Fuel cell system

Abstract

The present invention provides a fuel cell system that reduces voltage fluctuations in the fuel cell unit. [Solution] The fuel cell system comprises a plurality of fuel cell units electrically connected in parallel and a control unit. Each of the plurality of fuel cell units includes a converter and a power generation unit, and the control unit controls the power generation unit so that the input voltage value to the converter of each of the plurality of fuel cell units is the same.

Description

Technical Field

[0001] The present disclosure relates to a fuel cell system.

Background Art

[0002] In recent years, fuel cell systems including a plurality of fuel cells have been known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Regarding fuel cell systems, there is room for improvement in terms of reducing voltage variation among each of a plurality of fuel cell units.

Means for Solving the Problems

[0005] One aspect of the present disclosure is a fuel cell system including a plurality of fuel cell units electrically connected in parallel, and a control unit, wherein each of the plurality of fuel cell units includes a converter and a power generation section, and the control unit controls the power generation section such that input voltage values to the converter of each of the plurality of fuel cell units are equal.

Effects of the Invention

[0006] Voltage variation among each of the plurality of fuel cell units can be reduced compared to a case where the configuration of the present disclosure is not used.

Brief Description of the Drawings

[0007] [Figure 1] Figure 1 is a diagram showing the configuration of the fuel cell system according to the embodiment. [Figure 2] Figure 2 shows the configuration of a fuel cell unit according to an embodiment. [Figure 3] Figure 3 shows the configuration of the power generation unit according to the embodiment. [Figure 4] Figure 4 is a flowchart illustrating the control of the fuel cell system according to the embodiment. [Figure 5] Figure 5 is a flowchart illustrating the control of the fuel cell system according to modification example 1. [Modes for carrying out the invention]

[0008] Embodiments will be described below with reference to the drawings. In the drawings, the same reference numerals are used for parts having the same configuration and function, and the drawings are schematic representations.

[0009] [Embodiment] (Fuel cell system) As shown in Figure 1, the fuel cell system 1 comprises a load group 2, an integrated control unit 10, and a plurality of fuel cell units 20. In this embodiment, the fuel cell system 1 includes three fuel cell units 20. However, the fuel cell system 1 is not limited to including three fuel cell units 20. Each of the plurality of fuel cell units 20 is electrically connected in parallel.

[0010] <Load group> Load group 2 consists of devices that consume electricity. Load group 2 may include, for example, an air conditioner, a water heater, and a lighting device. Load group 2 may request the fuel cell system 1 to supply the electricity consumed by load group 2. Load group 2 may transmit request current information to the fuel cell system 1 indicating the current requested by load group 2.

[0011] <Integrated Control Unit> The integrated control unit 10 comprises a first communication unit 11, a first storage unit 12, and a first control unit 13. The integrated control unit 10 controls multiple unit integrated control units 21 or power generation units 40 via a communication line. The integrated control unit 10 may also remotely control multiple unit integrated control units 21 or power generation units 40 via a communication line.

[0012] The first communication unit 11 communicates with the unit integrated control unit 21 or the power generation unit 40. The first communication unit 11 receives, for example, at least one of the following: input voltage value information, drive information for the oxygen-containing gas supply unit 44, drive information for the fuel gas supply unit 45, drive information for the reformed water supply unit 46, temperature information for the power generation unit 40, power generation voltage information for the power generation unit 40, and power generation unit 40 current information. The first communication unit 11 receives, for example, control signals from the unit integrated control unit 21 or the power generation unit 40. The first communication unit 11 transmits, for example, control signals to the unit integrated control unit 21 or the power generation unit 40. The first communication unit 11 includes a communication module capable of communicating with the unit integrated control unit 21 or the power generation unit 40. The communication module is a module compliant with the communication standard between the integrated control unit 10 and the unit integrated control unit 21, or between the integrated control unit 10 and the power generation unit 40. Communication between the integrated control unit 10 and the unit integrated control unit 21, or between the integrated control unit 10 and the power generation unit 40, may be wired or wireless. The first communication unit 11 may include a communication module capable of communicating with an external device such as a remote controller. The first communication unit 11 may also have the functions of the first control unit 13.

[0013] The first storage unit 12 stores data related to the integrated control unit 10. The first storage unit 12 includes semiconductor memory, magnetic memory, optical memory, or a combination thereof. The first storage unit 12 may also function as a main memory, auxiliary memory, or cache memory.

[0014] The first control unit 13 controls the integrated control unit 10, the unit integrated control unit 21, or the power generation unit 40. The first control unit 13 generates a control signal based on, for example, at least one of the following pieces of information: input voltage value information, drive information for the oxygen-containing gas supply unit 44, drive information for the fuel gas supply unit 45, drive information for the reformed water supply unit 46, temperature information for the power generation unit 40, power generation voltage information for the power generation unit 40, and current information for the power generation unit 40. The first control unit 13 includes a processor, a dedicated circuit, or a combination thereof. The processor is, for example, a CPU (Central Processing Unit) or This is a processor such as a GPU (Graphics Processing Unit). The processor may be a dedicated processor specialized for a specific process. The dedicated circuit may be, for example, an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). The first control unit 13 may have the functions of the first communication unit 11.

[0015] <Fuel cell unit> As shown in Figure 2, the fuel cell unit 20 comprises a unit integrated control unit 21, a converter 30, a power generation unit 40, and a current sensor 50. In this embodiment, the fuel cell unit 20 includes three power generation units 40. However, the fuel cell unit 20 is not limited to including three power generation units 40. Each of the multiple power generation units 40 included in the fuel cell unit 20 is electrically connected in series.

[0016] The unit integrated control unit 21 includes a second communication unit 22, a second storage unit 23, and a second control unit 24. The unit integrated control unit 21 controls the multiple power generation units 40 via a communication line. The unit integrated control unit 21 may also remotely control the multiple power generation units 40 via a communication line.

