JP5156171B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system that generates power by supplying a fuel gas and an oxygen-containing gas to a fuel cell assembly including a plurality of fuel cells.

  In recent years, various types of fuel cell systems such as solid polymer type, phosphoric acid type, molten carbon salt type, and solid electrolyte type have been proposed as next-generation energy. In particular, although the solid oxide fuel cell system has an operating temperature as high as about 1000 ° C., it has advantages such as high power generation efficiency and use of exhaust heat, and research and development are being promoted.

A typical example of a fuel cell power generation system is a fuel including a housing defining a power generation / combustion chamber and a plurality of fuel cells disposed in the power generation / combustion chamber, as disclosed in Patent Document 1 below. A battery assembly is provided. The fuel cell assembly is provided with fuel gas supply means for supplying fuel gas to the fuel cell and oxygen-containing gas supply means for supplying oxygen-containing gas to the fuel cell. Usually, the fuel gas supply means includes a supply source of the reformed gas that may be city gas, a water supply source that may be clean water, a reformed gas supply amount adjusting means, a water supply amount adjusting means, and a reforming means. . An appropriate reforming catalyst is accommodated in the reforming means, and the to-be-reformed gas supplied together with water is reformed into hydrogen-rich fuel gas in the reforming means. The oxygen-containing gas supply means includes an oxygen-containing gas supply source that may be air and an oxygen-containing gas supply amount adjusting means. The fuel cell system further includes power generation control means for controlling power generation by controlling the fuel gas supply amount and the oxygen-containing gas supply amount in accordance with the required power amount.
JP 2000-149976 A

  As a mode of controlling the power generation according to the required power amount, the temperature in the power generation / combustion chamber is substantially constant in view of the fact that the amount of power generated by the fuel cell, that is, the current value and voltage value depends on the temperature in the power generation / combustion chamber. The fuel gas supply amount (that is, the reformed gas supply amount and the water supply amount) and the oxygen content so that the current value corresponds to the required power value on the basis of the current-voltage characteristics of the fuel cell. It can be intended to control the gas supply. However, when such a control mode is adopted, appropriate heating means such as a gas combustion type or an electric type for maintaining the temperature in the power generation / combustion chamber substantially constant is arranged separately from the fuel cell. The initial installation cost of the fuel cell system is considerably increased due to such heating means, and the operation cost is also increased.

  The present invention has been made in view of the above-mentioned facts, and the main technical problem thereof is that there is no heating means for maintaining the temperature in the power generation / combustion chamber substantially constant, and therefore the initial equipment cost and A new and improved fuel cell power generation system capable of controlling power generation by adequately controlling the fuel gas supply amount and the oxygen gas supply amount according to the required power value without increasing the operation cost. Is to provide.

  In the present invention, the provisional current value or provisional voltage value is calculated according to the required power value, and after setting the provisional current value or provisional voltage value, the effective power value sufficiently corresponds to the request power value. The main technical problem described above is achieved by adopting a so-called convergent required power follow-up method that determines whether or not to adequately increase or decrease the provisional current value when it is not sufficiently adequate.

That is, according to the present invention, a fuel cell assembly including a plurality of fuel cells, a fuel gas supply means including a fuel gas supply amount adjusting means for supplying fuel gas to the fuel cell assembly, In a fuel cell system comprising: an oxygen-containing gas supply means including an oxygen-containing gas supply amount adjusting means for supplying an oxygen-containing gas to a fuel cell assembly; and a power generation control means.
The power generation control means includes
(A) When the required power value fluctuates, a temporary current value or a temporary voltage value is calculated based on the required power value,
(B) The provisional current value and the effective current value or the provisional voltage value and the effective voltage value are compared, and when the provisional current value is smaller than the effective current value by an allowable error or the provisional voltage value is If the effective voltage value is smaller than the allowable error, the fuel gas supply amount adjusting means is adjusted based on the difference between the provisional current value and the effective current value or the difference between the provisional voltage value and the effective voltage value. When the fuel gas supply amount is reduced by control and the oxygen-containing gas supply amount adjusting means is controlled to set the oxygen-containing gas supply amount, and the provisional current value is larger than the effective current value and exceeds the allowable error Or when the provisional voltage value is larger than the effective voltage value exceeding an allowable error, based on the difference between the provisional current value and the effective current value or the difference between the provisional voltage value and the effective voltage value, The fuel gas supply amount adjusting means is controlled to increase the fuel gas supply amount and the oxygen Yu gas supply amount regulation means controlled by setting the oxygen-containing gas supply amount, the fuel gas supply amount regulation means and the fuel gas supply amount by controlling the oxygen-containing gas supply amount regulation means and an oxygen-containing gas supply amount When the changed effective power value is larger than the required power value by a predetermined value or more, the provisional current value or the provisional voltage value is decreased by a predetermined value, and the effective power value is smaller than the required power value by a predetermined value or more. In this case, it is means for repeating the step (b) of increasing the provisional current value or the provisional voltage value by a predetermined value. When the required power value is not more than a predetermined minimum power value, the required power value is reduced to the minimum value. A fuel cell system is provided, wherein the provisional current value or provisional voltage value is calculated as a power value.

