JP2011134530A - Control method of fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable superior power generation of power generating cells mutually different in power generating performance, and inhibit degradation of performance and durability of the power generating cells. <P>SOLUTION: A controlling method of a fuel cell system 10 has: a step of setting a load region in which power generating performance of the power generating cells 30a, 30b become equal; a step of supplying electric power to a driving motor 26 only from a battery 22 when demand load of the driving motor 26 is less than the lower limit of the load region; a step of supplying electric power to the driving motor 26 from a fuel cell stack 12 while stopping electric power supply from the battery 22 when the demand load is within the load region; and a step of supplying electric power to the driving motor 26 from the fuel cell stack 12 and of supplying shortage power to the driving motor 26 from the battery 22 when the demand load is over the upper limit of the load region. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention includes a power generation cell in which an electrolyte / electrode structure in which a pair of electrodes are disposed on both surfaces of an electrolyte and a separator are stacked, a fuel cell stack in which a plurality of the power generation cells are stacked, and the fuel cell The present invention relates to a control method for a fuel cell system including a power storage device that supplies power from a stack and supplies power to a load.

  In general, for example, a fuel cell includes an anode side electrode composed of a catalyst layer (electrode catalyst layer) and a gas diffusion layer (porous carbon) on both sides of a solid polymer electrolyte membrane composed of a polymer ion exchange membrane, and An electrolyte membrane / electrode structure (MEA) provided with a cathode-side electrode is sandwiched between separators (bipolar plates). Usually, a fuel cell stack in which a predetermined number of the fuel cells are stacked is used for in-vehicle use, for example.

  By the way, in the fuel cell, when the conditioning of the fuel cell is insufficient or when the performance of the fuel cell is decreasing, the output power of the fuel cell rapidly decreases.

  Thus, for example, a fuel cell system disclosed in Patent Document 1 is known in order to enable appropriate power extraction without causing the fuel cell to be overloaded. This fuel cell system includes a fuel cell that generates power by supplying fuel gas and an oxidant gas, and a fuel cell output limit that limits output from the fuel cell when the operating temperature of the fuel cell is in a predetermined temperature range. Means.

  The fuel cell output limiting means is an output that is the upper limit value of the output that is taken out from the fuel cell based on the operating temperature of the fuel cell and the integrated power that is an integrated value of the amount of power taken out from the fuel cell in the past. The limit value is determined.

  As a result, it is possible to perform optimal output restriction control that also takes into account the condition of fuel cell conditioning and performance degradation, and to take out appropriate power without putting the fuel cell in an overload state. Yes.

JP 2005-209467 A

  By the way, the fuel cell stack may adopt a so-called thinning cooling structure in which a cooling medium flow path is formed between a predetermined number of unit cells. This thinning cooling structure has, for example, two electrolytes / electrode structures in which electrodes are arranged on both sides of each electrolyte, and three separators stacked alternately with the electrolyte / electrode structures, that is, A power generation unit having two power generation cells is provided.

  In the power generation unit, a first oxidant gas flow path and a first fuel gas flow path, and a second oxidant gas flow path and a second fuel gas flow path are formed with each electrolyte / electrode structure interposed therebetween. In addition, a cooling medium flow path through which the cooling medium flows is formed between the power generation units.

  As described above, in the thinning cooling structure, each power generation cell adjacent in the power generation unit has a different fluid flow path structure. For this reason, a difference is likely to occur in the temperature environment, the state of residual water, and the like between adjacent power generation cells. For example, although the first fuel gas flow path provided in one power generation cell is adjacent to the cooling medium flow path, the second fuel gas flow path provided in the other power generation cell is greatly larger than the cooling medium flow path. It is separated.

  Therefore, the first fuel gas flow path is at a lower temperature than the second fuel gas flow path, and condensed water is easily generated. As a result, there is a problem that a difference occurs in the power generation performance between the one power generation cell and the other power generation cell, and a load is applied to the power generation cell having a low performance, which further deteriorates the performance.

