Fuel gas supply system for a fuel cell and control method for the system

Abstract

The present invention relates to a fuel gas supply system for a fuel cell and a control method for the fuel gas supply system. The fuel gas supply system for the fuel cell includes an injector, an inlet pressure acquisition unit, an exhaust valve, a hydrogen partial pressure acquisition unit, and a control unit. The control unit is configured to stop driving the injector when the hydrogen partial pressure becomes equal to or higher than a first upper limit value while the injector is being driven, and to start driving the injector when the hydrogen partial pressure becomes equal to or lower than a first lower limit value while the injector is stopped. When the inlet pressure becomes equal to or higher than a second upper limit value while the exhaust valve is closed, the control unit opens the exhaust valve, and when the inlet pressure becomes equal to or lower than a second lower limit value while the exhaust valve is open, the control unit closes the exhaust valve.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a fuel gas supply system for a fuel cell and a control method for the fuel gas supply system. Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2020-145181 discloses a fuel cell system including: a fuel cell stack; an ejector that supplies fuel to a fuel gas inlet of the fuel cell stack via a supply path; and a discharge valve that discharges fuel exhaust gas and the like from a fuel gas outlet of the fuel cell stack via a discharge path. In the technology of Japanese Unexamined Patent Application Publication No. 2020-145181, by modeling the entire fuel gas supply system of the fuel cell system, each of a plurality of state quantities is inferred and controlled to a target value. Therefore, the mechanism for controlling each of the plurality of state quantities to the target value is configured to be achieved by a combination of the operations of a plurality of components. For example, in order to control two or more state quantities including hydrogen partial pressure and the pressure at the inlet of the fuel cell stack, the operations of two or more components including the ejector and the discharge valve are controlled.

[0003] In the technology of Japanese Unexamined Patent Application Publication No. 2020-145181, if the characteristics of a part of the fuel gas supply system change, such as a change in the specifications of the ejector or the discharge valve or a change in the piping shape, it is necessary to re-study the model of the entire fuel gas supply system. That is, it is necessary to perform a large-scale operation adaptation again for the control logic of the entire fuel gas supply system. When it is necessary to change the characteristics of a part of the fuel gas supply system, such as when expanding the fuel gas supply system to other uses, a huge amount of development man-hours are required. Summary of the Invention

[0004] The first aspect of this specification relates to a fuel gas supply system for a fuel cell. The fuel gas supply system for the fuel cell includes: an injector configured to be connected to a fuel gas inlet of a fuel cell stack via a supply path and supply fuel gas; an inlet pressure acquisition unit configured to acquire the pressure in the supply path, i.e., the inlet pressure; a discharge valve connected to a fuel gas outlet of the fuel cell stack via a discharge path; a hydrogen partial pressure acquisition unit configured to acquire the hydrogen partial pressure of the fuel exhaust gas in the discharge path; and a control unit. The control unit is configured to determine a first upper limit value and a first lower limit value corresponding to the hydrogen partial pressure based on a requested load for the fuel cell stack, and is configured to stop driving the injector when the hydrogen partial pressure becomes equal to or higher than the first upper limit value while the injector is being driven, and is configured to start driving the injector when the hydrogen partial pressure becomes equal to or lower than the first lower limit value while the injector is stopped. The control unit is configured to determine a second upper limit value and a second lower limit value corresponding to the inlet pressure based on the requested load for the fuel cell stack, and is configured to open the discharge valve when the inlet pressure becomes equal to or higher than the second upper limit value while the discharge valve is closed, and is configured to close the discharge valve when the inlet pressure becomes equal to or lower than the second lower limit value while the discharge valve is open.

[0005] According to the above aspect, in order to control one state quantity, i.e., the hydrogen partial pressure in the discharge path, between a first upper limit value and a first lower limit value, the operation of one component, i.e., the injector, is controlled. In addition, in order to control one state quantity, i.e., the inlet pressure in the supply path, between a second upper limit value and a second lower limit value, the operation of one component, i.e., the discharge valve, is controlled. That is, the control of one state quantity to a target value can be achieved by the operation of one component. Moreover, the control of each state quantity can be made independent of each other. Therefore, even when the characteristics of a part of the fuel gas supply system change (e.g., when the injector is changed), it is only necessary to adapt the operation to only one state quantity related to the changed characteristics. Thus, when changing the characteristics of a part of the fuel gas supply system, the development man-hours can be significantly reduced.

