Fuel cell system

Abstract

The present invention provides a technology that can suppress the deterioration of the first air supply device and the second air supply device. [Solution] The fuel cell system comprises a fuel cell stack, a first air supply device, a second air supply device, and a control device. The first air supply device has the characteristic that it deteriorates more rapidly when supplied with air at a supply flow rate within a second range than when supplied with air at a supply flow rate within a first range. The second air supply device has the characteristic that it deteriorates more rapidly when supplied with air at a supply flow rate within a fourth range than when supplied with air at a supply flow rate within a third range. The control device is configured to perform the following: a process of determining the first supply flow rate and the second supply flow rate based on the requested flow rate, a first range, a second range, a third range, and a fourth range; and a process of controlling the operation of the first air supply device and the second air supply device.

Description

Technical Field

[0001] The technology disclosed in the present specification relates to a fuel cell system.

Background Art

[0002] Patent Document 1 discloses a fuel cell system including a fuel cell stack, an air supply device configured to supply air to the fuel cell stack, and a control device that controls operation of the air supply device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] In the fuel cell system of Patent Document 1, air is supplied to one fuel cell stack using one air supply device. In contrast to such a configuration, a configuration is conceivable in which two or more air supply devices are used to supply air to one fuel cell stack. In this case, it is desired to suppress deterioration of the two or more air supply devices.

[0005] The present specification provides a technology that can suppress deterioration of the first air supply device and the second air supply device.

Means for Solving the Problems

[0006] In a first aspect of this technology, the fuel cell system may include a fuel cell stack, a first air supply device configured to supply air to the fuel cell stack, a second air supply device configured to supply air to the fuel cell stack, and a control device for controlling the operation of the first air supply device and the second air supply device. The first air supply device may have the characteristic that the rate of deterioration progresses more rapidly when the air is supplied at a supply flow rate within a second range than when the air is supplied at a supply flow rate within a first range. The second air supply device may have the characteristic that the rate of deterioration progresses more rapidly when the air is supplied at a supply flow rate within a fourth range than when the air is supplied at a supply flow rate within a third range. The control device may be configured to perform the following: a process of acquiring the required flow rate of air requested by the fuel cell stack; a process of determining a first supply flow rate of air to be supplied by the first air supply device to the fuel cell stack and a second supply flow rate of air to be supplied by the second air supply device to the fuel cell stack, based on the required flow rate, the first range, the second range, the third range, and the fourth range; and a process of controlling the operation of the first air supply device and the second air supply device based on the first supply flow rate and the second supply flow rate.

[0007] In the above configuration, the frequency with which the first supply flow rate falls within the first range and the second supply flow rate falls within the third range can be improved. Therefore, deterioration of the first air supply device and the second air supply device can be suppressed.

[0008] In a second embodiment, in the first embodiment, the rated flow rate of the second air supply device may be greater than the rated flow rate of the first air supply device. The first range may be a range less than the first threshold flow rate, and the second range may be a range greater than or equal to the first threshold flow rate. The third range may be a range greater than or equal to the second threshold flow rate which is smaller than the first threshold flow rate, and the fourth range may be a range less than or equal to the second threshold flow rate. When the requested flow rate is less than the second threshold flow rate, the control device may, in the determination process, determine the first supply flow rate to a value equal to the requested flow rate and determine the second supply flow rate to zero.

[0009] According to the above configuration, the second air supply device is not driven when the required flow rate is below the second threshold flow rate. In other words, the second air supply device does not supply air at a flow rate within the fourth range. Therefore, deterioration of the second air supply device can be suppressed.

[0010] In a third embodiment, in the first or second embodiment described above, the rated flow rate of the second air supply device may be greater than the rated flow rate of the first air supply device. The first range may be a range less than the first threshold flow rate, and the second range may be a range greater than or equal to the first threshold flow rate. The third range may be a range greater than or equal to a second threshold flow rate that is smaller than the first threshold flow rate, and the fourth range may be a range less than or equal to the second threshold flow rate. When the requested flow rate is greater than or equal to the first threshold flow rate, the control device may, in the determination process, determine the second supply flow rate to be equal to the requested flow rate and determine the first supply flow rate to zero.