[0017] The second communication unit 22 communicates with the integrated control unit 10 or the power generation unit 40. The second communication unit 22 receives at least one piece of information from, for example, input voltage value information, drive information of the oxygen-containing gas supply unit 44, drive information of the fuel gas supply unit 45, drive information of the reformed water supply unit 46, temperature information of the power generation unit 40, power generation voltage information of the power generation unit 40, and current information of the power generation unit 40. The second communication unit 22 receives a control signal from, for example, the integrated control unit 10 or the power generation unit 40. The second communication unit 22 transmits a control signal to, for example, the integrated control unit 10 or the power generation unit 40. The second communication unit 22 includes a communication module capable of communicating with the integrated control unit 10 or the power generation unit 40. The communication module is a module compliant with the communication standard between the integrated control unit 10 and the unit integrated control unit 21, or between the unit integrated control unit 21 and the power generation unit 40. Communication between the integrated control unit 10 and the unit integrated control unit 21, or between the unit integrated control unit 21 and the power generation unit 40 may be wired or may be implemented wirelessly. The second communication unit 22 may include a communication module capable of communicating with an external device such as a remote controller. The second communication unit 22 may have the function of the second control unit 24.

[0018] The second storage unit 23 stores data related to the unit integrated control unit 21. The second storage unit 23 includes a semiconductor memory, a magnetic memory, an optical memory, or a combination thereof. The second storage unit 23 may have a function as a main storage device, an auxiliary storage device, or a cache memory.

[0019] The second control unit 24 controls the unit integrated control unit 21 or the power generation unit 40. The second control unit 24 creates a control signal based on at least one piece of information from, for example, input voltage value information, drive information of the oxygen-containing gas supply unit 44, drive information of the fuel gas supply unit 45, drive information of the reformed water supply unit 46, temperature information of the power generation unit 40, power generation voltage information of the power generation unit 40, and current information of the power generation unit 40. The second control unit 24 includes a processor, a dedicated circuit, or a combination thereof. The processor is, for example, a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). The processor is a dedicated pro It may also be a processor. The dedicated circuit is, for example, an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). The second control unit 24 may have the function of the second communication unit 22.

[0020] The converter 30 converts the input voltage value from the power generation unit 40 to the converter 30 into a predetermined voltage value. The input voltage value is, for example, a voltage value input from the power generation unit 40 to the converter 30. The input voltage value may be a voltage value predicted to be input from the power generation unit 40 to the converter 30. The converter 30 is, for example, a DC / DC converter. The converter 30 transmits input voltage value information indicating the input voltage value from the power generation unit 40 to the converter 30 to the second control unit 24.

[0021] As shown in Figure 3, the power generation unit 40 includes a third communication unit 41, a third storage unit 42, a third control unit 43, an oxygen-containing gas supply unit 44, a fuel gas supply unit 45, reformed water supply unit 46, and a fuel cell module 47.

[0022] The third communication unit 41 communicates with the integrated control unit 10 or the unit integrated control unit 21. The third communication unit 41 receives at least one piece of information from, for example, input voltage value information, drive information of the oxygen-containing gas supply unit 44, drive information of the fuel gas supply unit 45, drive information of the reformed water supply unit 46, temperature information of the power generation unit 40, generated voltage information of the power generation unit 40, and current information of the power generation unit 40. The third communication unit 41 receives a control signal from, for example, the integrated control unit 10 or the unit integrated control unit 21. The third communication unit 41, for example, transmits to the integrated control unit 10 or the unit integrated control unit 21 In response, it transmits control signals. The third communication unit 41 includes a communication module capable of communicating with the integrated control unit 10 or the unit integrated control unit 21. The communication module is a module compliant with the communication standard between the integrated control unit 10 and the power generation unit 40, or between the unit integrated control unit 21 and the power generation unit 40. Communication between the integrated control unit 10 and the power generation unit 40, or between the unit integrated control unit 21 and the power generation unit 40, may be wired or wireless. The third communication unit 41 may also include a communication module capable of communicating with external devices such as a remote controller. The third communication unit 41 may also have the functions of the third control unit 43.

[0023] The third storage unit 42 stores data related to the power generation unit 40. The third storage unit 42 includes semiconductor memory, magnetic memory, optical memory, or a combination thereof. The third storage unit 42 may also function as a main memory, auxiliary memory, or cache memory.

[0024] The third control unit 43 controls the power generation unit 40. The third control unit 43 includes a processor, a dedicated circuit, or a combination thereof. The processor is, for example, a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). The processor is, A dedicated processor specialized for a specific process may be used. Examples of such dedicated circuits include FPGAs (Field-Programmable Gate Arrays) or ASICs (Application Specific Integrated Circuits). The third control unit 43 may predict the voltage value input to the converter 30 included in the fuel cell unit 20. The third control unit 43 may also have the functions of the third communication unit 41.

[0025] The oxygen-containing gas supply unit 44 supplies oxygen-containing gas to the fuel cell module 47. The oxygen-containing gas supply unit 44 may supply air as the oxygen-containing gas. The oxygen-containing gas supply unit 44 is connected to the fuel cell module 47. The connection between the oxygen-containing gas supply unit 44 and the fuel cell module 47 may include piping or valves. The oxygen-containing gas supply unit 44 includes a blower or the like. The oxygen-containing gas supply unit 44 may heat air taken in from the outside and supply it to the fuel cell module 47. This can reduce the temperature inside the fuel cell module 47 from dropping due to the air taken in from the outside, thereby potentially improving the power generation efficiency of the fuel cell module 47.

[0026] The oxygen-containing gas supply unit 44 communicates with the third control unit 43. The oxygen-containing gas supply unit 44 receives, for example, a control signal from the third control unit 43. The oxygen-containing gas supply unit 44 controls, for example, the flow rate of oxygen-containing gas supplied to the fuel cell module 47 based on the control signal. The oxygen-containing gas supply unit 44 transmits, for example, drive information of the oxygen-containing gas supply unit 44 to the third control unit 43, indicating the rotational speed or drive number of the oxygen-containing gas supply unit 44.

