Gas flow control device and method, and fuel cell system

Abstract

The gas flow control device (200) of the embodiment detects a state of a degassing pipe (8) that branches from the hydrogen recirculation pipe (6) and is capable of discharging a part of the anode off-gas to the outside. Also, the gas flow control device (200) selects one map from among a plurality of maps used in control of the flow rate adjusting ejector (104) in accordance with the state of the degassing pipe. Then, the operation of the flow rate adjusting ejector (104) is controlled on the basis of the selected map, whereby flow rate adjustment of the hydrogen-containing gas is performed.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to a gas flow control device and method, and a fuel cell system. BACKGROUND

[0002] A general solid polymer fuel cell has a cell stack in which a plurality of fuel cell single cells are stacked. Such a fuel cell generates electric energy from chemical energy possessed by a fuel gas by causing the fuel gas containing hydrogen and an oxygen-containing gas containing oxygen to chemically react within each cell stack.

[0003] A fuel cell single cell has a polymer electrolyte membrane and an anode and a cathode disposed in a manner of sandwiching the polymer electrolyte membrane. When power generation is performed, the above fuel gas is supplied to the anode, and the above oxygen-containing gas is supplied to the cathode.

[0004] The fuel gas discharged from the anode is generally referred to as anode off gas. The anode off gas generally contains unreacted hydrogen, and thus sometimes is supplied again to the fuel cell in order to effectively use the fuel gas.

[0005] On the other hand, if the recycling time of the anode off gas is long-term, the concentration of nitrogen contained in the anode off gas increases, and as a result, sometimes the voltage of the fuel cell decreases. Therefore, in the case where the anode off gas is circulated, sometimes a portion of the anode off gas is discharged by connecting a degassing pipe to a recirculation pipe and opening a degassing switching valve of the degassing pipe as needed, so that the pressure of the anode off gas is reduced.

[0006] In the fuel cell system having the above recirculation pipe and degassing pipe, if the state of the normal operation in which degassing is not performed and the state of the degassing operation in which degassing is performed are switched, the flow rates of the fuel gas and the anode off gas supplied to the fuel cell change. As a result, the pressure of the anode changes. In this way, when the pressure changes, generally, the flow rate of the fuel gas is adjusted in order to restore the changed pressure to the original pressure.

[0007] However, the operating conditions such as the pressure and the flow rate in the flow path are different between the normal operation and the degassing operation, and thus sometimes the control to the original pressure cannot be smoothly performed.

[0008] In addition, when the fuel cell is operated for a long time, although the pressure can be appropriately controlled in the past, sometimes the control to the desired pressure cannot be smoothly performed due to some reason. Such a phenomenon has a tendency to become significant at the time of the degassing operation.

[0009] PRIOR ART DOCUMENTS

[0010] PATENT DOCUMENTS

[0011] Patent Document 1: Japanese Patent Application Publication No. 2020-95800 SUMMARY

[0012] PROBLEMS TO BE SOLVED BY THE INVENTION

[0013] Therefore, the present application aims to provide a gas flow rate control device and method, and a fuel cell system, which can rapidly and accurately control a gas supply state to a fuel cell to a desired state even when switching of degassing of anode offgas is performed.

[0014] MEANS FOR SOLVING THE PROBLEMS

[0015] A gas flow rate control device according to one embodiment is a gas flow rate control device in a fuel cell system that supplies fuel gas, which has been flow rate-adjusted by a flow rate adjustment section, to a fuel cell and circulates anode offgas, which flows out from the fuel cell, in a recirculation pipe between the flow rate adjustment section and the fuel cell. The gas flow rate control device includes a detection section that detects a state of a degassing pipe that branches from the recirculation pipe and can discharge a part of the anode offgas to the outside, and a flow rate adjustment operation control section that selects one map from among a plurality of maps used in control of the flow rate adjustment section in accordance with the state of the degassing pipe detected by the detection section, and controls operation of the flow rate adjustment section based on the selected map, thereby performing flow rate adjustment of the fuel gas.

[0016] A gas flow rate control method according to one embodiment is a gas flow rate control method in a fuel cell system that supplies fuel gas, which has been flow rate-adjusted by a flow rate adjustment section, to a fuel cell and circulates anode offgas, which flows out from the fuel cell, in a recirculation pipe between the flow rate adjustment section and the fuel cell. The method includes a detection step of detecting a state of a degassing pipe that branches from the recirculation pipe and can discharge a part of the anode offgas to the outside, and a flow rate adjustment operation control step of selecting one map from among a plurality of maps used in control of the flow rate adjustment section in accordance with the state of the degassing pipe detected in the detection step, and controlling operation of the flow rate adjustment section based on the selected map, thereby performing flow rate adjustment of the fuel gas.

[0017] A fuel cell system according to one embodiment is a fuel cell system that supplies fuel gas, which has been flow rate-adjusted by a flow rate adjustment section, to a fuel cell and circulates anode offgas, which flows out from the fuel cell, in a recirculation pipe between the flow rate adjustment section and the fuel cell, in which the flow rate adjustment section is controlled by the gas flow rate control device.

[0018] EFFECTS OF THE INVENTION

[0019] According to the present application, even in the case where switching of degassing of anode off-gas is performed, the gas supply state to the fuel cell can be rapidly and highly accurately controlled to a desired state. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a diagram showing an outline structure of a fuel cell system provided with a gas flow rate control device of one embodiment.

[0021] Figure 2 is a block diagram showing a functional structure of a gas flow rate control device of one embodiment.

[0022] Figure 3 is a diagram showing an example of a map stored in a gas flow rate control device of one embodiment.

[0023] Figure 4 is a block diagram showing an example of a control model of a gas flow rate control device of one embodiment.

[0024] Figure 5 is a flowchart showing an example of the operation of a gas flow rate control device of one embodiment.

