Gas shortage preventive circuit for a fuel cell power generation system

A fuel cell power generation system for use with a load, comprising:

• a fuel cell having an output side;
• an inverting system connected to said output side of said fuel cell, said inverting system generating an inverting system output voltage which is supplied to the load;
• a constant voltage controlling circuit which generates a control signal that is supplied to said inverting system for controlling said inverting system output voltage, said constant voltage controlling circuit having a constant voltage setting unit which sets a target voltage, said constant voltage controlling circuit error-amplifying any deviation between said inverting system output voltage and said target voltage;
• a gas shortage preventive unit which includes
• an allowable overcurrent value calculating portion which calculates an allowable overcurrent value, said allowable overcurrent value being a function of a fuel utilization coefficient that is higher than a standard fuel utilization coefficient and an output current of said fuel cell, and
• a response speed controlling portion which eliminates any transient variation from the allowable overcurrent value and outputs it as an allowable overcurrent target value;
• and
• an overcurrent limiting unit which outputs a signal for reducing said target voltage of said constant voltage setting unit when the output current of said fuel cell exceeds the allowable overcurrent target value.