[0006] In the above-described manner, the fuel gas supply system may further include a circulation path configured to connect the discharge path and the supply path. The fuel gas supply system may further include a pump configured to be disposed on the circulation path and send fuel exhaust gas to the supply path. The fuel gas supply system may further include an inlet hydrogen concentration acquisition unit configured to acquire the inlet hydrogen concentration at the inlet of the pump. The fuel gas supply system may further include a flow rate acquisition unit configured to acquire the discharge flow rate of the pump. The control unit may be configured to determine a target flow rate value of hydrogen discharged from the pump based on the requested load for the fuel cell stack, and be configured to calculate a current flow rate value of hydrogen discharged from the pump based on the inlet hydrogen concentration and the discharge flow rate, and be configured to control the pump so that the current flow rate value approaches the target flow rate value. According to this configuration, it is possible to control one state quantity, i.e., the current flow rate value of hydrogen, to approach the target flow rate value by the operation of one component of the pump.

[0007] In the above-described manner, the control unit may feedback-control the rotation speed of the pump to reduce the deviation between the target flow rate value and the current flow rate value. Thereby, it is possible to appropriately perform the control of making the current flow rate value approach the target flow rate value.

[0008] In the above-described manner, the fuel gas supply system may further include a gas-liquid separator configured to be disposed on the discharge path, separate the liquid water included in the fuel exhaust gas, and accumulate it. The control unit may open the discharge valve to discharge the liquid water to the outside when the liquid water accumulated in the gas-liquid separator reaches a specified amount. Thereby, it is possible to discharge the liquid water included in the fuel exhaust gas to the outside.

[0009] In the above-described manner, the fuel gas supply system may include a first machine learning unit having a first learning model, and the first learning model is configured to calculate a first feedback gain for controlling the injector corresponding to the hydrogen partial pressure. The first machine learning unit may update the first learning model using the correlation between the operation amount of the injector and the change amount of the hydrogen partial pressure as teaching data. The control unit may control the injector based on the first feedback gain determined by the first learning model. Thereby, it is possible to appropriately adjust the first feedback gain without cumbersome operations. In the control of the hydrogen partial pressure related to the injector, it is possible to suppress overshoot and improve the response speed.

[0010] In the above-described manner, the fuel gas supply system may include a second machine learning unit having a second learning model, and the second learning model calculates a second feedback gain for controlling the discharge valve corresponding to the inlet pressure. The second machine learning unit may update the second learning model using the correlation between the operation amount of the discharge valve and the change amount of the inlet pressure as teaching data. The control unit may control the discharge valve based on the second feedback gain determined by the second learning model. Thereby, it is possible to appropriately adjust the second feedback gain without cumbersome operations. In the control of the inlet pressure related to the discharge valve, it is possible to suppress overshoot and improve the response speed.

[0011] The second mode of this specification relates to a control method for a fuel gas supply system, which includes: an injector connected to the fuel gas inlet of the fuel cell stack via a supply path and supplying fuel gas; an inlet pressure acquisition unit that acquires the pressure of the supply path, i.e., the inlet pressure; an exhaust valve connected to the fuel gas outlet of the fuel cell stack via an exhaust path; and a hydrogen partial pressure acquisition unit that acquires the hydrogen partial pressure of the fuel exhaust gas in the exhaust path. The control method of the fuel gas supply system includes: determining a first upper limit value and a first lower limit value corresponding to the hydrogen partial pressure based on the requested load for the fuel cell stack; when the hydrogen partial pressure becomes equal to or higher than the first upper limit value in a state where the injector is driven, stopping the drive of the injector; when the hydrogen partial pressure becomes equal to or lower than the first lower limit value in a state where the injector is stopped, starting the drive of the injector; determining a second upper limit value and a second lower limit value corresponding to the inlet pressure based on the requested load for the fuel cell stack; when the inlet pressure becomes equal to or higher than the second upper limit value in a state where the exhaust valve is closed, opening the exhaust valve; and when the inlet pressure becomes equal to or lower than the second lower limit value in a state where the exhaust valve is open, closing the exhaust valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Hereinafter, the features, advantages, technology, and industrial importance of exemplary embodiments of the present invention will be described with reference to the drawings, in which the same reference numerals denote the same components, where:

[0013] Figure 1 is a schematic structural diagram of a fuel cell system.