[0025] Figure 6 is a diagram showing the operation of a gas flow rate control device of one embodiment to update a map. DETAILED DESCRIPTION

[0026] Hereinafter, one embodiment will be described in detail with reference to the drawings.

[0027] Figure 1 is a diagram showing an outline structure of a fuel cell system 1 provided with a gas flow rate control device 200 of one embodiment.

[0028] <Overall Structure>

[0029] Figure 1 The fuel cell system 1 illustrated in the figure is a system capable of reusing anode off-gas that flows out from a fuel electrode of a fuel cell 100 in a power generation process. The fuel cell system 1 is provided with a hydrogen gas supply pipe 2, an oxygen gas supply pipe 4, a hydrogen recirculation pipe 6, a degassing pipe 8, the fuel cell 100, a hydrogen gas supply device 102, a flow rate adjustment injector 104, a recirculation blower 106, a degassing switching valve 108, a pressure sensor 110, a flow rate detection portion 112, and a gas flow rate control device 200.

[0030] The hydrogen supply pipe 2 is a pipe that connects the inlet portion Jl of the fuel electrode flow path 100a (anode electrode flow path in the figure) of the fuel cell 100 with the hydrogen supply device 102. The hydrogen supply device 102 is a device that supplies the stored fuel gas, i.e., hydrogen-containing gas, and can be, for example, a hydrogen tank or the like. In the present embodiment, the original pressure of the hydrogen-containing gas supplied from the hydrogen supply device 102, i.e., the fuel original pressure, is maintained at a constant value.

[0031] A flow rate adjustment ejector 104 is provided on the hydrogen supply pipe 2, and adjusts the flow rate of the hydrogen-containing gas from the hydrogen supply device 102 and supplies it to the fuel cell 100. In the present embodiment, the adjustment unit of the supply flow rate of the hydrogen-containing gas is the flow rate adjustment ejector 104, but other units, such as a flow rate adjustment valve or the like, can also be used.

[0032] The flow rate adjustment ejector 104 can adjust the flow rate of the hydrogen-containing gas supplied to the fuel cell 100, and can adjust the flow rate of the hydrogen-containing gas in accordance with the power generation amount of the fuel cell 100. In addition, a stop valve can also be provided on the upstream side of the flow rate adjustment ejector 104 in the hydrogen supply pipe 2.

[0033] The oxygen supply pipe 4 is a pipe that connects the inlet portion of the oxidizing agent electrode flow path 100b (cathode electrode flow path in the figure) in the fuel cell 100, and supplies the oxygen-containing gas to the oxidizing agent electrode flow path 100b of the fuel cell 100.

[0034] The hydrogen recirculation pipe 6 is a pipe that connects the outlet portion J2 of the fuel electrode flow path 100a in the fuel cell 100 with a merging portion J3 provided between the flow rate adjustment ejector 104 in the hydrogen supply pipe 2 and the fuel cell 100. This hydrogen recirculation pipe 6 circulates the anode exhaust gas flowing out from the fuel electrode flow path 100a via the merging portion J3 of the hydrogen supply pipe 2, and thereby can reuse the anode exhaust gas.

[0035] A recirculation blower 106 is provided on the hydrogen recirculation pipe 6, and the recirculation blower 106 introduces the anode exhaust gas from the fuel cell 100 into the hydrogen recirculation pipe 6, and thereby circulates the anode exhaust gas in the hydrogen supply pipe 2. The recirculation blower 106 can be, for example, a diaphragm pump, a Roots pump, a scroll pump, or the like.

[0036] The degassing pipe 8 is a pipe that branches from a branch portion J4 provided between the recirculation blower 106 and the merging portion J3 in the hydrogen recirculation pipe 6. A degassing switching valve 108 is provided on the degassing pipe 8, and by switching the degassing switching valve 108 from the closed state to the open state, a portion of the anode exhaust gas can be discharged to the outside from the degassing pipe 8.

[0037] The fuel cell 100 to which the hydrogen supply pipe 2 and the oxygen supply pipe 4 described above are connected has a fuel electrode flow path 100a that supplies hydrogen-containing gas to a fuel electrode (anode) and an oxidant electrode flow path 100b that supplies oxygen-containing gas to an oxidant electrode (cathode), and generates electricity using the hydrogen-containing gas supplied to the fuel electrode and the oxygen-containing gas supplied to the oxidant electrode. The oxygen-containing gas is, for example, atmospheric air. In the present embodiment, a load 300 is connected to the fuel cell 100, and the electric power generated by the fuel cell 100 can be supplied to the load 300. The load 300 can also be, for example, an electric motor or a storage battery, or the like.

[0038] Here, the anode exhaust gas described above is gas discharged from the fuel electrode flow path 100a during the electricity generation of the fuel cell 100, and generally contains unreacted hydrogen. On the other hand, nitrogen N2 in the oxygen-containing gas supplied to the oxidant electrode is mixed into the anode exhaust gas. Therefore, the nitrogen concentration of the anode exhaust gas (hydrogen H2 + nitrogen N2) in circulation increases over time, and conversely the hydrogen concentration in the anode exhaust gas decreases. The degassing pipe 8 described above is provided in order to restore the hydrogen concentration of the hydrogen-containing gas supplied to the fuel cell 100 by discharging the anode exhaust gas in which the impurity concentration has increased.

[0039] In addition, a pressure sensor 110 detects the pressure in the flow path between the flow rate adjustment ejector 104 in the hydrogen supply pipe 2 and the fuel cell 100. The pressure sensor 110 detects the pressure of the hydrogen-containing gas in the flow path of the hydrogen supply pipe 2, and transmits the detected information to the gas flow rate control device 200.

