Control device for fuel cell system

Abstract

The invention relates to a control device for a fuel cell system. A control device (10) for a fuel cell system (12) is provided with: a request value acquisition unit (68) for acquiring an oxidant gas request value, which is the flow rate of oxidant gas to be supplied to a fuel cell stack (16); a pressure acquisition unit (70) that acquires, from the pressure sensor (60), the pressure of the oxidant gas flowing through the oxidant gas supply flow path (24); and a pressure calculation unit (74) that calculates a pressure change amount per predetermined time for the acquired pressure acquired by the pressure acquisition unit. And a supply amount estimation unit (78). The supply amount estimation unit estimates the supply amount of the oxidant gas supplied to the fuel cell stack on the basis of the pressure change amount, the capacity of the oxidant gas supply flow path, and the oxidant gas demand value (Va).

Description

Technical Field

[0001] The invention relates to a control device for a fuel cell system. Background Art

[0002] In recent years, in order to ensure that more people have access to appropriate, reliable, sustainable and advanced energy, research and development of fuel cell systems that contribute to energy efficiency have been carried out.

[0003] The fuel cell system comprises: a fuel cell that generates electricity using a fuel gas and an oxidant gas; an oxidant gas supply path that supplies the oxidant gas to the fuel cell; and an oxidant gas supply assembly (compressor) that supplies the oxidant gas to the oxidant gas path (for example, refer to Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2004-355890 Summary of the invention

[0007] Problems to be solved by the invention

[0008] A control device for a fuel cell system is desired that can accurately estimate the flow rate of oxidant gas supplied from an oxidant gas supply flow path to a fuel cell.

[0009] The object of the present invention is to solve the above-mentioned problems.

[0010] Solutions for solving problems

[0011] 14. The control device of claim 13, wherein the control device further comprises a control unit for controlling a fuel cell system, wherein the control unit comprises: a fuel cell that generates electricity using a fuel gas and an oxidant gas; an oxidant gas supply path that supplies the oxidant gas to the fuel cell; and an oxidant gas supply assembly that supplies the oxidant gas to the oxidant gas supply path. The control device of the fuel cell system comprises: a required value acquisition unit that acquires the oxidant gas flow rate to be supplied to the fuel cell, that is, the oxidant gas required value; a pressure acquisition unit that acquires the pressure of the oxidant gas flowing in the oxidant gas supply path from a pressure sensor; a pressure calculation unit that calculates the pressure change of the acquired pressure acquired by the pressure acquisition unit at each predetermined time; and a supply quantity estimation unit that estimates the supply quantity of the oxidant gas supplied to the fuel cell based on the capacity of the oxidant gas supply path, the pressure change, and the oxidant gas required value.

[0012] Effects of the Invention

[0013] According to the present invention, the flow rate of the oxidant gas supplied from the oxidant gas supply flow path to the fuel cell can be estimated with high accuracy.

[0014] The above-mentioned objects, features and advantages can be easily understood from the following description of the embodiments described with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram showing the structure of a fuel cell system according to one embodiment of the present invention.

[0016] Figure 2 : is a flowchart showing the processing of the control device of the fuel cell system.

[0017] Figure 3 This is an explanatory diagram showing the relationship between the timing chart of the oxidant gas supply assembly, the supply path sealing valve, and the exhaust path sealing valve, and the supply amount of the oxidant gas supplied to the fuel cell stack. DETAILED DESCRIPTION

[0018] A control device 10 of a fuel cell system 12 according to an embodiment of the present invention will be described below with reference to the drawings. Figure 1 1 is a schematic diagram showing the structure of the fuel cell system 12 according to the present embodiment. Figure 1 As shown, the fuel cell system 12 includes an oxidant gas supply unit 14 , a fuel cell stack (fuel cell) 16 , a supply path sealing valve 18 , a discharge path sealing valve 20 , a fuel gas supply unit 22 , and a control device 10 .

[0019] The oxidant gas supply assembly 14 is a device that supplies oxidant gas to the fuel cell stack 16 via the oxidant gas supply flow path 24. The oxidant gas supply assembly 14 is configured to be able to adjust the flow rate of the oxidant gas supplied to the oxidant gas supply flow path 24. The oxidant gas supply assembly 14 can use, for example, an air pump or a compressor, but is not limited thereto. The oxidant gas may also be air, but is not limited to air if it is a gas containing oxygen.

[0020] The fuel cell stack 16 generates electricity through an electrochemical reaction between a fuel gas and an oxidant gas. The fuel gas is not particularly limited as long as it is a gas containing hydrogen. The fuel cell stack 16 has a plurality of power generation cells 26. Each power generation cell 26 has a membrane electrode assembly 28 (MEA: Membrane Electrode Assembly) and a pair of separators 30 that sandwich the membrane electrode assembly 28. The membrane electrode assembly 28 has, for example, an electrolyte membrane 32 that is a thin film of perfluorosulfonic acid containing water, a cathode electrode 34 that sandwiches the electrolyte membrane 32, and an anode electrode 36.

