JP2012059449A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy in determining clogging of a filter.SOLUTION: A fuel cell system having a fuel cell, a compressor and a filter comprises: flow rate detection means (S1) for detecting the flow rate of cathode gas discharged from the compressor; pressure detection means (S1) for detecting the pressure of the cathode gas discharged from the compressor; rotational speed detection means (S1) for detecting the rotational speed of the compressor; threshold calculation means (S2) for calculating, based on detection values of two parameters among the flow rate, pressure and rotational speed, a filter clogging determination threshold of the remaining one of the parameters; and filter clogging determination means (S3) for determining whether or not the filter is clogged by comparing a detection value of the remaining one of the parameters with the filter clogging determination threshold.

Description

  The present invention relates to a fuel cell system.

The conventional fuel cell system includes a filter upstream of the cathode gas supply compressor, and determines whether the filter is clogged based on the actual power consumption of the compressor and the estimated power consumption of the compressor. (See Patent Document 1).
JP 2006-216478 A

  However, in order to measure the power consumption, it is necessary to measure and multiply the voltage and current. The measured voltage and current each have an error, and the error is further increased by multiplying them. Therefore, there is a problem that the detection accuracy of the power consumption is low, and as a result, the determination accuracy of filter clogging is also low.

  The present invention has been made paying attention to such conventional problems, and an object thereof is to improve the accuracy of filter clogging determination.

  The present invention relates to a fuel cell that generates power by receiving supply of anode gas and cathode gas, a compressor that supplies cathode gas to the fuel cell, and a foreign substance in the cathode gas that is provided upstream of the compressor and is supplied to the fuel cell. And a filter. And a flow rate detecting means for detecting the flow rate of the cathode gas discharged from the compressor, a pressure detecting means for detecting the pressure of the cathode gas discharged from the compressor, a rotational speed detecting means for detecting the rotational speed of the compressor, and a flow rate. , A threshold value calculation means for calculating a filter clogging determination threshold value for the remaining parameters based on detection values of two parameters of the pressure and the rotation speed, a detection value of the remaining parameters, a filter clogging determination threshold value, And filter clogging determining means for determining whether or not the filter is clogged.

  According to the present invention, if two of the three parameters of flow rate, pressure, and rotation speed are fixed, the remaining parameters change regularly according to the degree of filter clogging. In addition to determining filter clogging, a rotational speed with high detection accuracy was used for one of the three parameters. Therefore, the filter clogging determination accuracy can be improved as compared with the comparison based on electric power.

1 is a schematic view of a fuel cell system 100 according to a first embodiment. FIG. 6 is a diagram showing a relationship between a filter foreign matter accumulation amount α and a compressor rotation speed R. It is the figure which showed the relationship between the filter foreign material accumulation amount (alpha) and the compressor outlet pressure P. FIG. It is the figure which showed the relationship between filter foreign material accumulation amount (alpha) and cathode gas flow volume Q. FIG. It is a flowchart explaining filter clogging determination control by 1st Embodiment. It is the figure which showed the compressor operation area | region. It is a flowchart explaining the filter clogging determination control by 2nd Embodiment. It is a flowchart explaining filter clogging determination control by 3rd Embodiment. FIG. 6 is a diagram showing a relationship between a filter foreign matter accumulation amount α and a compressor rotation speed R. It is a flowchart explaining the filter clogging determination control by 4th Embodiment. It is the figure which showed the relationship between filter foreign material accumulation amount (alpha) and filter pressure loss (DELTA) P. It is a flowchart explaining the filter clogging determination control by 5th Embodiment. It is a figure explaining a quasi-steady state. It is a flowchart explaining filter clogging determination control by 6th Embodiment. It is a flowchart explaining the filter clogging determination control by 7th Embodiment. It is the figure which showed the relationship between compressor rotational speed Rlim and atmospheric pressure Patm. It is the figure which showed the relationship between compressor rotational speed Rlim and intake air temperature Tin. It is a flowchart explaining the filter clogging determination control by 8th Embodiment. It is the figure which showed the relationship between compressor outlet pressure Plim and atmospheric pressure Patm. It is a flowchart explaining the filter clogging determination control by 9th Embodiment. It is the figure which showed the relationship between cathode gas flow volume Qlim and atmospheric pressure Patm. It is the figure which showed the relationship between cathode gas flow volume Qlim and intake air temperature Tin. It is a flowchart explaining the filter clogging determination control by 10th Embodiment. It is a flowchart explaining filter clogging determination control by 11th Embodiment. It is a flowchart explaining filter clogging determination control by 12th Embodiment.

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

(First embodiment)
In a fuel cell, an electrolyte membrane is sandwiched between an anode electrode (fuel electrode) and a cathode electrode (oxidant electrode), an anode gas containing hydrogen in the anode electrode (fuel gas), and a cathode gas containing oxygen in the cathode electrode (oxidant) Electricity is generated by supplying gas. The electrode reaction that proceeds in both the anode electrode and the cathode electrode is as follows.

Anode electrode: 2H ₂ → 4H ⁺ + 4e ⁻ (1)
Cathode electrode: 4H ⁺ + 4e ⁻ + O ₂ → 2H ₂ O (2)

  The fuel cell generates an electromotive force of about 1 volt by the electrode reactions (1) and (2).

  When such a fuel cell is used as a power source for automobiles, a large amount of electric power is required, so that it is used as a fuel cell stack in which several hundred fuel cells are stacked. Then, a fuel cell system that supplies anode gas and cathode gas to the fuel cell stack is configured, and electric power for driving the vehicle is taken out.

  FIG. 1 is a schematic diagram of a fuel cell system 100 according to a first embodiment of the present invention.

  The fuel cell system 100 includes a fuel cell stack 1, a cathode gas supply device 2, and a controller 3. Since the apparatus for supplying the anode gas to the fuel cell stack 1 is not the main part of the present invention, the illustration is omitted to facilitate understanding of the invention.

  The fuel cell stack 1 is formed by stacking a plurality of fuel cells, and generates power upon receiving supply of anode gas and cathode gas.