[0011] According to the above configuration, the first air supply device is not driven when the required flow rate is equal to or greater than the first threshold flow rate. In other words, the first air supply device does not supply air at a supply flow rate within the second range. Therefore, deterioration of the first air supply device can be suppressed.

[0012] In a fourth embodiment, in the first embodiment, the rated flow rate of the second air supply device may be the same as the rated flow rate of the first air supply device. The second range may be greater than or equal to the fifth threshold flow rate and less than the sixth threshold flow rate which is greater than the fifth threshold flow rate. The first range may be less than the fifth threshold flow rate and greater than or equal to the sixth threshold flow rate. The third range may be the same as the first range. The fourth range may be the same as the second range. The control device may, in the determination process, determine the first supply flow rate and the second supply flow rate to the equal distribution flow rate when the equal distribution flow rate, which is half the flow rate of the requested flow rate, is less than the fifth threshold flow rate, or when the equal distribution flow rate is greater than or equal to the sixth threshold flow rate.

[0013] According to the above configuration, when the equal distribution flow rate is less than the fifth threshold flow rate, or when the equal distribution flow rate is equal to or greater than the sixth threshold flow rate, the first air supply device and the second air supply device each supply air at a supply flow rate within the first and third ranges, respectively. Therefore, deterioration of the first air supply device and the second air supply device can be suppressed.

[0014] In a fifth embodiment, in the fourth embodiment, the fuel cell system may further include a memory for storing a first degradation index correlated with a first degree of degradation of the first air supply device and a second degradation index correlated with a second degree of degradation of the second air supply device. The control device may, in the determination process, determine the first supply flow rate to a value equal to the requested flow rate and the second supply flow rate to zero when the equal distribution flow rate is greater than or equal to the fifth threshold flow rate, the equal distribution flow rate is less than the sixth threshold flow rate, and the second degree of degradation is greater than the first degree of degradation. The control device may, in the determination process, determine the second supply flow rate to a value equal to the requested flow rate and the first supply flow rate to zero when the equal distribution flow rate is greater than or equal to the fifth threshold flow rate, the equal distribution flow rate is less than the sixth threshold flow rate, and the first degree of degradation is greater than the second degree of degradation.

[0015] According to the above configuration, the first degree of deterioration and the second degree of deterioration can be equalized. [Brief explanation of the drawing]

[0016] [Figure 1] This figure schematically shows the configuration of the fuel cell system 2 according to the first embodiment. [Figure 2] This figure shows examples of the first characteristic information 62 and the second characteristic information 64 relating to the first embodiment. [Figure 3] This is a flowchart of the air supply process performed by the control device 50 of the first embodiment. [Figure 4] This figure schematically shows the configuration of the fuel cell system 202 according to the second embodiment. [Figure 5] This figure shows an example of the first characteristic information 262 and the second characteristic information 264 relating to the second embodiment. [Figure 6] This is a flowchart of the air supply process performed by the control device 50 of the second embodiment. [Figure 7]This is a diagram schematically showing the configuration of a fuel cell system 302 according to the third modified example. Forms for Implementing the Invention

[0017] (First Embodiment) As shown in Figure 1, the fuel cell system 2 includes a fuel cell stack 10, a first air compressor 12, a second air compressor 14, a supply pipe 16, and a control device 50. As an example, the fuel cell system 2 is mounted on a fuel cell vehicle. The first air compressor 12 and the second air compressor 14 supply air containing oxygen to the fuel cell stack 10. The fuel cell stack 10 generates electric power by reacting oxygen contained in the air supplied from the first air compressor 12 and the second air compressor 14 with hydrogen supplied from a fuel tank (not shown). Note that in the present embodiment, the characteristics of the first air compressor 12 and the characteristics of the second air compressor 14 are different.

