JP2003346849A - Power generation control device of fuel cell, and fuel cell system with the control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To continue the power generation of a fuel cell while preventing cells from being deteriorated when the voltage of the unit cell varies. <P>SOLUTION: This power generation control device 50 of the fuel cell 10 comprises means for: receiving a requested power generation power Pr from a main control part 40, a means for determining the minimum voltage cell between a plurality of cells 10a; estimating the IV characteristics of the minimum voltage cell from the minimum voltage Vo and output current IF of the cell; estimating the IV characteristics of the fuel cell 10 from the overall voltage Vs and output current IF of the plurality of cells; obtaining an upper limit output current I2 outputted by the minimum voltage cell at a specified lower limit voltage Vmin from the IV characteristics of the minimum voltage cell; obtaining a lower limit voltage generative power Q capable of being generated by the fuel cell 10 at the upper limit output current 12; and calculating a necessary oxygen flow amount and a necessary hydrogen flow amount for outputting the requested generation power Pr or the lower limit voltage generative power Q, whichever becomes smaller. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power generation control device used for a fuel cell system and a fuel cell system using the same.

[0002]

2. Description of the Related Art In a fuel cell, water is produced as a product because hydrogen and oxygen in the air are reacted as main fuels. The characteristics of the fuel cell sometimes changed temporarily due to the influence of the generated water. In particular, power generation may be hindered by freezing of water remaining in the fuel cell at the time of low-temperature start-up or freezing of water generated during power generation in a low-temperature environment.

In the case of a fuel cell having a stack structure in which a plurality of unit cells are stacked, the characteristics of the individual cells vary greatly due to the freezing of water generated during power generation. When the value of is increased, there is a problem that a unit cell having deteriorated characteristics is degraded by applying a reverse voltage, and the life is shortened.

Therefore, as described in Japanese Patent Application Laid-Open No. H11-34562, the voltage of each unit cell is usually detected, and when the voltage reaches a predetermined voltage or lower, the power generation of the fuel cell is immediately performed. To stop the system and stop the system.

[0005]

However, when the characteristics of the fuel cell change every moment due to internal freezing or repeatedly thaw due to generated heat, such as when starting from a low temperature, the amount of generated power is large. In some cases, the unit cells in the stack easily reach the set voltage or lower, and the system is frequently stopped.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a fuel cell that can continue power generation while preventing deterioration of a single battery cell when the voltage of the single battery cell varies.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a fuel cell (10) in which hydrogen and oxygen are supplied and a plurality of cells (10a) for power generation are stacked. A cell voltage detecting means (41) for detecting output voltages (V1 to Vn) of the plurality of cells (10a); and an output current (IF) of the fuel cell (10).
Current detecting means (12) for detecting the fuel cell;
0) A power generation control device for use in a fuel cell system including a main control unit (40) for performing power control, wherein the main control unit (40) requests generated power (Pr) for the fuel cell (10). ) As input values, and the plurality of cells (10a) from the output voltages (V1 to Vn) detected by the voltage detection means (41).
Means for determining the lowest voltage cell which outputs the lowest voltage (Vo), and the lowest output voltage (V
o) and a minimum voltage cell characteristic estimation for estimating a current-voltage characteristic indicating a relationship between an output voltage and an output current of the minimum voltage cell based on the output current (IF) detected by the current detection means (12). Means, and the plurality of cells (10
a) The total voltage (V) which is the sum of the output voltages (V1 to Vn)
s) and the output current (IF), the current-indicating the relationship between the output voltage and the output current of the fuel cell (10).
From the fuel cell characteristic estimating means for estimating the voltage characteristic and the current-voltage characteristic of the lowest voltage cell, when the output voltage (Vo) of the lowest voltage cell becomes a predetermined lower limit voltage (Vmin), the lowest voltage cell becomes Upper limit output current (I
Upper limit current determining means for obtaining 2), and lower limit voltage generating possible power calculating means for obtaining a lower limit voltage generating power (Q) which is a maximum power that the fuel cell (10) can generate in the upper limit output current (I2). And the required generated power (P
r) or a required oxygen flow rate calculating means for calculating an oxygen flow rate required to output the smaller of the lower limit voltage power generation possible power (Q), and the main control unit controls the oxygen flow rate as an output value corresponding to the input value. And an oxygen flow output means for outputting to the section (40).

