Control device, fuel cell system, control method therefor, and computer program product

Abstract

The invention relates to a control device, a fuel cell system and a control method thereof, and a computer program product. A control device (10) is capable of performing: a start-up step for starting a fuel cell by supplying a fuel gas to the fuel cell and controlling a valve (52) to supply an oxidant gas at a first flow rate (Q1) to the fuel cell; a warm-up preparation step in which, after the start-up step, the valve is controlled to set the oxidant gas flow rate to a second flow rate (Q2) that is smaller than the first flow rate (Q1), thereby preparing for warm-up of the fuel cell; and a preheating step in which, after the preheating preparation step, the fuel cell is preheated in a state in which the oxidant gas at a third flow rate (Q3), which is larger than the second flow rate, is supplied to the fuel cell.

Description

Technical Field

[0001] The present invention relates to a control device, a fuel cell system, and a control method and program thereof. Background Art

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

[0003] For example, Patent Document 1 discloses preheating the fuel cell stack when the temperature of the fuel cell stack is below freezing. Patent Document 1 also states that in a low temperature environment, the charge capacity of the battery tends to decrease, so the battery becomes overcharged and easily deteriorates.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2021-190305 Summary of the invention

[0007] Problems to be solved by the invention

[0008] A better control device, a fuel cell system, and a control method and program thereof are desired.

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

[0010] Solutions for solving problems

[0011] A first aspect of the present invention relates to a control device, which controls a fuel cell system, wherein the fuel cell system comprises: a fuel cell, which generates electricity by an electrochemical reaction between a fuel gas and an oxidant gas; and a battery, which can be charged with the electricity generated by the fuel cell. In the control device, there is a control unit, which controls a valve, and the valve is used to adjust the flow rate of the oxidant gas supplied to the fuel cell, that is, the oxidant gas flow rate. The control unit can perform the following steps: a starting step, supplying the fuel gas to the fuel cell and controlling the valve to supply the oxidant gas at a first flow rate to the fuel cell, thereby starting the fuel cell; a preheating preparation step, after the starting step, controlling the valve to set the oxidant gas flow rate to a second flow rate that is smaller than the first flow rate, thereby preparing the fuel cell for preheating; and a preheating step, after the preheating preparation step, preheating the fuel cell in a state where the oxidant gas at a third flow rate that is larger than the second flow rate is supplied to the fuel cell.

[0012] A second aspect of the present invention relates to a fuel cell system including the above-mentioned control device.

[0013] A third aspect of the present invention relates to a control method for a fuel cell system, the fuel cell system comprising: a fuel cell that generates electricity through an electrochemical reaction between a fuel gas and an oxidant gas; a battery that can be charged with electricity generated by the fuel cell; and a control unit that controls a valve, the valve being used to adjust the flow rate of the oxidant gas supplied to the fuel cell, i.e., the oxidant gas flow rate. The control method for the fuel cell system comprises: a starting step, in which the fuel gas is supplied to the fuel cell and the control unit controls the valve to supply a first flow rate of the oxidant gas to the fuel cell, thereby starting the fuel cell; a preheating preparation step, in which, after the starting step, the valve is controlled to set the oxidant gas flow rate to a second flow rate that is smaller than the first flow rate, thereby preparing the fuel cell for preheating; and a preheating step, in which, after the preheating preparation step, the fuel cell is preheated while the oxidant gas is supplied to the fuel cell at a third flow rate that is larger than the second flow rate.

[0014] A fourth aspect of the present invention relates to a program for causing a computer to execute the above-mentioned fuel cell system control method.

[0015] Effects of the Invention

[0016] According to the present invention, a better control device, a fuel cell system, and a control method and program thereof can be obtained.

[0017] The above-mentioned objects, features and advantages will be easily understood from the following description of the embodiments described with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram showing the structure of a fuel cell system according to one embodiment of the present invention.

[0019] Figure 2 This is a flowchart for explaining an example of a control method of a fuel cell system.

[0020] Figure 3 This is a timing chart for explaining an example of a control method of a fuel cell system. DETAILED DESCRIPTION

[0021] When preheating the fuel cell stack in the fuel cell system, after the startup process of the fuel cell stack is completed, a preheating preparation step is performed to reduce the output voltage of the fuel cell stack to a predetermined preheating voltage. In the preheating preparation step, the fuel cell stack generates electricity, so the electricity generated by the fuel cell stack is charged to the battery. However, when the battery has sufficient remaining power, when the electricity generated by the fuel cell stack is charged to the battery in the preheating preparation step, the battery may become overcharged. In particular, in a low temperature environment, the charging capacity of the battery tends to decrease, so when the electricity generated by the fuel cell stack is charged to the battery in the preheating preparation step, the battery is prone to become overcharged. The purpose of the present disclosure is to effectively suppress the battery from becoming overcharged when preheating the fuel cell stack.

[0022] A control device 10 , a fuel cell system 12 , a control method of the fuel cell system 12 , and a program 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. The fuel cell system 12 is mounted on a fuel cell vehicle (not shown) such as a fuel cell electric vehicle, for example. Alternatively, the fuel cell system 12 may be mounted on a device other than a vehicle.

[0023] like Figure 1 As shown, the fuel cell system 12 according to the present embodiment includes a fuel cell stack (fuel cell) 14 , a cathode system device 16 , an anode system device 18 , a power supply system 19 , and a control device 10 .

[0024] The fuel cell stack 14 generates electricity through an electrochemical reaction between a fuel gas and an oxidant gas. The fuel gas is, for example, hydrogen. The fuel gas is not particularly limited as long as it is a gas containing hydrogen. The oxidant gas is, for example, air. The oxidant gas is not limited to air as long as it is a gas containing oxygen. The fuel cell stack 14 is formed by stacking a plurality of power generation cells 20. Each power generation cell 20 has: a membrane electrode assembly (MEA: Membrane Electrode Assembly) 22; and a pair of separators 24a, 24b that clamp the membrane electrode assembly 22.