  However, in Patent Document 1 described above, only output restriction control is performed in consideration of the conditioning state and the performance degradation state of the entire fuel cell in which a plurality of power generation cells are stacked. For this reason, there exists a problem that it cannot adapt to the fuel cell which has a power generation cell from which power generation performance differs, respectively.

  The present invention solves this type of problem, can generate power generation cells with different power generation performances, and can prevent deterioration of the performance and durability of the power generation cells as much as possible. An object of the present invention is to provide a control method for a fuel cell system.

  The present invention includes a power generation cell in which an electrolyte / electrode structure in which a pair of electrodes are disposed on both surfaces of an electrolyte and a separator are stacked, and the adjacent power generation cell includes a fuel gas, an oxidant gas, or a cooling medium. The fluid flow paths for flowing at least one of the fluids in the separator surface direction are different from each other, a fuel cell stack in which the plurality of power generation cells are stacked, power is supplied from the fuel cell stack, and a load The present invention relates to a control method of a fuel cell system including a power storage device that supplies electric power to the battery.

  The control method includes a step of setting a load region in which the power generation performance of different power generation cells is equivalent, and a step of supplying power to the load only from a power storage device when a required load is less than a lower limit value of the load region; When the required load is within the load region, the power supply from the power storage device is stopped, while the step of supplying power from the fuel cell stack to the load, and when the required load exceeds the upper limit value of the load region Supplying power from the fuel cell stack to the load and supplying insufficient power from the power storage device to the load.

  The fuel cell stack includes first and second electrolyte / electrode structures in which electrodes are disposed on both sides of each electrolyte, and includes a first separator, the first electrolyte / electrode structure, a second separator, The second electrolyte / electrode structure and the third separator are sequentially stacked, and a first fuel gas flow path is formed between the first separator and the first electrolyte / electrode structure, and the first electrolyte / A first oxidant gas flow path is formed between the electrode structure and the second separator; a second fuel gas flow path is formed between the second separator and the second electrolyte / electrode structure; A power generation unit in which a second oxidant gas is formed between the second electrolyte / electrode structure and the third separator, the third separator and the first separator being adjacent to each other between the power generation units. Cooling medium flowing between It is preferable that the cooling medium flow path is formed.

  The fuel cell stack further includes first, second, and third electrolyte / electrode structures in which electrodes are disposed on both sides of each electrolyte, and the first separator, the first electrolyte / electrode structure, and the second A separator, the second electrolyte / electrode structure, a third separator, a third electrolyte / electrode structure, and a fourth separator are sequentially stacked, and between the first separator and the first electrolyte / electrode structure. A first fuel gas flow path is formed, a first oxidant gas flow path is formed between the first electrolyte / electrode structure and the second separator, and the second separator and the second electrolyte / electrode structure are formed. A second fuel gas flow path is formed between the second separator and the third separator, and a second oxidant gas flow path is formed between the third separator and the third separator. 3rd fuel between 3 electrolyte and electrode structure A gas flow path is formed, and includes a power generation unit in which a third oxidant gas flow path is formed between the third electrolyte / electrode structure and the fourth separator, and the power generation units are adjacent to each other between the power generation units. It is preferable that a cooling medium flow path for flowing a cooling medium is formed between the fourth separator and the first separator.

  According to the present invention, in different power generation cells, load regions where the respective power generation performances are equal are set, and the fuel cell stack is operated when the required load is within the load region. When the required load is less than the lower limit value of the load region, the operation of the fuel cell stack is stopped, while power is supplied from only the power storage device to the load. Furthermore, when the required load exceeds the load region, power is supplied from the fuel cell stack to the load, and insufficient power is supplied from the power storage device to the load.

  As a result, the fuel cell stack is not operated in regions where the power generation performances of the different power generation cells are different, so that it is possible to prevent the load from being concentrated on the power generation cells with low performance. Accordingly, it is possible to suppress the deterioration of the performance and durability of the power generation cell, and each power generation cell generates power in the region with the best performance, so that the power generation efficiency can be easily improved.

