An Adaptive Oxygen Excess Ratio Setting Method for a Hydrogen Fuel Cell System

Abstract

The present invention discloses a method for adaptively setting the oxygen excess ratio of a hydrogen fuel cell system. The method includes: firstly, off-line measuring the curve of the economically optimal oxygen excess ratio of a brand-new fuel cell system and the polarization curve of a single fuel cell at aging stage k, and identifying the parameters of the electrochemical surface area, ohmic resistance and limiting current density of the fuel cell; then, calculating in real time the total voltage drop during the purge interval of the fuel cell and the voltage drop caused by the decrease in the electrochemical surface area, and further calculating in real time the voltage drop caused by the accumulation of the anode nitrogen concentration, so as to calculate the voltage drop caused by the obstruction of the cathode oxygen transmission; furthermore, calculating the pressure that needs to be increased at the cathode; finally, determining the cathode adaptive oxygen excess ratio of the fuel cell at aging stage k; when the fuel cell enters a new aging stage, resetting the adaptive oxygen excess ratio for the fuel cell in the new aging stage. The present invention improves the stability, durability, reliability and safety of the fuel cell operation.

Description

Technical Field

[0001] The present invention belongs to the field of fuel cell system applications, and relates to a method for setting the cathode oxygen excess ratio of a proton exchange membrane fuel cell, and an adaptive oxygen excess ratio setting method for a hydrogen fuel cell system considering durability and reliability. Background Art

[0002] The setting of the cathode oxygen excess ratio of a proton exchange membrane fuel cell system affects its economy, durability and reliability. When the oxygen excess ratio is too low, the water generated at the cathode cannot be taken away in time, which affects the mass transfer of gas in the membrane electrode at the diffusion layer, and even causes local hot spots to burn the membrane electrode, thus affecting the durability and reliability of the system. To avoid the above problems, a relatively high oxygen excess ratio is usually maintained at the cathode. However, too high an oxygen excess ratio means an increase in the energy consumption of the air compressor, thus consuming more parasitic power and reducing the economy of the system. Therefore, it is necessary to set an appropriate oxygen excess ratio to avoid both oxygen starvation and energy waste.

[0003] At present, there are two most commonly used methods for setting the oxygen excess ratio in actual proton exchange membrane fuel cell systems. One is to directly set it to a fixed value of 2. Existing research has shown that when the oxygen excess ratio is controlled near 2, the fuel cell stack will not experience oxygen starvation and performance degradation under most operating conditions where the load current does not change rapidly. Although this method is simple, it does not consider the influence of the oxygen excess ratio on more dimensions of the system performance, such as economy, durability and reliability. Another method is the oxygen excess ratio with optimal economy. Generally, through system calibration, the oxygen excess ratio corresponding to the maximum net output power of the system under different load conditions is determined as the oxygen excess ratio with optimal economy. Although this method ensures the optimal economy of the system, it does not consider the influence of the oxygen excess ratio on the stability, durability and reliability of the system, as well as the fault tolerance function of the oxygen excess ratio. Therefore, an oxygen excess ratio adaptive setting method that can consider the influence of more dimensions of system performance needs to be further studied and optimized. Summary of the Invention

[0004] To address the deficiencies of the prior art, the present invention proposes a method for adaptively setting the oxygen excess ratio in a hydrogen fuel cell system. On the basis of the existing economically optimal oxygen excess ratio, the present invention further considers the effects of fuel cell durability and reliability. First, this method offsets the voltage drop caused by the decrease in the electrochemical surface area during the fuel cell aging process by adaptively increasing the oxygen excess ratio, improving the stability of the output of the fuel cell system; then, by adaptively increasing or decreasing the oxygen excess ratio, the fault tolerance for fuel cell flooding and drying faults is achieved, improving the reliability and durability of the fuel cell system. In addition, this method can also adaptively handle the shift of the optimal oxygen excess ratio caused by the decrease in the efficiency of the air compressor after aging, realizing the stability of the output performance of the fuel cell system throughout its life cycle.