[0025] The membrane electrode structure 22 includes an electrolyte membrane 26, a cathode electrode 28, and an anode electrode 30. The electrolyte membrane 26 is sandwiched between the cathode electrode 28 and the anode electrode 30. The electrolyte membrane 26 is, for example, a solid polymer electrolyte membrane. The solid polymer electrolyte membrane is, for example, a thin film of perfluorosulfonic acid containing water. Although detailed illustration is omitted, the cathode electrode 28 and the anode electrode 30 each include: an electrode catalyst layer bonded to the electrolyte membrane 26; and a gas diffusion layer stacked on the electrode catalyst layer.

[0026] An oxidant gas flow path 32 is formed on the surface of the separator 24a on one side facing the membrane electrode structure 22. The oxidant gas flow path 32 is connected to the oxidant gas inlet 34 and the oxidant gas outlet 36 of the fuel cell stack 14. A fuel gas flow path 38 is formed on the surface of the separator 24b on the other side facing the membrane electrode structure 22. The fuel gas flow path 38 is connected to the fuel gas inlet 40 and the fuel gas outlet 42 of the fuel cell stack 14. The fuel cell stack 14 may also have structural elements other than the above-mentioned structural elements, but the description is omitted here.

[0027] The cathode device 16 includes an oxidant gas supply unit 44, an oxidant gas supply passage 46, an oxidant gas exhaust passage 48, a bypass passage 50, and a valve 52. The cathode device 16 may include components other than these components, but description thereof is omitted here.

[0028] The oxidant gas supply assembly 44 supplies oxidant gas to the oxidant gas supply passage 46. As the oxidant gas supply assembly 44, for example, an air pump or an air compressor can be cited. The oxidant gas supply passage 46 is connected to the oxidant gas inlet portion 34 of the fuel cell stack 14. The oxidant gas supply passage 46 supplies the oxidant gas to the fuel cell stack 14.

[0029] The oxidant gas exhaust passage 48 is connected to the oxidant gas outlet portion 36 of the fuel cell stack 14. The oxidant exhaust gas exhausted from the fuel cell stack 14 flows through the oxidant gas exhaust passage 48. The oxidant gas exhaust passage 48 exhausts the oxidant exhaust gas to the outside of the fuel cell system 12.

[0030] The bypass flow path 50 connects the oxidant gas supply flow path 46 and the oxidant gas exhaust flow path 48. The valve 52 is an on-off valve capable of adjusting the opening degree. The valve 52 adjusts the flow rate of the oxidant gas supplied to the fuel cell stack 14. The valve 52 includes a supply valve 54, an exhaust valve 56, and a bypass valve 58.

[0031] The supply valve 54 is provided in the oxidant gas supply flow path 46. The supply valve 54 opens and closes the oxidant gas supply flow path 46. The supply valve 54 is configured to be able to adjust the opening. As the supply valve 54, for example, a butterfly valve can be cited, but it is not limited thereto. The oxidant gas supply flow path 46 includes: an upstream supply flow path 46a which is a portion on the upstream side compared to the supply valve 54; and a downstream supply flow path 46b which is a portion on the downstream side compared to the supply valve 54. The upstream supply flow path 46a connects the oxidant gas supply assembly 44 and the supply valve 54. The downstream supply flow path 46b connects the supply valve 54 to the oxidant gas inlet portion 34.

[0032] The discharge valve 56 is provided in the oxidant gas discharge flow path 48. The discharge valve 56 opens and closes the oxidant gas discharge flow path 48. The discharge valve 56 is configured to be able to adjust the opening. As the discharge valve 56, for example, a butterfly valve can be cited, but it is not limited thereto. The oxidant gas discharge flow path 48 includes: an upstream discharge flow path 48a which is a portion on the upstream side compared to the discharge valve 56; and a downstream discharge flow path 48b which is a portion on the downstream side compared to the discharge valve 56. The upstream discharge flow path 48a connects the oxidant gas outlet portion 36 to the discharge valve 56. The downstream discharge flow path 48b is connected to the discharge valve 56.

[0033] One end of the bypass flow path 50 is connected to the upstream supply flow path 46a. The other end of the bypass flow path 50 is connected to the downstream discharge flow path 48b. The bypass valve 58 is provided in the bypass flow path 50. The bypass valve 58 opens and closes the bypass flow path 50. The bypass valve 58 is configured to be able to adjust the opening degree. As the bypass valve 58, for example, a butterfly valve can be cited, but it is not limited to this.

[0034] The anode system device 18 includes a fuel gas supply assembly 60, a fuel gas supply flow path 62, a fuel gas discharge flow path 64, a gas-liquid separator 66, a circulation flow path 68, a drain flow path 70, and a drain valve 72. The anode system device 18 may also include components other than these components, but description thereof is omitted here.

[0035] The fuel gas supply assembly 60 supplies fuel gas to the fuel gas supply passage 62. The fuel gas supply assembly 60 includes an injector and an ejector, etc., which are not shown. The fuel gas supply passage 62 connects the fuel gas supply assembly 60 to the fuel gas inlet 40 of the fuel cell stack 14. The fuel gas supply passage 62 supplies fuel gas to the fuel cell stack 14.

[0036] The fuel exhaust gas discharged from the fuel cell stack 14 flows in the fuel gas exhaust flow path 64. The fuel exhaust gas contains generated water due to power generation by the fuel cell stack 14. The gas-liquid separator 66 is provided in the fuel gas exhaust flow path 64. The gas-liquid separator 66 separates the fuel exhaust gas into gas and liquid. The gas-liquid separator 66 can store liquid water separated from the fuel exhaust gas. The circulation flow path 68 guides the fuel exhaust gas flowing through the gas-liquid separator 66 to the ejector (not shown) of the fuel gas supply assembly 60. The fuel exhaust gas flowing in the circulation flow path 68 flows into the fuel gas supply flow path 62 via the ejector and is thereby reused as fuel gas.

