US4051545A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for overvoltage protection of a direct converter in the rotor circuit of an asynchronous machine
Assignee: BBC Brown Boveri AG Switzerland
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Filing: 1976-01-06
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Granted: 1977-09-27
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Expires: 1996-01-06
Abstract
Abstract Apparatus for overvoltage protection of a direct converter utilizing controllable semi-conductor valves and whose output is connected to the rotor circuit of an asynchronous electrical machine includes a stepped impedance circuit which is controlled by a stepped current valve switching circuit. The stepped impedance circuit is connected to the output terminals of the converter and the valves of the switching circuit are controlled in accordance with the amplitude of any transient overvoltage induced in the rotor circuit in such manner that the total resistance value of the impedance circuit varies inversely with the amplitude of the overvoltage. The impedance switchable into and out of the circuit can be arranged in series, or in parallel, or in series-parallel.
Inventors
- 👤 Albert Kloss
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:38
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/08; H02H7/0833; H02H7/10; H02H7/12; H02H9/00; H02H9/04
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
114 words
Apparatus for overvoltage protection of a direct converter utilizing controllable semi-conductor valves and whose output is connected to the rotor circuit of an asynchronous electrical machine which comprises a stepped impedance circuit connected across the output of said direct converter, said impedance circuit being constituted by a plurality of impedance elements selectively connectible electrically in parallel, and a stepped current valve switching circuit comprising controllable semi-conductor valves connected respectively in circuit with said impedance elements, the valves of said switching circuit being controlled in accordance with the amplitude of any transient overvoltage induced in said rotor circuit such that the total resistance of said impedance circuit varies inversely with the amplitude of said overvoltage.
Claim 2
Dependent Claim
114 words
Apparatus for overvoltage protection of a direct converter utilizing controllable semi-conductor valves and whose output is connected to the rotor circuit of an asynchronous electrical machine which comprises a stepped impedance circuit connected across the output of said direct converter, said impedance circuit being constituted by a plurality of impedance elements selectively connectible electrically in parallel, and a stepped current valve switching circuit comprising controllable semi-conductor valves connected respectively in circuit with said impedance elements, the valves of said switching circuit being controlled in accordance with the amplitude of any transient overvoltage induced in said rotor circuit such that the total resistance of said impedance circuit varies inversely with the amplitude of said overvoltage.
Claim 3
Dependent Claim
114 words
Apparatus for overvoltage protection of a direct converter utilizing controllable semi-conductor valves and whose output is connected to the rotor circuit of an asynchronous electrical machine which comprises a stepped impedance circuit connected across the output of said direct converter, said impedance circuit being constituted by a plurality of impedance elements selectively connectible electrically in series-parallel, and a stepped current valve switching circuit comprising controllable semi-conductor valves connected respectively in circuit with said impedance elements, the valves of said switching circuit being controlled in accordance with the amplitude of any transient overvoltage induced in said rotor circuit such that the total resistance of said impedance circuit varies inversely with the amplitude of said overvoltage.
Claim 4
Dependent Claim
114 words
Apparatus for overvoltage protection of a direct converter utilizing controllable semi-conductor valves and whose output is connected to the rotor circuit of an asynchronous electrical machine which comprises a stepped impedance circuit connected across the output of said direct converter, said impedance circuit being constituted by a plurality of impedance elements selectively connectible electrically in series-parallel, and a stepped current valve switching circuit comprising controllable semi-conductor valves connected respectively in circuit with said impedance elements, the valves of said switching circuit being controlled in accordance with the amplitude of any transient overvoltage induced in said rotor circuit such that the total resistance of said impedance circuit varies inversely with the amplitude of said overvoltage.
Claim 5
Dependent Claim
114 words
Apparatus for overvoltage protection of a direct converter utilizing controllable semi-conductor valves and whose output is connected to the rotor circuit of an asynchronous electrical machine which comprises a stepped impedance circuit constituted by a plurality of impedance elements, a stepped current valve switching circuit comprising controllable semi-conductor valves correlated respectively with said impedance elements, the valves of said switching circuit being selectively controlled in accordance with the amplitude of any transient overvoltage induced in said rotor circuit such that the total resistance of said impedance circuit varies inversely with the amplitude of said overvoltage, and a controllable semi-conductor valve circuit connected intermediate said stepped impedance circuit and the output of said direct converter.
Claim 6
Dependent Claim
114 words
Apparatus for overvoltage protection of a direct converter utilizing controllable semi-conductor valves and whose output is connected to the rotor circuit of an asynchronous electrical machine which comprises a stepped impedance circuit constituted by a plurality of impedance elements, a stepped current valve switching circuit comprising controllable semi-conductor valves correlated respectively with said impedance elements, the valves of said switching circuit being selectively controlled in accordance with the amplitude of any transient overvoltage induced in said rotor circuit such that the total resistance of said impedance circuit varies inversely with the amplitude of said overvoltage, and a controllable semi-conductor valve circuit connected intermediate said stepped impedance circuit and the output of said direct converter.
Claim 7
Dependent Claim
29 words
Apparatus as defined in claim 3 for overvoltage protection of single-phase direct converter wherein said intermediately connected controllable semi-conductor valve circuit is constituted by a single phase bridge circuit.
Claim 8
Dependent Claim
29 words
Apparatus as defined in claim 3 for overvoltage protection of a three-phase direct converter wherein said intermediately connected controllable semi-conductor valve circuit is constituted by a three-phase bridge circuit.
Claim 9
Dependent Claim
32 words
Apparatus as defined in claim 3 for overvoltage protection of a star connected three-phase direct converter wherein said intermediately connected controllable semi-conductor valve circuit is constituted by two current valve star connections.
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) | 1980-09-26 | 1981-03-28 | 1981-09-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-26 | 1985-03-28 | 1985-09-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-26 | 1989-03-28 | 1989-09-27 | $7700.00 | Window Closed / Lapsed |