US5349522A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for controlling the output voltage of an AC electrical system
Assignee: Hitachi Ltd
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Filing: 1992-06-12
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Granted: 1994-09-20
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Expires: 2012-06-12
Abstract
Abstract An AC system having, for example, a voltage source, an inductance and a load has connected thereto an apparatus for controlling the phase and amplitude of the voltage of the system. The instantaneous current and voltage in the AC electrical system are measured and power measurements derived therefrom. The power measurements may be instantaneous real and imaginary power, instantaneous active and reactive power, or active and reactive power averaged over less than one cycle. The power measurements are then used to derive phase related control values, on the basis of which control signals are generated to a converter. The action of the converter in accordance with the control signals thus controls the amplitude and phase of the voltage. By use of power measurements, it is not necessary to measure the phase of the voltage of the AC system.
Inventors
- 👤 Hiroo Konishi
- 👤 Hironari Kawazoe
- 👤 Junzo Kawakami
- 👤 Tomoharu Nakamura
- 👤 Yukio Tokiwa
- 👤 Tatsuhito Nakajima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 09:13
CPC Classifications
H; H02; H02J; H02J3/00; H02J3/18; H02J3/1821; H02J3/1835; H02J3/1842; H02M; H02M7/00; H02M7/02; H02M7/04; H02M7/12; H02M7/21; H02M7/217; Y; Y02; Y02E; Y02E40/00; Y02E40/20
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
165 words
A method of controlling the amplitude and phase of the voltage of an AC electrical system, said AC electrical system having a converter, said method comprising: measuring instantaneous current and voltage magnitude values in said AC electrical system; deriving power measurements from said instantaneous current and voltage magnitude values, said power measurements relating to less than one cycle of said AC electrical system, wherein said power measurements are an instantaneous real power and an instantaneous imaginary power; deriving, from said power measurements, phase-related control values, wherein said phase-related control values are a phase-related real current control value obtained from the instantaneous real power divided by the instantaneous voltage magnitude and a phase-related imaginary current control value obtained from the instantaneous imaginary power divided by the instantaneous voltage magnitude; generating control signals for said converter from said phase-related control values; and controlling said converter on the basis of said control signals, thereby to control said amplitude and phase of said voltage of said AC electrical system.
Claim 2
Independent Claim
165 words
A method of controlling the amplitude and phase of the voltage of an AC electrical system, said AC electrical system having a converter, said method comprising: measuring instantaneous current and voltage magnitude values in said AC electrical system; deriving power measurements from said instantaneous current and voltage magnitude values, said power measurements relating to less than one cycle of said AC electrical system, wherein said power measurements are an instantaneous real power and an instantaneous imaginary power; deriving, from said power measurements, phase-related control values, wherein said phase-related control values are a phase-related real current control value obtained from the instantaneous real power divided by the instantaneous voltage magnitude and a phase-related imaginary current control value obtained from the instantaneous imaginary power divided by the instantaneous voltage magnitude; generating control signals for said converter from said phase-related control values; and controlling said converter on the basis of said control signals, thereby to control said amplitude and phase of said voltage of said AC electrical system.
Claim 3
Dependent Claim
45 words
A method according to claim 1, wherein said control signals include an amplitude control signal, which amplitude control signal is proportional to the square root of the sum of the squares of said phase-related real current control value and said phase-related imaginary current control value.
Claim 4
Dependent Claim
43 words
A method according to claim 1, wherein said control signals include a phase control signal, which phase control signal is proportional to the arc tangent of the ratio of said phase-related real current control value and said phase related imaginary current control value.
Claim 5
Dependent Claim
20 words
A method according to claim 1, wherein said power measurements include an instantaneous active power and an instantaneous reactive power.
Claim 6
Dependent Claim
21 words
A method according to claim 1 wherein said power measurements include active and reactive power averaged over less than one cycle.