  The cathode gas supply device 2 includes a cathode gas supply passage 20 through which cathode gas supplied to the fuel cell stack 1 flows, and a cathode gas discharge passage 21 through which cathode off-gas discharged from the fuel cell stack 1 flows. In this embodiment, air in the atmosphere is taken in and used as the cathode gas.

  In the cathode gas supply passage 20, an atmospheric pressure gauge 22, a thermometer 23, a filter 24, a flow meter 25, a compressor 26, and a pressure gauge 27 are provided in order from the upstream.

  The barometer 22 detects the pressure of the outside air.

  The thermometer 23 detects the temperature of the cathode gas supplied to the fuel cell stack 1 (hereinafter referred to as “intake air temperature”).

  The filter 24 removes foreign matters such as dust and dirt from the cathode gas flowing through the cathode gas supply passage 20.

  The flow meter 25 detects the flow rate of the cathode gas flowing through the cathode gas supply passage 20. In the present embodiment, a mass flow meter is used as the flow meter 25, but a volume flow meter may be used.

  The compressor 26 is a centrifugal compressor and is driven by the motor 4 to adjust the flow rate of the cathode gas supplied to the fuel cell stack 1. The rotation speed of the compressor 26 is controlled by the controller 3 controlling the rotation speed of the motor 4 via the inverter 5. The compressor 26 is provided with a rotation speed meter 28 that detects the rotation speed of the compressor 26.

  The pressure gauge 27 detects the pressure of the cathode gas discharged from the compressor 26, that is, the compressor outlet pressure.

  A pressure regulating valve 29 is provided in the cathode gas discharge passage 21.

  The pressure adjustment valve 29 is an on-off valve whose opening degree can be freely adjusted. The opening degree is controlled by the controller 3 to adjust the pressure of the cathode gas supplied to the fuel cell stack 1.

  The controller 3 includes a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). The controller 3 receives signals from various sensors that detect the operating state of the fuel cell system 100 such as an accelerator stroke sensor 31 that detects the amount of depression of the accelerator pedal. The controller 3 calculates the target power generation amount of the fuel cell stack 1 based on these input signals, and the rotational speed of the compressor 26 and the pressure adjustment valve 29 so that the power generation amount of the fuel cell stack 1 becomes the target power generation amount. Control the opening.

  Incidentally, foreign substances removed from the cathode gas gradually accumulate on the filter 24. When the amount of foreign matter accumulated on the filter 24 (hereinafter referred to as “filter foreign matter accumulation amount”) α increases, the filter 24 becomes clogged and the pressure loss before and after the filter (hereinafter referred to as “filter pressure loss”) ΔP increases. . As a result, a desired cathode gas flow rate may not be obtained during high-load operation. Further, the compressor 26 may be rotated beyond the guaranteed rotational speed in order to obtain a desired cathode gas flow rate. Therefore, in order to ensure the reliability and safety of the fuel cell system 100, it is determined whether or not the filter 24 is clogged, that is, a predetermined accumulation amount (hereinafter referred to as “filter clogging amount”) in which the filter foreign matter accumulation amount α can be determined as filter clogging. It is necessary to accurately determine whether or not it exceeds αlim.

  Therefore, in this embodiment, it is accurately determined whether or not the filter 24 is clogged by using the detection value of the tachometer 28 with high detection accuracy as one of the parameters used when determining filter clogging. Specifically, it is accurately determined whether or not the filter 24 is clogged using the three parameters of the cathode gas flow rate Q, the compressor outlet pressure P, and the compressor rotation speed R. Hereinafter, the relationship between these three parameters will be described with reference to FIGS.

  FIG. 2 is a graph showing the relationship between the filter foreign matter accumulation amount α and the compressor rotational speed R when the cathode gas flow rate Q and the compressor outlet pressure P are a predetermined value.

  As shown in FIG. 2, the compressor rotation speed R when the cathode gas flow rate Q and the compressor outlet pressure P are a predetermined value varies depending on the filter foreign matter accumulation amount α. Specifically, as the filter foreign matter accumulation amount α increases, the compressor rotation speed R for setting the cathode gas flow rate Q and the compressor outlet pressure P to a predetermined value increases.

  FIG. 3 is a diagram showing the relationship between the filter foreign matter accumulation amount α and the compressor outlet pressure P when the cathode gas flow rate Q and the compressor rotational speed R are at a predetermined value.

  As shown in FIG. 3, the compressor outlet pressure P when the cathode gas flow rate Q and the compressor rotation speed R are a predetermined value varies depending on the filter foreign matter accumulation amount α. Specifically, the larger the filter foreign matter accumulation amount α, the lower the compressor outlet pressure P when the cathode gas flow rate Q and the compressor rotational speed R are at a predetermined value.

  FIG. 4 is a diagram showing the relationship between the filter foreign matter accumulation amount α and the cathode gas flow rate Q when the compressor outlet pressure P and the compressor rotation speed R are predetermined values.

  As shown in FIG. 4, the cathode gas flow rate Q when the compressor outlet pressure P and the compressor rotation speed R are a predetermined value varies depending on the filter foreign matter accumulation amount α. Specifically, the larger the filter foreign matter accumulation amount α, the lower the cathode gas flow rate Q when the compressor outlet pressure P and the compressor rotation speed R are at a predetermined value.

  As described above, if two parameters are fixed among the three parameters of the cathode gas flow rate Q, the compressor outlet pressure P, and the compressor rotation speed R, the remaining one parameter is regularized according to the filter foreign matter accumulation amount α. To change.

  Therefore, if the filter clogging amount αlim is set in advance, the compressor rotation speed Rlim at the filter clogging amount αlim in the case where the cathode gas flow rate Q and the compressor outlet pressure P are a predetermined value is obtained from the relationship shown in FIG. I understand.

  Further, from the relationship shown in FIG. 3, the compressor outlet pressure PPlim at the time of the filter clogging amount αlim when the cathode gas flow rate Q and the compressor rotation speed R are a predetermined value can be known.