[0027] The oxygen-containing gas flow meter 441 measures the flow rate of oxygen-containing gas flowing through piping or valves between the oxygen-containing gas supply unit 44 and the fuel cell module 47. The oxygen-containing gas flow meter 441 is attached to the piping or valves between the oxygen-containing gas supply unit 44 and the fuel cell module 47. The oxygen-containing gas flow meter 441 transmits the measurement result of the oxygen-containing gas flow rate to, for example, the third control unit 43. The power generation unit 40 may also include the oxygen-containing gas flow meter 441.

[0028] The fuel gas supply unit 45 supplies fuel gas to the fuel cell module 47. The fuel gas supply unit 45 may supply methane-containing gas as fuel gas. The fuel gas supply unit 45 is connected to the fuel cell module 47. The connection between the fuel gas supply unit 45 and the fuel cell module 47 may include piping or valves. The fuel gas supply unit 45 includes a pump or the like.

[0029] The fuel gas supply unit 45 communicates with the third control unit 43. The fuel gas supply unit 45, for example, The third control unit 43 receives a control signal. The fuel gas supply unit 45 controls the flow rate of fuel gas supplied to the fuel cell module 47 based on the control instruction. The fuel gas supply unit 45 transmits to the third control unit 43, for example, drive information of the fuel gas supply unit 45 indicating the rotational speed or drive number of the fuel gas supply unit 45.

[0030] The fuel gas flow meter 451 measures the flow rate of fuel gas flowing through piping or valves between the fuel gas supply unit 45 and the fuel cell module 47. The fuel gas flow meter 451 is attached to the piping or valves between the fuel gas supply unit 45 and the fuel cell module 47. The fuel gas flow meter 451 transmits the measurement result of the fuel gas flow rate to, for example, the third control unit 43. The power generation unit 40 may also include the fuel gas flow meter 451.

[0031] The reformed water supply unit 46 supplies reformed water to the fuel cell module 47. The reformed water supply unit 46 is connected to the fuel cell module 47. The connection between the reformed water supply unit 46 and the fuel cell module 47 may include piping or valves. The reformed water supply unit 46 includes a pump.

[0032] The reformed water supply unit 46 communicates with the third control unit 43. The reformed water supply unit 46 receives, for example, a control instruction from the third control unit 43. Based on the control instruction, the reformed water supply unit 46 controls the flow rate of reformed water supplied to the fuel cell module 47. The reformed water supply unit 46 transmits drive information of the reformed water supply unit 46, indicating the rotational speed or drive number of the reformed water supply unit 46, to the third control unit 43.

[0033] The reformed water flow meter 461 measures the flow rate of reformed water flowing through piping or valves between the fuel gas supply unit 45 and the fuel cell module 47. The reformed water flow meter 461 may be, for example, an acceleration sensor. The reformed water flow meter 461 is attached to piping or valves between the fuel gas supply unit 45 and the fuel cell module 47. The reformed water flow meter 461 transmits the measurement result of the reformed water flow rate to, for example, the third control unit 43. The power generation unit 40 may include the reformed water flow meter 461.

[0034] The fuel cell module 47 generates electricity by an electrochemical reaction using a hydrogen-containing fuel gas and an oxygen-containing gas supplied from an oxygen-containing gas supply unit 44. The fuel cell module 47 is not limited to one unit, but may consist of two or more units. The fuel cell module 47 may include a reformer that generates a hydrogen-containing fuel gas using reformed water and raw fuel gas. The fuel cell module 47 may also include a combustion unit that burns unreacted fuel gas or unreacted oxygen-containing gas in the fuel cell stack.

[0035] A fuel cell stack is a solid oxide fuel cell (SOFC). ) may also be used. However, the fuel cell stack is not limited to solid oxide fuel cells.

[0036] The fuel cell module 47 is equipped with a temperature sensor 471. The temperature sensor 471 detects the temperature of the fuel cell module 47. The temperature sensor 471 is located in a position where it can detect the temperature of the fuel cell module 47. The temperature sensor 471 transmits temperature information indicating the value of the temperature of the fuel cell module 47 to the third control unit 43.

[0037] The fuel cell module 47 is equipped with a voltage sensor 472. The voltage sensor 472 detects the generated voltage of the fuel cell module 47. The voltage sensor 472 is located in a position where it can detect the generated voltage produced by the fuel cell module 47. The voltage sensor 472 transmits generated voltage information, which indicates the value of the generated voltage of the fuel cell module 47, to the third control unit 43.

[0038] The current sensor 50 detects the current flowing through the fuel cell unit 20. The current sensor 50 transmits current information indicating the value of the current in the fuel cell unit 20 to the third control unit 43.

[0039] (Processing by the integrated control unit) <Electrically parallel-connected fuel cell units> As shown in Figure 1, when multiple fuel cell units 20 are electrically connected in parallel, there may be individual differences in the power generation unit 40. Individual differences include, for example, errors in the power generation voltage value of the fuel cell module 47. Individual differences also include, for example, errors in the gas supply amount of the oxygen-containing gas supply unit 44 or the fuel gas supply unit 45. In such cases, there are errors in the gas supply amount of oxygen-containing gas or fuel gas supplied to the combustion unit, and the temperature of the power generation unit 40 is not the same, so the input voltage value to the converter 30 contained in each of the multiple fuel cell units 20 may vary among the multiple fuel cell units 20. As a result, the rate of deterioration in the fuel cell units 20 varies among the multiple fuel cell units 20, and if control is not taken to reduce the variation in the input voltage value to the converter 30 among the fuel cell units 20, the maintenance frequency of the fuel cell system 1 may increase compared to when control is taken to reduce the variation in the input voltage value to the converter 30 among the fuel cell units 20. Here, variation means, for example, when the difference between the maximum and minimum values ​​of the input voltage value to the converter 30 in the multiple fuel cell units 20 is not within a predetermined range. The predetermined range is a value appropriately set within 10% of the input voltage value to the converter 30 during rated power generation. Furthermore, if the input voltage value to the converter 30 varies among the multiple fuel cell units 20, the current value output from the converter 30 will also differ among the multiple fuel cell units 20. As a result, the fuel cell system 1 may be unable to supply the required current requested by the load group 2.