1 is a schematic explanatory diagram of a fuel cell system to which a control method according to a first embodiment of the present invention is applied. It is a principal part disassembled perspective explanatory drawing of the electric power generation unit which comprises the said fuel cell system. FIG. 3 is a cross-sectional explanatory view of the fuel cell stack. It is explanatory drawing of the said control method. 5 is a flowchart for determining voltage variation in the control method. It is a flowchart explaining the said control method. It is a principal part disassembled perspective explanatory drawing of the electric power generation unit which comprises the fuel cell system with which the control method concerning the 2nd Embodiment of this invention is applied. It is a cross-sectional explanatory drawing of a fuel cell stack. It is explanatory drawing of the said control method.

  As shown in FIG. 1, a fuel cell system 10 to which a control method according to a first embodiment of the present invention is applied includes a fuel cell stack 12 and an oxidant gas that supplies an oxidant gas to the fuel cell stack 12. A supply device 14, a fuel gas supply device 16 for supplying fuel gas to the fuel cell stack 12, a cooling medium supply device 18 for supplying a cooling medium to the fuel cell stack 12, and a voltage control unit for the fuel cell stack 12. 20, a battery 22 and a vehicle driving motor (load) 26 to which a current (electric power) is supplied via the voltage control unit 20 and an inverter 24 are provided.

  The fuel cell stack 12 is configured by laminating a plurality of power generation units 28 along the arrow A direction. As shown in FIGS. 2 and 3, the power generation unit 28 includes two substantially different power generation cells 30 a and 30 b, and includes a first separator 34, a first electrolyte membrane / electrode structure (electrolyte / electrode structure). Body) 36a, second separator 38, second electrolyte membrane / electrode structure 36b, and third separator 40 are sequentially laminated.

  The 1st separator 34, the 2nd separator 38, and the 3rd separator 40 are comprised, for example with the steel plate, the stainless steel plate, the aluminum plate, the plating treatment steel plate, or the metal plate which performed the surface treatment for corrosion prevention on the metal surface. The 1st separator 34, the 2nd separator 38, and the 3rd separator 40 have a cross-sectional uneven | corrugated shape by pressing a metal thin plate in a waveform. In addition, you may comprise the 1st separator 34, the 2nd separator 38, and the 3rd separator 40 with a carbon separator, for example.

  As shown in FIG. 2, the first electrolyte membrane / electrode structure 36a is set to have a smaller surface area than the second electrolyte membrane / electrode structure 36b. The first and second electrolyte membrane / electrode structures 36a and 36b include, for example, a solid polymer electrolyte membrane 42 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode side sandwiching the solid polymer electrolyte membrane 42 The electrode 44 and the cathode side electrode 46 are provided. The anode side electrode 44 constitutes a so-called stepped MEA having a smaller surface area than the cathode side electrode 46.

  The anode side electrode 44 and the cathode side electrode 46 are uniformly coated with a gas diffusion layer (not shown) made of carbon paper or the like and porous carbon particles carrying a platinum alloy on the surface thereof. And an electrode catalyst layer (not shown) formed. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 42.

  An oxidant gas inlet communication hole 50a for supplying an oxidant gas, for example, an oxygen-containing gas, communicates with each other in the arrow A direction at the upper edge of the long side direction (arrow C direction) of the power generation unit 28. And a fuel gas inlet communication hole 52a for supplying a fuel gas, for example, a hydrogen-containing gas.

  The lower end edge of the power generation unit 28 in the long side direction (arrow C direction) communicates with each other in the direction of arrow A to discharge the fuel gas outlet communication hole 52b for discharging the fuel gas, and for discharging the oxidant gas. The oxidant gas outlet communication hole 50b is provided.