[0018] The supply pipe 16 supplies air containing oxygen to the fuel cell stack 10. The supply pipe 16 includes a first supply pipe 20, a second supply pipe 22, and a third supply pipe 24. The first supply pipe 20 and the second supply pipe 22 are connected to the third supply pipe 24 in parallel with each other. The upstream end of the first supply pipe 20 is open to the outside of the fuel cell system 2. In the first supply pipe 20, the first air compressor 12, the first check valve 30, the first valve 32, and the first flow rate sensor 34 are arranged in order from the upstream side. The first valve 32 opens and closes the flow path in the first supply pipe 20.

[0019] The upstream end of the second supply pipe 22 is open to the outside of the fuel cell system 2. In the second supply pipe 22, the second air compressor 14, the second check valve 40, the second valve 42, and the second flow rate sensor 44 are arranged in order from the upstream side. The second valve 42 opens and closes the flow path in the second supply pipe 22.

[0020] The upstream end of the third supply pipe 24 is connected to the first supply pipe 20 and the second supply pipe 22. The downstream end of the third supply pipe 24 is connected to the fuel cell stack 10.

[0021] The control device 50 includes a CPU 52 and a memory 54. The CPU 52 executes various processes in accordance with a program 60 stored in the memory 54. The memory 54 is configured by a volatile memory, a non-volatile memory, or the like. The memory 54 further stores first characteristic information 62 and second characteristic information 64. The first characteristic information 62 and the second characteristic information 64 are information indicating the characteristics of the first air compressor 12 and the characteristics of the second air compressor 14, respectively.

[0022] The first characteristic information 62 and the second characteristic information 64 will be described with reference to Figure 2. The first characteristic information 62 and the second characteristic information 64 are information indicating the correlation between the supply flow rate of the air compressor and the progress degree of deterioration of the air compressor. The first characteristic information 62 is divided into a first air flow rate range R1 and a second air flow rate range R2. The first air compressor 12 has a characteristic that the progress degree of deterioration is higher when supplying air at a supply flow rate within the second air flow rate range R2 than when supplying air at a supply flow rate within the first air flow rate range R1. That is, the first air flow rate range R1 and the second air flow rate range R2 can be referred to as a deterioration suppression range and a deterioration acceleration range, respectively. In Figure 2 and Figure 5 described later, hatching is applied to the deterioration acceleration range. The first air flow rate range R1 is a range from a first flow rate F1 to a second flow rate F2. The first flow rate F1 is the same as the minimum flow rate of air that the first air compressor 12 can supply. The second air flow rate range R2 is a range from the second flow rate F2 to a third flow rate F3. The third flow rate F3 is the same as the rated flow rate RF1 of the first air compressor 12.

[0023] The second characteristic information 64 is divided into a third air volume range R3 and a fourth air volume range R4. The third air volume range R3 and the fourth air volume range R4 are the degradation suppression range and the degradation acceleration range, respectively. The third air volume range R3 is the range from the fourth flow rate F4 to the fifth flow rate F5. The fourth flow rate F4 is smaller than the second flow rate F2. The fifth flow rate F5 is larger than the third flow rate F3. The fifth flow rate F5 is the same as the rated flow rate RF2 of the second air compressor 14. That is, the rated flow rate RF2 of the second air compressor 14 is larger than the rated flow rate RF1 of the first air compressor 12. The fourth air volume range R4 is the range from the first flow rate F1 to the fourth flow rate F4. The first flow rate F1 is the same as the minimum air flow rate that the second air compressor 14 can supply.

[0024] As described above, the first air compressor 12 and the second air compressor 14 differ in their rated flow rate, degradation acceleration range, and degradation suppression range. Specifically, the second air compressor 14, which has a higher rated flow rate, has a degradation acceleration range on the low flow rate side. On the other hand, the first air compressor 12, which has a lower rated flow rate, has a degradation acceleration range on the high flow rate side.