[0040] Therefore, the first control unit 13 controls the generated voltage value of the power generation unit 40 so that the input voltage value to each converter 30 of the multiple fuel cell units 20 is the same. Here, the generated voltage value is the value of the generated voltage of the power generation unit 40 detected by the voltage sensor 472. This reduces the variation in the input voltage value to the converter 30 included in each of the fuel cell units 20. For example, the first control unit 13 may control the current flowing through each of the multiple fuel cell units 20, the flow rate of oxygen-containing gas supplied to the fuel cell module 47, the flow rate of fuel gas supplied to the fuel cell module 47, and the flow rate of reformed water supplied to the fuel cell module 47 in order to control the generated voltage value of the power generation unit 40. For example, the first control unit 13 may perform at least one of the following controls to decrease the generated voltage value of the power generation unit 40: increasing the flow rate of oxygen-containing gas, decreasing the flow rate of fuel gas, and increasing the flow rate of reformed water. The first control unit 13 may, for example, perform at least one of the following controls to increase the generated voltage value of the power generation unit 40: decreasing the flow rate of oxygen-containing gas, increasing the flow rate of fuel gas, and decreasing the flow rate of reformed water. The first control unit 13 may, for example, control the input voltage value by decreasing the generated voltage value of some of the power generation units 40 while increasing the generated voltage value of the remaining power generation units 40 whose generated voltage value has not been decreased. The first control unit 13 may, for example, control the generated voltage value of the power generation unit 40 when the input voltage value to the converter 30 included in each of the multiple fuel cell units 20 varies for a predetermined time. The third control unit 33 may control the generated voltage value of the power generation unit 40 based on the control instructions of the first control unit 13. The third control unit 33 may control the oxygen-containing gas supply unit 44 based on the control instructions of the first control unit 13 to change the flow rate of oxygen-containing gas.

[0041] Here, the first control unit 13 controls the generated voltage value of the power generation unit 40 so as to change the current value flowing through each of the fuel cell units 20 according to the input voltage value to each of the converters 30 of the fuel cell units 20. Here, the current value is the current sensor This refers to the value of the current flowing through the fuel cell unit 20 as detected by the 50. For example, the fuel cell system 1 can decrease the generated voltage value of the power generation unit 40 by increasing the current value flowing through the fuel cell unit 20. Conversely, it can increase the generated voltage value of the power generation unit 40 by decreasing the current value flowing through the fuel cell unit 20. As a result, it is possible to reduce the variation in the input voltage values ​​to the converter 30 contained in each of the multiple fuel cell units 20.

[0042] Multiple fuel cell units 20 may include a first fuel cell unit containing a converter 30 that has the maximum input voltage value and a second fuel cell unit containing a converter 30 that has the minimum input voltage value.

[0043] Therefore, the first control unit 13 controls the power generation voltage value of the power generation unit 40 so that the difference between the input voltage value to the converter 30 included in the first fuel cell unit and the input voltage value to the converter 30 included in the second fuel cell unit is less than or equal to a predetermined threshold. This makes it possible to adjust the input voltage values ​​to the converter 30 included in each of the multiple fuel cell units 20 to be within a predetermined range, thereby reducing variations in the input voltage values ​​to the converter 30 included in each of the multiple fuel cell units 20. Here, the predetermined range is a value appropriately set within 10% of the input voltage value during rated power generation. The first control unit 13 calculates the difference between the input voltage value to the converter 30 included in the first fuel cell unit and the input voltage value to the converter 30 included in the second fuel cell unit from the input voltage value indicated by the input voltage value information. The first control unit 13 controls the power generation voltage value of the power generation unit 40 from when the difference exceeds a predetermined threshold until the difference falls below the predetermined threshold. The first control unit 13 may change the predetermined range, for example.

[0044] The first control unit 13 controls the generated voltage value of the power generation unit 40 to, for example, the amount of current requested by the load group 2. This allows the first control unit 13 to appropriately supply generated power to the load group 2. If the first control unit 13 changes the current value flowing to the fuel cell unit 20 when controlling the generated voltage value of the power generation unit 40 because the generated voltage value is fluctuating, it may adjust the current value flowing to the fuel cell unit 20 according to the amount of current requested.

[0045] Furthermore, the first control unit 13 controls the generated voltage value of the power generation unit 40 when, for example, the difference between the input voltage value to the converter 30 included in the first fuel cell unit and the input voltage value to the converter 30 included in the second fuel cell unit exceeds a predetermined threshold. This reduces the variation in the input voltage values ​​to the converters 30 included in each of the multiple fuel cell units 20 that exceeds a predetermined threshold.

[0046] When the input voltage values ​​to the converters 30 included in each of the multiple fuel cell units 20 vary, the first control unit 13 controls the generated voltage value of the power generation unit 40 so that the input voltage values ​​match the reference voltage value. Here, the reference voltage value is the target value of the input voltage value to the converters 30 included in each of the multiple fuel cell units 20.

[0047] First, the reference voltage value may be the input voltage value to the converter 30 included in the second fuel cell unit. The first control unit 13 controls the power generation voltage value of the power generation units 40 other than the power generation unit 40 included in the second fuel cell unit so that the input voltage value to the converter 30 of each of the multiple fuel cell units 20 becomes the input voltage value to the converter 30 included in the second fuel cell unit. This makes it possible to match the input voltage value to the converter 30 included in the fuel cell units 20 other than the second fuel cell unit to the input voltage value to the converter 30 included in the second fuel cell unit, thereby reducing variations in the input voltage values ​​to the converter 30 included in each of the multiple fuel cell units 20.

