US4439823A
Expired / Lapsed
US
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Converting multiphase power from one frequency to another using current waveforms
Assignee: Westinghouse Electric Corp
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Filing: 1982-01-11
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Granted: 1984-03-27
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Expires: 2002-01-11
Abstract
Abstract a multiphase AC current of one frequency is converted to a multiphase current of another frequency by a frequency changer having its output terminals terminated by a load having the impedance characteristics of a voltage source. In this arrangement the multiple phases of a practical AC current source such as a synchronous generator are connected directly to each load phase, even where the bidirectional switches of the UFC are arranged in pulse groups or a bridge configuration.
Inventors
- 👤 Laszlo Gyugyi
- 👤 Geoffrey M. Smith
- 👤 Eric J. Stacey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:34
CPC Classifications
H; H02; H02M; H02M5/00; H02M5/02; H02M5/04; H02M5/22; H02M5/25; H02M5/27; H02M5/272
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
173 words
Apparatus for generating a multiphase output waveform of a desired frequency from a multiphase input waveform of another frequency, said apparatus comprising: a multiphase AC source for generating said multiphase input waveform, said source having an impedance which is predominatly inductive; a plurality of output lines; an array of bidirectional switches connected directly between each phase of the AC source and each output line; control means for sequentially turning on and off said bidirectional switches associated with each output line in a repetitive pattern such that each phase of the AC source conducts current to only one of said output lines at a time with segments of the current from each phase of the AC source being sequentially applied to the output lines, such that each phase of the AC source conducts current through at least one of said bidirectional switches at all times, to generate thereon the output waveform having a fundamental component of said desired frequency; and load means connected across the output lines having an impedance which is sbustantially noninductive.
Claim 2
Dependent Claim
173 words
Apparatus for generating a multiphase output waveform of a desired frequency from a multiphase input waveform of another frequency, said apparatus comprising: a multiphase AC source for generating said multiphase input waveform, said source having an impedance which is predominatly inductive; a plurality of output lines; an array of bidirectional switches connected directly between each phase of the AC source and each output line; control means for sequentially turning on and off said bidirectional switches associated with each output line in a repetitive pattern such that each phase of the AC source conducts current to only one of said output lines at a time with segments of the current from each phase of the AC source being sequentially applied to the output lines, such that each phase of the AC source conducts current through at least one of said bidirectional switches at all times, to generate thereon the output waveform having a fundamental component of said desired frequency; and load means connected across the output lines having an impedance which is sbustantially noninductive.
Claim 3
Dependent Claim
20 words
The apparatus of claim 1 wherein the said AC source has an inductive reactance of 0.2 per unit or greater.
Claim 4
Dependent Claim
13 words
The apparatus of claim 1 wherein said AC source is a synchronous generator.
Claim 5
Dependent Claim
25 words
The apparatus of claim 1 wherein said AC source is a multiphase AC generator with an external inductor in series with each output phase winding.
Claim 6
Dependent Claim
59 words
The apparatus of claim 1 wherein said load includes shunt impedance means connected across the output lines directly to the output side of said bidirectional switches, said shunt impedance means providing a low impedance path for the harmonic currents resulting from the switching to the output lines by the bidirectional switches of current segments from successive AC source phases.
Claim 7
Dependent Claim
15 words
The apparatus of claim 5 wherein said impedance means comprise capacitors shunting the output lines.
Claim 8
Dependent Claim
30 words
The apparatus of claim 5 wherein the shunt impedance means comprises a filter network including a plurality of series connected inductors and capacitors tuned to the principal harmonic current frequencies.
Claim 9
Dependent Claim
154 words
A frequency changer for generating on a plurality of output lines connected to a load having the impedance characteristics of a voltage source, a multiphase output waveform having a desired fundamental frequency from a multiphase AC current source, said frequency changer comprising: bidirectional switches connected directly between each phase of the AC current source and each output line, and control means for sequentially turning on and off said bidirectional switches associated with each output line in a repetitive pattern such that each phase of the AC current source conducts current to only one of said output lines at a time with segments of the current from each phase of the AC current source being sequentially applied to the output line at instants which produce an output current waveform having a fundamental component of said desired frequency and such that at least one bidirectional switch associated with each source phase is on at all times.
Claim 10
Dependent Claim
154 words
A frequency changer for generating on a plurality of output lines connected to a load having the impedance characteristics of a voltage source, a multiphase output waveform having a desired fundamental frequency from a multiphase AC current source, said frequency changer comprising: bidirectional switches connected directly between each phase of the AC current source and each output line, and control means for sequentially turning on and off said bidirectional switches associated with each output line in a repetitive pattern such that each phase of the AC current source conducts current to only one of said output lines at a time with segments of the current from each phase of the AC current source being sequentially applied to the output line at instants which produce an output current waveform having a fundamental component of said desired frequency and such that at least one bidirectional switch associated with each source phase is on at all times.