[0040] In addition, a flow rate detection section 112 detects the flow rate of the hydrogen-containing gas flowing in the hydrogen supply pipe 2. In detail, the flow rate detection section 112 detects the flow rate of the hydrogen-containing gas flowing in the portion between the flow rate adjustment ejector 104 and the confluence section J3 in the hydrogen supply pipe 2. Then, the flow rate detection section 112 transmits information on the detected flow rate of the hydrogen-containing gas to the gas flow rate control device 200. In the present embodiment, the flow rate detection section 112 is, for example, a mechanical flowmeter such as an impeller type, but the flow rate detection section 112 can also be constituted by software. In this case, for example, the flow rate detection section 112 can be constituted so as to predict the flow rate based on the operation condition (opening degree, opening / closing frequency) of the flow rate adjustment ejector 104, or can be constituted so as to predict the flow rate based on the indication value of the pressure sensor 110.

[0041] In addition, in the present embodiment, information on the amount of electricity generated by the fuel cell 100 during electricity generation is also transmitted to the gas flow rate control device 200. As the information on the amount of electricity generated, the output current of the fuel cell 100 can also be used.

[0042] <Gas flow rate control device>

[0043] Figure 2is a block diagram showing the functional configuration of the gas flow rate control device 200. The gas flow rate control device 200 is configured to adjust the flow rate of the hydrogen-containing gas supplied to the fuel cell 100 and control the pressure of the fuel gas supplied to the fuel cell 100 to a desired pressure.

[0044] The gas flow rate control device 200 includes a processor that reads and executes a required program from the storage section 202, thereby realizing various functions. The storage section 202 is realized by, for example, a semiconductor memory element such as a RAM (Random Access Memory), a flash memory, a hard disk, an optical disk, or the like. In addition, the processor such as a statement refers to a circuit such as a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), an SPLD (Programmable Logic Device), a CPLD (Complex Programmable Logic Device), an FPGA (Field Programmable Gate Array), or the like. In addition, instead of saving a program in the storage section 202, the processor can be configured to have the program directly incorporated in the circuit of the processor.

[0045] As shown in Figure 2 The gas flow rate control device 200 has the above-described storage section 202, the state detection section 204, the flow rate acquisition section 205, the power generation amount detection section 206, the pressure detection section 208, the flow rate adjustment operation control section 210, the anode off-gas discharge amount control section 212, the pressure control section 214, and the tuning section 216. The functional sections other than the storage section 202 are realized by executing the program called from the storage section 202.

[0046] The storage section 202 has a map holding section 202a that stores various programs and holds a plurality of maps used in the control of the flow rate adjustment ejector 104 and the like.

[0047] Figure 3 Examples of the maps stored in the map holding section 202a are shown, and specifically, examples of the normal-use maps Nfm, Nufm and the reference degassing-time maps Dfm, Dufm used in the control of the flow rate adjustment ejector 104 are shown. The normal-use maps Nfm, Nufm are maps used in a case where the anode off-gas is not discharged from the degassing pipe 8, that is, in a normal operation, and the reference degassing-time maps Dfm, Dufm are maps used in a case where the anode off-gas is discharged from the degassing pipe 8, that is, in a degassing operation.

[0048] Figure 3The upper side shows that the relationship between the power generation amount at which the fuel cell 100 is able to generate power and the flow rate of the hydrogen-containing gas supplied from the flow rate adjustment ejector 104 in order to obtain a prescribed power generation amount in the fuel cell 100 is determined by the normal use map Nfm and the reference degassing time map Dfm.

[0049] Figure 3 The lower side shows that the relationship between the power generation amount at which the fuel cell 100 is able to generate power and the fuel utilization of the hydrogen-containing gas supplied from the flow rate adjustment ejector 104 in order to obtain a prescribed power generation amount in the fuel cell 100 is determined by the normal use map Nufm and the reference degassing time map Dufm. Here, the fuel utilization refers to the proportion of the hydrogen-containing gas supplied from the flow rate adjustment ejector 104 that is used for power generation in the fuel cell 100. The fuel utilization is determined by the consumption amount of hydrogen / the flow rate of the supplied hydrogen-containing gas. The consumption amount of hydrogen can be calculated from the actual power generation amount of the fuel cell 100.

[0050] In the present embodiment, the normal use map Nfm and the reference degassing time map Dfm that determine the relationship between the power generation amount and the flow rate of the hydrogen-containing gas are used to control the flow rate adjustment ejector 104. Figure 3 The upper side shows that the flow rate adjustment ejector 104 is controlled using the normal use map Nfm and the reference degassing time map Dfm. That is, the fuel cell system 1 controls the flow rate of the hydrogen-containing gas supplied from the flow rate adjustment ejector 104 in order to obtain a certain power generation amount of the fuel cell 100. At this time, the normal use map Nfm and the reference degassing time map Dfm are referred to. Specifically, in the case where the degassing operation using the reference degassing time map Dfm is performed, the power generation amount X is specified as shown in the upper side, and the flow rate Y is determined by referring to the normal use map Dfm. Figure 3 The flow rate Y is determined by referring to the normal use map Dfm.

[0051] As is clear from the illustration of the normal use map Nfm and the reference degassing time map Dfm, the greater the specified power generation amount (in other words, the target power generation amount), the greater the flow rate of the hydrogen-containing gas supplied from the flow rate adjustment ejector 104 is set to be. On the other hand, the lower side shows that the relationship between the power generation amount and the fuel utilization of the hydrogen-containing gas is determined by the normal use map Nufm and the reference degassing time map Dufm. In the normal use map Nufm, the fuel utilization of the hydrogen-containing gas becomes a substantially constant value, and in the reference degassing time map Dufm, the greater the specified power generation amount, the greater the fuel utilization of the hydrogen-containing gas supplied from the flow rate adjustment ejector 104 is set to be, so that the flow rate adjustment ejector 104 is controlled in a manner that increases the fuel utilization. Figure 3 In the normal use map Nufm and the reference degassing time map Dufm shown on the lower side, in the case where the normal use map Nufm is used, the fuel utilization of the hydrogen-containing gas becomes a substantially constant value, and in the case where the reference degassing time map Dufm is used, the greater the specified power generation amount, the greater the fuel utilization of the hydrogen-containing gas supplied from the flow rate adjustment ejector 104 is set to be, so that the flow rate adjustment ejector 104 is controlled in a manner that increases the fuel utilization.

