JP2003331891A - Fuel cell system, and starting method of fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently heat and humidify a fuel cell stack to reduce the start time of a fuel cell system, when starting the fuel cell system. <P>SOLUTION: This fuel cell system provided with a control part 18, a fuel cell stack 3, and current regulation parts 12 and 13 is used. The cell stack 3 is fed with an oxidation gas and a fuel gas. The regulation parts 12 and 13 are electrically connected to the cell stack 3. The control part 18 controls the regulation parts 12 and 13 so as to carry a stack current to the cell stack 3 when the cell stack 3 is heated. The stack current is a substantial constant current, or a stack current setting its ratio to the open circuit voltage of the cell stack 3 at a preset value. <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 fuel cell system and a fuel cell system start-up method, and more particularly to a fuel cell system and a fuel cell system start-up method for reducing the time required to start a fuel cell stack.

[0002]

2. Description of the Related Art An outline of a fuel cell system will be described with reference to FIG. FIG. 8 is a diagram showing a configuration of a conventional fuel cell system. The fuel cell system includes a fuel gas supply unit 10
1, oxidizing gas supply unit 102, fuel cell stack 103,
Heating unit 105, cooling unit 106, pump 107, diode 110, output switch 111, fuel gas flow control valve 1
16, an oxidizing gas flow rate control valve 117, and a control unit 118. Fuel gas supply unit 101-Fuel gas flow control valve 11
6- The fuel cell stack 103 includes the fuel gas pipe 152-
1 to 152-3 are connected. Oxidizing gas supply unit 10
2-Oxidizing Gas Flow Control Valve 117-Fuel Cell Stack 10
3 are connected by oxidizing gas pipes 153-1 to 153-3. The pump 107-heating unit 105-fuel cell stack 103-cooling unit 106 includes cooling water pipes 157-1 to 15-1.
57-4 are connected. Fuel cell stack 10
The 3-diode 110-output switch 111 is connected to the load device 104 by wiring 158-1 to 158-2. Then, power is supplied to the load device 104.

The fuel gas supply unit 101 supplies a fuel gas containing hydrogen (hydrogen-rich gas obtained by reforming hydrogen or methanol, gasoline, etc.) to the fuel cell stack 10.
Supply to 3. The fuel gas flow rate control valve 116 controls the flow rate of the fuel gas. The oxidizing gas supply unit 102 supplies an oxidizing gas (oxygen or air) that is a gas containing oxygen to the fuel cell stack 103. Oxidizing gas flow control valve 11
Reference numeral 7 controls the flow rate of the oxidizing gas. The fuel cell stack 103 uses a fuel gas and an oxidizing gas to generate electricity. Here, the fuel cell stack 103 includes not only a single stack but also a case where a plurality of stacks are connected in series and a case where they are connected in parallel. Heating unit 105
Heats the fuel cell stack 103 at the time of startup by heating water (hereinafter, cooling water) that is circulated as cooling water for the fuel cell stack 103 during normal operation. The cooling unit 106 cools the cooling water of the fuel cell stack 103 during normal operation. The pump 107 circulates cooling water among the fuel cell stack 103, the heater 105, and the cooler 106. The diode 110 limits the direction of the current from the fuel cell stack 103 to one direction. The output switch 111 turns ON / OFF the electrical connection between the fuel cell stack 103 and the load device 104.
/ OFF. The control unit 118 controls the above-mentioned units, valves and the like. In the case of the fuel cell system for a vehicle, the load device 104 is an inverter, a motor or the like for driving the vehicle. In the case of a stationary fuel cell system, it is a commercial inverter or the like.

In the polymer electrolyte fuel cell system, it is necessary to humidify the polymer membrane (electrolyte membrane) of the fuel cell at the time of startup. In addition, heating to the normal operating temperature (70 to 90 ° C) is required. Regarding humidification, the oxidizing gas and the fuel gas are humidified and supplied to humidify the electrolyte membrane.
For heating, the heating unit 105 warms the cooling water and circulates it through the fuel cell stack 103 to heat the fuel cell stack 103. In this case, in the heating unit 105, a method using an electric heater, a method using combustion heat of exhaust gas of the fuel cell stack 103 (mixed exhaust gas of the fuel gas pipe 152-3 and the oxidant gas pipe 153-3), and the like Thus, the heating unit 105 heats the cooling water.

The cooling water flows in the passage provided inside the separator of the fuel cell stack. The heat of the cooling water heats the fuel cell unit after heating the separator.
Therefore, there is a delay in transferring the heat of the cooling water to the fuel cell unit. Further, the fuel gas and the oxidizing gas are also heated and supplied, but since the amount of heat is small because they are gases, it takes time to heat the fuel cell stack. Further, the electrolyte membrane is humidified by the humidified fuel gas and oxidizing gas, but since the porous carbon material is used for the electrode portion and covers the entire surface of the electrolyte membrane, it takes time for the water vapor to reach the electrolyte membrane. It costs.

Fuel cell stacks for vehicles are expected to be as short as possible from startup to operation. A technique for shortening the startup time of a fuel cell system is desired. There is a demand for a technique for reducing the heating time of a fuel cell stack in a fuel cell system. There is a demand for a technique for shortening the humidification time of fuel cells in a fuel cell stack.

[0007]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a fuel cell system and a fuel cell system starting method capable of shortening the time required for starting.

Another object of the present invention is to provide a fuel cell system and a method of starting the fuel cell system, which can shorten the heating time of the fuel cell stack.

Still another object of the present invention is to provide a fuel cell system and a method of starting the fuel cell system, which can shorten the humidification time of the fuel cells in the fuel cell stack.

[0010]

[Means for Solving the Problems] Means for solving the problems will be described below by using the numbers and symbols used in the embodiments of the present invention. These numbers / codes are added in parentheses in order to clarify the correspondence between the description of [Claims] and the [Embodiment of the Invention]. However, those numbers and signs should not be used for the interpretation of the technical scope of the invention described in [Claims].

Therefore, in order to solve the above-mentioned problems, the fuel cell system of the present invention comprises a control unit (18), a fuel cell stack (3), and current adjusting units (12, 13 (13 ')).
/ 19, 20). Fuel cell stack (3)
Are supplied with oxidizing gas and fuel gas. The current adjusting unit (12, 13 (13 ') / 19, 20) is electrically connected to the fuel cell stack (3). Control unit (1
8) is a stack current (I) as a current flowing through the fuel cell stack (3) when heating the fuel cell stack (3).
s) so that the current adjusting unit (12, 13 (13 ') /
19, 20). Here, the fuel cell stack only needs to have one or more fuel battery cells, and does not necessarily have to have a plurality of fuel battery cells.

In the fuel cell system of the present invention, the stack current (Is) is substantially constant current (Ia).