[0048] Next, the reference voltage value may be the input voltage value to the converter 30 included in the first fuel cell unit. The first control unit 13 controls the power generation voltage value of the power generation units 40 other than the power generation unit 40 included in the first fuel cell unit, for example, so that the input voltage value to the converter 30 of each of the multiple fuel cell units 20 becomes the input voltage value to the converter 30 included in the first fuel cell unit. As a result, the fuel cell system 1 can adjust the input voltage value to the converter 30 included in the fuel cell units 20 other than the first fuel cell unit to match the input voltage value to the converter 30 included in the first fuel cell unit, thereby reducing variations in the input voltage values ​​to the converter 30 included in each of the multiple fuel cell units 20.

[0049] Furthermore, the reference voltage value may be the average or median value of the input voltage values ​​to each converter 30 of the multiple fuel cell units 20. The first control unit 13 controls the generated voltage value of the power generation unit 40 included in the multiple fuel cell units 20 so that the input voltage value to each converter 30 of the multiple fuel cell units 20 becomes the average or median value of the input voltage values ​​to each converter 30 of the multiple fuel cell units 20. As a result, the fuel cell system 1 can adjust the input voltage value to each converter 30 included in the multiple fuel cell units 20 to the average or median value of the input voltage values ​​to each converter 30 of the multiple fuel cell units 20, thereby reducing variations in the input voltage values ​​to each converter 30 included in the multiple fuel cell units 20.

[0050] <Electrically connected series power generation units> As shown in Figure 1, when multiple power generation units 40 are electrically connected in series, the generated voltage may vary due to individual differences in the fuel cell modules 47 included in each of the multiple power generation units 40. As a result, if a high current flows through the power generation unit 40 with the lowest generated voltage, degradation may progress due to the increase in temperature of the power generation unit 40, and if a low current flows through the power generation unit 40 with the highest generated voltage, the power generation efficiency of the power generation unit 40 may decrease.

[0051] Therefore, the first control unit 13 controls the power generation voltage value of at least one of the multiple power generation units 40 so that the power generation voltage values ​​of each of the multiple power generation units 40 that are electrically connected in series are the same. This reduces the variation in the power generation voltage values ​​of the fuel cell modules 47 included in each of the multiple power generation units 40.

[0052] The temperature of the power generation unit 40 may rise due to a decrease in the flow rate of oxygen-containing gas supplied to the fuel cell module 47, an increase in the flow rate of fuel gas supplied to the fuel cell module 47, or a decrease in the flow rate of reformed water supplied to the fuel cell module 47. In such cases, if the temperature of the power generation unit 40 rises, the deterioration of the power generation unit 40 may progress rapidly. Therefore, if multiple power generation units 40 include a power generation unit 40 (hereinafter referred to as the first power generation unit) whose temperature, as acquired by the temperature sensor 471, is higher than a predetermined first temperature, the first control unit 13 controls, for example, the power generation voltage value of the first power generation unit so that it reaches a predetermined first temperature. This reduces the progression of deterioration of the first power generation unit.

[0053] Here, the first control unit 13 controls the power generation units 40 other than the first power generation unit so that their generated voltage values ​​become the generated voltage values ​​of the first power generation unit at a first temperature. Here, the generated voltage value of the first power generation unit at a first temperature is, for example, the measured value of the generated voltage value obtained by the voltage sensor 472 when the temperature obtained by the temperature sensor 471 is the first temperature. The generated voltage value of the first power generation unit at a first temperature may also be, for example, an estimated value of the generated voltage value obtained by the voltage sensor 472 when the temperature obtained by the temperature sensor 471 is the first temperature. As a result, the fuel cell unit 20 sets the generated voltage values ​​of the power generation units 40 other than the first power generation unit to match the generated voltage value of the first power generation unit. Because the values ​​can be matched, it is possible to reduce variations in the generated voltage values ​​of the fuel cell modules 47 included in each of the multiple power generation units 40.

[0054] Furthermore, the first control unit 13 controls the power generation voltage of the first power generation unit in such a way that it reduces the power generation voltage by performing at least one of the following control actions: increasing the flow rate of oxygen-containing gas, decreasing the flow rate of fuel gas, and increasing the flow rate of reformed water. This reduces the progression of deterioration of the first power generation unit.

[0055] The temperature of the power generation unit 40 may decrease due to an increase in the flow rate of oxygen-containing gas supplied to the fuel cell module 47, a decrease in the flow rate of fuel gas supplied to the fuel cell module 47, or an increase in the flow rate of reformed water supplied to the fuel cell module 47. In such cases, as the temperature of the power generation unit 40 decreases, the power generation unit 40 may misfire or its power generation efficiency may decrease. Therefore, if any of the multiple power generation units 40 include a second power generation unit whose temperature, as acquired by the temperature sensor 471, falls below a predetermined second temperature, the first control unit 13 controls, for example, the power generation voltage value of the second power generation unit so that it reaches the predetermined second temperature. This reduces the possibility of the second power generation unit misfiring or its power generation efficiency decreasing.

[0056] Here, the first control unit 13 controls the power generation voltage values ​​of the multiple power generation units 40 other than the second power generation unit so that they match the power generation voltage value of the second power generation unit at the second temperature. Here, the power generation voltage value of the second power generation unit at the second temperature is, for example, an estimated value of the power generation voltage value obtained by the voltage sensor 472 when the temperature obtained by the temperature sensor 471 is the second temperature. As a result, the power generation voltage values ​​of the multiple power generation units 40 other than the second power generation unit can be matched to the power generation voltage value of the second power generation unit, thereby reducing the variation in the power generation voltage values ​​of the fuel cell modules 47 included in each of the multiple power generation units 40.

[0057] Furthermore, the first control unit 13 controls the power generation voltage of the second power generation unit to increase the power generation voltage by performing at least one of the following controls: for example, reducing the flow rate of oxygen-containing gas, increasing the flow rate of fuel gas, and reducing the flow rate of reformed water. This reduces the possibility of the second power generation unit misfiring or a decrease in power generation efficiency.