As described above, when the required power generation (Pr) is input, the power that can be output by the fuel cell (10) is determined, and the required air flow rate for generating this power is set as the output value. Thus, the main control unit (40) can control the air flow rate of the air supply device (21) according to the required air flow rate. Thereby, the maximum power of the fuel cell (10) can be obtained within a range where the lowest voltage cell does not fall below the predetermined lower limit voltage (Vmin) (a range where the cell does not deteriorate), and power generation can be continued.

According to the second aspect of the present invention, a required hydrogen flow rate for calculating a hydrogen flow rate required to output the smaller of the required power (Pr) and the lower limit voltage power generation possible power (Q) Calculating means for calculating the flow rate of hydrogen as an output value with respect to the input value by the main control unit (4
0), and a hydrogen flow rate output means for outputting the result.

As described above, when the required generated power (Pr) is input, the required flow rate of hydrogen for generating power that can be output by the fuel cell (10) is set as the output value, so that the main control unit ( 40) can control the hydrogen flow rate of the hydrogen supply device (20) according to the required hydrogen flow rate.

Further, in the invention described in claim 3, the fuel cell system includes a hydrogen flow rate detecting means (22) for detecting a flow rate of hydrogen supplied to the fuel cell (10), and the fuel cell (10). ) For detecting the flow rate of the oxygen supplied to the oxygen flow rate detection means (23), and the hydrogen flow rate detected by the hydrogen flow rate detection means (22) and the oxygen flow rate detected by the oxygen flow rate detection means (23). Means for calculating gas flow power generation power (PI), which is the maximum power that the fuel cell (10) can generate in terms of flow rate, gas flow power generation power (PI) or lower limit voltage power generation power (Q), whichever is smaller, is the current power (Pf), which is the maximum power that the fuel cell (10) can generate at the oxygen flow rate and the hydrogen flow rate.
and c) present power generating power determining means, and current power generating power output means outputting current power generating power (Pfc) as an output value with respect to the input value to the main control unit (40).

As described above, when the required generated power (Pr) is input, the power (Pfc) that the fuel cell 10 can output at the current gas flow rate is determined, and this power (Pfc) is used as the output value. Thus, the main control unit (40) can control the power consumption of various devices to be within the maximum power (Pfc). Thereby, power generation can be continued without stopping the operation of the fuel cell (10).

[0013] The invention described in claim 4 is an invention of a fuel cell system.
The power generation control device according to any one of the first to third aspects is provided.

The reference numerals in the parentheses of the above means indicate the correspondence with the specific means described in the embodiments described later.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment to which the present invention is applied will be described below with reference to FIGS. In the present embodiment, the fuel cell system of the present invention is applied to an electric vehicle.

FIG. 1 shows the overall configuration of the fuel cell system according to the present embodiment. As shown in FIG. 1, the fuel cell system according to the present embodiment includes a fuel cell 10, a hydrogen supply device 2
0, air supply device 21, heating and cooling systems 30 to 35,
A main control unit 40, a sub control unit (power generation control device) 50, and the like are provided.

The fuel cell (FC stack) 10 generates electric power using an electrochemical reaction between hydrogen and oxygen. In this embodiment, a solid polymer electrolyte fuel cell is used as the fuel cell 10, and a plurality of cells serving as basic units are stacked. Each cell has a configuration in which an electrolyte membrane is sandwiched between a pair of electrodes. In the fuel cell 10, by supplying hydrogen and air (oxygen),
The following electrochemical reaction between hydrogen and oxygen occurs to generate electric energy. (Hydrogen electrode side) H ₂ → 2H ⁺ + 2e ⁻ (Oxygen electrode side) 2H ⁺ + 1 / 2O ₂ + 2e ⁻ → H ₂ O The electric power generated by the fuel cell 10 drives the traveling motor 11 via an inverter (not shown). Load power to
It is used for load power of auxiliary equipment for generating power in the fuel cell 10 or charging of a secondary battery (not shown). In the fuel cell system of the present embodiment, a current sensor 12 for detecting the output current of the fuel cell 10 is provided.

