WO2024069735A1 - 燃料電池の劣化判定装置および燃料電池車 - Google Patents
燃料電池の劣化判定装置および燃料電池車 Download PDFInfo
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- WO2024069735A1 WO2024069735A1 PCT/JP2022/035874 JP2022035874W WO2024069735A1 WO 2024069735 A1 WO2024069735 A1 WO 2024069735A1 JP 2022035874 W JP2022035874 W JP 2022035874W WO 2024069735 A1 WO2024069735 A1 WO 2024069735A1
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- fuel cell
- deterioration
- catalyst
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- deterioration determination
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04298—Processes for controlling fuel cells or fuel cell systems
- H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
- H01M8/04537—Electric variables
- H01M8/04634—Other electric variables, e.g. resistance or impedance
- H01M8/04649—Other electric variables, e.g. resistance or impedance of fuel cell stacks
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
- B60L58/30—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling fuel cells
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
- B60L58/40—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for controlling a combination of batteries and fuel cells
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04298—Processes for controlling fuel cells or fuel cell systems
- H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
- H01M8/04537—Electric variables
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04298—Processes for controlling fuel cells or fuel cell systems
- H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
- H01M8/04664—Failure or abnormal function
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04298—Processes for controlling fuel cells or fuel cell systems
- H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
- H01M8/04664—Failure or abnormal function
- H01M8/04679—Failure or abnormal function of fuel cell stacks
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M2008/1095—Fuel cells with polymeric electrolytes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2250/00—Fuel cells for particular applications; Specific features of fuel cell system
- H01M2250/20—Fuel cells in motive systems, e.g. vehicle, ship, plane
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Definitions
- This disclosure relates to, for example, a fuel cell deterioration determination device and a fuel cell vehicle equipped with this deterioration determination device.
- Mobility is essential in modern society, and various vehicles such as automobiles travel the roads on a daily basis.
- fuel cells which have a relatively small environmental impact, are attracting attention as a new power source to supply driving force to vehicles.
- fuel gas hydrogen
- oxygen oxygen
- air electrode oxygen
- electrical energy is obtained through a chemical reaction between these. Therefore, in order to continuously obtain an appropriate amount of electrical energy (generated power) from the fuel cell, it is necessary to properly determine whether the fuel cell installed in the vehicle has deteriorated.
- One of the components that make up a fuel cell is an electrode catalyst (hereinafter simply referred to as "catalyst").
- a catalyst is in the form of a catalyst metal such as platinum bonded to a catalyst carrier such as carbon.
- an activation overvoltage is calculated based on the amount of electricity generated when the catalyst in each cell that makes up the fuel cell is reduced, and the FC voltage is estimated from the activation overvoltage calculated.
- Patent Document 1 proposes comparing the estimated FC voltage with the actual FC voltage detected by a voltage sensor, and judging the deterioration of the fuel cell based on the comparison result.
- Patent Document 2 also focuses on the water content in the fuel cell as a criterion for determining deterioration, and proposes estimating the water content by determining the proton transfer resistance and gas reaction resistance using a Cole-Cole plot, which is a characteristic diagram showing the relationship between frequency and impedance on a complex plane.
- the present disclosure has been made in consideration of the above-mentioned problems as an example, and aims to provide a fuel cell degradation determination device and a fuel cell vehicle that can determine whether degradation is progressing in the fuel cell's catalytic metal or catalyst carrier.
- a fuel cell deterioration determination device that determines the deterioration of a catalyst in a fuel cell stack, including a catalytic metal and a catalyst carrier that supports the catalytic metal, and includes an impedance measurement unit that applies an AC signal to the fuel cell stack to measure the AC impedance of the fuel cell stack, and a deterioration determination unit that estimates the degree of activation overvoltage in the fuel cell stack as deterioration of the catalytic metal and estimates the degree of diffusion overvoltage as deterioration of the catalyst carrier based on characteristics of the measured AC impedance, and determines the degree of deterioration of the catalytic metal and the catalyst carrier based on previously stored reference values of activation overvoltage and diffusion overvoltage for the vehicle mileage.
- FIG. 1 is a schematic diagram showing an example of the configuration of a fuel cell vehicle equipped with a fuel cell deterioration determination device according to a first embodiment
- FIG. 2 is a schematic diagram illustrating the configurations and functions of the fuel cell vehicle according to the first embodiment.
- 2 is a schematic diagram showing an example of the configuration of a control device that also functions as a deterioration determination device according to the first embodiment;
- FIG. 3 is a flowchart showing a method for determining catalyst deterioration of a fuel cell according to the first embodiment.
- FIG. 2 is a schematic diagram showing an example of a Cole-Cole plot diagram of the fuel cell stack according to the first embodiment.
- FIG. 6 is a schematic diagram showing an example of a case where the high-frequency side semicircle is changed in the Cole-Cole plot shown in FIG. 5 .