[0058] When the first control unit 13 changes the flow rate of the oxygen-containing gas, it may control the flow rate of the fuel gas and the flow rate of the reformed water so as not to change them.

[0059] When the first control unit 13 changes the flow rate of the fuel gas, it may also control the flow rate of the oxygen-containing gas and the flow rate of the reformed water so as not to change them.

[0060] When the first control unit 13 changes the flow rate of the reformed water, it may also control the flow rates of the oxygen-containing gas and the fuel gas so as not to change them.

[0061] The third control unit 33 executes each control based on the control instructions from the first control unit 13. The third control unit 33 may also execute each control based on its own judgment depending on the status of the power generation unit 40. For example, if communication with the first control unit 13 is lost, the third control unit 33 may also execute each control based on its own judgment.

[0062] The first communication unit 11 receives input voltage value information, for example, indicating the input voltage value from the power generation unit 40 to the converter 30. The input voltage value to the converter 30 may vary among multiple fuel cell units 20, or the generated voltage value of the power generation unit 40 may vary among multiple power generation units 40. In such cases, the first control unit 13 creates a control signal to control the input voltage value. The first communication unit 11 transmits the control signal to the third communication unit 31. The control signal, for example, indicates that the input voltage value to the converter 30 of each of the multiple fuel cell units 20 is the same. This is a signal that instructs the system to behave in a certain way. The control signal may also be a signal that instructs the system to change the current value flowing through each of the multiple fuel cell units 20 according to the input voltage value to each of the converters 30 of the multiple fuel cell units 20. The control signal may also be a signal that instructs the system to control the system when the difference between the input voltage value to the converter 30 included in the first fuel cell unit and the input voltage value to the converter 30 included in the second fuel cell unit exceeds a predetermined threshold. The control signal may also be a signal that instructs the system to behave in a certain way, for example, so that the input voltage value to each of the converters 30 of the multiple fuel cell units 20 becomes the input voltage value to the converter 30 included in the second fuel cell unit. The control signal may also be a signal that instructs the system to behave in a certain way, for example, so that the input voltage value to each of the converters 30 of the multiple fuel cell units 20 becomes the input voltage value to the converter 30 included in the first fuel cell unit. The control signal may also be a signal that instructs the system to behave in a certain way, for example, so that the input voltage value to each of the converters 30 of the multiple fuel cell units 20 becomes the average or median value of the input voltage values ​​to each of the converters 30 of the multiple fuel cell units 20. The control signal may, for example, be a signal that instructs the difference between the input voltage value to the converter 30 included in the first fuel cell unit and the input voltage value to the converter 30 included in the second fuel cell unit to be less than or equal to a predetermined threshold. The control signal may, for example, be a signal that instructs the current amount to be the amount requested by the load group 2. The control signal may, for example, be a signal that instructs the generated voltage values ​​of each of the multiple power generation units 40 that are electrically connected in series to be the same. The control signal may, for example, be a signal that instructs the generated voltage values ​​of the first power generation unit and the second power generation unit to be the same. The control signal may, for example, be a signal that instructs the first power generation unit to reach a predetermined first temperature. The control signal may, for example, be a signal that instructs the first power generation unit to reach the generated voltage value at the first temperature. The control signal may, for example, be a signal that instructs the generated voltage value to decrease by performing at least one of the following controls: increasing the flow rate of oxygen-containing gas, decreasing the flow rate of fuel gas, and increasing the flow rate of reformed water. The control signal may, for example, be a signal that instructs the second power generation unit to reach a predetermined second temperature.The control signal may, for example, be a signal that instructs the second power generation unit to produce a voltage value equal to that of the second power generation unit at a second temperature. The control signal may also be a signal that instructs the unit to increase the voltage value by performing at least one of the following controls: decreasing the flow rate of oxygen-containing gas, increasing the flow rate of fuel gas, and decreasing the flow rate of reformed water.

[0063] (Processing related to the generated voltage value) As shown in Figure 4, in an example of an embodiment, the processing related to the generated voltage value when the temperature obtained by the temperature sensor 471 is 4th temperature or higher, which is performed by at least one of the first control unit 13, the second control unit 24, and the third control unit 43, will be explained using a flowchart.

[0064] In step S1, the first control unit 13 extracts the maximum input voltage value and the minimum input voltage value from the input voltage values ​​from the power generation unit 40 to the converter 30, which have been acquired as input voltage value information. After extraction, the first control unit 13 calculates the difference between the maximum input voltage value and the minimum input voltage value. After calculation, the first control unit 13 determines whether the difference is greater than or equal to a predetermined threshold. If the difference is greater than or equal to the predetermined threshold, the process proceeds to step S2. If the difference is not greater than or equal to the predetermined threshold, the processing related to the generated voltage value is terminated.

[0065] In step S2, the first control unit 13 determines whether the temperature obtained from each of the temperature sensors 471 of the multiple power generation units 40 included in the fuel cell unit 20 is above a predetermined fourth temperature. If the temperature obtained from the temperature sensors 471 is above the predetermined fourth temperature, the first control unit 13 performs temperature reduction control of the power generation unit 40. For example, as temperature reduction control of the power generation unit 40, the first control unit 13 directly controls the flow rate of oxygen-containing gas supplied from the oxygen-containing gas supply unit 44, or indirectly controls it so that either the second control unit 24 or the third control unit 43 performs the control. In the following expressions, when the first control unit 13 performs the control, it is referred to as direct control. The case where either the second control unit 24 or the third control unit 43 performs the action is described as indirect. After the control is complete, the process returns to step S1. If the temperature obtained from the temperature sensor 471 is not above a predetermined fourth temperature, the process proceeds to step S3 as control of the power generation unit 40 to the minimum voltage value or a similar value.