[0021] An oxidant gas flow path 38 is formed on one side of the pair of separators 30 on the surface facing the membrane electrode assembly 28. The oxidant gas flow path 38 is connected to the oxidant gas inlet 40 and the oxidant gas outlet 42 of the fuel cell stack 16. The oxidant gas inlet 40 is connected to the oxidant gas supply flow path 24, and the oxidant gas outlet 42 is connected to the oxidant gas exhaust flow path 44.

[0022] A fuel gas flow path 46 is formed on the other side of the pair of separators 30 on the surface facing the membrane electrode assembly 28. The fuel gas flow path 46 is connected to a fuel gas inlet 48 and a fuel gas outlet 50 of the fuel cell stack 16. The fuel gas inlet 48 is connected to a fuel gas supply flow path 52, and the fuel gas outlet 50 is connected to a fuel gas exhaust flow path 54.

[0023] In each power generation unit cell 26, a portion of the oxidant gas supplied to the oxidant gas flow path 38 chemically reacts with the fuel gas supplied to the fuel gas flow path 46. A mixed gas including the oxidant gas that has not chemically reacted and water (steam) generated by the chemical reaction is recovered as exhaust gas and discharged from the oxidant gas outlet portion 42 to the oxidant gas discharge flow path 44. The oxidant gas discharged to the oxidant gas discharge flow path 44 is discharged from the oxidant gas discharge flow path 44 to the atmosphere.

[0024] The supply path sealing valve 18 is provided in the oxidant gas supply flow path 24. The supply path sealing valve 18 opens and closes the oxidant gas supply flow path 24 under the control of the control device 10. The supply path sealing valve 18 may be a valve capable of either opening or closing, or a valve capable of adjusting the opening degree.

[0025] The discharge path sealing valve 20 is provided in the oxidant gas discharge flow path 44. The discharge path sealing valve 20 opens and closes the oxidant gas discharge flow path 44 according to the control of the control device 10. The discharge path sealing valve 20 may be a valve capable of opening or closing, or a valve capable of adjusting the opening. In the present embodiment, the discharge path sealing valve 20 is a valve capable of adjusting the opening.

[0026] The fuel gas supply assembly 22 is provided in the fuel gas supply flow path 52. The fuel gas supply assembly 22 is a device that supplies fuel gas to the fuel cell stack 16 via the fuel gas supply flow path 52. The fuel gas supply assembly 22 is configured to be able to adjust the flow rate of the fuel gas supplied to the fuel gas supply flow path 52. The fuel gas supply assembly 22 includes an injector.

[0027] The fuel cell system 12 may include various devices such as a bypass flow path connecting the oxidant gas supply flow path 24 and the oxidant gas exhaust flow path 44 to each other, a bypass valve for opening and closing the bypass flow path, and a humidifier for humidifying the oxidant gas.

[0028] In such a fuel cell system 12, the oxidant gas is supplied from the oxidant gas supply assembly 14 to the oxidant gas inlet 40 of the fuel cell stack 16 via the oxidant gas supply passage 24. The oxidant gas supplied to the oxidant gas inlet 40 is supplied to the cathode electrode 34 via the oxidant gas passage 38 of each power generation cell 26.

[0029] On the other hand, the fuel gas is supplied from the fuel gas supply assembly 22 to the fuel gas inlet 48 of the fuel cell stack 16 via the fuel gas supply passage 52. The fuel gas supplied to the fuel gas inlet 48 is supplied to the anode electrode 36 via the fuel gas passage 46 of each power generation cell 26. Each power generation cell 26 generates electricity using the oxidant gas supplied to the cathode electrode 34 and the fuel gas supplied to the anode electrode 36.

[0030] The oxidant gas flowing through the oxidant gas flow path 38 is discharged from the oxidant gas outlet portion 42 to the oxidant gas discharge flow path 44. The fuel gas flowing through the fuel gas flow path 46 is discharged from the fuel gas outlet portion 50 to the fuel gas discharge flow path 54.

[0031] The pressure sensor 60 and the temperature sensor 62 are connected to the control device 10. The pressure sensor 60 is provided in the oxidant gas supply flow path 24. The pressure sensor 60 detects the pressure of the oxidant gas flowing in the oxidant gas supply flow path 24. Specifically, the pressure sensor 60 is provided on both the upstream side and the downstream side of the supply path sealing valve 18 in the oxidant gas supply flow path 24. In this case, even if any one of the two pressure sensors 60 fails, the pressure of the oxidant gas flowing in the oxidant gas supply flow path 24 can be detected. In addition, it is also possible that the pressure sensor 60 is provided only on either the upstream side or the downstream side of the supply path sealing valve 18 in the oxidant gas supply flow path 24. The temperature sensor 62 is provided in the oxidant gas supply flow path 24. The temperature sensor 62 detects the temperature of the oxidant gas flowing in the oxidant gas supply flow path 24. The temperature sensor 62 is provided on the upstream side compared to the supply path sealing valve 18 in the oxidant gas supply flow path 24. Furthermore, the temperature sensor 62 may be provided on the downstream side of the supply path sealing valve 18 in the oxidizing gas supply flow path 24 , or may be provided on both the upstream side and the downstream side of the supply path sealing valve 18 .