- FIG. 6 is a schematic diagram showing an example of a case where the low-frequency semicircle is changed in the Cole-Cole plot shown in FIG. 5 .
- 11 is an example of table data showing a correspondence relationship between a travel distance and a high-frequency side semicircle and a low-frequency side semicircle.
- 4 is an example showing the time transition of cell voltage during acceleration and deceleration in a fuel cell vehicle.
- 13 is an example showing the time transition of the cell voltage in a case where a catalyst carrier deterioration suppression mode (part 1) after deterioration determination is applied.
- FIG. 13 is an example showing the time transition of the cell voltage in a case where a catalyst carrier deterioration suppression mode (part 2) after deterioration determination is applied. 13 is an example showing the time transition of the cell voltage in a case where a catalytic metal deterioration suppression mode is applied after deterioration is determined.
- FIG. 11 is a schematic diagram showing an example of a catalyst deterioration determination diagram for a fuel cell stack according to a second embodiment
- FIG. 14 is a schematic diagram showing an example of a case where the high frequency side plot changes in the catalyst deterioration determination diagram shown in FIG. 13 .
- FIG. 1 and 2 are schematic diagrams showing a configuration example and functional blocks of a fuel cell vehicle FCV equipped with a fuel cell stack FC according to this embodiment.
- this fuel cell vehicle FCV is configured as a four-wheel drive vehicle in which a driving torque output from a driving force source 21 that generates a driving torque for the vehicle is transmitted to a left front wheel 3LF, a right front wheel 3RF, a left rear wheel 3LR, and a right rear wheel 3RR (hereinafter, collectively referred to as "wheels 3" unless a distinction is required).
- the driving force source 21 can be, for example, a known electric motor arranged on the front wheel side.
- the electric motors serving as the driving force source 21 in this embodiment may be arranged one each on the front wheel side and the rear wheel side, or one electric motor may be arranged on each wheel 3.
- the driving force source 21 may further include an internal combustion engine such as a gasoline engine, a diesel engine, or a gas turbine engine.
- the power supply system that supplies the desired power to the driving force source 21 includes a fuel cell stack FC that is configured by stacking multiple known fuel cells, such as PEFCs (polymer electrolyte fuel cells), a hydrogen gas supply unit that includes a known hydrogen tank 23 and piping, an air supply unit that includes a known compressor 31 and piping, a known secondary battery 50 such as a lithium ion secondary battery or a lead storage battery, a known converter 22, and a control device 100 that controls these.
- the control device 100 in this embodiment also functions as a deterioration determination device 10 that determines deterioration of the fuel cell stack FC.
- the fuel cell stack FC and the secondary battery 50 are each capable of supplying power to a load including the electric motor described above.
- the fuel cell stack FC is connected to a load including a driving force source 21 (electric motor) via the above-mentioned converter 22 and wiring. Also as shown in Fig. 2, the current and voltage in the fuel cell stack FC are detected by a well-known current sensor SR1 and voltage sensor SR2 , respectively.
- the converter 22 includes a known AC/DC converter that converts DC current to AC current, and a known DC/DC converter that adjusts the voltage of the DC current to a desired voltage.
- the converter 22 of this embodiment has a function of receiving a control signal from the control device 100 to set the output voltage generated and output by the fuel cell stack FC, and a function of boosting the power generated by the fuel cell stack FC to a desired voltage when supplying it to a load.
- the fuel cell vehicle FCV of this embodiment also includes the above-mentioned driving force source 21, electric steering device 8, and brake devices 4LF, 4RF, 4LR, and 4RR (hereinafter collectively referred to as "brake device 4" unless a distinction is required) as equipment used for driving control.
- the driving force source 21 outputs a driving torque that is transmitted to the front drive shaft 2F and the rear drive shaft 2R via a transmission, a front wheel differential mechanism 5F, and a rear wheel differential mechanism 5R (not shown).
- the driving of the driving force source 21 and the transmission is controlled by a known control device that includes one or more electronic control devices (ECU: Electronic Control Unit).
- the front wheel drive shaft 2F is provided with an electric steering device 8.
- the electric steering device 8 includes an electric motor and a gear mechanism (not shown), and is controlled by the vehicle drive control device 20 to adjust the steering angle of the left front wheel 3LF and the right front wheel 3RF.
- the vehicle drive control device 20 includes one or more known electronic control devices (ECUs) that control the drive of the drive force source 21 that outputs the drive torque of the fuel cell vehicle FCV, the steering wheel 9 or the electric steering device 8 that controls the steering angle of the steering wheels, and the brake device 4 that controls the braking force of the fuel cell vehicle FCV.
- the vehicle drive control device 20 may also have a function of controlling the drive of a transmission that changes the speed of the output output from the drive force source 21 and transmits it to the wheels 3.