  Further, from the relationship shown in FIG. 4, the cathode gas flow rate Qlim at the filter clogging amount αlim in the case where the compressor outlet pressure P and the compressor rotation speed R are predetermined values is known.

  Therefore, in this embodiment, it is determined whether the filter 24 is clogged using the relationship shown in FIG. Specifically, the compressor rotation speed Rlim when the filter foreign matter accumulation amount α is the filter clogging amount αlim is determined according to each cathode gas flow rate Q and the compressor outlet pressure P from the relationship shown in FIG. And is stored in the controller 3. Based on the cathode gas flow rate Qmea and the compressor outlet pressure Pmea actually detected by the flow meter 25 and the pressure gauge 27, the compressor rotation speed Rlim (filter clogging determination threshold value) when the filter foreign matter accumulation amount α is the filter clogging amount αlim. Is calculated. Then, when the compressor rotational speed Rmea actually detected by the rotational speed meter 28 becomes higher than the calculated compressor rotational speed Rlim, it is determined that the filter 24 is clogged. Hereinafter, filter clogging determination control according to this embodiment will be described.

  FIG. 5 is a flowchart illustrating filter clogging determination control according to the present embodiment performed by the controller 3. The controller 3 executes this routine at a predetermined calculation cycle (for example, 10 ms) during operation of the fuel cell system 100.

  In step S <b> 1, the controller 3 detects the current cathode gas flow rate Qmea from the flow meter 25, the current compressor outlet pressure Pmea from the pressure gauge 27, and the current compressor rotation speed Rmea from the tachometer 28.

  In step S2, the controller 3 refers to the information on the compressor rotation speed Rlim at the time of the filter clogging amount αlim corresponding to each cathode gas flow rate Q and compressor outlet pressure P stored in advance, and detects the detected current cathode The compressor rotation speed Rlim at the filter clogging amount αlim at the gas flow rate Qmea and the compressor outlet pressure Pmea is calculated.

  In step S3, the controller 3 compares the compressor rotation speed Rmea detected in step S1 with the compressor rotation speed Rlim as the filter clogging determination threshold calculated in step S2. If the compressor rotation speed R is lower than the compressor rotation speed Rlim, the controller 3 determines that the filter 24 is not yet clogged and ends the current process. On the other hand, if the compressor rotational speed R is equal to or higher than the compressor rotational speed Rlim, the process of step S4 is performed.

  In step S4, the controller 3 determines that the filter 24 is clogged.

  According to the present embodiment described above, if two parameters are fixed among the three parameters of the cathode gas flow rate Q, the compressor outlet pressure P, and the compressor rotation speed R, the remaining 1 is set according to the filter foreign matter accumulation amount α. Filter clogging was determined using the fact that one parameter changes regularly. The detected value of the tachometer 28 with high detection accuracy is used as one of the three parameters.

  Thereby, compared with the case where filter clogging is determined without using the compressor rotation speed R, filter clogging can be determined with higher accuracy.

  Further, by using a centrifugal compressor as the compressor 26, it is possible to improve the filter clogging determination accuracy. Hereinafter, this reason will be described.

  FIG. 6 is a diagram showing a compressor operation region when the horizontal axis represents the cathode gas flow rate Q and the vertical axis represents the filter pressure loss ΔP. A portion surrounded by a solid line in the figure is a compressor operation region, and a broken line in the region is a constant rotation speed line.

  As shown by the portion surrounded by the alternate long and short dash line in FIG. 6, the centrifugal compressor 26 has a region where the rotational speed greatly changes with respect to the change of the filter pressure loss ΔP when the cathode gas flow rate Q is constant. . Therefore, when the filter clogging determination is performed in that region, the rate of change of each parameter due to the filter clogging is increased, and the detection accuracy of each parameter is improved. Therefore, filter clogging can be determined with higher accuracy by using a centrifugal compressor.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. This embodiment is different from the first embodiment in that the compressor outlet pressure Plim when the filter foreign matter accumulation amount α is the filter clogging amount αlim is calculated based on the detected cathode gas flow rate Q and the compressor rotation speed R. Hereinafter, the difference will be mainly described. In each of the following embodiments, the same reference numerals are used for portions that perform the same functions as those of the first embodiment described above, and repeated descriptions are omitted as appropriate.

  In the present embodiment, it is determined whether the filter 24 is clogged using the relationship shown in FIG.

  Specifically, the compressor outlet pressure Plim when the filter clogging amount is αlim from the relationship shown in FIG. 3 according to the cathode gas flow rate Q and the compressor rotation speed R, in advance, through experiments with an actual machine or desktop simulation, It is stored in the controller 3. Then, based on the cathode gas flow rate Qmea and the compressor rotation speed Rmea actually detected by the flow meter 25 and the rotation speed meter 28, the compressor outlet pressure Plim (filter clogging determination threshold value) when the filter foreign matter accumulation amount α is the filter clogging amount αlim. ) Is calculated. When the compressor outlet pressure Pmea actually detected by the pressure gauge 27 becomes lower than the calculated compressor outlet pressure Plim, it is determined that the filter 24 is clogged. Hereinafter, filter clogging determination control according to this embodiment will be described.

  FIG. 7 is a flowchart illustrating filter clogging determination control according to the present embodiment performed by the controller 3. The controller 3 executes this routine at a predetermined calculation cycle (for example, 10 ms) during operation of the fuel cell system 100.

  In steps S1 and S4, the same processing as that in the first embodiment is performed, and thus the description thereof is omitted here.

  In step S21, the controller 3 refers to the information of the compressor outlet pressure Plim at the time of the filter clogging amount αlim corresponding to the cathode gas flow rate Q and the compressor rotation speed R stored in advance, and detects the detected current cathode gas. The compressor outlet pressure Plim at the filter clogging amount αlim at the flow rate Qmea and the compressor rotation speed Rmea is calculated.