[0014] Figure 2 is a timing chart showing an example of the operation of the fuel gas supply system. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] Embodiment 1

[0016] Structure of Fuel Cell System 1

[0017] Refer to Figure 1 , and the fuel cell system 1 will be described. The fuel cell system 1 is mounted on a fuel cell vehicle, for example. The fuel cell system 1 includes a fuel cell stack 2, a fuel gas supply system 3, and an air supply system 4.

[0018] The fuel cell stack 2 is a device that generates electricity through the chemical reaction of hydrogen and oxygen. Water is generated by the chemical reaction of hydrogen and oxygen. The fuel cell stack 2 includes a plurality of single cells (not shown). Each single cell includes a fuel electrode and an air electrode, and generates electricity by supplying a fuel gas (hydrogen) to the fuel electrode and air including oxygen to the air electrode. The electricity generated by the fuel cell stack 2 is supplied, for example, to the drive motor of a fuel cell vehicle. Unreacted fuel gas (hereinafter referred to as "fuel exhaust gas") that is not used for power generation in the fuel cell stack 2 is discharged from the fuel cell stack 2. The fuel exhaust gas contains water generated during power generation in a vapor state.

[0019] The fuel gas supply system 3 is a device that supplies fuel gas to the fuel cell stack 2. The fuel gas supply system 3 mainly includes a fuel tank 10, an injector 20, a gas-liquid separator 50, a pump 54, a flow meter 55, and an ECU 100 (abbreviation for Electronic Control Unit).

[0020] The fuel gas (hydrogen in this embodiment) supplied to the fuel cell stack 2 is stored in the fuel tank 10. The upstream end of a first fuel supply passage 12 is connected to the fuel tank 10. The downstream end of the first fuel supply passage 12 is connected to the injector 20. In the first fuel supply passage 12, a main stop valve 14 and a pressure reducing valve 16 are provided in sequence from the upstream side to the downstream side. The main stop valve 14 opens and closes the first fuel supply passage 12. When the main stop valve 14 is opened, fuel gas is supplied from the fuel tank 10 to the fuel cell stack 2. The pressure reducing valve 16 adjusts the pressure of the fuel gas flowing in the first fuel supply passage 12. The pressure reducing valve 16 can reduce the pressure of the fuel gas supplied to the fuel cell stack 2 through the first fuel supply passage 12.

[0021] The injector 20 adjusts the pressure and flow rate of the fuel gas supplied to the fuel cell stack 2. The upstream end of a second fuel supply passage 22 is connected to the injector 20. The downstream end of the second fuel supply passage 22 is connected to the fuel gas inlet 2a of the fuel cell stack 2. The injector 20 is controlled to be in an open / closed state according to a control signal IS input from the ECU 100. The pressure and flow rate of the fuel gas are adjusted by adjusting the opening degree and valve opening time of the injector 20. The injector 20 is, for example, a solenoid valve.

[0022] A pressure sensor 24 is provided in the second fuel supply passage 22. The pressure sensor 24 measures the pressure of the fuel gas in the second fuel supply passage 22, that is, the inlet pressure IP. The measured inlet pressure IP is input to the ECU 100.

[0023] The upstream end of the exhaust passage 42 is connected to the fuel gas outlet 2b of the fuel cell stack 2. The downstream end of the exhaust passage 42 is connected to the gas-liquid separator 50. The fuel exhaust gas is supplied to the gas-liquid separator 50 through the exhaust passage 42. The gas-liquid separator 50 separates and accumulates the water contained in the fuel exhaust gas introduced from the exhaust passage 42 into the gas-liquid separator 50. The water vapor contained in the fuel exhaust gas introduced into the gas-liquid separator 50 is cooled, and condensed water (liquid water) accumulates in the gas-liquid separator 50.

[0024] The upstream end of the exhaust and drain passage 56 is connected to the gas-liquid separator 50. An exhaust and drain valve 58 is provided in the exhaust and drain passage 56. In other words, the exhaust and drain valve 58 is connected to the fuel gas outlet 2b via the exhaust passage 42 and the exhaust and drain passage 56. The downstream end of the exhaust and drain passage 56 opens to the outside. The opening and closing state of the exhaust and drain valve 58 is controlled according to the control signal VS input from the ECU 100. When the exhaust and drain valve 58 opens, the unnecessary gas (mainly nitrogen) and the liquid water in the gas-liquid separator 50 flow to the outside.