Claim 7
Dependent Claim
162 words
A control device for controlling the amplitude and phase of the voltage of an AC electric system, said device comprising: a converter for said AC electrical system; means for detecting instantaneous current and voltage magnitude values in said AC electrical system; means for deriving power measurements from said instantaneous current and voltage values, said power measurements relating to less than one cycle of said AC electrical system; means for deriving phase-related control values from said power measurements, wherein said power measurements are an instantaneous real power and an instantaneous imaginary power and said phase-related control values are a phase-related real current control value obtained from the instantaneous real power divided by the instantaneous voltage magnitude and a phase-related imaginary current control value obtained from the instantaneous imaginary power divided by the instantaneous voltage magnitude; a controller for controlling said converter on the basis of said control signals, thereby to control the amplitude and phase of said voltage of said AC electrical system.
Claim 8
Dependent Claim
162 words
A control device for controlling the amplitude and phase of the voltage of an AC electric system, said device comprising: a converter for said AC electrical system; means for detecting instantaneous current and voltage magnitude values in said AC electrical system; means for deriving power measurements from said instantaneous current and voltage values, said power measurements relating to less than one cycle of said AC electrical system; means for deriving phase-related control values from said power measurements, wherein said power measurements are an instantaneous real power and an instantaneous imaginary power and said phase-related control values are a phase-related real current control value obtained from the instantaneous real power divided by the instantaneous voltage magnitude and a phase-related imaginary current control value obtained from the instantaneous imaginary power divided by the instantaneous voltage magnitude; a controller for controlling said converter on the basis of said control signals, thereby to control the amplitude and phase of said voltage of said AC electrical system.
Claim 9
Dependent Claim
13 words
A control device according to claim 6, wherein said converter is an inverter.
Claim 10
Dependent Claim
30 words
A control device according to claim 6, wherein said means for deriving power measurements includes means for deriving an instantaneous active power and means for deriving an instantaneous reactive power.
Claim 11
Dependent Claim
50 words
A control device according to claim 6, wherein said means for deriving power measurements includes means for deriving an active power arranged over less than one cycle of said AC electrical system and means for deriving an reactive power averaged over less than one cycle of said AC electrical system.
Claim 12
Dependent Claim
186 words
An AC electrical system in which the amplitude and phase of the voltage thereof is controllable, said system comprising means for generating an AC signal, and a device for modifying said AC signal, thereby to control said voltage; wherein said device comprises: a converter connectable to said AC electrical system; means for detecting instantaneous current and voltage magnitude values in said AC electrical system; means for deriving power measurements from sid instantaneous current and voltage values, said power measurements relating to less than one cycle of said AC electrical signal, wherein said power measurements are an instantaneous real power and an instantaneous imaginary power; means for deriving phase-related control values from said power measurements, wherein said phase-related control values are a phase-related real current control value obtained from the instantaneous real power divided by the instantaneous voltage magnitude and a phase-related imaginary current control value obtained from the instantaneous imaginary power divided by the instantaneous voltage magnitude; and a controller for controlling said converter on the basis of said control values, thereby to control the amplitude and phase of said voltage of said AC electrical system.
Claim 13
Dependent Claim
186 words
An AC electrical system in which the amplitude and phase of the voltage thereof is controllable, said system comprising means for generating an AC signal, and a device for modifying said AC signal, thereby to control said voltage; wherein said device comprises: a converter connectable to said AC electrical system; means for detecting instantaneous current and voltage magnitude values in said AC electrical system; means for deriving power measurements from sid instantaneous current and voltage values, said power measurements relating to less than one cycle of said AC electrical signal, wherein said power measurements are an instantaneous real power and an instantaneous imaginary power; means for deriving phase-related control values from said power measurements, wherein said phase-related control values are a phase-related real current control value obtained from the instantaneous real power divided by the instantaneous voltage magnitude and a phase-related imaginary current control value obtained from the instantaneous imaginary power divided by the instantaneous voltage magnitude; and a controller for controlling said converter on the basis of said control values, thereby to control the amplitude and phase of said voltage of said AC electrical system.
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) | 1997-09-19 | 1998-03-21 | 1998-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-09-19 | 2002-03-21 | 2002-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-09-19 | 2006-03-21 | 2006-09-20 | $7700.00 | Window Closed / Lapsed |