JP2012003910A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance restraint effectiveness of catalyst deterioration after taking steps of charging into a secondary cell.SOLUTION: A fuel cell system 10 controls the operation of a fuel cell 100 for charging of surplus generated power into a secondary cell not so as to exceed a high-potential avoidance voltage specifying an upper limit of output power, while maintaining a temperature of the fuel cell 100 so that the FC temperature of the fuel cell 100 is accommodated in a target temperature range. When the secondary cell charging capacity is on the full charging side, the high-potential avoidance voltage is shifted to the high-voltage side and a target temperature range for maintaining the FC temperature is shifted to the low temperature side.

Description

  The present invention relates to a fuel cell system having a secondary battery.

  The fuel cell generates electric power by subjecting the supplied reaction gas to an electrochemical reaction under the catalyst, and drives the load with the generated electric power. Since the generated power of the fuel cell is insufficient or excessive when driving the load, the secondary battery is used in combination with the fuel cell, and the secondary battery compensates for the power shortage while charging the generated power of the fuel cell. Fuel cell systems are in practical use. Since the deterioration of the function of the catalyst causes a decrease in the power generation performance, suppression of the deterioration of the catalyst function is required, and various proposals have been made (for example, Patent Document 1).

JP 2007-129647 A JP 2007-122897 A

  In Patent Document 1, the high potential avoidance voltage that determines the upper limit of the output power of the fuel cell is variably set according to the state of charge of the secondary battery, so that the charge of the secondary battery can be dealt with while the catalyst has a high potential. The catalyst is prevented from being deteriorated by being exposed to the catalyst. On the other hand, in Patent Document 2, the catalyst temperature is lowered by supplying a low-temperature gas to the fuel cell when the operating state of the fuel cell changes from a high load to a low load, thereby suppressing catalyst deterioration.

  However, even if the high potential avoidance voltage is variably set according to the charging state of the secondary battery as proposed in Patent Document 1, the temperature of the fuel cell rises regardless of the setting state of the high potential avoidance voltage. Therefore, it has been required to take measures to suppress catalyst deterioration in such a situation. By the way, Patent Document 2 proposes a countermeasure for suppressing catalyst deterioration by suppressing the temperature rise of the fuel cell by supplying a low-temperature gas, but is a countermeasure when the operating state is in a transition period. The situation is that it is not sufficient as a countermeasure after charging the battery in a system including a secondary battery.

  The present invention has been made in order to solve at least a part of the above-described problems, and an object of the present invention is to improve the effectiveness of suppressing catalyst deterioration after charging a secondary battery.

  In order to achieve at least a part of the above object, the present invention adopts the following configuration.

[Application 1: Fuel cell system]
A fuel cell system,
A fuel cell that generates power by receiving a supply of a reactive gas; and
Battery temperature detecting means for detecting the temperature of the fuel cell;
Battery temperature maintaining means for maintaining the temperature of the fuel cell so that the battery temperature detected by the battery temperature detecting means falls within a target temperature range;
Control means for controlling the operation of the fuel cell so that the output power of the fuel cell does not exceed a predetermined high potential avoidance voltage as an upper limit thereof;
A secondary battery that exchanges power with the fuel cell;
Charge detection means for detecting a charge capacity in the secondary battery;
If the charge capacity detected by the charge detection means is a full charge side, in addition to a voltage shift setting for shifting the high potential avoidance voltage to the high voltage side, a temperature shift setting for shifting the target temperature range to the low temperature side is set. A setting means for executing,
This is the gist.

  In the fuel cell system having the above configuration, if the detected charge capacity of the secondary battery is on the full charge side, the high potential avoidance voltage that determines the upper limit of the output power of the fuel cell is shifted to the high voltage side, and the target temperature range is Shift to lower temperature. For this reason, the catalyst that the fuel cell has for causing the reaction of the reaction gas has only an opportunity to be exposed to a high potential in a low temperature environment shifted to a low temperature side, so that it is possible to suppress catalyst deterioration. it can. Moreover, under the situation where the detection charge capacity of the secondary battery is on the fully charged side, the necessity for charging the secondary battery is low, and the fuel cell has a high potential avoidance voltage whose output voltage has shifted to the high voltage side. Since the operation is controlled so as not to exceed, the operation control range is expanded. Therefore, the fuel cell can be operated so as not to generate surplus electric power, or can be operated so as to cope with battery charging that is less necessary, so that it is possible to cope with charging of the secondary battery.