  At one edge of the power generation unit 28 in the short side direction (arrow B direction), there is provided a cooling medium inlet communication hole 54a communicating with each other in the arrow A direction for supplying a cooling medium. A cooling medium outlet communication hole 54b for discharging the cooling medium is provided at the other end edge in the short side direction.

  On the surface 34a of the first separator 34 facing the first electrolyte membrane / electrode structure 36a, for example, a first fuel gas channel 56 extending in the direction of arrow C is provided. The first fuel gas flow channel 56 communicates with the fuel gas inlet communication hole 52a through a plurality of inlet through holes 58a, and communicates with the fuel gas outlet communication hole 52b through a plurality of outlet through holes 58b. A part of the cooling medium flow path 60 that connects the cooling medium inlet communication hole 54 a and the cooling medium outlet communication hole 54 b is formed on the surface 34 b of the first separator 34.

  An oxidant gas inlet communication hole 50a and an oxidant gas outlet communication hole 50b communicate with the surface 38a of the second separator 38 facing the first electrolyte membrane / electrode structure 36a, for example, extending in the direction of arrow C. A first oxidant gas flow path 62 is formed.

  A second fuel gas flow path 64 is provided on the surface 38b of the second separator 38 facing the second electrolyte membrane / electrode structure 36b. The second fuel gas channel 64 communicates with the fuel gas inlet communication hole 52a through the plurality of inlet through holes 66a, and communicates with the fuel gas outlet communication hole 52b through the plurality of outlet through holes 66b.

  A second oxidant gas flow path 68 that connects the oxidant gas inlet communication hole 50a and the oxidant gas outlet communication hole 50b is formed on the surface 40a of the third separator 40 toward the second electrolyte membrane / electrode structure 36b. Is done. A part of the coolant flow path 60 is formed on the surface 40 b of the third separator 40.

  A first seal member 70 is integrally formed on the surfaces 34 a and 34 b of the first separator 34 around the outer peripheral edge of the first separator 34. A second seal member 72 is integrally formed around the outer peripheral edge of the second separator 38 on the surfaces 38a and 38b of the second separator 38, and on the surfaces 40a and 40b of the third separator 40, A third seal member 74 is integrally formed around the outer peripheral edge of the third separator 40.

  When the power generation units 28 are stacked with each other, the first power generation unit 28 extends in the direction of arrow B between the first separator 34 constituting the power generation unit 28 and the third separator 40 constituting the other power generation unit 28. A cooling medium flow path 60 is formed.

  The power generation cell 30a includes a first separator 34, a first electrolyte membrane / electrode structure 36a, and a second separator 38, while the power generation cell 30b includes the second separator 38, the second electrolyte membrane / electrode structure 36b. And the third separator 40.

  The operation of the fuel cell system 10 configured as described above will be described below in relation to the control method according to the first embodiment.

  First, a load region in which the power generation performances of the power generation cells 30a and 30b having different configurations are equal is set. As shown in FIG. 4, at a low load (low current), the performance of the power generation cell 30b is better than that of the power generation cell 30a, whereas at high load (high current), the performance of the power generation cell 30a is It is better than the performance of the power generation cell 30b. And between lower limit value A1-upper limit value A2 is a load field where each power generation performance of power generation cells 30a and 30b becomes equivalent.

  As shown in FIG. 3, in the power generation cell 30 a, the first fuel gas channel 56 is cooled adjacent to the cooling medium channel 60. On the other hand, in the power generation cell 30 b, the second fuel gas channel 64 is separated from the cooling medium channel 60 with the first electrolyte membrane / electrode structure 36 a interposed therebetween, and is higher in temperature than the first fuel gas channel 56. It is easy to become.

  Therefore, in the first fuel gas flow channel 56, the generated water is condensed and stagnant water is likely to be generated, and in the low current region (low load region), the fuel gas flows well in the first fuel gas flow channel 56. I can't. Thereby, the stoichiometric shortage occurs, and the performance of the power generation cell 30a is lower than the performance of the power generation cell 30b.