Preferably , when the required power value is equal to or greater than a predetermined maximum power value, the provisional current value or the provisional voltage value is calculated using the request power value as the maximum power value.

  In the fuel cell system of the present invention, the provisional current value or provisional voltage value is calculated according to the required power value, and after setting the provisional current value or provisional voltage value, the effective power value is sufficiently appropriate for the required power value. It is determined whether or not it is compatible, and if it is not sufficiently appropriate, a so-called convergent required power tracking method is adopted to increase or decrease the provisional current value or provisional voltage value accordingly, thus generating and burning power The need to maintain the room temperature substantially constant is avoided, thus avoiding an increase in initial equipment costs and operating costs of the fuel cell system.

  Hereinafter, preferred embodiments of a fuel cell system configured according to the present invention will be described in detail with reference to the accompanying drawings.

  Referring to FIG. 2 together with FIG. 1, the fuel cell includes a fuel cell assembly 6, and the fuel cell assembly 6 includes a substantially rectangular parallelepiped housing 8. The housing 8 includes an outer frame body 10 formed from a heat-resistant metal plate and a heat insulating material layer 12 disposed on the inner surface of the outer frame body 10. The heat insulating material layer 12 can be formed from an appropriate ceramic. A partition wall 14 extending substantially horizontally is disposed at a lower portion of the housing 8, and the housing 8 includes a power generation / combustion chamber 16 above the partition wall 14 and an attached chamber 18 below the partition wall 14. It is airtightly partitioned. In the power generation / combustion chamber 16, three fuel cell stacks 20a, 20b and 20c are arranged in parallel. A fuel gas tank 21 is disposed in the attached chamber 18.

  2 and FIG. 3, each of the fuel cell stacks 20a, 20b and 20c extends in the vertical direction, that is, the vertical direction in FIG. 2 and the direction perpendicular to the paper surface in FIG. A plurality of solid oxide fuel cells 22 are arranged in the direction perpendicular to the paper surface in FIG. 2 and the vertical direction in FIG. 3 (five in the case of illustration). As clearly shown in FIG. 3, each of the fuel cells 22 includes an electrode support substrate 24, a fuel electrode layer 26 that is an inner electrode layer, a solid electrolyte layer 28, an oxygen electrode layer 30 that is an outer electrode layer, and an interconnector 32. It is configured. As can be understood from FIG. 2, each of the fuel cells 22 is made to stand upright on the partition wall 14 and extends somewhat above the middle portion in the vertical direction of the power generation / combustion chamber 16. The electrode support substrate 24 is a plate-like piece that is elongated in the vertical direction, and has both flat surfaces and both sides of a semicircular shape. A plurality (four in the illustrated example) of gas passages 34 are formed in the electrode support substrate 24 so as to penetrate the electrode support substrate 24 in the vertical direction. Each of the electrode support substrates 24 is bonded onto the partition wall 14 by, for example, a ceramic adhesive having excellent heat resistance. The partition wall 14 is formed with a plurality of slits (not shown) (not shown) extending in the left-right direction at intervals in the left-right direction and the direction perpendicular to the paper surface in FIG. A gas passage 34 formed in each electrode support substrate 24 is communicated with each slit. The upper wall of the fuel gas tank 21 disposed in the attached chamber 18 defined at the lower end of the housing 8 is defined by the partition wall 14, and therefore the interior of the fuel gas tank 21 is formed in the partition wall 14. The slits communicate with gas passages 34 formed in each of the electrode support substrates 24. The interconnector 32 is disposed on one surface of the electrode support substrate 24 (the upper surface in the fuel cell stack 20a in FIG. 3). The fuel electrode layer 26 is disposed on the other surface (the lower surface in the fuel cell stack 20a of FIG. 3) and both side surfaces of the electrode support substrate 24, and both ends thereof are joined to both ends of the interconnector 32. The solid electrolyte layer 28 is disposed so as to cover the entire fuel electrode layer 26, and both ends thereof are joined to both ends of the interconnector 32. The oxygen electrode layer 30 is disposed on the main portion of the solid electrolyte layer 28, that is, on the portion covering the other surface of the electrode support substrate 24, and is positioned facing the interconnector 32 with the electrode support substrate plate 24 interposed therebetween. It has been.