  On the other hand, when the detection charge capacity of the secondary battery is not the fully charged side and the supplementary charging to the secondary battery is necessary, the voltage shift setting to the high voltage side and the temperature shift setting to the low temperature side described above. Is not made. Therefore, since the catalyst of the fuel cell is not exposed to a high potential in an environment that has not shifted to the low temperature side, catalyst deterioration can be suppressed. In addition, since the high potential avoidance voltage is not shifted to the high voltage side, the operation control width of the fuel cell is narrowed, and the chances of surplus power generation are increased. Therefore, the surplus power can be applied to supplementary charging of the secondary battery, and the secondary battery can be charged.

  The fuel cell system described above can be configured as follows. For example, a form change maintenance rate is introduced, and the correlation between this form change maintenance rate and the output voltage of the fuel cell is stored for each temperature of the fuel cell. This form change maintenance rate represents the status of maintaining the catalytic function of the catalyst of the fuel cell, and decreases as the output voltage of the fuel cell increases. After storing the above correlation, the voltage shift can be executed with reference to the correlation corresponding to the temperature in the target temperature range. In this way, the high potential avoidance voltage can be shifted to the high voltage side more reliably while maintaining the catalytic function.

  In this case, if the high potential avoidance voltage is shifted to the output voltage on the high voltage side corresponding to the lower limit form change maintenance rate, which is the lower limit in maintaining the catalyst function, the effectiveness of maintaining the catalyst function and the high potential avoidance voltage are increased. It is possible to increase the effectiveness of the high voltage side shift. Then, a high potential avoidance voltage is applied to the output voltage on the high voltage side corresponding to the high form change maintenance ratio, which is a form change maintenance ratio higher than the lower limit form change maintenance ratio and causes inflection in the correlation of the form change maintenance ratio. May be shifted. In this way, the above-described effectiveness can be further enhanced.

  Further, if the detected battery temperature is a temperature deviating from the target temperature range to the lower temperature side, the temperature shift setting and the voltage shift setting can be executed regardless of the state of the charge capacity. This has the following advantages.

  When the battery temperature is low, since the fuel cell operation is often performed under a low outside air temperature condition, the temperature is low not only in the fuel cell but also in the secondary battery, and the capacity of the secondary battery is reduced. I can get up. In this case, if the high potential avoidance voltage is low, the operation control width of the fuel cell is narrowed as described above, and the opportunity for surplus power generation increases. It can be too much. However, in the above embodiment, since the high potential avoidance voltage is shifted to the high voltage side, surplus power is less likely to be generated, charging of the secondary battery is slowed down, and surplus power can be suppressed. In addition, since the temperature of the fuel cell is also low, catalyst deterioration can be suppressed.

It is explanatory drawing which shows schematic structure of the fuel cell system as an Example of this invention. It is a flowchart which shows the temperature potential setting process which the fuel cell system 10 of a present Example performs. It is explanatory drawing which shows the correlation with the form change maintenance factor showing the condition of the catalyst function maintenance of the catalyst which the fuel cell has in each cell, and the output voltage of a fuel cell.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic configuration of a fuel cell system as an embodiment of the present invention. The fuel cell system 10 includes a fuel cell 100, a secondary battery 200, a fuel gas supply system 300, an oxidizing gas supply system 400, a cooling system 500, a DC-DC converter 600, a cell monitor 620, a control unit. 700. The fuel cell system 10 supplies power to the load 610. The fuel cell 100 has a stack structure in which a plurality of single cells (not shown) are stacked. A cell monitor 620 is connected to each single cell, and the state of each single cell, for example, voltage and current can be monitored. Further, a temperature sensor 110 is connected to the fuel cell 100, and the sensor detects the temperature of the fuel cell 100 and outputs the detected temperature (fuel cell temperature) to the control unit 700.