[0032] The control device 10 includes a computing unit 64 and a storage unit 66. The computing unit 64 is composed of a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), that is, a processing circuit.

[0033] The operation unit 64 includes a demand value acquisition unit 68, a pressure acquisition unit 70, a temperature acquisition unit 72, a pressure calculation unit 74, a determination unit 76, a supply amount estimation unit 78, a target current value calculation unit 79, a demand value calculation unit 80, an oxidant gas control unit 81, and a fuel gas control unit 82. The demand value acquisition unit 68, the pressure acquisition unit 70, the temperature acquisition unit 72, the pressure calculation unit 74, the determination unit 76, the supply amount estimation unit 78, the target current value calculation unit 79, the demand value calculation unit 80, the oxidant gas control unit 81, and the fuel gas control unit 82 can be realized by the operation unit 64 executing a program stored in the storage unit 66.

[0034] Furthermore, at least a part of the required value acquisition unit 68, the pressure acquisition unit 70, the temperature acquisition unit 72, the pressure calculation unit 74, the determination unit 76, the supply amount estimation unit 78, the target current value calculation unit 79, the required value calculation unit 80, the oxidant gas control unit 81, and the fuel gas control unit 82 may be implemented by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Progra mmable Gate Array). In addition, at least a part of the required value acquisition unit 68, the pressure acquisition unit 70, the temperature acquisition unit 72, the pressure calculation unit 74, the determination unit 76, the supply amount estimation unit 78, the target current value calculation unit 79, the required value calculation unit 80, the oxidant gas control unit 81, and the fuel gas control unit 82 may be formed by a circuit including discrete devices.

[0035] The storage unit 66 is composed of a volatile memory (not shown) and a non-volatile memory (not shown). Examples of volatile memory include RAM (Random Access Memory). Volatile memory is used as a working memory of a processor to temporarily store data required for processing or calculation. Examples of non-volatile memory include ROM (Read Only Memory) and flash memory. Non-volatile memory is used as a storage memory to store programs, forms, mapping tables, etc. The processor, integrated circuit, etc. mentioned above may also include at least a part of the storage unit 66.

[0036] The required value acquisition unit 68 acquires the oxidant gas flow rate to be supplied to the fuel cell stack 16, that is, the oxidant gas required value. The pressure acquisition unit 70 acquires the pressure of the oxidant gas flowing in the oxidant gas supply flow path 24 from the pressure sensor 60. The pressure sensor 60 outputs a detection signal (analog signal or digital signal) of a size corresponding to the pressure of the oxidant gas to the control device 10. In this case, the pressure acquisition unit 70 calculates the pressure of the oxidant gas based on the output signal from the pressure sensor 60. It is also possible that the pressure sensor 60 calculates the pressure based on the detection value and outputs the calculated pressure to the control device 10. In this case, the pressure acquisition unit 70 directly acquires the pressure output from the pressure sensor 60 as the pressure of the oxidant gas. The pressure acquisition unit 70 acquires the pressure of the oxidant gas at a predetermined time interval. The acquired pressure acquired by the pressure acquisition unit 70 is stored in the storage unit 66.

[0037] The temperature acquisition unit 72 acquires the temperature of the oxidant gas flowing in the oxidant gas supply flow path 24 from the temperature sensor 62. The temperature sensor 62 outputs a detection signal (analog signal or digital signal) of a magnitude corresponding to the temperature of the oxidant gas to the control device 10. In this case, the temperature acquisition unit 72 calculates the temperature of the oxidant gas based on the output signal from the temperature sensor 62. Alternatively, the temperature sensor 62 calculates the temperature based on the detection value and outputs the calculated temperature to the control device 10. In this case, the temperature acquisition unit 72 directly acquires the temperature output from the temperature sensor 62 as the temperature of the oxidant gas.

[0038] The pressure calculation unit 74 calculates the pressure change amount (pressure difference) of the acquired pressure at each predetermined time. The pressure calculation unit 74 calculates the pressure change amount by, for example, subtracting the previously acquired pressure from the previously acquired pressure. Alternatively, the pressure calculation unit 74 may calculate the pressure change amount by subtracting the previously acquired pressure from the currently acquired pressure.