[0005] The solution adopted by the present invention is as follows:

[0006] 1) Offline measure the optimal oxygen excess ratio curve of a brand-new proton exchange membrane fuel cell system;

[0007] 2) Offline measure the polarization curve of the proton exchange membrane fuel cell at aging stage k. Based on the fuel cell voltage model, use the polarization curve piecewise identification method to fit the polarization curve at aging stage k, and estimate and obtain the electrochemical surface area ECSA, ohmic resistance R ohmic and limiting current density i lim ;

[0008] 3) Online monitor the voltage and current during the operation of the fuel cell, and based on the electrochemical surface area ECSA, ohmic resistance R ohmic and limiting current density i lim of the fuel cell at aging stage k, as well as the optimal oxygen excess ratio curve, and calculate the total voltage drop ΔV cell during the purge interval of the fuel cell in real time, and the voltage drop ΔV ECSA caused by the decrease in the electrochemical surface area ECSA. Then, according to the anode nitrogen concentration observer, calculate the voltage drop ΔV N2，an caused by the accumulation of anode nitrogen concentration in real time. By subtracting the voltage drop ΔV cell caused by the decrease in the electrochemical surface area ECSA and the voltage drop ΔV ECSA caused by the accumulation of anode nitrogen concentration from the total voltage drop ΔV N2，an during the purge interval of the fuel cell, calculate and obtain the voltage drop ΔV w caused by the obstruction of cathode oxygen transport;

[0009] 4) Calculate the additional pressure ΔP ECSA required for the cathode according to the voltage drop ΔV w caused by the decrease in the electrochemical surface area ECSA and the voltage drop ΔV O2，c;

[0010] 5) Determine the adaptive oxygen excess ratio λ of the fuel cell at aging stage k based on the additional pressure ΔP required at the cathode O2，c , and determine the adaptive oxygen excess ratio λ of the fuel cell at aging stage k O2，k ;

[0011] 6) When the operating time of the fuel cell does not exceed the preset aging duration, repeat steps 3)-5); when the operating time of the fuel cell exceeds the preset aging duration, the fuel cell enters a new aging stage, then determine whether the fuel cell has reached its maximum service life. If so, end; if not, repeat steps 2)-5) and set a new adaptive oxygen excess ratio for the fuel cell in the new aging stage.

[0012] In step 2), the fuel cell voltage model is:

[0013] E cell = E ner - η act+cross - η ohmic - η con

[0014] where E cell represents the voltage of a single fuel cell, E ner represents the Nernst voltage of a single fuel cell, η act+cross represents the sum of the activation loss and permeation loss of a single fuel cell, η ohmic represents the total ohmic loss of a single fuel cell, η con represents the total concentration loss of a single fuel cell;

[0015] The sum of the activation loss and permeation loss η of a single fuel cell act+cross is set by the following formula:

[0016]

[0017]

[0018] where A represents the activation constant of the cathode, i cross represents the permeation current density, i represents the fuel cell load current density, the constant 10 is a unit conversion factor, f represents the catalyst roughness factor, and f = ECSA × L pt , ECSA is the electrochemically active surface area of the platinum catalyst, L pt represents the platinum loading of the cathode, i 0，c represents the cathode exchange current density, represents the reference partial pressure of oxygen at the cathode under standard operating conditions, T ref represents the reference operating temperature of the fuel cell, represents at and T ref Reference value of the cathode exchange current density under operating conditions Denotes the partial pressure of oxygen at the cathode, γ c Denotes the reaction order of the oxygen reduction reaction, E act,c Denotes the activation energy of the oxygen reduction reaction, R denotes the ideal gas constant, and T denotes the operating temperature of the fuel cell;

[0019] The total ohmic loss η of the single fuel cell ohmic Is calculated by the following formula:

[0020] η ohmic = iR ohmic

[0021]

[0022] Wherein, R ohmic Denotes the total ohmic resistance, R m Denotes the proton transfer resistance of the proton exchange membrane Denotes the effective proton transfer resistance of the cathode catalyst layer, R ct Denotes the contact resistance between the bipolar plate and the gas diffusion layer;

[0023] The total concentration loss η of the single fuel cell con Is set by the following formula:

[0024]

[0025] Wherein, B c Denotes the concentration constant of the cathode, i lim Denotes the limiting current density.