[0052] Returning to Figure 2The state detection section 204 detects the state of the degassing pipe 8, specifically, as the state of the degassing pipe 8, detects a state in which anode off-gas is not discharged from the degassing pipe 8 (normal operation), or a state in which anode off-gas is discharged from the degassing pipe 8 (degassing operation). The state detection section 204 can also detect the state of the degassing pipe 8 as described above based on the state of the degassing switching valve 108 that opens and closes the degassing pipe 8.

[0053] The flow rate acquisition section 205 acquires information of the flow rate of the hydrogen-containing gas from the flow rate detection section 112. Further, in the case where the flow rate detection section 112 is configured by software as described above, the flow rate detection section 112 can also be integrated with the flow rate acquisition section 205.

[0054] The power generation amount detection section 206 detects the actual power generation amount of the fuel cell 100 based on information of the power generation amount transmitted from the fuel cell 100 during power generation. Further, in calculating the fuel utilization, for example, the fuel consumption amount can be determined from the actual power generation amount of the fuel cell 100, and divided by the flow rate of the hydrogen-containing gas acquired by the flow rate acquisition section 205. However, the method of calculating the fuel utilization is not limited thereto.

[0055] The pressure detection section 208 detects the pressure in the flow path between the flow rate regulation ejector 104 and the fuel cell 100 in the hydrogen gas supply pipe 2 based on information from the pressure sensor 110.

[0056] Further, the flow rate regulation action control section 210 selects one of a plurality of maps used in the control of the flow rate regulation ejector 104 (a normal-use map Nfm and a degassing-time map Dfm) in accordance with the state of the degassing pipe 8 detected by the state detection section 204, and controls the action of the flow rate regulation ejector 104 based on the selected map, thereby performing the flow rate regulation of the hydrogen-containing gas.

[0057] Specifically, the flow rate regulation action control section 210 selects the normal-use map Nfm in the case of being in a state in which anode off-gas is not discharged from the degassing pipe 8, i.e., normal operation, and selects the degassing-time map Dfm in the case of being in a state in which anode off-gas is discharged from the degassing pipe 8, i.e., degassing operation. Further, the flow rate regulation action control section 210 determines the flow rate of the hydrogen-containing gas to control the flow rate regulation ejector 104 in accordance with the normal-use map Nfm or the degassing-time map Dfm selected, e.g., the specified power generation amount of the fuel cell 100.

[0058] Next, the anode off-gas discharge amount control section 212 controls the discharge amount of anode off-gas from the fuel cell 100 by controlling the recirculation blower 106. Specifically, the anode off-gas discharge amount control section 212 regulates the control amount of the recirculation blower 106 based on the blower control map stored in the map holding section 202a of the storage section 202.

[0059] The blower control map determines, for example, a relationship between the air volume (rotation speed) of the recirculation blower 106 and a certain power generation amount of the fuel cell 100. In addition, the anode off-gas discharge amount control section 212 controls the recirculation blower 106 by map control in the present embodiment, but can also control by PID control or the like.

[0060] In addition, the pressure control section 214 controls the action of the flow regulating ejector 104 in such a manner that the pressure detected by the pressure detection section 208 coincides with the target pressure by control based on the difference between the pressure detected by the pressure detection section 208 and the target pressure, in this case, by PID control. The above-mentioned target pressure is determined in accordance with the power generation amount of the fuel cell 100, and the relationship between the target pressure and the power generation amount can also be stored in advance in the storage section 202.

[0061] In this case, the flow regulating ejector 104 in the present embodiment performs flow regulation by map control based on the flow regulating action control section 210 and PID control based on the pressure control section 214. Figure 4 is a block diagram showing an example of a control model of the gas flow control device 200 for the flow regulating ejector 104.

[0062] As shown in Figure 4 , in the control of the flow regulating ejector 104, information on the power generation amount of the fuel cell 100 and the state of the degassing pipe 8 is input to the flow regulating action control section 210. On the other hand, information on the target pressure based on the power generation amount of the fuel cell 100 is input to the pressure control section 214. Then, the flow regulating action control section 210 performs feedforward control based on the selected map with respect to the flow regulating action control section 210. In addition, the pressure control section 214 performs feedback control based on PID with respect to the flow regulating action control section 210 based on the difference between the target pressure and the detected pressure. That is, in the present embodiment, the responsiveness of the control is improved by performing feedforward control corresponding to the change in the state of the degassing pipe 8.

[0063] The tuning section 216 will be described below. The tuning section 216 tunes the characteristics of the reference degassing-time map Dfm (or Dufm). The tuning section 216 starts the tuning action when the difference between the flow rate of hydrogen-containing gas (or the fuel utilization) determined from the reference degassing-time map Dfm with respect to the actual power generation amount of the fuel cell 100 detected by the power generation amount detection section 206 and the actual flow rate of hydrogen-containing gas (or the fuel utilization) obtained by the flow rate detection section 112 is equal to or greater than a predetermined tuning start reference value during the degassing operation.

[0064] Since the tuning step of the map Dfm for the reference degassing is the same as that of the map Dufm for the reference degassing, the tuning action related to the map Dfm for the reference degassing used in the present embodiment will be described below.

[0065] When the tuning action is started, the tuning section 216 stops the control action of the power generation amount of the currently specified fuel cell 100, but maintains the degassing operation. Thereafter, the tuning section 216 specifies a plurality of power generation amounts, and causes the flow rate adjustment action control section 210 to implement the flow rate control based on the map Dfm for the reference degassing corresponding to each power generation amount.