[0039] The determination unit 76 determines the change (increase, decrease, or fixation) of the target power generation amount of the fuel cell stack 16. The supply amount estimation unit 78 estimates the supply amount of the oxidant gas supplied to the fuel cell stack 16 based on the capacity of the oxidant gas supply flow path 24, the oxidant gas required value, and the pressure change amount. The target current value calculation unit 79 calculates the target current value of the fuel cell stack 16 based on the estimated value of the oxidant gas supply amount calculated by the supply amount estimation unit 78. The required value calculation unit 80 calculates the flow rate of the fuel gas to be supplied to the fuel cell stack 16 based on the target current value calculated by the target current value calculation unit 79.

[0040] The oxidant gas control unit 81 drives the oxidant gas supply unit 14, the supply path sealing valve 18, and the discharge path sealing valve 20 based on the oxidant gas demand value. The fuel gas control unit 82 drives the fuel gas supply unit 22 based on the supply amount of the oxidant gas estimated by the supply amount estimation unit 78.

[0041] Figure 2 1 is a flowchart showing the procedure of the process of the control device 10 of the fuel cell system 12. This process is executed in a predetermined cycle during the power generation from the start of the power generation operation of the fuel cell stack 16 to the stop.

[0042] like Figure 2 As shown, in step S1, the control device 10 obtains the target power generation amount of the fuel cell stack 16. The target power generation amount can be obtained from, for example, a higher-level control device (not shown). Thereafter, the process proceeds to step S2.

[0043] In step S2, the required value acquisition unit 68 acquires the oxidant gas required value. The required value acquisition unit 68 can calculate the oxidant gas required value based on the acquired target power generation. Alternatively, the oxidant gas required value may be calculated by the upper control device. In this case, the required value acquisition unit 68 acquires the oxidant gas required value from the upper control device. The acquired oxidant gas required value is stored in the storage unit 66. Thereafter, the process proceeds to step S3.

[0044] In step S3, the pressure acquisition unit 70 acquires the pressure of the oxidizing gas flowing through the oxidizing gas flow path 38 from the pressure sensor 60. The acquired pressure is stored in the storage unit 66. Thereafter, the process proceeds to step S4.

[0045] In step S4, the pressure calculation unit 74 calculates the pressure change amount per predetermined time of the acquired pressure acquired by the pressure acquisition unit 70. The calculated pressure change amount is stored in the storage unit 66. Thereafter, the process proceeds to step S5.

[0046] In step S5, the temperature acquisition unit 72 acquires the temperature of the oxidizing gas flowing through the oxidizing gas flow path 38 from the temperature sensor 62. The acquired temperature is stored in the storage unit 66. Thereafter, the process proceeds to step S6.

[0047] In step S6, the determination unit 76 determines the change in the target power generation amount. Specifically, when the target power generation amount is within the steady-state power generation range, the determination unit 76 determines that the target power generation amount is fixed. In addition, when the target power generation amount is greater than the previous target power generation amount, the determination unit 76 determines that the target power generation amount is increased. In addition, when the target power generation amount is less than the previous target power generation amount, the determination unit 76 determines that the target power generation amount is decreased. When the determination unit 76 determines that the target power generation amount is increased, the process moves to step S7.

[0048] In step S7, the oxidant gas control unit 81 drives the oxidant gas supply assembly 14, the supply path sealing valve 18, and the exhaust path sealing valve 20 based on the oxidant gas requirement value to increase the amount of oxidant gas supplied to the fuel cell stack 16. Figure 3 As shown, the oxidant gas control unit 81 increases the rotation speed of the oxidant gas supply assembly 14 and fully opens the supply path sealing valve 18. In addition, the oxidant gas control unit 81 opens the discharge path sealing valve 20 at a predetermined opening. The opening area of ​​the supply path sealing valve 18 is larger than the opening area of ​​the discharge path sealing valve 20.

[0049] When the rotation speed of the oxidant gas supply assembly 14 increases, the pressure of the oxidant gas in the oxidant gas supply flow path 24 increases. However, a portion of the oxidant gas supplied from the oxidant gas supply assembly 14 is not guided to the fuel cell stack 16, and the pressure of the oxidant gas in the oxidant gas supply flow path 24 increases. Therefore, the supply amount of oxidant gas supplied from the oxidant gas supply flow path 24 to the fuel cell stack 16 is less than the supply amount of oxidant gas supplied from the oxidant gas supply assembly 14 to the oxidant gas supply flow path 24. In other words, the actual supply amount of oxidant gas supplied to the fuel cell stack 16 is less than the required value of oxidant gas.

[0050] In this case, for example, when the fuel gas in an amount corresponding to the oxidant gas requirement value is supplied to the fuel cell stack 16, the oxidant gas supply amount is insufficient compared to the oxidant gas supply amount required for the set air-fuel ratio in each power generation cell 26. In other words, more fuel gas than the fuel gas required for the set air-fuel ratio is supplied to each power generation cell 26. In this way, the current of the fuel cell stack 16 cannot be limited accurately.