Further, the fuel cell system of the present invention comprises a current sensor (9) for measuring a stack current (Is) and a stack voltage (V) as a voltage of the fuel cell stack (3).
and a voltage sensor (8) for measuring s). The control unit (18) controls the temperature (T) of the fuel cell stack (3).
And a stack voltage (Vs) and a stack current (Is) are associated with each other (FIG. 6). And the fuel cell stack (3) of the measured stack voltage (Vs)
Current adjusting unit (12, 13) so that the ratio of the open circuit voltage to the open circuit voltage becomes a stack current (Is) having a preset value.
(13 ') / 19, 20) is controlled.

Further, in the fuel cell system of the present invention, the current adjusting section (12, 13 (13 ')) is connected to the load (13 (1
3 ')) is included. Then, the current adjusting unit (12, 13 (1
3 ')) controls the size of the load (13 (13')) to adjust the stack current (Is).

Further, the fuel cell system of the present invention further comprises a first heating section (5) for heating water flowing in the fuel cell stack (3). The control unit (18) controls the first heating unit (5) so as to heat the fuel cell stack (3) by heating the stack current (Is) before heating the stack current (Is). To do.

Further, in the fuel cell system of the present invention, the load (13 (13 ')) is the second heating section (13') which heats the water based on the stack current (Is).

Further, in the fuel cell system of the present invention, the electric current converter (12, 13 (13 ') / 19, 20) converts the electric power characteristics of the fuel cell stack (3) into a power converter (19). And a secondary battery (20) charged by the converted electric power. Then, the control unit (18) controls the stack current (Is) with the power converter (19).

A method of starting a fuel cell system according to the present invention for solving the above-mentioned problems includes a step of supplying a fuel gas and an oxidizing gas to a fuel cell stack (3) and a temperature rise of the fuel cell stack (3). At this time, a step of flowing a stack current (Is) as a current through the fuel cell stack (3) is provided.

Further, in the method for starting the fuel cell system of the present invention, the step of causing the stack current (Is) to flow is such that the fuel cell stack (3) is brought to a preset first temperature or a preset first temperature. The step of raising the temperature for a period of time and, after the start of the temperature raising, from the preset second temperature or after the preset second time, the stack current (I
s) flowing.

Further, in the method of starting the fuel cell system according to the present invention, the step of causing the stack current (Is) to flow is such that the stack current (Is) is a preset constant current (Ia).

Further, in the starting method of the fuel cell system of the present invention, the step of causing the stack current (Is) to flow includes the stack current (Is) and the stack voltage (Vs) as the voltage of the fuel cell stack (3). Based on the temperature (T) of the fuel cell stack (3), the stack voltage (Vs) having a preset ratio to the open circuit voltage of the fuel cell stack (3) at the temperature (T). Changing the stack current (Is) to be a voltage.

A program relating to the present invention for solving the above-mentioned problems includes a step of supplying a fuel gas and an oxidizing gas to the fuel cell stack (3), and a step of supplying the fuel cell stack (3) up to a preset first temperature. , Or a step of raising the temperature for a preset first time, and after starting the raising of the temperature, from the preset second temperature or after the preset second time, the stack current (Is ) Is performed by the computer.

In the program according to the present invention, the step of causing the stack current (Is) to flow causes the computer to execute the above method in which the stack current (Is) is a preset constant current (Ia).

Further, in the program according to the present invention, the step of flowing the stack current (Is) is
s) and the stack voltage (Vs) as the voltage of the fuel cell stack (3), based on the fuel cell stack (3)
The temperature (T) of the stack and the stack voltage (V
changing the stack current (Is) such that s) is a voltage at a preset ratio to the open circuit voltage of the fuel cell stack (3) at temperature (T). Let the computer run.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a fuel cell system according to the present invention will be described below with reference to the accompanying drawings. In the present embodiment, a polymer electrolyte fuel cell system will be described as an example, but the present invention is also applicable to a system having other types of fuel cells. (In the respective embodiments, the same or corresponding parts will be described with the same reference numerals.)

(Embodiment 1) First, the configuration of the first embodiment of the fuel cell system of the present invention will be described. FIG. 1 is a diagram showing a configuration of a fuel cell system according to a first embodiment of the present invention. The fuel cell system includes a fuel gas supply unit 1, an oxidizing gas supply unit 2, a fuel cell stack 3, a heating unit 5, a cooling unit 6, a pump 7, a voltage sensor 8, a current sensor 9, a diode 10, an output switch 11, and discharge control. The unit 12, the discharge resistor 13, the second fuel gas flow rate control valve 14, the second oxidizing gas flow rate control valve 15, the first fuel gas flow rate control valve 16, the first oxidizing gas flow rate control valve 17, and the control unit 18. And connected to the load device 4,
Electric power is supplied to the load device 4. Then, the first fuel gas pipes 52-1 to 52-3 and the second fuel gas pipes 54-1 to 54-2 which are pipes for fuel gas, and the first oxidizing gas pipe 53-1 which is a pipe for oxidizing gas ~ 53-3 and the second
It has oxidizing gas pipes 55-1 to 55-2, an exhaust pipe 56, and cooling water pipes 57-1 to 57-4 which are pipes for cooling water. In addition, wirings 58-1 to 58- that are wirings for electricity
2, wirings 59-1 to 59-2 for the discharge control unit 12, and wirings 61-1 to 61-2 for the discharge resistance 13.

The fuel gas supply unit 1 has a reforming unit, a CO
Metamorphic section, humidification section (However, in the case of steam reforming, the reformed gas has already been humidified in the process, so no humidification section is required)
Have. The fuel gas A is supplied to the fuel electrode 32 (described later) of the fuel cell stack 3 via the first fuel gas pipe 52-1, the first fuel gas flow rate control valve 16 and the first fuel gas pipe 52-2. Here, the fuel gas A is a gas containing hydrogen, which is exemplified by hydrogen or a hydrogen-rich gas obtained by reforming a hydrocarbon-based material such as methanol or methane, and the CO concentration is less than a predetermined amount, It is humidified. Further, the fuel gas supply unit 1 supplies the fuel gas B to the heating unit 5 via the second fuel gas pipe 54-1, the second fuel gas flow rate control valve 14 and the second fuel gas pipe 54-2. Here, the fuel gas B is a fuel that is a raw material of the fuel gas A, and is not humidified or reformed.

The oxidizing gas supply section 2 has a humidifying section inside. The oxidizing gas A is supplied to the oxygen electrode 33 (described later) of the fuel cell stack 3 via the first oxidizing gas pipe 53-1, the first oxidizing gas flow rate control valve 17 and the first oxidizing gas pipe 53-2. Here, the oxidizing gas A is a gas containing oxygen or oxygen exemplified by air, and is humidified. In addition, the oxidizing gas supply unit 2 supplies the oxidizing gas B to the heating unit 5 via the second oxidizing gas pipe 55-1, the second oxidizing gas flow rate control valve 15 and the second oxidizing gas pipe 55-2. Here, the oxidizing gas B is an oxidizing gas that is a raw material of the oxidizing gas A and is not humidified.