[0066] Then, the tuning section 216 acquires, for each of the specified power generation amounts, a difference between the flow rate of the hydrogen-containing gas determined in accordance with the map Dfm for the reference degassing with respect to the actual power generation amount of the fuel cell 100 detected by the power generation amount detection section 206 and the actual flow rate of the hydrogen-containing gas. Then, the tuning section 216 changes the map Dfm for the reference degassing based on the acquired plurality of differences of the flow rates, thereby generating a new map for the degassing.

[0067] As the tuning action, while the control action of the power generation amount of the fuel cell 100 required for the load 300 is implemented, only at the time when the degassing operation is implemented, a difference between the flow rate of the hydrogen-containing gas determined in accordance with the map Dfm for the reference degassing with respect to the actual power generation amount of the fuel cell 100 detected by the power generation amount detection section 206 and the actual flow rate of the hydrogen-containing gas is acquired, and after the difference of each of the specified power generation amounts can be acquired, the tuning section 216 changes the map Dfm for the reference degassing based on the acquired plurality of differences of the flow rates, thereby generating a new map for the degassing.

[0068] When the new map for the degassing is generated as described above, in the present embodiment, in a case where the flow rate of the hydrogen-containing gas determined in accordance with the map Dfm for the reference degassing with respect to the actual power generation amount has a tendency to be smaller than the actual flow rate of the hydrogen-containing gas, for example, the map Dfm for the reference degassing is changed in a direction in which the flow rate is increased. On the other hand, in a case where the flow rate of the hydrogen-containing gas determined in accordance with the map Dfm for the reference degassing with respect to the actual power generation amount has a tendency to be larger than the actual flow rate of the hydrogen-containing gas, for example, the map Dfm for the reference degassing is changed in a direction in which the flow rate is decreased.

[0069] Then, after the mapping at the time of the new degassing is generated as above, the tuning section 216 determines whether the variation amount of the reference degassing-time mapping Dfm and the new degassing-time mapping exceeds a first reference, whether it exceeds a second reference that is larger than the first reference, and whether it exceeds a third reference that is larger than the second reference. The comparison of the variation amount with the reference can be performed, for example, by comparing the average value of the difference in the flow rate with respect to a plurality of power generation amounts and the reference corresponding thereto, or by comparing the cumulative value of the difference in the flow rate with respect to a plurality of power generation amounts and the reference corresponding thereto.

[0070] Also, in the case where the variation amount of the reference degassing-time mapping Dfm and the new degassing-time mapping does not exceed the first reference, the tuning section 216 maintains the existing reference degassing-time mapping Dfm. On the other hand, in the case where the variation amount exceeds the first reference and does not exceed the second reference, the tuning section 216 sets the new degassing-time mapping as the new reference degassing-time mapping Dfm.

[0071] In addition, in the case where the variation amount of the reference degassing-time mapping Dfm and the new degassing-time mapping exceeds the second reference and does not exceed the third reference, the tuning section 216 maintains the existing reference degassing-time mapping Dfm, and tunes the control amount of the anode off-gas exhaust amount control section 212. At this time, the tuning section 216 tunes the control amount of the anode off-gas exhaust amount control section 212 by tuning the above-described blower control mapping.

[0072] The tuning of the blower control mapping is performed by gradually changing the blower control mapping while maintaining the degassing operation, for example, and is completed when a prescribed condition is satisfied. The prescribed condition can be, for example, a condition in which the difference between the flow rate of the hydrogen-containing gas determined from the reference degassing-time mapping Dfm with respect to the actual power generation amount of the fuel cell 100 and the actual flow rate of the hydrogen-containing gas is less than a prescribed value that is smaller than the above-described tuning start reference value.

[0073] Furthermore, if the tuning of the blower control mapping is completed as above, the tuned blower control mapping is held as a new blower control mapping in the storage section 202. The held new blower control mapping is used by the anode off-gas exhaust amount control section 212 at the time of the degassing operation thereafter. In addition, the new blower control mapping can be used at the time of the normal operation. Furthermore, the tuning section 216 in the mode of the present embodiment, in a state where the anode off-gas exhaust amount control section 212 controls using the new blower control mapping and the flow rate adjustment action control section 210 controls using the existing reference degassing-time mapping Dfm thereafter, performs the above-described tuning action with respect to the reference degassing-time mapping Dfm again.

[0074] That is, after the tuning of the blower control map, the tuning section 216 again acquires the difference between the flow rate of the hydrogen-containing gas determined in accordance with the reference degassing-time map Dfm with respect to the actual power generation amount of the fuel cell 100 detected by the power generation amount detection section 206 and the actual flow rate of the hydrogen-containing gas for each of the specified power generation amounts. Further, the tuning section 216 changes the reference degassing-time map Dfm based on the acquired plurality of the above-mentioned differences in flow rate, thereby generating a new degassing-time map, and compares the amount of change of the reference degassing-time map Dfm and the new degassing-time map with the first to third references again.

[0075] On the other hand, in the case where the amount of change of the reference degassing-time map Dfm and the new degassing-time map exceeds the third reference, the tuning section 216 displays a warning and / or stops the fuel cell system 1. In the present embodiment, a warning is displayed.

[0076] Further, the tuning section 216 starts the tuning operation described above in the case where the difference in flow rate is equal to or greater than the tuning start reference value, and on the other hand, has a tuning function of making a slight adjustment to the map even in the case where the difference in flow rate does not exceed the tuning start reference value.

[0077] Specifically, the tuning section 216 records the difference between the flow rate of the hydrogen-containing gas determined in accordance with the reference degassing-time map Dfm with respect to the actual power generation amount of the fuel cell 100 detected by the power generation amount detection section 206 and the actual flow rate of the hydrogen-containing gas even in the case where the difference in flow rate is less than the tuning start reference value. Further, in the case where the number of the recorded plurality of the above-mentioned differences is equal to or greater than a prescribed number, the tuning section 216 changes the reference degassing-time map Dfm based on the recorded plurality of the above-mentioned differences, thereby generating a new degassing-time map, and sets the new degassing-time map as a new reference degassing-time map Dfm.

