Fuel cell system and operation method thereof

2:

• The fuel cell system of claim 1, wherein said residual water volume estimation device estimates said residual water volume such that when said value of the total generated electrical energy is smaller than a third prescribed value, said residual water volume is estimated to be larger when said total generated electrical energy is larger, and when said value is larger than said third prescribed value and smaller than a first prescribed value, said residual water volume is estimated to be smaller when said total generated electrical energy is larger.

3:

• The fuel cell system of claim 1 or claim 2, wherein when said value of the total generated electrical energy exceeds the first prescribed value, said residual water volume estimation device takes said residual water volume to be substantially constant regardless of the value of said total generated electrical energy.

6:

• The fuel cell system of claim 5, wherein when said value of the total generated electrical energy exceeds the first prescribed value, said residual water content is taken to be substantially constant regardless of said value of the total generated electrical energy, and, when said value of the total generated electrical energy is larger than zero but smaller than a second prescribed value, said water/air purge process is not performed.

7:

• The fuel cell system of claim 1, further comprising:
• a warm-up process device that controls the generated electrical power of said fuel cell stack when said fuel cell system is started, and generates power for warm-up of said fuel cell stack corresponding to said value of the total generated electrical energy.

8:

• The fuel cell system of claim 7, wherein when said value of the total generated electrical energy is smaller than said third prescribed value, the generated electrical power is decreased corresponding to the rise in said total generated electrical energy, and when said value of the total generated electrical energy is larger than said third prescribed value, the generated electrical power is decreased corresponding to the rise in said total generated electrical energy.

9:

• The fuel cell system of claim 7 or claim 8, wherein when said value of the total generated electrical energy is larger than said first prescribed value higher than said third prescribed value, the generated electrical power is kept substantially constant independent of said total generated electrical energy.

10:

• The fuel cell system of claim 7, further comprising:
• a temperature detecting device for detecting the temperature of said fuel cell stack, such that the lower the fuel cell stack temperature at the start of power generation, the lower the maximum generated electrical power.

11:

• The fuel cell system of claim 1, wherein said value pertaining to the total generated electrical energy is any of the following values:
• the total generated electrical charge as the sum of the charge generated by the fuel cell stack from start-up of the fuel cell system, the hydrogen consumption quantity as the quantity of hydrogen consumed by the fuel cell system from start-up of the fuel cell system, the generated electrical power as the electrical power generated by the fuel cell stack from start-up of the fuel cell system, and the total generated water volume as the sum of the water volume generated by the fuel cell stack from start-up of the fuel cell system.

15:

• The fuel cell system of claim 14, wherein said estimating estimates said residual water volume such that when said value of the total generated electrical energy is smaller than a third prescribed value, said residual water volume is estimated to be larger when said total generated electrical energy is larger, and when said value is larger than said third prescribed value and smaller than a first prescribed value, said residual water volume is estimated to be smaller when said total generated electrical energy is larger.

16:

• The fuel cell system of claim 14 or claim 15, wherein when said value of the total generated electrical energy exceeds the first prescribed value, said estimating means takes said residual water volume to be substantially constant regardless of the value of said total generated electrical energy.

19:

• The fuel cell system of claim 18, wherein when said value of the total generated electrical energy exceeds the first prescribed value, said value is taken to be substantially constant regardless of said value of the total generated electrical energy, and, when said value of the total generated electrical energy is larger than said first prescribed value and smaller than a second prescribed value, said water/air purge process is not performed.

20:

• The fuel cell system of claim 14, further comprising:
• means for controlling the generated electrical power of said fuel cell stack means when said fuel cell system is started, and generating power for warm-up of said fuel cell stack means corresponding to said value of the total generated electrical energy.