[0037] The drain flow path 70 connects the gas-liquid separator 66 to the downstream discharge flow path 48b. The drain flow path 70 guides the liquid water stored in the gas-liquid separator 66 to the downstream discharge flow path 48b together with the fuel exhaust gas. The fuel exhaust gas flowing through the drain flow path 70 is discharged to the outside of the fuel cell system 12 in a state diluted by the oxidant exhaust gas flowing through the downstream discharge flow path 48b. The drain valve 72 is provided in the drain flow path 70. The drain valve 72 opens and closes the drain flow path 70.

[0038] The fuel cell system 12 includes a cooling system (not shown). The cooling system circulates a cooling medium through the fuel cell stack 14. Examples of the cooling medium include pure water, ethylene glycol, and oil.

[0039] The power supply system 19 includes a battery 74 and a DC / DC converter 76. The battery 74 is charged with the power generated by the fuel cell stack 14. The battery 74 can supply power to an electric load 78. The electric load 78 is not particularly limited, and includes, for example, a drive unit having an inverter and a motor for moving the fuel cell vehicle; an oxidant gas supply unit 44; a fuel gas supply unit 60; and an air conditioning unit. Examples of the types of the battery 74 include lead storage batteries and lithium ion secondary batteries.

[0040] The DC / DC converter 76 can step up the output voltage (generated voltage) of the fuel cell stack 14. Alternatively, the DC / DC converter 76 can step down the output voltage of the fuel cell stack 14.

[0041] The temperature sensor 80 and the voltage sensor 82 are connected to the control device 10. Sensors other than the temperature sensor 80 and the voltage sensor 82 can be connected to the control device 10. The temperature sensor 80 sequentially measures a temperature corresponding to the temperature of the fuel cell stack 14. Specifically, the temperature sensor 80 sequentially measures, for example, the temperature of the cooling medium flowing in the fuel cell stack 14. The voltage sensor 82 sequentially measures the output voltage of the fuel cell stack 14.

[0042] The control device 10 includes a computing unit 84 and a storage unit 86. The computing unit 84 is composed of a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). In other words, the computing unit 84 is composed of a processing circuit.

[0043] The calculation unit 84 includes a control unit 88, an acquisition unit 90, and a determination unit 92. The control unit 88, the acquisition unit 90, and the determination unit 92 can be realized by the calculation unit 84 executing a program stored in the storage unit 86.

[0044] Furthermore, at least a part of the control unit 88, the acquisition unit 90, and the determination unit 92 may be implemented by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). In addition, at least a part of the control unit 88, the acquisition unit 90, and the determination unit 92 may be formed by a circuit including discrete devices.

[0045] The storage unit 86 is composed of a volatile memory (not shown) and a non-volatile memory (not shown). Examples of the volatile memory include RAM (Random Access Memory). The volatile memory is used as a working memory of the processor to temporarily store data required for processing or calculation. Examples of the non-volatile memory include ROM (Read Only Memory) and flash memory. The non-volatile memory is used as a storage memory to store programs, forms, mapping tables, etc. The processor, integrated circuit, etc. as described above may include at least a portion of the storage unit 86.

[0046] The control unit 88 is responsible for overall control of the fuel cell system 12. The control unit 88 controls the fuel gas supply assembly 60 and the oxidant gas supply assembly 44. The control unit 88 controls the supply valve 54, the exhaust valve 56, and the bypass valve 58. The control unit 88 controls the DC / DC converter 76. The acquisition unit 90 can grasp the temperature of the fuel cell stack 14 based on the signal supplied from the temperature sensor 80. The acquisition unit 90 can grasp the output voltage of the fuel cell stack 14 based on the signal supplied from the voltage sensor 82.

[0047] Next, an example of a control method of the fuel cell system 12 according to the present embodiment will be described. Figure 2 It is a flowchart for explaining the control method of the fuel cell system 12 .

[0048] exist Figure 2In the initial state, the fuel cell stack 14 stops operating. When oxygen remains in the oxidant gas flow path 32 of the power generation cell 20 when the fuel cell stack 14 is stopped, it sometimes causes the electrode catalyst layer to deteriorate. Therefore, when the fuel cell stack 14 is stopped, fuel gas is supplied to the oxidant gas flow path 32. As a result, the oxygen remaining in the oxidant gas flow path 32 reacts with the hydrogen in the fuel gas, so the oxygen concentration of the oxidant gas flow path 32 decreases. That is, at the time of starting the fuel cell stack 14, the oxygen concentration of the oxidant gas flow path 32 becomes low. When the fuel cell stack 14 is stopped, the supply valve 54 and the exhaust valve 56 are each in a fully closed state to prevent the oxidant gas from flowing into the oxidant gas flow path 32. In addition, the bypass valve 58 is in a fully open state. Furthermore, it is also possible to supply fuel gas to the fuel gas flow path 38 while suppressing the flow of oxidant gas into the oxidant gas flow path 32, thereby performing oxygen consumption control to consume the oxygen remaining in the oxidant gas flow path 32, so as to reduce the oxygen concentration in the oxidant gas flow path 32 at the time of starting the fuel cell stack 14.

[0049] In step S1, the control device 10 receives a startup instruction of the fuel cell stack 14. Specifically, for example, when a user turns on a power switch (not shown), the power switch supplies a startup instruction to the control device 10. The acquisition unit 90 can grasp the startup instruction based on the signal supplied from the power switch. Then, the process proceeds to step S2. That is, the startup steps (steps S2 to S5) are implemented.