The hydrogen supply device 20 supplies hydrogen to the fuel cell 10 via a hydrogen supply path, and the air supply device 21 supplies oxygen-containing air to the fuel cell 10 via an air supply path. Is what you do. Hydrogen supply device 20
As, for example, a high-pressure hydrogen storage tank or a reformer that generates hydrogen by a reforming reaction can be used,
As the air supply device 21, for example, an air compressor that is an adiabatic compressor can be used.

The fuel cell system according to the present embodiment includes a hydrogen flow detecting device 22 for detecting a flow rate of hydrogen supplied from the hydrogen supply device 20 to the fuel cell 10, and an air supplied from the air supply device 21 to the fuel cell 10. An air flow rate detecting device 23 for detecting a flow rate is provided. The hydrogen flow detector 22 constitutes a hydrogen flow detector of the present invention, and the air flow detector 23 constitutes an oxygen flow detector of the present invention.

Further, it is necessary that the electrolyte membrane inside the fuel cell 10 contains moisture for a chemical reaction at the time of power generation. For this reason, hydrogen and air previously humidified by a humidifier (not shown) or the like are supplied to the fuel cell 10 so that the electrolyte membrane in the fuel cell 10 is humidified.

The heating / cooling system includes a heating medium circulation path 30 for circulating cooling water (heating medium) through the fuel cell 10,
Circulation pump 3 for circulating cooling water through heat medium circulation path 30
1. A radiator 32 for cooling the cooling water and a fan 33 for blowing air to the radiator 32 are provided. In the heating / cooling system, a heating heater 34 provided in parallel with the radiator 32 in the heating medium circulation path 30, a flow path switching valve (three-way valve) for switching the flow of cooling water to the radiator 32 or the heating heater 34. 35 is provided. As the heater 34, for example, an electric heater,
A combustion heater or the like can be used.

During normal operation, the cooling water flow path is switched by the flow path switching valve 35 so that the cooling water flows to the radiator 32 side. Thereby, the cooling water that has received the heat from the fuel cell 10 circulates through the heat medium circulation channel 30 to the radiator 32, exchanges heat with the outside air, and is cooled. As a result, the heat generated by the power generation in the fuel cell 10 is radiated, and the fuel cell 10 is kept at a constant temperature (for example, 8
(About 0 ° C.).

When the engine is started at a low temperature, the flow path of the cooling water is switched by the flow path switching valve 35 so that the cooling water flows toward the heater 34. Thereby, the cooling water heated by the heater 34 is supplied to the fuel cell 1 via the heat medium flow path 30.
0, and heats the fuel cell 10. As a result, the temperature of the fuel cell 10 can be raised to a temperature at which power can be generated.

The main control unit 40 controls various devices such as the traveling motor 11, the hydrogen supply device 20, the air supply device 21, the fan 33, the circulation pump 31, and the flow path switching valve 35. In addition, the main control unit 40 determines the load of the traveling motor 11 required for running the vehicle, the load of auxiliary equipment necessary for generating the fuel cell 10, and the load required for charging a secondary battery (not shown). In summary, the required load of the entire system is calculated as the required power generation Pr for the fuel cell 10. The required generated power Pr is output from the main control unit 40 to the sub control unit 50.

FIG. 2 shows the configuration of the sub control unit 50. As shown in FIG. 2, the sub control unit 40
A voltage detection circuit 51 for detecting an output voltage of each cell 10a, a current detection circuit 52 for detecting an output current of the fuel cell 10 from a sensor signal input from the current sensor 12,
An A / D conversion circuit 53 for converting an analog signal into a digital signal and a CPU 54 for performing various arithmetic processing are provided.

The voltage detecting circuit 51 constitutes the voltage detecting means of the present invention, and the current detecting circuit 52 and the current sensor 12 constitute the current detecting means of the present invention. The A / D conversion circuit 53 converts a hydrogen flow signal input from the hydrogen flow detection device 22 and an air flow signal input from the air flow detection device 23 into digital signals.

The sub-control unit 50 receives the required power Pr of the fuel cell 10 from the main control unit 40, and outputs, as an output signal corresponding to the input signal, a hydrogen flow rate and an air flow rate (hydrogen flow rate and air flow rate required for generating the required power generation) Oxygen flow) and the maximum power Pfc that the fuel cell 10 can currently generate.
Output to

Here, the relationship between the output of the fuel cell 10 and the gas supply amount will be described. FIG. 3 shows a single cell 1 constituting the fuel cell 10 when the gas supply amount changes.
0a shows IV characteristics (current-voltage characteristics). FIG.
100 shown by a solid line in the middle is an IV characteristic (IV basic characteristic) when hydrogen and oxygen are appropriately supplied together with the generated current, and 101 shown by a broken line is an insufficient supply of hydrogen and oxygen. It is an IV characteristic in the case. As shown in FIG. 3, it can be seen that when the gas supply amount is insufficient, the voltage sharply drops.