  A current collecting member 36 is disposed between adjacent fuel cells 22 in each of the cell stacks 20a, 20b, and 20c. The interconnector 32 of one fuel cell 22 and the oxygen electrode layer 30 of the other fuel cell 22 are arranged. Is connected. Current collecting members 36 are also arranged on both sides of each of the battery stacks 20a, 20b and 20c, that is, on one side and the other side of the fuel cell 22 located at the upper end and the lower end in FIG. The current collecting member 36 disposed at the lower end in FIG. 3 of the battery stacks 20a and 20b is connected by the conductive member 38, and the current collecting member 36 disposed at the upper end in FIG. 3 of the battery stacks 20b and 20c. Are also connected by a conductive member 38. Further, a terminal member 40 is connected to the current collecting member 36 disposed at the upper end in FIG. 3 of the battery stack 20a, and the terminal is also connected to the current collecting member 36 disposed at the lower end in FIG. 3 of the battery stack 20c. The member 40 is connected. Thus, all the fuel cells 22 are electrically connected in series, and the terminal members 40 exist at both ends of the series connection.

More specifically about the fuel cell 22, the electrode support substrate 24 is gas permeable to allow fuel gas to permeate to the fuel electrode layer 26, and is also conductive to collect current through the interconnector 32. It can be formed from a porous conductive ceramic (or cermet) that satisfies such a requirement. In order to manufacture the electrode support substrate 24 by simultaneous firing with the fuel electrode layer 26 and / or the solid electrolyte layer 28, it is preferable to form the electrode support substrate 24 from an iron group metal component and a specific rare earth oxide. In order to provide the required gas permeability, it is preferable that the open porosity is in the range of 30% or more, in particular 35 to 50%, and the conductivity is also 300 S / cm or more, in particular 440 C / cm or more. Is preferred. The fuel electrode layer 26 can be formed of a porous conductive ceramic, for example, ZrO ₂ (referred to as stabilized zirconia) in which a rare earth element is dissolved and Ni and / or NiO. The solid electrolyte layer 28 has a function as an electrolyte for bridging electrons between electrodes, and at the same time has a gas barrier property to prevent leakage between the fuel gas and the oxygen-containing gas. It is necessary and is usually formed from ZrO ₂ in which ₃ to 15 mol% of a rare earth element is dissolved. The oxygen electrode layer 30 can be formed of a conductive ceramic made of a so-called ABO ₃ type perovskite oxide. The oxygen electrode layer 30 is required to have gas permeability and preferably has an open porosity of 20% or more, particularly 30 to 50%. The interconnector 32 can be formed from a conductive ceramic, but it needs to have reduction resistance and oxidation resistance because it is in contact with a fuel gas that may be a hydrogen-rich gas and an oxygen-containing gas that may be air. For this purpose, lanthanum chromite-based perovskite oxides (LaCrO ₃ -based oxides) are preferably used. The interconnector 32 must be dense in order to prevent leakage of the fuel gas passing through the fuel passage 34 formed in the electrode support substrate 24 and the oxygen-containing gas flowing outside the electrode support substrate 24, and is 93% or more In particular, it is desirable to have a relative density of 95% or more. The current collecting member 36 can be composed of a member having an appropriate shape formed from an elastic metal or alloy, or a member obtained by adding a required surface treatment to a felt made of metal fiber or alloy fiber. The conductive member 38 and the terminal member 40 can be formed from an appropriate metal or alloy.