  In step S22, the controller 3 compares the compressor outlet pressure Pmea detected in step S1 with the compressor outlet pressure Plim as the filter clogging determination threshold calculated in step S21. If the compressor outlet pressure Pmea is higher than the compressor outlet pressure Plim, the controller 3 ends the current process on the assumption that the filter 24 is not clogged yet. On the other hand, if the compressor outlet pressure P is equal to or lower than the compressor outlet pressure Plim, the process of step S4 is performed.

  According to the present embodiment described above, filter foreign matter accumulation can be achieved by fixing two parameters among the three parameters of the cathode gas flow rate Q, the compressor outlet pressure P, and the compressor rotation speed R, as in the first embodiment. Filter clogging is determined using the fact that the remaining one parameter changes regularly according to the amount α. The detected value of the tachometer 28 with high detection accuracy is used as one of the three parameters.

  Thereby, it is possible to determine the filter clogging with higher accuracy than when the compressor rotation speed R is not used when determining the filter clogging.

(Third embodiment)
Next, a third embodiment of the present invention will be described. The present embodiment is different from the first embodiment in that the cathode gas flow rate Qlim when the filter foreign matter accumulation amount α is the filter clogging amount αlim is calculated based on the detected compressor outlet pressure P and compressor rotation speed R. Hereinafter, the difference will be mainly described.

  In the present embodiment, it is determined whether the filter 24 is clogged using the relationship shown in FIG.

  Specifically, the cathode gas flow rate Qlim when the filter foreign matter accumulation amount α is the filter clogging amount αlim is determined according to each compressor outlet pressure P and compressor rotational speed R from the relationship shown in FIG. And is stored in the controller 3. Then, based on the compressor outlet pressure Pmea and the compressor rotational speed Rmea actually detected by the pressure gauge 27 and the rotational speed meter 28, the cathode gas flow rate Qlim (filter clogging determination threshold value) when the filter foreign matter accumulation amount α is the filter clogging amount αlim. ) Is calculated. When the cathode gas flow rate Qmea actually detected by the flow meter 25 becomes lower than the calculated cathode gas flow rate Qlim, it is determined that the filter 24 is clogged. Hereinafter, filter clogging determination control according to this embodiment will be described.

  FIG. 8 is a flowchart for explaining filter clogging determination control according to the present embodiment performed by the controller 3. The controller 3 executes this routine at a predetermined calculation cycle (for example, 10 ms) during operation of the fuel cell system 100.

  In steps S1 and S4, the same processing as that in the first embodiment is performed, and thus the description thereof is omitted here.

  In step S31, the controller 3 refers to the information of the cathode gas flow rate Qlim at the time of the filter clogging amount αlim corresponding to the compressor outlet pressure P and the compressor rotational speed R stored in advance, and detects the current compressor outlet detected. The cathode gas flow rate Qlim when the filter foreign matter accumulation amount α is the filter clogging amount αlim at the pressure Pmea and the compressor rotation speed Rmea is calculated.

  In step S32, the controller 3 compares the cathode gas flow rate Qmea detected in step S1 with the cathode gas flow rate Qlim as the filter clogging determination threshold calculated in step S31. If the cathode gas flow rate Qmea is higher than the cathode gas flow rate Qlim, the controller 3 determines that the filter 24 is not yet clogged and ends the current process. On the other hand, if the cathode gas flow rate Qmea is equal to or less than the cathode gas flow rate Qlim, the process of step S4 is performed.

  According to the present embodiment described above, filter foreign matter accumulation can be achieved by fixing two parameters among the three parameters of the cathode gas flow rate Q, the compressor outlet pressure P, and the compressor rotation speed R, as in the first embodiment. Filter clogging is determined using the fact that the remaining one parameter changes regularly according to the amount α. The detected value of the tachometer 28 with high detection accuracy is used as one of the three parameters.

  Thereby, it is possible to determine the filter clogging with higher accuracy than when the compressor rotation speed R is not used when determining the filter clogging.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. This embodiment is different from the first embodiment in that the current filter foreign matter accumulation amount αcal is estimated based on the detected cathode gas flow rate Qmea, compressor outlet pressure Pmea, and compressor rotation speed Rmea. Hereinafter, the difference will be mainly described.

  FIG. 9 is the same diagram as FIG. 2 described above, and shows the relationship between the filter foreign matter accumulation amount α and the compressor rotational speed R when the cathode gas flow rate Q and the compressor outlet pressure P are at a predetermined value. .

  In the present embodiment, the relationship between the filter foreign matter accumulation amount α and the compressor rotational speed R shown in FIG. 9 is obtained in advance according to the cathode gas flow rate Q and the compressor outlet pressure P through experiments with an actual machine and desktop simulation.

  Thus, if the cathode gas flow rate Q and the compressor outlet pressure P are detected, the relationship between the filter foreign matter accumulation amount α corresponding to the detected cathode gas flow rate Qmea and compressor outlet pressure Pmea and the compressor rotation speed R can be known. Then, if the compressor rotational speed Rmea is detected separately, the current filter foreign matter accumulation amount αcal can be estimated from the detected compressor rotational speed Rmea and the relationship shown in FIG.

  Therefore, in the present embodiment, it is determined whether or not the filter 24 is clogged by comparing the filter foreign matter accumulation amount αcal estimated in this way with a preset filter clogging amount αlim (filter clogging determination threshold). To do. Hereinafter, filter clogging determination control according to this embodiment will be described.

  FIG. 10 is a flowchart illustrating filter clogging determination control according to the present embodiment performed by the controller 3. The controller 3 executes this routine at a predetermined calculation cycle (for example, 10 ms) during operation of the fuel cell system 100.

  In steps S1 and S4, the same processing as that in the first embodiment is performed, and thus the description thereof is omitted here.

  In step S41, the controller 3 estimates the current filter foreign matter accumulation amount αcal based on the detected current cathode gas flow rate Qmea, compressor outlet pressure Pmea, and compressor rotation speed Rmea.

  In step S42, the controller 3 compares the estimated filter foreign matter accumulation amount αcal with a preset filter clogging amount αlim as a filter clogging determination threshold value. If the estimated filter foreign matter accumulation amount αcal is smaller than the filter clogging amount αlim, the controller 3 determines that the filter 24 is not yet clogged and ends the current process. On the other hand, if the estimated filter foreign matter accumulation amount αcal is equal to or greater than the filter clogging amount αlim, the process of step S4 is performed.