[0066] In step S3, the first control unit 13 determines whether the supply value of the oxygen-containing gas supply unit 44 is below a predetermined threshold. If the supply value is below the predetermined threshold, the process proceeds to step S4. If the supply value is not below the predetermined threshold, the flow rate of oxygen-containing gas supplied from the oxygen-containing gas supply unit 44 is reduced. The supply value can be selected and set from the number of pumps driven, the flow rate of oxygen-containing gas, the air utilization rate (Ua), the air-to-fuel gas ratio (A / F), etc. In the following description, the above supply value may be replaced with the respective values ​​in the description of the fuel gas supply unit 45 or the reformed water supply unit 46. After control, the process proceeds to step S6.

[0067] In step S4, the first control unit 13 determines whether the supply value from the fuel gas supply unit 45 is equal to or greater than a predetermined threshold. If the number of drives is equal to or greater than the predetermined threshold, the process proceeds to step S5. If the supply value is not equal to or greater than the predetermined threshold, the flow rate of fuel gas supplied from the fuel gas supply unit 45 is increased. After control, the process proceeds to step S6.

[0068] In step S5, the first control unit 13 determines whether the supply value from the reformed water supply unit 46 is below a predetermined threshold. If the supply value is below the predetermined threshold, the processing related to the power generation voltage value is terminated. If the supply value is not below the predetermined threshold, the flow rate of reformed water supplied from the reformed water supply unit 46 is reduced. After control, the process proceeds to step S6.

[0069] In step S6, the first control unit 13 determines whether the temperature obtained from each of the temperature sensors 471 of the multiple power generation units 40 included in the fuel cell unit 20 is above a predetermined first temperature. If the temperature obtained from the temperature sensors 471 is above the predetermined first temperature, the first control unit 40 controls the power generation units 40 other than the one that has reached the first temperature so that the generated voltage value of the other power generation units 40 becomes the same as the generated voltage value of the power generation unit 40 that has reached the first temperature. If the temperature obtained from the temperature sensors 471 is not above the predetermined first temperature, the process proceeds to step S7.

[0070] In step S7, the first control unit 13 determines whether the difference between the maximum input voltage value and the minimum input voltage value is greater than or equal to a predetermined threshold. If the difference is greater than or equal to the predetermined threshold, the process returns to step S2. If the difference is not greater than or equal to the predetermined threshold, the processing related to the generated voltage value is terminated.

[0071] [Example of change 1] As shown in Figure 5, the processing related to the generated voltage value when the combustion section temperature is below the third temperature, which is performed by the first control unit 13 in one example of the embodiment, will be explained using a flowchart.

[0072] In step S21, the first control unit 13 extracts the maximum input voltage value and the minimum input voltage value from the input voltage values ​​from the power generation unit 40 to the converter 30, which have been acquired as input voltage value information. After extraction, the first control unit 13 calculates the difference between the maximum input voltage value and the minimum input voltage value. After calculation, the first control unit 13 determines whether the difference is greater than or equal to a predetermined threshold. If the difference is greater than or equal to the predetermined threshold, the process proceeds to step S22. If the difference is not greater than or equal to the predetermined threshold, the processing related to the generated voltage value is terminated.

[0073] In step S22, the first control unit 13 determines whether the combustion chamber temperature is below a predetermined third temperature. If the combustion chamber temperature is below a predetermined first temperature, it directly or indirectly controls the increase in the combustion chamber temperature. For example, as a control for increasing the combustion chamber temperature, the first control unit 13 increases the flow rate of fuel gas supplied from the fuel gas supply unit 45. After the control, step S Return to step 21. If the combustion chamber temperature is not below a predetermined first temperature, proceed to step S23.

[0074] In step S23, the first control unit 13 determines whether the supply value from the oxygen-containing gas supply unit 44 is equal to or greater than a predetermined threshold. If the supply value is equal to or greater than the predetermined threshold, the process proceeds to step S24. If the supply value is not equal to or greater than the predetermined threshold, the flow rate of oxygen-containing gas supplied from the oxygen-containing gas supply unit 44 is increased. After the control, the process proceeds to step S26.

[0075] In step S24, the first control unit 13 determines whether the supply value from the reformed water supply unit 46 is equal to or greater than a predetermined threshold. If the supply value is equal to or greater than the predetermined threshold, the process proceeds to step S25. If the supply value is not equal to or greater than the predetermined threshold, the flow rate of reformed water supplied from the reformed water supply unit 46 is increased. After the control, the process proceeds to step S26.

[0076] In step S25, the first control unit 13 determines whether the supply value from the fuel gas supply unit 45 is equal to or greater than a predetermined threshold. If the supply value is equal to or greater than the predetermined threshold, the processing related to the power generation voltage value is terminated. If the supply value is not equal to or greater than the predetermined threshold, the flow rate of fuel gas supplied from the fuel gas supply unit 45 is reduced. After control, the process proceeds to step S26.

[0077] In step S26, the first control unit 13 determines whether the temperature obtained from each of the temperature sensors 471 of the multiple power generation units 40 included in the fuel cell unit 20 is below a predetermined second temperature. If the temperature obtained from the temperature sensors 471 is below the predetermined second temperature, the first control unit 40 controls the power generation units 40 other than the one whose temperature is below the second temperature so that the generated voltage value of the other power generation units 40 becomes the same as the generated voltage value of the power generation unit 40 whose temperature is below the second temperature. If the temperature obtained from the temperature sensors 471 is not below the predetermined second temperature, the process proceeds to step S27.

[0078] In step S27, the first control unit 13 determines whether the difference between the maximum input voltage value and the minimum input voltage value is greater than or equal to a predetermined threshold. If the difference is greater than or equal to the predetermined threshold, the process returns to step S22. If the difference is not greater than or equal to the predetermined threshold, the processing related to the generated voltage value is terminated.