  1 and 2, the fuel cell system further includes a fuel gas supply means 42 for supplying fuel gas to the fuel cell assembly 6, and an oxygen-containing gas to the fuel cell assembly 6. Oxygen-containing gas supply means 44 for supply and exhaust gas discharge means 46 for discharging exhaust gas from the power generation / combustion chamber 16 defined in the housing 8 of the fuel cell assembly 6 are provided.

  The fuel gas supply means 42 includes a supply line 50 connected to a reformed gas supply source 48, which may be a city gas supply line or a propane gas cylinder. The supply line 50 includes a cutting valve 51 and a flow rate control means 52. Is arranged. The fuel gas supply means 42 also includes a reforming means 54 and a vaporizing means 56 disposed at the upper end of the power generation / combustion chamber 16 defined in the housing 8 of the fuel cell assembly 6 (in FIG. 2). The reforming means 54 and the vaporizing means 56 are simply shown in blocks). The reforming means 54 has a reforming chamber (not shown) containing a catalyst known per se necessary for reforming the gas to be reformed. The supply line 50 extends into the power generation / combustion chamber 16 and is connected to the inlet of the reforming means 54. The outlet of the reforming means 54 is connected to the fuel gas tank 21 through a communication path 58 and a connection pipe 59 formed in the side wall of the housing 8. On the downstream side of the flow rate control means 52, a blowing means 62 is connected to the supply line 50 via a cutoff valve 60. The fuel gas supply means 42 further includes a supply line 66 connected to a water supply source 64, which may be a clean water supply line. The supply line 66 includes a cutting valve 68, a water purification means 70, and a flow rate control means 72. It is arranged. The supply line 66 also extends into the power generation / combustion chamber 16 and is connected to the inlet of the vaporizing means 56. The outlet of the vaporizing means 56 is connected to the supply line 50 on the upstream side of the reforming means 54, and is thus connected to the reforming means 54 via the supply line 50. As will be further described later, a reformed gas, which may be city gas or propane gas, is supplied to the reforming means 54 through the supply line 50, and is reformed into hydrogen-rich fuel gas by the reforming means 54. Then, the gas is supplied to the fuel cell 22 and, more specifically, to the gas passage 34 formed in the electrode support substrate 24. As will be described later, the flow rate control means 52 and 72 constitute fuel gas supply amount adjusting means. The air blowing means 62 is operated as necessary, for example, at the time of start-up (more specifically, the temperature in the power generation / combustion chamber 16 partitioned in the housing 8 is sufficiently increased, and the vaporization means 56 is vaporized as required. Air is supplied to the reforming means 54). During normal operation of the fuel cell system 2 (that is, when the temperature in the power generation / combustion chamber 16 partitioned in the housing 8 is sufficiently raised and the vaporizing means 56 can perform the required vaporization) Water, which may be water, is supplied to the vaporizing means 56 after undergoing a required purification process by the water purifying means 70, steam is generated in the vaporizing means 56, and the steam is supplied to the reforming means 54.

  The oxygen-containing gas supply means 44 includes a supply line 74 that extends through a side wall of the housing 8 of the fuel cell assembly 6 to an oxygen-containing gas introduction pipe 72 that extends to the lower part of the power generation / combustion chamber 16. A blowing means 76 is disposed at the upstream end of the supply line 74. The supply line 74 is further provided with a flow rate control means 78 and a heat exchange means 80. As will be further described later, the flow rate control means 78 constitutes an oxygen-containing gas supply amount adjusting means. When the air blowing means 76 is operated, an oxygen-containing gas, which may be air, is caused to flow through the supply line 74, flows into the power generation / combustion chamber 8, and is supplied to the fuel cell 22.