- the hydrogen gas stored in the hydrogen tank 23 is supplied to the anode side flow path of the above-mentioned fuel cell stack FC via a hydrogen intake valve 32a having a known structure installed in the hydrogen supply flow path.
- a portion of the hydrogen gas discharged from the fuel cell stack FC may be returned to the hydrogen supply flow path by the circulation flow path and a known circulation pump 45.
- the remaining hydrogen gas discharged from the fuel cell stack FC is diluted by a diluter 41 at a predetermined timing via the opening and closing operation of a known hydrogen exhaust valve 32b under the control of the control device 100, and then released (exhausted) into the atmosphere.
- the air supply unit for supplying oxygen gas (air) to the fuel cell stack FC is configured to include, in addition to the compressor 31 described above, a known oxygen intake valve 32c and an air exhaust valve (back pressure valve) 32d that adjust the amount of oxygen (air) supplied to the fuel cell 1.
- this air supply unit may further include a known flow sensor (not shown) that can measure the flow rate of air supplied to the fuel cell stack FC.
- the air taken in by the compressor 31 is then supplied to the cathode side flow path in the fuel cell stack FC via the oxygen intake valve 32c and a known humidifier (not shown).
- the air supplied to the fuel cell 1 is also supplied to the diluter 41 described above as cathode off-gas under the control of the oxygen exhaust valve (back pressure valve) 32d by the control device 100.
- the control device 100 is configured to include one or more processors (CPU (Central Processing Unit)) and one or more memories communicatively connected to the one or more processors.
- the control device 100 may be configured to be connectable to a known external network NET such as the Internet via various known communication devices CD, such as a form that uses a smartphone, as an example.
- Such a control device 100 is electrically connected, either directly or via a communication means such as a Controller Area Network (CAN) or Local Inter Net (LIN), to a compressor 31, each valve 32 (hydrogen intake valve 32a, hydrogen exhaust valve 32b, oxygen intake valve 32c, and oxygen exhaust valve 32d), and known sensors SR such as a current sensor SR1 and a voltage sensor SR2 .
- a communication means such as a Controller Area Network (CAN) or Local Inter Net (LIN)
- CAN Controller Area Network
- LIN Local Inter Net
- the fuel cell stack FC of this embodiment has a stack structure in which multiple known fuel cell cells, each having an electromotive force of about 1 V, are connected in series and stacked.
- the fuel cell stack FC of this embodiment can be a polymer electrolyte fuel cell (PEFC) in which fuel cell cells are connected in series within a pair of known end plates that hold the fuel cells under pressure at both ends to provide the system voltage required by the fuel cell vehicle FCV.
- PEFC polymer electrolyte fuel cell
- each fuel cell constituting the fuel cell stack FC has a structure in which a known MEA (membrane electrode assembly) is interposed between a pair of known separators installed on the fuel electrode side and the air electrode side, respectively.
- This MEA is configured to include at least a known cathode catalyst layer, a known anode catalyst layer arranged opposite the cathode catalyst layer, and a known polymer electrolyte membrane arranged between the cathode catalyst layer and the anode catalyst layer.
- the membrane electrode assembly may further include a known air electrode side gas diffusion layer and a known fuel electrode side gas diffusion layer.
- the cathode catalyst layer in this embodiment is in a form in which a known catalytic metal, such as precious metal fine particles such as platinum (Pt) nanoparticles or platinum-cobalt (Pt-Co) particles, is bonded to a catalyst carrier, such as a metal material such as stainless steel or titanium, or a carbon material.
- a known catalytic metal such as precious metal fine particles such as platinum (Pt) nanoparticles or platinum-cobalt (Pt-Co) particles
- Pt-Co platinum-cobalt
- a deterioration determination device 10 capable of determining deterioration of a catalyst in the fuel cell stack FC in this embodiment will be described with reference to Fig. 3. That is, the deterioration determination device 10 in this embodiment is configured to have a function of determining deterioration of a catalyst in the fuel cell stack FC, including a catalytic metal and a catalyst carrier supporting the catalytic metal.
- the deterioration determination device 10 includes a current measurement unit 10A, a voltage measurement unit 10B, an impedance measurement unit 10C, and a deterioration determination unit 10D. As described above, the deterioration determination device 10 is configured as one function executed by the control device 100 of this embodiment. As shown in FIG. 3, the control device 100 includes a drive control unit 30 and a presentation control unit 40.
- the current measurement unit 10A is configured to have the function of measuring the current value of the fuel cell stack FC described above. More specifically, the current measurement unit 10A of this embodiment can measure the value of the current flowing through the fuel cell stack FC via the current sensor SR1 described above.
- the voltage measurement unit 10B is configured to have the function of measuring the voltage value of the fuel cell stack FC described above. More specifically, the voltage measurement unit 10B of this embodiment can measure the voltage value applied to the fuel cell stack FC via the voltage sensor SR2 described above.
- the impedance measuring unit 10C is configured to have the function of applying a measurement AC signal to the fuel cell stack FC to measure the AC impedance of the fuel cell stack FC.