[0025] (Air supply treatment; Figure 3) Referring to Figure 3, the air supply process performed by the control device 50 of the fuel cell system 2 will be described. At the start of the air supply process, the first valve 32 and the second valve 42 are open. The control device 50 performs the process shown in Figure 3 at predetermined intervals.

[0026] In S10, the control device 50 obtains the required air flow rate RF required by the fuel cell stack 10. The required flow rate is determined according to the required output corresponding to the required power of the traction motor (not shown).

[0027] In S12, the control device 50 determines whether the requested flow rate RF obtained in S10 is less than the fourth flow rate F4. That is, the control device 50 determines whether the requested flow rate RF is within the fourth air volume range R4. If the requested flow rate RF is less than the fourth flow rate F4 (YES in S12), the control device 50 proceeds to S14. On the other hand, if the requested flow rate RF is not less than the fourth flow rate F4 (NO in S12), the control device 50 proceeds to S20.

[0028] In S14, the control device 50 determines the first supply flow rate SF1 of air that the first air compressor 12 should supply to the fuel cell stack 10, and the second supply flow rate SF2 of air that the second air compressor 14 should supply to the fuel cell stack 10. Specifically, the control device 50 determines the first supply flow rate SF1 to be equal to the required flow rate RF, and determines the second supply flow rate SF2 to be zero.

[0029] In S16, the control device 50 controls the operation of the first air compressor 12 and the second air compressor 14 based on the first supply flow rate SF1 and the second supply flow rate SF2. Specifically, in S16 after S14, the control device 50 operates the first air compressor 12 so that air at the required flow rate RF is supplied to the fuel cell stack 10, while not driving the second air compressor 14. As a result, the second air compressor 14 does not supply air at a supply flow rate within the fourth air volume range R4. When S16 ends, the control device 50 terminates the process shown in Figure 3.

[0030] Furthermore, in S20, the control device 50 determines whether the requested flow rate RF is less than the second flow rate F2. That is, the control device 50 determines whether the requested flow rate RF is outside the second air volume range R2. If the requested flow rate RF is less than the second flow rate F2 (YES in S20), the control device 50 proceeds to S22. On the other hand, if the requested flow rate RF is not less than the second flow rate F2 (NO in S20), the control device 50 proceeds to S30.

[0031] In S22, the control device 50 uses the requested flow rate RF to determine the first supply flow rate SF1 and the second supply flow rate SF2. The control device 50 distributes the requested flow rate RF to the first supply flow rate SF1 and the second supply flow rate SF2 such that the first supply flow rate SF1 falls within the first air volume range R1 and the second supply flow rate SF2 falls within the third air volume range R3. When S22 is completed, the control device 50 proceeds to S16.

[0032] In S16, following S30, the control device 50 controls the operation of the first air compressor 12 so that air at a first supply flow rate SF1 is supplied to the fuel cell stack 10, and controls the operation of the second air compressor 14 so that air at a second supply flow rate SF2 is supplied to the fuel cell stack 10.

[0033] In S30, the control device 50 sets the first supply flow rate SF1 to zero and the second supply flow rate SF2 to a value equal to the requested flow rate RF. When S30 is finished, the control device 50 proceeds to S16.

[0034] In S16, after S30, the control device 50 operates the second air compressor 14 to supply air at the required flow rate RF to the fuel cell stack 10, while not driving the first air compressor 12. As a result, the first air compressor 12 does not supply air at a supply flow rate within the second air volume range R2.

[0035] As described above, the fuel cell system 2 comprises a fuel cell stack 10, a first air compressor 12 (an example of a "first air supply device"), a second air compressor 14 (an example of a "second air supply device"), and a control device 50. The first air compressor 12 has the characteristic that it deteriorates more rapidly when supplied with air at a supply flow rate within the second air volume range R2 (an example of a "second range") than when supplied with air at a supply flow rate within the first air volume range R1 (an example of a "first range"). The second air compressor 14 has the characteristic that it deteriorates more rapidly when supplied with air at a supply flow rate within the fourth air volume range R4 (an example of a "fourth range") than when supplied with air at a supply flow rate within the third air volume range R3 (an example of a "third range"). The control device 50 is configured to perform the following processes: acquiring the required air flow rate RF requested by the fuel cell stack 10 (S10 in Figure 2); determining the first supply flow rate SF1 and the second supply flow rate SF2 based on the required flow rate RF, the first air volume range R1, the second air volume range R2, the third air volume range R3, and the fourth air volume range R4 (S12, 14, S20, S22, S30); and controlling the operation of the first air compressor 12 and the second air compressor 14 (S16).

