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Reactive power processing circuit for a current source GTO invertor

  • US 4,721,897 A
  • Filed: 01/21/1987
  • Issued: 01/26/1988
  • Est. Priority Date: 01/24/1986
  • Status: Expired due to Fees
First Claim
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1. A reactive power processing circuit for a current source invertor, comprising:

  • (a) a power rectifier which carries out a gate phase control of a plurality of switching elements to convert an alternating current derived from an alternating current source into a corresponding direct current;

    (b) a smoothing circuit having at least one direct current reactor for smoothing the direct current derived from the power rectifier so as to produce a smoothed direct current;

    (c) an invertor main circuit having a plurality of bridge-connected gate turn off thyristors (GTO thyristors) for inverting the direct current derived from the smoothing circuit into an alternating current and for deriving a load with the alternating current at output sides thereof;

    (d) a fly wheel circuit having a plurality of bridge-connected diodes whose alternating current sides are connected to the corresponding output sides of the invertor main circuit, for rectifying a reactive current derived from the load;

    (e) a capacitor, connected across a direct current side of the fly wheel circuit, for storing a commutation surge voltage generated in the load;

    (f) a pair of GTO thyristors, connected to the capacitor in their forward directions, for operatively discharging a charge across the capacitor toard positive and negative poles of the power rectifier; and

    (g) a control circuit for triggering the pair of GTO thyristors to discharge the excessive charge across the capacitor and for continuing to send triggering pulses to the switching elements of the power rectifier for an interval required for a power rectifying operation of the power rectifier so that the switching elements are retriggered when a discharge operation of the pair of GTO thyristors is completed.

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