- the impedance measuring unit 10C can measure the impedance of the fuel cell stack FC, for example, by a known AC impedance method, based on the current value and voltage value of the fuel cell.
- the deterioration determination unit 10D is configured with the function of determining whether the catalyst of the fuel cell constituting the fuel cell stack FC has deteriorated based on the characteristics of the measured AC impedance. More specifically, the deterioration determination unit 10D of this embodiment can determine whether the catalyst metal or catalyst carrier of the fuel cell has deteriorated by the following procedure.
- the deterioration determination unit 10D calculates a Nyquist diagram based on the AC impedance measured as described above, as shown in FIG.
- the deterioration determination unit 10D defines the arc radius Rh on the high frequency side in the calculated Nyquist diagram as the degree of activation overvoltage, and the arc radius Rl on the low frequency side in the Nyquist diagram as the degree of diffusion overvoltage.
- the deterioration determination unit 10D of this embodiment estimates the degree of activation overvoltage in the fuel cell stack FC as the degree of deterioration of the catalyst metal, and estimates the degree of diffusion overvoltage as the degree of deterioration of the catalyst support.
- reference values for activation overvoltage and diffusion overvoltage with respect to vehicle mileage are stored in advance in the memory device MR. These reference values indicate the standard degree of deterioration of the catalyst metal and catalyst carrier as the mileage is accumulated.
- the deterioration determination unit 10D is capable of reading out the reference values for activation overvoltage and diffusion overvoltage with respect to vehicle mileage by referring to the memory device MR.
- the reference values for activation overvoltage and diffusion overvoltage with respect to vehicle mileage described above can be calculated in advance by experiments or simulations using the vehicle.
- the deterioration determination unit 10D therefore determines the degree of deterioration (which can also be said to be the progress of deterioration) of the catalyst metal and catalyst carrier based on the arc radius (degree of activation overvoltage) on the high frequency side and the arc radius (degree of diffusion overvoltage) on the low frequency side in the calculated Nyquist diagram, and the reference values of activation overvoltage and diffusion overvoltage for the vehicle mileage stored in advance.
- the deterioration determination unit 10D calculates the increased arc radius on the high frequency side.
- a known approximation method can be applied to calculate the arc radius described above, and for example, the arc radius can be obtained using a known approximation method such as the least squares method based on multiple measurement points on the high frequency side of the calculated Nyquist diagram.
- the deterioration determination unit 10D compares the high-frequency side arc radius calculated above with the reference value of the activation overvoltage (high-frequency semicircle diameter) for the vehicle travel distance illustrated in FIG. 8, and calculates the degree to which the calculated high-frequency side arc radius differs from the reference value. For example, when the deterioration determination described above is performed when the fuel cell vehicle FCV has traveled 700 km, the high-frequency side arc radius is compared with the reference value a2.
- the deterioration determination unit 10D can determine that deterioration of the catalyst metal is progressing when, for example, the calculated high-frequency side arc radius exceeds a reference value a2. Note that in this embodiment, it is determined that deterioration is progressing when the calculated high-frequency side arc radius exceeds a reference value, but it may also be possible to determine that deterioration is progressing when the calculated high-frequency side arc radius exceeds a reference value, for example, by setting an appropriate range of several to around 10% of the reference value.
- the deterioration determination unit 10D calculates the increased arc radius on the low-frequency side in the same manner as described above. Then, the deterioration determination unit 10D compares the calculated low-frequency side arc radius with the reference value of the diffusion overvoltage (low-frequency semicircle diameter) for the vehicle travel distance illustrated in Fig. 8, and calculates the degree of difference between the calculated low-frequency side arc radius and the reference value. For example, when the deterioration determination is performed when the fuel cell vehicle FCV has traveled 1700 km, the low-frequency side arc radius is compared with the reference value b4.
- the deterioration determination unit 10D can determine that the deterioration of the catalyst carrier is progressing when, for example, the calculated arc radius on the low frequency side exceeds a reference value b4. Note that in this embodiment, it is determined that deterioration is progressing when the calculated arc radius on the low frequency side exceeds a reference value, but it may also be possible to determine that deterioration is progressing when the calculated arc radius exceeds a reference value, for example, by setting an appropriate range of several to around 10% of the reference value.
- the drive control unit 30 is configured with the function of controlling the drive of the fuel cell stack FC. More specifically, if the deterioration determination unit 10D determines that the catalyst carrier is deteriorating (i.e., the rate of deterioration is faster on the diffusion overvoltage side), the drive control unit 30 may reduce the rate of change of voltage per unit time during acceleration/deceleration operation of the fuel cell vehicle FCV. More specifically, if the rate of change of voltage per unit time as shown in FIG. 9 is set to the standard state, for example, the drive control unit 30 may perform control to reduce the rate of change of voltage per unit time during acceleration/deceleration operation of the fuel cell vehicle FCV, as shown in FIG. 10.