[0036] In the above configuration, the frequency with which the first supply flow rate SF1 falls within the first air volume range R1 and the second supply flow rate SF2 falls within the third air volume range R3 can be improved. Therefore, deterioration of the first air compressor 12 and the second air compressor 14 can be suppressed.

[0037] Furthermore, the rated flow rate RF2 of the second air compressor 14 is greater than the rated flow rate RF1 of the first air compressor 12. The first air volume range R1 is a range less than the second flow rate F2 (an example of the "first threshold flow rate"), and the second air volume range R2 is a range greater than or equal to the second flow rate F2. The third air volume range R3 is a range greater than or equal to the fourth flow rate F4 (an example of the "second threshold flow rate"), and the fourth air volume range R4 is a range less than the fourth flow rate F4. When the requested flow rate RF is less than the fourth flow rate F4 (YES in S12), the control device 50 determines the first supply flow rate SF1 to be equal to the requested flow rate RF and determines the second supply flow rate SF2 to zero (S14).

[0038] According to the above configuration, the second air compressor 14 is not driven when the required flow rate RF is less than the fourth flow rate F4. In other words, the second air compressor 14 does not supply air at a supply flow rate within the fourth air volume range R4. Therefore, deterioration of the second air compressor 14 can be suppressed.

[0039] Furthermore, when the requested flow rate RF is greater than or equal to the second flow rate F2 (NO in S20), the control device 50 determines the second supply flow rate SF2 to be equal to the requested flow rate RF, and determines the first supply flow rate SF1 to be zero (S30).

[0040] According to the above configuration, the first air compressor 12 is not driven when the required flow rate RF is equal to or greater than the second flow rate F2. In other words, the first air compressor 12 does not supply air at a supply flow rate within the second air volume range R2. Therefore, deterioration of the first air compressor 12 can be suppressed.

[0041] (Second example) Referring to Figure 4, the fuel cell system 202 of the second embodiment will be described. Components common to both embodiments are denoted by the same reference numerals, and their descriptions are omitted.

[0042] The fuel cell system 202 of the second embodiment includes a first air compressor 212 and a second air compressor 214. The first air compressor 212 and the second air compressor 214 have different characteristics from the first air compressor 12 and the second air compressor 14 of the first embodiment. Also, the first air compressor 212 and the second air compressor 214 have the same characteristics.

[0043] The memory 54 of the control device 50 in the second embodiment stores first characteristic information 262, second characteristic information 264, first degradation index 266, and second degradation index 268. The first characteristic information 262 and the second characteristic information 264 are information indicating the characteristics of the first air compressor 212 and the characteristics of the second air compressor 214, respectively.

[0044] As shown in Figure 5, the first characteristic information 262 is divided into a first air volume range R11 and a second air volume range R12. The first air volume range R11 and the second air volume range R12 are the degradation suppression range and the degradation acceleration range, respectively. The first air volume range R11 is the range from the first flow rate F11 to the second flow rate F12, and the range from the third flow rate F13 to the fourth flow rate F14. The first flow rate F11 is the same as the minimum air flow rate that the first air compressor 212 and the second air compressor 214 can supply. The third flow rate F13 is greater than the second flow rate F12. The fourth flow rate F14 is the same as the rated flow rate RF11 of the first air compressor 212 and the rated flow rate RF12 of the second air compressor 214. The second air volume range R12 is the range from the second flow rate F12 to the third flow rate F13. The second characteristic information 264 is divided into the third air volume range R13 and the fourth air volume range R14. The third air volume range R13 and the fourth air volume range R14 are the same as the first air volume range R11 and the second air volume range R12, respectively. That is, the first characteristic information 262 and the second characteristic information 264 are the same. Thus, the rated flow rate, degradation suppression range, and degradation acceleration range are the same for the first air compressor 212 and the second air compressor 214.

