JP5782371B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system.

  As a conventional fuel cell system, a fuel cell stack in which a plurality of fuel cells that generate power using a hydrogen-containing gas are connected in series, and both ends of the fuel cell stack in the series direction or between the fuel cells. One provided with two or more installed current collectors is known (for example, Patent Document 1). The generated power generated by such a fuel cell system is supplied to a PCS (Power Conditioning System) and also to auxiliary equipment such as a pump for supplying a hydrogen-containing gas and an oxygen-containing gas to be supplied to the fuel cell stack. Supplied.

JP 2003-308863 A

  Here, in the conventional technology as described above, at least a part of the fuel cell stack may be deteriorated due to, for example, non-uniformity in the flow of the hydrogen-containing gas in the fuel cell stack or a change in pressure loss. Yes, the voltage may decrease in the fuel cell stack.

  Therefore, an object of the present invention is to provide a fuel cell system that can reduce the power generation load of the stack portion where the voltage drop has occurred.

  In order to solve the above problems, a fuel cell system according to the present invention includes a plurality of stack units in which fuel cells are connected in series, a voltage detection unit that detects voltages of each of the plurality of stack units, and a plurality of stacks. A circuit unit that electrically connects the units to each other, and a relay unit that is provided in the circuit unit and switches a connection state between the stack unit and the circuit unit according to the voltage detected by the voltage detection unit. Features.

  In this fuel cell system, the connection state between the stack unit and the circuit unit is switched by the relay unit according to the voltage detected by the voltage detection unit. Therefore, for example, when a voltage drop occurs in at least a part of the plurality of stack parts, it is possible to appropriately switch the circuit part in the relay part and reduce the power generation load on the stack part in which the voltage drop has occurred.

  Moreover, it is preferable that the circuit unit connects at least a part of the plurality of stack units in series. Moreover, it is preferable that the circuit unit connects at least a part of the plurality of stack units in parallel.

  Moreover, it is preferable that a relay part switches this circuit part so that the electric power supply from the stack part by which the voltage drop was detected by the voltage detection means among several stack parts may be interrupted | blocked. In this case, it is possible to reliably reduce the power generation load on the stack portion where the voltage drop has occurred and suppress the voltage drop.

  In some cases, the apparatus further includes one or more auxiliary machines that are operated by the generated power output from the stack unit. The relay unit switches the wiring circuit unit so that the voltage of the generated power output from the stack unit is maintained at a predetermined voltage, and the predetermined voltage may be 5V, 12V, 24V, or 48V.

  According to the present invention, it is possible to reduce the power generation load of the stack portion where the voltage drop has occurred. As a result, the life of the fuel cell system can be extended. Further, by selecting and connecting a stack having a stable voltage to an auxiliary machine that operates with electric power generated by the fuel cell system itself, a decrease in the voltage applied to the auxiliary machine can be suppressed.

It is a block diagram which shows a fuel cell system. 1 is a block diagram showing a part of a fuel cell system according to a first embodiment. 1 is a perspective view showing a polymer electrolyte fuel cell stack according to a first embodiment. It is sectional drawing along the IV-IV line of FIG. It is a block diagram which shows a part of fuel cell system which concerns on 2nd Embodiment. It is a perspective view which shows the polymer electrolyte fuel cell stack which concerns on 2nd Embodiment. It is another block diagram which shows a part of fuel cell system which concerns on 2nd Embodiment. It is a block diagram which shows a part of fuel cell system which concerns on 3rd Embodiment. It is a block diagram which shows a part of fuel cell system which concerns on 4th Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted.

  FIG. 1 is a block diagram showing a fuel cell system. As shown in FIG. 1, the fuel cell system 1 includes a fuel supply device 10, a reformed water supply device 20, an oxygen-containing gas supply device 30, a hydrogen production unit 40, a cathode gas supply device 50, a fuel cell unit 60, a PCS 70, A voltage detection unit 80 and a system control unit 90 are provided.

  The fuel cell unit 60 includes a plurality of fuel cell stacks. The fuel cell unit 60 includes hydrogen in a hydrogen-containing gas as an anode gas at an anode electrode (not shown) of a fuel cell constituting the fuel cell stack, and oxygen as a cathode gas at a cathode electrode (not shown). Oxygen in the gas is supplied to generate electric power by causing movement of ions in an electrolyte body (not shown).