[0050] In step S2, the control unit 88 controls the fuel gas supply assembly 60 to supply fuel gas from the fuel gas supply assembly 60 to the fuel gas supply flow path 62. The fuel gas supplied to the fuel gas supply flow path 62 is guided to the fuel gas flow path 38 of the fuel cell stack 14. Thereafter, the process proceeds to step S3.

[0051] In step S3, the control unit 88 controls the oxidant gas supply assembly 44 to deliver the oxidant gas from the oxidant gas supply assembly 44 to the upstream supply flow path 46a. In addition, at this stage, the supply valve 54 is closed, so the oxidant gas has not yet flowed into the fuel cell stack 14. Thereafter, the process moves to step S4. In addition, step S3 may be performed at the same timing as step S2, or may be performed before step S2.

[0052] In step S4, the control unit 88 controls the valve 52 to supply the oxidant gas of the first flow rate Q1 to the fuel cell stack 14. Specifically, the control unit 88 opens the supply valve 54, the exhaust valve 56 and the bypass valve 58. The oxidant gas supplied to the upstream supply flow path 46a from the oxidant gas supply assembly 44 flows to the downstream supply flow path 46b via the supply valve 54 and flows to the bypass flow path 50. The oxidant gas flowing to the downstream supply flow path 46b is guided to the oxidant gas flow path 32 of the fuel cell stack 14. As a result, the fuel gas sealed in the oxidant gas flow path 32 is discharged to the oxidant gas exhaust flow path 48 by the oxidant gas. The fuel gas guided to the oxidant gas exhaust flow path 48 is discharged to the outside of the fuel cell system 12 in a state diluted by the oxidant gas guided from the bypass flow path 50.

[0053] The fuel cell stack 14 generates electricity through an electrochemical reaction between the fuel gas and the oxidant gas. The output voltage of the fuel cell stack 14 is boosted by the DC / DC converter 76. The electricity generated by the fuel cell stack 14 is charged to the battery 74. In addition, the electricity generated by the fuel cell stack 14 can be used to drive the oxidant gas supply assembly 44 and the fuel gas supply assembly 60.

[0054] The fuel cell stack 14 discharges the fuel exhaust from the fuel gas flow path 38 to the fuel gas exhaust flow path 64 and discharges the oxidant exhaust from the oxidant gas flow path 32 to the upstream exhaust flow path 48a. The fuel exhaust contains generated water generated by power generation. The fuel exhaust discharged to the fuel gas exhaust flow path 64 is guided to the gas-liquid separator 66. The gas-liquid separator 66 separates the fuel exhaust into gas and liquid. The fuel exhaust guided from the gas-liquid separator 66 to the circulation flow path 68 is returned to the fuel gas supply assembly 60 and reused. The liquid water separated from the fuel exhaust in the gas-liquid separator 66 is stored in the gas-liquid separator 66.

[0055] The oxidant exhaust gas discharged to the upstream exhaust flow path 48a is guided to the downstream exhaust flow path 48b via the exhaust valve 56. The oxidant exhaust gas guided to the downstream exhaust flow path 48b is discharged to the outside of the fuel cell system 12 in a state mixed with the oxidant gas guided from the bypass flow path 50.

[0056] When the control unit 88 opens the drain valve 72, the liquid water stored in the gas-liquid separator 66 is discharged to the outside of the fuel cell system 12 through the drain flow path 70 and the downstream side discharge flow path 48b together with the fuel exhaust gas. The fuel exhaust gas guided from the drain flow path 70 to the downstream side discharge flow path 48b is discharged to the outside of the fuel cell system 12 in a state diluted by the oxidant gas and the oxidant exhaust gas.

[0057] By adjusting the openings of the supply valve 54, the discharge valve 56, and the bypass valve 58, the flow rate of the oxidant gas supplied to the fuel cell stack 14, i.e., the oxidant gas flow rate, can be set. Hereinafter, the flow rate of the oxidant gas supplied to the fuel cell stack 14 is sometimes referred to as "oxidant gas flow rate". In step S4, the control unit 88 sets the openings of the supply valve 54, the discharge valve 56, and the bypass valve 58 to predetermined openings, thereby supplying the oxidant gas of the first flow rate Q1 to the fuel cell stack 14. After step S4, the process proceeds to step S5.

[0058] In step S5, the determination unit 92 determines whether the startup process of the fuel cell stack 14 is completed. Specifically, the determination unit 92 determines whether the output voltage of the fuel cell stack 14 reaches a predetermined startup voltage V1. The output voltage of the fuel cell stack 14 is acquired by the acquisition unit 90. When the output voltage of the fuel cell stack 14 is lower than the startup voltage V1 (refer to Figure 3 ), the determination unit 92 determines that the startup process of the fuel cell stack 14 is not completed. When the output voltage of the fuel cell stack 14 reaches the startup voltage V1, the determination unit 92 determines that the startup process of the fuel cell stack 14 is completed. Alternatively, the determination unit 92 determines whether the startup process of the fuel cell stack 14 is completed based on the elapsed time after step S4 is performed.

[0059] If the determination unit 92 determines that the startup process of the fuel cell stack 14 is not completed (No in step S5), step S5 is repeated. If the determination unit 92 determines that the startup process of the fuel cell stack 14 is completed (Yes in step S5), the process proceeds to step S6.

[0060] In step S6, the determination unit 92 determines whether preheating of the fuel cell stack 14 is required. Specifically, the determination unit 92 determines, for example, whether the temperature of the fuel cell stack 14 is below a predetermined first temperature threshold. The temperature of the fuel cell stack 14 is acquired by the acquisition unit 90. The first temperature threshold can be set to, for example, the freezing point (0°C). The first temperature threshold can be appropriately set and can be either higher or lower than the freezing point. When the temperature of the fuel cell stack 14 is higher than the first temperature threshold, the determination unit 92 determines that preheating of the fuel cell stack 14 is not required. When the temperature of the fuel cell stack 14 is below the first temperature threshold, the determination unit 92 determines that preheating of the fuel cell stack 14 is required.