[0045] The first degradation index 266 and the second degradation index 268 are information indicating the degree of degradation of the first air compressor 212 and the second air compressor 214, respectively. For example, the degradation index may include information such as the time spent operating in a predetermined rotational speed range and the heat load received by the air compressor.

[0046] (Air supply treatment; Figure 6) Referring to Figure 6, the air supply process performed by the control device 50 of the fuel cell system 202 will be described.

[0047] S110 is the same as S10 in Figure 3.

[0048] In S112, the control device 50 determines whether the equal distribution flow rate exceeds the second flow rate F12 and is less than the third flow rate F13. The equal distribution flow rate is half the required flow rate RF. Specifically, the control device 50 determines whether the equal distribution flow rate is within the second air volume range R12. If the equal distribution flow rate is within the second air volume range R12 (YES in S112), the control device 50 proceeds to S114. On the other hand, if the equal distribution flow rate is not within the second air volume range R12 (NO in S112), the control device 50 proceeds to S130. Note that NO in S112 means that the equal distribution flow rate is within the second air volume range R12, i.e., within the degradation suppression region.

[0049] In S114, the control device 50 uses the first degradation index 266 and the second degradation index 268 in the memory 54 to determine whether the second degree of degradation is greater than the first degree of degradation. That is, the control device 50 determines whether the second air compressor 214 is more degraded than the first air compressor 212. If the second degree of degradation is greater than the first degree of degradation (YES in S114), the control device 50 proceeds to S116. On the other hand, if the second degree of degradation is not greater than the first degree of degradation (YES in S114), the control device 50 proceeds to S120.

[0050] In S116, the control device 50 determines the first supply flow rate SF11 to be equal to the requested flow rate RF, and determines the second supply flow rate SF12 to be zero.

[0051] In S118, the control device 50 controls the operation of the first air compressor 212 and the second air compressor 214 based on the first supply flow rate SF11 and the second supply flow rate SF12. In S118, following S116, the control device 50 operates the first air compressor 212 so that air at the required flow rate RF is supplied to the fuel cell stack 10, while not driving the second air compressor 214. When S118 is completed, the control device 50 terminates the process shown in Figure 6.

[0052] Furthermore, in S120, the control device 50 determines the second supply flow rate SF12 to be equal to the requested flow rate RF, and also determines the first supply flow rate SF11 to be zero. When S120 is completed, the control device 50 proceeds to S118.

[0053] In S118, following S120, the control device 50 operates the second air compressor 214 so that air at the required flow rate RF is supplied to the fuel cell stack 10, while not driving the first air compressor 212.

[0054] Furthermore, in S130, the control device 50 determines the first supply flow rate SF11 and the second supply flow rate SF12 to be equal to the equal distribution flow rate (i.e., the requested flow rate RF / 2).

[0055] In S118, following S130, the control device 50 operates the first air compressor 212 and the second air compressor 214 respectively so that air at an equal distribution flow rate is supplied to the fuel cell stack 10.

[0056] As described above, the rated flow rate of the second air compressor 214 (an example of the "second air supply device") is the same as the rated flow rate of the first air compressor 212 (an example of the "first air supply device"). The second air volume range R12 (an example of the "second range") is the range in which the second flow rate F12 (an example of the "fifth threshold flow rate") is greater than or equal to and less than the third flow rate F13 (an example of the "sixth threshold flow rate"). The first air volume range R11 (an example of the "first range") is the range in which the second flow rate F12 is less than and greater than the third flow rate F13. The third air volume range R13 (an example of the "third range") is the same as the first air volume range R11. The fourth air volume range R14 (an example of the "fourth range") is the same as the second air volume range R12. The control device 50 determines the first supply flow rate SF11 and the second supply flow rate SF12 to be equal distribution flow rates (S130) when the equal distribution flow rate is less than the second flow rate F12 or the equal distribution flow rate is greater than or equal to the third flow rate F13 (NO in S112).