The fuel cell stack 3 is an assembly of fuel cell units (one fuel cell unit or a stack of a plurality of fuel cell units connected in series) for generating electric power using hydrogen in the fuel gas A and oxygen in the oxidizing gas. Is. Details will be described later. Here, the fuel cell stack 3 is not limited to a single stack,
There are cases where a plurality of stacks are connected in series (the output voltage can be increased) and cases where they are connected in parallel (the output current can be increased). Further, as the fuel cell, a phosphoric acid type, a molten carbonate type, a solid oxide type or the like can be used in addition to the solid polymer type.

The heating unit 5 is supplied with water (cooling water) that circulates to cool the fuel cell stack 3 during normal operation at the time of startup via the cooling water pipe 57-1 to heat the fuel cell stack 3. To heat up. Then, the heated cooling water is supplied to the fuel cell stack 3 via the cooling water pipe 57-2. When heating, fuel gas supply unit 1
From the second fuel gas pipe 54-1, the second fuel gas flow rate control valve 14 and the second fuel gas pipe 54-2. At the same time, from the oxidizing gas supply unit 2,
Second oxidizing gas pipe 55-1-Second oxidizing gas flow control valve 1
The oxidant gas B is supplied through the 5-second oxidant gas pipe 55-2. The fuel gas B and the oxidizing gas B are burned, and heating is performed by the heat. The exhaust gas after combustion is discharged from the exhaust pipe 56. The heating is not performed except when the fuel cell stack 3 is started.

The cooling unit 6 cools the cooling water heated by passing through the fuel cell stack 3 during the normal operation.
-3, and is cooled by a method such as heat exchange. Then, the cooled cooling water is sent to the pump 7 via the cooling water pipe 57-4. When the fuel cell stack 3 is activated, it is not cooled.

The pump 7 is supplied with the cooled cooling water from the cooling water pipe 57-4 and discharges it to the cooling water pipe 57-1. Cooling water is supplied from the pump 7 to the cooling water pipe 57-1.
It is circulated in the order of pump 7-heating unit 5-fuel cell stack 3-cooling unit 6-pump 7 via 57-4.

The voltage sensor 8 measures the stack voltage Vs which is the voltage of the fuel cell stack 3. One terminal,
Wiring 58-1 for extracting electric power from the fuel cell stack 3
Further, the other terminal is connected to the wiring 58-2. The measured stack voltage Vs is output to the discharge controller 12. The current sensor 9 measures the stack current Is, which is the current of the fuel cell stack 3. It is connected in series in the middle of the wiring 58-1. The measured stack current Is is output to the discharge controller 12.

The diode 10 limits the direction of the current from the fuel cell stack 3 to one direction. It is connected in series in the middle of the wiring 58-1. The output switch 11 turns ON / OFF the electrical connection between the fuel cell stack 3 and the load device 4 by turning the switch ON / OFF. At startup, O
It is FF.

The discharge controller 12, which is one of the components of the power controller, determines the magnitude of the stack current Is of the fuel cell stack 3 based on the stack voltage Vs, the stack current Is, and the command from the controller 18. In order to control, the magnitude of the load of the discharge resistance 13 electrically connected to the fuel cell stack 3 is controlled (when the discharge resistance is variable and the stack current Is is large, the discharge resistance 13 is small, When decreasing the current Is, the discharge resistance is increased). Alternatively, a method may be used in which the size of the discharge resistor 13 is fixed and the discharge current is controlled by a chopper or the like. One terminal is connected to the point a between the output switch 11 and the fuel cell stack 3 of the wiring 58-1 for extracting electric power from the fuel cell stack 3, and the other terminal is connected to the point b of the wiring 58-2. . The discharge resistor 13 as one load in the configuration of the power adjustment unit controls the magnitude of the load by the discharge control unit 12 and consumes the power generated by the fuel cell unit.

The second fuel gas flow rate control valve 14 is located between the second fuel gas pipe 54-1 and the second fuel gas pipe 54-2, and is the fuel gas supplied from the fuel gas supply unit 1 to the heating unit 5. The flow rate (supply amount) of B is controlled. The first fuel gas flow rate control valve 16 is located between the first fuel gas pipe 52-1 and the first fuel gas pipe 52-2, and controls the fuel gas A supplied from the fuel gas supply unit 1 to the fuel cell stack 3. Flow rate (supply amount)
To control.

The second oxidant gas flow control valve 15 is located between the second oxidant gas pipe 55-1 and the second oxidant gas pipe 55-2, and oxidant gas supplied from the oxidant gas supply unit 2 to the heating unit 5 is supplied. The flow rate (supply amount) of B is controlled. The first oxidizing gas flow control valve 17 is located between the first oxidizing gas pipe 53-1 and the first oxidizing gas pipe 53-2, and controls the oxidizing gas A supplied from the oxidizing gas supply unit 2 to the fuel cell stack 3. Flow rate (supply amount)
To control.

The control unit 18 controls the entire fuel cell system (fuel gas supply unit 1, oxidizing gas supply unit 2, fuel cell stack 3, heating unit 5, cooling unit 6, pump 7, voltage sensor 8, current sensor 9, diode). 10, output switch 11, discharge control unit 12 (discharge resistance 13), second fuel gas flow rate control valve 14, second oxidizing gas flow rate control valve 15, first fuel gas flow rate control valve 16, first oxidizing gas flow rate control valve (Including 17).

In the case of a vehicle fuel cell system, the load device 4 is an inverter, a motor or the like for driving the vehicle.
In the case of a stationary fuel cell system, it is a commercial inverter or the like.

Next, the fuel cell will be described with reference to FIG. FIG. 2 is a cross-sectional view illustrating the fuel cell 30 and the separator 34. The polymer electrolyte fuel cell includes, as a basic structure, two separators 34 and a fuel battery cell 30 sandwiched between them.

The fuel cell 30 has a fuel electrode 32, an oxygen electrode 33, and an electrolyte membrane 31. The electrolyte membrane 31 is sandwiched between a fuel electrode 32 and an oxygen electrode 33, and the hydrogen in the fuel gas A and the oxygen in the oxidizing gas A supplied via these electrodes are used to generate electricity by an electrochemical reaction (cell reaction). To do. The electrolyte membrane 31 is exemplified by a membrane of ion exchange resin such as a perfluorosulfonic acid membrane. Fuel electrode 32 and oxygen electrode 3
3 circulates the fuel gas and the oxidizing gas, and mediates the electrochemical reaction between hydrogen in the fuel gas and oxygen in the oxidizing gas. It is also a passage for electrons accompanying the battery reaction. The fuel electrode 32 and the oxygen electrode 33 include a current collecting layer for taking out the generated electric power and a reaction layer (catalyst layer) involved in the cell reaction.