  The fuel supply device 10 is for supplying a raw material to be processed in a hydrogen production unit 40 described later. Examples of the raw material include compounds containing carbon and hydrogen (for example, hydrocarbons such as methane and propane, alcohols such as methanol and ethanol, ethers such as dimethyl ether, etc.). Among these, methanol, ethanol, dimethyl ether, methane, natural gas, city gas, LPG (liquefied petroleum gas), gasoline, naphtha, kerosene, light oil and the like are preferable from the viewpoint of availability.

  The reforming water supply device 20 is for supplying reforming water necessary for fuel processing in the hydrogen production unit 40. The oxygen-containing gas supply device 30 is for supplying an oxygen-containing gas necessary for fuel processing in the hydrogen production unit 40. Examples of the oxygen-containing gas include pure oxygen gas, oxygen-enriched air, and air. Of these, air is preferable from the viewpoint of ease of handling and cost.

  The hydrogen production unit 40 processes the raw material supplied from the raw material supply apparatus 10 to generate a hydrogen-containing gas. The generated hydrogen-containing gas is supplied to the anode of the fuel cell unit 60. Specifically, the hydrogen production unit 40 includes a reforming catalyst (not shown), includes fuel supplied from the fuel supply device 10, reformed water supplied from the reforming water supply device 20, and oxygen-containing content. A hydrogen-containing gas is generated using the oxygen-containing gas supplied from the gas supply device 30. As a reforming technique for producing hydrogen, a known technique can be applied. For example, a combination of a steam reforming reaction unit, a shift reaction unit, and a selective oxidation reaction unit can be used. Alternatively, a partial oxidation reaction unit, a steam reforming reaction unit, an autothermal reforming reaction unit, or a combination thereof may be used.

  The reforming catalyst contained in the hydrogen production unit 40 includes a carrier and a metal supported on the carrier. Examples of the constituent material of the carrier include aluminum oxide (alumina) and zirconium dioxide (zirconia). Examples of the supported metal include nickel, ruthenium, rhodium, iridium, palladium, platinum, rhenium, and cobalt.

  For example, when a fuel that does not require hydrogen generation processing such as pure hydrogen gas is supplied from the fuel supply device 10, the reforming water supply device 20, the oxygen-containing gas supply device 30, and the hydrogen production unit 40 are omitted. Can do. In that case, fuel can be directly supplied to the anode electrode of the fuel cell.

  The cathode gas supply device 50 is for supplying a cathode gas necessary for power generation to the cathode electrode of the fuel cell. Examples of the cathode gas include pure oxygen gas, oxygen-enriched air, and air. Of these, air is preferable from the viewpoint of ease of handling and cost.

  The PCS 70 plays a role as an electric power adjustment unit that adjusts electric power generated in the fuel cell unit 60, and includes a voltage converter 71 and an orthogonal converter 72. The voltage converter 71 converts the voltage of the DC power output from the fuel cell unit 60. For example, a DC / DC converter is cited. The orthogonal transformer 72 converts the power transformed by the voltage converter 71 from direct current to alternating current, and includes, for example, a DC / AC inverter.

  The voltage detection unit 80 measures the power generation voltage of the fuel cell stack units 101A, 101B, and 101C. The system control unit 90 has a drive control function for controlling the drive of the fuel cell system 1. Examples of the system control unit 90 include a device that performs electronic control (for example, a device that includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an input / output interface). . The system control unit 90 in this embodiment is electrically connected to an auxiliary machine represented by the fuel supply device 10, the reforming water supply device 20, the oxygen-containing gas supply device 30, the cathode gas supply device 50, and the like, and the PCS 70. Then, the auxiliary machine is controlled.

  The fuel supply device 10, the reforming water supply device 20, the oxygen-containing gas supply device 30, the cathode gas supply device 50, and the auxiliary equipment represented by the voltage detection unit 80 use the generated power of the fuel cell unit 60. It is a device that can operate. Here, from the viewpoint of suppressing the reduction in efficiency, power is supplied from between the fuel cell unit 60 and the voltage converter 71, and each auxiliary machine has power generation output from the fuel cell unit 60. A voltage converter (for example, a DC / DC converter) for transforming electric power is incorporated. The external power load EI consumes power supplied from the fuel cell system 1, and is, for example, a household power consuming device. The external power load EI is electrically connected to the fuel cell system 1 and the external power system CE.