[0051] In order to solve such a problem, in the present embodiment, in step S8, the supply amount estimation unit 78 estimates the first supply amount V1 of the oxidant gas supplied to the fuel cell stack 16. Specifically, the supply amount estimation unit 78 estimates the first supply amount V1 of the oxidant gas according to the following formula.

[0052]

[0053] In the above formula, Va represents the oxidant gas requirement value, ΔP represents the pressure change amount, Vb represents the capacity of the oxidant gas supply flow path 24, R represents the gas constant, T represents the temperature of the oxidant gas, and m represents the mass of the oxidant gas per 1 mole. Va uses the oxidant gas requirement value acquired by the requirement value acquisition unit 68. ΔP uses the pressure change amount calculated by the pressure calculation unit 74. T uses the temperature acquired by the temperature acquisition unit 72. R and m are constants and are stored in the storage unit 66. Vb is a value determined according to the length, size, shape, etc. of the oxidant gas supply flow path 24 of the fuel cell system 12, and is stored in the storage unit 66.

[0054] exist Figure 3 In FIG. 1 , the line segment La represents the change of the oxidant gas required value Va, and the line segment Lb represents the change of the first supply amount V1 of the oxidant gas calculated according to the above formula. Figure 3 As shown, the first supply amount V1 of the oxidant gas estimated by the supply amount estimating unit 78 is smaller than the required oxidant gas value Va.

[0055] Furthermore, in the above step S7, Figure 2 In the periodic control of the flowchart, the oxidant gas control unit 81 continuously increases the rotation speed of the oxidant gas supply assembly 14 until the first supply amount V1 of the oxidant gas reaches the set supply amount V2. In addition, the oxidant gas control unit 81 fully opens the supply path sealing valve 18 from the start of driving the oxidant gas supply assembly 14 until the first supply amount V1 of the oxidant gas reaches the set supply amount V2. In addition, the oxidant gas control unit 81 opens the exhaust path sealing valve 20 with a first opening degree D1 until the first supply amount V1 of the oxidant gas reaches a predetermined threshold value V3. In addition, the oxidant gas control unit 81 gradually reduces the opening degree of the exhaust path sealing valve 20 from the time when the first supply amount V1 of the oxidant gas reaches the predetermined threshold value V3 until it reaches the set supply amount V2. At the time point when the first supply amount V1 reaches the set supply amount V2, the opening degree of the exhaust path sealing valve 20 is the second opening degree D2. After step S8, transfer to step S9.

[0056] like Figure 2 As shown, in step S9, the required value calculation unit 80 calculates the fuel gas flow rate to be supplied to the fuel cell stack 16, that is, the first fuel gas required value, based on the first supply amount V1 of the oxidant gas. Specifically, the target current value calculation unit 79 calculates the first target current value (limited current value) based on the first supply amount V1 of the oxidant gas. In addition, the required value calculation unit 80 calculates the first fuel gas required value based on the first target current value calculated by the target current value calculation unit 79. Thereafter, the process moves to step S10.

[0057] In step S10, the fuel gas control unit 82 drives the fuel gas supply assembly 22 based on the first fuel gas requirement value, and supplies the fuel gas in an amount corresponding to the first target current value calculated based on the first supply amount V1 of the oxidant gas to the fuel cell stack 16. In this case, the fuel gas control unit 82 controls the supply amount of the fuel gas so that the current value of the fuel cell stack 16 does not exceed the first target current value. As a result, in each power generation cell 26, since the oxidant gas and fuel gas at the flow rate required for the set air-fuel ratio are supplied, the current of the fuel cell stack 16 can be limited with good accuracy. Thereafter, Figure 2 The indicated processing is completed.

[0058] In step S6 , when the determination unit 76 determines that the target power generation amount is fixed, the process proceeds to step S11 .

[0059] In step S11, the oxidant gas control unit 81 drives the oxidant gas supply unit 14 based on the oxidant gas required value Va to keep the supply amount of oxidant gas supplied to the fuel cell stack 16 constant. Figure 3 As shown, the oxidizing gas control unit 81 keeps the rotation speed of the oxidizing gas supply unit 14 constant. In this case, the supply path sealing valve 18 is maintained fully open, and the discharge path sealing valve 20 is maintained at the second opening degree D2.

[0060] In such a steady power generation state, since the pressure of the oxidant gas in the oxidant gas flow path 38 does not increase, there is no significant difference between the oxidant gas demand value Va and the actual amount of oxidant gas supplied to the fuel cell stack 16. After step S11, the process proceeds to step S12.

[0061] In step S12, the required value calculation unit 80 calculates the fuel gas flow rate to be supplied to the fuel cell stack 16, that is, the second fuel gas required value, based on the oxidant gas required value Va. Specifically, the target current value calculation unit 79 calculates the second target current value based on the oxidant gas required value Va. In addition, the required value calculation unit 80 calculates the second fuel gas required value based on the second target current value calculated by the target current value calculation unit 79. Thereafter, the process moves to step S13.