Next, the relationship between the output of the fuel cell 10 and the temperature change will be described. FIG. 4 shows the IV characteristics of the fuel cell unit cell 10a when the temperature changes. According to 200 → 201 → 202 → 203 in FIG.
The temperature at which the characteristics were measured is lower. As shown in FIG. 4, it can be seen that as the temperature decreases, the internal resistance of the cell 10a tends to increase and the voltage tends to decrease. Further, even when the cell 10a is half-frozen, power is generated in half the area, so that even if the current density is low in the entire cell area, the voltage is similarly reduced.

The operation of the sub-control unit 50 of the fuel cell system at a low temperature will be described below with reference to FIGS.
FIG. 5 is a characteristic diagram showing the IV characteristics of the fuel cell 10a, and FIG. 6 is a flowchart showing the operation of the sub control unit 50.

In FIG. 5, reference numeral 300 denotes the IV characteristic of the lowest voltage cell having the lowest output voltage, and reference numeral 301 denotes the average IV characteristic of the cell 10a constituting the fuel cell 10. The voltage of the entire fuel cell 10 is the voltage of the average IV characteristic 301 × the number of cells.

In the fuel cell 10 as a whole, the average IV characteristic 30
Generating power at the point where the maximum power is reached in 1 is advantageous in terms of early warm-up because the generated power increases and the amount of heat generated also increases. However, in the lowest voltage cell, the voltage is reduced and a reverse potential is applied, and the cell may be deteriorated. For this reason, the voltage of the lowest voltage cell is a predetermined lower limit voltage Vmin which is a voltage at which the cell is deteriorated due to a reverse voltage or the like.
It is necessary to generate the power of the fuel cell 10 within a range that does not fall below the range. The predetermined lower limit voltage Vmin can be set arbitrarily, and is set to 0.4 V in the present embodiment.

As shown in FIG. 6, first, the sub control unit 50
The vehicle request signal Pr transmitted from the main control unit 40 is received (S10). Next, the sub control unit 50 controls the voltage detection circuit 4
1, the voltage V1 of each cell 10a constituting the fuel cell 10
To Vn and the total voltage Vs which is the sum of the voltages of the cells 10
Is measured, and the current IF of the fuel cell 10 is measured by the current sensor 12 and the current detection circuit 42 (S11).

Next, the lowest voltage cell that outputs the lowest lowest voltage Vo is determined based on the voltages V1 to Vn of each cell 10a (S12).

Next, the hydrogen supply flow rate is measured by the hydrogen flow rate detection device 22, and the air supply flow rate is measured by the air flow rate detection device 23 (S13).

Next, the IV characteristic 300 of the lowest voltage cell that outputs the lowest output voltage Vo is estimated (S14). Since the IV characteristic 300 of the lowest voltage cell is considered to change in a similar manner to the IV basic characteristic 100 shown in FIG. 3, the IV characteristic 300 of the lowest voltage cell is obtained from the current IF, the minimum output voltage Vo, and the IV basic characteristic 100. 301 can be estimated.

Next, as in step S14, the total voltage V
The IV characteristic 301 of the fuel cell 10 is estimated from s and the IV basic characteristic 100 of FIG. 3 (S15). However, according to the IV characteristic 301 in FIG. 5, the average voltage value Vs /
n.

Next, the renewable power Pfc, the required hydrogen flow Hf, and the required air flow Af are calculated (S16), and are output to the main control unit 50 (S17). Generateable power Pf
c is the maximum power that the fuel cell 10 can generate without changing the current gas supply amount. The required hydrogen flow rate H
f and the required air flow rate Af are gas supply amounts required to generate the maximum power that the fuel cell 10 can generate with respect to the required power Pr.

Next, a method of calculating the renewable power Pfc, the required hydrogen flow Hf, and the required air flow Af will be described with reference to FIGS.
It will be described based on. FIG. 7 is a flowchart showing details of step S16 in FIG.