  Next, an example of the operation of the fuel cell system 1 according to this embodiment will be described. First, each auxiliary machine is operated by the power from the external power system CE, and the fuel cell system 1 is started. At this time, power from the external power system CE is supplied from AC to DC by an AC / DC converter (not shown) and then supplied to each auxiliary machine.

  Specifically, when the auxiliary machines are operated by the electric power from the external power system CE, the hydrogen production unit 40 is supplied with fuel, the fuel supply device 10, the reforming water supply device 20, and the oxygen-containing gas supply device 30. Reformed water and oxygen-containing gas are supplied and reformed to generate hydrogen-containing gas (hereinafter, reformed gas). The generated reformed gas is supplied to the anode electrode of the fuel cell unit 60, and oxygen-containing gas (air) is supplied from the cathode gas supply device 50 to the cathode electrode of the fuel cell unit 60, and power generation is started. When power generation by the fuel cell system 1 is started, the operating power of the auxiliary machinery is switched from the external power system CE to the power generated by the fuel cell system 1 itself.

[First Embodiment]
FIG. 2 is a block diagram showing a part of the fuel cell system 1 in the first embodiment. In the present embodiment, the first to third stack units 101A to 101C, the PCS 70, the auxiliary machine 5, the voltage detection unit 80 that detects the voltages of the first to third stack units 101A to 101C, and the first to third components. Relay units 3a to 3d that can switch connection between the stack units 101A to 101C, the auxiliary machine 5, and the PCS 70 are provided, and a circuit (circuit unit) 4 is formed by them. FIG. 2A shows a relay unit 3a when no voltage drop is detected in the first to third stack units 101A to 101C and power to the auxiliary machine 5 is supplied from the second stack unit 101B. The connection state of 3d is shown. FIG. 2B illustrates the connection of the relay units 3a to 3d when the voltage of the second stack unit is lowered and the power supply to the auxiliary machine 5 is changed from the second stack unit 101B to the first stack unit 101A. Indicates the state.

  FIG. 3 is a perspective view showing an example of a fuel cell unit when a solid oxide fuel cell is used in the embodiment of FIG. 2, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. . As shown in FIG. 3, the fuel cell unit 60 </ b> A in the present embodiment includes a plurality of fuel cell stack portions 101, first to fourth current collectors 102 </ b> A to 102 </ b> D, and a cell fixing portion 103.

  As shown in FIG. 4, the fuel cell (single cell) 100 includes a membrane electrode assembly (hereinafter referred to as “MEA”) 110, an anode separator 120, and a cathode separator 130. . The MEA 110 includes an electrolyte membrane 111, an anode 112, and a cathode 113.

  The electrolyte membrane 111 is sandwiched between a pair of electrodes (anode 112 and cathode 113), and is formed of a polymer electrolyte membrane that selectively transmits hydrogen ions. As the polymer electrolyte membrane, for example, perfluorocarbon sulfonic acid can be used.

  The anode 112 is an electrode layer in a state where an electrochemical oxidation reaction occurs, and the cathode 113 is an electrode layer in a state where an electrochemical reduction reaction occurs. The anode 112 and the cathode 113 include a catalyst layer formed on the surface side of the electrolyte membrane 111 and a gas diffusion layer disposed on the outer surface of the catalyst layer. The catalyst layer is mainly composed of carbon powder carrying a platinum group metal catalyst. The gas diffusion layer has air permeability and electrical conductivity.

  The anode-side separator 120 is formed of a conductive carbon plate, and a gas flow path 122 through which a hydrogen-containing gas passes is formed by a plurality of grooves 121. The groove part 121 is formed in the contact surface 120b with the anode 112 of MEA110. Accordingly, the hydrogen-containing gas that passes through the gas flow path 122 is supplied to the anode 112.

  The cathode-side separator 130 is formed of a conductive carbon plate, and a gas flow path 132 through which an oxygen-containing gas passes is formed by the plurality of grooves 131. The groove 131 is formed in the contact surface 130b with the cathode 113 of the MEA 110. Therefore, the oxygen-containing gas that passes through the gas flow path 132 is supplied to the cathode 113.

  The fuel cell 100 generates electric power using hydrogen in the hydrogen-containing gas as the anode gas and oxygen in the oxygen-containing gas as the cathode gas. Examples of the hydrogen-containing gas include the above-described reformed gas. Examples of the oxygen-containing gas include pure oxygen gas, oxygen-enriched air, and air. Of these, air is preferable from the viewpoint of ease of handling and cost. In the present embodiment, the reformed gas is supplied from the hydrogen production unit 40 as the anode gas, and air is supplied as the cathode gas via a cathode gas supply device 50 described later.

