JP2023102957A - Fuel battery system - Google Patents

Abstract

To provide a fuel battery system capable of appropriately performing humidity regulation of a fuel battery.SOLUTION: A fuel battery system comprises a fuel battery 10, a fuel gas supply passage 40, an oxidation gas supply passage 60, humidification devices 47, 67, an ECU, and a resistance meter 81. The humidification devices 47, 67 are provided in the fuel gas supply passage 40 and the oxidation gas supply passage 60 and perform humidification on fuel gas and oxidation gas. The ECU is configured to be capable of controlling the humidification devices 47, 67. The resistance meter 81 detects an electric resistance value Z of the fuel battery 10. The fuel battery system comprises: an ampere meter 82 for detecting current density J of the fuel battery: pressure sensors 83, 84 for detecting a pressure loss ΔP of oxidation gas in the fuel battery; and a water level sensor 85 for detecting an amount V of produced water produced in the fuel battery. The ECU is configured to control the humidification devices 47, 67 on the basis of all of the electric resistance value Z, the current density J, the pressure loss ΔP, and the amount V of produced water.SELECTED DRAWING: Figure 1

Description

The present invention relates to fuel cell systems.

Patent Literature 1 discloses a fuel cell system.
A polymer electrolyte fuel cell (hereinafter referred to as a fuel cell) includes a stack composed of a plurality of stacked cells each having a membrane electrode assembly and an anode-side separator and a cathode-side separator sandwiching the membrane electrode assembly. A fuel gas channel through which fuel gas flows is formed in the anode-side separator. The cathode-side separator is formed with an oxidizing gas channel through which the oxidizing gas flows. The stack is provided with a fuel gas manifold that supplies fuel gas to the fuel gas channel and an oxidant gas manifold that supplies oxidant gas to the oxidant gas channel. A fuel gas supply passage is connected to the fuel gas manifold. An oxidizing gas supply passage is connected to the oxidizing gas manifold. The oxidizing gas supply passage is provided with a main passage provided with a humidifier and a bypass passage bypassing the humidifier and provided with a bypass valve. The opening/closing operation of the bypass valve is controlled by the ECU. Further, the fuel cell is provided with an impedance meter for detecting the impedance of the fuel cell.

In the fuel cell system disclosed in Patent Document 1, the ECU controls the opening/closing operation of the bypass valve based on the impedance of the fuel cell, thereby adjusting the humidity of the oxidant gas. Specifically, when the impedance is equal to or lower than the lower limit value, the ECU judges that there is a large amount of accumulated water in the fuel cell, and opens the bypass valve to execute accumulated water reduction control to reduce the accumulated water in the fuel cell. Further, when the impedance is equal to or higher than the upper limit, the ECU determines that the amount of accumulated water in the fuel cell is small, that is, the fuel cell is dry, and closes the bypass valve to cancel the accumulated water reduction control.

JP 2013-239290 A

By the way, even if the impedance of the fuel cell, that is, the electrical resistance value is the same, the amount of water retained in the fuel cell may differ. Therefore, there is room for improvement in properly adjusting the humidity of the fuel cell.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel cell system capable of appropriately adjusting the humidity of the reaction gas according to the humidity of the cell.

A fuel cell system for solving the above problems comprises: a fuel cell comprising: an anode separator having a fuel gas channel through which fuel gas flows; a cathode separator having an oxidizing gas channel through which oxidant gas flows; and a membrane electrode assembly sandwiched between the anode separator and the cathode separator; a fuel gas supply passage connected to the fuel gas channel and supplying fuel gas to the fuel gas channel; a controller configured to be able to control the humidifier; and an electrical resistance value detector that detects an electrical resistance value of the fuel cell, the fuel cell system comprising at least one of a current density detector that detects the current density of the fuel cell, a pressure loss detector that detects pressure loss of oxidizing gas in the fuel cell, and a generated water amount detector that detects the amount of water generated in the fuel cell, wherein the controller controls the electrical resistance, the current density, the It is configured to control the humidifier based on at least one of pressure loss and the amount of water produced.

Even if the electrical resistance value is the same, there is a high possibility that more water will remain in the oxidizing gas flow path (hereinafter simply referred to as the fuel cell) of the cathode side separator when the current density is high than when the current density is low. Also, even if the electrical resistance value is the same, when the pressure loss of the oxidizing gas is high, there is a high possibility that there is more water remaining in the fuel cell than when the pressure loss is low. Also, even if the electric resistance value is the same, there is a high possibility that there is more water remaining in the fuel cell when the amount of generated water is large than when the amount of water is small.