[0026] In the step 3), the total voltage drop ΔV of the single fuel cell cell The calculation formula is as follows:

[0027] ΔV cell = V cell，0 - V cell

[0028] Wherein, V cell，0 Denotes the single-cell voltage of a brand-new fuel cell, V cell Denotes the single-cell voltage of the fuel cell during actual operation;

[0029] In the single fuel cell, the voltage drop ΔV caused by the decrease in the electrochemically active surface area ECSA ECSA The calculation formula is as follows:

[0030]

[0031] Among them, A represents the activation constant of the cathode, ECSA0 represents the electrochemical surface area of a brand-new fuel cell, and ECSA k represents the electrochemical surface area of the fuel cell at aging stage k; i cross represents the permeation current density, i represents the load current density of the fuel cell, the constant 10 is a unit conversion factor, and L pt represents the platinum loading of the cathode, and i 0，c represents the cathode exchange current density;

[0032] In a single fuel cell, the voltage drop ΔV caused by the accumulation of nitrogen concentration at the anode N2,an is calculated as follows:

[0033]

[0034] Among them, p an represents the total pressure of the anode gas, p N2,an represents the partial pressure of nitrogen at the anode, R represents the ideal gas constant; T represents the operating temperature of the fuel cell; F is the Faraday constant;

[0035] In a single fuel cell, the voltage drop ΔV caused by the obstruction of oxygen transport at the cathode w is calculated as follows:

[0036] ΔV w =ΔV cell -ΔV ECSA -ΔV N2,an .

[0037] In step 4), the additional pressure ΔP required at the cathode O2，c is calculated as follows:

[0038]

[0039]

[0040]

[0041]

[0042]

[0043] ΔV ECSA +ΔV w =ΔE ner +Δη act+cross +Δη con

[0044] Among them, P O2，c represents the partial pressure of oxygen at the cathode, and ΔE ner represents ΔPO2，c The change value of the Nernst voltage of a single fuel cell caused, Δη act+cross Denotes ΔP O2，c The change value of the sum of the activation loss and the permeation loss of a single fuel cell caused, Δη con Denotes ΔP O2，c The change value of the total concentration loss of a single fuel cell caused, R represents the ideal gas constant; T represents the operating temperature of the fuel cell; F is the Faraday constant; A represents the activation constant of the cathode, i 0，c Denotes the cathode exchange current density; Δi 0，c Denotes ΔP O2，c The change value of the cathode exchange current density caused, Denotes the reference partial pressure of cathode oxygen under standard operating conditions, T ref Denotes the reference operating temperature of the fuel cell, Denotes at And T ref The reference value of the cathode exchange current density under the operating conditions; E act，c Denotes the activation energy of the oxygen reduction reaction; B c Denotes the concentration constant of the cathode, i lim Denotes the limiting current density; i denotes the load current density of the fuel cell, Δi lim Denotes ΔP O2，c The change value of the limiting current density caused, n e，c Denotes the number of electrons in the cathode redox reaction, Denotes the effective diffusion coefficient of cathode oxygen, L c Denotes the thickness of the cathode catalyst layer, x O2，ch Denotes the mass fraction of oxygen in the cathode flow channel.

[0045] In the said step 5), the cathode self-adaptive oxygen excess ratio λ of the fuel cell at the aging stage k O2，k The calculation formula is:

[0046]

[0047]

[0048] Wherein, P sm Denotes the air pressure in the supply manifold, P out Denotes the pressure at the cathode outlet of the fuel cell, I denotes the load current of the fuel cell, c1 and c2 are the first and second simplification coefficients P O2，c Denotes the partial pressure of oxygen in the cathode.

[0049] The beneficial effects of the present invention are:

[0050] Based on the existing economically optimal oxygen excess ratio, the present invention further considers the influence of the oxygen excess ratio on the durability and reliability of the fuel cell. By adaptively increasing the oxygen excess ratio, the voltage drops caused by the decrease in the electrochemically active surface area during the fuel cell aging process and the voltage drop caused by the accumulation of liquid water during operation are offset, improving the stability of the output of the fuel cell system. By adaptively increasing or decreasing the oxygen excess ratio, the fault tolerance ability for fuel cell flooding and drying faults is achieved, enhancing the reliability and durability of the fuel cell system. In addition, this method can also adaptively handle the shift of the optimal excess ratio caused by the decrease in the efficiency of the air compressor after aging, improving the stability of the output performance of the fuel cell system throughout its life cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is the overall flowchart of the present invention.

[0052] Figure 2 is the structural diagram of the fuel cell cathode intake system in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0054] As Figure 1 shown, the present invention includes the following steps:

[0055] 1) Offline measure the optimal oxygen excess ratio curve of a brand-new proton exchange membrane fuel cell system.