Claim 11
Dependent Claim
92 words
The frequency changer of claim 8 wherein the phases of the AC current source and the load are midpoint connected, wherein said bidirectional switches connected between the individual output lines and each phase of the AC current source are divided into pulse groups and wherein said control means sequentially turns on and off said switches in a repetitive pattern such that one switch in each pulse group is turned on at all times, said bidirectional switches in each pulse group associated with each output line being connected directly to the output line.
Claim 12
Dependent Claim
24 words
The frequency changer of claim 9 including capacitor means connected across the output lines directly to the output side of the associated bidirectional switches.
Claim 13
Dependent Claim
37 words
The frequency changer of claim 10 wherein said capacitor means have sufficient capacitance to sink the current transients resulting from the switching to the output lines by the bidirectional switches of current segments from successive source phases.
Claim 14
Dependent Claim
44 words
The frequency changer of claim 10 or 11 including a neutral line connected between the midpoint connection of the phases of the AC current source and of the load and wherein said capacitor means are connected between each output line and said neutral line.
Claim 15
Dependent Claim
53 words
The frequency changer of claim 8 wherein each phase of the AC current source is isolated and bidirectional switches connecting each source phase to each output line are arranged in a bridge pattern with the bidirectional switches connecting the individual output lines with each source phase all connected directly to said output line.
Claim 16
Dependent Claim
49 words
The frequency changer of claim 13 wherein the number of phases of said AC current source exceed the number of output lines and wherein said control means turns on bidirectional switches connecting more than one AC current source phase directly to an individual output line at the same time.
Claim 17
Dependent Claim
24 words
The frequency changer of claim 13 including capacitor means connected across the output lines directly to the output side of the associated bidirectional switches.
Claim 18
Dependent Claim
37 words
The frequency changer of claim 13 wherein said capacitor means have sufficient capacitance to sink the current transients resulting from the switching to the output lines by the bidirectional switches of current segments from successive source phases.
Claim 19
Independent Claim
118 words
A method of generating a multiphase AC waveform of a desired frequency on a plurality of output lines connected to a load, said method comprising the steps of: generating a multiphase AC input current waveform of another frequency; sequentially switching segments of each phase of the input current waveform directly to each output line at instants which generate on said output lines a multiphase output current waveform having a fundamental component equal to the desired frequency, such that each phase of the input current waveform is connected to one and only one of said output lines at all times; and shunting between the output lines the harmonic components of the output current waveform generated on said output lines.
Claim 20
Independent Claim
118 words
A method of generating a multiphase AC waveform of a desired frequency on a plurality of output lines connected to a load, said method comprising the steps of: generating a multiphase AC input current waveform of another frequency; sequentially switching segments of each phase of the input current waveform directly to each output line at instants which generate on said output lines a multiphase output current waveform having a fundamental component equal to the desired frequency, such that each phase of the input current waveform is connected to one and only one of said output lines at all times; and shunting between the output lines the harmonic components of the output current waveform generated on said output lines.
Claim 21
Dependent Claim
87 words
The method of claim 17 including the step of midpoint connecting the phases of the input current waveform, and wherein the step of sequentially switching segments of each phase of the input current waveform to each output line includes switching said current segments in pulse groups with one current segment in each group being switched directly to the associated output line at all times such that more than one current segment from the input current waveform is applied directly to each output line at the same time.
Claim 22
Dependent Claim
52 words
The method of claim 18 including connecting a neutral line between the midpoint connection of the phases of the AC current waveform and a midpoint connection of the load and wherein the step of shunting the harmonic components of the output current waveform comprises shunting said harmonic currents to said neutral line.
Claim 23
Dependent Claim
50 words
The method of claim 17 wherein each phase of the input current waveform is isolated and wherein the step of sequentially switching segments of each phase of the input current waveform directly to each output line includes switching the current segments in a bridge pattern directly to each output line.
Claim 24
Dependent Claim
68 words
The method of claim 10 wherein the number of phases of the input AC current waveform exceeds the number of output lines and wherein said step of sequentially switching segments of each phase of the AC input current waveform directly to each output line includes switching segments of current directly to an output line from more than one phase of the AC input current waveform at a time.
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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) | 1987-03-27 | 1987-09-26 | 1988-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-27 | 1991-09-26 | 1992-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-27 | 1995-09-26 | 1996-03-27 | $7700.00 | Window Closed / Lapsed |