  As shown in FIG. 2, the fuel cell stack unit 101 includes a plurality of fuel cells 100 connected in series, the first current collector 102 </ b> A disposed at one end in the series connection direction, and the other end in the stacking direction. The second current collector 102B is disposed in the part. The first and second current collectors 102 </ b> A and 102 </ b> B are formed of, for example, a copper plate and are electrically connected to the adjacent fuel cell 100. In addition, the first and second current collectors 102A and 102B are provided with connection terminals 102t extending outward to constitute the circuit 4A.

  The third current collector 102C is disposed between the first current collector 102A and the second current collector 102B in the series connection direction of the fuel cells 100. The third current collector 102C is constituted by, for example, the above-described separators 120 and 130, and is electrically connected to the adjacent fuel cell 100. The fourth current collector 102D is disposed between the second current collector 102B and the third current collector 102C in the series connection direction of the fuel cells 100. For example, the fourth current collector 102D includes the separators 120 and 130 described above, and is electrically connected to the adjacent fuel cell 100. Further, the third and fourth current collectors 102C and 102D are provided with connection terminals 102t projecting outward to constitute the circuit 4A.

  The third and fourth current collectors 102C and 102D are arranged such that the voltage between them is smaller than the voltage between the first and second current collectors 102A and 102B. Here, the first to fourth current collectors 102A to 102D are arranged at equal intervals in the series contact direction. Therefore, the power generation voltage by the fuel cell stack unit 101 between the first and third current collectors 102A and 102C, the power generation voltage by the fuel cell stack unit 101 between the second and fourth current collectors 102B and 102D, The voltage generated by the fuel battery cell 100 between the bodies 102A and 102C is a voltage for operating the auxiliary machine 5 (auxiliary machine operating voltage, for example, 24V).

  The fuel cell unit 60A configured as described above has a configuration in which the inside is divided and a plurality of stack portions 101A to 101C each functioning as an independent battery are connected in series. That is, the fuel cell 100 between the current collectors 102A and 102C constitutes the first stack portion 101A, and the fuel cell 100 between the current collectors 102C and 102D constitutes the second stack portion 101B, and the current collector 102D. , 102B constitute the third stack portion 101C.

  The cell fixing portion 103 is disposed outside each of the first and second current collectors 102 </ b> A disposed at both ends in the stacking direction of the fuel cells 100. The cell fixing unit 103 sandwiches the first and second current collectors 102A and 102B and fixes them from both sides.

  The relay units 3 a to 3 d have a configuration in which the first to third stack units 101 </ b> A to 101 </ b> C that supply power to the auxiliary machine 5 can be switched. The relay unit 3 (3a to 3d) includes a switch element. By controlling the ON / OFF of the switch element, the relay unit 3 (3a to 3d) is operated in accordance with the voltage of the generated power output from the fuel cell stack units 101A to 101C. The connection state between the first to third stack units 101A to 101C and the circuit 4 is switched. Here, the relay unit 3 switches the circuit 4 </ b> A based on the voltages of the first to third stack units 101 </ b> A to 101 </ b> C detected by the voltage detector 80 and maintains the voltage of the generated power supplied to the auxiliary machine 5. (Details will be described later). For example, a relay or the like is used as the relay unit 3.

  Here, at a normal time when the voltage drop of the first to third stack units 101A to 101C is not detected by the voltage detection unit 80, the relay units 3b and 3c are in the ON state, and the relay units 3a and 3d are in the OFF state. As a result, the circuit 4A is brought into the circuit state shown in FIG. At this time, the generated power generated in the first to third stack units 101A to 101C is supplied to the PCS 70, transformed by the voltage converter 71, converted from direct current to alternating current by the orthogonal transformer 72, and external power It is supplied to the load EI and consumed. At the same time, the 24V generated power generated in the second stack unit 101B is supplied to the auxiliary machine 5 to operate the auxiliary machine 5.

  On the other hand, for example, when the voltage drop of the second stack unit 101B is detected by the voltage detection unit 80, the relay units 3a and 3b are controlled to be in the ON state, 3c and 3d are in the OFF state, and the circuit 4A is For example, the circuit state shown in FIG. That is, the circuit 4A is switched so that the second stack unit 101B in which the voltage drop is detected by the voltage detection unit 80 is disconnected from the circuit 4A. In other words, the circuit 4A is switched so as to be connected to the stack unit 101 where the voltage is stable. As a result, the voltage of the generated power applied to the auxiliary machine 5 is maintained at 24V, and the decrease in the applied voltage is suppressed in the auxiliary machine 5.