  The fuel gas supply system 300 supplies hydrogen as a fuel gas used for an electrochemical reaction in the fuel cell 100. The fuel gas supply system 300 includes a fuel gas tank 310, a cutoff valve 320, and a regulator 330. The shut-off valve 320 is shut off when the fuel cell system 10 is stopped, and stops the supply of hydrogen gas. The regulator 330 adjusts the pressure of hydrogen supplied from the fuel cell 100.

  The oxidizing gas supply system 400 supplies air as an oxidizing gas used for an electrochemical reaction in the fuel cell 100. The oxidizing gas supply system 400 includes an air cleaner 410, an air pump 420, an intercooler 430, and a filter 440. The air cleaner 410 removes dust and dirt in the air when taking in air in the atmosphere. The air pump 420 compresses air and supplies it to the fuel cell 100. A motor 421 is connected to the air pump 420. The intercooler 430 cools air that has become hot due to compression. The filter 435 removes fine dust and dust that could not be removed by the air cleaner 410.

  The secondary battery 200 is connected to the fuel cell 100 via the DC-DC converter 600 and functions as an auxiliary power source for the fuel cell 100. That is, when the output of the fuel cell 100 does not satisfy the output request from the load 610, the secondary battery 200 compensates for the difference by outputting the difference. Conversely, when the output of the fuel cell 100 is larger than the output request of the load 610, the secondary battery 200 charges the difference. As the secondary battery 200, for example, a lead storage battery, a nickel metal hydride battery, a lithium ion battery, or the like can be adopted. A capacity detection sensor 210 is connected to the secondary battery 200, and the sensor detects the charging state of the secondary battery 200 and outputs the detected charge amount (hereinafter also referred to as SOC) to the control unit 700.

  The cooling system 500 circulates the refrigerant in a circulation path 520 including the fuel cell 100 and the radiator 510. The controller 700 sets a target temperature range of the battery temperature of the fuel cell 100 by a potential setting process or the like described later. Then, the control unit 700 controls the circulation of the refrigerant in the cooling system 500 while adjusting the refrigerant circulation amount by driving and controlling the circulation pump 530 so that the battery temperature detected by the temperature sensor 110 falls within the set target temperature range. Accordingly, the temperature of the fuel cell 100 (cell temperature) is maintained.

  The DC-DC converter 600 has a charging / discharging control function for controlling charging / discharging of the secondary battery 200, and controls charging / discharging of the secondary battery 200 in response to a control signal from the control unit 700, The voltage level applied to the load 610 is variably adjusted.

  For example, the control unit 700 is configured as a microcomputer including a main storage device and a central processing unit, and controls the gas supply amount in response to an output request from the load 610. For the fuel gas supply system 300, the regulator 330 is controlled to control the supply amount of the fuel gas. For the oxidizing gas supply system 400, the motor 421 is controlled to control the supply amount of the oxidizing gas. In addition, the control unit 700 controls the DC-DC converter 600 in response to an output request from the load 610.

  The control unit 700 includes a storage unit 710, and the storage unit stores a later-described form change maintenance rate that represents the state of maintenance of the catalyst function of a catalyst (for example, platinum catalyst) that the fuel cell 100 has in each cell.

  FIG. 2 is a flowchart showing a temperature potential setting process performed by the fuel cell system 10 of the present embodiment. This temperature potential setting process is repeatedly executed at predetermined time intervals by the control unit 700. The control unit 700 first determines the fuel cell temperature (FC temperature) and the secondary battery 200 from the temperature sensor 110 and the capacity detection sensor 210. The SOC is read (step S100). Next, it is determined whether or not the read FC temperature is lower than 40 ° C. (step S110).

  When the fuel cell 100 continues to operate properly, the FC temperature normally falls within the range of 60 to 80 ° C. That is, the control unit 700 sets the temperature range of 60 to 80 ° C. as a target temperature range, and cools the temperature sensor 110 so that the detected temperature falls within this target temperature range (60 to 80 ° C .; hereinafter, normal FC temperature range). The amount of refrigerant circulation in the system 500 (that is, the driving state of the circulation pump 530) is controlled. Thereby, as described above, the FC temperature is maintained in the normal FC temperature range of 60 to 80 ° C. However, when it is affirmed in step S110 that the FC temperature is lower than 40 ° C., since the FC temperature is larger than the normal FC temperature range and deviates to the low temperature side, the current environment of the fuel cell system 10 is the system Expected to be at the beginning of operation or under low outside air temperature conditions. Under such circumstances, the temperature of the secondary battery 200 is expected to be low, and the charging capacity is expected to be reduced. Therefore, the process proceeds to step S130 in order to deal with the capacity decrease. In addition, the case where it transfers to step S130 through the affirmation determination in step S110 is mentioned later.

