US4922400A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Neutral forming circuit
Assignee: Sundstrand Corp
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Filing: 1989-08-03
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Granted: 1990-05-01
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Expires: 2009-08-03
Abstract
Abstract Prior neutral forming circuits for use in developing a neutral voltage for loads coupled to an inverter have been unduly large and heavy or have required that the inverter be operated by a half bridge control which causes less easily filtered harmonics to be produced in the inverter output. In order to overcome these problems, a neutral forming circuit includes first and second impedances coupled together at a junction to form a series combination which is coupled across a pair of DC link conductors coupled to an inverter input and a third impedance coupled between the junction and a neutral terminal at which the neutral voltage is formed, the first through third impedances forming a resonant circuit having a resonant frequency substantially equal to the output frequency of the inverter.
Inventors
- 👤 Alexander Cook
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 05:52
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/53; H02M7/537; H02M7/5387; Y; Y02; Y02B; Y02B70/00; Y02B70/10
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
94 words
A neutral forming circuit which develops a neutral voltage relative to an AC voltage produced at an output frequency by an inverter coupled to first and second DC link conductors, comprising: first and second impedances coupled together at a junction to form a series combination which is coupled across the DC link conductors; and a third impedance coupled between the junction and a neutral terminal at which the neutral voltage is formed, the first through third impedances forming a resonant circuit having a resonant frequency substantially equal to the output frequency of the inverter.
Claim 2
Dependent Claim
94 words
A neutral forming circuit which develops a neutral voltage relative to an AC voltage produced at an output frequency by an inverter coupled to first and second DC link conductors, comprising: first and second impedances coupled together at a junction to form a series combination which is coupled across the DC link conductors; and a third impedance coupled between the junction and a neutral terminal at which the neutral voltage is formed, the first through third impedances forming a resonant circuit having a resonant frequency substantially equal to the output frequency of the inverter.
Claim 3
Dependent Claim
19 words
The neutral forming circuit of claim 1, wherein the first and second impedances comprise capacitors having substantially equal capacitances.
Claim 4
Dependent Claim
14 words
The neutral forming circuit of claim 2, wherein the third impedance comprises an inductor.
Claim 5
Dependent Claim
103 words
A neutral forming circuit which develops a neutral voltage relaive to three-phase AC voltages produced at an output frequency by a three-phase inverter operated by a full bridge inverter control and having inputs coupled to first and second DC link conductors, comprising: first and second capacitors coupled together at a junction to form a series combination which is coupled across the DC link conductors; and an inductor coupled between the junction and a neutral terminal at which the neutral voltage is formed, the capacitors and inductor forming a resonant circuit having a resonant frequency substantially equal to the output frequency of the inverter.
Claim 6
Dependent Claim
103 words
A neutral forming circuit which develops a neutral voltage relaive to three-phase AC voltages produced at an output frequency by a three-phase inverter operated by a full bridge inverter control and having inputs coupled to first and second DC link conductors, comprising: first and second capacitors coupled together at a junction to form a series combination which is coupled across the DC link conductors; and an inductor coupled between the junction and a neutral terminal at which the neutral voltage is formed, the capacitors and inductor forming a resonant circuit having a resonant frequency substantially equal to the output frequency of the inverter.
Claim 7
Dependent Claim
17 words
The neutral forming circuit of claim 4, wherein the first and second capacitors have substantially equal capacitances.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-04-30 | 1993-10-30 | 1994-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-30 | 1997-10-30 | 1998-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-30 | 2001-10-30 | 2002-05-01 | $7700.00 | Window Closed / Lapsed |