The separator 34 supplies a fuel gas passage 35 for supplying the fuel gas A to the fuel electrode 32 of the fuel cell 30 on one surface and an oxidizing gas to the oxygen electrode 33 of the fuel cell 30 on the other surface. And an oxidizing gas passage 36. Further, it has a cooling water passage 37 which is provided between the fuel gas passage 35 and the oxidizing gas passage 36 and supplies cooling water for cooling the fuel cell stack 3 (heating at the time of startup). Further, the fuel cells 30 are electrically joined together. The separator 34 is exemplified by a carbon (graphite) composite.

Next, the structure of the fuel cell stack will be described with reference to FIG. FIG. 3 is a perspective view showing the configuration of the fuel cell stack 3. The fuel cell stack 3 includes separators 34-1 to 34-n (n is a natural number of 2 or more, the same applies hereinafter), fuel cell units 30-1 to 30-n-1, a power generation section 39, a current collecting plate 40, an insulating plate. 41, end plate 42, current collecting plate 46, insulating plate 47, end plate 48, fuel gas inlet 43, cooling water inlet 44, oxidizing gas inlet 45, oxidizing gas outlet 49, cooling water outlet 50, fuel A gas outlet 51 is provided.

The power generation section 39 is a section for generating power in the fuel cell stack 3, and is the fuel cell 30-s (s
= 1 to n-1, a natural number, the same applies hereinafter) is the separator 34
They are connected in series via -r (r = s and r = s + 1). Separator 34-r (r = s and r = s + 1)
Are arranged on both sides of the fuel battery cells 30-s and electrically connect adjacent fuel battery cells 30 to each other. The separator 34-r and the fuel cell 30-s are as described in FIG.

Current collecting plate 40 and current collecting plate 46
Is an electrode for collecting the electric power generated by the fuel cells 30-1 to 30-n-1 and taking it to the outside. The insulating plate 41 and the insulating plate 47 are the current collecting plate 4
0 and the current collecting plate 46 are insulated from the end plate 42 and the end plate 48. The end plate 42 and the end plate 48 sandwich the power generation unit 39 from both sides. Further, the fuel gas inlet 4 is provided in the end plate 42.
3, a cooling water inlet 44 and an oxidizing gas inlet 45 are provided. Fuel gas to the fuel cell stack 3,
Supply cooling water and oxidizing gas. Similarly, the end plate 48 is provided with an oxidizing gas outlet 49, a cooling water outlet 50, and a fuel gas outlet 51. Oxidizing gas, cooling water, and fuel gas are discharged from the fuel cell stack 3, respectively.

Next, the operation (starting method of the fuel cell system) in the first embodiment of the fuel cell system according to the present invention will be described with reference to FIGS. 1, 6 and 7.

First, FIGS. 6 and 7 will be described. FIG. 6 is a diagram showing the relationship between the stack voltage Vs and the stack current Is of the fuel cell stack 3. The horizontal axis represents the stack current Is and the vertical axis represents the stack voltage Vs. Curve D1
To D4 are different temperatures T _{1 to} T ₄ (T ₁ > T ₂ >).
T _3> is an Is-Vs curve in _{T 4).} V ₀₁ ~
V ₀₄ is an open circuit voltage in each case of the curves D1 to D4 (temperatures T _{1 to} T ₄ ). The points a1 to a4 are
The points are the stack current Is = Ia (constant current) in each of the curves D1 to D4 (temperatures T _{1 to} T ₄ ). Vs points b1 to b4 are curves D1 to D4 (temperature T ₁
To T ₄ ) in each case, a fixed ratio (eg, 70%, stack voltage Vs of b1 = Vs =) to the open circuit voltage.
It has a stack voltage Vs of 0.7 × V ₀₁ ). V _E is the minimum value (allowable range) of the stack voltage Vs when the stack current Is is passed. The (stack current Is, stack voltage Vs) at each point is (Ia, Vs (a1)) to (Ia, Vs (a) at points a1 to a4.
4)), at points b1 to b4, (Is (b1), Vs
(B1)) to (Is (b4), Vs (b4)).

FIG. 7 is a timing chart showing the operation at the time of starting the fuel cell system. Here, (a) the relationship between the temperature of the fuel cell stack 3 and time, (b) the heating unit 5
Between the fuel gas B supplied to the heating unit 5, (c) the relationship between the oxidizing gas B supplied to the heating unit 5 and the time, and (d) the fuel gas A supplied to the fuel cell stack 3 and the time. (E) Oxidizing gas A supplied to the fuel cell stack 3
And (f) the relationship between stack current Is, which is the output current of the fuel cell stack 3, and time. The vertical axis represents (a) the temperature of the fuel cell stack 3, (b).
The flow rate of the fuel gas B, (c) flow rate of the oxidizing gas B, (d) flow rate of the fuel gas A, (e) flow rate of the oxidizing gas A, (f) current Is, and the horizontal axis is time. The present invention is
It is not limited to the timing chart of FIG.

Each temperature T of the fuel cell stack 3 as shown in FIG.
The data (table) indicating the relationship between the stack voltage Vs and the stack current Is in the above is stored in the storage unit (not shown) of the control unit 18 for each combination of the flow rates of the fuel gas A and the oxidizing gas B, and the control unit Used for control of 18. Further, the data showing the timing chart as shown in FIG.
The control unit 1 is stored in a storage unit (not shown) of the control unit 18.
8 is used for control.

The operation will be described below. In this embodiment, methane gas is used as the raw fuel gas that is the raw material of the fuel gas, and air is used as the oxidizing gas.

(1) Step S01 (Time 0) The fuel gas supply unit 1 is in a state capable of supplying methane gas as the fuel gas B. However, it is not in a state where the methane gas is reformed in the reforming section, CO is removed to a low concentration or less in the CO shift conversion section, and water vapor can be added (humidification) in the humidification section. That is, the fuel gas A is not ready yet.
At this time, the flow rate of the fuel gas B (FIG. 7B) = 0, and the flow rate of the fuel gas A (FIG. 7D) = 0.

The oxidizing gas supply unit 2 is in a state in which air can be supplied as the oxidizing gas B. However, the steam cannot be added (humidified) in the humidifying section. That is, the oxidizing gas A is not yet ready. At this time, the oxidizing gas B flow rate (FIG. 7C) = 0, the oxidizing gas A flow rate (FIG. 7E)
= 0.

Line for circulating cooling water (cooling water pipe 57
No cooling water is circulated in the cooling water circulation lines (-1 to 57-4, hereinafter referred to as cooling water circulation line). The temperature of the heating part 5 is room temperature.

The fuel cell stack 3 has a temperature T (see FIG.
(A)) = room temperature (RT), stack current Is (FIG. 7)
(F)) = 0. Output switch 11, discharge control unit 1
2 is an OFF state.