  On the other hand, if the negative determination is made in step S110 that the FC temperature is 40 ° C. or higher, whether the SOC of the read secondary battery 200 exceeds 60% of the full charge, that is, whether the SOC is on the full charge side. Determination is made (step S120). If an affirmative decision is made here, the current charging capacity of the secondary battery 200 is on the fully charged side. In this case, the target temperature of the FC temperature is set to a low temperature within the normal FC temperature range (60 to 80 ° C.). Shift to the side, for example, 40 to 60 ° C. (step S130). Step S130, which has undergone an affirmative determination in step S120, is a process under the determination that the FC temperature is 40 ° C. or higher in step S110 before the transition to step S120. Therefore, the control part 700 changed the target temperature range to 40-60 degreeC by step S130 which passed negative determination (FC temperature> = 40 degreeC) in step S110, and affirmation determination (SOC> 60%) of step S120. Above, the circulation amount of the refrigerant circulation in the cooling system 500 (that is, the circulation pump 530) so that the temperature detected by the temperature sensor 110 falls within this target temperature range (40 to 60 ° C .; hereinafter, low temperature side shift temperature range). Control the driving situation). Specifically, the circulation pump 530 is controlled by increasing the refrigerant circulation amount so that the FC temperature (≧ 40 ° C.) falls within the changed low temperature side shift temperature range (40-60 ° C.). Note that the threshold for determination in step S120 is not limited to 60% of the full charge described above, and can be at least 50% or more of the full charge.

  Following such a low temperature side shift of the FC temperature target temperature, the control unit 700 sets the high potential avoidance voltage that determines the upper limit of the output power of the fuel cell 100 to the temperature in the target temperature range when maintaining the FC temperature, in this case. Is shifted to the high voltage side in correspondence with the temperature in the shifted low temperature side shift temperature range. In shifting the high potential avoidance voltage on the high voltage side, the control unit 700 first refers to the map of the form change maintenance rate stored in the storage unit 710 (step S140). FIG. 3 is an explanatory diagram showing the correlation between the form change maintenance rate representing the state of catalyst function maintenance of the catalyst that the fuel cell 100 has in each cell and the output voltage of the fuel cell.

  As shown in the figure, the shape change maintenance rate has a property of decreasing as the output voltage of the fuel cell 100 increases, and the correlation between the shape change maintenance rate and the output voltage of the fuel cell differs depending on the temperature. This form change maintenance rate is obtained from a potential variation endurance model test using the temperature and the upper limit potential as parameters after fixing the lower limit potential of the fuel cell 100. The storage unit 710 of the control unit 700 stores a correlation between the form change maintenance rate obtained in the potential fluctuation endurance model test and the output voltage of the fuel cell in a map for each temperature. In this embodiment, the battery operation at a form change maintenance rate of about 50%, in other words, the 50% form change maintenance rate is set to the lower limit so that the electrochemical reaction proceeds in the presence of the catalyst in each cell. To do. This lower limit maintenance rate (50%) assumes that the fuel cell system 10 including the fuel cell 100 is mounted on a vehicle, and the durability (target durability years) required for the fuel cell 100 of the system and the power generation performance maintenance ( The target performance degradation rate) is determined.

  Then, the output voltage on the high potential side corresponding to this lower limit maintenance rate is converted to a temperature in the target temperature range when maintaining the FC temperature (the temperature in the shifted low temperature side shift temperature range: 40 ° C.). Determine through reference. Referring to FIG. 3, the voltage Hv1 paired with the 50% lower limit form change maintenance rate is read from the form change maintenance rate map corresponding to 40 ° C., and the high potential avoidance voltage is set to this voltage Hv1 on the high potential side ( Shift) (step S150). Thereby, the control unit 700 controls the operation of the fuel cell 100 while adjusting the supply amounts of the fuel gas and the oxidizing gas so that the output voltage does not exceed the voltage Hv1.

  On the other hand, if it is determined in step S120 that the SOC of the secondary battery 200 is 60% or less of the full charge, the current charge capacity of the secondary battery 200 is not the full charge side, and the rechargeable charge to the secondary battery 200 is performed. There is a high need for. Therefore, in this case, the FC temperature target temperature is set (returned or maintained) in the normal FC temperature range (60 to 80 ° C.) (step S160). This step S160 after the negative determination of step S120 is a process under the determination that the FC temperature is 40 ° C. or higher in step S110 before the transition to step S120. Therefore, the control unit 700 performs normal FC having a target temperature range of 60 to 80 ° C. through the negative determination (FC temperature ≧ 40 ° C.) in step S 110 and the negative determination (SOC ≦ 60%) in step S 120. After setting the temperature range, the circulation amount of the refrigerant circulation in the cooling system 500 (that is, the circulation pump 530) so that the temperature detected by the temperature sensor 110 falls within this target temperature range (normally FC temperature range: 60 to 80 ° C.). To control the driving status). Specifically, if the target temperature range up to that point is the low temperature side shift temperature range, the normal FC temperature range (60 to 80 ° C.) after the FC temperature (≧ 40 ° C.) is changed due to the decrease in the refrigerant circulation rate The circulation pump 530 is controlled so as to be within the range. Further, if the target temperature range up to that point is already the normal FC temperature range, the refrigerant circulation rate is maintained so as not to change greatly so that the FC temperature falls within the changed normal FC temperature range (60 to 80 ° C.). The circulation pump 530 is controlled.

  Following the normal FC temperature range setting of the FC temperature target temperature, the process proceeds to the above-described step S140, where the map is referenced and the high potential avoidance voltage is set (step S150). In this case, when referring to the map in step S140, the control unit 700 refers to the map of the correlation between the form change maintenance rate and the voltage stored in the storage unit 710 for the temperature (80 ° C.) corresponding to the normal FC temperature range. Then, the high potential avoidance voltage is set (shifted) to the voltage Hv2 corresponding to the lower limit maintenance ratio (step S150). Thereby, the control unit 700 controls the operation of the fuel cell 100 while adjusting the supply amounts of the fuel gas and the oxidizing gas so that the output voltage does not exceed the voltage Hv2. In this case, since the fuel cell 100 is normally operated in the temperature range of the FC temperature range (60 to 80 ° C.), the voltage Hv2 corresponds to a high potential avoidance voltage that is commonly used in normal battery operation control. In step S150 following step S160, the high potential avoidance voltage is not shifted to the high potential side.

  In step S130 following the affirmative determination in step S110 (FC temperature <40 ° C.), as described above, the FC temperature target temperature is shifted to the low temperature side (40 to 60 ° C.), and then the high temperature is increased. The potential avoidance voltage is set (shifted) to the voltage Hv1 on the high potential side corresponding to the temperature and the lower limit maintenance ratio in the shifted low temperature side shift temperature range (step S150). Thereby, the control unit 700 maintains the FC temperature at 40 to 60 ° C., and adjusts the supply amounts of the fuel gas and the oxidizing gas so that the output voltage does not exceed the voltage Hv1, and operates the fuel cell 100. Control.

  In the fuel cell system 10 of the present embodiment described above, if the SOC of the secondary battery 200 is a full charge side exceeding 60% of the full charge (affirmative determination in step S120), the FC temperature target temperature is set to After shifting from the normal FC temperature range (60 to 80 ° C.) to the low temperature side temperature range (low temperature side shift temperature range: 40 to 60 ° C.) (step S130), a high value that determines the upper limit of the output power of the fuel cell 100 is set. The potential avoidance voltage is shifted to a high-potential-side voltage Hv1 corresponding to the lower limit of the change in form change of 50% and the shifted low-temperature-side shift temperature range (40 ° C.) (step S150). For this reason, the catalyst that each cell has in order to cause the reaction of the reaction gas by the fuel cell 100 is exposed to the high potential voltage Hv1 only in a low temperature environment (40 to 60 ° C.) shifted to the low temperature side. There is only there. Therefore, according to the fuel cell system 10 of the present embodiment, it is possible to suppress catalyst deterioration. In addition, in a situation where the SOC of the secondary battery 200 is on the fully charged side, it is less necessary to charge the secondary battery 200, and the fuel cell 100 has a high voltage Hv1 (the shifted high voltage). Since the operation is controlled so as not to exceed (potential avoidance voltage), the operation control range is widened. Therefore, since it becomes possible to drive the fuel cell 100 so as not to generate surplus power or to deal with battery charging with low necessity, it is possible to cope with charging of the secondary battery 200. .

  On the other hand, when the SOC of the secondary battery 200 is not the full charge side where it is 60% or less of the full charge, the secondary battery 200 needs to be replenished. In the fuel cell system 10 of the present embodiment, under such circumstances, the target temperature of the FC temperature is set to the normal FC temperature range (60 to 80 ° C.), so that the low temperature side shift temperature range (40 to 60 ° C.) of the target temperature is set. ) Is not performed. Moreover, in this case, the high potential avoidance voltage is obtained by setting the voltage Hv2 corresponding to the target temperature range (normal FC temperature range: 60 to 80 ° C.) during normal operation control of the fuel cell 100 as the high potential avoidance voltage. This is not performed for the shift to the high potential side. Therefore, since the catalyst of the fuel cell 100 is not exposed to a high potential in an environment of the normal FC temperature range (60 to 80 ° C.) that has not shifted to the low temperature side, according to the fuel cell system 10 of the present embodiment, It is possible to suppress catalyst deterioration. In addition, since the high potential avoidance voltage is not shifted to the high voltage side, the operation control width of the fuel cell 100 is narrowed, and the opportunity to perform surplus power generation is increased. Can be used for replenishment charging of the secondary battery 200, and charging of the secondary battery 200 can be dealt with.

  Moreover, in the fuel cell system 10 of the present embodiment, the correlation between the morphological change maintenance rate representing the state of catalyst catalytic function maintenance and the output voltage of the fuel cell 100 is correlated with the temperature in the normal FC temperature range (60 to 80 ° C.). And stored in the storage unit 710 in correspondence with the temperature in the low temperature side shift temperature range (40 to 60 ° C.) (see FIG. 3). Then, referring to the correlation corresponding to the temperature in these temperature ranges (target temperature range) (step S140), the high potential avoidance voltage is combined with the low temperature side shift (step S130) of the target temperature on the high voltage side. Shifted to. Therefore, according to the fuel cell system 10 of the present embodiment, the high potential avoidance voltage can be shifted to the high voltage side more reliably while maintaining the catalytic function using the form change maintenance rate. Thus, in determining the shift voltage on the high voltage side in consideration of the form change maintenance rate, the form change maintenance rate of 50% was set as the lower limit. Therefore, the catalyst of the fuel cell 100 can be made to function with a form change maintenance rate of 50%.

  Further, in the fuel cell system 10 of the present embodiment, when the FC temperature of the fuel cell 100 is lower than the temperature in the low temperature side shift temperature range (40 to 60 ° C.) that is the target temperature range (Yes determination in step S110). As described above, the SOC of the secondary battery 200 may decrease. At such a low FC temperature, if the high potential avoidance voltage is kept on the constant voltage side in the normal FC temperature range, as described above, the operation control width of the fuel cell 100 becomes narrow and excessive power generation is performed. Opportunities increase, and the secondary battery 200 is fully charged in an early stage, increasing the chances of surplus power generated by the fuel cell 100, resulting in power generation loss. On the other hand, in the fuel cell system 10 of the present embodiment, when the FC temperature is low as described above, regardless of the SOC of the fuel cell 100, that is, step S120 for determining the SOC is skipped, and the target temperature range is lowered. Even in the high potential avoidance voltage while shifting to the side shift temperature range (40 to 60 ° C.), the voltage shifts to the high voltage side voltage Hv1 corresponding to this low temperature side shift temperature range (40 to 60 ° C.). For this reason, the high voltage side shift of the high potential avoidance voltage makes it difficult for surplus power to be generated, and the charging of the secondary battery 200 becomes slow, and the power surplus can be suppressed. In addition, since the temperature of the fuel cell 100 is also maintained at a low temperature in the low temperature side shift temperature range (40 to 60 ° C.), which is the target temperature range, catalyst deterioration can be suppressed.

  As mentioned above, although the Example of this invention was described, this invention is not restricted to above-described embodiment, In the range which does not deviate from the summary, it is possible to implement in various aspects. For example, in the above-described embodiment, when the shift voltage on the high voltage side is determined in consideration of the form change maintenance rate, the form change maintenance rate of 50% is set as the lower limit. However, the following may be adopted. That is, as shown in FIG. 3, in the correlation between the change rate of the form change and the voltage for each temperature, the high change rate of the form change corresponding to the inflection point that causes the inflection in which the change form change rate suddenly changes to the reduction side. adopt. Along with the low temperature side shift of the target temperature range, the high potential avoidance voltage is shifted to the high voltage side voltage Hv3 at the inflection point corresponding to the low temperature side shift temperature range (40 to 60 ° C.). You can also By doing so, a high form change maintenance rate can be secured, so that the effectiveness of catalyst deterioration is further increased.

  Further, in maintaining the fuel cell 100 within the target temperature range, the refrigerant circulation method using the cooling system 500 is adopted in the above embodiment, but a gas cooling device is provided in the fuel gas supply system 300 or the oxidizing gas supply system 400. The temperature of the fuel cell 100 can be maintained by gas cooling and supplying the cooled gas.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell system 100 ... Fuel cell 110 ... Temperature sensor 200 ... Secondary battery 210 ... Capacity detection sensor 300 ... Fuel gas supply system 310 ... Fuel gas tank 320 ... Shut-off valve 330 ... Regulator 400 ... Oxidation gas supply system 410 ... Air cleaner 420 ... Air pump 421 ... Motor 430 ... Intercooler 435 ... Filter 440 ... Filter 500 ... Cooling system 510 ... Radiator 520 ... Circulation path 530 ... Circulation pump 610 ... Load 620 ... Cell monitor 700 ... Control unit 710 ... Storage unit

Claims (5)

A fuel cell system,
A fuel cell that generates power by receiving a supply of a reactive gas; and
Battery temperature detecting means for detecting the temperature of the fuel cell;
Battery temperature maintaining means for maintaining the temperature of the fuel cell so that the battery temperature detected by the battery temperature detecting means falls within a target temperature range;
Control means for controlling the operation of the fuel cell so that the output power of the fuel cell does not exceed a predetermined high potential avoidance voltage as an upper limit thereof;
A secondary battery that exchanges power with the fuel cell;
Charge detection means for detecting a charge capacity in the secondary battery;
If the charge capacity detected by the charge detection means is a full charge side, in addition to a voltage shift setting for shifting the high potential avoidance voltage to the high voltage side, a temperature shift setting for shifting the target temperature range to the low temperature side is set. A setting means for executing,
Fuel cell system. The fuel cell system according to claim 1,
The correlation between the change rate of the change in form and the output voltage of the fuel cell, which decreases when the output voltage of the fuel cell is high, which is the change rate of change in form of the fuel cell, which indicates the state of maintaining the catalytic function of the catalyst of the fuel cell, Characteristic storage means for storing each temperature of the fuel cell;
The fuel cell system, wherein the setting unit performs the voltage shift with reference to the correlation corresponding to the temperature in the target temperature range among the correlations stored in the characteristic storage unit.   The setting means executes the voltage shift setting so as to shift the high potential avoidance voltage to an output voltage on the high voltage side corresponding to the lower limit form change maintenance ratio of the form change maintenance ratio which is a lower limit in maintaining the catalyst function. The fuel cell system according to claim 2.   The setting means sets the output voltage on the high voltage side corresponding to the high form change maintenance rate that is a form change maintenance rate higher than the lower limit form change maintenance rate and causes inflection in the correlation of the form change maintenance rate. The fuel cell system according to claim 3, wherein the voltage shift setting is performed so as to shift a high potential avoidance voltage.   The setting means executes the temperature shift setting and the voltage shift setting regardless of the state of the charge capacity, when the detected battery temperature is a temperature deviating to a lower temperature side than the target temperature range. The fuel cell system according to any one of claims 1 to 4.

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