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Power supply device

  • US 10,128,649 B2
  • Filed: 03/11/2015
  • Issued: 11/13/2018
  • Est. Priority Date: 03/11/2015
  • Status: Active Grant
First Claim
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1. A power supply device comprising:

  • a resistor to limit an electric current supplied from an alternating-current power supply;

    a switch that is connected in parallel with the resistor;

    a rectifier circuit that is connected to a subsequent stage of the resistor and the switch to rectify an alternating-current voltage of the alternating-current power supply;

    a booster circuit to boost a direct-current voltage rectified by the rectifier circuit;

    a direct-current-voltage detector to detect a direct-current voltage output from the booster circuit;

    an alternating-current-voltage detector to detect an alternating-current voltage of the alternating-current power supply;

    a protection setter to calculate a first protection voltage on a basis of a boosting level by the booster circuit, calculate a second protection voltage on a basis of the alternating-current voltage detected by the alternating-current-voltage detector, compare the first protection voltage with the second protection voltage, and set either one of the first protection voltage and the second protection voltage as a protection voltage; and

    a controller to open the switch when the direct-current voltage falls below the protection voltage set by the protection setter and stop boosting performed by the booster circuit, whereinif the direct-current voltage falls below the protection voltage immediately after supply of an alternating-current voltage from the alternating-current power supply is stopped, the protection setter holds the protection voltage without changing the protection voltage and, after supply of the alternating-current voltage from the alternating-current power supply is started and a second transition period, which is a transition period of the direct-current voltage, passes, the protection setter changes setting of the protection voltage from the first protection voltage to the second protection voltage.

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