[0025] The upstream end of the gas circulation passage 52 is connected to the gas-liquid separator 50, and the downstream end is connected to the second fuel supply passage 22. In other words, the gas circulation passage 52 connects the exhaust passage 42 and the second fuel supply passage 22. A pump 54 and a flowmeter 55 are arranged on the gas circulation passage 52. The pump 54 sends out the fuel exhaust gas in the gas-liquid separator 50 to the second fuel supply passage 22. The fuel exhaust gas sent to the second fuel supply passage 22 is supplied to the fuel cell stack 2 again. The rotation speed of the pump 54 is controlled according to the control signal PS input from the ECU 100. Since the discharge amount per one rotation is known, the discharge flow rate can be controlled by controlling the rotation speed.

[0026] The flowmeter 55 measures the discharge flow rate DR of the pump 54. The measured discharge flow rate DR is input to the ECU 100.

[0027] The ECU 100 (control unit) includes a CPU 101 and memories 102 such as a ROM and a RAM. The ECU 100 determines the load (requested load) requested for the fuel cell stack 2, and controls the operations of various components such as the injector 20, the exhaust and drain valve 58, and the pump 54 to obtain the requested current.

[0028] In addition, the ECU 100 functions as a hydrogen partial pressure acquisition unit and an inlet hydrogen concentration acquisition unit. The hydrogen partial pressure acquisition unit is a part that infers the hydrogen partial pressure HP of the fuel exhaust gas in the exhaust passage 42. The inlet hydrogen concentration acquisition unit is a part that infers the inlet hydrogen concentration HC at the inlet of the pump 54. The inference processing of the hydrogen partial pressure HP and the inlet hydrogen concentration HC can be executed based on various information such as the requested load, the actual power generated by the fuel cell stack 2, the measured values of the inlet pressure IP, the discharge flow rate DR, and the like, for example. By inferring the hydrogen partial pressure HP and the inlet hydrogen concentration HC, physical sensors for measuring these values can be dispensed with. Therefore, cost reduction of the fuel gas supply system 3 can be achieved. In addition, if abnormal values are measured due to the lifespan, failure, etc. of the physical sensors, there is a concern that the necessary requirements described later cannot be ensured, but this problem can be avoided by using the inferred values. The specific method for executing these inference processes is not particularly limited. For example, the methods described in Japanese Patent Application Laid-Open No. 2020-145181 and U.S. Patent Application Publication No. 2020-0251760 can be adopted. The entire contents of Japanese Patent Application Laid-Open No. 2020-145181 and U.S. Patent Application Publication No. 2020-0251760 are incorporated herein by reference.

[0029] The air supply system 4 is a device that supplies air to the fuel cell stack 2. The air supply system 4 includes a compressor 62. The compressor 62 is disposed on the air supply passage 60. The upstream end of the air supply passage 60 is open to the outside. The downstream end of the air supply passage 60 is connected to the fuel cell stack 2. The compressor 62 pressurizes the air introduced into the air supply passage 60 and sends it to the fuel cell stack 2. In addition, the upstream end of an air discharge passage 64 is connected to the fuel cell stack 2. The upstream end of the air discharge passage 64 is open to the outside. The air that is not used for power generation in the fuel cell stack 2 is released to the outside through the air discharge passage 64.

[0030] Outline of control of the fuel gas supply system 3

[0031] In the control method of the fuel gas supply system 3 of the present specification, it is characterized in that a plurality of "single input-single output structures" in which the control of one state quantity is achieved by the operation amount of one system component are provided independently of each other. Moreover, in the technology of the present specification, in order to determine the state quantity controlled by the single input-single output structure, three necessary requirements that should be satisfied in the fuel gas supply system 3 are determined. Moreover, three state quantities and three operation quantities are determined using the three necessary requirements. Thereby, the fuel gas supply system 3 can be controlled using three single input-single output structures. Hereinafter, a specific description will be given.