  As described above, in this embodiment, for example, even when a voltage drop occurs in any of the first to third stack units 101A to 101C (a plurality of fuel cell stack units 101), the voltage value detected by the voltage detection unit 80 is set. Based on switching of the circuit 4A by the relay units 3a to 3d, the first to third stack units 101A to 101C for supplying power to the auxiliary machine 5 are switched, and the voltage of the generated power applied to the auxiliary machine 5 is set to a predetermined voltage. Can be maintained. As a result, it is possible to suppress a decrease in the voltage applied to the auxiliary machine 5 while reducing the power generation load on the fuel cell stack unit 101 where the voltage drop has occurred.

  Further, as described above, the relay units 3a to 3d are connected to the PCS 70 or / and the auxiliary machine from the second stack unit 101B in which the voltage detection is detected by the voltage detection unit 80 among the first to third stack units 101A to 101C. The circuit 4 </ b> A is switched to cut off the power supply to 5. Therefore, it is possible to reliably reduce the power generation load on the second stack unit 101B in which the voltage drop has occurred and suppress the voltage drop.

  Although the present embodiment includes three first to third stack parts 101A to 101C connected in series, the present invention is not limited to the number of stack parts, and a plurality of stack parts are provided. It only has to have. For example, a fourth stack unit 101D similar to the first to third stack units 101A to 101C may be further provided, and the first to fourth stack units 101A to 101D may be configured to be connected in series. Also in this case, the relay unit 3a to 3d is provided in the circuit 4A, and the relay unit 3a to 3d allows the connection between the fuel cell unit 60A and the circuit 4A according to the voltage of the generated power supplied to the auxiliary machine 5. The connection status is switched.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the description of the present embodiment, differences from the first embodiment will be mainly described.

  FIG. 5 is a block diagram showing a part of the fuel cell system according to the second embodiment. The fuel cell system of the present embodiment includes first to third stack units 201A to 201C, PCS 70, auxiliary machine 5, voltage detection unit 80 that detects voltages of first to third stack units 201A to 201C, and first 1 to 3rd stack parts 201A-201C are provided with the relay parts 3a-3d which can switch the connection of the auxiliary machine 5 and PCS70, and the circuit 4 is formed by them. In FIG. 3A, the voltage drop is not detected in the first to third stack parts 201A to 201C, and the power to the auxiliary machine 5 is supplied from the second stack part 201B. The connection state of is shown. FIG. 3B shows a connection state of the relay unit 3 when the voltage of the second stack unit 201B decreases and the power supply to the auxiliary machine 5 is changed to the first stack unit 201A.

  As shown in FIG. 5, the fuel cell system of the present embodiment is different from the first embodiment in that a fuel cell unit 60B is provided instead of the fuel cell unit 60A (see FIG. 2), and a circuit 4A (see FIG. 2). ) Instead of the circuit 4B.

  The fuel cell unit 60B of the present embodiment includes first to third stack parts 201A to 201C connected in parallel by a circuit 4B. Specifically, as shown in FIG. 6, the fuel cell unit 60 </ b> B is formed in the orthogonal direction of the stacking direction (the vertical direction in the figure: hereinafter simply referred to as “orthogonal direction”) by forming the insulating portions 205 and 206. The first to third stack parts 201A to 201C are divided into three.

  The insulating part 205 and the insulating part 206 are arranged so that the fuel cell unit 60B is equally divided into three in the orthogonal direction. Each of the first to third stack parts 201A to 201C is electrically insulated from each other and functions as an independent battery.

  Returning to FIG. 7, the circuit 4 </ b> B electrically connects the first to third stack parts 201 </ b> A to 201 </ b> C and connects them in series. The relay units 3 a to 3 f provided in the circuit 4 </ b> B have a configuration in which the first to third stack units 201 </ b> A to 201 </ b> C that supply power to the auxiliary machine 5 by the auxiliary machine 5 and the PCS 70 can be switched. .

