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High-frequency heating device

  • US 20070195561A1
  • Filed: 04/04/2005
  • Published: 08/23/2007
  • Est. Priority Date: 04/07/2004
  • Status: Active Grant
First Claim
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1. A high-frequency heating apparatus for driving a magnetron, comprising:

  • a DC power supply including an AC power supply, a rectifier circuit for rectifying a voltage of the AC power supply, and a smoothing capacitor for smoothing an output voltage of the rectifier circuit;

    a series circuit including two semiconductor switching devices, the series circuit being connected in parallel to the AC power supply;

    a resonance circuit connected to a primary winding of a leakage transformer and a capacitor, one end of the resonance circuit being connected to a middle point of the series circuit in an AC equivalent circuit while the other end of the resonance circuit is connected to one end of the AC power supply;

    a drive unit for driving each of the semiconductor switching devices;

    a rectifier unit connected to a secondary winding of the leakage transformer;

    a magnetron connected to the rectifier unit; and

    a dead time generation circuit for turning off the semiconductor switching devices concurrently, wherein the drive unit has a function of limiting the lowest frequency of a frequency with which the semiconductor switching devices are driven, so that the lowest frequency is set to be high at the beginning of operation of the high-frequency heating apparatus, and the lowest frequency is set to be lower gradually thereafter.

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