  On the other hand, in the high current region (high load region), the fuel gas flowing through the first fuel gas channel 56 of the power generation cell 30a is considerably heated, but is cooled by the cooling medium flowing through the cooling medium channel 60. The On the other hand, the fuel gas flowing through the second fuel gas flow path 64 of the power generation cell 30b has a low cooling effect by the cooling medium, and moisture is absorbed from the solid polymer electrolyte membrane 42 of the second electrolyte membrane / electrode structure 36b. Take away. For this reason, the solid polymer electrolyte membrane 42 is easily dried, and the power generation performance of the power generation cell 30b is lower than the power generation performance of the power generation cell 30a.

  Therefore, a process for determining variations in the voltages of the power generation cells 30a and 30b constituting each power generation unit 28 is performed, for example, according to the flowchart shown in FIG.

  First, when the first power generation unit 28 is set (step S1), the process proceeds to step S2, the cell voltage Va (1) of the power generation cell 30a constituting the first power generation unit 28, and the power generation cell. It is determined whether or not the difference from the cell voltage Vb (1) of 30b is less than the threshold value Vth. When it is determined that the voltage difference between the power generation cells 30a and 30b is less than the threshold value Vth (YES in step S2), the process proceeds to step S3, and a detection flag indicating that the voltage is good is included.

  Furthermore, it progresses to step S4 and the 2nd electric power generation unit 28 is set. If it is determined that the second power generation unit 28 is less than the number N of layers (for example, 250) (YES in step S5), the process returns to step S2 to configure the second power generation unit 28. A voltage difference between the power generation cells 30a and 30b is detected.

  If it is determined in step S2 that the voltage difference between the power generation cells 30a and 30b is equal to or greater than the threshold value Vth (NO in step S2), the process proceeds to step S6, where a detection flag of NG is given and determination is made. The process ends.

  As described above, whether the current value that satisfies the output of the supply load is between the current values (lower limit value A1 to upper limit value A2) in which the voltage difference between the power generation cells 30a and 30b is within the threshold value Vth. Is determined. Here, the threshold value Vth is a value determined experimentally and empirically, and can be changed depending on the driving state of the vehicle, the number of power generation cells 30a and 30b having different structures, and the like. For example, in the plurality of power generation units 28, cell average value−cell minimum value, maximum value−minimum value, or normal deviation may be set as the threshold value Vth.

  Next, the fuel cell system 10 controls the ON / OFF of the fuel cell stack 12 and the power supply control from the battery 22 based on the load region (region between the lower limit value A1 and the upper limit value A2) shown in FIG. Is done.

  Specifically, as shown in FIG. 6, when the fuel cell system 10 is activated (step S11), the process proceeds to step S12, and the required load of the drive motor 26 (including other electric devices) is changed to the load region. It is determined whether it is less than the lower limit A1. When it is determined that the required load is less than the lower limit value A1 (YES in step S12), the process proceeds to step S13. In step S <b> 13, the fuel cell stack 12 is not operated (OFF), and power is supplied from only the battery 22 to the drive motor 26.

  If it is determined in step S12 that the required load is equal to or greater than the lower limit value A1 (NO in step S12), the process proceeds to step S15 to determine whether the required load is equal to or less than the upper limit value A2 of the load region. Is done. When it is determined that the required load is equal to or less than the upper limit value A2 (YES in step S15), that is, when the required load of the drive motor 26 is within the load region, the process proceeds to step S16.

  Here, while the power supply from the battery 22 is stopped, the operation of the fuel cell stack 12 is started, and power is supplied from the fuel cell stack 12 to the drive motor 26. In the fuel cell stack 12, surplus power can be used for charging the battery 22.

  As shown in FIG. 1, in the fuel cell stack 12, an oxidant gas such as an oxygen-containing gas (for example, air) is supplied from an oxidant gas supply device 14, and a hydrogen-containing gas (for example, from a fuel gas supply device 16). , Hydrogen gas) or the like is supplied. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied from the cooling medium supply device 18.