[0032] The first requirement is to supply the amount of hydrogen necessary to avoid deterioration of the fuel cell stack 2. To this end, it is necessary to control the state quantity of the hydrogen partial pressure HP in the exhaust passage 42 to be not lower than the lower limit value. Moreover, the opening / closing state of the injector 20 is used as the operation quantity for controlling the hydrogen partial pressure HP. The exhaust passage 42 is the point where the hydrogen partial pressure is the lowest in the fuel gas supply passage. By maintaining the hydrogen partial pressure HP at this point above the lower limit value, deterioration of the fuel cell stack 2 can be prevented.

[0033] The second requirement is that the pressure of the fuel gas supply system 3 does not exceed the hydrogen-based control upper limit pressure. To this end, it is necessary to control the state quantity of the inlet pressure IP of the fuel gas in the second fuel supply passage 22 to be not more than the upper limit value. Moreover, the opening / closing state of the exhaust and drain valve 58 is used as the operation quantity for controlling the inlet pressure IP.

[0034] The third requirement is to supply hydrogen to the inside of the battery stack by equalizing the hydrogen distribution deviation in the battery stack lamination direction. To this end, it is necessary to control the state quantity of the current hydrogen flow rate value CF to the target flow rate value TF. Moreover, the rotation speed RT of the pump 54 is used as the operation quantity for controlling the current hydrogen flow rate value CF.

[0035] Operation example of the fuel gas supply system 3

[0036] Reference Figure 2 The timing chart of is used to explain the operation example of the fuel gas supply system 3 controlled by the ECU 100. In Figure 2 , during the first period P1 until time t1, it is in the normal load state. During the second period P2 from time t1 to t2, for example, due to an increase in the accelerator opening operated by the user, it is in the high load state. During the third period P3 after time t2, it returns to the normal load state.

[0037] First, the control of the hydrogen partial pressure HP related to the injector 20 will be explained. The ECU 100 determines the current requested load for the fuel cell stack 2 and determines the target hydrogen partial pressure corresponding to the current requested load as the requested hydrogen partial pressure. The requested hydrogen partial pressure is the requested value of the hydrogen partial pressure in the exhaust passage 42. Next, the ECU 100 calculates the first lower limit value LL1 and the first upper limit value UL1 of the hydrogen partial pressure based on the requested hydrogen partial pressure. Since deterioration will occur in the fuel cell stack 2 if the hydrogen partial pressure HP is lower than the first lower limit value LL1, the first lower limit value LL1 is a requirement that must be met. The first upper limit value UL1 is a value obtained by adding a specified margin amount to the first lower limit value LL1.

[0038] Further, the ECU 100 functions as the hydrogen partial pressure acquisition unit described above to infer the hydrogen partial pressure HP. Further, feedback control is performed so that the inferred hydrogen partial pressure HP falls within the range of the first upper limit value UL1 and the first lower limit value LL1. A specific description will be given. During the first period P1, when the hydrogen partial pressure HP becomes equal to or higher than the first upper limit value UL1 in a state where the injector 20 is driven (i.e., an open state), the ECU 100 stops the driving of the injector 20 (i.e., becomes a closed state) (see arrow A1). As a result, the amount of hydrogen supplied to the fuel cell stack 2 decreases, and the hydrogen partial pressure HP decreases. Further, in a state where the injector 20 is stopped (i.e., a closed state), when the hydrogen partial pressure HP becomes equal to or lower than the first lower limit value LL1, the driving of the injector 20 is started (i.e., becomes an open state) (see arrow A2). As a result, the amount of hydrogen supplied to the fuel cell stack 2 increases, and the hydrogen partial pressure HP increases.

[0039] If the high load state is entered at time t1, the first lower limit value LL1 and the first upper limit value UL1 increase. Therefore, the ECU 100 maintains the injector 20 in the open state until the hydrogen partial pressure HP increases and reaches the first upper limit value UL1 (see region R1). If the normal load state is entered at time t2, the first lower limit value LL1 and the first upper limit value UL1 decrease. Therefore, the ECU 100 maintains the injector 20 in the closed state until the hydrogen partial pressure HP decreases and reaches the first lower limit value LL1 (see region R2).