  According to the present embodiment described above, the current filter foreign matter accumulation amount αcal is directly estimated based on the detected current cathode gas flow rate Qmea, compressor outlet pressure Pmea, and compressor rotation speed Rmea. Also in this case, since the detection value of the tachometer 28 with high detection accuracy is used to estimate the filter foreign matter accumulation amount αcal, the filter clogging is determined with higher accuracy than when the compressor rotation speed R is not used. can do.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described. This embodiment is different from the fourth embodiment in that the filter pressure loss ΔP is estimated based on the estimated filter foreign matter accumulation amount α. Hereinafter, the difference will be mainly described.

  FIG. 11 is a diagram showing the relationship between the filter foreign matter accumulation amount α and the filter pressure loss ΔP.

  As shown in FIG. 11, the filter pressure loss ΔP regularly changes according to the filter foreign matter accumulation amount α, and increases as the filter foreign matter accumulation amount α increases.

  Therefore, in the present embodiment, the relationship shown in FIG. 11 is obtained in advance by an experiment with an actual machine or a desktop simulation, and the filter pressure loss ΔPlim (filter clogging determination threshold value) when the filter foreign matter accumulation amount α becomes the filter clogging amount αlim. )

  The current filter pressure loss ΔPcal is calculated with reference to FIG. 11 from the current filter foreign matter accumulation amount αcal estimated based on the detected current cathode gas flow rate Qmea, compressor outlet pressure Pmea, and compressor rotation speed Rmea. Filter clogging is determined by comparing with the filter pressure loss ΔPlim. Hereinafter, filter clogging determination control according to this embodiment will be described.

  FIG. 12 is a flowchart illustrating filter clogging determination control according to the present embodiment performed by the controller 3. The controller 3 executes this routine at a predetermined calculation cycle (for example, 10 ms) during operation of the fuel cell system 100.

  In step S1 and step S4, the same processing as that of the first embodiment is performed, and in step S41, the same processing as that of the fourth embodiment is performed.

  In step S51, the controller 3 calculates a filter pressure loss ΔPcal with reference to FIG. 11 based on the estimated filter foreign matter accumulation amount αcal.

  In step S52, the controller 3 compares the calculated filter pressure loss ΔPcal with a preset filter pressure loss ΔPlim as a filter clogging determination threshold. If the calculated filter pressure loss ΔPcal is smaller than the filter pressure loss ΔPlim, the controller 3 determines that the filter 24 is not yet clogged and ends the current process. On the other hand, if the calculated filter pressure loss ΔPcal is greater than or equal to the filter pressure loss ΔPlim, the process of step S4 is performed.

  According to the present embodiment described above, the current filter foreign matter accumulation amount αcal is directly estimated based on the detected current cathode gas flow rate Qmea, compressor outlet pressure Pmea, and compressor rotation speed Rmea. Then, the filter pressure loss ΔPcal is calculated based on the estimated filter foreign matter accumulation amount αcal, and this is compared with a preset filter pressure loss ΔPlim to determine filter clogging. Also in this case, since the detection value of the tachometer 28 with high detection accuracy is used to estimate the filter foreign matter accumulation amount αcal, the filter clogging is determined with higher accuracy than when the compressor rotation speed R is not used. can do.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described. In the present embodiment, it is determined whether or not the filter 24 is clogged when two parameters to be fixed among the three parameters of the cathode gas flow rate Q, the compressor outlet pressure P, and the compressor rotation speed R are in a quasi-steady state. This is different from the first embodiment. Hereinafter, the difference will be mainly described.

  FIG. 13 is a diagram illustrating a quasi-steady state.

  As shown in FIG. 13, the quasi-steady state is based on the required power generation amount of the fuel cell stack 1 in which two parameters to be fixed (in this embodiment, the cathode gas flow rate Q and the compressor outlet pressure P). It means a state in which it is within a predetermined time in the vicinity of the target values Qd and Pd calculated for each parameter. Furthermore, even in one of the two parameters to be fixed, the state deviating from the vicinity of the target values Qd and Pd calculated for each parameter based on the required power generation amount of the fuel cell stack 1 is not a quasi-steady state. . The target value is a target value of each parameter for setting the power generation amount of the fuel cell stack 1 to the required power generation amount. The vicinity of the target value refers to a range from a lower limit value that is smaller than the target value by the predetermined value δ to an upper limit value that is larger than the target value by the predetermined value δ, with the target value as the median value.

  As described above, the determination accuracy can be further improved by determining whether or not the filter 24 is clogged in a quasi-steady state in which the fluctuations of the two parameters to be fixed are small. Hereinafter, filter clogging determination control according to this embodiment will be described.

  FIG. 14 is a flowchart for explaining filter clogging determination control according to the present embodiment performed by the controller 3. The controller 3 executes this routine at a predetermined calculation cycle (for example, 10 ms) during operation of the fuel cell system 100.

  In steps S1 to S4, the same processing as that in the first embodiment is performed, and thus the description thereof is omitted here.

  In step S61, the controller 3 calculates target values of two parameters to be fixed based on the required power generation amount of the fuel cell system 100. In the present embodiment, the cathode gas flow rate Q and the compressor outlet pressure P are used as two parameters to be fixed, so the cathode gas flow rate target value Qd and the compressor outlet pressure target value Pd are calculated.

  In step S62, the controller 3 determines whether the detected cathode gas flow rate Qmea is within the vicinity of the cathode gas flow rate target value Qd. Specifically, the absolute value of the value obtained by subtracting the cathode gas flow rate target value Qd from the detected cathode gas flow rate Qmea is compared with the first predetermined value δa. The controller 3 performs the process of step S63 if the absolute value is equal to or less than the first predetermined value δa, and performs the process of step S64 if the absolute value is greater than the first predetermined value δa.