  As shown in FIG. 2, the oxidant gas is introduced into the first oxidant gas flow path 62 of the second separator 38 and the second oxidant gas flow path 68 of the third separator 40 from the oxidant gas inlet communication hole 50a. The The oxidant gas moves in the direction of arrow C (the direction of gravity) along the first oxidant gas flow path 62 and is supplied to the cathode side electrode 46 of the first electrolyte membrane / electrode structure 36a. It moves in the direction of arrow C along the oxidant gas flow path 68 and is supplied to the cathode side electrode 46 of the second electrolyte membrane / electrode structure 36b.

  On the other hand, the fuel gas moves from the fuel gas inlet communication hole 52 a to the surface 34 a side through the through hole 58 a of the first separator 34. Therefore, the fuel gas moves in the gravity direction (arrow C direction) along the first fuel gas flow path 56 communicating with the through hole 58a, and is supplied to the anode side electrode 44 of the first electrolyte membrane / electrode structure 36a. Is done.

  Further, the fuel gas moves from the fuel gas inlet communication hole 52a to the surface 38b side through the through hole 66a of the second separator 38. Accordingly, the fuel gas moves in the gravity direction (arrow C direction) along the second fuel gas flow path 64 communicating with the through hole 66a, and is supplied to the anode side electrode 44 of the second electrolyte membrane / electrode structure 36b. The

  Thereby, in the first and second electrolyte membrane / electrode structures 36a and 36b, the oxidant gas supplied to the cathode side electrode 46 and the fuel gas supplied to the anode side electrode 44 are within the electrode catalyst layer. It is consumed by electrochemical reaction to generate electricity.

  Next, the oxidant gas consumed by being supplied to the cathode-side electrodes 46 of the first and second electrolyte membrane / electrode structures 36a, 36b is discharged in the direction of arrow A along the oxidant gas outlet communication hole 50b. The

  The fuel gas consumed by being supplied to the anode electrode 44 of the first electrolyte membrane / electrode structure 36a is led out to the surface 34b side of the first separator 34 through the through hole 58b. The fuel gas led out to the surface 34b side is discharged to the fuel gas outlet communication hole 52b.

  Further, the fuel gas supplied to and consumed by the anode electrode 44 of the second electrolyte membrane / electrode structure 36b is led out to the surface 38a side of the second separator 38 through the through hole 66b. The fuel gas led out to the surface 38a side is discharged into the fuel gas outlet communication hole 52b.

  On the other hand, the cooling medium supplied to the cooling medium inlet communication hole 54 a is the cooling formed between the first separator 34 constituting one power generation unit 28 and the third separator 40 constituting the other power generation unit 28. After being introduced into the medium flow path 60, it flows in the direction of arrow B. The cooling medium cools the first and second electrolyte membrane / electrode structures 36a and 36b, and then is discharged into the cooling medium outlet communication hole 54b.

  Next, as shown in FIG. 6, when it is determined in step S15 that the required load exceeds the upper limit value A2, that is, it exceeds the load region (NO in step S15), the process proceeds to step S17. . Here, the fuel cell stack 12 generates power at the output of the upper limit value A2, and the insufficient power is supplied from the battery 22 to the drive motor 26. That is, in the fuel cell stack 12, a current is drawn between the lower limit value A <b> 1 and the upper limit value A <b> 2 that are load regions, while a necessary current value (insufficient current) is supplemented by the battery 22.

  In this case, in the first embodiment, in the power generation cells 30a and 30b having different configurations, a load region in which each power generation performance is equivalent is set, and the fuel cell stack 12 has a required load by the drive motor 26 within the load region. Is driving.

