JP5910127B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system, and more particularly to a technique for starting a stack (fuel cell) immediately to reach a target output required for the system.

  In a fuel cell system such as a solid oxide fuel cell system, when starting a fuel cell stack (hereinafter simply referred to as “stack”), it is necessary to raise the temperature of the stack to a power generation start temperature. Thus, a combustion burner is installed on the upstream side of the cathode of the stack, the combustion burner is combusted when the stack is activated, and the generated combustion gas is supplied to the cathode to raise the temperature of the stack. Then, after the stack reaches the power generation possible temperature, power generation by the stack is started, and when the stack temperature reaches a predetermined value and the generated current or generated power reaches the predetermined value, the combustion burner is stopped and rated operation is performed. State (see, for example, Patent Document 1).

JP 2009-146647 A

  However, the conventional example disclosed in Patent Document 1 described above is intended to control the timing at which the combustion burner is stopped, and before the stack reaches the rated operation state (a state where a constant output can be obtained). Since the heating by the combustion burner is stopped and then gradually shifted to the rated operation, stopping the combustion burner may delay the rate of temperature rise of the stack, so that the target output can be reached quickly. There was a problem that it was difficult to apply to the required on-vehicle fuel cell.

  The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a fuel cell system that can immediately reach a target output when the fuel cell is started. There is.

To achieve the above object, the present invention is provided with a fuel cell, an oxidant supply means for supplying an oxidant to the cathode of the fuel cell, and an oxidant supply means and a cathode. And an oxidant heating means for heating the outputted oxidant. Further, when the fuel cell is started, the temperature of the fuel cell is controlled by supplying the oxidant heated by the oxidant heating means to the cathode, and after the fuel cell reaches the power generation possible temperature, the target of the fuel cell is controlled. When the output is less than or equal to a preset predetermined value X1, both of the following (a) and (b) are performed until the fuel cell reaches a predetermined target output or target temperature, and the target output is a predetermined value. When exceeding X1, the following (b) and at least one of (a) and (c) are performed until the fuel cell reaches a predetermined target output or target temperature .
(A) Control for setting the oxygen excess rate of the oxidant output from the oxidant heating means to be lower than the oxygen excess rate at the target output of the fuel cell (b) The output per unit area of the fuel cell peak (C) Heating control by oxidant heating means is set so that the cell voltage is set near the cell voltage.

In the fuel cell system according to the present invention, after the temperature of the fuel cell reaches the power generation possible temperature, the temperature rise control is performed until the target output during normal operation or the target temperature is reached . At this time, when the target output of the fuel cell is equal to or less than a predetermined value X1, the oxygen excess rate of the oxidant output from the oxidant heating means is set to the oxygen excess rate at the target output of the fuel cell. And (b) control for setting the cell voltage when the output per unit area of the fuel cell reaches a peak and setting the cell voltage to be close to the cell voltage. To implement. When the target output exceeds the predetermined value X1, (b) the cell voltage when the output per unit area of the fuel cell reaches a peak is set, and the cell voltage is set to be close to this cell voltage. Control, (a) control for setting the oxygen excess rate of the oxidant output from the oxidant heating means to be lower than the oxygen excess rate at the target output of the fuel cell, and (c) heating control by the oxidant heating means. Since at least one of the controls is performed, the output of the fuel cell can quickly reach the target output.

1 is a block diagram showing a configuration of a fuel cell system according to a first embodiment of the present invention. It is a flowchart which shows the process sequence at the time of stack | startup of the fuel cell system which concerns on 1st Embodiment of this invention. It is a flowchart which shows the process sequence of stack heating control of the fuel cell system which concerns on 1st Embodiment of this invention. It is a flowchart which shows the process sequence of stack temperature rising control of the fuel cell system which concerns on 1st Embodiment of this invention. It is a flowchart which shows the process sequence of a burner and oxygen excess rate control [1] of the fuel cell system which concerns on 1st Embodiment of this invention. It is a flowchart which shows the process sequence of a burner and oxygen excess rate control [2] of the fuel cell system which concerns on 1st Embodiment of this invention. It is a flowchart which shows the process sequence of oxygen excess rate control [1] of the fuel cell system which concerns on 1st Embodiment of this invention. It is a flowchart which shows the process sequence of oxygen excess rate control [2] of the fuel cell system which concerns on 1st Embodiment of this invention. It is a block diagram which shows the structure of the fuel cell system which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the process sequence at the time of stack | stuck starting of the fuel cell system which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the process sequence of 2nd stack | stuck temperature rising control [1] of the fuel cell system which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the process sequence of a burner and oxygen excess rate control [3] of the fuel cell system concerning 2nd Embodiment of this invention. It is a flowchart which shows the process sequence of 2nd stack | stuck temperature rising control [2] of the fuel cell system which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the process sequence of oxygen excess rate control [3] of the fuel cell system which concerns on 2nd Embodiment of this invention. It is a characteristic view which shows the relationship between the target output of the fuel cell system which concerns on embodiment of this invention, and the energy input at the time of starting. It is a characteristic view which shows the relationship between the current density, cell voltage, and output density of the fuel cell system which concerns on embodiment of this invention. It is a characteristic view which shows the relationship between the difference of the target output and the present output, and the output temperature of a combustion burner of the fuel cell system which concerns on embodiment of this invention. It is a block diagram which shows the structure which connected the fuel cell system which concerns on 3rd Embodiment of this invention to the external load. It is a flowchart which shows the processing operation of the fuel cell system which concerns on 3rd Embodiment of this invention. It is a block diagram which shows the structure which connected the fuel cell system which concerns on 4th Embodiment of this invention to the external load. It is a flowchart which shows the processing operation of the fuel cell system which concerns on 4th Embodiment of this invention. It is a map which shows the relationship between SOC used by the fuel cell system which concerns on 4th Embodiment of this invention, and the request | requirement output of an external load. It is a block diagram which shows the structure which connected the fuel cell system which concerns on 5th Embodiment of this invention to the external load. It is a flowchart which shows the processing operation of the fuel cell system which concerns on 5th Embodiment of this invention. It is a characteristic view which shows the time series data of the target temperature and target output which are used with the fuel cell system which concerns on 5th Embodiment of this invention. It is a map which shows the relationship between SOC used by the fuel cell system which concerns on 5th Embodiment of this invention, and an output.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Description of First Embodiment]
FIG. 1 is a block diagram showing the configuration of the fuel cell system according to the first embodiment of the present invention. As shown in FIG. 1, the fuel cell system 100 supplies a fuel cell stack 11 (hereinafter abbreviated as “stack 11”) having a cathode 11a and an anode 11b, and supplies air (oxidant) to the cathode 11a. An air blower (oxidant supply means) 12, a heat exchanger 13 for heating air sent from the air blower 12, and a first fuel pump 14 for supplying fuel such as hydrocarbon fuel to the anode 11 b of the stack 11; An evaporator 25 that vaporizes the fuel delivered from the first fuel pump 14, and a heat exchange type pre-reformer 15 that reforms the fuel vaporized by the evaporator 25 and supplies the reformed fuel to the anode 11b. ing.