  In step S63, the controller 3 calculates a time t1 when the absolute value is equal to or less than the first predetermined value δa. Specifically, it is calculated by adding the calculation cycle Δt (10 ms) to the previously calculated t1.

  In step S64, the controller 3 returns the time t1 to zero.

  In step S65, the controller 3 determines whether the detected compressor outlet pressure Pmea is within the vicinity of the compressor outlet pressure target value Pd. Specifically, an absolute value obtained by subtracting the compressor outlet pressure target value Pd from the detected compressor outlet pressure Pmea is compared with the second predetermined value δb. If the absolute value is equal to or smaller than the second predetermined value δb, the controller 3 performs the process of step S66, and if the absolute value is greater than the second predetermined value δb, performs the process of step S67.

  Note that the first predetermined value δa and the second predetermined value δb may be determined according to each parameter.

  In step S66, the controller 3 calculates a time t2 when the absolute value is equal to or less than the second predetermined value δb. Specifically, it is calculated by adding the calculation cycle Δt (10 ms) to t2 calculated last time.

  In step S67, the controller 3 returns the time t2 to zero.

  In step S68, the controller 3 determines whether the two parameters to be fixed are in a quasi-steady state. Specifically, it is determined whether the time t1 and the time t2 have exceeded a predetermined time tconst. If the time t1 and the time t2 respectively exceed the predetermined time tconst, the controller 3 determines that it is a quasi-steady state and performs the process of step S2, and otherwise ends the current process.

  In the present embodiment, the predetermined time tconst is the same for the two parameters, but may be set separately for each parameter. Further, in the present embodiment, the cathode gas flow rate Q and the compressor outlet pressure P are used as the two parameters to be fixed, and the cathode gas flow rate Q is first determined, and then the compressor outlet pressure P is described. Further, it may be simultaneously determined whether the cathode gas flow rate Q and the compressor outlet pressure P are within the range of the first predetermined value δa and the second predetermined value δb, and whether or not the predetermined time tconst has been exceeded. .

  According to this embodiment described above, filter clogging is determined when two parameters to be fixed are in a quasi-steady state, that is, when each parameter is in a static state. Therefore, since the determination is not performed at the time of a transition with a large parameter fluctuation, it is possible to prevent erroneous determination, and it is possible to further improve the determination accuracy of filter clogging.

(Seventh embodiment)
Next, a seventh embodiment of the present invention will be described. This embodiment is different from the sixth embodiment in that it is determined whether or not the fuel cell system 100 has entered a predetermined operation scene. Hereinafter, the difference will be mainly described.

  The operating scenes in which the two fixed parameters are likely to be in a quasi-steady state include a system stop including an idle stop, a system start including a return from an idle stop, and a system warm-up for warming up the fuel cell stack 1. is there. Therefore, in the present embodiment, it is determined whether or not the filter 24 is clogged in an operation scene in which the two fixed parameters tend to be in a quasi-steady state. Hereinafter, filter clogging determination control according to this embodiment will be described.

  FIG. 15 is a flowchart for explaining filter clogging determination control according to the present embodiment performed by the controller 3. The controller 3 executes this routine at a predetermined calculation cycle (for example, 10 ms) during operation of the fuel cell system 100.

  In steps S1 to S4, processing similar to that of the first embodiment is performed, and in steps S61 to S68, processing similar to that of the sixth embodiment is performed. Therefore, description thereof is omitted here.

  In step S <b> 71, the controller 3 determines whether or not the two parameters to be fixed have entered a predetermined driving scene that tends to be in a quasi-steady state. Specifically, it is determined whether the current operation scene is any of when the system is stopped, when the system is activated, and when the system is warmed up. If the current driving scene is a predetermined driving scene, the controller 3 performs the process of step S1, otherwise ends the current process.

  According to the present embodiment described above, filter clogging is determined only in a predetermined operation scene in which two parameters to be fixed tend to be in a quasi-steady state. Therefore, highly accurate determination can be performed without increasing the number of determinations unnecessarily.

(Eighth embodiment)
Next, an eighth embodiment of the present invention will be described. This embodiment is different from the first embodiment in that the compressor rotation speed Rlim when the filter foreign matter accumulation amount α is the filter clogging amount αlim is corrected according to the atmospheric pressure Patm and the intake air temperature Tin. Hereinafter, the difference will be mainly described.

  The compressor rotation speed Rlim when the filter foreign matter accumulation amount α is the filter clogging amount αlim varies depending on the atmospheric pressure Patm and the intake air temperature Tin. Therefore, in the present embodiment, the atmospheric pressure Patm and the intake air temperature Tin are detected, and the compressor rotation speed Rlim is corrected according to the detected values.

  FIG. 16 is a diagram showing the relationship between the compressor rotation speed Rlim and the atmospheric pressure Patm.

  As shown in FIG. 16, the compressor rotation speed Rlim tends to decrease as the atmospheric pressure increases.

  FIG. 17 is a diagram showing the relationship between the compressor rotation speed Rlim and the intake air temperature Tin.

  As shown in FIG. 17, the compressor rotation speed Rlim tends to increase as the intake air temperature increases.

  FIG. 18 is a flowchart illustrating filter clogging determination control according to the present embodiment performed by the controller 3. The controller 3 executes this routine at a predetermined calculation cycle (for example, 10 ms) during operation of the fuel cell system 100.

  In steps S1 to S4, the same processing as that in the first embodiment is performed, and thus the description thereof is omitted here.

  In step S81, the controller 3 detects the atmospheric pressure Patm and the intake air temperature Tin.

  In step S82, the controller 3 corrects the compressor rotational speed Rlim by comprehensively considering the effects of the atmospheric pressure Patm and the intake air temperature Tin based on the relationship shown in FIGS.

  According to the present embodiment described above, the compressor rotation speed Rlim is corrected according to the atmospheric pressure Patm and the intake air temperature Tin, so that the filter clogging determination accuracy can be further improved.

(Ninth embodiment)
Next, a ninth embodiment of the present invention will be described. This embodiment is different from the second embodiment in that the compressor outlet pressure Plim when the filter foreign matter accumulation amount α is the filter clogging amount αlim is corrected according to the atmospheric pressure Patm. Hereinafter, the difference will be mainly described.

