Voltage divider for a thyristor valve control circuit
AssigneeASEA Aktiebolag
InventorGunnar Asplund
Life of this patent
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Abstract
A power converter includes a plurality of thyristors, each of which is controlled by a control circuit. A multi-section voltage divider is connected in parallel with a thyristor and provides the control circuit with power as well as means for measuring voltage across the thyristor. The present voltage divider components minimize the space required and cost of fabrication.
Claims10
In a converter valve having at least one thyristor and a control circuit for firing the thyristor, a voltage distribution circuit comprising:
- voltage dividing means, having a plurality of interconnected sections, connected in parallel across the thyristor;
- means connected between preselected points of a first section of the voltage divider for measuring a voltage thereacross which is substantially proportional to the voltage across the thyristor;
- and
- means connected between points of a second preselected section of the divider for connection of a supply voltage to the control circuit;
- wherein the first section of the voltage divider is connected for low frequency voltage supply of the control circuit and wherein a third section of the voltage divider is connected in circuit with the first and second sections, the third section connected for high frequency voltage supply of the control circuit, the third section having a junction point therein for permitting measurement of high frequency voltage of the thyristor.
In a converter valve having a plurality of series connected thyristors, each thyristor having a control circuit for firing the thyristor, a voltage distribution circuit comprising:
- for each thyristor a voltage dividing means connected in parallel with the thyristor, each of said voltage dividing means comprising
- (a) a first voltage divider (R3, R4, R5) section connected in parallel with the thyristor to derive from low frequency components, including a direct voltage component, of the thyristor voltage a supply voltage to the control circuit and a measuring voltage substantially proportional to the thyristor voltage, first impedance means (R6) connecting an intermediate point (A) of said first voltage divider section to a supply voltage bar for said control circuit, first measuring voltage divider means (R4, R5) connected to said intermediate point (A) for deriving said measuring voltage,
- (b) a second voltage divider section (C1, R1, R2, C2, C3, C4) connected in parallel with the thyristor to derive from high frequency components of the thyristor voltage a supply voltage for the control circuit, means connecting said second voltage divider section to said supply voltage bar.
Dependencies are inferred from the claim text.