First, based on the IV characteristic 301 of the lowest voltage cell, an upper limit output current I2 that can output the lowest voltage cell is obtained (S1601). The upper limit output current I2 is a predetermined lower limit voltage Vmin at which the output voltage of the lowest voltage cell is determined in advance.
Is the maximum current that can be output within a range not less than.

Next, based on the IV characteristic 301 of the fuel cell 10, the lower limit voltage power generation possible power Q at which the fuel cell 10 can generate power at the upper limit output current I2 is obtained (S1602).

Next, the hydrogen upper limit current IH, which is the maximum current that can be generated at the current hydrogen flow rate obtained in step S13,
(S1603), and similarly, the air upper limit current Iair, which is the maximum current that can be generated at the current air flow rate, is determined (S1603).
1604). The hydrogen upper limit current IH can be calculated by IH [c / sec] = hydrogen flow rate [mol / sec] × 2 × 9600 [c / mol] × the number of cells n.
Iair [c / sec] = air flow rate [mol / sec] × 4 × 96
00 [c / mol] × (21/100) × the number of cells n.

Next, based on the IV characteristic 301 of the fuel cell 10, the hydrogen flow upper limit current IH or the air flow upper limit current I
The gas flow power generating power PI which is the maximum power that the fuel cell 10 can generate with the smaller of the air is determined (S
1605).

Next, the maximum power Pfc that the fuel cell 10 can currently output is calculated. The current power feasible power Pfc is determined by the smaller of the gas flow rate power feasible power PI and the lower limit voltage power feasible power Q (S1606).

Next, it is determined whether or not the required power generation Pr is smaller than the lower limit voltage power generation possible power Q (S1607).
As a result, the required generated power Pr is reduced to the lower limit voltage
If it is smaller, it can be determined that the lowest voltage cell does not reach the predetermined lower limit voltage Vmin even if the fuel cell 10 generates power up to Pr. In this case, the IV characteristic 3 in FIG.
01, a current value at which the electric power becomes Pr is specified, and a hydrogen supply amount Hf and an air supply amount Af required to generate this current
Is calculated (S1608).

On the other hand, if the required generated power Pr is larger than the lower limit voltage power Q, it can be determined that the fuel cell 10 can only generate power up to the lower limit voltage power Q. In this case, the current value at which the electric power becomes Q is specified on the IV characteristic 301 in FIG. 5, and the hydrogen supply amount Hf and the air supply amount Af required to generate this current are calculated (S
1609). Thereafter, the process returns to step S17 in FIG.

As described above, according to the present embodiment, the sub control unit 50
Indicates that the fuel cell 1
0 determines the power that can be output, and the required air flow rate for generating this power is used as the output value.
The air flow rate of the air supply device 21 can be controlled according to the required air flow rate. Thereby, the maximum power of the fuel cell 10 can be obtained within a range where the lowest voltage cell does not fall below the predetermined lower limit voltage Vmin (a range where the cell does not deteriorate), and power generation can be continued.

Similarly, since the sub-control unit 50 sets the output value to the required hydrogen flow rate for generating the power that can be output by the fuel cell 10, the main control unit 40 determines whether or not the hydrogen is supplied in accordance with the required hydrogen flow rate. The hydrogen flow rate of the device 20 can be controlled.

Further, the sub control unit 50 determines the required power generation Pr
Is input, the fuel cell 10 determines the power Pfc that can be output at the current gas flow rate, and uses this power Pfc as an output value. It is possible to control so that the sum of the power consumption of the equipment and the power required for charging the secondary battery is within the maximum power Pfc. Thereby, power generation can be continued without stopping the operation of the fuel cell 10.

Step S10 corresponds to input value receiving means, step S12 corresponds to lowest voltage cell determining means, step S14 corresponds to lowest voltage cell characteristic estimating means, and step S15 corresponds to fuel cell. Step S1601 corresponds to the upper limit current determining means, step S1602 corresponds to the lower limit voltage power generation possible power calculating means, and step S161 corresponds to the characteristic estimating means.
2. S1613 corresponds to the required oxygen flow rate calculating means and the required hydrogen flow rate calculating means, the above step S17 corresponds to the oxygen flow rate output means, the hydrogen flow rate output means, and the currently available power output means, and the step S1604 corresponds to the gas flow rate power generation means. Step S1606 corresponds to the current power generation possible power determination means.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing the overall configuration of a fuel cell system according to the embodiment.