  The compressor outlet pressure Plim when the filter foreign matter accumulation amount α is the filter clogging amount αlim varies according to the atmospheric pressure Patm. Therefore, in the present embodiment, the compressor outlet pressure Plim is corrected according to the detected atmospheric pressure Patm.

  FIG. 19 is a diagram showing the relationship between the compressor outlet pressure Plim and the atmospheric pressure Patm.

  As shown in FIG. 19, the compressor outlet pressure Plim tends to decrease as the atmospheric pressure Patm increases.

  FIG. 20 is a flowchart for explaining filter clogging determination control according to the present embodiment performed by the controller 3. The controller 3 executes this routine at a predetermined calculation cycle (for example, 10 ms) during operation of the fuel cell system 100.

  In steps S1 to S4, the same processing as that in the first embodiment is performed, and thus the description thereof is omitted here.

  In step S91, the controller 3 detects the atmospheric pressure Patm.

  In step S92, the controller 3 corrects the compressor outlet pressure Plim with reference to FIG. 19 based on the detected atmospheric pressure Patm.

  According to the present embodiment described above, the compressor rotation speed Rlim is corrected according to the detected atmospheric pressure Patm, so that the filter clogging determination accuracy can be further improved.

(10th Embodiment)
Next, a tenth embodiment of the present invention will be described. This embodiment is different from the third embodiment in that the cathode gas flow rate Qlim when the filter foreign matter accumulation amount α is the filter clogging amount αlim is corrected according to the atmospheric pressure Patm and the intake air temperature Tin. Hereinafter, the difference will be mainly described.

  The cathode gas flow rate Qlim when the filter foreign matter accumulation amount α is the filter clogging amount αlim varies depending on the atmospheric pressure Patm and the intake air temperature Tin. Therefore, in the present embodiment, the atmospheric pressure Patm and the intake air temperature Tin are detected, and the cathode gas flow rate Qlim is corrected according to the detected values.

  FIG. 21 is a diagram showing the relationship between the cathode gas flow rate Qlim and the atmospheric pressure Patm.

  As shown in FIG. 21, the cathode gas flow rate Qlim tends to decrease as the atmospheric pressure Patm increases.

  FIG. 22 is a diagram showing the relationship between the cathode gas flow rate Qlim and the intake air temperature Tin.

  As shown in FIG. 22, the cathode gas flow rate Qlim tends to increase as the intake air temperature Tin increases.

  FIG. 23 is a flowchart illustrating filter clogging determination control according to the present embodiment performed by the controller 3. The controller 3 executes this routine at a predetermined calculation cycle (for example, 10 ms) during operation of the fuel cell system 100.

  In steps S1 to S4, the same processing as that in the first embodiment is performed, and thus the description thereof is omitted here.

  In step S101, the controller 3 detects the atmospheric pressure Patm and the intake air temperature Tin.

  In step S102, the controller 3 corrects the cathode gas flow rate Qlim by comprehensively considering the effects of the atmospheric pressure Patm and the intake air temperature Tin based on the relationship of FIG. 21 and FIG.

  According to the present embodiment described above, the cathode gas flow rate Qlim is corrected according to the atmospheric pressure Patm and the intake air temperature Tin, so that the filter clogging determination accuracy can be further improved.

(Eleventh embodiment)
Next, an eleventh embodiment of the present invention will be described. This embodiment is different from the first embodiment in that the filter 24 is determined to be clogged when the compressor rotation speed R becomes equal to or higher than the compressor rotation speed Rlim. Hereinafter, the difference will be mainly described.

  FIG. 24 is a flowchart illustrating filter clogging determination control according to this embodiment performed by the controller 3. The controller 3 executes this routine at a predetermined calculation cycle (for example, 10 ms) during operation of the fuel cell system 100.

  In steps S1 to S4, the same processing as that in the first embodiment is performed, and thus the description thereof is omitted here.

  In step S111, the controller 3 calculates the number of times (hereinafter referred to as “the number of times of filter clogging”) N that the compressor rotational speed R becomes equal to or higher than the compressor rotational speed Rlim. Specifically, 1 is added to N every time the compressor rotational speed R becomes equal to or higher than the compressor rotational speed Rlim.

  In step S112, the controller 3 determines whether the filter clogging number N has exceeded a predetermined number. The controller 3 performs the process of step S113 if the filter clogging number N exceeds the predetermined number, otherwise ends the current process.

  In step S113, the controller 3 returns N to zero.

  According to the present embodiment described above, by performing filter clogging determination a plurality of times, erroneous determination due to sensor noise or the like that may occur in the case of a single time can be prevented, so that filter clogging determination accuracy is further improved. be able to.

(Twelfth embodiment)
Next, a twelfth embodiment of the present invention will be described. This embodiment is different from the first embodiment in that a warning is displayed to the driver when it is determined that the filter is clogged. Hereinafter, the difference will be mainly described.

  FIG. 25 is a flowchart illustrating filter clogging determination control according to this embodiment performed by the controller 3. The controller 3 executes this routine at a predetermined calculation cycle (for example, 10 ms) during operation of the fuel cell system 100.

  In steps S1 to S4, the same processing as that in the first embodiment is performed, and thus the description thereof is omitted here.

  In step S121, the controller 3 turns on a warning lamp and displays a warning to the driver.

  According to the present embodiment described above, since it is possible to notify the driver when it is determined that the filter is clogged, it is possible to prompt the driver to replace the filter 24.

  Note that the present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  For example, when the parameters that make it easy to determine filter clogging vary depending on the compressor operating region, each of the three parameters changes arbitrarily, depending on the operating region of the compressor 26, and the filter clogging is determined. You may do it.

  In addition, there are cases where parameters that make it easy to determine filter clogging may vary depending on the type of compressor 26. In this case, two parameters to be fixed may be selected according to the type of compressor 26.

