Mehotd for determining a maximum power point voltage of a fuel cell, as well as fuel cell control system and power controller used in the fuel cell control system

A power controller used in a fuel cell control system, comprising at least:

• a voltage input terminal being capable of receiving an output voltage of a fuel cell;
• a control terminal for outputting a control signal to a control end of a power regulating means that regulates the output power of the fuel cell;
• a reference voltage generating source for generating a reference voltage;
• and
• a control signal generating means for comparing the output voltage of the fuel cell that is received at the voltage input terminal with the reference voltage generated by the reference voltage generating source, creating a control signal to limit the output power of the fuel cell so as to increase the output voltage of the fuel cell when the output voltage is lower than the reference voltage, and outputting the control signal to the control terminal;
• wherein:
• the reference voltage generated by the reference voltage generating source is set to a voltage equal to or higher than a maximum power point voltage when the fuel cell generates power at a maximum power point, the maximum power point voltage being assumed to be a minimum reference voltage;
• and
• a characteristic curve representing a current-voltage characteristic of the fuel cell is approximated by a prescribed approximating line within a range excluding an area in which an output voltage changes abruptly when an output current is nearly zero, an extrapolated voltage is obtained on an extension line of the prescribed approximating line at an output current of zero, and then the maximum power point voltage is determined from the extrapolated voltage.