According to the above configuration, the humidifier is controlled based on at least one of the current density, the pressure loss of the oxidizing gas, and the amount of water produced, in addition to the electrical resistance value. Therefore, the humidifying device can be controlled in accordance with the actual state of water remaining in the fuel cell. Therefore, it is possible to appropriately adjust the humidity of the fuel cell.

FIG. 1 is a schematic diagram showing a schematic configuration of a fuel cell system according to the first embodiment. FIG. 2 is a block diagram showing the electrical configuration of the fuel cell system according to the first embodiment. FIG. 3 is a flow chart showing the procedure for controlling the humidifier of the fuel cell system according to the first embodiment. FIG. 4 is a schematic diagram showing a schematic configuration of a fuel cell system according to the second embodiment. FIG. 5 is a block diagram showing the electrical configuration of the fuel cell system according to the second embodiment. FIG. 6 is a flow chart showing the procedure for controlling the humidifier of the fuel cell system according to the second embodiment.

<First Embodiment>
A first embodiment of a fuel cell system will be described below with reference to FIGS. 1 to 3. FIG.
As shown in FIG. 1, the fuel cell system includes a fuel cell 10, a fuel gas supply passage 40, an oxidizing gas supply passage 60, and a controller 90.

First, the fuel cell 10 will be explained.
<Fuel cell 10>
As shown in FIG. 1, the fuel cell 10 includes a cell stack 11 and a pair of end plates 16,17.

The cell stack 11 is configured by stacking a plurality of sheet-like unit cells 12 in the thickness direction.
Note that, hereinafter, the stacking direction of the unit cells 12 may be simply referred to as the stacking direction.

The single cell 12 includes an anode-side separator 13 , a cathode-side separator 14 , and a membrane electrode assembly 15 sandwiched between the anode-side separator 13 and the cathode-side separator 14 .

The anode-side separator 13, the cathode-side separator 14, and the membrane electrode assembly 15 are all sheet-like and laminated in the thickness direction.
The anode-side separator 13 has a fuel gas channel 13a through which fuel gas flows.

The cathode-side separator 14 has an oxidizing gas flow path 14a through which oxidizing gas flows.
A pair of end plates 16 and 17 are provided so as to sandwich the cell stack 11 from both sides in the stacking direction.

The cell stack 11 is provided with a fuel gas supply manifold 21 and a fuel gas discharge manifold 22 . The fuel gas supply manifold 21 and the fuel gas discharge manifold 22 communicate with the inflow and outflow portions of the fuel gas channel 13a of each anode-side separator 13, respectively.

The cell stack 11 is provided with an oxidizing gas supply manifold 31 and an oxidizing gas discharge manifold 32 . The oxidant gas supply manifold 31 and the oxidant gas discharge manifold 32 communicate with the inflow and outflow portions of the oxidant gas channels 14a of the cathode-side separators 14, respectively.

<Fuel Gas Supply Passage 40 and Fuel Gas Discharge Passage 50>
(Fuel gas supply passage 40)
As shown in FIG. 1, a fuel gas supply passage 40 is connected through a fuel gas supply manifold 21 to the fuel gas flow path 13a.

The fuel gas supply passage 40 has a main passage 41 and a bypass passage 42 .
The main passage 41 is provided with a fuel gas supply portion 43, a humidification valve 44, and a humidifier 45 in this order from the upstream side.

The fuel gas supply unit 43 includes a tank storing hydrogen as a high-pressure fuel gas, a decompression device for reducing the pressure of the high-pressure fuel gas, an injection device for injecting the fuel gas, and the like.
The humidifier 45 humidifies the fuel gas by adding water vapor. The water vapor may be supplied from the outside of the fuel cell 10, or may be supplied from a fuel gas discharge passage 50, which will be described later.

The bypass passage 42 is connected to the main passage 41 so as to bypass the humidification valve 44 and the humidifier 45 . A bypass valve 46 is provided in the bypass passage 42 .

A humidifying device 47 is configured by the humidifying valve 44 , the humidifier 45 , and the bypass valve 46 .
(Fuel gas discharge passage 50)
A fuel gas discharge passage 50 is connected via a fuel gas discharge manifold 22 to the fuel gas flow path 13a.

The fuel gas discharge passage 50 is connected between the humidification valve 44 and the humidifier 45 in the main passage 41 of the fuel gas supply passage 40 .
The fuel gas discharge passage 50 is provided with a gas-liquid separator 51 and a circulation pump 52 in this order from the upstream side.

A purge passage 53 communicating with the atmosphere is connected between the gas-liquid separator 51 and the circulation pump 52 in the fuel gas discharge passage 50 . A purge valve 54 is provided in the purge passage 53 .

<Oxidant Gas Supply Passage 60 and Oxidant Gas Discharge Passage 70>
(Oxidizing gas supply passage 60)
As shown in FIG. 1, an oxidizing gas supply passage 60 is connected to the oxidizing gas flow path 14a via an oxidizing gas supply manifold 31. As shown in FIG.

The oxidizing gas supply passage 60 has a main passage 61 and a bypass passage 62 .
The main passage 61 is provided with an oxidizing gas supply unit 63, a humidification valve 64, and a humidifier 65 in this order from the upstream side.

The oxidizing gas supply unit 63 includes an air cleaner that filters the oxidizing gas, which is outside air containing oxygen, a compressor that pumps the oxidizing gas, and the like.
The humidifier 65 humidifies the oxidizing gas by adding water vapor. The water vapor may be supplied from the outside of the fuel cell 10, or may be supplied from an oxidizing gas discharge passage 70, which will be described later.

The bypass passage 62 is connected to the main passage 61 so as to bypass the humidification valve 64 and the humidifier 65 . A bypass valve 66 is provided in the bypass passage 62 .

The humidifying valve 64, the humidifier 65, and the bypass valve 66 constitute a humidifying device 67 according to the present invention.
(Oxidizing gas discharge passage 70)
An oxidant gas discharge passage 70 is connected to the oxidant gas flow path 14 a via the oxidant gas discharge manifold 32 .

The oxidant gas discharge passage 70 is connected between the humidification valve 64 and the humidifier 65 in the main passage 61 of the oxidant gas supply passage 60 .
A gas-liquid separator 71 and a circulation pump 72 are provided in order from the upstream side of the oxidizing gas discharge passage 70 .

A purge passage 73 communicating with the atmosphere is connected between the gas-liquid separator 71 and the circulation pump 72 in the oxidizing gas discharge passage 70 . A purge valve 74 is provided in the purge passage 73 .

In the fuel cell 10 , the fuel gas supplied through the fuel gas supply passage 40 flows through the fuel gas channel 13 a of each single cell 12 . At this time, part of the fuel gas flows into the membrane electrode assembly 15 .

Further, the oxidizing gas supplied through the oxidizing gas supply passage 60 flows through the oxidizing gas flow path 14a. At this time, part of the oxidizing gas flows into the membrane electrode assembly 15 .
The electrochemical reaction between the fuel gas and the oxidizing gas in the membrane electrode assembly 15 generates electricity and produces water.

Part of the fuel gas is returned to the fuel gas supply passage 40 from the fuel gas passage 13 a through the fuel gas discharge passage 50 . At this time, part of the water vapor contained in the fuel gas is separated from the fuel gas when passing through the gas-liquid separator 71 .

Part of the oxidant gas is returned to the oxidant gas supply passage 60 from the oxidant gas passage 14 a through the oxidant gas discharge passage 70 . At this time, part of the water vapor contained in the oxidizing gas is separated from the oxidizing gas when passing through the gas-liquid separator 71 .

<Resistance meter 81>
As shown in FIG. 1, the fuel cell system includes a ohmmeter 81 that detects the electrical resistance value Z (impedance) of the fuel cell 10 .

The ohmmeter 81 corresponds to the electric resistance value detection section according to the present invention.
<Ammeter 82>
As shown in FIG. 1, the fuel cell system has an ammeter 82 that detects the current density J of the fuel cell 10 .

The ammeter 82 is provided in series with the external load 81A in the circuit through which the current generated by the fuel cell 10 flows.
The ammeter 82 corresponds to the current density detector according to the invention.

<Pressure sensors 83, 84>
As shown in FIG. 1, the main passage 61 of the oxidant gas supply passage 60 is provided with a supply side pressure sensor 83 for detecting the pressure Pin of the oxidant gas supplied to the fuel cell 10 . The supply-side pressure sensor 83 is provided downstream of the humidifier 65 in the main passage 61 .

The oxidant gas discharge passage 70 is provided with a discharge side pressure sensor 84 that detects the pressure Pout of the oxidant gas supplied from the fuel cell 10 . The discharge-side pressure sensor 84 is provided upstream of the gas-liquid separator 71 in the oxidant gas discharge passage 70 .

The difference (=Pin−Pout) between the oxidizing gas pressure Pin detected by the supply side pressure sensor 83 and the oxidizing gas pressure Pout detected by the discharge side pressure sensor 84 is the pressure loss ΔP of the oxidizing gas in the fuel cell 10 . Therefore, the supply-side pressure sensor 83 and the discharge-side pressure sensor 84 constitute a pressure loss detection section according to the present invention.

<Water level sensor 85>
The gas-liquid separator 71 provided in the oxidizing gas discharge passage 70 has a storage section (not shown) that stores the separated water. The gas-liquid separator 71 is provided with a water level sensor 85 for detecting the water level of the reservoir. The water level in the reservoir increases as the amount of water generated V, which is the amount of water generated in the fuel cell 10, increases. Therefore, the generated water volume V can be grasped from the water level of the reservoir. In this embodiment, the water level sensor 85 constitutes a generated water amount detection unit.

<Control unit 90>
As shown in FIG. 2, the injection device of the fuel gas supply section 43 and the compressor of the oxidant gas supply section 63 are electrically connected to the control section 90 . Humidifiers 45 , 65 , humidification valves 44 , 64 , and bypass valves 46 , 66 are electrically connected to the controller 90 . Circulation pumps 52 , 72 and purge valves 54 , 74 are electrically connected to the controller 90 . Various detection units such as a resistance meter 81 , an ammeter 82 , pressure sensors 83 and 84 and a water level sensor 85 are electrically connected to the control unit 90 .

The control unit 90 is configured to control the supply amount of the fuel gas by controlling the drive of the injection device of the fuel gas supply unit 43 .
The control unit 90 is configured to control the supply amount of the oxidizing gas by controlling the driving of the compressor of the oxidizing gas supply unit 63 .

The controller 90 is configured to control the mode of humidification of the fuel gas by controlling the opening/closing of the humidification valve 44 , the drive control of the humidifier 45 , and the opening/closing control of the bypass valve 46 .

The control unit 90 is configured to control the humidification mode of the oxidizing gas by controlling the opening/closing of the humidification valve 64 , the drive control of the humidifier 65 , and the opening/closing control of the bypass valve 66 .

The controller 90 is also configured to control the opening and closing of the purge valves 54 and 74 .
By the way, it is necessary to suppress humidification of the fuel gas and the oxidant gas by the humidifiers 47 and 67 as the amount of generated water (hereinafter referred to as stagnant water) remaining in the fuel gas flow path 13a and the oxidant gas flow path 14a increases.

Here, the electric resistance value Z of the fuel cell 10 becomes smaller when there is more water remaining in the oxidizing gas flow path 14a of the cathode-side separator 14 than when there is less water.
Therefore, when the electric resistance value Z of the fuel cell 10 is small, it is necessary to suppress the humidification of the fuel gas and the oxidant gas by the humidifiers 47 and 67 compared to when the electric resistance value Z is large.

However, even if the electrical resistance value Z is the same, when the current density J is high, there is a high possibility that more water will remain in the oxidizing gas flow path 14a of the cathode-side separator 14 than when the current density J is low.
Also, even if the electrical resistance value Z is the same, there is a high possibility that there is more water remaining in the fuel cell 10 when the pressure loss ΔP of the oxidizing gas is high than when the pressure loss ΔP is low.

Further, even if the electrical resistance value Z is the same, there is a high possibility that the water remaining in the fuel cell 10 is larger when the generated water amount V is large than when it is small.
Therefore, in the present embodiment, the controller 90 controls the humidifiers 47 and 67 based on all of the electrical resistance value Z of the fuel cell 10, the current density J of the fuel cell 10, the pressure loss ΔP of the oxidant gas in the fuel cell 10, and the amount V of water generated in the fuel cell 10.

Specifically, the control unit 90 has a memory 91 that stores a map that defines the relationship between the electrical resistance value Z, current density J, pressure loss ΔP, amount of water generated V, and target control states of the humidifiers 47 and 67 .

In this map, the relationship between the electrical resistance value Z, the current density J, the pressure loss ΔP of the oxidizing gas, the generated water amount V, and whether or not the stagnant water in the oxidizing gas flow path 14a is in a flooded state is defined as a matrix.

The relationship between the electrical resistance value Z, the current density J, the pressure loss ΔP of the oxidizing gas, the generated water amount V, and whether or not the flooding state is present is set in advance through experiments or the like.
Specifically, in this map, when the electrical resistance value Z is small, compared to when it is large, if the other three parameters (current density J, pressure loss ΔP of the oxidizing gas, amount of water generated V) are constant, the possibility of the flooding state is set higher.

Also, when the current density J is high, compared to when the current density J is low, if the other three parameters (electrical resistance value Z, pressure loss ΔP of oxidizing gas, amount of generated water V) are constant, the possibility of flooding is set to be high.

Also, when the pressure loss ΔP of the oxidizing gas is high, compared to when the pressure loss ΔP is low, if the other three parameters (electrical resistance value Z, current density J, and amount of water generated V) are constant, the possibility of a flooding state is set higher.

Also, when the generated water volume V is large, compared to when it is small, if the other three parameters (electrical resistance value Z, current density J, pressure loss ΔP of oxidizing gas) are constant, the possibility of flooding is set to be high.

In the flooding state, the target control state is set so that the humidification by the humidifiers 47, 67 is stopped.

The control unit 90 is configured to determine the target control state of the humidifiers 47 and 67 by referring to the map, and control the humidifiers 47 and 67 so as to achieve the target control state.
The control unit 90 derives the oxidant gas pressure loss ΔP in the fuel cell 10 from the difference between the oxidant gas pressure Pin detected by the supply side pressure sensor 83 and the oxidant gas pressure Pout detected by the discharge side pressure sensor 84.

Next, a processing procedure for controlling the humidifiers 47 and 67 by the controller 90 will be described with reference to the flowchart of FIG. This series of processes is repeatedly executed by the control unit 90 at predetermined time intervals while the fuel cell 10 is in operation.

As shown in FIG. 3 , in this series of processes, the control unit 90 first reads the electrical resistance value Z and the current density J from the resistance meter 81 and the ammeter 82 . The control unit 90 also reads the oxidizing gas pressures Pin and Pout, the oxidizing gas pressure loss ΔP, and the generated water amount V from the pressure sensors 83 and 84 and the water level sensor 85 (step S1).

Next, the control unit 90 determines the target control state of the humidifiers 47 and 67 with reference to the map.
Here, when it is determined that the flooding state is present (step S2: “YES”), the controller 90 stops humidification by the humidifiers 47 and 67 . That is, the controller 90 closes the humidification valves 44, 64, opens the bypass valves 46, 66, and stops driving the humidifiers 45, 65 (step S3).

Then, the control unit 90 terminates this series of processes.
On the other hand, when determining that the flooding state is not in effect (step S2: “NO”), the control unit 90 executes humidification by the humidifiers 47 and 67 . That is, the controller 90 opens the humidification valves 44, 64, closes the bypass valves 46, 66, and drives the humidifiers 45, 65 (step S4).

Then, the control unit 90 terminates this series of processes.
Next, the operation of this embodiment will be described.
As shown in FIG. 3, in addition to the electric resistance value Z, the humidifiers 47 and 67 are controlled based on all of the current density J, the pressure loss ΔP of the oxidizing gas, and the amount V of water produced. Therefore, the humidifiers 47 and 67 can be controlled in accordance with the actual state of the accumulated water in the fuel cell 10 .

Next, the effects of this embodiment will be described.
(1-1) The controller 90 is configured to control the humidifiers 47 and 67 based on all of the electrical resistance value Z, the current density J, the pressure loss ΔP of the oxidizing gas, and the generated water volume V.

With such a configuration, the humidity of the fuel cell 10 can be adjusted more appropriately because of the effects described above.
(1-2) The control unit 90 is configured to determine the target control state of the humidifiers 47 and 67 by referring to the map, and to control the humidifiers 47 and 67 so as to achieve the target control state.

According to such a configuration, the target control state of humidifiers 47 and 67 is determined by referring to a map stored in advance in memory 91 of control unit 90 . Then, the humidifiers 47 and 67 are controlled so as to reach the target control state. Therefore, the humidifiers 47 and 67 can be easily controlled.

(1-3) Humidifier 47 includes humidifier 45 and bypass valve 46 . A humidifier 67 includes a humidifier 65 and a bypass valve 66 . The controller 90 is configured to control the driving of the humidifiers 45 and 65 and the opening/closing control of the bypass valves 46 and 66 .

According to this configuration, in addition to the electric resistance value Z, the drive control of the humidifiers 45 and 65 and the opening/closing control of the bypass valves 46 and 66 are controlled based on all of the current density J, the pressure loss ΔP of the oxidizing gas, and the generated water volume V. Therefore, the driving control of the humidifiers 45 and 65 and the opening/closing control of the bypass valves 46 and 66 are controlled in accordance with the actual state of the stagnant water in the fuel cell 10 . Therefore, the humidity of the fuel cell 10 can be properly adjusted.

<Second embodiment>
A second embodiment of the fuel cell system will be described below with reference to FIGS. 4 to 6. FIG.
This embodiment differs from the first embodiment in the configuration of a humidifier 147 that humidifies the fuel gas and the humidifier 167 that humidifies the oxidant gas, and in the control mode of the humidifiers 147 and 167 .

The following description will focus on differences from the first embodiment. In addition, hereinafter, redundant description will be omitted by assigning the same reference numerals to the same configurations as in the first embodiment.
<Humidifier 147, 167>
As shown in FIG. 4, instead of the humidifier 45, a humidifier 147 is provided. In addition, in this embodiment, the bypass passage 42, the humidification valve 44, and the bypass valve 46 are not provided.

The humidifier 147 has a humidity sensor 86 that detects the humidity of the fuel gas passing through the humidifier 147 .
A humidifier 167 is provided instead of the humidifier 65 . In addition, in this embodiment, the bypass passage 62, the humidification valve 64, and the bypass valve 66 are not provided.

The humidifier 167 has a humidity sensor 87 that detects the humidity of the oxidizing gas passing through the humidifier 167 . The humidity sensor 87 corresponds to the humidity detector according to the invention.
<Control unit 90>
As shown in FIG. 5, humidifiers 147 and 167 are electrically connected to the controller 90 . A resistance meter 81 , an ammeter 82 , and humidity sensors 86 and 87 are electrically connected to the controller 90 .

The controller 90 is configured to control the humidification mode of the fuel gas by controlling the driving of the humidifier 147 .
The controller 90 is configured to control the humidification mode of the oxidant gas by controlling the driving of the humidifier 167 .

The control unit 90 is configured to set a target value Htrg1 for the humidity of the fuel gas passing through the humidifier 147 based on the electrical resistance value Z and the current density J, and control the humidifier 147 so that the humidity of the fuel gas detected by the humidity sensor 86 reaches the target value Htrg1.

Specifically, the control unit 90 has a memory 91 that defines the relationship between the electrical resistance value Z and the target value Htrg1 and stores a plurality of maps set for each magnitude of the current density J. FIG. The control unit 90 is configured to refer to the map to determine the target value Htrg1 and control the humidifying device 147 so as to achieve the target value Htrg1.

In this map, even if the electrical resistance value Z is the same, the higher the current density J, the more water remains in the oxidizing gas flow path 14a, and the fuel gas target value Htrg1 is set to be smaller.

The control unit 90 is configured to set a target value Htrg2 of the humidity of the oxidizing gas passing through the humidifying device 167 based on the electrical resistance value Z and the current density J, and control the humidifying device 167 so that the humidity of the oxidizing gas detected by the humidity sensor 87 reaches the target value Htrg2.

Specifically, the control unit 90 has a memory 91 that defines the relationship between the electrical resistance value Z and the target value Htrg2 and stores a plurality of maps set for each magnitude of the current density J. FIG. The control unit 90 is configured to refer to the map to determine the target value Htrg2, and control the humidifying device 167 so as to achieve the target value Htrg2.

In this map, even if the electric resistance value Z is the same, the larger the current density J, the more water remains in the oxidizing gas flow path 14a, and the oxidizing gas target value Htrg2 is set to be smaller.

Next, a processing procedure for controlling the humidifiers 147 and 167 by the controller 90 will be described with reference to the flowchart of FIG. This series of processes is repeatedly executed by the control unit 90 at predetermined time intervals while the fuel cell 10 is in operation.

As shown in FIG. 6, in this series of processes, the controller 90 first reads the current density J from the ammeter 82 (step S11).
Next, the control unit 90 determines whether or not the current density J has changed by a predetermined value or more from the current density J read in the previous control cycle (step S12).

If it is determined that the current density J has not changed by a predetermined value or more (step S12: "YES"), there is a high possibility that the amount of stagnant water in the oxidizing gas flow path 14a has hardly changed since the previous control cycle. Therefore, the control unit 90 sets the values set in the previous control cycle as the target value Htrg1 of the humidity of the fuel gas and the target value Htrg2 of the humidity of the oxidant gas (step S13).

Next, the humidifiers 147, 167 are controlled so as to achieve the target values Htrg1, Htrg2 (step S14).
Then, the control unit 90 terminates this series of processes.

On the other hand, when it is determined that the current density J has changed by a predetermined value or more (step S12: "NO"), the control unit 90 determines whether the read electrical resistance value Z is within a predetermined range (step S15).

Here, if it is determined that the electrical resistance value Z is within the predetermined range (step S15: "YES"), there is a high possibility that the amount of stagnant water in the oxidizing gas flow path 14a has hardly changed since the previous control cycle, so the process proceeds to step S13.

On the other hand, when it is determined that the electrical resistance value Z is not within the predetermined range (step S15: "NO"), the control unit 90 refers to the read map corresponding to the current density J, and sets the target values Htrg1 and Htrg2 based on the electrical resistance value Z (step S16). Then, the process proceeds to step S14.

Next, the operation of this embodiment will be described.
Based on the electrical resistance value Z and the current density J, the target humidity values Htrg1 and Htrg2 of the fuel gas and the oxidant gas passing through the humidifiers 147 and 167 are set. Then, the humidifiers 147 and 167 are controlled so that the humidity of the fuel gas and the humidity of the oxidizing gas detected by the humidity sensors 86 and 87 become the target values Htrg1 and Htrg2. Therefore, the humidifiers 147 and 167 can be controlled in accordance with the actual state of the accumulated water in the fuel cell 10 .

Next, the effects of this embodiment will be described.
(2-1) The control unit 90 is configured to set the humidity target values Htrg1 and Htrg2 of the fuel gas and the oxidizing gas passing through the humidifiers 147 and 167 based on the electrical resistance value Z and the current density J. The control unit 90 is configured to control the humidifiers 147 and 167 so that the humidity of the fuel gas and the oxidizing gas detected by the humidity sensors 86 and 87 become the target values Htrg1 and Htrg2.

According to such a configuration, the humidity of the fuel cell 10 can be appropriately adjusted because of the effects described above.
(2-2) The control unit 90 is configured to refer to the map to determine the target values Htrg1 and Htrg2, and to control the humidifiers 147 and 167 so that the humidity of the fuel gas and the oxidant gas reach the target values Htrg1 and Htrg2.

According to such a configuration, the target values Htrg1 and Htrg2 of the humidity of the fuel gas and the oxidant gas passing through the humidifiers 147 and 167 are determined by referring to maps stored in advance in the memory 91 of the control unit 90 . Then, the humidifiers 147 and 167 are controlled so that the humidity of the fuel gas and the oxidant gas reach the target values Htrg1 and Htrg2. Therefore, the humidifiers 147 and 167 can be easily controlled.

<Change example>
This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

- In the first embodiment, the humidifiers 47 and 67 are controlled based on all of the electric resistance value Z, the current density J, the pressure loss ΔP of the oxidizing gas, and the generated water volume V, but the present invention is not limited to this. The humidifiers 47 and 67 may be controlled based on two of the electric resistance value Z, the current density J, the pressure loss ΔP of the oxidizing gas, and the amount V of the generated water. Further, the humidifiers 47 and 67 may be controlled based on the electric resistance value Z, any one of the current density J, the pressure loss ΔP of the oxidizing gas, and the amount V of the generated water.

- In the first embodiment, the map is referenced to determine whether or not the accumulated water in the oxidizing gas flow path 14a is in a flooded state, but the present invention is not limited to this. For example, based on the electrical resistance value Z, the current density J, the pressure loss ΔP of the oxidizing gas, and the generated water amount V, it may be determined whether or not the accumulated water in the oxidizing gas flow path 14a is in a flooded state using a preset arithmetic expression.

In the second embodiment, the target value Htrg1 for the humidity of the fuel gas and the target value Htrg2 for the humidity of the oxidant gas are derived by referring to the map, but the present invention is not limited to this. For example, based on the electrical resistance value Z and the current density J, the target value Htrg1 for the humidity of the fuel gas and the target value Htrg2 for the humidity of the oxidizing gas may be derived using a preset arithmetic expression.

In each embodiment, the ohmmeter 81 detects the electrical resistance value Z of the entire fuel cell 10, but may detect the electrical resistance value Z of at least one single cell 12 out of the plurality of single cells 12.

- For the humidifiers 47 and 147 provided in the fuel gas supply passage 40, the control of the humidifiers exemplified in each embodiment or modified example may not be applied.
The humidifying device may be provided at least in the oxidizing gas supply passage 60, and the humidifying device may not be provided in the fuel gas supply passage 40.

DESCRIPTION OF SYMBOLS 10... Fuel cell 11... Cell stack 12... Single cell 13... Anode side separator 13a... Fuel gas channel 14... Cathode side separator 14a... Oxidant gas channel 15... Membrane electrode assembly 16, 17... End plate 21... Fuel gas supply manifold 22... Fuel gas discharge manifold 31... Oxidant gas supply manifold 32... Oxidant gas discharge manifold 40... Fuel gas supply passage 41... Main passage 4 2 Bypass passage 43 Fuel gas supply unit 44 Humidification valve 45 Humidifier 46 Bypass valve 47, 147 Humidifier 50 Fuel gas discharge passage 51 Gas-liquid separator 52 Circulation pump 53 Purge passage 54 Purge valve 60 Oxidant gas supply passage 61 Main passage 62 Bypass passage 63 Oxidant gas supply unit 64 Humidifier 65 Humidifier 66 Bypass valve 67 , 167... Humidifier 70... Oxidizing gas discharge passage 71... Gas-liquid separator 72... Circulation pump 73... Purge passage 74... Purge valve 81... Resistance meter (electric resistance value detector)
81A... External load 82... Ammeter (current density detector)
83 ... Supply side pressure sensor (pressure loss detection unit)
84 ... discharge side pressure sensor (pressure loss detection unit)
85 ... Water level sensor (generated water amount detection unit)
86 Humidity sensor 87 Humidity sensor (humidity detector)
90... Control part 91... Memory

Claims (6)

a fuel cell comprising an anode-side separator having a fuel gas channel through which a fuel gas flows, a cathode-side separator having an oxidizing gas channel through which an oxidizing gas flows, and a membrane electrode assembly sandwiched between the anode-side separator and the cathode-side separator;
a fuel gas supply passage connected to the fuel gas flow path for supplying fuel gas to the fuel gas flow path;
an oxidizing gas supply passage connected to the oxidizing gas flow path for supplying oxidizing gas to the oxidizing gas flow path;
a humidifying device provided in the oxidizing gas supply passage for humidifying the oxidizing gas;
a control unit configured to be able to control the humidifying device;
A fuel cell system comprising an electrical resistance value detection unit that detects an electrical resistance value of the fuel cell,
At least one of a current density detection unit that detects the current density of the fuel cell, a pressure loss detection unit that detects the pressure loss of the oxidant gas in the fuel cell, and a generated water amount detection unit that detects the amount of water generated in the fuel cell,
The control unit is configured to control the humidifying device based on at least one of the electrical resistance value, the current density, the pressure loss, and the generated water volume.
fuel cell system. The control unit is configured to control the humidifying device based on all of the electrical resistance value, the current density, the pressure loss, and the generated water volume.
The fuel cell system according to claim 1. The control unit has a memory that stores a map that defines the relationship between the electrical resistance value, the current density, the pressure loss, the amount of water generated, and a target control state of the humidification device. The target control state of the humidification device is determined by referring to the map, and the humidification device is controlled so as to achieve the target control state.
3. The fuel cell system according to claim 2. The oxidizing gas supply passage has a main passage provided with a humidifier and a bypass passage bypassing the humidifier and provided with a bypass valve,
The humidifying device includes the humidifier and the bypass valve,
The control unit is configured to perform driving control of the humidifier and opening/closing control of the bypass valve.
The fuel cell system according to any one of claims 1 to 3. The humidifying device has a humidity detection unit that detects the humidity of the oxidizing gas passing through the humidifying device,
The control unit is configured to set a target value of humidity of the oxidizing gas passing through the humidifying device based on the electric resistance value and the current density, and control the humidifying device so that the humidity of the oxidizing gas detected by the humidity detecting unit becomes the target value.
The fuel cell system according to claim 1. The control unit has a memory that defines the relationship between the electrical resistance value and the target value and stores a plurality of maps set for each magnitude of the current density. The target value is determined by referring to the map, and the humidifier is controlled to achieve the target value.
The fuel cell system according to claim 5.

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