[0040] Second, the control of the inlet pressure IP related to the exhaust drain valve 58 will be described. The ECU 100 calculates the second lower limit value LL2 and the second upper limit value UL2 of the inlet pressure IP based on the requested load for the fuel cell stack 2. Since there is a possibility of a failure if the inlet pressure IP exceeds the second upper limit value UL2, the second upper limit value UL2 is a requirement that must be met. The second lower limit value LL2 is a value obtained by subtracting a specified margin from the second upper limit value UL2. Here, if the margin is large, the deviation from the target value becomes large, and if the margin is small, the opening and closing frequency of the exhaust drain valve 58 increases, and the component durability deteriorates. Therefore, it is only necessary to appropriately determine the margin in such a way as to achieve a balance between the deviation amount from the target value and the opening and closing frequency.

[0041] Moreover, the ECU 100 performs feedback control so that the inlet pressure IP falls within the range of the second upper limit value UL2 and the second lower limit value LL2. Specifically, it will be described. During the first period P1, when the inlet pressure IP becomes equal to or higher than the second upper limit value UL2 with the exhaust and drain valve 58 closed, the ECU 100 opens the exhaust and drain valve 58 (refer to arrow A3). Thereby, the inlet pressure IP decreases. In addition, when the inlet pressure IP becomes equal to or lower than the second lower limit value LL2 with the exhaust and drain valve 58 open, the exhaust and drain valve 58 is closed (refer to arrow A4). Thereby, the inlet pressure IP increases.

[0042] If it shifts to the high load state at time t1, the second lower limit value LL2 and the second upper limit value UL2 increase. Therefore, the ECU 100 maintains the exhaust and drain valve 58 in the closed state until the inlet pressure IP rises and reaches the second upper limit value UL2 (refer to region R3). If it shifts to the normal load state at time t2, the second lower limit value LL2 and the second upper limit value UL2 decrease. Therefore, the ECU 100 maintains the exhaust and drain valve 58 in the open state until the inlet pressure IP decreases and reaches the second lower limit value LL2 (refer to region R4).

[0043] Herein, the case where the exhaust and drain valve 58 opens is not limited to the case where the inlet pressure IP becomes equal to or higher than the second upper limit value UL2. For example, the ECU 100 can control to open the exhaust and drain valve 58 to discharge the liquid water to the outside according to the liquid water accumulated in the gas-liquid separator 50 reaching a specified amount.

[0044] Third, the control of the current flow rate value CF of hydrogen related to the pump 54 will be described. The ECU 100 calculates the target flow rate value TF of hydrogen discharged from the pump 54 based on the requested load for the fuel cell stack 2. For example, it can be calculated based on the current value generated by the fuel cell stack 2 and the temperature of the fuel cell stack 2.

[0045] The ECU 100 infers the inlet hydrogen concentration HC by functioning as the above-mentioned inlet hydrogen concentration acquisition unit. In addition, the ECU 100 obtains the measured value of the discharge flow rate DR of the pump 54 from the flow meter 55. Moreover, based on the inlet hydrogen concentration HC and the discharge flow rate DR, the current flow rate value CF of hydrogen discharged from the pump 54 is calculated. The current flow rate value CF of hydrogen is a value representing the hydrogen supply amount per unit time.

[0046] Moreover, the ECU 100 controls the pump 54 so that the current flow rate value CF of hydrogen approaches the target flow rate value TF. Thereby, as Figure 2As shown, it is possible to make the current flow value CF shown by the solid line follow the target flow value TF shown by the dashed line. The control method can be various. For example, feedback control can be performed with the deviation between the target flow value TF and the current flow value CF as the target variable and the rotational speed RT of the pump 54 as the manipulated variable. Feedback control can use various control methods such as PI control, PID control, P control, and I control.

[0047] Effect

[0048] In the existing fuel gas supply system, a "multi-input - multi-output structure" that controls multiple state variables through the operation amounts of multiple system components is used. In this case, if a characteristic change occurs in a part of the fuel gas supply system (e.g., change of drive components such as valves / pumps, change of piping shape, etc.), it is necessary to re-study the model of the entire fuel gas supply system. Therefore, for example, when applying the fuel gas supply system for passenger cars to other uses (e.g., buses, trucks, trams, ships, stationary generators, etc.), it is necessary to manufacture a test machine for the fuel gas supply system and conduct an adaptation evaluation of the entire system. There is a problem that the development man-hours and development period increase and the development cost rises.