  The description will be continued mainly with reference to FIG. 2 and FIG. 3. As will be further described later, for example, when the temperature in the power generation / combustion chamber 16 exceeds the required temperature by burning fuel gas in the power generation / combustion chamber 16, for example. Hydrogen-rich fuel gas is supplied from the fuel gas tank 21 to the gas passage 34 of the electrode support substrate 24 in the fuel cell 22 to ascend the gas passage 34, and the oxygen-containing gas is generated and burned through the oxygen-containing gas introduction pipe 72. Due to the introduction into the chamber 16, in each of the fuel cells 22, an electrode reaction of the following formula (1) is generated in the oxygen electrode layer 30, and the following formula (2) is generated in the fuel electrode layer 26. An electrode reaction is generated and power is generated. The generated electric power is taken out through the pair of terminal members 40.

Oxygen electrode: 1 / 2O ₂ + 2e ⁻ → O ²⁻ (solid electrolyte) (1)
Fuel electrode: O ²⁻ (solid electrolyte) + H ₂ → H ₂ O + 2e ⁻ (2)

  The fuel gas that has not been used for the electrode reaction of the fuel gas flowing through the gas passage 34 of the electrode support substrate 24 in the fuel cell 22 is caused to flow out into the power generation / combustion chamber 16 from the upper end of the electrode support substrate 24. It can be burned at the same time. Oxygen in the oxygen-containing gas introduced into the power generation / combustion chamber 16 through the oxygen-containing gas introduction pipe 72 is used for combustion. The inside of the power generation / combustion chamber 16 becomes a high temperature of, for example, about 1000 ° C. due to power generation in the fuel cell 22 and combustion of combustion gas.

  Referring to FIGS. 1 and 2, the exhaust gas discharge means 46 includes an exhaust gas outlet pipe 84 extending through the upper end of the side wall of the housing 8 and an exhaust line 86 extending from the exhaust gas outlet pipe 84. . A discharge line 86 extends through the heat exchange means 80. In the heat exchange means 80, the heat of the exhaust gas is conducted to the oxygen-containing gas supplied to the power generation / combustion chamber 16. The heat of the exhaust gas discharged through the discharge line 86 can be further used for heating water in a hot water supply system (not shown).

  FIG. 4 schematically illustrates the electrical components disposed in the fuel cell system. The fuel cell stacks 20a, 20b, and 20c are connected to, for example, a household power load in parallel with the commercial power supply system 96 via a boost chopper 90, an inverter 92, and a linkage relay 94. Between the commercial power supply system 96 and the load, a current converter 95 for measuring the amount of power supplied from the commercial power supply system 96 to the load is disposed. In the illustrated embodiment, a battery 102 is also connected to the fuel cell stacks 20a, 20b and 20c via a step-down chopper 98 and a charger 100. The battery 102 is connected to the inverter 92 via the boost chopper 103 and the boost chopper 90. In the fuel cell system, various AC drive devices and DC drive devices are arranged. In FIG. 4, for convenience of explanation, various AC drive devices are collectively indicated by numeral 104, and the various DC drive devices are collectively displayed. This is indicated by reference numeral 106. The DC drive device 106 is provided with a smoothing circuit 108. At the start of the fuel cell system, AC is directly supplied from the commercial power supply system 96 to the AC drive device 104, and AC from the storage battery 102 or from the commercial commercial power supply system 96 is supplied to the DC drive device 106 via the smoothing circuit 108. Supply. When power generation is started in the fuel cell stacks 20a, 20b, and 20c, the generated electricity is boosted by the boost chopper 90, converted into alternating current by the inverter 92, and supplied to the load via the linkage relay 94. When the power generation amount is insufficient with respect to the load, power is also supplied from the commercial power supply system 96 to the load. When the battery 102 is not sufficiently charged, at least a part of the generated electricity is stepped down by the step-down chopper 98 and supplied to the charger 100 to charge the battery 102. When the fuel cell stacks 20a, 20b and 20c are generating power, the DC drive device 106 is supplied with the generated electricity via the step-down chopper 98, and the AC drive device 104 is supplied with the generated electricity with the boost chopper 90 and Supply via an inverter 92. For example, when the commercial power supply system 96 goes out of power when the power generation system 2 is started up, the storage battery 102 is supplied with direct current from the storage battery 102 and the AC drive apparatus 104 is boosted. Alternating current is supplied through the chopper 103, the step-up chopper 90, and the inverter 92.