[0057] According to the above configuration, when the equal distribution flow rate is less than the fifth threshold flow rate, or when the equal distribution flow rate is equal to or greater than the sixth threshold flow rate, the first supply flow rate SF11 and the second supply flow rate SF12 are determined to be equal distribution flow rates. With this configuration, it is possible to suppress the deterioration of the first air compressor 212 and the second air compressor 214.

[0058] The fuel cell system 2 is further equipped with a memory 54 that stores a first degradation index 266 and a second degradation index 268. The control device 50 determines the first supply flow rate SF11 to be equal to the requested flow rate RF and the second supply flow rate SF12 to zero (S116) when the equal distribution flow rate is greater than or equal to the second flow rate F12, the equal distribution flow rate is less than the third flow rate F13, and the second degradation degree is greater than the first degradation degree (YES in S112, YES in S114). The control device 50 determines the second supply flow rate SF12 to be equal to the requested flow rate RF and the first supply flow rate SF11 to zero (S120) when the equal distribution flow rate is greater than or equal to the second flow rate F12, the equal distribution flow rate is less than the third flow rate F13, and the degree of deterioration of the first is greater than the degree of deterioration of the second (YES in S112, NO in S114).

[0059] According to the above configuration, the first degree of deterioration and the second degree of deterioration can be equalized.

[0060] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above.

[0061] (First variation) The "air supply device" is not limited to an air compressor, but may also be a blower or the like.

[0062] (Second Modification) In the first and second embodiments, three or more air compressors may be connected to the fuel cell stack 10.

[0063] (Third Modified Example) As shown in Figure 7, the fuel cell system 2 may include a supply pipe 316 having a first supply pipe 320 and a second supply pipe 322. In this modified example, the downstream end of the first supply pipe 320 and the downstream end of the second supply pipe 322 are connected to the fuel cell stack 10. The pipe connected to the first supply pipe 320 and the pipe connected to the second supply pipe 322 in the fuel cell stack 10 may be merged within the fuel cell stack 10 or may be independent within the fuel cell stack 10.

[0064] (Fourth modified example) In the first embodiment, S20 in Figure 3 can be omitted. In this modified example, the control device 50 may execute the process in S22 if it is determined to be NO in S12.

[0065] (Fifth Modification) In step S30 of Figure 3, the control device 50 may determine the first supply flow rate SF1 to be equal to the requested flow rate RF, and the second supply flow rate SF2 to be zero. In another modification, in step S30 of Figure 3, the control device 50 may determine the second supply flow rate SF2 to be equal to the requested flow rate RF, and the first supply flow rate SF1 to be zero.

[0066] (Sixth Modification) In the first embodiment, the control device 50 may execute S14 when the requested flow rate RF is less than the second flow rate, and execute S30 when the requested flow rate RF is equal to or greater than the second flow rate.

[0067] (Seventh Modification) In the second embodiment, S114 in Figure 6 can be omitted. In this modification, the control device 50 may alternately operate the first air compressor 212 and the second air compressor 214 when it is determined that S112 is YES.

[0068] Furthermore, the technical elements described herein or in the drawings demonstrate technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technologies illustrated herein or in the drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives itself constitutes technical usefulness. [Explanation of Symbols]

[0069] 2: Fuel cell system, 10: Fuel cell stack, 12: First air compressor, 14: Second air compressor, 16: Supply piping, 20: First supply piping, 22: Second supply piping, 24: Third supply piping, 30: First check valve, 32: First valve, 34: First flow sensor, 40: Second check valve, 42: Second valve, 44: Second flow sensor, 50: Control device, 52: CPU, 54: Memory, 60: Program, 62: First characteristic information, 64: Second characteristic information, 202: Fuel cell system, 212: First air compressor, 214: Second air compressor, 262: First characteristic information, 264: Second characteristic information, 266: First degradation index, 268: Second degradation index, 316: Supply piping, 320: First supply piping, 322: Second supply piping