[0055] (2) Step S02 (time _{0 to t} 1) the user or the like, the fuel cell system to ON. The control unit 18 starts the activation of the fuel cell system. Control unit 1
Under the control of the second fuel gas flow rate control valve 8, 8 supplies methane gas as the fuel gas B from the fuel gas supply section 1 to the heating section 5 at a flow rate Q ₁₀ . At the same time, the fuel gas supply unit 1 is controlled to activate the reforming unit, the CO shift conversion unit, and the humidification unit. However, the fuel gas A is not prepared yet, so the fuel gas A is not supplied to the fuel cell stack 3. At this time, the fuel gas B flow rate (FIG. 7B) = Q ₁₀ and the fuel gas A flow rate (FIG. 7D) = 0.

The control section 18 includes the second oxidizing gas flow rate control valve 1
Under the control of No. 5, air is supplied from the oxidizing gas supply unit 2 as the oxidizing gas B to the heating unit 5 at a flow rate P ₁₀ . However, the oxidizing gas A is not supplied to the fuel cell stack 3 until the preparation of the fuel gas A is completed. At this time, the oxidizing gas B
Flow rate (FIG. 7C) = P ₁₀ , flow rate of oxidizing gas A (FIG. 7)
(E)) = 0.

The controller 18 activates the pump 7 to circulate the cooling water in the cooling water circulation line at a constant flow rate. At the same time, the heating unit 5 that receives the supply of the fuel gas B and the oxidizing gas B is started. In the heating unit 5, the cooling water is heated by the combustion of the fuel gas B and the oxidizing gas B at a constant flow rate. Then, the heated cooling water circulates in the cooling water circulation line.

The fuel cell stack 3 is gradually heated by the supply of heated cooling water. The temperature T gradually increases from room temperature (RT) (FIG. 7 (a)). The stack current Is (FIG. 7 (f)) = 0. The output switch 11 and the discharge control unit 12 are in the OFF state.

(3) Step S03 (time t _{1 to} t ₂ ) The control section 18 controls the second fuel gas flow rate control valve 14 to transfer the methane gas as the fuel gas B to the heating section 5. , And the flow rate is Q ₁₀ . at the same time,
Since the preparation of the fuel gas A in the fuel gas supply unit 1 is completed, the control unit 18 controls the fuel gas supply unit 1 to supply the fuel gas A to the fuel cell stack 3 under the control of the first fuel gas flow rate control valve 16. Supply to the fuel electrode 32. At that time, the flow rate is gradually increased, finally to Q _20. At this time, the fuel gas B flow rate (FIG. 7 (b)) = Q ₁₀ and the fuel gas A flow rate (FIG. 7 (d)) = 0 to Q ₂₀ .

The control unit 18 includes the second oxidizing gas flow rate control valve 1
Under the control of No. 5, air is supplied from the oxidizing gas supply unit 2 as the oxidizing gas B to the heating unit 5 at a flow rate P ₁₀ . At the same time, when the supply of the fuel gas A is started (preparation of the oxidizing gas A in the oxidizing gas supply unit 2 is completed earlier than preparation of the fuel gas A), by the control of the first oxidizing gas flow rate control valve 17, The oxidizing gas supply unit 2 supplies the oxidizing gas A to the oxygen electrode 33 of the fuel cell stack 3. At that time, the flow rate is gradually increased to finally reach P ₂₀ . At this time, the oxidizing gas B flow rate (FIG. 7C) = P ₁₀ and the oxidizing gas A flow rate (FIG. 7E) = 0 to P ₂₀ .

The control unit 18 causes the pump 7 to operate in a steady state,
Cooling water is constantly circulated in the cooling water circulation line.
Further, in the heating section 5, the fuel gas B and the oxidizing gas B are supplied at a constant flow rate, and the cooling water is heated with a constant heat. The heated cooling water circulates in the cooling water circulation line.

The fuel cell stack 3 is gradually heated by the supply of heated cooling water. Further, the humidified fuel gas A and the humidified oxidizing gas B are supplied to humidify the electrolyte membrane 31. The temperature T gradually increases from room temperature (RT) (FIG. 7).
(A)). The stack current Is (FIG. 7 (f)) = 0. The output switch 11 and the discharge control unit 12 are in the OFF state.

[0063] (4) Step S04 (time _t 2 _~t 3) control unit 18, under the control of the first fuel gas flow control valve 16, the fuel gas supply unit 1, the fuel gas A at a constant flow rate, the fuel It is supplied to the battery stack 3. At this time, the flow rate of the fuel gas B (FIG. 7 (b)) = Q ₁₀ and the flow rate of the fuel gas A (FIG. 7 (d)) = Q ₂₀ .

The control unit 18 includes the first oxidizing gas flow rate control valve 1
By the control of 7, the oxidizing gas supply unit 2 supplies the oxidizing gas A to the fuel cell stack 3 at a constant flow rate. At this time, the flow rate of the oxidizing gas B (FIG. 7C) = P ₁₀ and the flow rate of the oxidizing gas A (FIG. 7E) = P ₂₀ .

The control unit 18 causes the pump 7 to perform a steady operation,
Cooling water is constantly circulated in the cooling water circulation line.
The fuel cell stack 3 is heated by the cooling water heated by the heating unit 5 and the fuel gas A and the oxidizing gas A heated to the operating temperature (target temperature) T ₀ of the fuel cell stack, increasing the temperature rising rate, Continue to raise the temperature.

The fuel cell stack 3 is supplied with the fuel gas A and the oxidizing gas A, and the electrolyte membrane 31 is heated and humidified to a state where power generation with a small stack current Is is possible. However, the temperature and humidification levels required for normal power generation have not been reached. That is, the temperature rise and humidification are insufficient. Then, the control unit 18 controls the discharge control unit 12 to generate power in the fuel cell stack 3. The fuel cell stack 3 is heated by the heat of the power generation. Temperature T
Further increases the temperature rising rate, becomes higher, and finally becomes T ₀ of the operating temperature (target temperature) of the fuel cell stack (FIG. 7).
(A)). At that time, water is generated on the electrolyte membrane 31 by power generation. As a result, the electrolyte membrane 31 is humidified. That is, not only the humidification by the fuel gas A and the oxidizing gas A but also the generated water is humidified, and the humidification is in a sufficient state.

The discharge controller 12 causes the stack current Is to flow to the discharge resistor 13. The stack current Is is then consumed by the discharge. The output switch 11 is in the OFF state.

As a method of power generation, for example, there are a method of setting the stack current Is as a (substantially) constant current Ia, and a method of setting the stack current Is as a stack voltage Vs having a constant ratio to the open circuit voltage. The stack voltage Vs is measured by the voltage sensor 8 and the stack current Is is measured by the current sensor 9. However, “substantially” means including an error in the device configuration.

