US3715649A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Staggered phase pulse width modulated inverter apparatus
Assignee: Westinghouse Electric Corp
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Filing: 1967-01-25
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Granted: 1973-02-06
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Expires: 1987-01-25
Abstract
Abstract This disclosure describes an inverter utilizing semiconductor switching devices, such as transistors or gate controlled switches, in the legs of the inverter. The legs are connected in a bridge circuit and to a source of direct current. A filter network is connected between the legs and a load across which the alternating output of the inverter is to be developed. The devices are gated on by the application of pulse width modulated signals having an actual carrier frequency to the control electrodes of the devices of the various legs of the inverter. The pulse width modulated signals are applied to the various legs in a predetermined staggered phase relationship so that the effective carrier frequency as seen by the filter network is a higher multiple of the actual carrier frequency. Thus, the filter network need only filter out the effective carrier frequency rather than the lower actual carrier frequency, while the switching devices are switched at the actual carrier frequency at high efficiency.
Inventors
- 👤 R Ravas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:10
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/505; H02M7/515; H02M7/525; H02M7/527
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
229 words
In inverter apparatus operative with a source of direct current for supplying a load circuit with alternating current having a predetermined output frequency, the combination of: a bridge circuit including a plurality of legs connected operatively across said source of direct current, each of said legs including a pair of switching devices operatively connected and operative to be placed in a selected open or closed circuit switched state; means for providing pulse width modulated signals having a predetermined carrier frequency and being so modulated to have an average value varying at said predetermined output frequency; means for applying said pulse width modulated signals to said switching devices of said plurality of legs, respectively, in a predetermined phase relationship so that said devices in each of said legs are placed in an open or closed circuit switch state in response thereto; and filter means operatively connecting said legs of said bridge circuit and said load circuit, said filter means being so selected to reject frequencies above and including a given multiple of said predetermined carrier frequency, said predetermined phase relationship being such that said predetermined carrier frequency does not appear across said load circuit and the effective carrier frequency appears to be said multiple of said predetermined frequency that is rejected by said filter means with said alternating current having a predetermined output frequency being applied to said load circuit.
Claim 2
Dependent Claim
229 words
In inverter apparatus operative with a source of direct current for supplying a load circuit with alternating current having a predetermined output frequency, the combination of: a bridge circuit including a plurality of legs connected operatively across said source of direct current, each of said legs including a pair of switching devices operatively connected and operative to be placed in a selected open or closed circuit switched state; means for providing pulse width modulated signals having a predetermined carrier frequency and being so modulated to have an average value varying at said predetermined output frequency; means for applying said pulse width modulated signals to said switching devices of said plurality of legs, respectively, in a predetermined phase relationship so that said devices in each of said legs are placed in an open or closed circuit switch state in response thereto; and filter means operatively connecting said legs of said bridge circuit and said load circuit, said filter means being so selected to reject frequencies above and including a given multiple of said predetermined carrier frequency, said predetermined phase relationship being such that said predetermined carrier frequency does not appear across said load circuit and the effective carrier frequency appears to be said multiple of said predetermined frequency that is rejected by said filter means with said alternating current having a predetermined output frequency being applied to said load circuit.
Claim 3
Dependent Claim
229 words
In inverter apparatus operative with a source of direct current for supplying a load circuit with alternating current having a predetermined output frequency, the combination of: a bridge circuit including a plurality of legs connected operatively across said source of direct current, each of said legs including a pair of switching devices operatively connected and operative to be placed in a selected open or closed circuit switched state; means for providing pulse width modulated signals having a predetermined carrier frequency and being so modulated to have an average value varying at said predetermined output frequency; means for applying said pulse width modulated signals to said switching devices of said plurality of legs, respectively, in a predetermined phase relationship so that said devices in each of said legs are placed in an open or closed circuit switch state in response thereto; and filter means operatively connecting said legs of said bridge circuit and said load circuit, said filter means being so selected to reject frequencies above and including a given multiple of said predetermined carrier frequency, said predetermined phase relationship being such that said predetermined carrier frequency does not appear across said load circuit and the effective carrier frequency appears to be said multiple of said predetermined frequency that is rejected by said filter means with said alternating current having a predetermined output frequency being applied to said load circuit.
Claim 4
Dependent Claim
229 words
In inverter apparatus operative with a source of direct current for supplying a load circuit with alternating current having a predetermined output frequency, the combination of: a bridge circuit including a plurality of legs connected operatively across said source of direct current, each of said legs including a pair of switching devices operatively connected and operative to be placed in a selected open or closed circuit switched state; means for providing pulse width modulated signals having a predetermined carrier frequency and being so modulated to have an average value varying at said predetermined output frequency; means for applying said pulse width modulated signals to said switching devices of said plurality of legs, respectively, in a predetermined phase relationship so that said devices in each of said legs are placed in an open or closed circuit switch state in response thereto; and filter means operatively connecting said legs of said bridge circuit and said load circuit, said filter means being so selected to reject frequencies above and including a given multiple of said predetermined carrier frequency, said predetermined phase relationship being such that said predetermined carrier frequency does not appear across said load circuit and the effective carrier frequency appears to be said multiple of said predetermined frequency that is rejected by said filter means with said alternating current having a predetermined output frequency being applied to said load circuit.
Claim 5
Dependent Claim
65 words
In the inverter apparatus of claim 1 wherein: whenever one of said pair of said switching devices is placed in a closed circuit switched state the other of said pair is placed in an open circuit switched state, predetermined ones of said pair of said switching devices in each of said legs being placed in the same switched state during the same period of time.
Claim 6
Dependent Claim
129 words
In the inverter apparatus of claim 2 wherein: said bridge circuit including a First and a second leg connected on the opposite sides of said bridge circuit, each of said legs including a first and a second switching device connected in series with a junction formed therebetween, said filter means operatively connected between said junctions in each of said legs and said load, said predetermined phase relationship for said pulse width modulated signals applied to said switching devices in said first and second legs being substantially 180* out of phase with each other, said first and said second devices of said first and second legs respectively being placed in the same switched state during the same period of time, said given multiple of said predetermined carrier frequency being two.
Claim 7
Dependent Claim
87 words
In the inverter apparatus of claim 2, wherein: said bridge circuit including first, second, third and fourth legs, said first and said second legs being connected on one side of bridge circuit and said third and fourth legs being connected on the other side thereof, said predetermined phase relationship for said pulse width modulate signals being applied to said switching devices of said first, second, third and fourth legs, respectively being substantially 0*, 180*, 90* and 270*, said given multiple of said predetermined carrier frequency being four.
Claim 8
Dependent Claim
15 words
In the inverter apparatus of claim 2 wherein: said switching devices comprise gate controlled switches.
Claim 9
Dependent Claim
18 words
In the inverter apparatus of claim 2 wherein: said switching devices comprise transistors operative in a switching mode.
Claim 10
Dependent Claim
26 words
In the inverter apparatus of claim 6, further including: means for preventing said transistors from going into saturation so as to decrease the switching time thereof.
Claim 11
Dependent Claim
36 words
In the inverter apparatus of claim 2, further including: a unidirectional device connected across each of said switching devices to provide a reverse current path thereacross so that said inverter may be operative with reactive loads.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-06 | 1976-08-07 | 1977-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-06 | 1980-08-07 | 1981-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-06 | 1984-08-07 | 1985-02-06 | $7700.00 | Window Closed / Lapsed |