Claims

1. A fuel cell system, Fuel cell stack and A first air supply device configured to supply air to the fuel cell stack, A second air supply device configured to supply the air to the fuel cell stack, A control device that controls the operation of the first air supply device and the second air supply device, Equipped with, The first air supply device has the characteristic that the rate of deterioration progresses more rapidly when the air is supplied at a supply flow rate within a second range than when the air is supplied at a supply flow rate within a first range. The second air supply device has the characteristic that the rate of deterioration progresses more rapidly when the air is supplied at a supply flow rate within a fourth range than when the air is supplied at a supply flow rate within a third range. The control device is A process for obtaining the required flow rate of air requested by the fuel cell stack, A process for determining, based on the requested flow rate, the first range, the second range, the third range, and the fourth range, a first supply flow rate of air to be supplied to the fuel cell stack by the first air supply device, and a second supply flow rate of air to be supplied to the fuel cell stack by the second air supply device. The system is configured to perform a process that controls the operation of the first air supply device and the second air supply device based on the first supply flow rate and the second supply flow rate. Fuel cell system.

2. The rated flow rate of the second air supply device is greater than the rated flow rate of the first air supply device. The first range is the range below the first threshold flow rate, and the second range is the range above the first threshold flow rate. The third range is a range greater than or equal to a second threshold flow rate that is smaller than the first threshold flow rate, and the fourth range is a range less than or equal to the second threshold flow rate. The fuel cell system according to claim 1, wherein, when the requested flow rate is less than the second threshold flow rate, the control device determines the first supply flow rate to be equal to the requested flow rate and the second supply flow rate to be zero in the determination process.

3. The rated flow rate of the second air supply device is greater than the rated flow rate of the first air supply device. The first range is the range below the first threshold flow rate, and the second range is the range above the first threshold flow rate. The third range is a range greater than or equal to a second threshold flow rate that is smaller than the first threshold flow rate, and the fourth range is a range less than or equal to the second threshold flow rate. The fuel cell system according to claim 1, wherein the control device, when the requested flow rate is equal to or greater than the first threshold flow rate, determines the second supply flow rate to a value equal to the requested flow rate and determines the first supply flow rate to zero in the determination process.

4. The rated flow rate of the second air supply device is the same as the rated flow rate of the first air supply device. The second range is the range that is greater than or equal to the fifth threshold flow rate and less than the sixth threshold flow rate which is greater than the fifth threshold flow rate, and the first range is the range that is less than the fifth threshold flow rate and greater than or equal to the sixth threshold flow rate. The third range is the same as the first range, The fourth range is the same as the second range, The fuel cell system according to claim 1, wherein the control device determines the first supply flow rate and the second supply flow rate to be the equal distribution flow rate when the equal distribution flow rate, which is half the flow rate of the requested flow rate, is less than the fifth threshold flow rate, or when the equal distribution flow rate is equal to or greater than the sixth threshold flow rate, in the determination process.

5. The system further includes a memory for storing a first deterioration index correlated with a first degree of deterioration of the first air supply device, and a second deterioration index correlated with a second degree of deterioration of the second air supply device. The control device is When the equal distribution flow rate is greater than or equal to the fifth threshold flow rate, and the equal distribution flow rate is less than the sixth threshold flow rate, and the second degree of deterioration is greater than the first degree of deterioration, in the determination process, the first supply flow rate is determined to be equal to the requested flow rate, and the second supply flow rate is determined to be zero. When the equal distribution flow rate is greater than or equal to the fifth threshold flow rate, and the equal distribution flow rate is less than the sixth threshold flow rate, and the first degree of deterioration is greater than the second degree of deterioration, in the determination process, the second supply flow rate is determined to be equal to the requested flow rate, and the first supply flow rate is determined to be zero. The fuel cell system according to claim 4.

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