[0062] In step S13, the fuel gas control unit 82 drives the fuel gas supply unit 22 based on the second fuel gas required value, so that the fuel gas of the amount corresponding to the oxidant gas required value Va is supplied to the fuel cell stack 16. Figure 2 The indicated processing is completed.

[0063] In step S6 , when the determination unit 76 determines that the target power generation amount is reduced, the process proceeds to step S14 .

[0064] In step S14, the oxidant gas control unit 81 drives the oxidant gas supply assembly 14 and the exhaust path sealing valve 20 based on the oxidant gas required value Va to reduce the amount of oxidant gas supplied to the fuel cell stack 16. Figure 3 As shown, the oxidant gas control unit 81 reduces the rotation speed of the oxidant gas supply unit 14 and increases the opening of the discharge passage sealing valve 20 from the second opening D2 to the first opening D1. The supply passage sealing valve 18 is maintained fully open.

[0065] When the rotation speed of the oxidant gas supply assembly 14 decreases, the flow rate of the oxidant gas supplied from the oxidant gas supply assembly 14 to the oxidant gas flow path 38 decreases and the pressure decreases. As a result, the amount of oxidant gas supplied to the fuel cell stack 16 increases due to the pressure reduction in the oxidant gas flow path 38. In addition, since the oxidant gas is also supplied from the oxidant gas supply assembly 14, the amount of oxidant gas supplied to the fuel cell stack 16 is greater than the oxidant gas required value Va. In particular, when the oxidant gas supply assembly 14 is an air pump, the pressure reduction rate of the air pump needs to be increased to avoid surging of the air pump, and the actual amount of oxidant gas supplied to the fuel cell stack 16 is greater than the oxidant gas required value Va.

[0066] In this case, for example, when the fuel gas in an amount corresponding to the oxidant gas required value Va is supplied to the fuel cell stack 16, the oxidant gas supply amount is greater than the oxidant gas supply amount required for setting the air-fuel ratio in each power generation cell 26. Thus, the current cannot be limited accurately by calculating the target current value of the fuel cell stack 16 based only on the oxidant gas required value Va.

[0067] In order to solve such a problem, in the present embodiment, in step S15, the supply amount estimation unit 78 estimates the second supply amount of the oxidant gas supplied to the fuel cell stack 16. Specifically, the supply amount estimation unit 78 estimates the second supply amount based on the above formula. In this case, since the pressure of the oxidant gas supply flow path 24 is added to the above formula, the flow rate of the oxidant gas supplied to the fuel cell stack 16 can be accurately estimated.

[0068] exist Figure 3 In FIG. 1 , line segment Lc represents the change in the estimated value of the inflow amount of the oxidant gas supplied to the fuel cell stack 16 when the delay control as a comparative example is implemented, and line segment Ld represents the change in the second supply amount calculated based on the above formula and the acquired pressure. Line segment Le represents the change in the oxidant gas required value Va.

[0069] It can be estimated that when the delay control is implemented to delay the oxidant gas required value Va by a predetermined time, the flow rate of the oxidant gas supplied to the fuel cell stack 16 will be less than the oxidant gas required value Va when the target power generation increases. However, it can be estimated that when the delay control is implemented when the target power generation decreases, an amount of oxidant gas greater than the oxidant gas required value Va (line segment Le) will be supplied to the fuel cell stack 16. The supply amount estimated by the delay control is greater than the actual supply amount of the oxidant gas.

[0070] In contrast, the second supply amount (line segment Ld) becomes a flow rate (appropriate flow rate) close to the actual supply amount of the oxidant gas. In addition, the supply amount estimated based on the delay control is an amount obtained by uniformly delaying the oxidant gas required value Va by only a predetermined time, so an amount greater than the oxidant gas required value Va is uniformly estimated in the delay control. On the other hand, the supply amount estimation unit 78 can estimate the second supply amount in a manner that makes the second supply amount variably change relative to the oxidant gas required value Va. Therefore, even when the target power generation decreases, the second supply amount can be estimated to be a value close to the actual oxidant gas supply amount. After step S15, transfer to step S16.

[0071] In step S16, the required value calculation unit 80 calculates the fuel gas flow rate to be supplied to the fuel cell stack 16, i.e., the third fuel gas required value, based on the second supply amount of the oxidant gas. Specifically, the target current value calculation unit 79 calculates the third target current value (limited current value) based on the second supply amount of the oxidant gas. In addition, the required value calculation unit 80 calculates the third fuel gas required value based on the third target current value calculated by the target current value calculation unit 79. Thereafter, the process moves to step S17.