(I) When the stack current Is is a (substantially) constant current Ia (i) The discharge controller 12 controls the temperature T indicating the open circuit voltage V _{04.
At 4} (however, at time t ₂ ), the constant current Ia is controlled to flow. That is, the fuel cell stack 3 is connected to the discharge resistor 1
Connect to 3. Then, the value of the stack current Is is gradually increased by gradually increasing the magnitude of the load of the discharge resistor 13 to set the stack current Is = Ia (point a4). At that time, the stack voltage Vs is prevented from _falling below a preset allowable range V _E. (Ii) The temperature of the fuel cell stack 3 gradually rises due to power generation, and the open circuit voltage gradually increases (V ₀₄ → V
₀₃ → V ₀₂ → V ₀₁ ). In accordance therewith, the discharge control unit 12 gradually reduces the load of the discharge resistor 13 so that the current Ia is always constant (point a4 → point a3 → point a2 → point a1). The stack voltage Vs is continuously output to the control unit 18. (Iii) When the curve D1 (temperature T ₁ ) is the Is-Vs curve at the operating temperature T ₀ (T ₁ = T ₀ ), and the stack voltage Vs (a1) at the point a1 is reached, the control unit is reached. 18
Stops the power generation by the discharge control unit 12.

(II) When the stack current Is is set to the stack current Is which becomes the stack voltage Vs at a constant rate (here, 70%) with respect to the open circuit voltage (i) The discharge controller 12 opens the open circuit voltage V _04. Indicating temperature T
₄ (however, at time t ₂ ) the stack voltage Vs
(B4) = 0.7 × V ₀₄ Stack current Is (b
4) Flow control is performed. That is, the fuel cell stack 3
Is connected to the discharge resistor 13. Then, the discharge resistance 13
By gradually increasing the size of the load of the stack current Is, the value of the stack current Is is gradually increased, and the stack current Is is increased.
= Is (b4) (point b4). At that time, the stack voltage Vs (b4) is prevented from _falling below a preset allowable range V _E. (Ii) The temperature of the fuel cell stack 3 gradually rises due to power generation, and the open circuit voltage gradually increases (V ₀₄ → V
₀₃ → V ₀₂ → V ₀₁ ). Accordingly, the discharge control unit 12 gradually increases the load of the discharge resistor 13 (Is (b4) → Is (b3) → Is (b2) → Is.
(B1)) so that the stack current Is has a constant ratio (70%) to the open circuit voltage (point b4 → point b3).
→ point b2 → point b1). The stack voltage Vs is continuously
It is output to the control unit 18. (Iii) When the curve D1 (temperature T ₁ ) is the Is-Vs curve at the operating temperature T ₀ (T ₁ = T ₀ ), the stack voltage Vs (b1) at the point b1 (or the stack current Is (b)
1)), the control unit 18 determines that the discharge control unit 1
Power generation by 2 is stopped.

[0071] (5) Step S05 (time _t 3 ~) control unit 18, closes the second fuel gas flow control valve 14,
The flow rate of the fuel gas B supplied from the fuel gas supply unit 1 to the heating unit 5 is zero. At the same time, the control unit 18 controls the first fuel gas flow rate control valve 16 to control the fuel gas from the fuel gas supply unit 1.
The fuel gas A is supplied to the fuel cell stack 3 at a constant flow rate. The flow rate may be changed depending on the operating conditions of the fuel cell stack 3. At this time, the flow rate of the fuel gas B (see FIG.
(B)) = 0, fuel gas A flow rate (FIG. 7 (d)) = Q ₂₀
(Can be changed).

The control unit 18 uses the second oxidizing gas flow rate control valve 1
5 is closed, and the flow rate of the oxidizing gas B supplied from the oxidizing gas supply unit 2 to the heating unit 5 is set to 0. At the same time, the control unit 18
By the control of the first oxidizing gas flow rate control valve 17, the oxidizing gas supply unit 2 supplies the oxidizing gas A to the fuel cell stack 3 at a constant flow rate. The flow rate may be changed depending on the operating conditions of the fuel cell stack 3. At this time, the oxidizing gas B
Flow rate (FIG. 7C) = 0, oxidizing gas A flow rate (FIG. 7C)
(E)) = P ₂₀ (changeable).

The control unit 18 causes the pump 7 to operate in a steady state,
Cooling water is constantly circulated in the cooling water circulation line.
Further, in the heating section 5, the flow rates of the fuel gas B and the oxidizing gas B are both 0, and heating is not performed. Then, the cooling unit 6 is turned on to start cooling the cooling water in the cooling unit 6. The cooling water circulates in the cooling water circulation line.

The fuel cell stack 3 has an operating temperature T ₀ and the electrolyte membrane 31 is sufficiently humidified. Control unit 18
Turns off the discharge control unit 12 and turns on the output switch 11 to start the supply of the electric power of the fuel cell stack 3 to the load device 4. Fuel cell stack 3
The heat generated by the power generation is carried away by the cooling water. The control unit 18 adjusts the discharge amount of the pump 7 and the cooling capacity of the cooling unit 6 depending on the amount of heat generated (detected by the water temperature of the cooling water after passing through the fuel cell stack 3). The temperature T is maintained at the operating temperature T ₀ of the fuel cell stack 3 (see FIG. 7).
(A)).

With the above steps S01 to S04, the startup of the fuel cell system is completed. Then, as in step S05, a normal operating state is established.

In this embodiment, as a method of power generation, for example, the stack current Is is set to a (substantially) constant current Ia, and the stack voltage V at a constant ratio to the open circuit voltage.
However, the present invention is not limited to these methods.

In the present embodiment, one fuel gas A and oxidation
Gas A flow rate combination (Q₂₀, P ₂₀) Against
I am in control. However, the data table as shown in Figure 6
Using the data for each flow rate of, for example, the stack current I
As a result, the specified fuel utilization rate (and air utilization
Flow rate of fuel gas A (and oxidizing gas A)
It is also possible to perform control to change the. In this case,
Since the raw gas A and the oxidizing gas A are used more efficiently,
Efficiency is improved.

In the present invention, not only the heating by the cooling water flowing in the passage provided inside the separator of the fuel cell stack and the heating by the fuel gas and the oxidizing gas are used, but also the fuel cell stack 3 (the fuel cell Cell 30)
An electric current is passed through and heating is performed using the heat generated by the internal resistance loss. That is, since the fuel cell stack 3 (the fuel cell unit 30 of the fuel cell stack) itself heats by heating, the heating efficiency is very high. Therefore, the temperature can be raised in a very short time.

When heating is performed by power generation, water generated by power generation is used to humidify the electrolyte membrane 31. That is, the fuel cell stack 3 (of the fuel cell 3
0) water will be supplied on top, and the efficiency of humidification will be very high. Therefore, humidification can be performed in a very short time.

According to the present invention, when the fuel cell system is started up, the fuel cell stack generates electric power with a small output to generate heat and generate water in the fuel cell, so that the fuel cell can be directly warmed and humidified. . Then, it becomes possible to significantly reduce the startup time of the entire fuel cell system.

(Embodiment 2) Next, the configuration of the second embodiment of the fuel cell system of the present invention will be described. FIG. 4 is a diagram showing the configuration of the fuel cell system according to the second embodiment of the present invention. The fuel cell system includes a fuel gas supply unit 1, an oxidizing gas supply unit 2, a fuel cell stack 3, a heating unit 5, a cooling unit 6, a pump 7, a voltage sensor 8, a current sensor 9, a DC / DC converter 19 and 2.
Secondary battery 20, second fuel gas flow control valve 14, second oxidizing gas flow control valve 15, first fuel gas flow control valve 16, first
An oxidizing gas flow rate control valve 17 and a control unit 18 are provided. Then, it is connected to the load device 4 and supplies power to the load device 4. Then, the first fuel gas pipes 52-1 to 52-3 and the second fuel gas pipe 54-1 which are pipes for fuel gas
54-2, first oxidizing gas pipes 53-1 to 53-3 and second oxidizing gas pipes 55-1 to 5-5 which are pipes for oxidizing gas
5-2, cooling water pipes 57-1 to 5-5 which are pipes for cooling water
7-4. In addition, wiring 58- which is wiring for electricity
1 to 58-2, wirings 59-3 to 59-for the secondary battery 20
4, wiring 60-1 and 60-2 for the load device 4 are provided.

In this embodiment, a DC / DC converter 19 is used instead of the discharge controller 12 and the discharge resistor 13 (diode 10, output switch 11) used for power generation in the first embodiment.
Also, the second embodiment is different from the first embodiment in that the secondary battery 20 is used.

DC / D as one of the configurations of the power adjusting unit
The C converter 19 is controlled by the control unit 18, and the wiring 58
-1 and the wiring 58-2 supply electric power generated by the fuel cell stack 3. The stack current Is of the fuel cell stack 3 is controlled to have a predetermined value. In that case, the stack voltage Vs has a value shown in the relationship of FIG. 6 based on the temperature and the stack current Is. And DC / D
The C converter 19 uses the electric power Ws of the fuel cell stack 3.
(Stack voltage Vs and stack current Is) is a system voltage V determined based on the secondary battery 20 and the load device 4.
Converting the power _{W X (= ρ × Vs ×} Is) having _X.
Then, the data is output to the wiring 60-1 and the wiring 60-2. However, ρ is the power conversion efficiency of the DC / DC converter 19. The current I _{X at} that time is Ix = ρ × Vs × Is /
V _X.

2 as one load of the configuration of the power adjusting unit
The secondary battery 20 stores the electric power generated by the fuel cell stack 3 when the fuel cell stack 3 is activated. The load device 4 is connected in parallel to the DC / DC converter 19 via a wire 59-1 and a wire 59-2. 2
The function of the secondary battery 20 can be replaced by a capacitor or the like depending on the required amount of electricity.

The other structure is similar to that of the first embodiment, and the description thereof is omitted.

Next, the operation of the second embodiment of the fuel cell system of the present invention (method of starting the fuel cell system) will be described with reference to FIGS. 4, 6 and 7.

In the present embodiment, the stack current Is of the fuel cell stack 3 is controlled by the DC instead of the discharge controller 12.
This is different from the first embodiment in that the / DC converter 19 is used and generated power is stored in the secondary battery 20.
However, in consideration of the above points, the other points are the same as those in the first embodiment.
Since the operation can be performed in the same manner as, the description thereof will be omitted.

Also in this embodiment, the same effect as that of the first embodiment can be obtained. Further, in this embodiment, since the electric power generated by the fuel cell stack 3 is stored when the fuel cell stack 3 is started up, for example, the fuel cell stack starting electric power (eg, the power of the pump 7 and the power of opening / closing the valve) is supplied. It can be used for supplying electric power to the load device 4 when the electric power of the fuel cell stack is insufficient due to load fluctuation. That is, since the power can be used effectively,
Energy efficiency is improved.

(Embodiment 3) Next, the configuration of the third embodiment of the fuel cell system of the present invention will be described. FIG. 5 is a diagram showing the configuration of the fuel cell system according to the third embodiment of the present invention. The fuel cell system includes a fuel gas supply unit 1, an oxidizing gas supply unit 2, a fuel cell stack 3, a heating unit 5, a cooling unit 6, a pump 7, a voltage sensor 8, a current sensor 9, a diode 10, an output switch 11, and discharge control. Section 12, electric heating section 13 ', second fuel gas flow rate control valve 14, second oxidizing gas flow rate control valve 15, first
Fuel gas flow control valve 16, first oxidizing gas flow control valve 1
7, a control unit 18 is provided. Then, it is connected to the load device 4 and supplies power to the load device 4. Then, the first fuel gas pipes 52-1 to 52- which are pipes for fuel gas
3 and 2nd fuel gas piping 54-1 to 54-2, 1st oxidizing gas piping 53-1 to 53-3 which are piping for oxidizing gas, and 2nd oxidizing gas piping 55-1 to 55-2, cooling water It has the cooling water piping 57-1 to 57-4 which is piping for. Further, wirings 58-1 to 58-2 which are wirings for electricity, wirings 59-1 to 59-2 for the discharge control section 12, and the electric heating section 1
Wirings 61-1 'and 61-2' for 3'are provided.

In this embodiment, instead of the discharge resistor 13 used for power generation in the first embodiment, an electric heating section 13 'is provided in the cooling water pipe 57-1 so that the electric power generated when the fuel cell stack 3 is started up is supplied. It is different from the first embodiment in that it is used as an electric heating unit 13 'for heating the cooling water.

The electric heating unit 13 ′ as one load of the configuration of the electric power adjusting unit is an electric heater, and is provided in the middle of the cooling water pipe 57-1 between the pump 7 and the heating unit 5. Then, under the control of the discharge control unit 12, the cooling water is heated using the electric power generated when the fuel cell stack 3 is started.

The other structure is similar to that of the first embodiment, and the description thereof is omitted.

Next, the operation of the third embodiment of the fuel cell system according to the present invention (method of starting the fuel cell system) will be described with reference to FIGS. 5, 6 and 7.

In the present embodiment, the electric power generated at the time of starting the fuel cell stack 3 is not discharged by the discharge resistor 13, but the electric power is used to heat the cooling water by the electric heating unit 13 '. Different from Example 1. However, in consideration of the above points, the other points can be performed by the same operation as that of the first embodiment, and thus the description thereof will be omitted.