  When the required load of the drive motor 26 is less than the lower limit value A1 of the load region, the operation of the fuel cell stack 12 is stopped, while power is supplied only from the battery 22 to the drive motor 26. . Further, when the required load of the drive motor 26 exceeds the load region (upper limit value A2), power is supplied from the fuel cell stack 12 to the drive motor 26, and insufficient power is supplied from the battery 22 to the drive motor 26. Has been supplied to.

  Accordingly, the fuel cell stack 12 does not operate in regions where the power generation performances of the power generation cells 30a and 30b having different configurations are different. For example, when the load is low, the load is concentrated on the power generation cell 30a with low performance. On the other hand, when the load is high, it is possible to prevent the load from being concentrated on the power generation cell 30b having low performance.

  Accordingly, it is possible to reliably suppress deterioration in performance and durability of the power generation cells 30a and 30b, and each power generation cell 30a and 30b is generated in the region with the best performance. For this reason, it is possible to easily improve the power generation efficiency of the fuel cell stack 12 as a whole.

  In addition, since the power generation of the fuel cell stack 12 is not performed at the time of low load, if the off state is maintained for a long time, gas replacement, water condensation, and the like may occur, and power generation may not proceed rapidly. Therefore, it is preferable to perform a scavenging process or a gas circulation process as necessary so that the required current value can always be drawn from the fuel cell stack 12.

  FIG. 7 is an exploded perspective view of a main part of the power generation unit 80 constituting the fuel cell system according to the second embodiment of the present invention. Note that the same components as those of the power generation unit 28 constituting the fuel cell system 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The power generation unit 80 includes power generation cells 30a, 30b, and 30c. 7 and 8, the power generation unit 80 includes a first separator 34, a first electrolyte membrane / electrode structure 36a, a second separator 38, a second electrolyte membrane / electrode structure 36b, a third separator 82, A third electrolyte membrane / electrode structure 36c and a fourth separator 84 are provided.

  A second oxidant gas flow path 68 is formed on a surface 82a of the third separator 82 facing the second electrolyte membrane / electrode structure 36b, and a third fuel gas is formed on the surface 82b of the third separator 82. A flow path 86 is provided extending in the direction of arrow C. The third fuel gas channel 86 communicates with the fuel gas inlet communication hole 52a through the plurality of inlet through holes 88a, and communicates with the fuel gas outlet communication hole 52b through the plurality of outlet through holes 88b.

  A third oxidant gas flow path 90 extending in the direction of arrow C is provided on a surface 84a of the fourth separator 84 facing the third electrolyte membrane / electrode structure 36c. A part of the cooling medium flow path 60 is formed on the surface 84 b of the fourth separator 84.

  The power generation cell 30a includes a first separator 34, a first electrolyte membrane / electrode structure 36a, and a second separator 38. The power generation cell 30b includes the second separator 38, the second electrolyte membrane / electrode structure 36b, and the second separator 38. The power generation cell 30c includes the third separator 82, the third electrolyte membrane / electrode structure 36c, and the fourth separator 84.

  The power generation cells 30a, 30b, and 30c have different performance with respect to the load current as shown in FIG. The relationship between the power generation cells 30a and 30c is the same as the relationship between the power generation cells 30a and 30b of the first embodiment.

  The power generation cell 30b is disposed between the power generation cells 30a and 30c and is most distant from the cooling medium flow path 60. For this reason, on the low load side, the power generation cell 30b is kept warmer than the other power generation cells 30a and 30c, and the retained water is less likely to be present in the second fuel gas channel 64. Therefore, the power generation cell 30b has the highest performance on the low load side.

  On the other hand, generated water is generated by the reaction on the high load side, but the power generation cell 30b is less likely to be cooled than the other power generation cells 30b and 30c, and the solid polymer electrolyte membrane 42 is easily dried by high-temperature gas. Thereby, on the high temperature load side, the performance of the power generation cell 30b is lower than that of the other power generation cells 30a and 30c.