[0061] If the determination unit 92 determines that the preheating of the fuel cell stack 14 is not necessary (No in step S6), the process proceeds to step S13. If the determination unit 92 determines that the preheating of the fuel cell stack 14 is necessary (Yes in step S6), the process proceeds to step S7. That is, the preheating preparation step (steps S7 to S10) is performed.

[0062] In step S7, the control unit 88 controls the valve 52 to set the oxidant gas flow rate to a second flow rate Q2 that is smaller than the first flow rate Q1. Specifically, the control unit 88 closes the supply valve 54 to a predetermined supply suppression opening, and closes the exhaust valve 56 to a predetermined exhaust suppression opening. As a result, the oxidant gas flow rate is reduced from the first flow rate Q1 to the second flow rate Q2. As a result, the power generation of the fuel cell stack 14 is reduced. When the power generation of the fuel cell stack 14 is reduced, the output voltage of the fuel cell stack 14 decreases. Thereafter, the process moves to step S8.

[0063] In step S8, the determination unit 92 determines whether the preparation for warming up the fuel cell stack 14 is expected to be completed. Specifically, the determination unit 92 determines whether the output voltage of the fuel cell stack 14 reaches a predetermined voltage threshold value V2 (see Figure 3 ) or less. The voltage threshold value V2 is a voltage higher than the preheating voltage V3. When the output voltage of the fuel cell stack 14 is higher than the voltage threshold value V2, the determination unit 92 determines that the preparation for preheating of the fuel cell stack 14 is not expected to be completed. When the output voltage of the fuel cell stack 14 decreases to the voltage threshold value V2, the determination unit 92 determines that the preparation for preheating of the fuel cell stack 14 is expected to be completed. Alternatively, the determination unit 92 may determine whether the preparation for preheating of the fuel cell stack 14 is expected to be completed based on the elapsed time after the start of step S7.

[0064] If the determination unit 92 determines that the preheating preparation of the fuel cell stack 14 is not expected to be completed (No in step S8), step S8 is repeated. If the determination unit 92 determines that the preheating preparation of the fuel cell stack 14 is expected to be completed (Yes in step S8), the process proceeds to step S9.

[0065] In step S9, the control unit 88 controls the valve 52 to set the oxidant gas flow rate to a third flow rate Q3 that is larger than the second flow rate Q2. Specifically, the control unit 88 opens the supply valve 54 to a predetermined preheating supply opening, and opens the discharge valve 56 to a predetermined preheating discharge opening. Thus, the oxidant gas flow rate can be increased from the second flow rate Q2 to the third flow rate Q3. Then, the process moves to step S10.

[0066] In step S10, the determination unit 92 determines whether the preheating preparation of the fuel cell stack 14 is completed. Specifically, the determination unit 92 determines whether the output voltage of the fuel cell stack 14 has dropped to the preheating voltage V3 (see Figure 3). When the output voltage of the fuel cell stack 14 is higher than the preheating voltage V3, the determination unit 92 determines that the preheating preparation of the fuel cell stack 14 has not been completed. When the output voltage of the fuel cell stack 14 drops to the preheating voltage V3, the determination unit 92 determines that the preheating preparation of the fuel cell stack 14 is completed. Alternatively, the determination unit 92 determines whether the preheating preparation of the fuel cell stack 14 is completed based on the elapsed time after the start of step S9.

[0067] If the determination unit 92 determines that the preheating preparation of the fuel cell stack 14 is not completed (No in step S10), step S10 is repeated. If the determination unit 92 determines that the preheating preparation of the fuel cell stack 14 is completed (Yes in step S10), the process proceeds to step S11. That is, the preheating step (steps S11 and S12) is performed.

[0068] In step S11, the control unit 88 preheats the fuel cell stack 14. Specifically, the control unit 88 controls the valve 52 to maintain the oxidant gas flow rate at the third flow rate Q3, so that the output voltage of the fuel cell stack 14 is maintained at the preheating voltage V3. As a result, the air-fuel ratio of the oxidant gas supplied to the power generation cell 20 can be a predetermined preheating air-fuel ratio. The preheating air-fuel ratio is less than the air-fuel ratio when the fuel cell stack 14 is normally operated. Moreover, the normal operation of the fuel cell stack 14 refers to the operation of the fuel cell stack 14 in a state where the fuel cell stack 14 is not preheated. When the fuel cell stack 14 is normally operating, the air-fuel ratio of the oxidant gas supplied to the power generation cell 20 is made relatively large, thereby reducing the heat loss of the fuel cell stack 14.

[0069] By setting the air-fuel ratio of the oxidant gas supplied to the power generation unit cell 20 to the preheating air-fuel ratio, the fuel cell stack 14 can perform low-efficiency power generation. As a result, the heat generation (heat loss) of the fuel cell stack 14 increases, thereby promoting the preheating of the fuel cell stack 14. After step S11, the process proceeds to step S12.

[0070] In step S12, the determination unit 92 determines whether the preheating of the fuel cell stack 14 is completed. Specifically, the determination unit 92 determines whether the temperature of the fuel cell stack 14 is above a predetermined second temperature threshold. The temperature of the fuel cell stack 14 is acquired by the acquisition unit 90. When the temperature of the fuel cell stack 14 is lower than the second temperature threshold, the determination unit 92 determines that the preheating of the fuel cell stack 14 is not yet completed. When the temperature of the fuel cell stack 14 rises to the second temperature threshold, the determination unit 92 determines that the preheating of the fuel cell stack 14 is completed. Alternatively, the determination unit 92 determines whether the preheating of the fuel cell stack 14 is completed based on the time elapsed after the preheating of step S11 is started.