[0072] In step S17, the fuel gas control unit 82 drives the fuel gas supply assembly 22 based on the third fuel gas requirement value, and supplies the fuel gas in an amount corresponding to the third target current value calculated based on the second supply amount of the oxidant gas to the fuel cell stack 16. In this case, the fuel gas control unit 82 controls the supply amount of the fuel gas so that the current value of the fuel cell stack 16 does not exceed the third target current value. As a result, in each power generation cell 26, since the oxidant gas and fuel gas at the flow rate required to set the air-fuel ratio are supplied, the current of the fuel cell stack 16 can be limited with good accuracy. Thereafter, Figure 2 The indicated processing is completed.

[0073] The processing of the control device 10 is not limited to the above-mentioned flowchart. The acquisition of the temperature of the oxidant gas (step S5) may also be performed before step S3, or may be performed simultaneously with step S3 or step S4. Alternatively, when the fuel cell system 12 is provided in a vehicle, in step S6, the determination unit 76 determines the change in the target power generation based on the state of the vehicle. In this case, when the acceleration of the vehicle is greater than the acceleration threshold, the determination unit 76 determines that the target power generation has increased. In addition, when the deceleration of the vehicle is greater than the deceleration threshold, the determination unit 76 determines that the target power generation has decreased. In addition, when the acceleration of the vehicle is below the acceleration threshold, when the deceleration of the vehicle is below the deceleration threshold, and when the acceleration of the vehicle is 0 (when the vehicle is traveling at a fixed speed or stopped), the determination unit 76 determines that the target power generation is fixed.

[0074] Alternatively, when the determination unit 76 determines in step S6 that the target power generation is fixed, the supply amount estimation unit 78 estimates the supply amount of the oxidant gas supplied to the fuel cell stack 16 based on the above formula, and in step S12, the requirement value calculation unit 80 calculates the second fuel gas requirement value based on the estimated value.

[0075] According to the present embodiment, the first supply amount V1 is estimated based on the pressure change, the capacity of the oxidant gas supply flow path 24, and the oxidant gas required value Va. Thus, even when the pressure of the oxidant gas in the oxidant gas supply flow path 24 increases, the flow rate of the oxidant gas supplied to the fuel cell stack 16 can be accurately estimated.

[0076] Regarding the above disclosure, the following supplementary notes are further disclosed.

[0077] (Note 1)

[0078] A control device 10 of a fuel cell system 12, the fuel cell system comprising: a fuel cell 16 that generates electricity using a fuel gas and an oxidant gas; an oxidant gas supply flow path 24 that supplies the oxidant gas to the fuel cell; and an oxidant gas supply assembly 14 that supplies the oxidant to the oxidant gas supply flow path gas, wherein the control device of the fuel cell system comprises: a required value acquisition unit 68 that acquires the oxidant gas flow rate to be supplied to the fuel cell, that is, the oxidant gas required value Va; a pressure acquisition unit 70 that acquires the pressure of the oxidant gas flowing in the oxidant gas supply flow path from a pressure sensor 60; a pressure calculation unit 74 that calculates the pressure change amount of the acquired pressure acquired by the pressure acquisition unit per predetermined time; and a supply amount estimation unit 78 that estimates the supply amount of the oxidant gas supplied to the fuel cell based on the capacity of the oxidant gas supply flow path, the pressure change amount, and the oxidant gas required value. According to such a structure, the flow rate of the oxidant gas supplied from the oxidant gas supply flow path to the fuel cell can be accurately estimated. Furthermore, the amount of pressure change per predetermined time of the acquired pressure acquired by the pressure acquisition unit may be an amount of change between a pressure acquired last time and a pressure acquired even more last time.

[0079] (Note 2)

[0080] Alternatively, the control device for the fuel cell system described in Supplement 1 may include a temperature acquisition unit 72 that acquires the temperature of the oxidant gas flowing through the oxidant gas supply flow path from a temperature sensor 62, and the supply amount estimation unit estimates the supply amount of the oxidant gas using the temperature acquired by the temperature acquisition unit. With such a configuration, the supply amount of the oxidant gas supplied to the fuel cell can be estimated with greater accuracy.

[0081] (Note 3)

[0082] Alternatively, in the control device of the fuel cell system described in Appendix 1 or 2, the supply amount estimation unit estimates the supply amount of the oxidant gas when the target power generation of the fuel cell is increased. When the target power generation of the fuel cell is increased, the supply amount of the oxidant gas supplied to the fuel cell is less than the required oxidant gas value as the pressure of the oxidant gas in the oxidant gas supply flow path increases. However, according to the above structure, even when the target power generation of the fuel cell is increased, the supply amount of the oxidant gas supplied to the fuel cell can be accurately estimated.

[0083] (Note 4)

[0084] Alternatively, in the control device of the fuel cell system described in any one of Appendixes 1 to 3, the supply amount estimation unit estimates the supply amount of the oxidant gas when the target power generation of the fuel cell is reduced. When the target power generation of the fuel cell is reduced, the oxidant gas with a relatively high pressure existing in the oxidant gas supply flow path is supplied to the fuel cell, so the supply amount of the oxidant gas supplied to the fuel cell is greater than the required value of the oxidant gas. However, according to the above structure, even when the target power generation of the fuel cell is reduced, the supply amount of the oxidant gas supplied to the fuel cell can be accurately estimated.