[0078] The tuning section 216 described above is provided in order to restore the fuel cell system 1 to a state in which proper control can be implemented when the responsiveness and the accuracy are reduced in controlling the pressure of the anode to the desired pressure during the degassing operation. With such a tuning section 216, it is possible to achieve an improvement in reliability of the fuel cell system 1.

[0079] <Actions>

[0080] Next, an example of the operation of the gas flow rate control device 200 will be described. Figure 5 is a flowchart showing an example of the operation of the gas flow rate control device 200. Here, an example of the operation of the gas flow rate control device 200 after the switch from the normal operation to the degassing operation will be described.

[0081] In the case of switching to the degassing operation from the normal operation, information indicating the intention of switching to the degassing operation is sent from the state detection section 204 to the flow regulation action control section 210. Thus, in step S101, first, the flow regulation action control section 210 switches from the normal map Nfm and selects the reference degassing-time map Dfm.

[0082] Then, in step S102, the flow regulation action control section 210 determines the flow rate of the hydrogen-containing gas in accordance with the reference degassing-time map Dfm and the information of the power generation amount of the fuel cell 100.

[0083] Next, in step S103, the flow regulation action control section 210 controls the action of the flow regulation injector 104 so that the flow regulation injector 104 supplies the hydrogen-containing gas at the flow rate of the hydrogen-containing gas determined in step S102.

[0084] Further, in step S104, the pressure control section 214 controls the action of the flow regulation injector 104 so that the pressure detected by the pressure detection section 208 coincides with the target pressure.

[0085] After that, in step S105, the power generation amount detection section 206 detects the current power generation amount of the fuel cell 100 during power generation, and the flow rate acquisition section 205 acquires the flow rate of the hydrogen-containing gas from the flow rate detection section 112.

[0086] Next, in step S106, the tuning section 216 calculates the difference between the flow rate of the hydrogen-containing gas determined in accordance with the reference degassing-time map Dfm with respect to the actual power generation amount of the fuel cell 100 detected by the power generation amount detection section 206 and the actual flow rate of the hydrogen-containing gas.

[0087] Then, in step S107, the tuning section 216 determines whether or not the difference calculated in step S106 is equal to or greater than a tuning start reference value. In the determination in step S107, in the case where the difference is smaller than the tuning start reference value (No), it is determined that the reference degassing-time map Dfm is not abnormal, and the processing proceeds to step S108.

[0088] Then, in step S108, the tuning section 216 records the difference between the flow rate of the hydrogen-containing gas determined in accordance with the reference degassing-time map Dfm with respect to the actual power generation amount of the fuel cell 100 detected by the power generation amount detection section 206 and the actual flow rate of the hydrogen-containing gas.

[0089] Next, in step S109, the tuning section 216 determines whether or not the number of the differences recorded in step S108 is equal to or greater than a prescribed number. In the determination in step S109, in the case where the number of the differences recorded in step S108 is smaller than the prescribed number (No), the processing proceeds to step S110.

[0090] Then, in step S110, the switching to normal operation is monitored, and in the case where there is no switching to normal operation, the processing returns to step S101. In the case where the switching to normal operation is detected, the degassing operation is stopped (ends).

[0091] Further, in the determination in step S109, in the case where the number of differences recorded in step S108 is equal to or more than the prescribed number (Yes), the processing moves to step S111.

[0092] In this step S111, the tuning section 216 changes the reference degassing-time map Dfm based on the differences recorded in step S108, thereby generating a new degassing-time map, and sets (updates) the new degassing-time map as the new reference degassing-time map Dfm. Thereafter, in step S110, the switching to normal operation is monitored, and in the case where there is no switching to normal operation, the processing returns to step S101. At this time, in step S101, the new reference degassing-time map Dfm is used.

[0093] On the other hand, in step S107, in the case where it is determined that the difference is equal to or more than the tuning start reference value, it is determined that the reference degassing-time map Dfm has an abnormality, and the processing moves from step S108 to step S112. Then, the tuning section 216 starts the active tuning operation.

[0094] In the tuning operation, first, in step S112, the tuning section 216 acquires, for the specified plurality of power generations, the difference between the flow rate of hydrogen-containing gas determined according to the reference degassing-time map Dfm with respect to the actual power generation of the fuel cell 100 detected by the power generation amount detection section 206 and the actual flow rate of hydrogen-containing gas. That is, the fuel cell 100 is controlled to the plurality of power generations, and the state (difference in flow rate) of each power generation is acquired.

[0095] Next, in step S113, the tuning section 216 changes the reference degassing-time map Dfm based on the plurality of the above-mentioned differences in flow rate acquired in step S112, thereby generating a new degassing-time map.

[0096] Then, in step S114, the tuning section 216 determines whether or not the amount of change of the reference degassing-time map Dfm from the new degassing-time map exceeds a first reference. In the determination in step S114, in the case where the amount of change does not exceed the first reference (No), it is determined that the reference degassing-time map Dfm has no abnormality, and the processing moves to step S110, returning to the state before the tuning operation.

[0097] On the other hand, in the determination in step S114, in the case where the amount of change exceeds the first reference (Yes), the processing moves to step S115, and the tuning section 216 determines whether or not the amount of change exceeds a second reference.

[0098] Then, in the determination in step S115, in a case where the variation does not exceed the second criterion (No), the tuning section 216 sets the new degassing-time map as the new reference degassing-time map Dfm in step S116. Thereafter, the processing shifts to step S110, and returns to the state before the tuning operation.

[0099] On the other hand, in the determination in step S115, in a case where the variation exceeds the second criterion (Yes), the tuning section 216 determines whether the variation exceeds a third criterion in step S117.

[0100] In a case where the variation does not exceed the third criterion in the determination in step S117 (No), the tuning section 216 tunes the control amount (blower control map) of the anode exhaust gas discharge amount control section 212 in step S118. Thereafter, the tuning section 216 returns to step S112, and performs the operation for generating a new degassing-time map again.