  Here, at the normal time when the voltage drop of the first to third stack parts 201A to 201C is not detected by the voltage detection part 80, all the relay parts 3a to 3f are controlled to be in the ON state, and the circuit 4B is shown in FIG. The circuit state shown in FIG. At this time, the generated power generated in the first to third stack portions 201A to 201C is supplied to the PCS 70, transformed by the voltage converter 71, converted from direct current to alternating current by the orthogonal transformer 72, and external power It is supplied to the load EI and consumed. At the same time, the 24V generated power generated in the first to third stack parts 201A to 201C is supplied to the auxiliary machine 5 to operate the auxiliary machine 5.

  On the other hand, for example, when the voltage drop of the second stack unit 201B is detected by the voltage detection unit 80, the relay units 3a and 3b are controlled to be in the ON state, 3c and 3d are in the OFF state, and the circuit 4B is controlled. The circuit state shown in FIG. That is, the circuit 4B is switched so that the second stack unit 201B in which the voltage drop is detected by the voltage detection unit 80 is disconnected from the circuit 4B. As a result, the voltage of the generated power supplied to the auxiliary machine 5 is maintained at 24V, and the decrease in the applied voltage is suppressed in the auxiliary machine 5.

  Also in the present embodiment configured as described above, the first to first power supplies the auxiliary machine 5 by switching the circuit 4B by the relay units 3a to 3f based on the voltage value detected by the voltage detection unit 80. The three stack units 201A to 201C can be switched to maintain the voltage of the generated power supplied to the auxiliary machine 5 and the PCS 70 at a predetermined voltage. As a result, the power generation load on the fuel cell stack unit in which the voltage drop has occurred is reduced. However, it is possible to suppress a decrease in the voltage applied to the auxiliary machine 5.

  Moreover, in 2nd Embodiment, another operation can also be performed about the relay parts 3a-3f. FIG. 7 is another block diagram showing a part of the fuel cell system according to the second embodiment. As shown in FIG. 7, the fuel cell unit 60B in the present embodiment is configured by first to third stack portions 201A to 201C being electrically connected in parallel to each other. FIG. 7A shows a case where no voltage drop is detected in the first to third stack parts 201A to 201C, and power to the auxiliary machine 5 is supplied from the first to third stack parts 201A to 201C. The connection state of the relay units 3d to 3f is shown. FIG. 7B shows the connection of the relay units 3d to 3f when the voltage of the second stack unit 201B decreases and the power supply to the auxiliary machine 5 is changed to the first stack unit 201A and the third stack unit 201C. Indicates the state.

  Here, at the normal time when the voltage drop of the first to third stack parts 201A to 201C is not detected by the voltage detection part 80, the relay parts 3b, 3d, 3e and 3f are in the ON state, and the relay parts 3a and 3c are in the OFF state. Thus, the circuit 4B is brought into the circuit state shown in FIG. At this time, the generated power generated in the first to third stack portions 201A to 201C is supplied to the PCS 70, transformed by the voltage converter 71, converted from direct current to alternating current by the orthogonal transformer 72, and external power It is supplied to the load EI and consumed. At the same time, the 24V generated power generated in the first to third stack parts 201A to 201C is supplied to the auxiliary machine 5 to operate the auxiliary machine 5.

  On the other hand, for example, when a voltage drop in the second stack unit 201B is detected by the voltage detection unit 80, the relay units 3a, 3d, 3e, and 3f are in the ON state, and the relay units 3b and 3c are in the OFF state. Thus, the circuit 4B is brought into the circuit state shown in FIG. That is, the circuit 4B is switched so that the second stack unit 201B in which the voltage drop is detected by the voltage detection unit 80 is disconnected from the circuit 4B. As a result, the voltage of the generated power applied to the auxiliary machine 5 is maintained at 24V, and the decrease in the applied voltage is suppressed in the auxiliary machine 5.

  In addition, although 1st and 2nd embodiment is provided with the three 1st-3rd stack parts 201A-201C connected in parallel, as above-mentioned, this invention does not limit the number of stack parts. It is only necessary to have a plurality of stack parts.

  For example, the fuel cell unit 60B may further include a fourth stack part similar to the first to third stack parts 201A to 201C, and the first to fourth stack parts may be connected in parallel. Also in this case, the relay unit 3 is provided in the circuit 4B, and the first to fourth stack units and the circuit 4B are provided by the relay unit 3 according to the voltage of the generated power supplied to the auxiliary machine 5 and the PCS 70. The connection state with is switched.