FIG. 2 is a conceptual diagram illustrating a configuration of a sub control unit.

FIG. 3 is a characteristic diagram showing current-voltage characteristics of a fuel cell.

FIG. 4 is a characteristic diagram showing current-voltage characteristics of a fuel cell.

FIG. 5 is a characteristic diagram showing current-voltage characteristics of a fuel cell.

FIG. 6 is a flowchart showing processing contents of a sub control unit.

FIG. 7 is a flowchart showing the contents of a subroutine of FIG. 6;

[Explanation of symbols]

Reference Signs List 10: fuel cell (FC stack), 11: running motor, 12: current sensor, 20: hydrogen supply device, 21: air supply device, 22: hydrogen flow detection device, 23: air flow detection device, 30 to 35 Heating / cooling system, 40: Main control unit, 50: Sub-control unit (power generation control device).

Claims (4)

[Claims] 1. A fuel cell (10) in which hydrogen and oxygen are supplied and a plurality of cells (10a) for generating electricity are stacked.
The output voltage (V1 to V1) of each of the plurality of cells (10a)
Vn), a current detector (12) for detecting the output current (IF) of the fuel cell (10), and a main control for controlling the power of the fuel cell (10). A power generation control device for use in a fuel cell system including a unit (40), wherein an input value reception for receiving a required power generation (Pr) for the fuel cell (10) from the main control unit (40) as an input value. Means for determining the lowest voltage cell that outputs the lowest voltage (Vo) of the plurality of cells (10a) from the output voltages (V1 to Vn) detected by the voltage detection means (41). And the minimum output voltage (Vo) and the current detection means (12).
Minimum voltage cell characteristic estimating means for estimating a current-voltage characteristic indicating a relationship between an output voltage and an output current of the lowest voltage cell based on the output current (IF) detected by the plurality of cells (10a). A current-voltage characteristic showing a relationship between an output voltage and an output current of the fuel cell (10) based on a total voltage (Vs) which is a sum of output voltages (V1 to Vn) of the fuel cell and the output current (IF). From the fuel cell characteristic estimating means for estimating the current-voltage characteristic of the lowest voltage cell, the lowest voltage cell can be output when the output voltage (Vo) of the lowest voltage cell becomes a predetermined lower limit voltage (Vmin). An upper limit current determining means for obtaining an optimum upper limit output current (I2);
0) is a lower-limit voltage-generating power (Q) that is the maximum power that can be generated, and a lower-limit voltage-generating power (Q) that is smaller than the required power (Pr) or the lower-limit voltage-generating power (Q). A required oxygen flow rate calculating means for calculating an oxygen flow rate required to output the information, and an oxygen flow rate output means for outputting the oxygen flow rate to the main control unit (40) as an output value corresponding to the input value. Characteristic power generation control device. 2. A required hydrogen flow rate calculating means for calculating a hydrogen flow rate required to output a smaller one of the required power (Pr) and the lower limit voltage power generation possible power (Q), and an output corresponding to the input value. The power generation control device according to claim 1, further comprising: a hydrogen flow rate output unit configured to output the hydrogen flow rate as a value to the main control unit (40). 3. The fuel cell system according to claim 1, wherein said fuel cell system includes a hydrogen flow rate detecting means for detecting a flow rate of hydrogen supplied to said fuel cell, and a flow rate of oxygen supplied to said fuel cell. An oxygen flow rate detecting means (23) for detecting the fuel cell (10) at a hydrogen flow rate detected by the hydrogen flow rate detecting means (22) and an oxygen flow rate detected by the oxygen flow rate detecting means (23). Means for calculating a gas flow rate genable power (PI), which is the maximum power that can be generated, and either the gas flow rate genable power (PI) or the lower limit voltage genable power (Q), whichever is smaller. The current power (Pf), which is the maximum power that the fuel cell (10) can generate at the oxygen flow rate and the hydrogen flow rate,
c) presently generable power determining means, and current generable power output means for outputting the current generable power (Pfc) to the main control unit (40) as an output value with respect to the input value. Claim 1
Alternatively, the power generation control device according to claim 2. 4. A fuel cell system comprising the power generation control device according to claim 1. Description: