Power generation control system for fuel cell

Abstract

Provided is a fuel cell power generation control system capable of efficiently determining a target power generation amount for each of a plurality of fuel cell systems with a small calculation load when an output limit occurs in any of the plurality of fuel cell systems. A fuel cell power generation control system (1) is provided with: a plurality of fuel cell systems (4) each provided with a fuel cell (41) capable of generating power by a reaction between a fuel gas and an oxidant gas; a required power generation amount acquisition unit (21) that acquires a required power generation amount for the plurality of fuel cell systems (4); a limit value acquisition unit (22) that acquires an output limit value for the fuel cell (41) of each of the plurality of fuel cell systems (4); and a power generation amount determination unit (23) that determines a target power generation amount for each of the plurality of fuel cell systems (4), the power generation amount determination unit (23) determining the target power generation amount on the basis of the required power generation amount and the output limit value.

Description

Technical Field

[0001] The present invention relates to a fuel cell power generation control system that can efficiently determine a target power generation amount for each fuel cell system with a small calculation load even when a failure occurs in a plurality of fuel cell systems. Background Art

[0002] In recent years, research and development of fuel cells, which contribute to improving energy efficiency, has been conducted to ensure that more people have access to appropriate, reliable, sustainable, and advanced energy.

[0003] Fuel cell vehicles that use fuel cells as one of their power sources include those equipped with multiple fuel cell systems, which are operated simultaneously based on the power requirements to achieve high output. In such vehicles, technologies have been developed to improve power generation efficiency by adjusting the operating timing and output of each of the multiple fuel cell systems.

[0004] For example, Patent Document 1 discloses the following technology: when the number of fuel cell systems operating according to the required power is changed and multiple fuel cell systems are operated simultaneously, the outputs of the fuel cell systems are made different, for example, by operating some fuel cell systems at an output near the optimal efficiency and other fuel cell systems at a minimum output that can generate power stably, thereby optimizing the power generation efficiency of the system as a whole.

[0005] Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Laid-Open No. 2022-034394 Summary of the Invention

[0006] Problems to be solved by the invention In systems where multiple fuel cell systems are operated at different outputs, as in the prior art described above, the degree of degradation of each fuel cell system varies, potentially shortening the overall system lifespan or increasing the frequency of maintenance. Therefore, to equalize degradation between fuel cell systems, attempts have been made to equalize the output of each fuel cell system as much as possible. In this case, for example, the target power generation of each of the N operating fuel cell systems is set to P / N relative to the required power generation P for the entire fuel cell system, thereby achieving output equivalence.

[0007] Typically, fuel cell systems set lower and upper limits for their output (power generation) during operation, and control is performed to ensure operation within these limits. The lower output limit (lower power limit) is determined based on degradation characteristics determined by the fuel cell system's design and typically does not change significantly over the system's lifetime. Meanwhile, the upper output limit (upper power limit) can vary even under normal conditions depending on factors such as the fuel cell's temperature and can also significantly decrease due to fuel cell degradation or failure.

[0008] In the case of a power generation system that equally distributes the required power generation to multiple fuel cell systems, if, for example, the upper limit power value of a fuel cell system is lower than the equally distributed target power generation due to a malfunction, control is required to redistribute the excess power generation to other fuel cell systems.

[0009] Figure 7 This diagram illustrates an example of redistribution control in the event of a failure in a power generation system that evenly distributes the requested power generation. In this example, four fuel cell systems (FCS1-4) are in use simultaneously. Since the requested power generation is evenly distributed among the four, each is assigned a target power generation of 25% of the requested power generation. However, the upper limit power values of two of the four systems (FCS1 and FCS2) have decreased compared to normal conditions, falling below the target power generation. In this situation, since even distribution is impossible, redistribution control is executed, and the power generation exceeding the upper limit is evenly distributed among the remaining two systems (FCS3 and FCS4). As a result, the target power generation allocated to FCS3 exceeds the upper limit power value, so redistribution control is executed again, and the excess power generation is allocated to FCS4.

[0010] As such, in a power generation system that performs control to evenly distribute the requested power generation among multiple fuel cell systems, if the upper limit power value of any of the multiple fuel cell systems decreases due to a failure or deterioration, the requested power generation may not be evenly distributed. Furthermore, the control to redistribute the power generation exceeding the upper limit power value to other fuel cell systems can complicate the redistribution control and increase the computational load, depending on the number of fuel cell systems in use, the number of fuel cell systems subject to output restriction, and the degree of output restriction.

[0011] The present invention was developed to address this issue. Its purpose is to provide a fuel cell power generation control system that, when output limitation occurs in any of a plurality of fuel cell systems, can efficiently determine the target power generation for each fuel cell system with a small computational load. Furthermore, this system further contributes to energy efficiency.

[0012] Technical solutions to problems In order to achieve this purpose, the fuel cell power generation control system involved in technical solution 1 of the present invention comprises: multiple fuel cell systems, each of which has a fuel cell capable of generating electricity through the reaction of fuel gas and oxidant gas; a required power generation acquisition unit, which acquires the required power generation for the multiple fuel cell systems; a limit value acquisition unit, which acquires the output limit value of the fuel cell of each of the multiple fuel cell systems; and a power generation determination unit, which determines the target power generation of each of the multiple fuel cell systems, and the power generation determination unit determines the target power generation based on the required power generation and the output limit value.

[0013] In this fuel cell power generation control system, a limit value acquisition unit acquires output limit values of fuel cells of each of the plurality of fuel cell systems, and a power generation amount determination unit determines target power generation amounts of each of the plurality of fuel cell systems based on the required power generation amounts and the output limit values.

[0014] Therefore, even if output limitation occurs in any of the multiple fuel cell systems due to failure, degradation, etc., the target power generation of each fuel cell system can be determined based on the required power generation and the output limit value in consideration of the output limitation.

[0015] This allows the target power generation amount of each fuel cell system to be determined efficiently with a small calculation load without having to repeat calculations for redistribution multiple times depending on the number of fuel cell systems with output restrictions or the degree of output restrictions.

[0016] The invention involved in technical solution 2 of the present invention is characterized in that, in the fuel cell power generation control system described in technical solution 1, the limit value acquisition unit obtains the upper limit value of the output of each fuel cell, that is, the upper limit power value, and the lower limit value of the output, that is, the lower limit power value, as the output limit value, and the power generation determination unit calculates the difference between the upper limit power value and the lower limit power value of each fuel cell as the power generation range, and then calculates the proportion of the power generation range of each fuel cell in the total power generation range of all fuel cells as the power generation ratio of each fuel cell, and determines the target power generation of each of the multiple fuel cell systems based on the required power generation and the power generation ratio.

[0017] According to this configuration, the power generation capacity determination unit calculates the difference between the upper and lower power limits of each fuel cell in the plurality of fuel cell systems as the power generation range of that fuel cell. Furthermore, the unit calculates the ratio of each fuel cell's power generation range to the total power generation range of all fuel cells as the power generation ratio of that fuel cell. The target power generation capacity of each of the plurality of fuel cell systems is then determined based on the calculated power generation ratios of each fuel cell and the required power generation capacity.

[0018] In this way, the power generation capacity of each fuel cell is pre-acquired as its ratio of available power generation relative to all fuel cells, and the target power generation amount is determined based on the ratio and the required power generation amount. Therefore, for example, when all fuel cells are operating normally and the available power generation ratios of each fuel cell are approximately equal, the required power generation amount can be distributed approximately equally among the fuel cells. Furthermore, even if the output of any fuel cell is limited due to a failure or deterioration, for example, the available power generation ratio corresponding to the degree of output limitation can be calculated, and the target power generation amount can be determined based on this available power generation ratio. This allows the target power generation amount to be determined efficiently with a low computational load, without exceeding the upper power limit of each fuel cell.

[0019] The invention involved in technical solution 3 of the present invention is characterized in that, in the fuel cell power generation control system described in technical solution 2, the power generation determination unit calculates the value obtained by subtracting the total value of the lower limit power values of all fuel cells from the required power generation and multiplies it by the power generation ratio of each fuel cell as the allocated power generation for each fuel cell, and adds the lower limit power value of each fuel cell to the allocated power generation as the target power generation of each of the multiple fuel cell systems.

[0020] According to this configuration, the power generation capacity determination unit calculates the total power generation capacity allocated to each fuel cell by multiplying the total power generation capacity that can be freely allocated to each fuel cell by the power generation capacity ratio of each fuel cell, i.e., the total power generation capacity that is obtained by subtracting the lower power limit values of all fuel cells from the required power generation capacity. The total power generation capacity of each fuel cell is then determined as the target power generation capacity for the fuel cell system including that fuel cell.

[0021] In this way, the allocated power generation capacity for each fuel cell is calculated by pre-calculating the total power generation capacity of each fuel cell by multiplying the value obtained by subtracting the total lower power limit of all fuel cells from the required power generation capacity by the power generation capacity ratio. The total of the allocated power generation capacity and the lower power limit is then used as the target power generation capacity for the fuel cell system. This allows the determination of a target power generation capacity that more accurately reflects the power generation capacity ratio of each fuel cell, thereby efficiently determining the target power generation capacity of each fuel cell system with a low computational load.

[0022] The control method of the fuel cell power generation control system involved in technical solution 4 of the present invention comprises: multiple fuel cell systems, each of which has a fuel cell capable of generating electricity through the reaction of fuel gas and oxidant gas; a required power generation acquisition unit, which acquires the required power generation for the multiple fuel cell systems; a limit value acquisition unit, which acquires the output limit value of the fuel cell of each of the multiple fuel cell systems; and a power generation determination unit, which determines the target power generation of each of the multiple fuel cell systems, and the power generation determination unit performs control to determine the target power generation based on the required power generation and the output limit value.

[0023] According to the control method of the fuel cell power generation control system, the power generation amount determination unit executes control to determine the target power generation amount of each of the plurality of fuel cell systems based on the required power generation amount and the output limit value.

[0024] Therefore, even if output limitation occurs in any of the multiple fuel cell systems due to failure, degradation, etc., the target power generation of each fuel cell system can be determined based on the required power generation and the output limit value in consideration of the output limitation.

[0025] This allows the target power generation amount of each fuel cell system to be determined efficiently with a small calculation load without having to repeat calculations for redistribution multiple times depending on the number of fuel cell systems with output restrictions or the degree of output restrictions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a diagram showing an example of a schematic configuration of a fuel cell vehicle equipped with a power generation control system according to an embodiment.

[0027] Figure 2 This is a diagram showing an example of a schematic configuration of an FC system according to the first embodiment.

[0028] Figure 3 This is a flowchart showing a control process for determining a target power generation amount in the power generation control system according to the embodiment.

[0029] Figure 4 This is a diagram for explaining how the target power generation amount is determined by the target power generation amount determination control during normal times.

[0030] Figure 5 This is a diagram for explaining how the target power generation amount is determined by the target power generation amount determination control during output limitation.

[0031] Figure 6 This is a table comparing the steps for determining the target power generation amount in the embodiment and the conventional technology.

[0032] Figure 7This is a diagram for explaining the procedure for determining the target power generation amount in the conventional technology for equally distributing the required power generation amount.

[0033] Figure 8 This is a diagram showing an example of a schematic configuration of an FC system according to the second embodiment. DETAILED DESCRIPTION

[0034] Below, a preferred embodiment of the fuel cell power generation control system of the present invention is described in detail with reference to the accompanying drawings. The fuel cell power generation control system involved in the first embodiment is installed in a fuel cell vehicle, and the electricity generated by the fuel cell is used as one of the power sources of the fuel cell vehicle. The fuel cell vehicle can be a two-wheeled, three-wheeled, or four-wheeled automobile, or it can be a large vehicle capable of carrying multiple fuel cell systems as described later. It should be noted that the structure described below illustrates the present invention, but the present invention is not limited to this.

[0035] <Schematic Structure of Fuel Cell Vehicle 100> Figure 1 This figure schematically illustrates the configuration of a fuel cell vehicle 100 equipped with a fuel cell power generation control system 1 according to the first embodiment. Fuel cell vehicle 100 is, for example, a fuel cell electric vehicle. As shown in the figure, fuel cell vehicle 100 includes a vehicle control device 101, a current controller 102, a motor 103, a battery 104, a management ECU (Electronic Control Unit) 2, a storage unit 3, and a fuel cell (FC) system 4.

[0036] exist Figure 1 In the example shown, four FC systems 4A, 4B, 4C, and 4D are shown, but the number of FC systems 4 installed is not limited to this. It should be noted that, when individual FC systems are not individually distinguished, they may simply be referred to as "FC system 4." The FC system 4 and the management ECU 2 constitute the power generation control system 1 in this embodiment. A configuration that includes the vehicle control device 101 as part of the power generation control system is also possible.

[0037] The motor 103 is, for example, a three-phase AC electric motor, and is driven by electricity supplied from the FC system 4 or the battery 104 via the current controller 102 as a power source. The rotor of the motor 103 is connected to drive wheels (not shown), and the motor 103 is controlled by the vehicle control device 101 to output driving force to the drive wheels for the fuel cell vehicle 100 to travel. Furthermore, the motor 103 uses the vehicle's kinetic energy to regenerate electricity during vehicle deceleration.

[0038] The battery 104 is, for example, a secondary battery such as a lithium-ion battery. The battery 104 stores power generated by the FC system 4 or the motor 103 and, under the control of the vehicle control device 101, supplies power to the motor 103 for driving the fuel cell vehicle 100. Furthermore, during startup of the FC system 4, the battery 104 supplies power to drive the auxiliary equipment of the FC system 4. After startup of the FC system 4, the battery 104 supplies the shortfall in power until the generated power of the FC system 4 reaches the required power.

[0039] The battery 104 is provided with sensors such as a current sensor, a voltage sensor, and a temperature sensor (not shown), and outputs current values, voltage values, temperatures, and the like detected by these sensors to the vehicle control device 101 .

[0040] The vehicle control device 101 is, for example, an ECU composed of a microcomputer including a CPU, RAM, ROM, and an I / O interface (none shown), and comprehensively controls the driving of the fuel cell vehicle 100 and the operation of in-vehicle devices (not shown).

[0041] The vehicle control device 101 controls the supply of power stored in the battery 104 and the power generated by the FC system 4 based on the power demanded by the fuel cell vehicle 100. The power demanded by the fuel cell vehicle 100 is the total load power required to drive and operate the motor 103, the braking system (not shown), various sensors, other onboard equipment, and auxiliary equipment.

[0042] The vehicle control device 101 can also control the travel of the fuel cell vehicle 100 , control the power running / regeneration drive of the motor 103 , and control the charge and discharge of the battery 104 .

[0043] The management ECU 2 is an ECU comprised of, for example, a microcomputer including a CPU, RAM, ROM, and an I / O interface (none of which are shown), and centrally controls multiple FC systems 4 (FC systems 4A, 4B, 4C, and 4D). The management ECU 2 includes a number of communication interfaces corresponding to the number of FC systems 4, each of which communicates with the target FC system 4.

[0044] As described later, the management ECU 2 obtains information regarding power supply instructions and required power generation for the FC system 4 from the vehicle control device 101 and, based on this information, determines the power generation of each FC system. The management ECU 2 includes functional units such as a required power generation acquisition unit 21, a limit value acquisition unit 22, and a power generation determination unit 23. Details of each functional unit will be described later.

[0045] Storage unit 3 is implemented using hardware such as an HDD (Hard Disk Drive), flash memory, EEPROM (Electrically Erasable Programmable Read Only Memory), ROM (Read Only Memory), or RAM (Random Access Memory). Storage unit 3 stores, for example, status information indicating the status of each FC system, as described later.

[0046] Each of the multiple FC systems 4 includes a fuel cell. A fuel cell generates electricity through an electrochemical reaction between a fuel gas supplied to an anode and an oxidant gas supplied to a cathode. In this embodiment, hydrogen is used as the fuel gas, and air containing oxygen is used as the oxidant gas.

[0047] As described later, the FC system 4 generates power according to a target power generation amount determined by the management ECU 2 , and supplies the generated power to the motor 103 or the battery 104 via the current controller 102 under the control of the vehicle control device 101 .

[0048] <Structure of FC System 4> Reference Figure 2 The specific structure of the FC system 4 will be described. Figure 2 This is a diagram showing an example of a schematic configuration of an FC system according to the embodiment. Figure 2 The structure shown can be applied to each of a plurality of FC systems 4 mounted on the fuel cell vehicle 100. The structure described below is merely an example, and any system structure may be used as long as it generates power using an anode and a cathode.

[0049] Figure 2 The illustrated FC system 4 includes an FC stack (fuel cell) 41 , an oxidant gas supplier 42 , a hydrogen supplier 43 , an FC controller 44 , a contactor 45 , an FCVCU (Fuel Cell Voltage Control Unit) 46 , an FC cooling system 47 , and a diluter 48 .

[0050] The FC stack 41 is a structure formed by stacking a plurality of power generation units 411. The FC stack 41 is provided with an oxidant gas inlet 41a, an oxidant gas outlet 41b, a hydrogen gas inlet 41c, a hydrogen gas outlet 41d, and electrodes 41e, 41e.

[0051] Each power generation unit 411 of the FC stack 41 has, for example, a structure in which a solid polymer electrolyte membrane (hereinafter referred to simply as an electrolyte membrane) 412 is sandwiched between an anode electrode 413 and a cathode electrode 414. This solid polymer electrolyte membrane 412 comprises, for example, a cation exchange membrane such as a thin film of perfluorosulfonic acid containing water. In addition to using a fluorine-based electrolyte, hydrocarbon-based electrolytes can also be used as the electrolyte membrane 412.

[0052] Hydrogen gas, a fuel gas containing hydrogen, is supplied from the hydrogen gas supply device 43 to the anode electrode 413. Air, an oxidant gas containing oxygen, is supplied from the oxidant gas supply device 42 to the cathode electrode 414. The hydrogen supplied to the anode electrode 413 is ionized by a catalytic reaction on the anode catalyst (not shown). The generated hydrogen ions permeate the electrolyte membrane 412 and move toward the cathode electrode 414. Electrons released by the ionization of hydrogen move to an external circuit via the electrode 41e, generating current and thus generating electricity. The hydrogen ions that move from the anode electrode 413 to the cathode electrode 414 react with the oxygen supplied to the cathode electrode 414 to produce water.

[0053] The oxidizing gas supply device 42 includes an air pump 421 for compressing air from the atmosphere and supplying the compressed air to the FC stack 41 . The air pump 421 is disposed in the air supply flow path 425 . The air pump 421 is driven and controlled by the FC control device 44 .

[0054] A humidifier 423 is provided in the air supply flow path 425 . The air supply flow path 425 communicates with the oxidant gas inlet 41 a of the FC stack 41 .

[0055] The oxidant gas outlet 41b is connected to an air exhaust passage 426 that passes through a humidifier 423. The humidifier 423 recovers moisture from the post-reaction air (including post-reaction gas and exhaust gas) discharged from the oxidant gas outlet 41b and passing through the air exhaust passage 426. This moisture is used to humidify the air passing through the air supply passage 425. This maintains the electrolyte membrane 412 in each power generation cell 411 of the FC stack 41 at a humidity suitable for power generation.

[0056] A supply-side sealing valve 422 is provided downstream of the air pump 421 in the air supply flow path 425. The supply-side sealing valve 422 is opened and closed by the FC control device 44, thereby switching the air supply flow path 425 between open and closed.

[0057] A discharge-side sealing valve 424 is provided in the air discharge passage 426. The discharge-side sealing valve 424 is opened and closed by the FC control device 44, thereby switching the air discharge passage 426 between open and closed. A diluter 48, described below, is connected downstream of the discharge-side sealing valve 424.

[0058] The hydrogen supply device 43 includes a hydrogen tank 431 storing high-pressure hydrogen. The hydrogen tank 431 communicates with the hydrogen inlet 41 c of the FC stack 41 via a hydrogen supply passage 437. An injector 432 and an ejector 433 are connected in series in the hydrogen supply passage 437.

[0059] The ejector 432 has its opening controlled by the FC control device 44 to regulate the flow rate and supply timing of hydrogen gas supplied to the FC stack 41. The ejector 433 draws the exhaust gas discharged from the hydrogen outlet 41d to the exhaust gas flow path 438 by creating a negative pressure inside the ejector 433 and circulates it to the hydrogen supply flow path 437.

[0060] An exhaust gas flow path 438 communicates with the hydrogen gas outlet 41 d of the FC stack 41 , and a gas-liquid separator 434 is connected to the exhaust gas flow path 438 .

[0061] The gas-liquid separator 434 separates the exhaust gas discharged from the hydrogen outlet 41d of the FC stack 41 into a gas component and a liquid component. The liquid component separated from the exhaust gas is discharged to the purge flow path 439 via a purge valve 435, which is controlled by the FC control device 44. Furthermore, a portion of the gas component separated from the exhaust gas is recirculated via the ejector 433, while the remaining portion is discharged to the purge flow path 439 via a purge valve 436, which is also controlled by the FC control device 44. The purge flow path is connected to the diluter 48.

[0062] The diluter 48 mixes the reacted air (including reacted gas and exhaust gas) discharged from the oxidant gas outlet 41 b of the FC stack 41 with the exhaust gas discharged from the hydrogen gas outlet 41 d of the FC stack 41 to dilute the hydrogen concentration to a predetermined value or less, and then discharges the mixture to the outside.

[0063] The contactor 45 is provided between the anode electrode 413 and the cathode electrode 414 of the FC stack 41 and the FCVCU 46 , and switches the electrical connection between the FC stack 41 and the FCVCU 46 on and off based on control by the FC control device 44 .

[0064] The FCVCU 46 is a step-up DC-DC converter. The FCVCU 46 is positioned between the anode electrode 413 and cathode electrode 414 of the FC stack 41 and an external electrical load of the FC system 4 via the contactor 45. The FCVCU 46 boosts the voltage at the output terminal 49 connected to the electrical load to a target voltage determined by the FC control unit 44. The FCVCU 46 boosts the voltage output from the FC stack 41 to the target voltage and outputs it to the output terminal 49.

[0065] The FC control device 44 is an ECU composed of a microcomputer including a CPU, RAM, ROM, and an I / O interface (none of which are shown), and is provided in each FC system 4 .

[0066] Each FC control device 44 is configured to acquire information related to the status of the FC system 4 to which it belongs based on detection values from various sensors (not shown). Each FC control device 44 acquires information related to the status of the FC system 4 continuously or in response to instructions from the management ECU 2, and transmits the acquired information to the management ECU 2.

[0067] The acquired FC system status includes, for example, the current power generation status, power generation amount, power generation time, number of starts (or stops), and more particularly, information on output limits in the FC stack 41. This output limit information includes the lower and upper power limits described below.

[0068] The FC control device 44 controls the start and end of power generation in the FC system 4, as well as the amount of power generated, according to the control of the management ECU 2. The FC control device 44 also controls the opening and closing of various valves in the FC system 4 and the drive of various auxiliary machines (such as the air pump 421). Furthermore, the FC control device 44 uses the FC cooling system 47 to control the temperature of the FC stack 41.