[0049] In view of this, in the fuel gas supply system 3 of this specification, three single-input - single-output structures are provided in an independent manner: (1) controlling the hydrogen partial pressure HP through the opening and closing state of the injector 20, (2) controlling the inlet pressure IP through the opening and closing state of the exhaust drain valve 58, and (3) controlling the current flow value CF of hydrogen through the rotational speed RT of the pump 54. Thus, even when a characteristic of a part of the fuel gas supply system is changed, it is only necessary to perform action adaptation for only one state variable related to the changed characteristic. For example, when the injector 20 is changed, it is only necessary to perform action adaptation of the injector 20 so that the hydrogen partial pressure HP falls within the range of the first upper limit value UL1 and the first lower limit value LL1. In this case, no action adaptation is required for the exhaust drain valve 58 used in the control of the inlet pressure IP. According to the above description, when the fuel gas supply system 3 is extended to other uses, the development man-hours can be significantly suppressed.

[0050] Example 2

[0051] In Example 2, a method in which the fuel gas supply system 3 of Example 1 further includes the first and second machine learning units will be described. The same reference numerals are assigned to the same parts as those in the fuel gas supply system 3 of Example 1, and thus the description is omitted.

[0052] The first program, the second program, the first learning model, and the second learning model are stored in the memory 102. The first program and the second program cause the CPU 101 to function as the first and second machine learning units when executed by the CPU 101.

[0053] The first learning model is a model for calculating the first feedback gain for controlling the injector 20 corresponding to the hydrogen partial pressure HP. The first machine learning unit updates the first learning model using the correlation between the operation amount of the injector 20 and the change amount of the hydrogen partial pressure HP as teaching data. Further, the ECU 100 controls the injector 20 based on the first feedback gain determined by the first learning model. For example, the larger the first feedback gain, the larger the opening degree of the injector 20 is increased. Thereby, the first feedback gain can be appropriately adjusted without cumbersome work. In the control of the hydrogen partial pressure HP related to the injector 20, overshoot suppression and response speed improvement can be achieved.

[0054] The second learning model is a model for calculating the second feedback gain for controlling the exhaust and drain valve 58 corresponding to the inlet pressure IP. The second machine learning unit updates the second learning model using the correlation between the operation amount of the exhaust and drain valve 58 and the change amount of the inlet pressure IP as teaching data. Further, the ECU 100 controls the exhaust and drain valve 58 based on the second feedback gain determined by the second learning model. For example, the larger the second feedback gain, the larger the opening degree of the exhaust and drain valve 58 is increased. Thereby, the second feedback gain can be appropriately adjusted without cumbersome work. In the control of the inlet pressure IP related to the exhaust and drain valve 58, overshoot suppression and response speed improvement can be achieved.

[0055] As described above, specific examples of the present invention have been described in detail, but these are merely examples and do not limit the scope of the technical solution. The technology described in the scope of the technical solution includes technical solutions obtained by various modifications and changes to the specific examples illustrated above.

[0056] The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the technical solution at the time of application. In addition, the technology illustrated in this specification or the drawings can achieve multiple purposes simultaneously, and achieving one of the purposes itself has technical usefulness.

[0057] Modification example

[0058] The control of the injector 20, the exhaust and drain valve 58, and the pump 54 is not limited to feedback control, and various control methods can be used. For example, various control methods such as feedforward control and model predictive control (MPC) can be used, or multiple control methods can be combined.

[0059] The hydrogen partial pressure HP and the inlet hydrogen concentration HC are not limited to the inferred values, and may also be the measured values obtained by the sensors. Additionally, the inlet hydrogen concentration HC may also be a value calculated based on the hydrogen partial pressure HP. Further, the discharge flow rate DR is not limited to the measured value of the flowmeter 55. For example, it may also be a value inferred based on the volume and rotational speed of the pump 54.

[0060] The pressure sensor 24 is an example of an inlet pressure acquisition unit. The exhaust passage 42 and the exhaust and drain passage 56 are examples of discharge passages. The exhaust and drain valve 58 is an example of a discharge valve. The flowmeter 55 is an example of a flow rate acquisition unit.

