DC voltage on said DC link conductors; and means for switching voltage from said DC link conductors to each of said output phases, to produce AC voltages on said output phases.
Claim 24
Dependent Claim
126 words
A parallel power system as recited in claim 18, wherein said means for controlling the relative phase angle of the Thevenin voltages comprises: a waveform pattern generator for controlling the operation of said switching means and for producing a first signal representative of the phase angle of the Thevenin voltage of one of said power sources; means for combining said first signal with a combination error current signal and a clock signal to produce a phase angle control signal, said error current signal being representative of both said real error current signal being representative of both said real error current and said reactive error current; and said waveform pattern generator being responsive to said phase angle control signal to modify the operation of said switching means.
Claim 25
Dependent Claim
77 words
A parallel power system as recited in claim 18, wherein said means for controlling the relative magnitude of the Thevenin voltages comprises: means for producing an output voltage magnitude signal, representative of the output voltage of one of said power sources; means for combining said output voltage magnitude signal with a reactive error current signal, to produce a generator control signal; and means for varying the output of said generator in response to said generator control signal.
Claim 26
Dependent Claim
133 words
A parallel power system comprising; at least two DC link variable speed, constant frequency power sources each having a Thevenin voltage and N output phases connected to a common bus; said power sources having substantially the same output frequency; means for monitoring error current flowing in at least N-1 of said output phases of each of said power sources; means for demodulating said error current to derive a real error current component and a reactive error current component; means for controlling the relative phase angle of the Thevenin voltages of said power sources in response to a combination of said real error current component and said reactive error current component; and means for controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error current component.
Claim 27
Dependent Claim
133 words
A parallel power system comprising; at least two DC link variable speed, constant frequency power sources each having a Thevenin voltage and N output phases connected to a common bus; said power sources having substantially the same output frequency; means for monitoring error current flowing in at least N-1 of said output phases of each of said power sources; means for demodulating said error current to derive a real error current component and a reactive error current component; means for controlling the relative phase angle of the Thevenin voltages of said power sources in response to a combination of said real error current component and said reactive error current component; and means for controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error current component.
Claim 28
Dependent Claim
31 words
A parallel power system as recited in claim 21, further comprising: a plurality of filter inductors, one of said inductors being electrically connected in series with each of said output phases.
Claim 29
Dependent Claim
71 words
A parallel power system as recited in claim 21, wherein said means for monitoring error current comprises: a plurality of current transformers, each of said transformers being inductively coupled to one of said output phases; said transformers which are coupled to connected ones of said output phases, being electrically connected in series with each other; and each of said transformers being electrically connected in parallel with a capacitor and a resistor.
Claim 30
Dependent Claim
68 words
A parallel power system as recited in claim 21, wherein each of said power sources comprises: a variable speed generator; a pair of DC link conductors; means for rectifying the output of said generator to place a DC voltage on said DC link conductors; and means for switching voltage from said DC link conductors to each of said output phases, to produce AC voltages on said output phases.
Claim 31
Dependent Claim
108 words
A parallel power system as recited in claim 24, wherein said means for controlling the relative phase angle of the Thevenin voltages comprises: a waveform pattern generator for controlling the operation of said switching means and for producing a first signal representative of the phase angle of the Thevenin voltage of one of the power sources; means for combining said first signal with a combination of said real error current component, said reactive error current component and a clock signal to produce a phase angle control signal; and said waveform pattern generator being responsive to said phase angle control signal to modify the operation of said switching means.
Claim 32
Dependent Claim
77 words
A parallel power system as recited in claim 24, wherein said means for controlling the relative magnitude of the Thevenin voltages comprises; means for producing an output voltage magnitude signal, representative of the output voltage of one of said power sources; means for combining said output voltage magnitude signal with said reactive error current component, to produce a generator control signal; and means for varying the output of said generator in response to said generator control signal.
Claim 33
Independent Claim
122 words
A method of controlling parallel connected DC link, variable speed, constant frequency multiple phase power sources, said method comprising the steps of: monitoring total real error current flowing in a plurality of output conductors of at least two, parallel connected constant frequency power sources, each having a Thevenin voltage; monitoring the reactive error current flowing in at least one of the output conductors of each of said parallel connected constant frequency power sources; controlling the relative phase angle of the Thevenin voltages of said power sources in response to a combination of said total real error current and said reactive error current; and controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error current.
Claim 34
Independent Claim
122 words
A method of controlling parallel connected DC link, variable speed, constant frequency multiple phase power sources, said method comprising the steps of: monitoring total real error current flowing in a plurality of output conductors of at least two, parallel connected constant frequency power sources, each having a Thevenin voltage; monitoring the reactive error current flowing in at least one of the output conductors of each of said parallel connected constant frequency power sources; controlling the relative phase angle of the Thevenin voltages of said power sources in response to a combination of said total real error current and said reactive error current; and controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error current.
Claim 35
Independent Claim
124 words
A method of controlling parallel connected DC link, variable speed, constant frequency N-phase power sources, said method comprising the steps of; monitoring error current flowing in at least N-1 output conductors of at least two, parallel connected constant frequency power sources, each having a Thevenin voltage; demodulating said error current to derive a total real error current component and a reactive error current component; controlling the relative phase angle of the Thevenin voltages of said power sources in response to a combination of said total real error current component and said reactive error current component; and controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error component, to reduce the magnitude of said reactive error component.
Claim 36
Independent Claim
124 words
A method of controlling parallel connected DC link, variable speed, constant frequency N-phase power sources, said method comprising the steps of; monitoring error current flowing in at least N-1 output conductors of at least two, parallel connected constant frequency power sources, each having a Thevenin voltage; demodulating said error current to derive a total real error current component and a reactive error current component; controlling the relative phase angle of the Thevenin voltages of said power sources in response to a combination of said total real error current component and said reactive error current component; and controlling the relative magnitude of the Thevenin voltages of said power sources in response to said reactive error component, to reduce the magnitude of said reactive error component.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1991-03-01 | 1991-08-31 | 1992-03-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-01 | 1995-08-31 | 1996-03-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-01 | 1999-08-31 | 2000-03-01 | $7700.00 | Window Closed / Lapsed |