[0101] On the other hand, in a case where the variation exceeds the third criterion in the determination in step S117 (Yes), the tuning section 216 displays a warning in step S119, and thereafter shifts to step S110, and returns to the state before the tuning operation. In a case where the variation exceeds the third criterion in the determination in step S117, it is determined that the abnormality of the current reference degassing-time map Dfm is significant. Therefore, the warning display in step S119 is performed, for example, with the purpose of prompting the system to stop.

[0102] Here, Figure 6 is a conceptual diagram illustrating an example of the operation in which the gas flow rate control device 200 updates the map. In Figure 6 , specifically, an example of the operation performed in steps S112 to S116 in Figure 5 is conceptually illustrated.

[0103] As shown in (A) of Figure 6 , in the gas flow rate control device 200, the normal map Nfm and the reference degassing-time map Dfm are stored in advance.

[0104] When the tuning operation is started, as shown in (B) of Figure 6 , for a plurality of power generation amounts, the difference between the flow rate of hydrogen-containing gas determined in accordance with the reference degassing-time map Dfm with respect to the actual power generation amount of the fuel cell 100 detected by the power generation amount detection section 206 and the actual flow rate of hydrogen-containing gas is obtained. In (B) of Figure 6 , the relationship between the actual power generation amount of the fuel cell 100 detected by the power generation amount detection section 206 and the flow rate of hydrogen-containing gas determined in accordance with the reference degassing-time map Dfm with respect to the actual power generation amount is connected with a solid line. On the other hand, Figure 6The Δ in (B) indicates a difference in flow rate. In addition, Figure 6 The Δ in (B) indicates a difference in flow rate. In addition,

[0105] Furthermore, in Figure 6 In (C), a new degassing map generated by changing the degassing map Dfm based on the plurality of differences in flow rate obtained by the tuning unit 216 is shown. Furthermore, when the amount of change of the reference degassing map Dfm and the new degassing map exceeds the first reference and is less than the second reference, as Figure 6 As shown in (D), the new degassing map is set as the new reference degassing map Dfm.

[0106] As explained above, the gas flow rate control device 200 of the present embodiment switches the selection of the normal operation map Nfm and the reference degassing map Dfm used in the control of the flow rate adjusting injector 104 according to the state of the gas supply pipe 8, and controls the operation of the flow rate adjusting injector 104 based on the selected map. Thereby, even in the case where the degassing of the anode off-gas is switched, the gas supply state with respect to the fuel cell 100 can be rapidly and highly accurately controlled to the desired state.

[0107] In addition, the reference degassing map Dfm can be appropriately tuned by the tuning unit 216, and thus when the responsiveness and the accuracy of the pressure control during the degassing operation are reduced, it is possible to return to a state where appropriate control can be performed. Thereby, it is possible to improve the reliability of the fuel cell system 1.

[0108] The above describes one embodiment, but the above-described embodiment is presented as an example and is not intended to limit the scope of the invention. The new embodiment can be implemented in other various ways, and various omissions, substitutions, and changes can be made within the scope of the gist of the invention. The above-described embodiment and other modifications are included in the scope or gist of the invention, and are included in the scope of the invention and equivalents thereof recited in the claims.

Claims

1. A gas flow control device that is a gas flow control device in a fuel cell system that supplies fuel gas, whose flow rate is regulated by a flow rate regulating section, to a fuel cell, and circulates anode exhaust gas, which flows out from the fuel cell, in a recirculation pipe between the flow rate regulating section and the fuel cell, the gas flow control device comprising: a detection section that detects a state of a degassing pipe that branches from the recirculation pipe and can discharge a part of the anode exhaust gas to the outside, and detects a state in which the anode exhaust gas is not discharged from the degassing pipe or a state in which the anode exhaust gas is discharged from the degassing pipe as the state of the degassing pipe; and a flow rate regulating operation control section that selects one map from among a plurality of maps used in control of the flow rate regulating section, according to the state of the degassing pipe detected by the detection section, and controls operation of the flow rate regulating section based on the selected map, thereby performing flow rate regulation of the fuel gas, the plurality of maps including at least: a first normal map that determines a relationship between power generation amount of the fuel cell and first flow rate of the fuel gas supplied by the flow rate regulating section; and a first reference degassing map that determines a relationship between power generation amount of the fuel cell and second flow rate of the fuel gas supplied by the flow rate regulating section, and that prescribes, for the same power generation amount of the fuel cell as the normal map, that the second flow rate is more than the first flow rate in at least a part of a range of the power generation amount, the flow rate regulating operation control section selecting the first normal map in a state in which the anode exhaust gas is not discharged from the degassing pipe, and selecting the first reference degassing map in a state in which the anode exhaust gas is discharged from the degassing pipe.

2. The gas flow control device of claim 1, wherein, The plurality of maps further include: a second normal map that determines fuel utilization of the fuel gas supplied by the flow rate regulating section as a fixed value with respect to power generation amount of the fuel cell; and a second reference degassing map that determines a relationship between power generation amount of the fuel cell and fuel utilization of the fuel gas supplied by the flow rate regulating section, the flow rate regulating operation control section selecting the second normal map in a state in which the anode exhaust gas is not discharged from the degassing pipe, and selecting the second reference degassing map in a state in which the anode exhaust gas is discharged from the degassing pipe.

3. The gas flow control device according to claim 1 or 2, wherein The detection section detects the state of the degassing pipe based on a state of a degassing switching valve that opens and closes the degassing pipe.

2. The gas flow control device according to claim 1, wherein the degassing switching valve is provided in the degassing pipe.