  In the fuel cell system configured according to the present invention, it is important that power generation control means for controlling the power generation of the fuel cell system by the convergent required power tracking method is provided. As shown schematically in FIG. 5, the power generation control means 110, which can be constituted by a microprocessor, is a fuel cell together with a required power value W during normal operation, and in the illustrated embodiment, required power due to household power load. The fuel gas supply amount and the oxygen-containing gas supply amount supplied to the fuel cell assembly 6 based on the required power value W determined by various AC drive devices 104 and various DC drive devices 106 in the system itself. Is used to control power generation.

  Continuing the description with reference to the flowchart shown in FIG. 6, in step n-1, it is determined whether or not the required power amount W1 has fluctuated. The initial required power value when the normal operation state is started and the power generation control is started can be set in advance. When the required power amount W1 fluctuates beyond a predetermined threshold value, the process proceeds to step n-2, and it is determined whether or not the required power value W1 is less than or equal to a preset maximum power value according to the power generation system capability. . If the required power value W1 is less than or equal to the maximum power value, the process proceeds to step n-3, and it is determined whether or not the required power value W1 is greater than or equal to a minimum power value set in advance according to the capacity of the power generation system. The When the required power value W1 is not more than the maximum power value and not less than the minimum power value, the process proceeds to step n-4 to calculate the provisional current I1. The provisional current I1 can be calculated, for example, by detecting the temperature in the power generation / combustion chamber 16 at the time of calculation and according to the current-voltage characteristics at the temperature. Alternatively, a predetermined calculation formula can be set in advance and the calculation can be performed based on the calculation formula. If the required power value W1 exceeds the maximum power value in step n-2, the process proceeds to step n-5, the required power value W1 is changed to the maximum power value, and the process proceeds to step n-4. If the required power value W1 is less than the minimum power value in step n-3, the process proceeds to step n-6, the required power value W1 is changed to the minimum power value, and the process proceeds to step n-4.

When the provisional current value I1 is calculated in step n-4, the process proceeds to step n-7.
In step n-7, it is determined whether or not the provisional current value I1 exceeds the current effective current value I2. When the provisional current value I1 is less than the effective current value I2, the process proceeds to step n-8, and the fuel gas supply amount is decreased according to the difference between the provisional current value I1 and the effective current value I2. Such reduction of the fuel gas supply amount can be achieved by operating the flow rate control means 52 to reduce the supply amount of the reformed gas and operating the flow rate control means 72 to reduce the supply amount of clean water. it can. If the provisional current value I1 exceeds the effective current value I2 in step n-7, the process proceeds to step n-9, and the fuel gas supply amount is set according to the difference between the provisional current value I1 and the effective current value I2. Increase . Such an increase in the fuel gas supply amount can be achieved by operating the flow rate control means 52 to increase the supply amount of the reformed gas and operating the flow rate control means 72 to increase the supply amount of clean water. it can. Progressing to step n-10 following step n-8 or n-9, the oxygen-containing gas supply amount is set to a required value. The oxygen-containing gas supply amount is set by calculating the oxygen-containing gas supply amount from a preset calculation formula based on the provisional current value I1, and operating the flow rate control means 78 to increase or decrease the oxygen-containing gas supply amount. This can be accomplished by letting it at least the required calculated value. If desired, the oxygen-containing gas supply amount can be set according to the difference between the provisional current value I1 and the effective current value I2, similarly to the setting of the fuel gas supply amount. Alternatively, the fuel gas supply amount can be set based on a calculated value obtained by calculating the fuel gas supply amount from a preset calculation formula based on the provisional current value I1.

Then, proceed to step n-11, to calculate the effective power value W2 on the basis of the effective current value I 2 and the effective voltage value. Thereafter, the routine proceeds to step n-12, where it is determined whether or not the difference between the effective power value W2 and the required power value W1 is less than a predetermined range α. When the difference between the effective power value W2 and the required power value W1 is less than the predetermined range α, the process returns to step n-1. If the difference between the effective power value W2 and the required power value W1 is greater than or equal to the predetermined range α, the process proceeds to step n-13, and whether or not the effective power value W2 is greater than the required power value W1 by the predetermined range α or not. Determined. When the effective power value W2 is greater than the required power value W1 by a predetermined range α or more, the process proceeds to step n-14, the provisional current value I1 is reduced by the predetermined value β, and the process returns to step n-7. The predetermined value β can be set in advance according to the characteristics of the fuel cell system. If the effective power value W2 is not larger than the required power value W1 by the predetermined range α or more in the step n-13, the process proceeds to step n-15 if the effective power value W2 is smaller than the required power value W1 by the predetermined range α or more. Then, the provisional current value I1 is increased by the predetermined value β, and the process returns to step n-7.

