US3707666A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Unity input displacement factor frequency changer
Assignee: Westinghouse Electric Corp
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Filing: 1971-11-12
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Granted: 1972-12-26
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Expires: 1991-11-12
Abstract
Abstract The invention relates to a frequency changer (or cycloconverter) system employing conduction controlled bilateral switches operating in a controlled switching mode to maintain a unity input displacement factor for the frequency changer system independent of load power factor and output voltage. The input displacement factor, which is often referred to as the input power factor, of the frequency changer system is defined to be the angle between the input, or source, voltage and the fundamental component of the input current drawn by the frequency changer system.
Inventors
- 👤 Laszlo Gyugyi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:49
CPC Classifications
H; H02; H02M; H02M5/00; H02M5/02; H02M5/04; H02M5/22; H02M5/25; H02M5/27; H02M5/271
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
200 words
An AC to AC frequency changer apparatus for developing an AC output voltage waveform across a load, comprising, in combination, an AC input power source, a converter circuit means including a plurality of ON-OFF conduction controlled bilateral switching means operatively connected between said AC input source and said load, each of said bilateral switching means being capable of conducting current in both directions between said input power source and said load, phase modulation conduction control circuit means operatively connected to said ON-OFF conduction controlled bilateral switching means to control the ciring angles of said bilateral switching means and sequentially render conductive said bilateral switching means in phase relationship with the alternating voltage supplied by said AC input power source, said bilateral switching means developing said AC output voltage waveform across said load, said bilateral switching means being rendered conductive by said phase modulation control conduction circuit means during both the positive and negative half cycles of the AC current flowing in said load such that the current drawn from said AC input power source is in phase with the corresponding phase voltage of said AC input power source thereby establishing a unity input displacement factor for said converter circuit means.
Claim 2
Dependent Claim
200 words
An AC to AC frequency changer apparatus for developing an AC output voltage waveform across a load, comprising, in combination, an AC input power source, a converter circuit means including a plurality of ON-OFF conduction controlled bilateral switching means operatively connected between said AC input source and said load, each of said bilateral switching means being capable of conducting current in both directions between said input power source and said load, phase modulation conduction control circuit means operatively connected to said ON-OFF conduction controlled bilateral switching means to control the ciring angles of said bilateral switching means and sequentially render conductive said bilateral switching means in phase relationship with the alternating voltage supplied by said AC input power source, said bilateral switching means developing said AC output voltage waveform across said load, said bilateral switching means being rendered conductive by said phase modulation control conduction circuit means during both the positive and negative half cycles of the AC current flowing in said load such that the current drawn from said AC input power source is in phase with the corresponding phase voltage of said AC input power source thereby establishing a unity input displacement factor for said converter circuit means.
Claim 3
Dependent Claim
195 words
Apparatus as claimed in claim 1 wheRein said converter circuit means includes a first converter circuit and a second converter circuit, said phase modulation control conduction circuit means providing phase modulated ON-OFF conduction control of the bilateral switching means of said first and second converter circuits with respect to the alternating voltage supply by said AC input power source to develop intermediate first and second output voltage waveforms respectively, said bilateral switching means of said first and second converter circuits being rendered conductive by said phase modulation control conduction circuit means during both the positive and negative half cycles of the AC output current flowing in said load to establish a unity input displacement factor for both said first and second converter circuits, said phase modulation control circuit maintaining the sum of the firing angles of said first and second converter circuit at approximately 180*, and means for combining the outputs of said first and second converter circuits, said combination resulting in reduced distortion of the current drawn from the AC input power source and reduced distortion of the AC output voltage waveform while maintaining the unity input displacement factor for said converter circuit means.
Claim 4
Dependent Claim
37 words
An AC to AC frequency changer apparatus as claimed in claim 1 wherein the average variation of the phase angle over a full output cycle established by said phase modulation conduction controlled circuit means is approximately zero.
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) | 1975-12-26 | 1976-06-26 | 1976-12-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-26 | 1980-06-26 | 1980-12-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-26 | 1984-06-26 | 1984-12-26 | $7700.00 | Window Closed / Lapsed |