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Fuel cell system

  • US 8,603,687 B2
  • Filed: 12/26/2008
  • Issued: 12/10/2013
  • Est. Priority Date: 12/28/2007
  • Status: Active Grant
First Claim
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1. A fuel cell system comprising:

  • a drive motor serving as a power source for driving a load and driven by electric power;

    a fuel cell generating electricity with electrochemical reaction of an oxidation gas containing oxygen to a fuel gas containing hydrogen and supplying the electric power to said drive motor;

    a first boost device boosting a voltage output from said fuel cell and enabling the post-boosting voltage to be supplied to said drive motor;

    a secondary battery capable of charging and discharging of the electric power and supplying the electric power to said drive motor with the discharge;

    a second boost device boosting a voltage output from said secondary battery and enabling the post-boosting voltage to be supplied to said drive motor; and

    a boost control unit controlling the voltage boost by said first boost device on the basis of a correlation between an output voltage of said fuel cell and a motor voltage necessary for driving said drive motor,wherein said boost control unit calculates output electric power of said fuel cell when driving said drive motor on the basis of the electric power supplied to the drive motor necessary for driving said drive motor, the electric power in the charge and the discharge of said secondary battery, the electric power that is lost when said first boost device boosts the output voltage of said fuel cell and the electric power that is lost when said second boost device boosts the output voltage of said secondary battery, and calculates output voltage of said fuel cell from the calculated output electric power of said fuel cell, andwherein said boost control unit conducts a control of the voltage boost by said first boost device, which is as to whether said drive motor is driven by the output voltage of said fuel cell or by a post-boosting voltage given after boosting said output of said fuel cell, based on a result of comparison between said output voltage of said fuel cell and the motor voltage necessary for driving said drive motor, andwherein said boost control unit, when the output voltage of said fuel cell is higher than the motor voltage of said drive motor, inhibits the output voltage of said fuel cell from being boosted by said first boost device and thus supplies the output voltage of said fuel cell directly to said drive motor, andwherein said boost control unit, when the output voltage of said fuel cell is not higher than the motor voltage of said drive motor, supplies the post-boosting voltage given after boosting said output voltage of said fuel cell by the first boost device to said drive motor.

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