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Discharge circuit for smoothing capacitor of DC power supply

  • US 8,436,590 B2
  • Filed: 08/06/2010
  • Issued: 05/07/2013
  • Est. Priority Date: 08/07/2009
  • Status: Active Grant
First Claim
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1. A discharge circuit for a DC power supply smoothing capacitor that is used in a power conversion device that is supplied with electrical power from a DC power supply via a switch comprising:

  • a resistor that discharges charge in the capacitor;

    a switch connected in series with the resistor, that either passes or intercepts discharge current flowing from the capacitor to the resistor;

    a measurement circuit that measures a terminal voltage of the capacitor; and

    a control circuit that controls continuity and discontinuity of the switch;

    wherein the control circuit, after having made the switch continuous and starting discharge of the capacitor by the resistor, if a terminal voltage of the capacitor as measured by the measurement circuit exceeds a voltage decrease characteristic set in advance, makes the switch discontinuous and stops discharge by the resistor, and does not restart discharge until a first predetermined time period elapses during which a temperature of the resistor decreases.

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