[0069] Furthermore, the FC control device 44 may also perform power supply control of the fuel cell vehicle 100 in cooperation with the management ECU 2 and the vehicle control device 101 .

[0070] The FC cooling system 47 cools the FC stack 41 under the control of the FC control device 44. For example, the FC cooling system 47 cools the FC stack 41 by circulating a refrigerant such as pure water or ethylene glycol through a refrigerant flow path (not shown) provided in the FC stack 41.

[0071] <Power Generation Operation of FC System 4> The power generation operation (power generation operation in the fuel cell stack 41 ) of the FC system 4 configured as described above will be described below.

[0072] The oxidant gas supply device 42 supplies air as oxidant gas to the air supply flow path 425 via the air pump 421. The air is humidified by the humidifier 423 and then supplied to the fuel cell stack 41 from the oxidant gas inlet 41a.

[0073] Meanwhile, the hydrogen supply device 43 supplies hydrogen from the hydrogen tank 431 to the hydrogen supply flow path 437 based on the opening control of the ejector 432 by the FC control device 44. The hydrogen passes through the ejector 433 and is then supplied to the FC stack 41 from the hydrogen inlet 41c.

[0074] Air supplied to the FC stack 41 from the oxidant gas inlet 41a is supplied to the cathode electrode 414 of each power generation unit 411, and hydrogen supplied to the FC stack 41 from the hydrogen gas inlet 41c is supplied to the anode electrode 413 of each power generation unit 411. Thus, in each power generation unit 411, hydrogen and oxygen in the air are consumed through an electrochemical reaction, generating electricity.

[0075] The electric power generated by the power generation is supplied to the battery 104 or the motor 103 through the current controller 102 based on the control of the FC control device 44 .

[0076] The air (including post-reaction gas and exhaust gas) after the reaction at the cathode electrode 414 of each power generation unit 411 is discharged from the oxidant gas outlet 41b to the air discharge flow path 426. After the discharged air passes through the humidifier 423 and moisture is recovered, it is introduced into the diluter 48. As described above, the moisture recovered by the humidifier 423 is used to humidify the air passing through the air supply flow path 425, thereby adjusting the humidity of the electrolyte membrane 412.

[0077] Furthermore, hydrogen gas after the reaction at the anode electrode 413 of each power generation unit 411 is discharged as exhaust gas (partially consumed fuel gas) from the hydrogen outlet 41d to the exhaust gas flow path 438. The exhausted exhaust gas is introduced from the exhaust gas flow path 438 to the gas-liquid separator 434, where the liquid water is separated. The exhaust gas is then recycled through the ejector 433 or discharged to the outside through the purge flow path 439.

[0078] Furthermore, during the execution of the above-described series of power generation operations, the FC cooling system 47 is driven according to the temperature of the FC stack 41 under the control of the FC control device 44 to cool the FC stack 41 .

[0079] <Structure of Management ECU 2> Next, the structure of the control system of the management ECU 2 will be described. Figure 1 As shown, the management ECU 2 includes a requested power generation amount acquisition unit 21, a limit value acquisition unit 22, and a power generation amount determination unit 23. These functional units 21-23 are implemented by, for example, a hardware processor such as the CPU of the management ECU 2 reading and executing a program (software). Such a program may be stored in the ROM or RAM included in the management ECU 2, or in a storage device (such as a non-transitory storage medium such as an HDD or flash memory) constituting the storage unit 3.

[0080] The required power generation amount acquisition unit 21 includes, for example, a communication interface unit for communicating with the vehicle control device 101. The required power generation amount acquisition unit 21 acquires, from the vehicle control device 101 via the communication interface unit, a command regarding the required power generation amount for the plurality of FC systems 4 (for example, the amount of power required for the entire fuel cell vehicle 100 excluding the power supplied by the battery 104).

[0081] The limit value acquisition unit 22 includes, for example, a plurality of communication interfaces corresponding to the number of FC systems 4. Through these communication interfaces, the limit value acquisition unit 22 acquires information on power generation limit values from various status-related information output from each FC system 4 at predetermined timings or cycles. Examples of these power generation limit values include an upper power limit value, which is the upper limit of the output (power generation) of each FC system 4, and a lower power limit value, which is the lower limit of the output (power generation) of each FC system 4. The limit value acquisition unit 22 stores the acquired information on the power generation limit values of each FC system 4 in the storage unit 3.

[0082] The power generation determination unit 23 executes target power generation determination control, described later, based on the required power generation for the FC system 4 obtained by the required power generation acquisition unit 21 and the power generation limit value obtained by the limit value acquisition unit 22, thereby determining the target power generation that each FC system 4 should generate.

[0083] Target power generation determination control Next, refer to Figures 3 to 6 The target power generation amount determination control in the power generation control system 1 of the present embodiment will be described. Figure 3 4 is a flowchart showing a control process for determining a target power generation amount in the present embodiment. This process is repeatedly executed at a predetermined timing or a predetermined cycle during power generation operation of the FC system 4, for example.

[0084] In this control process, the requested power generation acquisition unit 21 of the management ECU 2 first acquires the requested power generation for the entire FC system 4 (step 301 (shown as "S301" and the same applies hereinafter)). This requested power generation can be required for driving the fuel cell vehicle 100 or for driving and operating onboard equipment and auxiliary machines.

[0085] After acquiring the required power generation, the limit value acquisition unit 22 acquires an upper power limit and a lower power limit as output limits for each FC system 4 (step 302). During step 302, the limit value acquisition unit 22 may store the acquired upper power limit and lower power limit values for each FC system 4 in the storage unit 3 as limit value information. Furthermore, the process of step 302 may be repeated at a predetermined timing or cycle before executing step 301.

[0086] Next, in subsequent steps 303 to 306 , the power generation amount determination unit 23 determines the target power generation amount of each FC system 4 based on the acquired required power generation amount and the limit value information of each FC system 4 .