Claims

1. A fuel gas supply system for a fuel cell, characterized in that, Comprising: An injector configured to be connected to a fuel gas inlet of a fuel cell stack via a supply path and supply fuel gas; An inlet pressure acquisition unit configured to acquire the pressure of the supply path, i.e., the inlet pressure; An exhaust valve connected to a fuel gas outlet of the fuel cell stack via an exhaust path; A hydrogen partial pressure acquisition unit configured to acquire the hydrogen partial pressure of the fuel exhaust gas in the exhaust path; and A control unit wherein the control unit is configured to determine a first upper limit value and a first lower limit value corresponding to the hydrogen partial pressure based on a requested load for the fuel cell stack, and is configured to stop driving the injector when the hydrogen partial pressure becomes equal to or higher than the first upper limit value while the injector is being driven, and is configured to start driving the injector when the hydrogen partial pressure becomes equal to or lower than the first lower limit value while the injector is stopped, the control unit is configured to determine a second upper limit value and a second lower limit value corresponding to the inlet pressure based on a requested load for the fuel cell stack, and is configured to open the exhaust valve when the inlet pressure becomes equal to or higher than the second upper limit value while the exhaust valve is closed, and is configured to close the exhaust valve when the inlet pressure becomes equal to or lower than the second lower limit value while the exhaust valve is open.

2. The fuel gas supply system according to claim 1, wherein Further comprising: A circulation path configured to connect the exhaust path and the supply path; A pump configured to be disposed on the circulation path and send the fuel exhaust gas to the supply path; An inlet hydrogen concentration acquisition unit configured to acquire the inlet hydrogen concentration at the inlet of the pump; and A flow rate acquisition unit configured to acquire the discharge flow rate of the pump, wherein the control unit is configured to determine a target flow rate value of hydrogen discharged from the pump based on a requested load for the fuel cell stack, and is configured to calculate a current flow rate value of hydrogen discharged from the pump based on the inlet hydrogen concentration and the discharge flow rate, and is configured to control the pump so that the current flow rate value approaches the target flow rate value.

3. The fuel gas supply system according to claim 2, characterized in that the control unit is configured to perform feedback control on the rotational speed of the pump to reduce the deviation between the target flow rate value and the current flow rate value.

4. The fuel gas supply system according to any one of claims 1 to 3, characterized in that further comprising a gas-liquid separator configured to be disposed on the exhaust path to separate and accumulate the liquid water included in the fuel exhaust gas, wherein the control unit is configured to open the exhaust valve to discharge the liquid water to the outside when the liquid water accumulated in the gas-liquid separator reaches a specified amount.

5. The fuel gas supply system according to any one of claims 1 to 3, characterized in that further comprising a first machine learning unit having a first learning model configured to calculate a first feedback gain for controlling the injector corresponding to the hydrogen partial pressure, wherein the first machine learning unit is configured to update the first learning model using the correlation between the operation amount of the injector and the change amount of the hydrogen partial pressure as teaching data. The control unit is configured to control the injector based on the first feedback gain determined by the first learning model.

6. The fuel gas supply system according to any one of claims 1 to 3, characterized in that it further includes a second machine learning unit having a second learning model, and the second learning model is configured to calculate a second feedback gain for controlling the discharge valve corresponding to the inlet pressure, wherein the second machine learning unit is configured to update the second learning model using the correlation between the operation amount of the discharge valve and the change amount of the inlet pressure as teaching data, and the control unit is configured to control the discharge valve based on the second feedback gain determined by the second learning model.

7. A control method for a fuel gas supply system, the fuel gas supply system comprising: an injector connected to the fuel gas inlet of the fuel cell stack via a supply path and supplying fuel gas; an inlet pressure acquisition unit that acquires the pressure in the supply path, that is, the inlet pressure; A discharge valve, which is connected to a fuel gas outlet of the fuel cell stack via a discharge path; and a hydrogen partial pressure acquisition unit that acquires the hydrogen partial pressure of the fuel exhaust gas in the discharge path, the control method for the fuel gas supply system being characterized by including: determining a first upper limit value and a first lower limit value corresponding to the hydrogen partial pressure based on the requested load for the fuel cell stack; when the hydrogen partial pressure becomes equal to or higher than the first upper limit value while the injector is in a driving state, stopping the driving of the injector; when the hydrogen partial pressure becomes equal to or lower than the first lower limit value while the injector is in a stopped state, starting the driving of the injector; determining a second upper limit value and a second lower limit value corresponding to the inlet pressure based on the requested load for the fuel cell stack; when the inlet pressure becomes equal to or higher than the second upper limit value while the discharge valve is in a closed state, opening the discharge valve; and when the inlet pressure becomes equal to or lower than the second lower limit value while the discharge valve is in an open state, closing the discharge valve.

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