  Further, as in the fuel cell system according to the third embodiment shown in FIG. 8, a circuit 4C is used by using a fuel cell unit 60C in which the first to fourth stack portions 301A to 301D are connected using both serial connection and parallel connection. Can be configured. In this case, what is necessary is just to switch the connection state of stack part 301A-301D and the circuit 4C according to the voltage which should be applied to the auxiliary machine 5 or PCS70.

  Further, as in the fuel cell system according to the fourth embodiment shown in FIG. 9, the fuel cell unit in which the main stack portion 401M and the first to fourth stack portions 401A to 401D are connected by using both serial connection and parallel connection. The circuit 4D can also be configured using 60D. In this case, the connection state between the main stack unit 401M and the first to fourth stack units 401A to 401D and the circuit 4D may be switched according to the voltage to be applied to the auxiliary machine 5 or the PCS 70.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments. The present invention is modified without departing from the scope described in the claims or applied to others. It may be.

  For example, in the first to third embodiments, the solid oxide fuel cell is used. However, the present invention is not limited to this. For example, the solid oxide fuel cell (SOFC), the phosphoric acid fuel cell (PAFC), and the molten carbonate are used. A fuel cell (MCFC) may be adopted. Further, as the fuel cell unit, the configuration in which a plurality of stack portions are physically in close contact with each other has been described as an example, but a configuration in which the plurality of stack portions are electrically connected by wiring or the like can also be used. .

  Incidentally, in the first to third embodiments, the voltage of the generated power supplied to the auxiliary machine 5 is maintained, but instead of or in addition to this, the generated power supplied to the PCS 70 is configured. You may be comprised so that the voltage of electric power may be maintained.

  Moreover, although the said embodiment is comprised so that the voltage of the generated electric power output may be maintained at 24V, you may be comprised so that 5V, 12V, 48V, or another voltage may be maintained. Moreover, although the voltage of the generated electric power output is maintained at a predetermined voltage, it may be maintained within a predetermined voltage range.

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 3, 3a-f ... Relay part, 4, 4A-4D ... Circuit (circuit part), 5 ... Auxiliary machine, 80 ... Voltage detection part, 100 ... Fuel cell, 101 ... Fuel cell stack Part (stack part), 101A, 201A, 301A, 401A ... first stack part (stack part), 101B, 201B, 301B, 401B ... second stack part (stack part), 101C, 201C, 301C, 401C ... third Stack part (stack part), 301D, 401D... Fourth stack part (stack part), 401M... Main stack part (stack part).

Claims (5)

A plurality of stack parts in which fuel cells are connected in series;
A voltage detection unit for detecting a voltage of each of the plurality of stack units;
A power adjustment unit for adjusting the power generated in the stack unit;
One or more auxiliary machines operated by the generated power output from the stack unit;
A circuit unit electrically connecting the plurality of stack units in parallel to the auxiliary machine and the power adjustment unit ;
A relay unit that is provided in the circuit unit and switches a connection state between the stack unit and the circuit unit in accordance with each voltage of the plurality of stack units detected by the voltage detection unit ;
In the relay unit, when the voltage detection unit detects a voltage drop in at least one of the plurality of stack units, the stack unit in which the voltage detection unit detects a voltage drop among the plurality of stack units. The fuel cell system is characterized in that the connection state between the stack part and the circuit part is switched so that power supply to the auxiliary machine among the auxiliary machine and the power adjustment part is cut off . The relay unit electrically connects all of the plurality of stack units with the auxiliary device and the power adjustment unit when voltage drop of the plurality of stack units is not detected by the voltage detection unit. The fuel cell system according to claim 1. The relay unit is
When the voltage drop of the plurality of stack units is not detected by the voltage detection unit, all of the plurality of stack units and the power adjustment unit are electrically connected, and any stack unit in the plurality of stack units And the auxiliary machine are electrically connected,
When a voltage drop in any one of the stack units is detected by the voltage detection unit, all of the plurality of stack units are electrically connected to the power adjustment unit, and any one of the plurality of stack units is 2. The fuel cell system according to claim 1, wherein the stack unit different from the stack unit is electrically connected to the auxiliary machine. 2. The fuel cell system according to claim 1, wherein the circuit unit further electrically connects the plurality of stack units to the auxiliary machine and the power adjustment unit in series. The relay unit switches the circuit unit so that the voltage of the generated power output from the stack unit is maintained at a predetermined voltage,
The fuel cell system according to any one of claims 1 to 4 , wherein the predetermined voltage is 5V, 12V, 24V, or 48V.

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