[0087] First, the power generation amount determination unit 23 calculates the power generation range for each FC system 4 based on the upper and lower power limits of each FC system 4 (step 303). This power generation range refers to the range of power values (output range) that can be generated by each FC system 4. In the present embodiment, it is calculated as the difference between the upper and lower power limits of each FC system 4.

[0088] Next, based on the calculated power generation range of each FC system 4, the ratio of the power generation range of each FC system 4 to the total power generation range of all FC systems 4 is calculated as the power generation ratio of that FC system 4 (step 304). The calculated power generation ratio serves as an indicator of the proportion of power generation that can be handled by that FC system 4.

[0089] Next, the power generation determination unit 23 calculates the value obtained by subtracting the total value of the lower limit power values in all FC systems 4 from the acquired required power generation, that is, the value of the power generation that can be freely allocated to each FC system 4 in the required power generation, and calculates the value obtained by multiplying this value by the power generation ratio of each FC system 4 as the allocated power generation for each FC system 4 (step 305).

[0090] Then, the total value of the lower limit power value and the allocated power generation amount of each FC system 4 is determined as the target power generation amount of the FC system 4 (step 306 ), after which the present process ends.

[0091] Figure 4 and Figure 5 1 is a diagram for explaining how the target power generation amount is determined by the target power generation amount determination control in this embodiment. Figure 4 The target power generation is determined under normal conditions. Figure 5 The target power generation amount is determined when output limitation occurs in a part of the FC system 4 .

[0092] First, refer to Figure 4The process for determining the target power generation during normal operation will be described. First, the available power generation range is calculated based on the upper and lower power limits of each of the four FC systems 4 (FCS1-4). The available power generation ranges of all FC systems 4 are then combined to calculate the overall available power generation range. The available power generation ratio for each FC system 4 is then calculated. In this example, since each FC system 4 is operating normally (without upper power limits), the available power generation ranges of each FC system 4 are approximately equal, and therefore the available power generation ratios of each FC system 4 are also equal. Since four FC systems 4 are used here, the available power generation ratio for each FC system 4 is 25%.

[0093] Next, the lower limit power value of each FC system 4 is subtracted from the required power generation, and the allocated power generation amount is calculated based on the calculated available power generation ratio. The calculated allocated power generation amount is then added to the lower limit power value, and the resulting value is determined as the target power generation amount for each FC system 4.

[0094] Thus, when the upper limit power value of each FC system 4 is not restricted and the range of available power generation is approximately the same, the target power generation capacity of each FC system 4 is the same as the target power generation capacity of each FC system 4 when the required power generation is evenly distributed according to the number of FC systems 4. Furthermore, because the target power generation capacity for each FC system 4 is determined based on the available power generation ratio, there is no possibility of exceeding the upper limit power value.

[0095] Next, refer to Figure 5 , the process of determining the target power generation amount when output limitation occurs in one of the four FC systems 4 (FCS1) will be described. Figure 4 Similarly, the available power generation range is calculated based on the upper and lower power limits of each of the four FC systems (FCS1-4). In this example, the upper power limit of FCS1 has decreased due to a failure or deterioration, reducing the available power generation range to approximately one-third of its normal value. Therefore, the available power generation ratio for each FC system is 10% for FCS1 and 30% for FCS2-4.

[0096] Then, with Figure 4 Similarly to the example of , the allocated power generation amount for each FC system 4 is calculated based on the available power generation ratio, and the target power generation amount is determined by adding the allocated power generation amount to the lower limit power value.

[0097] In this way, even if an output restriction occurs in any of the multiple FC systems 4 and the upper limit power value decreases, the target power generation can be determined based on the proportion of power that can be generated by the FC system 4 that has the output restriction. Therefore, the target power generation will not exceed the upper limit power value, and each FC system 4 can operate efficiently with an appropriate output.

[0098] Furthermore, in this target power generation determination control, the proportion of power generation available for each FC system 4 is first calculated, and the required power generation is allocated accordingly, thereby determining the target power generation for each FC system 4. Therefore, even if there are changes in the number of FC systems 4 used, the number of FC systems 4 with output restrictions, the degree of output restriction, etc., the target power generation can be determined using the same control flow with a small computational load, without the need for further calculations.

[0099] Figure 6 This table compares the target power generation amount determination control of this embodiment with the steps of determining the target power generation amount in the conventional technology that evenly distributes the required power generation amount. Figure 6 In this example, the required power generation for the entire FC system 4 is 100 kW. Four FC systems 4 are used (FCS1-4). The upper limit power of each FC system 4 during normal operation is 60 kW. To avoid complication, the lower limit power of each FC system 4 is set to 0 kW for convenience.

[0100] Figure 6 (a) shows the procedure for determining the target power generation amount in normal times (when no output limitation occurs in each FC system 4 ).

[0101] First, in the conventional technology, the target power generation is obtained by evenly distributing the required power generation amount by the number of FC systems 4 . Therefore, 100 kW / 4=25 kW is the target power generation amount of each FC system 4 .

[0102] On the other hand, in this embodiment, as previously described, the available power generation ratio is calculated based on the available power generation range of each FC system 4 (upper power limit minus lower power limit). Since the available power generation range of each FC system 4 is 60 kW, the available power generation ratio is equal, at 25%. Therefore, the target power generation capacity of each FC system 4 is the required power generation capacity (100 kW x 0.25 = 25 kW).

[0103] As described above, in determining the target power generation amount in normal times, the present embodiment and the conventional technology produce the same results.

[0104] Next, refer to Figure 6 In (b), a case where output limitation occurs in one (FCS1) of the four FC systems 4 is considered.

