US3849677A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hybrid power filters employing both active and passive elements
Assignee: Westinghouse Electric Corp
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Filing: 1973-06-26
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Granted: 1974-11-19
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Expires: 1993-06-26
Abstract
Abstract A hybrid power filter employing both active and passive filtering elements retaining the advantages of these elements while overcoming the main disadvantages of each when used separately. In one embodiment of the invention, the passive element comprises a capacitor and inductor in series across the power conductors connecting a source section to a load section and tuned to the frequency of the major ripple component. In shunt with the inductor, or possibly the capacitor, is an active element which generates a synthetic ripple which opposes and eliminates any residual ripple component which may pass from the source to the load section, or vice versa, due to the inherent resistance of the passive filter or to detuning of the filter formed by the passive elements. Multiple hybrid filters of this type may be connected across the power conductors, each filter being tuned to a selected frequency in a range of expected harmonic frequencies. In another embodiment of the invention, the passive element comprises a capacitor and an inductor in parallel, the parallel combination being connected in series between the source and load, together with an active element connected across the inductor of the filter.
Inventors
- 👤 E Stacey
- 👤 E Strycula
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 15:49
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/0405
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
138 words
In an electrical system for supplying power from an electrical source section to a load section, one of said sections generating a single harmonic frequency fh to which the other section is subject to in the absence of filtering, the combination: a hybrid filter interposed between said sections, and including at least two passive filter elements initially tuned to slightly above the said single harmonic frequency fh; a shunt inductor having preselected inductance; a pair of reverse parallel thyristors, the pair being connected in series with said shunt inductor, the series combination of shunt inductor and the thyristor pair being connected in parallel with one of said passive filter elements, whereby by adjusting the phase angle of thyristor conduction, the effective inductance of said shunt inductor is adjusted to bring said hybrid filter exactly at resonance at fh.
Claim 2
Dependent Claim
138 words
In an electrical system for supplying power from an electrical source section to a load section, one of said sections generating a single harmonic frequency fh to which the other section is subject to in the absence of filtering, the combination: a hybrid filter interposed between said sections, and including at least two passive filter elements initially tuned to slightly above the said single harmonic frequency fh; a shunt inductor having preselected inductance; a pair of reverse parallel thyristors, the pair being connected in series with said shunt inductor, the series combination of shunt inductor and the thyristor pair being connected in parallel with one of said passive filter elements, whereby by adjusting the phase angle of thyristor conduction, the effective inductance of said shunt inductor is adjusted to bring said hybrid filter exactly at resonance at fh.
Claim 3
Dependent Claim
58 words
The combination of claim 1 including: a pair of adjustable d.c. voltage sources, each thyristor being connected in series with one of said d.c. sources, said d.c. sources being equal in magnitude and oppositely connecteD, whereby the losses of the passive components may be compensated for by adjusting the magnitudes of the two equal and opposite d.c. sources.
Claim 4
Dependent Claim
146 words
In an electrical system for supplying power from an electrical source section to a load section, one of said sections generating a harmonic frequency of order h to which the other section is subject to in the absence of filtering, the combination: a hybrid filter interposed between said sections, and including at least two passive filter elements; a shunt indicator having preselected inductance; a pair of reverse parallel thyristors the pair being connected in series with said shunt inductor; an autotransformer having a tap turns ratio of N1 turns to N2 turns, the series combination of shunt inductor, thyristor pair and N2 turns being connected in parallel with one of said passive filter elements, said N1 turns being connected across said load section, the untapped end of said N1 being connected to said electrical source section, the required turns ratio being N1/N2 ((h)2 - 1)/1 .
Claim 5
Dependent Claim
146 words
In an electrical system for supplying power from an electrical source section to a load section, one of said sections generating a harmonic frequency of order h to which the other section is subject to in the absence of filtering, the combination: a hybrid filter interposed between said sections, and including at least two passive filter elements; a shunt indicator having preselected inductance; a pair of reverse parallel thyristors the pair being connected in series with said shunt inductor; an autotransformer having a tap turns ratio of N1 turns to N2 turns, the series combination of shunt inductor, thyristor pair and N2 turns being connected in parallel with one of said passive filter elements, said N1 turns being connected across said load section, the untapped end of said N1 being connected to said electrical source section, the required turns ratio being N1/N2 ((h)2 - 1)/1 .
Claim 6
Dependent Claim
58 words
The combination of claim 3 including: a pair of adjustable d.c. voltage sources, each thyristor being connected in series with one of said d.c. sources, said d.c. sources being equal in magnitude and oppositely connected, whereby the losses of the passive components may be compensated for by adjusting the magnitude of the two equal and opposite d.c. sources.
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) | 1977-11-18 | 1978-05-20 | 1978-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-18 | 1982-05-20 | 1982-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-18 | 1986-05-20 | 1986-11-19 | $7700.00 | Window Closed / Lapsed |