US3761797A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical filters
Assignee: Brentford Electric Ltd
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Filing: 1971-12-07
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Granted: 1973-09-25
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Expires: 1991-12-07
Abstract
Abstract A ripple filter in which the magnetic flux in the core of a series choke due to direct current through the primary winding forming the choke is opposed by an equal flux through a secondary winding to keep the core out of saturation. Alternatively or additionally the ripple current is opposed by an anti-phase current through a secondary winding on the core in order to reduce the ripple actively.
Inventors
- 👤 F Spooner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:53
CPC Classifications
H; H02; H02M; H02M1/00; H02M1/40; H02M1/14; H02M1/15
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
186 words
A filter circuit comprising a source of rectified electric current having a direct component and a ripple component, a load therefor, a choke winding in series between the source and the load, a magnetic core carrying said choke winding, a secondary winding on said core and a feedback circuit including said secondary winding, and resistive means disposed for receiving said direct component and proportioned to develop a direct current in fixed proportion to said direct component and means for feeding said direct current through said secondary winding, said direct current having a magnetic effect on said core in substantially complete opposition to the magnetic effect on said core of said direct component; said means for receiving the direct component comprising a first resistor means in series with said load and said feedback circuit includes second, third and fourth resistor means coupled in series in a branch in parallel with said first resistor means, said resistor means determining the proportionality of said direct current and said direct component, said feedback circuit further comprising amplifier means connected in series with said secondary winding across said third resistor means.
Claim 2
Dependent Claim
186 words
A filter circuit comprising a source of rectified electric current having a direct component and a ripple component, a load therefor, a choke winding in series between the source and the load, a magnetic core carrying said choke winding, a secondary winding on said core and a feedback circuit including said secondary winding, and resistive means disposed for receiving said direct component and proportioned to develop a direct current in fixed proportion to said direct component and means for feeding said direct current through said secondary winding, said direct current having a magnetic effect on said core in substantially complete opposition to the magnetic effect on said core of said direct component; said means for receiving the direct component comprising a first resistor means in series with said load and said feedback circuit includes second, third and fourth resistor means coupled in series in a branch in parallel with said first resistor means, said resistor means determining the proportionality of said direct current and said direct component, said feedback circuit further comprising amplifier means connected in series with said secondary winding across said third resistor means.
Claim 3
Dependent Claim
63 words
A filter circuit according to claim 1 further comprising a circuit path in parallel with said load, means in said circuit path for blocking direct current, and further circuit means coupling said path to a secondary winding on said core, said further circuit means and said latter winding coupling to said choke winding an alternating current in phase opposition to said ripple component.
Claim 4
Dependent Claim
24 words
A filter circuit according to claim 2 wherein the said further circuit means comprises an amplifier coupled to drive said latter winding in push-pull.
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) | 1976-09-24 | 1977-03-26 | 1977-09-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-24 | 1981-03-26 | 1981-09-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-24 | 1985-03-26 | 1985-09-25 | $7700.00 | Window Closed / Lapsed |