[0071] If the determination unit 92 determines that the warm-up of the fuel cell stack 14 is not completed (No in step S12), step S12 is repeated. If the determination unit 92 determines that the warm-up of the fuel cell stack 14 is completed (Yes in step S12), the process proceeds to step S13.

[0072] In step S13, the control unit 88 causes the fuel cell stack 14 to perform normal operation. Specifically, the control unit 88 controls the current of the fuel cell stack 14 based on the power required for the fuel cell stack 14. Figure 2 The indicated processing is completed.

[0073] Figure 3 1 is a timing chart for explaining an example of a control method of the fuel cell system 12. Specifically, Figure 3 The timing chart is shown in the case where the fuel cell stack 14 is started up in a state where the temperature of the fuel cell stack 14 is below freezing point.

[0074] like Figure 3 As shown, the control unit 88 sequentially performs the startup step, the preheating preparation step, and the preheating step. In addition, the control unit 88 controls the voltage of the fuel cell stack 14 after the startup step is started until the preheating step is completed, so that the output voltage of the fuel cell stack 14 follows the predetermined voltage command. In addition, the control unit 88 drives the oxidant gas supply assembly 44 and the fuel gas supply assembly 60 after the startup step is started until the preheating step is completed.

[0075] In the startup step, the output voltage of the fuel cell stack 14 is increased to a predetermined startup voltage V1, thereby confirming whether the fuel cell stack 14 can be operated without problems. At time t1, the startup step starts by receiving a startup command of the fuel cell stack 14. At time t1, the control unit 88 controls the oxidant gas supply assembly 44 to supply oxidant gas to the upstream supply flow path 46a. Moreover, in the initial state of the fuel cell stack 14, the bypass valve 58 is fully opened. In addition, at time t1, the control unit 88 controls the fuel gas supply assembly 60 to supply fuel gas to the fuel cell stack 14.

[0076] At time t2, the control unit 88 outputs a full opening command to the supply valve 54 and the exhaust valve 56, respectively, so that the supply valve 54 and the exhaust valve 56 are opened. The control unit 88 opens the supply valve 54, thereby supplying the oxidant gas to the fuel cell stack 14. In addition, the control unit 88 opens the exhaust valve 56, thereby the fuel gas sealed in the oxidant gas flow path 32 of the fuel cell stack 14 is discharged from the fuel cell stack 14. Thus, the operation of the supply valve 54 and the exhaust valve 56 can be confirmed. In addition, even if frozen matter is attached to the valve bodies of the supply valve 54 and the exhaust valve 56 at low temperatures, the frozen matter can be destroyed by the valve opening action.

[0077] When the oxidant gas is supplied to the fuel cell stack 14, the fuel cell stack 14 starts to generate electricity through the electrochemical reaction of the fuel gas and the oxidant gas. When the fuel cell stack 14 starts to generate electricity, the output voltage of the fuel cell stack 14 increases. Figure 3 , a voltage command is shown, but the actual output voltage of the fuel cell stack 14 is not shown.

[0078] The larger the opening of the supply valve 54, the larger the flow rate supplied to the fuel cell stack 14, that is, the oxidant gas flow rate. In this embodiment, at time t3, the output voltage of the fuel cell stack 14 rises to the starting voltage V1. Here, the output voltage of the fuel cell stack 14 is the open circuit voltage (OCV). The oxidant gas flow rate when the output voltage of the fuel cell stack 14 reaches the starting voltage V1 becomes the first flow rate Q1. At time t3, the startup step is completed.

[0079] The warm-up preparation step starts at time t3. In order to warm up the fuel cell stack 14 using low-efficiency power generation, the output voltage of the fuel cell stack 14 needs to be reduced to the warm-up voltage V3. Therefore, in the warm-up preparation step, the output voltage of the fuel cell stack 14 is reduced to the warm-up voltage V3.

[0080] Specifically, in the preheating preparation step, at time t3, the control unit 88 closes the supply valve 54 to the supply suppression opening degree, and closes the discharge valve 56 to the discharge suppression opening degree. As a result, at time t4, the oxidant gas flow rate is reduced to the second flow rate Q2. Figure 3 In the example of , the supply suppression opening and the discharge suppression opening are each set to an opening greater than 0 degrees (the opening in the fully closed state) so that the oxidant gas flow rate is maintained at the second flow rate Q2. Alternatively, the supply suppression opening and the discharge suppression opening may each be set to 0 degrees, for example. In this case, the oxidant gas flow rate becomes 0.

[0081] When the oxidant gas flow rate is reduced to the second flow rate Q2, the fuel cell stack 14 generates electricity while consuming the oxidant gas remaining in the fuel gas flow path 38. Therefore, in the warm-up preparation step, the amount of power generated by the fuel cell stack 14 can be suppressed. As a result, the output voltage of the fuel cell stack 14 can be reduced.

[0082] In the preheating preparation step, the power generated by the fuel cell stack 14 can be supplied to the battery 74. The lower the temperature of the battery 74, the smaller the charging capacity of the battery 74. Therefore, in the preheating preparation step, the battery 74 is easily overcharged. However, in the preheating preparation step, the power generation of the fuel cell stack 14 can be suppressed, so the power supplied to the battery 74 can be reduced. Thus, the overcharging of the battery 74 can be suppressed. In addition, during the preheating preparation step, the control unit 88 drives the oxidant gas supply assembly 44 and the fuel gas supply assembly 60, so the power generated by the fuel cell stack 14 is consumed by the oxidant gas supply assembly 44 and the fuel gas supply assembly 60. Therefore, the overcharging of the battery 74 can be further suppressed. Moreover, in the preheating preparation step, the bypass valve 58 is opened, so that the oxidant gas supplied from the oxidant gas supply assembly 44 to the upstream supply flow path 46a can escape to the downstream discharge flow path 48b via the bypass flow path 50.