  In the embodiment described above, the provisional current value is calculated based on the required power value, and power generation is controlled by comparing the provisional current value with the effective current value. It is also possible to calculate the provisional voltage value and compare the provisional voltage value with the effective voltage value to control power generation.

1 is a block diagram schematically showing main components in a fuel cell system configured according to the present invention. FIG. 2 is a cross-sectional view schematically showing the fuel cell assembly in the fuel cell system of FIG. FIG. 3 is a cross-sectional view showing a fuel cell stack disposed in the fuel cell assembly of FIG. 2. FIG. 2 is a block diagram schematically illustrating electrical components in the fuel cell system of FIG. 1. FIG. 2 is a block diagram schematically illustrating a configuration related to power generation control in the fuel cell system of FIG. 1. The flowchart which shows the electric power generation control style in the fuel cell system of FIG.

Explanation of symbols

6: Fuel cell assembly 8: Housing 16: Power generation / combustion chambers 20a, 20b, 20c: Fuel cell stack 22: Fuel cell 42: Fuel gas supply means 44: Oxygen-containing gas supply means 48: Reformed gas supply source 52 : Flow rate control means (fuel gas supply amount adjustment means)
54: reforming means 56: vaporizing means 64: water supply source 72: flow rate control means (fuel gas supply amount adjusting means)
78: Flow rate control means (oxygen-containing gas supply amount adjustment means)
110: Power generation control means

Claims (2)

A fuel cell assembly including a plurality of fuel cells, a fuel gas supply means including a fuel gas supply amount adjusting means for supplying fuel gas to the fuel cell assembly, and an oxygen-containing gas in the fuel cell assembly In the fuel cell system, comprising: an oxygen-containing gas supply means including an oxygen-containing gas supply amount adjusting means, and a power generation control means.
The power generation control means includes
(A) When the required power value fluctuates, a temporary current value or a temporary voltage value is calculated based on the required power value,
(B) The provisional current value and the effective current value or the provisional voltage value and the effective voltage value are compared, and when the provisional current value is smaller than the effective current value by an allowable error or the provisional voltage value is If the effective voltage value is smaller than the allowable error, the fuel gas supply amount adjusting means is adjusted based on the difference between the provisional current value and the effective current value or the difference between the provisional voltage value and the effective voltage value. When the fuel gas supply amount is reduced by control and the oxygen-containing gas supply amount adjusting means is controlled to set the oxygen-containing gas supply amount, and the provisional current value is larger than the effective current value and exceeds the allowable error Or when the provisional voltage value is larger than the effective voltage value exceeding an allowable error, based on the difference between the provisional current value and the effective current value or the difference between the provisional voltage value and the effective voltage value, The fuel gas supply amount adjusting means is controlled to increase the fuel gas supply amount and the oxygen Yu gas supply amount regulation means controlled by setting the oxygen-containing gas supply amount, the fuel gas supply amount regulation means and the fuel gas supply amount by controlling the oxygen-containing gas supply amount regulation means and an oxygen-containing gas supply amount When the changed effective power value is larger than the required power value by a predetermined value or more, the provisional current value or the provisional voltage value is decreased by a predetermined value, and the effective power value is smaller than the required power value by a predetermined value or more. In this case, it is means for repeating the step (b) of increasing the provisional current value or the provisional voltage value by a predetermined value. When the required power value is not more than a predetermined minimum power value, the required power value is reduced to the minimum value. A fuel cell system, wherein the provisional current value or provisional voltage value is calculated as a power value.   2. The fuel cell system according to claim 1, wherein when the required power value is equal to or greater than a predetermined maximum power value, the provisional current value or the provisional voltage value is calculated using the request power value as the maximum power value.

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