- the drive control unit 30 may control the timing of introducing air into the cathode electrode at the start of the fuel cell stack FC to be delayed from the normal time, as shown in FIG. 11. More specifically, when the deterioration is at a normal rate, as shown in FIG. 11, when the fuel cell vehicle FCV system is turned on and a request to start the fuel cell stack FC is generated at time t1, hydrogen gas is normally supplied to the anode side flow path via the hydrogen intake valve 32a at time t2, and then air is supplied to the cathode side flow path via the oxygen intake valve 32c at time t3. On the other hand, when it is determined that the catalyst carrier is deteriorated, the drive control unit 30 can execute control to delay the supply of air to the cathode side flow path until time t4, which is later than time t3.
- the degree of delay from time t3 to time t4 may be set, for example, according to the degree of deterioration of the catalyst carrier.
- the drive control unit 30 can set time t4 with a larger degree of delay as the degree of deterioration of the catalyst carrier increases.
- the drive control unit 30 can execute control to suppress the upper limit voltage value of the fuel cell stack FC used in the fuel cell vehicle FCV, as illustrated in FIG. 12. More specifically, if the upper limit voltage value of the fuel cell stack FC is set to V0 when the rate of deterioration is standard, the drive control unit 30 can set the upper limit voltage value to V1, lowering it by Vd from V0. The degree of voltage drop Vd may be set as appropriate depending on the vehicle model, the specifications of the electric motor, etc.
- the drive control unit 30 may suppress the upper limit voltage value of the fuel cell stack FC used in the fuel cell vehicle FCV in accordance with the deterioration on the activation voltage side. More specifically, when comparing the arc radius on the high frequency side with a reference value corresponding to the mileage at that time, the greater the degree of exceedance from the reference value, the greater the suppression of the above-mentioned upper limit voltage value.
- the presentation control unit 40 executes a process of presenting various information, such as the deterioration state of the fuel cell stack FC, via a presentation device DD, which includes a publicly known in-vehicle speaker SP and display DP.
- the presentation control unit 40 may present the above-mentioned various information to the occupant via the in-vehicle presentation device DD, or may access and present the information on an external terminal, such as a smartphone, carried by the occupant.
- the deterioration suppression method may be used as an algorithm of a computer-readable program.
- a program having such an algorithm may be distributed so as to be downloadable to a fuel cell vehicle FCV via a known network, or may be distributed in the form of being stored on a recording medium.
- the user activates the system of the fuel cell vehicle FCV and starts driving.
- step 1 the control device 100 determines whether the deterioration determination condition for the fuel cell stack FC is satisfied. More specifically, the control device 100 may determine whether the fuel cell stack FC has reached an appropriate temperature based on a known temperature sensor (not shown) to determine whether the fuel cell stack FC is in a state where it can be stably operated. Furthermore, the control device 100 may determine whether the moisture content state of the fuel cell stack FC has reached an appropriate state based on a known moisture content measurement method exemplified in, for example, Patent Document 2.
- step 1 the control device 100 determines whether the carrier deterioration suppression condition is met. More specifically, in step 2A, the deterioration determination unit 10D calculates a Nyquist diagram based on the measured AC impedance. Next, using the calculated Nyquist diagram and a reference value stored in the memory device MR, the deterioration determination unit 10D determines the degree of deterioration of the catalyst carrier by finding the difference between the low-frequency side arc radius (degree of diffusion overvoltage) and the reference value.
- step 2A If it is determined in step 2A that the deterioration of the catalyst carrier is more advanced than the reference value (Yes in step 2A), the process proceeds to step 2B, where the carrier deterioration suppression process is executed. That is, in step 2B, the control device 100 (drive control unit 30) can execute at least one of the following: ( ⁇ ) control to reduce the rate of change of voltage per unit time during acceleration/deceleration operation of the fuel cell vehicle FCV as exemplified in FIG. 10; and ( ⁇ ) control to delay the timing of introducing air into the cathode electrode at the start of the fuel cell stack FC from the normal time as exemplified in FIG. 11.
- step 2A determines whether the deterioration of the catalyst carrier is within the reference value range (deterioration is less advanced than expected) (No in step 2A). That is, in step 3A, the deterioration determination unit 10D described above calculates a Nyquist diagram based on the measured AC impedance. Next, using the calculated Nyquist diagram and the reference value stored in the memory device MR, the deterioration determination unit 10D determines the degree of deterioration of the catalyst metal by finding the difference between the high frequency side arc radius (degree of activation overvoltage) and the reference value.
- step 3A If it is determined in step 3A that the deterioration of the catalytic metal is more advanced than the reference value (Yes in step 3A), the process proceeds to step 3B, where catalytic metal deterioration suppression processing is executed. That is, in step 3B, the control device 100 (drive control unit 30) can execute control to suppress the upper limit voltage value of the fuel cell stack FC used in the fuel cell vehicle FCV, as exemplified in FIG. 12.