[0083] In the warm-up preparation step, the control unit 88 controls the DC / DC converter 76 to reduce the output voltage of the fuel cell stack 14 at a predetermined rate. The battery 74 is easily degraded when rapidly charged at low temperatures. Therefore, the reduction speed (rate) of the output voltage of the fuel cell stack 14 is set to a size that can prevent the battery 74 from degrading.

[0084] At time t5, when the output voltage of the fuel cell stack 14 drops to a predetermined voltage threshold value V2, the control unit 88 opens the supply valve 54 and the exhaust valve 56, thereby increasing the oxidant gas flow rate to the third flow rate Q3. Specifically, the control unit 88 opens the supply valve 54 to a fully opened state and opens the exhaust valve 56 to an opening smaller than the fully opened state. Moreover, the opening degrees of the supply valve 54 and the exhaust valve 56 can be appropriately set. In addition, at time t5, the control unit 88 closes the bypass valve 58 to a predetermined opening degree. As a result, the oxidant gas flow rate increases to the third flow rate Q3.

[0085] Thus, at time t6 , when the output voltage of the fuel cell stack 14 drops to the preheating voltage V3 (when the preheating preparation step ends), it is possible to smoothly transition from the preheating preparation step to the preheating step.

[0086] The preheating step starts at time t6. In the preheating step, the control unit 88 performs feedback control on the opening of the bypass valve 58, thereby maintaining the output voltage of the fuel cell stack 14 at the preheating voltage V3. As a result, the fuel cell stack 14 can be preheated using low-efficiency power generation. In the present embodiment, in the preheating step, the openings of the supply valve 54 and the exhaust valve 56 are each set to a fixed value, but it is also possible to perform feedback control on the openings of the supply valve 54 and the exhaust valve 56, thereby maintaining the output voltage of the fuel cell stack 14 at the preheating voltage V3.

[0087] At time t7, the control unit 88 outputs a command for a voltage greater than the preheating voltage V3 when it is expected that the preheating of the fuel cell stack 14 is completed. This allows a smooth transition from the preheating step to normal operation of the fuel cell stack 14 when the preheating operation is completed at time t8.

[0088] According to the present embodiment, in the preheating preparation step, the control unit 88 controls the valve 52 to set the oxidant gas flow rate to the second flow rate Q2 which is smaller than the first flow rate Q1, thereby suppressing the power generated by the fuel cell stack 14. As a result, in the preheating preparation step, the power charged from the fuel cell stack 14 to the battery 74 can be suppressed, thereby suppressing overcharging of the battery 74. Therefore, a better control device 10, fuel cell system 12, control method of the fuel cell system 12, and program can be obtained.

[0089] The computer program (computer software) according to the present embodiment may also be referred to as a computer program product. The computer program product is not limited to a computer program stored in a storage medium, and includes a computer program transmitted, distributed, or downloaded via the Internet or the like.

[0090] In connection with the above disclosure, the following supplementary notes are also disclosed.

[0091] (Note 1)

[0092] A control device 10 controls a fuel cell system 12, wherein the fuel cell system comprises: a fuel cell (fuel cell stack) 14, which generates electricity by an electrochemical reaction between a fuel gas and an oxidant gas; and a battery 74, which can be charged with the electricity generated by the fuel cell. In the control device, there is a control unit 88, which controls a valve 52, and the valve is used to adjust the flow rate of the oxidant gas supplied to the fuel cell, that is, the oxidant gas flow rate. The control unit can perform the following steps: a starting step, supplying the fuel gas to the fuel cell and controlling the valve to supply the oxidant gas at a first flow rate Q1 to the fuel cell, thereby starting the fuel cell; a preheating preparation step, after the starting step, controlling the valve to set the oxidant gas flow rate to a second flow rate Q2 that is smaller than the first flow rate, thereby preparing the fuel cell for preheating; and a preheating step, after the preheating preparation step, preheating the fuel cell in a state where the oxidant gas at a third flow rate Q3 that is larger than the second flow rate is supplied to the fuel cell.

[0093] According to such a structure, in the preheating preparation step, the control unit controls the valve to set the oxidant gas flow rate to a second flow rate that is smaller than the first flow rate, thereby suppressing the power generated by the fuel cell stack. As a result, in the preheating preparation step, the power charged from the fuel cell stack to the battery can be suppressed, thereby suppressing overcharging of the battery. Therefore, a better control device can be obtained.

[0094] (Note 2)

[0095] In the control device described in Appendix 1, it may be that, in the preheating preparation step, when the output voltage of the fuel cell decreases to a predetermined voltage threshold value V2, the control unit controls the valve to set the oxidant gas flow rate from the second flow rate to the third flow rate.

[0096] According to such a configuration, it is possible to smoothly shift from the preheating preparation step to the preheating step.

[0097] (Note 3)

[0098] In the control device recorded in Note 1 or 2, it may also be that the valve includes a supply valve 54 provided in the oxidant gas supply flow path 46, and the oxidant gas supply flow path is used to supply the oxidant gas to the fuel cell, and in the startup step, the control unit opens the supply valve, and in the preheating preparation step, when the oxidant gas flow rate is set from the first flow rate to the second flow rate, the control unit closes the supply valve to a predetermined supply suppression opening.

[0099] According to such a configuration, in the preheating preparation step, the oxidizing gas flow rate can be made smaller than the first flow rate.

[0100] (Note 4)

[0101] In the control device described in Appendix 3, the valve may include an exhaust valve 56 provided in an oxidant gas exhaust flow path 48, the oxidant exhaust gas discharged from the fuel cell flows through the oxidant gas exhaust flow path, and in the startup step, the control unit opens the exhaust valve.