[0079] In this disclosure, the designations "First," "Second," etc., are identifiers used to distinguish the configurations. Configurations distinguished by the designations "First," "Second," etc., in this disclosure may have their numbers swapped. For example, the first supply unit may swap the identifiers "First" and "Second" with the second supply unit. The swapping of identifiers occurs simultaneously. The configurations remain distinguishable even after the swapping of identifiers. Identifiers may be deleted. Configurations from which identifiers have been deleted are distinguished by their reference numerals. The designations "First," "Second," etc., in this disclosure should not be used solely to interpret the order of the configurations or to justify the existence of smaller numbered identifiers. While this disclosure has been described based on drawings and embodiments, it should be noted that those skilled in the art will find it easy to make various modifications or alterations based on this disclosure. Therefore, it should be noted that these modifications or alterations are within the scope of this disclosure. For example, the functions, etc., included in each functional unit can be rearranged in a logically consistent manner. Multiple functional units, etc., may be combined into one or separated. Each embodiment of the present disclosure described above is not limited to being implemented strictly according to the respective embodiment described, but can be implemented by combining features or omitting parts as appropriate. In other words, the contents of this disclosure can be modified and altered in various ways by those skilled in the art. Therefore, these modifications and alterations are included within the scope of this disclosure. For example, in each embodiment, each functional part, each means or each step can be added to or replaced with functional parts, each means or each step in other embodiments in a logically consistent manner. Also, in each embodiment, multiple functional parts, each means or each step can be combined into one or divided. Furthermore, each embodiment of the present disclosure described above is not limited to being implemented strictly according to the respective embodiment described, but can be implemented by combining features or omitting parts as appropriate. [Explanation of Symbols]

[0080] 1. Fuel cell system 2 load groups 3 Power Conversion Unit 10 Integrated Control Unit 11. First Communications Department 12 1st memory section 13. First Control Unit 20 Fuel Cell Units 21 Unit Integrated Control Unit 22. Second Communications Department 23 2nd memory section 24 Second Control Unit 30 Converters 40 Power Generation Section 41. Third Communications Department 42 Third memory section 43 Third Control Unit 44 Oxygen-containing gas supply unit 441 Oxygen-containing gas flow meter 45 Fuel Gas Supply Unit 451 Fuel gas flow meter 46. ​​Water Treatment Supply Department 461 Reformed water flow meter 47 Fuel cell module 471 Temperature Sensor 472 Voltage Sensor 50 Current Sensors

Claims

1. Multiple fuel cell units electrically connected in parallel, It comprises a control unit and, Each of the plurality of fuel cell units includes a converter and a power generation unit, A fuel cell system in which the control unit controls the power generation unit so that the input voltage value to the converter of each of the plurality of fuel cell units is the same.

2. The fuel cell system according to claim 1, wherein the control unit controls the power generation unit to change the current value flowing through each of the plurality of fuel cell units according to the input voltage value to the converter of each of the plurality of fuel cell units.

3. The plurality of fuel cell units include a first fuel cell unit that includes a converter to which the input voltage value is the maximum value and a second fuel cell unit that includes a converter to which the input voltage value is the minimum value. The fuel cell system according to claim 2, wherein the control unit controls the power generation unit when the difference between the input voltage value to the converter included in the first fuel cell unit and the input voltage value to the converter included in the second fuel cell unit is greater than or equal to a predetermined threshold.

4. The fuel cell system according to claim 3, wherein the control unit controls the power generation units other than the power generation unit included in the second fuel cell unit so that the input voltage value to the converter of each of the plurality of fuel cell units becomes the input voltage value to the converter included in the second fuel cell unit.

5. The fuel cell system according to claim 3, wherein the control unit controls the power generation units other than the power generation unit included in the first fuel cell unit so that the input voltage value to the converter of each of the plurality of fuel cell units becomes the input voltage value to the converter included in the first fuel cell unit.

6. The fuel cell system according to claim 3, wherein the control unit controls the plurality of fuel cell units such that the input voltage value to each of the plurality of fuel cell units' converters becomes the average or median value of the input voltage values ​​to each of the plurality of fuel cell units' converters.

7. The fuel cell system according to claim 3, wherein the control unit controls the power generation unit so that the difference between the input voltage value to the converter included in the first fuel cell unit and the input voltage value to the converter included in the second fuel cell unit is less than or equal to a predetermined threshold.

8. The fuel cell system according to claim 2, wherein the control unit controls the power generation unit so that the current amount is the amount requested from an external source.

9. The power generation unit includes a first power generation unit and a second power generation unit that are electrically connected in series. The fuel cell system according to claim 1, wherein the control unit controls at least one of the first and second power generation units so that the generated voltage values ​​of the first and second power generation units are the same.

10. The fuel cell system according to claim 9, wherein the control unit controls the first power generation unit so that the first power generation unit reaches a predetermined first temperature.

11. The control unit shall determine the generated voltage value of the first power generation unit at the first temperature. A fuel cell system according to claim 10, which controls a second power generation unit.

12. The power generation unit further comprises an oxygen-containing gas supply unit for supplying oxygen-containing gas, a fuel gas supply unit for supplying fuel gas, and a reformed water supply unit for supplying reformed water. The fuel cell system according to claim 10, wherein the control unit controls the first power generation unit to reduce the power generation voltage value by performing at least one of the following controls: increasing the flow rate of the oxygen-containing gas, decreasing the flow rate of the fuel gas, and increasing the flow rate of the reformed water.

13. The fuel cell system according to claim 9, wherein the control unit controls the second power generation unit so that the second power generation unit reaches a predetermined second temperature.

14. The fuel cell system according to claim 13, wherein the control unit controls the plurality of power generation units other than the second power generation unit so that the generated voltage value of the second power generation unit is the same as the generated voltage value of the second power generation unit at the second temperature.

15. The power generation unit further comprises an oxygen-containing gas supply unit for supplying oxygen-containing gas, a fuel gas supply unit for supplying fuel gas, and a reformed water supply unit for supplying reformed water. The fuel cell system according to claim 13, wherein the control unit controls the second power generation unit to increase the power generation voltage value by performing at least one of the following controls: reducing the flow rate of the oxygen-containing gas, increasing the flow rate of the fuel gas, and reducing the flow rate of the reformed water.

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