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AssigneeBBC Brown, Boveri & Company, Limited
InventorAlbert Kloss
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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.
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.
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.
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.
Dependencies are inferred from the claim text.