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Switching power supply device

  • US 8,878,506 B2
  • Filed: 02/20/2012
  • Issued: 11/04/2014
  • Est. Priority Date: 06/02/2011
  • Status: Active Grant
First Claim
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1. A switching power supply device, comprising:

  • a chopper circuit that turns on/off the passage of a current to an inductor by means of a switching element; and

    a switching control circuit that switches the switching element so that an input voltage waveform and an input current waveform with respect to a phase of an input voltage become substantially similar in shape,wherein the switching control circuit is configured to switch the switching element at a switching frequency that is proportional to an input voltage dependent term of a formula that expresses a third harmonic component of ripples of the current flowing to the inductor, andwherein the formula is stated as
    Vfs=Vfs max*sin(3*π

    *(1

    V
    i/Vo)),Vfs min)where Vfs is a switching frequency control voltage, Vfs max is a voltage at a maximum oscillation frequency, Vfs min is a voltage at a minimum oscillation frequency, Vi is the input voltage, and Vo is an output voltage of the control circuit.

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