4. The gas flow control device of claim 3, wherein, The plurality of maps include a normal map used in a state where the anode off-gas is not discharged from the degassing pipe, and a reference degassing map used in a state where the anode off-gas is discharged from the degassing pipe, and the gas flow rate control device further includes a tuning unit that tunes the characteristics of the reference degassing map, the tuning unit performing the following actions: when the state of the degassing pipe is the state where the anode off-gas is discharged, the reference degassing map is used to control the flow rate adjusting unit by the flow rate adjusting control unit; for a plurality of power generation amounts, a difference between a flow rate or a fuel utilization of the fuel gas determined from the reference degassing map with respect to an actual power generation amount of the fuel cell detected during power generation and an actual flow rate or fuel utilization of the fuel gas is obtained; a new degassing map is generated by changing the reference degassing map based on the obtained plurality of differences; and in a case where a change amount of the reference degassing map and the new degassing map exceeds a first reference, the new degassing map is set as a new reference degassing map.

5. The gas flow control device of claim 4, wherein, The tuning unit tunes a control amount of an anode off-gas discharge amount control unit that controls a discharge amount of the anode off-gas flowing out of the fuel cell, in a case where the change amount of the reference degassing map and the new degassing map exceeds a second reference that is larger than the first reference.

6. The gas flow control device of claim 5, wherein, The anode off-gas discharge amount control unit controls the discharge amount of the anode off-gas by controlling a recirculation blower that introduces the anode off-gas into the recirculation pipe.

7. The gas flow control device of claim 6, wherein, The anode off-gas discharge amount control unit adjusts a control amount of the recirculation blower based on a blower control map, and the tuning unit tunes the control amount of the anode off-gas discharge amount control unit by tuning the blower control map, the blower control map tuned by the tuning unit being held as a new blower control map.

8. The gas flow control device of any one of claims 5 to 7, wherein, After the tuning unit tunes the control amount of the anode off-gas discharge amount control unit, the tuning unit performs the following processing: for a plurality of power generation amounts, a difference between a flow rate or a fuel utilization of the fuel gas determined from the reference degassing map with respect to an actual power generation amount of the fuel cell detected during power generation and an actual flow rate or fuel utilization of the fuel gas is obtained again; and a new degassing map is generated by changing the reference degassing map based on the obtained plurality of differences.

9. The gas flow control device of any one of claims 4 to 7, wherein, The tuning unit starts the tuning action when a difference between a flow rate or a fuel utilization of the fuel gas determined from the reference degassing map with respect to an actual power generation amount of the fuel cell detected during power generation and an actual flow rate or fuel utilization of the fuel gas is equal to or greater than a tuning start reference value, in a case where the state of the degassing pipe is the state where the anode off-gas is discharged and the fuel cell is generating power.

10. The gas flow control device of claim 9, wherein, The tuning section performs the following processing even in a case where the difference between the flow rate of the fuel gas or the fuel utilization determined from the map for the reference degassing time with respect to the actual power generation amount of the fuel cell detected during power generation and the actual flow rate of the fuel gas or the fuel utilization is less than the tuning start reference value: recording the difference between the flow rate of the fuel gas or the fuel utilization determined from the map for the reference degassing time with respect to the actual power generation amount of the fuel cell detected during power generation and the actual flow rate of the fuel gas or the fuel utilization at a plurality of points; when the number of the recorded plurality of the differences becomes a prescribed number or more, changing the map for the reference degassing time based on the recorded plurality of the differences, thereby generating a new map for the degassing time.

11. The gas flow control device of claim 5, wherein, in a case where the amount of change of the map for the reference degassing time and the new map for the degassing time exceeds a third reference value larger than the second reference value, the tuning section displays a warning and / or stops the fuel cell system.

12. The gas flow control device of any one of claims 1, 2, 4-7, 10-11, wherein, Further provided are a pressure detection section that detects the pressure in a flow path between the flow rate adjustment section and the fuel cell, and a pressure control section that controls the operation of the flow rate adjustment section so that the pressure detected by the pressure detection section coincides with a target pressure by PID control based on the difference between the pressure detected by the pressure detection section and the target pressure.

13. The gas flow control device of claim 12, wherein, The target pressure is determined in accordance with the power generation amount of the fuel cell.

14. A gas flow control method that is a gas flow control method in a fuel cell system that supplies fuel gas, whose flow rate is regulated by a flow rate regulating section, to a fuel cell and circulates anode exhaust gas, which flows out from the fuel cell, in a recirculation pipe between the flow rate regulating section and the fuel cell, the gas flow control method comprising: a detection step of detecting a state of a degassing pipe that branches from the recirculation pipe and can discharge a part of the anode exhaust gas to the outside, the state of the degassing pipe being detected as a state in which the anode exhaust gas is not discharged from the degassing pipe or a state in which the anode exhaust gas is discharged from the degassing pipe; and a flow rate regulating operation control step of selecting one map from among a plurality of maps used in control of the flow rate regulating section in accordance with the state of the degassing pipe detected in the detection step, and controlling operation of the flow rate regulating section based on the selected map, thereby performing flow rate regulation of the fuel gas, the plurality of maps including at least a first normal map that determines a relationship between power generation amount of the fuel cell and first flow rate of the fuel gas supplied by the flow rate regulating section, and a first reference degassing map that determines a relationship between power generation amount of the fuel cell and second flow rate of the fuel gas supplied by the flow rate regulating section, and that prescribes, for the same power generation amount of the fuel cell as the normal map, the second flow rate to be greater than the first flow rate in at least a part of a range of the power generation amount, in the flow rate regulating operation control step, the first normal map being selected in a state in which the anode exhaust gas is not discharged from the degassing pipe, and the first reference degassing map being selected in a state in which the anode exhaust gas is discharged from the degassing pipe.

15. A fuel cell system that supplies fuel gas, whose flow rate is regulated by a flow rate regulating section, to a fuel cell and circulates anode exhaust gas, which flows out from the fuel cell, in a recirculation pipe between the flow rate regulating section and the fuel cell, in the fuel cell system, the flow rate regulating section is controlled by the gas flow control apparatus according to any one of claims 1 to 13.

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