[0102] According to such a configuration, even when the fuel gas is sealed in the oxidant gas flow path of the fuel cell while the operation of the fuel cell is stopped, the fuel gas existing in the oxidant gas flow path can be discharged smoothly.

[0103] (Note 5)

[0104] In the control device described in Supplementary Note 4, when the oxidizing gas flow rate is set from the first flow rate to the second flow rate in the preheating preparation step, the control unit may close the discharge valve to a predetermined discharge suppression opening degree.

[0105] According to such a configuration, it is possible to suppress the oxidizing gas flow rate from falling below the second flow rate.

[0106] (Note 6)

[0107] In the control device recorded in Note 4 or 5, the valve may also include a bypass valve 58 arranged in a bypass flow path 50, the bypass flow path connects the oxidant gas supply flow path with the oxidant gas exhaust flow path, one end of the bypass flow path is connected to a portion 46a of the oxidant gas supply flow path that is upstream of the supply valve, and the other end of the bypass flow path is connected to a portion 48b of the oxidant gas exhaust flow path that is downstream of the exhaust valve, and in the preheating preparation step, the control unit maintains the bypass valve in an open state.

[0108] According to such a configuration, in the preheating preparation step, the oxidant gas flow rate can be reduced from the first flow rate to the second flow rate while the oxidant gas supply assembly for supplying the oxidant gas to the oxidant gas supply flow path is driven. In this case, the oxidant gas supply assembly can consume the power generated by the fuel cell, thereby further suppressing overcharging of the battery.

[0109] (Note 7)

[0110] A fuel cell system includes the control device according to any one of Supplementary Notes 1 to 6.

[0111] (Note 8)

[0112] 14. The control method of a fuel cell system as claimed in claim 13, wherein the at least one element is a part of a fuel cell and the at least one element is a part of a fuel cell. The at least one element is a part of a fuel cell and the at least one element is a part of a fuel cell. The at least one element is a part of a fuel cell and the at least one element is a part of a fuel cell.

[0113] (Note 9)

[0114] A program causes a computer to execute the control method of the fuel cell system described in Supplementary Note 8.

[0115] Furthermore, the present invention is not limited to the above disclosure, and various structures can be adopted without departing from the gist of the present invention.

Claims

1. A control device for controlling a fuel cell system, wherein the fuel cell system comprises: Fuel cells that generate electricity through an electrochemical reaction between a fuel gas and an oxidant gas; and a storage battery capable of being charged with the electricity generated by the fuel cell, In the control device, A control unit is provided, the control unit controls a valve, the valve is used to adjust the flow rate of the oxidant gas supplied to the fuel cell, that is, the oxidant gas flow rate, The control unit can perform the following steps: a startup step of supplying the fuel gas to the fuel cell and controlling the valve to supply a first flow rate of the oxidant gas to the fuel cell, thereby starting the fuel cell; a preheating preparation step, after the startup step, controlling the valve to set the oxidant gas flow rate to a second flow rate that is smaller than the first flow rate, thereby preparing the fuel cell for preheating; as well as A preheating step, after the preheating preparation step, preheating the fuel cell in a state where a third flow rate of the oxidant gas greater than the second flow rate is supplied to the fuel cell.

2. The control device according to claim 1, characterized in that: In the warm-up preparation step, when the output voltage of the fuel cell decreases to a predetermined voltage threshold, the control unit controls the valve to set the oxidant gas flow rate from the second flow rate to the third flow rate.

3. The control device according to claim 1, characterized in that: The valve includes a supply valve provided in an oxidant gas supply flow path for supplying the oxidant gas to the fuel cell. In the startup step, the control unit opens the supply valve. When the oxidizing gas flow rate is set from the first flow rate to the second flow rate in the preheating preparation step, the control unit closes the supply valve to a predetermined supply suppression opening degree.

4. The control device according to claim 3, characterized in that: The valve includes an exhaust valve provided in an oxidant gas exhaust flow path, and the oxidant exhaust gas exhausted from the fuel cell flows through the oxidant gas exhaust flow path. In the startup step, the control unit opens the discharge valve.

5. The control device according to claim 4, characterized in that: When the oxidizing gas flow rate is set from the first flow rate to the second flow rate in the preheating preparation step, the control unit closes the discharge valve to a predetermined discharge suppression opening degree.

6. The control device according to claim 4, characterized in that: The valve includes a bypass valve provided in a bypass flow path, wherein the bypass flow path connects the oxidant gas supply flow path and the oxidant gas exhaust flow path. One end of the bypass flow path is connected to a portion of the oxidant gas supply flow path that is upstream of the supply valve. The other end of the bypass flow path is connected to a portion of the oxidant gas discharge flow path that is downstream of the discharge valve. In the warm-up preparation step, the control unit maintains the bypass valve in an open state. 7 . A fuel cell system comprising the control device according to claim 1 .

8. A control method for a fuel cell system, the fuel cell system comprising: Fuel cells generate electricity through the electrochemical reaction of a fuel gas and an oxidant gas; a storage battery capable of being charged with the electricity generated by the fuel cell; and a control unit that controls a valve for adjusting a flow rate of the oxidant gas supplied to the fuel cell, that is, an oxidant gas flow rate, The control method of the fuel cell system comprises: a startup step of supplying the fuel gas to the fuel cell and the control unit controlling the valve to supply the oxidant gas at a first flow rate to the fuel cell, thereby starting the fuel cell; a preheating preparation step, after the startup step, controlling the valve to set the oxidant gas flow rate to a second flow rate that is smaller than the first flow rate, thereby preparing the fuel cell for preheating; as well as A preheating step, after the preheating preparation step, preheating the fuel cell in a state where a third flow rate of the oxidant gas greater than the second flow rate is supplied to the fuel cell.

9. A computer program product for causing a computer to execute the control method of the fuel cell system according to claim 8.

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