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POWER SUPPLY APPARATUS AND POWER CONTROL METHOD

  • US 20090243390A1
  • Filed: 02/26/2009
  • Published: 10/01/2009
  • Est. Priority Date: 03/25/2008
  • Status: Abandoned Application
First Claim
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1. A power supply apparatus comprising:

  • a DC to DC converter coupled to an output of a fuel cell, comprising a characteristic that an output voltage of the DC to DC converter drops in accordance with an increase of an output current of the DC to DC converter;

    a first diode connected between the output of the DC to DC converter and an output terminal of the apparatus;

    a second diode connected between an output of a secondary battery and the output terminal, the second diode comprising a forward voltage drop substantially equal to a forward voltage drop of the first diode;

    a first transistor comprising a current path connected in parallel with the first diode;

    a second transistor comprising a current path connected in parallel with the second diode; and

    a controller configured to monitor the output voltage of the DC to DC converter and the output voltage of the secondary battery, to set the first and the second transistor to the off and the on state respectively when the output voltage of the DC to DC converter is equal to or lower than a reference voltage which is the sum of the output voltage of the secondary battery and a given offset voltage, and to set the first and the second transistor to the on and the off state respectively when the output voltage of the DC to DC converter is higher than the reference voltage, the offset voltage being equal to the forward voltage drop or higher than the forward voltage drop by a given value.

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