US3838331A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Three-phase inverter
Assignee: Danfoss AS
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Filing: 1973-02-02
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Granted: 1974-09-24
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Expires: 1993-02-02
Abstract
Abstract A three-phase inverter for producing a stepped voltage approximating to a sinusoidal form, and largely free of odd harmonics, wherein, for the purpose of producing each phase voltage a basic and two additional rectangular impulses are summed, the basic impulse being shortened in relation to a halfwave and occupying substantially the entire amplitude-time area of the phase voltage, and the additional impulses having a considerably smaller amplitude and shorter duration than the basic impulse. One of the additional impulses procedes and the other is superimposed on a basic impulse of the same polarity.
Inventors
- 👤 A Jensen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 03:14
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/483; H02M7/49
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
191 words
A three-phase inverter for producing a stepped output voltage approximating to a sinusoidal form, the inverter comprising for each phase voltage: first means to produce a first voltage comprising a series of basic rectangular voltage impulses of alternating polarity, each said basic impulse having a duration of less than 180* and occupying substantially all the amplitudetime area of the respective phase voltage, and a series of first additional rectangular voltage impulses of alternating polarity, each said first additional voltage impulse having a duration substantially less than 180* and equal to 180* minus the duration of a said basic voltage impulse and preceding a said basic voltage impulse of the same plarity; second means to produce a series of second additional rectangular voltage impulses of alternating polarity, each said second additional voltage impulse having a duration substantially less than 180* and a time position on the opposite side of the center of a said basic impulse of the same polarity relative to said first additional impulse preceding said basic impulse; and summation means to sum said first voltage and said series of second additional rectangular voltage impulses to produce said phase voltage.
Claim 2
Dependent Claim
191 words
A three-phase inverter for producing a stepped output voltage approximating to a sinusoidal form, the inverter comprising for each phase voltage: first means to produce a first voltage comprising a series of basic rectangular voltage impulses of alternating polarity, each said basic impulse having a duration of less than 180* and occupying substantially all the amplitudetime area of the respective phase voltage, and a series of first additional rectangular voltage impulses of alternating polarity, each said first additional voltage impulse having a duration substantially less than 180* and equal to 180* minus the duration of a said basic voltage impulse and preceding a said basic voltage impulse of the same plarity; second means to produce a series of second additional rectangular voltage impulses of alternating polarity, each said second additional voltage impulse having a duration substantially less than 180* and a time position on the opposite side of the center of a said basic impulse of the same polarity relative to said first additional impulse preceding said basic impulse; and summation means to sum said first voltage and said series of second additional rectangular voltage impulses to produce said phase voltage.
Claim 3
Dependent Claim
42 words
An inverter according to claim 1 wherein said summation means comprises a transformer having an output terminal from which in use said phase voltage is derived, and wherein said first voltage is supplied to said output terminal without transformation by said transformer.
Claim 4
Dependent Claim
82 words
An inverter according to claim 1 wherein said first means comprises means to produce two similar wave-trains which consist of 180* square-wave impulses and which are offset in phase relative to one another by 180* minus the duration of a said basic impulse, an impendance to which in use said wave-trains are supplied, and a tapping on said impendance and displaced from the mid-point thereof for the purpose of producing said first additional impulses from which tapping said first voltage is derived.
Claim 5
Dependent Claim
14 words
An inverter according to claim 3 wherein said tapping is 7.8% from said mid-point.
Claim 6
Dependent Claim
38 words
An inverter according to claim 3 comprising for each phase a transformer which forms said summation means, said transformer having a primary winding which forms said impendance and a secondary winding to which said output terminal is connected.
Claim 7
Dependent Claim
43 words
An inverter according to claim 5 wherein said transformers each have a primary to secondary winding ratio of 1 to 0.155, and each said tapping is connected to a said output terminal by a path comprising said secondary winding of an adjacent phase.
Claim 8
Dependent Claim
20 words
An inverter according to claim 6 wherein said windings of said transformers are all wound on a common iron core.
Claim 9
Dependent Claim
53 words
An inverter according to claim 1 wherein each said basic impulse has a duration of 150*, and each said first additional impulse has a duration of 30and each said second additional impulse has a duration of 30* and its distance from the trailing edge of the associated said basic impulse is also 30*.
Claim 10
Dependent Claim
36 words
An inverter according to claim 1 wherein the amplitude of each said first additional impulse is 15.5 percent and that of each said second additional impulse 31 percent of the amplitude of each said basic impulse.
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) | 1977-09-23 | 1978-03-25 | 1978-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-23 | 1982-03-25 | 1982-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-23 | 1986-03-25 | 1986-09-24 | $7700.00 | Window Closed / Lapsed |