[0105] In the conventional technology, the required power generation of 100 kW is first evenly distributed, with 25 kW allocated to each FC system 4. However, since the upper limit power value of FCS1 has been reduced to 20 kW, the target power generation exceeds the upper limit power value. Therefore, the excess power of 5 kW in FCS1 is evenly distributed again among FCSs 2 to 4, and the target power generation of FCSs 2 to 4 is set to 25 kW + (5 kW / 3) ≈ 27 kW. The target power generation of FCS 1 is set to the upper limit power value of 20 kW.

[0106] Meanwhile, in this embodiment, the available power generation ratio is calculated based on the available power generation range (upper power limit - lower power limit) of each FC system 4, as in normal operation. In this example, since the available power generation range of FCS1 has been reduced to 20 kW, the available power generation ratio for FCS1 is 10% (20 kW / 200 kW), and for FCSs 2 through 4 it is 30% (60 kW / 200 kW). Consequently, the target power generation for each FC system 4 is 100 kW × 0.1 = 10 kW for FCS1, and 100 kW × 0.3 = 30 kW for FCSs 2 through 4.

[0107] In this manner, in a system that determines target power generation by equally distributing required power generation as in the conventional art, output limitation may occur in any FC system 4, requiring redistribution control processing, increasing the computational load.

[0108] On the other hand, in the present embodiment, even when output limitation occurs in any FC system 4 , the target power generation amount can be efficiently determined by the same control process as in normal times.

[0109] Finally, refer to Figure 6 In (c), a case where output limitation occurs in a plurality of the four FC systems 4 (FCS1 to 3) is examined.

[0110] In the conventional technique, the requested power generation capacity of 100 kW is first evenly distributed, with 25 kW allocated to each FC system 4. Since the upper power limits for FCS1 and FCS2 are 10 kW, the target power generation capacity exceeds these limits. Therefore, the excess power of 15 kW in FCS1 and 15 kW in FCS2, totaling 30 kW, is evenly distributed among FCSs 3 and 4. As a result, the upper power limit of 10 kW is allocated to FCSs 1 and 2, while 25 kW + (30 kW / 2) = 40 kW is allocated to each of FCSs 3 and 4. However, since the upper power limit for FCS 3 is 30 kW, this 10 kW excess power is exceeded, necessitating redistribution of this excess power to FCS 4. Consequently, the final target power generation capacity is set at 10 kW for each of FCSs 1 and 2, 30 kW for FCS 3, and 50 kW for FCS 4.

[0111] Meanwhile, in this embodiment, the available power generation ratio is calculated based on the available power generation range (upper power limit minus lower power limit) of each FC system 4, as in normal operation. In this example, the available power generation range of FCS1 and FCS2 is reduced to 10 kW, and that of FCS3 is reduced to 30 kW. Therefore, the available power generation ratio for FCS1 and FCS2 is 9% (10 kW / 110 kW), 27% (30 kW / 110 kW) for FCS3, and 55% (60 kW / 110 kW) for FCS4. Consequently, the target power generation for each FC system 4 is 100 kW × 0.09 = 9 kW for FCS1 and FCS2, 100 kW × 0.27 = 27 kW for FCS3, and 100 kW × 0.55 = 55 kW for FCS4.

[0112] As described above, in the conventional technology, depending on the number of FC systems 4 subject to output restriction and the degree of output restriction, control processing requiring multiple rounds of redistribution may be necessary, and in such cases, the computational load becomes extremely large.

[0113] On the other hand, in the target power generation determination control of the present embodiment, even if output restrictions occur in multiple FC systems 4 or the degree of output restrictions varies, an appropriate target power generation can be determined efficiently with a small calculation load through the same control processing as in normal times.

[0114] <Effects of this embodiment> Hereinafter, the effects of this embodiment will be described.

[0115] According to this embodiment, during the target power generation capacity determination control of the fuel cell power generation control system 1, the limit value acquisition unit 22 of the management ECU 2 acquires the output limit value of each FC system 4, and the power generation capacity determination unit 23 determines the target power generation capacity of each FC system 4 based on the requested power generation capacity and the output limit value. Therefore, even if any of the multiple FC systems 4 experiences output limitations due to a failure, deterioration, or the like, the target power generation capacity of each FC system 4 can be determined based on the requested power generation capacity and the output limit value, taking into account the output limitations.

[0116] This eliminates the need to change the control flow or repeat calculations for redistribution depending on the number of FC systems 4 with output restrictions or the degree of output restrictions, and allows efficient determination of the target power generation amount of each FC system 4 with a small calculation load.

[0117] The power generation capacity determination unit 23 also calculates the difference between the upper and lower power limits for each of the multiple FC systems 4 (the FC stacks 41 thereof) as the power generation range available for that FC system 4. Furthermore, the unit calculates the ratio of the power generation range for each FC system 4 to the total power generation range for all FC systems 4 as the power generation ratio for that FC system 4. The target power generation capacity for each FC system 4 is then determined based on the calculated power generation ratio and the required power generation capacity.

[0118] In this way, the power generation capacity of each FC system 4 is pre-acquired as its available power generation ratio relative to all FC systems 4, and the target power generation capacity is determined based on the available power generation ratio and the required power generation capacity. Therefore, for example, when all FC systems 4 are operating normally and the available power generation ratios of each FC system 4 are approximately equal, the required power generation capacity can be distributed approximately equally among each FC system 4. Furthermore, even if output is limited in any FC system 4 due to a failure, deterioration, or the like, the available power generation ratio corresponding to the degree of output limitation can be calculated, and the target power generation capacity can be determined based on this available power generation ratio. This allows the target power generation capacity to be determined efficiently with a low computational load, without exceeding the upper power limit of each FC system 4.

[0119] The power generation capacity determination unit 23 then calculates the allocated power generation capacity for each FC system 4 by multiplying the total value of the lower-limit power values of all FC systems 4 from the required power generation capacity by the available power generation ratio of each FC system 4. The total value of the lower-limit power value and the allocated power generation capacity for each FC system 4 is then determined as the target power generation capacity for that FC system 4.