- step 4 the control device 100 determines whether the fuel cell vehicle FCV system has been turned OFF, and if it has not yet been turned OFF (No in step 4), it returns to step 1 and repeats the above-described process. On the other hand, if the fuel cell vehicle FCV system has been turned OFF in step 4 (Yes in step 4), the above-described method for suppressing deterioration of the catalyst metal and catalyst carrier is terminated.
- the above-described method for suppressing deterioration of the catalyst metal and catalyst carrier makes it possible to distinguish between deterioration of the catalyst metal and catalyst carrier using the high-frequency arc radius (degree of activation overvoltage) and the low-frequency arc radius (degree of diffusion overvoltage) derived from the Nyquist diagram. Furthermore, according to the control device 100 of this embodiment, if corrosion progresses at a rate faster than expected in either of these, for example, it is possible to suppress the progression of deterioration in the catalyst by modifying the operating parameters of the fuel cell described above.
- the computer program that realizes each of the functions of the deterioration determination device 10 described above is a computer program applied to a fuel cell deterioration determination device that determines the deterioration of a catalyst including a catalytic metal in a fuel cell stack and a catalyst carrier supporting the catalytic metal, and can cause one or more processors to execute processes including applying an AC signal to the fuel cell stack to measure the AC impedance of the fuel cell stack, estimating the degree of activation overvoltage in the fuel cell stack as deterioration of the catalytic metal and estimating the degree of diffusion overvoltage as deterioration of the catalyst carrier based on the characteristics of the measured AC impedance, and determining the progress of deterioration of the catalytic metal and the catalyst carrier based on previously stored reference values of activation overvoltage and diffusion overvoltage for the vehicle traveling distance.
- the computer program realizing each function of the control device 100 including the deterioration determination device 10, in addition to the above algorithm, may execute the following when it is determined that the deterioration progresses quickly on the activation overvoltage side: suppressing the upper limit voltage value of the fuel cell vehicle in accordance with the deterioration on the activation voltage side.
- the computer program realizing each function of the control device 100 including the deterioration determination device 10, in addition to the above algorithm, may execute at least one of the following when it is determined that the deterioration progresses quickly on the diffusion overvoltage side: ( ⁇ ) reducing the rate of change of voltage per unit time during acceleration/deceleration operation of the fuel cell vehicle; and ( ⁇ ) delaying the timing of introducing air into the cathode electrode when starting up the fuel cell compared to normal.
- Such a computer program may be stored, for example, on a publicly known recording medium as described above, or may be downloaded to the fuel cell vehicle FCV from a publicly known server such as the cloud.
- the deterioration determination device for a fuel cell according to the second embodiment will be described below with reference to Figures 13 and 14.
- a Nyquist diagram was generated from the measured AC impedance to determine the deterioration progress of the catalyst metal and catalyst support, respectively.
- the deterioration determination device of the second embodiment is mainly characterized in that it does not require the generation of a Nyquist diagram, and determines the deterioration progress of the catalyst metal and catalyst support, respectively, based on multiple measurement points obtained from the AC impedance.
- the control device 100 extracts a plurality of measurement points based on the measured AC impedance in step 2A. More specifically, as shown in Fig. 13, the deterioration determination unit 10D extracts a plurality of measurement points in each of the high frequency side region and the low frequency side region based on the measured AC impedance.
- the boundary between the high frequency side region and the low frequency side region can be set, for example, at the central inflection point K (the inflection point sandwiched between the inflection point in the high frequency side region and the inflection point in the low frequency side region; see Fig. 13) when the Nyquist diagram is generated.
- FIG. 13 in this embodiment, three and two measurement points are extracted in the high frequency side region and the low frequency side region, respectively.
- the present invention is not limited to this embodiment, and any number of measurement points may be extracted in the high frequency side region and the low frequency side region as long as the number of measurement points does not reach a range that requires the generation of a Nyquist diagram.
- a diagram in which measurement points are extracted to the extent that a Nyquist diagram cannot be generated based on the measured AC impedance is referred to as a "catalyst deterioration determination diagram.”
- step 2A the control device 100 determines the degree of deterioration of the catalyst metal and catalyst carrier based on the reference values of the activation overvoltage and diffusion overvoltage for the vehicle mileage previously stored in steps 2A and 3A, respectively, using a method similar to that of the first embodiment described above.
- the control device 100 calculates the arc radius by applying the above-mentioned known approximation method based on the position of this increased high frequency side plot. Thereafter, as in the first embodiment, the control device 100 compares the calculated high frequency side arc radius with the reference value of the activation overvoltage (high frequency semicircle diameter) for the vehicle travel distance, and calculates the degree to which the calculated high frequency side arc radius differs from the reference value.