  In each of the above embodiments, the compressor rotation speed Rmea detected by the rotation speed meter 28 is used. However, instead of this, a command rotation speed for the compressor 26 may be used. Thereby, clogging of the filter can be determined even when the rotation speed meter 28 is broken.

  In the sixth embodiment, the fixed parameters for determining the quasi-steady state are the cathode gas flow rate Q and the compressor outlet pressure P. However, the cathode gas flow rate Q and the compressor rotational speed R may be used. The rotational speed R may be used.

  In the eighth and tenth embodiments, the filter clogging determination threshold value is corrected in consideration of the influence of both the atmospheric pressure Patm and the intake air temperature Tin. However, the filter clogging determination threshold value may be corrected based on only one of them.

  In the eleventh embodiment, it is determined that the filter is clogged when the number of times of filter clogging exceeds a predetermined number of times. Of the number of comparisons between the compressor rotation speed R and the compressor rotation speed Rlim, Filter clogging may be determined when the number of times the compressor rotational speed Rlim is exceeded exceeds a predetermined ratio.

  In the eleventh embodiment, multiple comparisons may be made for each specific scene such as start-up, warm-up, idle stop or return during one trip, or stop during different trips. You may compare every hour.

1 Fuel cell stack (fuel cell)
24 Filter 26 Compressor 28 Tachometer 100 Fuel cell system S1 Flow rate detection means, pressure detection means, rotation speed detection means S2, S21, S31 Threshold value calculation means S3, S22, S32, S42, S52 Filter clogging determination means S41 Foreign matter accumulation amount Estimating means S51 Pressure loss estimating means S61 Target value calculating means S68 Quasi-steady state determining means S81, S91, S101 Atmospheric pressure detecting means, intake air temperature detecting means S82, S92, S102 Correction means

Claims (11)

A fuel cell that generates power by receiving supply of anode gas and cathode gas;
A compressor for supplying a cathode gas to the fuel cell;
A filter provided upstream of the compressor to remove foreign matter in the cathode gas supplied to the fuel cell;
A fuel cell system comprising:
Flow rate detection means for detecting the flow rate of the cathode gas discharged from the compressor;
Pressure detecting means for detecting the pressure of the cathode gas discharged from the compressor;
A rotational speed detecting means for detecting the rotational speed of the compressor;
Threshold calculation means for calculating a filter clogging determination threshold for the remaining parameters based on detection values of two parameters of the flow rate, the pressure, and the rotation speed;
A filter clogging determination means for comparing the detected value of the remaining parameter with the filter clogging determination threshold value to determine whether the filter is clogged;
A fuel cell system comprising: A target value calculation means for calculating a target value to be reached by the two parameters based on the required power generation amount of the fuel cell;
Quasi-stationary state determination means for determining whether the detected values of the two parameters are in a quasi-stationary state within a range near the target value for a predetermined time;
With
The threshold value calculation means calculates a filter clogging determination threshold value for the remaining parameters when it is determined as a quasi-steady state.
The fuel cell system according to claim 1. The quasi-steady state determination means determines whether the operation scene of the fuel cell system is in a quasi-steady state when the operation scene of the fuel cell system is in at least one operation scene during startup, stop, and warm-up.
The fuel cell system according to claim 2. Atmospheric pressure detection means for detecting atmospheric pressure;
Intake air temperature detecting means for detecting the temperature of the cathode gas sucked by the compressor;
Correction means for correcting the filter determination threshold based on one or both of the atmospheric pressure and the temperature;
The fuel cell system according to any one of claims 1 to 3, further comprising: The filter clogging determining means determines whether or not the filter is clogged by comparing the detected value of the remaining parameter with the filter clogging determination threshold value a plurality of times.
The fuel cell system according to any one of claims 1 to 4, wherein the fuel cell system is provided. The rotational speed detecting means detects the rotational speed of the compressor by means of a rotational speed meter;
The fuel cell system according to any one of claims 1 to 5, wherein: The rotational speed detection means detects a command rotational speed for the compressor as a rotational speed of the compressor.
The fuel cell system according to any one of claims 1 to 5, wherein: When it is determined that the filter is clogged, warning means for warning that the filter is clogged is provided.
The fuel cell system according to any one of claims 1 to 7, wherein The compressor is a centrifugal compressor.
The fuel cell system according to any one of claims 1 to 8, wherein A fuel cell that generates power by receiving supply of anode gas and cathode gas;
A compressor for supplying a cathode gas to the fuel cell;
A filter provided upstream of the compressor to remove foreign matter in the cathode gas supplied to the fuel cell;
A fuel cell system comprising:
Flow rate detection means for detecting the flow rate of the cathode gas discharged from the compressor;
Pressure detecting means for detecting the pressure of the cathode gas discharged from the compressor;
A rotational speed detecting means for detecting the rotational speed of the compressor;
Foreign matter accumulation amount estimation means for estimating the foreign matter accumulation amount of the filter based on the detected values of the three parameters of the flow rate, the pressure, and the rotation speed;
A filter clogging determination means for comparing the foreign matter accumulation amount with a predetermined filter clogging determination threshold value to determine whether or not the filter is clogged;
A fuel cell system comprising: A fuel cell that generates power by receiving supply of anode gas and cathode gas;
A compressor for supplying a cathode gas to the fuel cell;
A filter provided upstream of the compressor to remove foreign matter in the cathode gas supplied to the fuel cell;
A fuel cell system comprising:
Flow rate detection means for detecting the flow rate of the cathode gas discharged from the compressor;
Pressure detecting means for detecting the pressure of the cathode gas discharged from the compressor;
A rotational speed detecting means for detecting the rotational speed of the compressor;
Foreign matter accumulation amount estimation means for estimating the foreign matter accumulation amount of the filter based on the detected values of the three parameters of the flow rate, the pressure, and the rotation speed;
Pressure loss estimation means for estimating pressure loss before and after the filter based on the amount of accumulated foreign matter,
A filter clogging determination means for comparing the pressure loss with a predetermined filter clogging determination threshold value to determine whether the filter is clogged;
A fuel cell system comprising:

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