[0120] In this way, the allocated power generation capacity for each FC system 4 is preliminarily calculated by multiplying the value obtained by subtracting the total lower-limit power values of all FC systems 4 from the required power generation capacity by the available power generation ratio. The total of the allocated power generation capacity and the lower-limit power value is then used as the target power generation capacity for that FC system 4. This allows the determination of a target power generation capacity that more accurately reflects the available power generation ratio of each FC system 4, thereby enabling the efficient determination of the target power generation capacity for each FC system 4 with a small computational load.

[0121] Next, refer to Figure 8 A second embodiment of the fuel cell power generation control system of the present invention is described, in which the fuel cell power generation control system is applied to stationary equipment such as homes and factories. In the following description, components identical to those of the fuel cell power generation control system 1 of the first embodiment are denoted by the same reference numerals, and their description is omitted.

[0122] like Figure 8 As shown, the fuel cell power generation control system 10 involved in the second embodiment is installed in a fixed device 200 such as a residence or factory, and functions as an auxiliary power supply device to supply the insufficient power when the power required in the fixed device 200 exceeds the power supplied by the main power supply device.

[0123] The stationary power supply control device 201 is an ECU composed of a microcomputer including, for example, a CPU, a RAM, a ROM, and an I / O interface (none of which are shown).

[0124] In the power generation control system 1 of the first embodiment, the vehicle control device 101 controls the supply of generated power, etc. based on the required power from the fuel cell vehicle 100, but in the power generation control system 10 of the second embodiment, the fixed power supply control device 201 controls the supply of power stored in the battery 104 and the power generated by the FC system 4, etc. based on the required power from a higher-level power management device (not shown).

[0125] The configuration and function of the management ECU 2 in the power generation control system 10 are the same as those in the power generation control system 1 .

[0126] The management ECU 2 obtains information related to power supply instructions and required power generation for the FC systems 4 from the stationary power supply control device 201. Based on this information, the management ECU 2 executes the target power generation determination control described above to determine the target power generation for each FC system 4. The required power generation acquisition unit 21 of the management ECU 2 includes, for example, a communication interface for communicating with the stationary power supply control device 201. The management ECU 2 obtains instructions related to the required power generation for the multiple FC systems 4 from the stationary power supply control device 201 via this communication interface.

[0127] The configuration and function of the FC system 4 in the power generation control system 10 are also the same as those in the power generation control system 1 .

[0128] The FC system 4 generates electricity according to the target power generation amount determined by the target power generation amount determination control of the management ECU 2. The generated electricity is supplied to the battery 104 or the inverter 202 via the current controller 102 under the control of the stationary power supply control device 201. The inverter 202 converts the supplied DC power into AC power and supplies it to the stationary equipment 200.

[0129] In this way, the fuel cell power generation control system of the present invention can also be applied to fixed-type equipment such as residences and factories. Similar to the case of being mounted on mobile objects such as vehicles, there is no need to change the control process or repeatedly perform calculations for redistribution based on the number of FC systems 4 that have output restrictions or the degree of output restrictions. The target power generation of each FC system 4 can be efficiently determined with a small computational load.

[0130] The present invention is not limited to the embodiment described above, but can be implemented in various forms. Furthermore, the structure of the detailed part can be appropriately changed within the scope of the gist of the present invention.

[0131] Explanation of symbols 1: Fuel cell power generation control system 2: Management ECU 21: Required power generation amount acquisition unit (required power generation amount acquisition unit) 22: Limit value acquisition unit (limit value acquisition unit) 23: Power generation determination unit (power generation determination unit) 3: Storage 4: FC system (fuel cell system) 41: FC stack (fuel cell) 42: Oxidant gas supply device 43: Hydrogen supply device 44: FC control device 100: Fuel cell vehicles 101: Vehicle Control Devices 103: Motor 104: Battery.

Claims

1. A fuel cell power generation control system comprising: a plurality of fuel cell systems, each including a fuel cell capable of generating electricity through a reaction between a fuel gas and an oxidant gas; a requested power generation amount acquisition unit that acquires requested power generation amounts for the plurality of fuel cell systems; a limit value acquisition unit that acquires an output limit value of the fuel cell in each of the plurality of fuel cell systems; and a power generation amount determination unit that determines a target power generation amount for each of the plurality of fuel cell systems; The power generation amount determination unit determines the target power generation amount based on the required power generation amount and the output limit value.

2. The fuel cell power generation control system according to claim 1, characterized in that: The limit value acquisition unit acquires an upper limit power value, which is an upper limit value of the output of each fuel cell, and a lower limit power value, which is a lower limit value of the output, as the output limit value. After calculating the difference between the upper limit power value and the lower limit power value of each fuel cell as the power generation range, the power generation determination unit calculates the ratio of the power generation range of each fuel cell to the total power generation range of all the fuel cells as the power generation ratio of each fuel cell, and determines the target power generation of each of the multiple fuel cell systems based on the required power generation and the power generation ratio.

3. The fuel cell power generation control system according to claim 2, characterized in that: The power generation determination unit calculates the value obtained by subtracting the total value of the lower limit power values of all the fuel cells from the required power generation and multiplies it by the power generation ratio of each fuel cell as the allocated power generation for each fuel cell, and uses the value obtained by adding the lower limit power value of each fuel cell to the allocated power generation as the target power generation of each of the multiple fuel cell systems.

4. A control method for a fuel cell power generation control system, comprising: a plurality of fuel cell systems, each including a fuel cell capable of generating electricity through a reaction between a fuel gas and an oxidant gas; a required power generation amount acquisition unit that acquires required power generation amounts for the plurality of fuel cell systems; a limit value acquiring unit configured to acquire an output limit value of the fuel cell of each of the plurality of fuel cell systems; and A power generation amount determination unit determines a target power generation amount for each of the plurality of fuel cell systems. The power generation amount determination unit performs control to determine the target power generation amount based on the required power generation amount and the output limit value.

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