- FIG. 14 shows an example in which the high frequency side plot (measurement point) has changed in the catalyst deterioration determination diagram, but the degree of deterioration of the catalyst carrier can be determined in a similar manner when the low frequency side plot has changed. That is, the control device 100 compares the calculated low frequency side arc radius with a reference value of the diffusion overvoltage (low frequency semicircle diameter) for the vehicle travel distance, and calculates the degree to which the calculated low frequency side arc radius differs from the reference value.
- the diffusion overvoltage low frequency semicircle diameter
- the central inflection point K is used as the boundary, and the displacement of the measurement points belonging to the region on the higher frequency side of the central inflection point K is used to estimate the deterioration degree of the catalyst metal, while the displacement of the measurement points belonging to the region on the lower frequency side of the central inflection point K is used to estimate the deterioration degree of the catalyst support.
- control device 100 and fuel cell vehicle FCV including the deterioration determination device 10 according to the second embodiment although the accuracy of approximation of the arc radius is slightly reduced, it is possible to clearly distinguish between deterioration of the catalyst metal and the catalyst carrier in the same manner as in the first embodiment described above while reducing the computational load on the control device.
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Abstract
Description
すなわち燃料電池の電極では、酸化還元を繰り返す電圧の反復で径の小さな触媒金属の溶解が起きることが判明した。このとき溶解した金属の一部は、径の大きな金属粒子上に再堆積し得る。このような事象の発生は、特に車両を駆動する際の上限電圧値による影響が大きく寄与している。
他方、例えば車両が通常の加減速をするような電圧の反復が起きる場合には、電圧の走査速度が速いと比較的低い電圧でも触媒担体の腐食が進行することが判明した。
これらの劣化は共に燃料電池の性能低下に影響するが、いずれの劣化が進行しているか適切に判定することは、燃料電池から適切な電気エネルギーを継続して得るためには非常に重要な要素となり得る。
<燃料電池車FCV>
図1及び図2は、本実施形態に係る燃料電池スタックFCを備えた燃料電池車FCVの構成例と機能ブロックをそれぞれ示す模式図である。この燃料電池車FCVは、図2に示すように、車両の駆動トルクを生成する駆動力源21から出力される駆動トルクを左前輪3LF、右前輪3RF、左後輪3LR及び右後輪3RR(以下、特に区別を要しない場合には「車輪3」と総称する)に伝達する四輪駆動車として構成されている。駆動力源21は、本実施形態では前輪側に配置された公知の電動モータが例示できる。
次に図3を用いて、本実施形態における燃料電池スタックFCのうち触媒の劣化を判定可能な劣化判定装置10について説明する。すなわち本実施形態の劣化判定装置10は、燃料電池スタックFCにおける触媒金属および当該触媒金属を担持する触媒担体を含む触媒の劣化を判定する機能を有して構成されている。
次いで劣化判定部10Dは、算出したナイキスト線図における高周波側の円弧半径Rhを活性化過電圧の度合い、ナイキスト線図における低周波側の円弧半径Rlを拡散過電圧の度合いとしてそれぞれ規定する。換言すれば、本実施形態の劣化判定部10Dは、燃料電池スタックFCにおける活性化過電圧の度合いを触媒金属の劣化度合いと推定すると共に、拡散過電圧の度合いを触媒担体の劣化度合いと推定する。
そして劣化判定部10Dは、上記で算出した低周波側の円弧半径と、図8に例示した車両走行距離に対する拡散過電圧(低周波半円径)の基準値と、を比較し、算出した低周波側の円弧半径が基準値に対して差異がどの程度あるかを算出する。例えば燃料電池車FCVの走行距離が1700km時点において上記した劣化判定を実行した場合には、基準値b4と低周波側の円弧半径とを比較する。
次に図4も参照しつつ、本実施形態における劣化判定装置10を含む制御装置100によって実行可能な、触媒金属及び触媒担体の劣化抑制方法について説明する。なお、当該劣化抑制方法は、コンピュータが読み取り可能なプログラムのアルゴリズムとして用いられてもよい。かようなアルゴリズムを有するプログラムは、例えば公知のネットワークを介して燃料電池車FCVにダウンロード可能に流通したり、記録媒体に格納された形で流通し得る。