[0085] (Note 5)

[0086] The control device for the fuel cell system according to any one of Appendixes 1 to 4 may include an oxidant gas control unit 81 that drives the oxidant gas supply means based on the oxidant gas required value.

[0087] (Note 6)

[0088] The control device of the fuel cell system described in any one of Appendixes 1 to 5 may include a target current value calculation unit 79 that calculates a target current value of the fuel cell based on an estimated value of the oxidant gas supply amount calculated by the supply amount estimation unit.

[0089] (Note 7)

[0090] Alternatively, the control device of the fuel cell system described in any one of Appendixes 1 to 5 may include: a requirement value calculation unit 80 that calculates the fuel gas flow rate to be supplied to the fuel cell, i.e., the fuel gas requirement value, based on the supply amount estimated by the supply amount estimation unit; and a fuel gas control unit 82 that drives the fuel gas supply assembly 22 for supplying the fuel gas to the fuel cell based on the fuel gas requirement value. According to such a structure, the current of the fuel cell can be limited with good accuracy.

[0091] (Note 8)

[0092] Alternatively, the control device of the fuel cell system described in Note 6 comprises: a requirement value calculation unit, which calculates the fuel gas flow rate to be supplied to the fuel cell, i.e., the fuel gas requirement value, based on the target current value calculated by the target current value calculation unit; and a fuel gas control unit, which drives a fuel gas supply component for supplying the fuel gas to the fuel cell based on the fuel gas requirement value.

[0093] Furthermore, the present invention is not limited to the above-mentioned disclosure, and various structures can be adopted without departing from the gist of the present invention.

Claims

1. A control device for a fuel cell system, the fuel cell system comprising: a fuel cell (16) for generating electricity using a fuel gas and an oxidant gas; an oxidant gas supply flow path (24) for supplying the oxidant gas to the fuel cell; and an oxidant gas supply assembly (14) for supplying the oxidant gas to the oxidant gas supply flow path, wherein the control device (10) of the fuel cell system (12) comprises: a required value acquisition unit (68) for acquiring an oxidant gas required value (Va) which is an oxidant gas flow rate to be supplied to the fuel cell; a pressure acquisition unit (70) for acquiring the pressure of the oxidant gas flowing through the oxidant gas supply flow path from a pressure sensor (60); a pressure calculation unit (74) for calculating a pressure change amount of the pressure acquired by the pressure acquisition unit at each predetermined time; and A supply amount estimation unit (78) estimates the supply amount of the oxidant gas supplied to the fuel cell based on the capacity of the oxidant gas supply flow path, the pressure change amount, and the oxidant gas required value.

2. The control device of the fuel cell system according to claim 1, characterized in that: A temperature acquisition unit (72) is provided, wherein the temperature acquisition unit acquires the temperature of the oxidant gas flowing through the oxidant gas supply flow path from a temperature sensor (62). The supply amount estimation section further estimates the supply amount of the oxidant gas using the temperature acquired by the temperature acquisition section.

3. The control device of the fuel cell system according to claim 1, characterized in that: The supply amount estimation unit estimates the supply amount of the oxidant gas when increasing a target power generation amount of the fuel cell.

4. The control device of the fuel cell system according to claim 1, characterized in that: The supply amount estimation unit estimates the supply amount of the oxidant gas when a target power generation amount of the fuel cell is reduced.

5. The control device of the fuel cell system according to claim 1, characterized in that: An oxidant gas control unit (81) is provided, which drives the oxidant gas supply means based on the oxidant gas requirement value.

6. The control device of the fuel cell system according to any one of claims 1 to 5, characterized in that: A target current value calculation unit (79) is provided for calculating a target current value of the fuel cell based on the estimated value of the oxidant gas supply amount calculated by the supply amount estimation unit.

7. The control device of the fuel cell system according to any one of claims 1 to 5, characterized in that: have: a demand value calculation unit (80) for calculating a fuel gas demand value, which is a fuel gas flow rate to be supplied to the fuel cell, based on the supply amount estimated by the supply amount estimation unit; and A fuel gas control unit (82) drives a fuel gas supply unit (22) for supplying the fuel gas to the fuel cell based on the fuel gas requirement value.

8. The control device of the fuel cell system according to claim 6, characterized in that: have: a demand value calculation unit that calculates a fuel gas demand value, which is a fuel gas flow rate to be supplied to the fuel cell, based on the target current value calculated by the target current value calculation unit; and A fuel gas control unit drives a fuel gas supply unit for supplying the fuel gas to the fuel cell based on the fuel gas requirement value.

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