  The heat exchange type pre-reformer 15 includes a pre-reformer 16 and a combustor 17 that heats the pre-reformer 16, and the combustor 17 includes one of the air sent from the air blower 12. And the anode off-gas (gas discharged from the anode 11b) is supplied and combusted to heat the pre-reformer 16. The output side of the combustor 17 is connected to the high temperature side of the heat exchanger 13, and the exhaust gas output from the combustor 17 is used as a heating gas for the heat exchanger 13.

  The pre-reformer 16 is supplied with a part of the air sent from the air blower 12, the fuel sent from the first fuel pump 14 and vaporized by the evaporator 25, and a part of the anode off-gas. The fuel is reformed by the heat generated in the combustor 17, and the reformed fuel is supplied to the anode 11 b of the stack 11.

  The output side of the air blower 12 is connected to the low temperature side of the heat exchanger 13, and the outlet thereof is connected to a combustion burner (oxidant heating means) 21 for heating the cathode 11a when the stack 11 is started. Yes. The combustion burner 21 is connected to the second fuel pump 22, and fuel is supplied from the second fuel pump 22. Therefore, the combustion burner 21 is supplied with the air heated by the heat exchanger 13 and the fuel delivered from the second fuel pump 22 and burns. Then, this combustion gas is supplied to the cathode 11 a of the stack 11.

  An anode off-gas circulator 23 is provided on the output side of the anode 11b. The anode off-gas output from the anode 11b is branched into two systems, and the anode off-gas branched into one is supplied to the pre-reformer 16, The anode off gas branched to the other side is supplied to the combustor 17.

  Between the air blower 12 and the heat exchange type pre-reformer 15, flow control devices 19 and 20 are provided. The air flow rate supplied to the pre-reformer 16 and the air flow rate supplied to the combustor 17 are provided. Can be adjusted to a desired flow rate.

  The stack 11 is provided with an inlet temperature sensor 41a that measures the temperature near the inlet, an outlet temperature sensor 41b that measures the temperature near the outlet, and a current / voltage sensor 42 that detects the output current and voltage of the stack 11. Yes.

  In addition, the fuel cell system 100 according to the present embodiment includes a control unit (control unit) 31 that comprehensively controls the entire system. In particular, the control unit 31 measures the stack temperature (for example, the average value of the inlet temperature and the outlet temperature) measured by the inlet temperature sensor 41a and the outlet temperature sensor 41b provided in the stack 11, and the current / voltage sensor 42. Based on the calculated power generation output, the fuel supply amount by the second fuel pump 22 and the air amount by the air blower 12 are controlled. In addition, the control part 31 can be comprised as an integrated computer which consists of memory | storage means, such as central processing unit (CPU), RAM, ROM, a hard disk, for example.

[Description of Operation of First Embodiment]
Next, the processing operation at the start-up of the fuel cell system 100 according to the first embodiment will be described with reference to the flowcharts shown in FIGS. FIG. 2 is a flowchart showing the entire processing procedure of the stack temperature raising operation when the fuel cell system 100 according to the first embodiment of the present invention is started.

  First, in step S11, the control unit 31 determines whether or not to activate the stack 11, and if so (YES in step S11), in step S12, the control unit 31 performs stacking by the combustion burner 21. It is determined whether or not the heating of No. 11 has been completed. If heating has not been completed (NO in step S12), in step S13, the control unit 31 continuously controls the heating of the stack 11 by the combustion burner 21. The details of the stack heating control will be described later with reference to the flowchart shown in FIG. Thereafter, the process proceeds to step S14.

  In step S14, the control unit 31 determines whether or not the stack temperature increase control is finished. If the temperature increase control has not ended (NO in step S14), in step S15, the control unit 31 performs stack temperature increase control. Details of the stack temperature increase control will be described later with reference to the flowchart shown in FIG. Thereafter, this process is terminated. The “stack heating control” is control for raising the temperature of the stack 11 to a power generation possible temperature, and the “stack temperature rise control” is for further power generation by further raising the temperature of the stack 11 heated to the power generation possible temperature. This is a control to raise the target temperature.

  Next, the processing procedure of the heating control of the stack 11 by the combustion burner 21 shown in step S13 of FIG. 2 will be described with reference to the flowchart shown in FIG.

  First, in step S <b> 21, the control unit 31 activates the air blower 12 and supplies air to the combustion burner 21.

  In step S <b> 22, the control unit 31 starts the combustion burner 21 and burns the combustion burner 21 with the fuel supplied from the second fuel pump 22 and the air supplied from the air blower 12. And the combustion gas produced | generated in the combustion burner 21 is supplied in the cathode 11a of the stack 11, and the cathode 11a is heated up.

  In step S23, the control unit 31 controls the amount of air supplied from the air blower 12 into the cathode 11a, and further controls the amount of fuel supplied to the combustion burner 21 in step S24. Thus, the amount of combustion gas supplied from the combustion burner 21 to the cathode 11a and the outlet temperature of the combustion burner 21 are controlled to be in a predetermined state.

  In step S25, the control unit 31 detects the temperature of the stack 11 (for example, an average value of the inlet temperature and the outlet temperature) by the inlet temperature sensor 41a and the outlet temperature sensor 41b. In step S26, the temperature of the stack 11 is a predetermined value. It is determined whether or not the temperature (the temperature at which the stack 11 can generate power) has been reached. If the predetermined temperature has not been reached (NO in step S26), the process returns to step S23, and if the predetermined temperature has been reached (YES in step S26), in step S27, the control unit 31 performs heating by the combustion burner 21. finish. Then, the heating end determination flag is turned on. In this way, the stack 11 can be heated up to a power generation possible temperature.

  Next, detailed processing of the stack temperature raising control shown in step S15 of FIG. 2 will be described with reference to the flowchart shown in FIG. In step S31 shown in FIG. 4, the control unit 31 detects the temperature of the stack 11 and the output (calculated from the power and current). In step S32, the control unit 31 determines whether or not the output of the stack 11 has reached the target output.

  If the target output has been reached (YES in step S32), in step S35, the current value is controlled so that the power generation output of the stack 11 becomes the target output. In step S36, a flag indicating that the target output has been reached is turned on. Thereafter, the process proceeds to step S37.

  On the other hand, if the target output has not been reached (NO in step S32), in step S33, the control unit 31 reads a cell voltage target value stored in a memory (not shown) or the like, and further in step S34. Then, the cell voltage is controlled to be the cell voltage target value. Specifically, by controlling the cell voltage to be a predetermined value, the output of the stack 11 is controlled to become the target output as the temperature of the stack 11 rises. The stack 11 is a structure in which a plurality of cells are stacked, and the cell voltage is the output voltage of each cell. At this time, the cell voltage is desirably controlled to about 0.5V. The control of the cell voltage will be described later with reference to FIG. Thereafter, the process proceeds to step S37.

  In step S37, the control unit 31 determines whether or not the target output of the stack 11 is larger than a predetermined output set in advance. That is, as shown in the characteristic curve shown in FIG. 15, it is determined whether or not the target output is larger than a predetermined value X1 set in advance. Here, as shown in FIG. 15, the relationship between the target output of the stack 11 and the energy input to the stack 11 is different between when the combustion burner 21 is on and when it is off.

  15 shows the characteristics when the combustion burner 21 is turned on, and the curve Q2 shows the characteristics when the combustion burner 21 is turned off. When the target output exceeds X1, the curve Q1 is turned on. However, it turns out that input energy can be reduced. Therefore, in the fuel cell system according to this embodiment, when the target output exceeds X1, the stack 11 is heated to the target temperature by operating the combustion burner 21, and when the target output is below X1, The stack 11 is heated without operating the combustion burner 21. Here, the “target temperature” is a temperature when the stack 11 is in steady operation, and is a temperature higher than the power generation possible temperature.

  When the target output is larger than the predetermined value X1 (YES in step S37), in step S38, the control unit 31 determines whether or not the temperature of the stack 11 has reached the target temperature. If the target temperature has not been reached (NO in step S38), in step S39, the control unit 31 performs burner and oxygen excess rate control [1]. Details of this control will be described later with reference to the flowchart shown in FIG. On the other hand, when the target temperature has been reached (YES in step S38), in step S40, the control unit 31 executes burner and oxygen excess rate control [2]. Details of this control will be described later with reference to the flowchart shown in FIG.

  If it is determined in step S37 that the target output is less than or equal to the predetermined value X1 (NO in step S37), in step S41, the control unit 31 has reached the target temperature of the stack 11. Determine whether or not. If the target temperature has not been reached (NO in step S41), in step S42, the control unit 31 performs oxygen excess rate control [1]. Details of this control will be described later with reference to the flowchart shown in FIG. On the other hand, when the target temperature has been reached (YES in step S41), in step S43, the control unit 31 performs oxygen excess rate control [2]. Details of this control will be described later with reference to the flowchart shown in FIG.

  When any one of the burner and oxygen excess rate control [1], [2] and the oxygen excess rate control [1], [2] is executed, in step S44, the control unit 31 stacks. It is determined whether the temperature of 11 has reached the target temperature. If the target temperature has been reached (YES in step S44), in step S45, the control unit 31 determines that the target temperature has been reached, and turns on the target temperature arrival determination flag.

  In step S46, the control unit 31 determines whether the temperature of the stack 11 and the output have reached the target temperature and the target output. If the target temperature and the target output have not been reached, the process ends. On the other hand, if the target temperature and the target output have been reached, in step S47, the control unit 31 ends the stack temperature increase control and turns on the stack temperature increase control end determination flag. When the target temperature arrival flag is turned on in the process of step S45 and the stack temperature increase control end flag is turned on in the process of step S47, the stack temperature increase control shown in step S15 of FIG. finish.

  Next, the control of the cell voltage to about 0.5 V in the process of step S34 will be described with reference to the characteristic diagram shown in FIG. FIG. 16 shows the relationship between the current density (A / cm 2), the cell voltage (V), and the output density (W / cm 2). The reference symbol V1 indicates the output voltage at the temperature T1, and the reference symbol V2 indicates The output voltage at the temperature T2 (> T1) is shown, and the symbol V3 shows the output voltage at the temperature T3 (> T2). Reference sign W1 indicates the output density (W / cm 2) at the temperature T1, reference sign W2 indicates the output density at the temperature T2, and reference sign W3 indicates the output density at the temperature T3.

  As can be understood from the characteristic diagram of FIG. 16, at each temperature T1, T2, T3, when the cell voltage is around 0.5 (V), the output power per unit area, that is, the output density is a peak value. It has become. Therefore, in the process shown in step S34 of FIG. 4, by controlling the cell voltage to about 0.5 (V), the output power can be increased and thus a large amount of heat can be obtained. That is, the temperature rise effect of the stack 11 can be improved by controlling the cell voltage to about 0.5 (V).

  Next, the detailed processing procedure of the burner and oxygen excess rate control [1] shown in step S39 of FIG. 4 will be described with reference to the flowchart shown in FIG. First, in step S51, the control unit 31 reads the target oxygen excess rate. In this process, the target oxygen excess rate (for example, 1.3) stored in advance in a memory (not shown) or the like is read and acquired. Here, the target oxygen excess rate stored in the memory or the like is set to a numerical value lower than the target oxygen excess rate during normal operation. Therefore, if the amount of oxygen supplied to the cathode 11a is controlled using this target oxygen excess rate, less oxygen (air) is supplied than during normal operation, so the temperature of the stack 11 rises. .

  In step S52, the control unit 31 reads the target outlet temperature of the combustion burner 21. In this process, the target outlet temperature of the combustion burner 21 stored in advance in a memory (not shown) or the like is read and acquired.

  In step S <b> 53, the control unit 31 detects the output current of the stack 11 by the current / voltage sensor 42 provided in the stack 11.

  In step S54, the control unit 31 calculates the minimum required oxygen amount according to the output current detected in the process of step S53. Specifically, a numerical value obtained by multiplying the minimum value of the oxygen amount necessary for obtaining the output current by the oxygen excess obtained in the process of step S51 is obtained as the required oxygen amount.

  In step S55, the control unit 31 calculates the required fuel amount of the combustion burner 21 necessary to obtain this temperature based on the target outlet temperature of the combustion burner 21 acquired in the process of step S52. That is, if the required oxygen amount of the stack 11 and the target outlet temperature of the combustion burner 21 are determined, the required fuel amount can be obtained.

  In step S56, the control unit 31 calculates the amount of air sent from the air blower 12 based on the required oxygen amount obtained in the process of step S54 and the required fuel amount obtained in the process of step S55 (in this case, In consideration of the amount of oxygen consumed by combustion in the combustion burner 21, the amount of air is calculated so that the oxygen excess rate at the outlet of the combustion burner 21 becomes the required oxygen amount set in the process of step S54). In other words, the air sent from the air blower 12 is supplied to the combustion burner 21, and the amount of oxygen in the gas discharged after combustion by the combustion burner 21 becomes the required amount of oxygen obtained in the process of step S54. Next, the required cathode air amount is calculated.

  In step S57, the control unit 31 sets the amount of air obtained in the process of step S56 as the amount of air supplied to the cathode 11a, and further sets the amount of fuel supplied to the combustion burner 21 in step S58. The air blower 12 and the second fuel pump 22 are controlled so that the air amount and the fuel amount become the same.

  Thus, the stack 11 can be heated by controlling the amount of air supplied to the cathode 11a and the amount of fuel supplied to the combustion burner 21 based on the oxygen excess rate. That is, the temperature of the stack 11 can be rapidly raised by supplying the combustion gas of the combustion burner 21 and setting the oxygen excess rate lower than that during normal operation.

  Next, the detailed procedure of the burner and oxygen excess rate control [2] shown in step S40 of FIG. 4 will be described with reference to the flowchart shown in FIG. In this process, unlike the burner and oxygen excess rate control [1] described above, the stack 11 has reached the target temperature, so the temperature difference ΔT (outlet temperature-inlet temperature) between the outlet and the inlet of the stack 11 or the stack. The combustion burner 21 and the oxygen excess rate are controlled based on the outlet temperature of 11 so that the temperature of the stack 11 maintains the target temperature.

  First, in step S61, the control unit 31 detects a temperature difference ΔT between the outlet temperature of the stack 11 and the inlet temperature. Alternatively, the outlet temperature of the cathode 11a is detected.

  In step S <b> 62, the control unit 31 reads the target outlet temperature of the combustion burner 21. In this process, the target outlet temperature stored in the memory or the like is read and acquired as in the process of step S52 of FIG.

  In step S63, the control unit 31 calculates the amount of excess oxygen combustion gas supplied to the cathode 11a, that is, the flow rate of excess oxygen gas discharged after combustion in the combustion burner 21 (hereinafter referred to as “supply gas amount”). . And it controls so that it may become this supply gas amount.

  Specifically, when the temperature difference ΔT is detected in the process of step S61, the supply gas amount is increased by a predetermined amount when ΔT> 0, and the supply gas amount is increased by a predetermined amount when ΔT <0. By decreasing, the temperature difference ΔT is controlled to approach zero. If the outlet temperature is detected in step S61, the supply gas amount is increased by a predetermined amount when (exit temperature)> (target temperature), and the supply gas when (exit temperature) <(target temperature). By reducing the amount by a predetermined amount, control is performed so that the temperature of the stack 11 becomes the target temperature.

  In step S64, the control unit 31 calculates the required cathode air amount sent from the air blower 12 based on the supply gas amount obtained in the process of step S63. That is, the air sent from the air blower 12 is supplied to the combustion burner 21, and the amount of gas discharged after combustion by the combustion burner 21 becomes the supply gas amount obtained in the process of step S63. The amount of air sent out by the blower 12 is calculated.

  In step S65, based on the target outlet temperature of the combustion burner 21 acquired in the process of step S62, the control unit 31 calculates the required fuel amount of the combustion burner 21 required to reach this temperature.

  In step S66, the control unit 31 sets the amount of air obtained in the process of step S64 as the amount of air supplied to the cathode 11a, and further sets the amount of fuel supplied to the combustion burner 21 in step S67. The air blower 12 and the second fuel pump 22 are controlled so that the air amount and the fuel amount become the same.

  Thus, by controlling the amount of air supplied to the cathode 11a and the amount of fuel supplied to the combustion burner 21 based on the oxygen excess rate, the temperature of the stack 11 can be maintained at the target temperature.

  Next, the detailed processing procedure of oxygen excess rate control [1] shown in step S42 of FIG. 4 will be described with reference to the flowchart shown in FIG. First, in step S71, the control unit 31 reads the target oxygen excess rate. In this process, the target oxygen excess rate stored in advance in a memory (not shown) or the like is read and acquired. This oxygen excess rate is set to a value lower than the oxygen excess rate during normal operation of the stack 11.

  In step S <b> 72, the control unit 31 detects the output current of the stack 11 by the current / voltage sensor 42 provided in the stack 11.

  In step S73, the control unit 31 calculates the minimum required oxygen amount corresponding to the output current detected in the process of step S72. Specifically, a numerical value obtained by multiplying the minimum value of the oxygen amount necessary for obtaining the output current by the oxygen excess rate obtained in the process of step S71 is obtained as the required oxygen amount.

  In step S74, the control unit 31 calculates the amount of air sent from the air blower 12 based on the required oxygen amount obtained in the process of step S73. That is, the amount of air necessary to supply the required oxygen amount to the cathode 11a is calculated.

  In step S75, the control unit 31 sets the amount of air obtained in the process of step S74 as the amount of air supplied to the cathode 11a, and controls the air blower 12 so as to be this air.

  Thus, the stack 11 can be heated by controlling the amount of air supplied to the cathode 11a based on the oxygen excess rate. That is, as described above, since the target oxygen excess rate is set lower than the oxygen excess rate during normal operation, the amount of oxygen (air amount) supplied to the cathode 11a is smaller than during normal operation, and cooling is performed. The effect is reduced, and as a result, the temperature of the stack 11 can be raised.

  Next, the detailed processing procedure of oxygen excess rate control [2] shown in step S43 of FIG. 4 will be described with reference to the flowchart shown in FIG. In this process, unlike the oxygen excess rate control [1] described above, since the stack 11 has reached the target temperature, the temperature difference ΔT (outlet temperature−inlet temperature) between the outlet and the inlet of the stack 11 or the stack 11 Based on the outlet temperature, the oxygen excess rate is controlled so that the temperature of the stack 11 maintains the target temperature.

  First, in step S81, the control unit 31 detects a temperature difference ΔT between the outlet temperature of the stack 11 and the inlet temperature. Alternatively, the outlet temperature of the cathode 11a is detected.

  In step S <b> 82, the control unit 31 calculates the required cathode air amount sent from the air blower 12. And it controls so that it may become this air quantity. Specifically, when the temperature difference ΔT is detected in the process of step S81, the supply air amount is increased by a predetermined amount when ΔT> 0, and the supply air amount is increased by a predetermined amount when ΔT <0. By decreasing, the temperature difference ΔT is controlled to approach zero. When the outlet temperature is detected in step S81, the supply air amount is increased by a predetermined amount when (exit temperature)> (target temperature), and the supply air when (exit temperature) <(target temperature). By reducing the amount by a predetermined amount, the temperature of the stack 11 is controlled so as to approach the target temperature.

  In step S83, the control unit 31 sets the amount of air obtained in the process of step S82 as the amount of air supplied to the cathode 11a, and controls the air blower 12 so as to be this air.

  Thus, the stack 11 can be maintained at the target temperature by controlling the amount of air supplied to the cathode 11a based on the oxygen excess rate.

  Thus, in the fuel cell system according to the first embodiment of the present invention, the cell voltage of the stack 11, the oxygen excess ratio of the gas supplied to the cathode 11a, and the combustion gas output from the combustion burner 21 By controlling at least one, the temperature of the stack 11 that has been raised to the power generation possible temperature is raised to the target temperature required for operation at the target output, so that the temperature rise of the stack 11 is promoted and the target temperature or The target output can be reached. Therefore, it is extremely useful in the case of a stack that requires quick response, for example, when mounted on a vehicle. In addition, the amount of energy required for temperature rise can be reduced.

  When the target output required for the fuel cell system 100 is less than X1 shown in FIG. 16, the temperature of the stack 11 is raised without operating the combustion burner 21. That is, at least one of oxygen excess rate control of the gas supplied to the cathode 11a and cell voltage control of the stack 11 is controlled, and the temperature of the fuel cell is raised to the target temperature with the combustion burner 21 stopped. . Therefore, the amount of energy consumed can be reduced.

  Furthermore, when controlling the cell voltage, the voltage value at a certain ratio to the voltage value at which the fuel cell output reaches a peak, for example, the cell voltage is controlled to be around 0.5 (V). The stack 11 can be efficiently heated to the target temperature.

[Description of Second Embodiment]
Next, a fuel cell system according to a second embodiment of the present invention will be described. FIG. 9 is a block diagram showing a configuration of a fuel cell system 100a according to the second embodiment of the present invention. In contrast to the configuration of the first embodiment described above, the fuel cell system 100a according to the second embodiment includes a second-stage stack 32 having a cathode 32a and an anode 32b at the rear stage of the stack 11 (first-stage stack). The flow path connecting the provided point and the cathode 11a outlet of the first stage stack (first fuel cell) 11 and the cathode 32a inlet of the second stage stack (second fuel cell) 32 is cooling air introduction. It is connected to a passage (bypass passage) 33 and is different in that a part of the air sent from the air blower 12 through the cooling air introduction passage 33 is introduced to the cathode 32a. The cooling air introduction passage 33 is provided with a cooling air flow rate control device 34 for adjusting the amount of air introduced into the cathode 32a.

  The second stack 32 is provided with an inlet temperature sensor 51a for measuring the temperature on the inlet side, an outlet temperature sensor 51b for measuring the temperature on the outlet side, and a current / voltage sensor 52 for measuring the output current and voltage. It has been. Since the other configuration is the same as the configuration shown in FIG. 1, the same reference numerals are given and description of the configuration is omitted.

[Description of Operation of Second Embodiment]
Next, the operation of the fuel cell system 100a according to the second embodiment will be described with reference to the flowcharts shown in FIGS. FIG. 10 is a flowchart showing the entire processing procedure of the stack temperature raising operation when the fuel cell system 100a according to the second embodiment of the present invention is started.

  First, in step S101, the control unit 31 determines whether or not the first-stage stack 11 is to be activated. If activated (YES in step S101), in step S102, the control unit 31 is the combustion burner. It is determined whether or not the heating of the first stage stack 11 by 21 has been completed. If the heating has not been completed (NO in step S102), in step S103, the control unit 31 continuously controls the heating of the first stack 11 by the combustion burner 21. Details of the stack heating control are the same as those in the flowchart shown in FIG. Thereafter, the process proceeds to step S104.

  In step S104, the control unit 31 determines whether or not the temperature increase control of the first stage stack 11 has been completed. If the temperature increase control has not ended (NO in step S104), the control unit 31 performs temperature increase control of the first stack 11 in step S105. The temperature increase control of the first stage stack 11 is the same process as the flowchart shown in FIG. Thereafter, the process proceeds to step S106.

  In step S <b> 106, the control unit 31 determines whether or not the first temperature increase control of the second-stage stack 32 is necessary. The first temperature rise control is control for raising the temperature until the second-stage stack 32 reaches the power generation possible temperature. If the second-stage stack 32 has not reached the power generation possible temperature and the first temperature increase control is necessary (YES in step S106), in step S107, the control unit 31 determines that the second-stage stack 32 32 1st temperature increase control is performed. Details of the first temperature rise control will be described later with reference to FIG.

  On the other hand, when the first temperature increase control is not necessary (NO in step S106), or when the first temperature increase control is completed, in step S108, the control unit 31 performs the second temperature increase control of the second stack. It is determined whether or not is necessary. Here, the second temperature raising control is a control for raising the temperature to the temperature during normal operation after the second-stage stack 32 reaches the power generation possible temperature. If the second-stage stack 32 has not reached the temperature during normal operation and the second temperature increase control is necessary, the control unit 31 determines that the second-stage stack 32 has a second temperature control in step S109. Execute temperature rise control. Details of the second temperature rise control will be described later with reference to FIG.

  If the second temperature increase control is not necessary (NO in step S108), or if the second temperature increase control is completed, this process is terminated.

  Next, the processing procedure of the first temperature rise control for the second stack 32 shown in step S107 of FIG. 10 will be described with reference to the flowchart shown in FIG. First, in step S111, the control unit 31 reads a target output (total target output of the first stage stack 11 and the second stage stack 32) stored in a memory (not shown) or the like.

  In step S112, the control unit 31 determines whether or not the target output can be obtained by the operation of only the first stage stack 11. If possible (YES in step S112), in step S116, the control unit 31 turns on the first temperature increase control unnecessary determination flag of the second-stage stack 32.

  On the other hand, if not possible (NO in step S112), in step S113, the control unit 31 uses the inlet temperature sensor 51a and the outlet temperature sensor 51b provided in the second stage stack 32 to control the temperature of the second stage stack 32. (For example, an average value of the inlet temperature and the outlet temperature) is detected.

  In step S114, the control unit 31 determines whether or not the second stage stack 32 needs to be heated. That is, when the temperature of the second stack 32 has reached the power generation possible temperature in the process of step S113, the first temperature increase control is not necessary, and the process proceeds to step S116. On the other hand, if the power generation possible temperature has not been reached, the first temperature rise control is necessary, so the process proceeds to step S115.

  In step S115, the control unit 31 performs burner and oxygen excess rate control [3]. Details of this control will be described later with reference to the flowchart shown in FIG.

  Next, a detailed processing procedure of the burner and oxygen excess rate control [3] shown in step S115 of FIG. 11 will be described with reference to the flowchart shown in FIG.

  First, in step S121, the control unit 31 detects a temperature difference ΔT (outlet temperature) between the inlet temperature measured by the inlet temperature sensor 41a provided in the first stack 11 and the outlet temperature measured by the outlet temperature sensor 41b. -Inlet temperature) is detected. Alternatively, the outlet temperature of the cathode 11a is detected.

  In step S122, the control unit 31 calculates these differences from the relationship between the target output and the current output of the first-stage stack 11.

  In step S123, the control unit 31 determines whether it is necessary to start the combustion burner 21 based on the difference value obtained in the process of step S122. That is, when the difference value is larger than a certain value, it is determined that the combustion burner 21 needs to be started. If it is determined that it is necessary to start the combustion burner 21 (YES in step S123), the process proceeds to step S124. If it is determined that it is not necessary (NO in step S123), the process proceeds to step S124. The process proceeds to S130.

  In step S124, the control unit 31 reads the target outlet temperature of the combustion burner 21. In this process, the target outlet temperature stored in the memory or the like is read and acquired. Specifically, as shown in FIG. 17, a characteristic curve indicating the relationship between the difference value (difference between the target output and the current output) and the outlet temperature of the combustion burner 21 is stored, and is obtained by the process of step S122. By applying the difference value to the characteristic curve of FIG. 17, the outlet temperature of the combustion burner 21 is acquired.

  In step S125, the controller 31 supplies the excess oxygen combustion gas amount supplied to the cathode 11a of the first stack 11, that is, the flow rate of excess oxygen gas discharged after combustion in the combustion burner 21 (hereinafter referred to as “supply gas amount”). "). And it controls so that it may become this supply gas amount.

  Specifically, when the temperature difference ΔT is detected in the process of step S121, the supply gas amount is increased by a predetermined amount when ΔT> 0, and the supply gas amount is increased by a predetermined amount when ΔT <0. By decreasing, the temperature difference ΔT is controlled to approach zero. When the outlet temperature is detected in step S121, the supply gas amount is increased by a predetermined amount when (exit temperature)> (target temperature), and the supply gas when (exit temperature) <(target temperature). By reducing the amount by a predetermined amount, control is performed so that the temperature of the first stage stack 11 becomes the target temperature.

  In step S126, the control unit 31 calculates the required cathode air amount to be sent from the air blower 12 based on the supply gas amount obtained in the process of step S125. That is, the amount of gas supplied from the air blower 12 to the second-stage stack 11 via the combustion burner 21 and the first-stage stack 11 becomes the supply gas quantity obtained in the process of step S125. Then, the amount of air sent out by the air blower 12 is calculated.

  In step S127, the control unit 31 calculates the required fuel amount of the combustion burner 21 required to obtain this temperature based on the target outlet temperature of the combustion burner 21 acquired in the process of step S124. That is, when the temperature of the second-stage stack 32 has not reached the power generation possible temperature, the higher the target output required for the system, the higher the combustion gas temperature output from the combustion burner 21 is controlled.

  In step S128, the control unit 31 sets the amount of air obtained in the process of step S126 as the amount of air supplied to the cathode 11a, and further sets the amount of fuel supplied to the combustion burner 21 in step S129. The air blower 12 and the second fuel pump 22 are controlled so that the air amount and the fuel amount become the same.

  On the other hand, when it is not necessary to start the combustion burner 21 (NO in step S123), in step S130, the control unit 31 calculates the required cathode air amount sent from the air blower 12 based on the target output. In this process, the process similar to the process shown in step S125 is performed with the combustion burner 21 stopped.

  That is, when the temperature difference ΔT is detected in the process of step S121, the supply gas amount (corresponding to the oxygen amount) is increased by a predetermined amount when ΔT> 0, and the supply gas amount is increased when ΔT <0. By reducing the temperature by a predetermined amount, the temperature difference ΔT is controlled to approach zero. If the outlet temperature is detected in step S121, the amount of supplied gas (corresponding to the amount of oxygen) is increased by a predetermined amount when (outlet temperature)> (target temperature), and (outlet temperature) <(target temperature). ), The temperature of the first-stage stack 11 is controlled to be the target temperature by reducing the supply gas amount by a predetermined amount.

  Further, in step S131, the control unit 31 sets the amount of air sent from the air blower 12 so as to be the amount of air obtained in the process of step S130.

  Thus, by controlling the amount of gas supplied to the cathode 11a of the first stage stack 11 and the amount of fuel supplied to the combustion burner 21 based on the oxygen excess rate, the second stage stack from the cathode 11a of the first stage stack 11 is controlled. Since the gas flow rate at substantially the same temperature as the first-stage stack operating temperature flowing into the 32 cathodes 32a increases, the temperature can be quickly raised to the target temperature (power generation possible temperature).

  Next, a detailed processing procedure of the second temperature rise control of the second stack 32 shown in step S109 of FIG. 10 will be described with reference to the flowchart shown in FIG. First, in step S141 in FIG. 13, the control unit 31 calculates a target output required for the system from, for example, an accelerator operation amount in a vehicle-mounted system, and reads the result as a target output. .

  In step S142, the control unit 31 detects the current output of the fuel cell system 100a. The current output can be obtained based on the output current and voltage detected by the current / voltage sensor 42 provided in the first-stage stack 11 and the current / voltage sensor 52 provided in the second-stage stack 32. Further, a difference between the target output and the current output is obtained, and this is set as a difference value A. Thereafter, in step S143, the control unit 31 detects the temperature of the second stack 32. In this process, the stack temperature is detected as an average value, for example, by the inlet temperature sensor 51a and the outlet temperature sensor 51b provided in the second stage stack 32.

  In step S144, the control unit 31 determines whether or not the temperature of the second stack 32 needs to be increased. For example, if the temperature of the second stack 32 is equal to or higher than a predetermined value, the target output can be generated even if the difference value A is equal to or higher than the predetermined value. It is determined that there is no need to raise the temperature of the stage stack 32. If it is determined that it is necessary (“required” in step S144), the process proceeds to step S145. If it is determined that it is not necessary (“unnecessary” in step S144), the process proceeds to step S155. Proceed.

  In step S145, the control unit 31 determines whether or not the output of the second stack 32 has reached the target output. If the target output has been reached (YES in step S145), the process proceeds to step S149. If not reached (NO in step S145), the process proceeds to step S147.

  In steps S147 and S148, the control unit 31 reads the target cell voltage of the second-stage stack 32 from a memory or the like, controls the cell voltage to a predetermined value, and increases as the operating temperature of the second-stage stack 32 increases. The power generation output to be controlled is controlled to reach the target output. This processing is performed in the same manner as steps S33 and S34 in FIG. If this process ends, the process proceeds to step S151.

  On the other hand, when the output of the second-stage stack 32 reaches the target output (YES in step S145), in step S149, the control unit 31 outputs so that the output of the second-stage stack 32 maintains the target output. The current is controlled, and the target output determination flag is turned on in step S150.

  That is, in the processing of steps S145 to S150, if the output of the second stage stack 32 has not reached the target output, the second stage stack 32 can be raised in temperature by performing cell voltage control, and the target output is obtained. If it has reached, there is no need to increase the output any more, so the flag indicating that the target output has been reached is turned on without performing the cell voltage control.

  In step S151, the control unit 31 determines whether or not the temperature of the second stage stack 32 has reached the target temperature (the temperature during normal operation of the second stage stack 32). (NO in step S151), the process proceeds to step S152. If the target temperature has been reached (YES in step S151), the process proceeds to step S153.

  In step S152, the control unit 31 performs oxygen excess rate control [3]. Details of this control will be described later with reference to the flowchart shown in FIG.

  In step S153, the control unit 31 turns on a target temperature arrival determination flag indicating that the temperature of the second-stage stack 32 has reached the target temperature. Thereafter, the process proceeds to step S154.

  In step S154, the control unit 31 determines whether or not the second-stage stack 32 has reached the target temperature and the target output, and if so (YES in step S154), proceeds to step S155, and then This process is terminated. If not reached (NO in step S154), the process is terminated.

  Next, a detailed processing procedure of the excess oxygen ratio control [3] shown in step S152 of FIG. 13 will be described with reference to the flowchart shown in FIG. First, in step S161 in FIG. 14, the control unit 31 calculates the amount of oxygen in the gas output from the first stack 11. This calculation can be obtained from the relationship between the amount of oxygen supplied to the first stage stack 11 and the amount of oxygen used for power generation.

  In step S <b> 162, the control unit 31 reads the target minimum oxygen excess rate of the second-stage stack 32. This process is acquired by reading a numerical value stored in a memory (not shown), for example.

  In step S <b> 163, the control unit 31 detects the output current of the second stack 32 by the current / voltage sensor 52.

  In step S164, the control unit 31 calculates the required minimum oxygen amount of the second stack 32. In this process, based on the output current detected in the process of step S163, the amount of oxygen necessary to generate this current (minimum required oxygen amount) is obtained, and this oxygen amount is obtained in the process of step S162. The minimum oxygen amount is obtained by multiplying the target minimum oxygen excess rate. At this time, since the oxygen excess rate read in the process of step S161 is set to a value lower than the oxygen excess rate during normal operation, the minimum oxygen amount is lower than the minimum oxygen amount during normal operation. .

  In step S165, the control unit 31 determines the minimum oxygen amount obtained in the process in step S164 and the oxygen amount in the gas output from the first-stage stack 11 obtained in the process in step S161 (second-stage supply oxygen amount). And compare. When the second-stage supply oxygen amount is larger than the minimum oxygen amount (YES in step S165), the process proceeds to step S166, and the second-stage supply oxygen amount is smaller than the minimum oxygen amount. (NO in step S165), the process proceeds to step S167.

  In step S166, the control unit 31 sets the cooling air flow rate supplied to the second stack 32 from the cooling air flow rate control device 34 shown in FIG. 9 to zero. That is, when the minimum oxygen amount required by the second stage stack 32 is smaller than the oxygen amount contained in the gas delivered from the first stage stack 11, the oxygen required for power generation by the second stage stack 32 is less. Therefore, the cooling air from the air blower 12 is not supplied.

  In step S 167, the control unit 31 calculates the cooling air flow rate supplied to the second-stage stack 32 from the cooling air flow rate control device 34. That is, when the minimum oxygen amount required by the second stage stack 32 is larger than the oxygen amount (second stage supply oxygen amount) contained in the gas delivered from the first stage stack 11, the second stage Since the oxygen required for power generation of the stack 32 is insufficient, the amount of cooling air to be supplied from the cooling air flow rate control device 34 is obtained.

  In step S168, the control unit 31 requests the added value of the air supplied to the first stage stack 11 and the air sent from the cooling air flow rate control device 34 to the first stage stack 11 and the second stage stack 32. Calculated as the sum of the air volume

  In step S169, the control unit 31 sets the amount of air supplied to the cathode 32a of the second-stage stack 32. Thereafter, in step S170, the opening degree of the cooling air flow rate control device 34 is adjusted to control the amount of cooling air supplied to the cathode 32a to a desired numerical value. In this way, the amount of oxygen supplied to the cathode 32a of the second-stage stack 32 is controlled so as not to be less than or equal to the minimum amount of oxygen multiplied by the oxygen excess rate, and the amount of oxygen necessary for power generation is reduced. By reducing the cooling effect of the second stage stack 32, the temperature of the second stage stack 32 can be increased immediately.

  Thus, in the fuel cell system according to the second embodiment, when the first-stage stack 11 and the second-stage stack 32 are connected in series with each other, the combustion is performed when the second-stage stack 32 is started. Since at least one of control of the amount of combustion gas delivered from the burner 21, control of the oxygen excess rate, and control of the cell voltage within a predetermined range is performed, the target output of the second stage stack 32 can be quickly achieved. The power generation by the second stack 32 can be started quickly.

  When the temperature of the second stack 32 has not reached the power generation possible temperature, the higher the target output required for the system, the higher the temperature of the combustion gas output from the combustion burner 21 (oxidant heating means). Since control is performed so as to increase, the combustion gas output from the combustion burner 21 flows into the cathode 32a of the second-stage stack 32 via the first-stage stack 11, so that the second-stage stack 32 is quickly heated. This can further reduce the time required to reach the target temperature.

  Further, when the temperature of the second stage stack 32 has reached the power generation possible temperature, the heating by the combustion burner 21 is stopped, and the oxygen excess rate supplied to the second stage stack 32 is set low, or Since at least one of the controls for setting the cell voltage of the second-stage stack 32 within a predetermined range is performed, the amount of fuel required to burn the combustion burner 21 can be reduced, and energy consumption can be reduced. .

  Further, a cooling air introduction passage 33 is connected to a flow path connecting the cathode 11a outlet of the first-stage stack 11 and the cathode 32a inlet of the second-stage stack 32, and the air is passed through the cooling air introduction passage 33. Since a part of the air sent from the blower 12 is introduced into the cathode 32a, the minimum oxygen amount required at the cathode 32a of the second-stage stack 32 can be ensured reliably.

[Description of Third Embodiment]
Next, a third embodiment of the present invention will be described. FIG. 18 is an explanatory diagram showing a state in which the fuel cell system 100 according to the third embodiment is connected to the external load 61, and the fuel cell system 100 and the external power source 62 pass through the relay device 63. The power is supplied to the external load 61. Then, the fuel cell system 100 sets a target output and a target temperature according to the required power of the external load 61. The fuel cell system 100 has the configuration shown in FIG.

  The operation of the fuel cell system according to the third embodiment will be described below with reference to the flowchart shown in FIG. First, in step S201, the control unit 31 (see FIG. 1) of the fuel cell system 100 detects the required power of the external load 61.

  In step S <b> 202, the control unit 31 obtains the generated power of the stack 11. Next, in step S203, a difference value between the external load required power and the generated power of the stack 11 is calculated.

  In step S204, the control part 31 sets a target output and target temperature based on the difference value calculated | required by the process of step S203.

  That is, the difference value between the external load required power and the generated power of the stack 11 is supplied from the external power source 62. Therefore, in order to supplement the power supplied by the external power source 62, the difference value is set according to the difference value. Set the target output and target temperature.

  Thus, in the fuel cell system according to the third embodiment, the shortage of the power supplied by the external power source 62 is calculated as a difference value, and the target output of the stack 11 is controlled to vary according to this difference value. According to the power required by the external load 61, the power generation amount can be changed immediately and supplied to the external load 61. Therefore, the temperature increase rate of the stack 11 is controlled as necessary, and the amount of energy required for the temperature increase control can be reduced.

[Description of Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. FIG. 20 is an explanatory diagram showing a state in which the fuel cell system 100 according to the fourth embodiment is connected to the external load 61, and power is supplied to the external load 61 by the fuel cell system 100 and the power storage device 64. It is supposed to be configured. Then, the fuel cell system 100 sets a target output and a target temperature according to the required power of the external load 61 and the amount of power stored in the power storage device 64. The fuel cell system 100 has the configuration shown in FIG.

  The operation of the fuel cell system according to the fourth embodiment will be described below with reference to the flowchart shown in FIG. First, in step S211, the control unit 31 (see FIG. 1) of the fuel cell system 100 detects the required power of the external load 61.

  In step S <b> 212, the control unit 31 detects a stored amount ratio (SOC; State Of Charge) of the power storage device 64. Furthermore, in step S213, the control unit 31 sets the target output and target temperature of the fuel cell system 100. This process can be set using the map shown in FIG. That is, FIG. 22 is a map showing the relationship between the SOC and the required external load power, and the target output and target temperature of the stack 11 are set based on this map.

  Thus, in the fuel cell system according to the fourth embodiment, the target output of the stack 11 is controlled so as to vary according to the stored amount ratio (SOC) of the power storage device 64, so that the power required by the external load 61 is reduced. Accordingly, the power generation amount can be immediately changed and supplied to the external load 61. Therefore, the temperature increase rate of the stack 11 is controlled in accordance with the charged amount ratio of the power storage device 64, and the amount of energy required for the temperature increase control can be reduced.

[Description of Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. FIG. 23 is an explanatory diagram showing a state in which the fuel cell system 100 according to the fifth embodiment is connected to, for example, an external load 61 (in this embodiment, a vehicle motor). The power is supplied to the external load 61 by the power storage device 64.

  The fuel cell system 100 is configured to be able to acquire data on the moving speed and moving direction of a vehicle from a control device mounted on the vehicle. Then, the fuel cell system 100 estimates a required output after a predetermined time based on the moving direction and moving speed of the vehicle, and based on the estimated required output and the charged amount ratio (SOC) of the power storage device 64, the fuel cell system. A target output or target temperature of 100 is set.

  The operation of the fuel cell system according to the fifth embodiment will be described below with reference to the flowchart shown in FIG. First, in step S231, the control unit 31 (see FIG. 1) of the fuel cell system 100 acquires position information (including altitude information) of the vehicle on which the fuel cell system 100 is mounted. This position information can be acquired from GPS information of a navigation system mounted on the vehicle, for example.

  In step S232, the control unit 31 calculates the moving direction of the vehicle. Further, in step S233, the moving speed of the vehicle is detected.

  In step S234, the control unit 31 estimates a required output after a predetermined time based on the moving speed and moving direction of the vehicle.

  In step S235, control unit 31 detects the power storage ratio (SOC) of power storage device 64.

  In step S236, the control unit 31 sets a target output or a target temperature based on the SOC value. At this time, the target output or target temperature is set as time-series data as shown in FIG. This process can be set using the map shown in FIG. 26 is a map showing the relationship between the SOC and the estimated output, and the target output and target temperature of the stack 11 are set based on this map.

  By doing so, the target temperature and target output of the fuel cell system 100 when the vehicle is traveling can be acquired as time-series data corresponding to the traveling state of the vehicle, and the flexibility according to the traveling state is high. Electric power can be supplied.

  Thus, in the fuel cell system according to the fifth embodiment, the temperature increase rate of the stack 11 is controlled in accordance with the target output and target temperature after a predetermined time estimated by GPS information or the like. The temperature rise control can be performed at a time earlier than the time when the temperature is required, and the energy consumption required for the temperature rise control can be reduced.

  Although the fuel cell system of the present invention has been described based on the illustrated embodiment, the present invention is not limited to this, and the configuration of each part is replaced with an arbitrary configuration having the same function. Can do.

  For example, in each of the above-described embodiments, an example of a fuel cell system for in-vehicle use has been described. However, the present invention is not limited to in-vehicle use, and is used for other uses such as a fuel cell for general household use. It is also possible.

  The present invention can be used to quickly raise the stack temperature to the temperature at the target operation.

11 stacks, 1st stack (fuel cell stack)
11a cathode 11b anode 12 air blower 13 heat exchanger 14 first fuel pump 15 heat exchange type pre-reformer 16 pre-reformer 17 combustor 19, 20 flow control device 21 combustion burner 22 second fuel pump 23 anode off-gas circulation Unit 25 Evaporator 31 Control unit 32 Second stage stack 32a Cathode 32b Anode 33 Cooling air introduction passage 34 Cooling air flow rate control device 41a Inlet temperature sensor 41b Outlet temperature sensor 42 Current / voltage sensor 51a Inlet temperature sensor 51b Outlet temperature sensor 52 Current Voltage sensor 61 External load 62 External power supply 63 Relay device 64 Power storage device 100, 100a Fuel cell system

Claims (8)

A fuel cell in which reformed gas is supplied to the anode and oxidant is supplied to the cathode to generate electricity;
An oxidant supply means provided upstream of the cathode and for supplying an oxidant to the cathode;
An oxidant heating means that is provided between the oxidant supply means and the cathode and heats the oxidant output from the oxidant supply means;
At the start of the fuel cell, wherein the heated oxidant with oxidant heating means is supplied to the cathode by elevating the temperature of the fuel cell, after the fuel cell has reached the power generation possible temperature of the fuel cell When the target output is less than or equal to the preset predetermined value X1, both of the following (a) and (b) are performed until the fuel cell reaches the predetermined target output or the target temperature, and the target output is Control means for implementing the following (b) and at least one of (a) and (c) until the fuel cell reaches a predetermined target output or target temperature when the predetermined value X1 is exceeded ; A fuel cell system comprising:
(A) Control for setting the oxygen excess rate of the oxidant output from the oxidant heating means to be lower than the oxygen excess rate at the target output of the fuel cell (b) per unit area of the cell of the fuel cell Control for setting a cell voltage when the output reaches a peak, and setting the cell voltage so as to be close to the cell voltage (c) Heating control by the oxidant heating means The predetermined value X1 is a target at the point where the characteristic curve of the target output and input energy when the oxidant heating means is off intersects the characteristic curve of the target output and input energy when the oxidant superheating means is on. The fuel cell system according to claim 1, wherein the fuel cell system is an output . A fuel cell in which reformed gas is supplied to the anode and oxidant is supplied to the cathode to generate electricity;
An oxidant supply means provided upstream of the cathode and for supplying an oxidant to the cathode;
An oxidant heating unit that is provided between the oxidant supply unit and the cathode and heats the oxidant output from the oxidant supply unit;
The fuel cell includes a first fuel cell and a second fuel cell arranged in series downstream of the first fuel cell, and further includes control means for controlling the first fuel cell and the second fuel cell. And
The control means includes
When starting the first fuel cell, the oxidant heated by the oxidant heating means is supplied to the cathode to control the temperature of the first fuel cell,
Further, when the second fuel cell is started after the first fuel cell is operated under an operating condition corresponding to a target output required for the system, the second fuel cell has a predetermined target output or target Depending on the target power required for the system and the temperature of the second fuel cell until the temperature is reached,
Control for setting the oxygen excess rate of the oxidant supplied to the cathode of the second fuel cell to be lower than the oxygen excess rate at the target output of the second fuel cell;
And a control for setting a cell voltage so that the output per unit area of the cell of the fuel cell reaches a peak and setting the cell voltage to be close to the cell voltage,
And heating control by the oxidant heating means,
A fuel cell system performing at least one of the controls. When the second fuel cell has not reached the power generation possible temperature, the control means increases the oxidant temperature output from the oxidant heating means as the target output required for the system increases. The fuel cell system according to claim 3 , wherein the fuel cell system is controlled. When the target output or target temperature required for the second fuel cell is higher than the current output or temperature after the second fuel cell reaches the power generation possible temperature ,
Control for setting the oxygen excess rate of the oxidant supplied to the cathode of the second fuel cell to be lower than the oxygen excess rate at the target output of the second fuel cell, and the output voltage of the second fuel cell in a predetermined range 4. The fuel cell system according to claim 3, wherein at least one of the internal control is performed, and the heating control by the oxidant heating means is stopped . A bypass flow path for introducing a part of the oxidant sent from the oxidant supply means is provided in a flow path between the cathode outlet of the first fuel cell and the cathode inlet of the second fuel cell; 6. The oxidant is introduced from the bypass channel to the cathode of the second fuel cell when the oxidant required by the second fuel cell is insufficient. 2. The fuel cell system according to item 1 . The control means includes a target output or a target temperature required for the fuel cell, a required power of an external load to which the fuel cell is connected, an output power of an external power source that supplies power to the external load in a separate system, The fuel cell system according to any one of claims 1 to 6, wherein the fuel cell system is set to have a difference value of . When the storage amount ratio and the estimated output are determined, a map for determining the target output or target temperature corresponding to this is set in advance,
The control means requests the fuel cell by applying an estimated output of an external load to which the fuel cell is connected and a storage amount ratio of a storage battery that supplies power to the external load in a separate system to the map. Setting the target output or target temperature
The fuel cell system according to any one of claims 1 to 6 , wherein:

Images