Also in this embodiment, the same effect as that of the first embodiment can be obtained. Further, in the present embodiment, the cooling water is heated by the heating unit 5, and is also heated by the electric heating unit 13 ', so that the temperature of the cooling water becomes high. And Example 1
Compared with the second embodiment, the temperature of the fuel cell stack 3 can reach the operating temperature T _{0 in} a shorter time. That is, the time between t ₂ and t ₃ can be shortened.
Moreover, since the electric power can be effectively used, the energy efficiency is improved.

Although the methods of using the electric power generated when the fuel cell system is started are described in Examples 1 to 3, the present invention is not limited to these methods.

The present invention can be similarly used not only at the time of starting the fuel cell system, but also when a state where the temperature of the fuel cell stack is desired to be raised occurs during the operation.
In that case, the temperature can be raised more quickly by increasing the amount of electric power generated by the fuel cell stack, as compared with the case where the cooling in the cooling unit 6 is stopped and the temperature is raised.

[0098]

As described above, according to the present invention, it is possible to efficiently warm and humidify the fuel cell stack when the fuel cell system is started, and it is possible to shorten the startup time of the fuel cell system.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a fuel cell system according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a fuel cell and a separator.

FIG. 3 is a perspective view showing a configuration of a fuel cell stack.

FIG. 4 is a diagram showing a configuration of a fuel cell system according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a fuel cell system according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between a stack voltage Vs and a stack current Is of a fuel cell stack.

FIG. 7 is a timing chart showing an operation at startup of the fuel cell system.

FIG. 8 is a diagram showing a configuration of a conventional fuel cell system.

[Explanation of symbols]

1 Fuel gas supply section 2 Oxidizing gas supply unit 3 Fuel cell stack 4 load device 5 heating section 6 Cooling unit 7 pumps 8 voltage sensor 9 Current sensor 10 diode 11 Output switch 12 Discharge controller 13 Discharge resistance 13 'Electric heating unit 14 Second fuel gas flow control valve 15 Second oxidizing gas flow control valve 16 First fuel gas flow control valve 17 First oxidizing gas flow control valve 18 Control unit 19 DC / DC converter 20 secondary battery 30 (-1 to n-1) fuel cell 31 Electrolyte membrane 32 fuel pole 33 oxygen pole 34 (-1 to n) separator 35 Fuel gas passage 36 Oxidizing gas passage 39 Power Generation Department 40 current collector plate 41 Insulation plate 42 End plate 43 Fuel gas inlet 44 Cooling water inlet 45 Oxidizing gas inlet 46 Current collector plate 47 insulating plate 48 End plate 49 Oxidizing gas outlet 50 Cooling water outlet 51 Fuel gas outlet 52-1 to 52-3 First fuel gas pipe 53-1 to 53-3 First oxidizing gas pipe 54-1 to 54-2 Second fuel gas pipe 55-1 to 55-2 Second oxidizing gas pipe 57-1 (') to 57-4 Cooling water piping 58-1 to 58-2 wiring 59-1 to 59-2 Wiring 60-1 to 61-2 Wiring 61-1 (') to 61-2 (') wiring 101 Fuel gas supply unit 102 oxidizing gas supply unit 103 fuel cell stack 104 load device 105 heating part 106 Cooling unit 107 pumps 110 diode 111 output switch 116 Fuel gas flow control valve 117 Oxidizing gas flow control valve 118 control unit 152-1 to 152-3 Fuel gas piping 153-1 to 153-3 Oxidizing gas piping 157-1 to 157-4 Cooling water piping 158-1 to 158-2 wiring

Claims (14)

[Claims] 1. A control unit, a fuel cell stack supplied with an oxidant gas and a fuel gas, and a current adjusting unit electrically connected to the fuel cell stack, wherein the control unit comprises: When raising the temperature of the fuel cell stack,
A fuel cell system that controls the current adjusting unit so that a stack current as a current is passed through the fuel cell stack. 2. The fuel cell system according to claim 1, wherein the stack current is a substantially constant current. 3. A current sensor for measuring the stack current, and a voltage sensor for measuring a stack voltage as a voltage of the fuel cell stack, further comprising: the controller controlling the temperature of the fuel cell stack and the temperature of the fuel cell stack. The current adjusting unit is controlled so that a stack voltage and a stack current are associated with each other, and the ratio of the measured stack voltage to the open circuit voltage of the fuel cell stack becomes the stack current having a preset value. The fuel cell system according to claim 1. 4. The current adjusting unit includes a load, and the current adjusting unit controls the size of the load to adjust the stack current. Fuel cell system. 5. The fuel cell stack further comprises a first heating section for heating water flowing in the fuel cell stack, wherein the control section heats the fuel cell stack by the heating before flowing the stack current at the time of temperature rise. The fuel cell system according to any one of claims 1 to 4, wherein the first heating unit is controlled to raise the temperature of the fuel cell. 6. The fuel cell system according to claim 5, wherein the load is a second heating unit that heats the water based on the stack current. 7. The current adjusting unit includes a power converter that converts the characteristics of the electric power of the fuel cell stack, and a secondary battery that is charged by the converted electric power, and the control unit is the The fuel cell system according to claim 1, wherein a stack current is controlled by the power converter. 8. A step of supplying a fuel gas and an oxidizing gas to the fuel cell stack, and a step of supplying a stack current as a current to the fuel cell stack when the temperature of the fuel cell stack is raised. How to start the fuel cell system. 9. The step of causing the stack current to flow comprises bringing the fuel cell stack to a preset first temperature,
Or, a step of raising the temperature for a preset first time, and from the preset second temperature after the start of the raising of temperature, or
The method of starting the fuel cell system according to claim 8, further comprising: flowing the stack current after a preset second time. 10. The step of passing the stack current comprises: The stack current is a preset constant current, The method for starting the fuel cell system according to claim 8. 11. The step of causing the stack current to flow includes a step of specifying a temperature of the fuel cell stack based on the stack current and a stack voltage as a voltage of the fuel cell stack; 10. The fuel cell system according to claim 8, further comprising a step of changing the stack current so that a voltage has a preset ratio with respect to an open circuit voltage of the fuel cell stack at the temperature. starting method. 12. A step of supplying a fuel gas and an oxidizing gas to a fuel cell stack, the fuel cell stack up to a preset first temperature,
Or, a step of raising the temperature for a preset first time, and from the preset second temperature after the start of the raising of temperature, or
A program for causing a computer to execute a method comprising: passing the stack current after a preset second time. 13. The program for causing a computer to execute the method according to claim 12, wherein in the step of causing the stack current to flow, the stack current is a preset constant current. 14. The step of causing the stack current to flow includes a step of specifying a temperature of the fuel cell stack based on the stack current and a stack voltage as a voltage of the fuel cell stack; 13. The method according to claim 12, further comprising the step of changing the stack current so that a voltage is a preset ratio with respect to an open circuit voltage of the fuel cell stack at the temperature. Program for.