以下では、例えばユーザが燃料電池車FCVのシステムを起動して走行を開始したときを例にして説明する。
なお上記した劣化判定装置10の各機能を実現するコンピュータプログラムは、燃料電池スタックにおける触媒金属および当該触媒金属を担持する触媒担体を含む触媒の劣化を判定する燃料電池の劣化判定装置に適用されるコンピュータプログラムであって、一つ又は複数のプロセッサに、前記燃料電池スタックに交流信号を印加して前記燃料電池スタックの交流インピーダンスを計測すること、および、計測した前記交流インピーダンスの特性に基づいて前記燃料電池スタックにおける活性化過電圧の度合いを触媒金属の劣化と推定すると共に拡散過電圧の度合いを触媒担体の劣化と推定し、予め保持した車両走行距離に対する活性化過電圧及び拡散過電圧の基準値に基づいて前記触媒金属と前記触媒担体の劣化進度を判定すること、を含む処理を実行させ得る。
以下、図13及び図14を用いて第2実施形態に係る燃料電池の劣化判定装置について説明する。上述した第1実施形態においては、測定した交流インピーダンスからナイキスト線図を生成して触媒金属と触媒担体の劣化進度をそれぞれ判定していた。これに対して第2実施形態の劣化判定装置では、ナイキスト線図を生成することまでは要せず、交流インピーダンスから得られる複数の測定点に基づいて触媒金属と触媒担体の劣化進度をそれぞれ判定する点に主とした特徴がある。
より具体的には図13に示すように、劣化判定部10Dは、計測した交流インピーダンスに基づいて、高周波側領域と低周波側領域でそれぞれ複数の計測点を抽出する。なお高周波側領域と低周波側領域との境界は、例えばナイキスト線図が生成された際の中央変極点K(高周波側領域の変極点と低周波側領域の変極点とで挟まれた変極点。図13参照)を設定することができる。
この図13に示すように、測定した交流インピーダンスに基づいてナイキスト線図を生成するには至らない程度に計測点が抽出された図を、本実施形態では「触媒劣化判定図」と称する。
20 車両駆動制御装置
30 駆動制御部
40 提示制御部
FC 燃料電池スタック
FCV 燃料電池車
Claims (4)
- 燃料電池スタックにおける触媒金属および当該触媒金属を担持する触媒担体を含む触媒の劣化を判定する燃料電池の劣化判定装置であって、
前記燃料電池スタックに交流信号を印加して前記燃料電池スタックの交流インピーダンスを計測するインピーダンス計測部と、
計測した前記交流インピーダンスの特性に基づいて前記燃料電池スタックにおける活性化過電圧の度合いを触媒金属の劣化と推定すると共に拡散過電圧の度合いを触媒担体の劣化と推定し、予め保持した車両走行距離に対する活性化過電圧及び拡散過電圧の基準値に基づいて前記触媒金属と前記触媒担体の劣化進度を判定する劣化判定部と、
を含む、燃料電池の劣化判定装置。 - 前記劣化判定部は、
前記交流インピーダンスに基づいてナイキスト線図を算出し、
算出した前記ナイキスト線図における高周波側の円弧半径を活性化過電圧の度合いとし、前記ナイキスト線図における低周波側の円弧半径を拡散過電圧の度合いとして、
前記触媒金属と前記触媒担体の劣化進度を判定する、
請求項1に記載の燃料電池の劣化判定装置。 - 請求項1又は2に記載の劣化判定装置と、
前記劣化判定装置と電気的に接続された燃料電池と、
前記燃料電池の駆動を制御する制御装置と、を備えた燃料電池車であって、
前記制御装置は、
前記活性化過電圧側で劣化進度が早いと判定された場合に、活性化電圧側での劣化に応じて前記燃料電池車の上限電圧値を抑制する、
燃料電池車。 - 前記制御装置は、
前記拡散過電圧側で劣化進度が早いと判定された場合に、
(α)前記燃料電池車における加減速運転での単位時間に対する電圧の変化速度を下げることと、(β)前記燃料電池の起動時にカソード極に対して空気を導入するタイミングを通常時よりも遅らせること、の少なくとも1つを実行する、
請求項3に記載の燃料電池車。
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| US18/708,371 US20250015322A1 (en) | 2022-09-27 | 2022-09-27 | Fuel cell deterioration determination device and fuel cell vehicle |
| JP2024548859A JP7629147B2 (ja) | 2022-09-27 | 2022-09-27 | 燃料電池の劣化判定装置および燃料電池車 |
| PCT/JP2022/035874 WO2024069735A1 (ja) | 2022-09-27 | 2022-09-27 | 燃料電池の劣化判定装置および燃料電池車 |
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| JP2008282682A (ja) * | 2007-05-10 | 2008-11-20 | Toyota Motor Corp | 燃料電池システム |
| JP2012089448A (ja) * | 2010-10-22 | 2012-05-10 | Toyota Motor Corp | 燃料電池の劣化判定システム |
| US20170170500A1 (en) * | 2015-12-09 | 2017-06-15 | Hyundai Motor Company | Method and system for diagnosing state of fuel cell stack |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2008282682A (ja) * | 2007-05-10 | 2008-11-20 | Toyota Motor Corp | 燃料電池システム |
| JP2012089448A (ja) * | 2010-10-22 | 2012-05-10 | Toyota Motor Corp | 燃料電池の劣化判定システム |
| US20170170500A1 (en) * | 2015-12-09 | 2017-06-15 | Hyundai Motor Company | Method and system for diagnosing state of fuel cell stack |
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