  In the second embodiment, in the power generation cells 30a to 30c, a load region in which each power generation performance is equivalent is set, and the power generation unit 80 is operated when the required load is within the load region. When the required load is less than the lower limit value A1 of the load region, the operation of the power generation unit 80 is stopped, while power is supplied to the load only from the battery 22 (see FIG. 1). Furthermore, when the required load exceeds the upper limit A2 of the load region, power is supplied from the power generation unit 80 and insufficient power is supplied from the battery 22. Thereby, in 2nd Embodiment, the effect similar to said 1st Embodiment is acquired.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell system 12 ... Fuel cell stack 14 ... Oxidant gas supply device 16 ... Fuel gas supply device 18 ... Cooling medium supply device 22 ... Battery 26 ... Drive motor 28, 80 ... Power generation unit 30a, 30b, 30c ... Power generation cell 34, 38, 40, 82, 84 ... separators 36a, 36b, 36c ... electrolyte membrane / electrode structure 42 ... solid polymer electrolyte membrane 44 ... anode side electrode 46 ... cathode side electrode 56, 64, 86 ... fuel gas flow path 60 ... Cooling medium flow path 62, 68, 90 ... Oxidant gas flow path

Claims (3)

A power generation cell in which an electrolyte / electrode structure in which a pair of electrodes are disposed on both surfaces of the electrolyte and a separator are stacked is provided, and the adjacent power generation cell is at least one of fuel gas, oxidant gas, and cooling medium A fuel flow path in which a plurality of the power generation cells are stacked, and the fluid flow paths for flowing the fluid in the separator surface direction are different from each other;
A power storage device for supplying power from the fuel cell stack and supplying power to a load;
A control method for a fuel cell system comprising:
Setting a load region in which the power generation performance of the different power generation cells is equivalent; and
When the required load is less than the lower limit value of the load region, supplying power to the load only from the power storage device;
Supplying power from the fuel cell stack to the load while stopping power supply from the power storage device when the required load is within the load region;
When the required load exceeds the upper limit value of the load region, supplying power from the fuel cell stack to the load and supplying insufficient power from the power storage device to the load;
A control method for a fuel cell system, comprising:   2. The control method according to claim 1, wherein the fuel cell stack includes first and second electrolyte / electrode structures in which electrodes are disposed on both sides of each electrolyte, and includes a first separator and the first electrolyte / electrode. A structure, a second separator, the second electrolyte / electrode structure, and a third separator are sequentially stacked, and a first fuel gas flow path is provided between the first separator and the first electrolyte / electrode structure. Formed, a first oxidant gas flow path is formed between the first electrolyte / electrode structure and the second separator, and a second is formed between the second separator and the second electrolyte / electrode structure. A fuel gas flow path is formed, and includes a power generation unit in which a second oxidant gas is formed between the second electrolyte / electrode structure and the third separator, and the power generation units are adjacent to each other. A third separator and said Control method for a fuel cell system, characterized in that the cooling medium flow passage for flowing the cooling medium between first separator is formed.   2. The control method according to claim 1, wherein the fuel cell stack includes first, second, and third electrolyte / electrode structures in which electrodes are disposed on both sides of each electrolyte, the first separator, and the first separator. An electrolyte / electrode structure, a second separator, the second electrolyte / electrode structure, a third separator, a third electrolyte / electrode structure, and a fourth separator are sequentially stacked, and the first separator and the first electrolyte A first fuel gas flow path is formed between the electrode structure and a first oxidant gas flow path is formed between the first electrolyte electrode structure and the second separator; A second fuel gas flow path is formed between the second electrolyte / electrode structure and the second separator / electrode structure, and a second oxidant gas flow path is formed between the second electrolyte / electrode structure and the third separator. The third separator and the third electrolysis A power generation unit in which a third fuel gas flow path is formed between the electrode structure and a third oxidant gas flow path is formed between the third electrolyte electrode structure and the fourth separator; A control method for a fuel cell system, wherein a cooling medium flow path for flowing a cooling medium between the fourth separator and the first separator adjacent to each other is formed between the power generation units.

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