[0056] The structure of the fuel cell cathode intake system used in the embodiment is as Figure 2 shown. The oxygen excess ratio is defined as the ratio of the amount of oxygen supplied to the fuel cell system to the amount of oxygen consumed by the system:

[0057]

[0058]

[0059]

[0060] where, W O2，in and W O2，rct respectively represent the oxygen flow rate entering the stack and the oxygen consumption in the electrochemical reaction, c1 and c2 are the first and second simplification coefficients respectively, both of which are constant values. P sm represents the air pressure in the supply manifold, P c represents the average pressure of the fuel cell cathode, P out represents the pressure at the outlet of the fuel cell cathode, I represents the load current of the fuel cell, k sm，out represents the supply manifold outlet hole constant, x O2，atmRepresents the oxygen mass fraction, ω atm Represents the relative humidity of the air, n is the number of single cells in the fuel cell stack, M O2 Is the molar mass of oxygen, F is the Faraday constant.

[0061] The energy output by the fuel cell stack is:

[0062] P out = nV cell I

[0063] Among them, V cell Is the average voltage of each single cell, n is the number of fuel cell plates in the stack.

[0064] The parasitic power consumed by the air compressor is calculated as follows:

[0065]

[0066] Among them, C p Represents the specific heat capacity of the air, T atm Is the temperature of the oxygen, r represents the heat capacity ratio of the air, η cp Is the efficiency of the oxygen compressor, W cp Represents the air flow rate at the outlet of the air compressor.

[0067] When the actual fuel cell system is operating, compared with the power consumed by the air compressor, the power consumed by other components is relatively small and can be ignored. Therefore, the net output power of the system can be approximately calculated as:

[0068] P net = P out - P cp

[0069] The measurement of the optimal excess ratio curve is to find an optimal oxygen excess ratio at different load currents, so as to maximize the net output power of the fuel cell system.

[0070] 2) Offline measure the polarization curve of the proton exchange membrane fuel cell at the aging stage k. Based on the fuel cell voltage model, use the polarization curve piecewise identification method to fit the polarization curve at the aging stage k, and estimate and obtain the electrochemical surface area ECSA, ohmic resistance R ohmic And the limiting current density i lim ;

[0071] In specific implementation, the measurement method of the polarization curve is as follows: 1) Adjust the output current of the fuel cell to the maximum current density and keep the parameters of the stack operation stable; 2) Open the purge solenoid valve at the outlet of the anode circuit of the fuel cell for 2 s, discharge all the nitrogen in the anode of the stack, and then close the solenoid valve; 3) Measure the voltage value of the fuel cell as the voltage value corresponding to this current density on the polarization curve; 4) Adjust the output current of the fuel cell to the next current density, and repeat steps 2)-3) until the current density reaches the minimum current density value of the fuel cell; 5) Fit the voltage values corresponding to different current densities to obtain the polarization curve of the fuel cell.

[0072] In step 2), the voltage model of the proton exchange membrane fuel cell is:

[0073] E cell = E ner - η act+cross - η ohmic - η con

[0074] Among them, E cell represents the voltage of a single fuel cell, E ner represents the Nernst voltage of a single fuel cell, η act+cross represents the sum of the activation loss and the permeation loss of a single fuel cell, η ohmic represents the total ohmic loss of a single fuel cell, η con represents the total concentration loss of a single fuel cell.

[0075] The sum of the activation loss and the permeation loss of a single fuel cell, η act+cross is set by the following formula:

[0076]

[0077]

[0078] Among them, A represents the activation constant of the cathode, i cross represents the permeation current density, i represents the fuel cell load current density, the constant 10 is the unit conversion factor, f represents the catalyst roughness factor, and f = ECSA × L pt , ECSA is the electrochemically active surface area of the platinum catalyst, L pt represents the platinum loading of the cathode, i 0，c represents the cathode exchange current density, represents the reference partial pressure of cathode oxygen under standard operating conditions, T ref represents the reference operating temperature of the fuel cell, represents at and T ref the reference value of the cathode exchange current density under the operating conditions represents the partial oxygen pressure of the cathode, γ c represents the reaction order of the oxygen reduction reaction, E act,c represents the activation energy of the oxygen reduction reaction, R represents the ideal gas constant, and T represents the operating temperature of the fuel cell.

[0079] The total ohmic loss η of a single fuel cell ohmic is calculated by the following formula:

[0080] η ohmic = iR ohmic

[0081]

[0082] where, R ohmic represents the total ohmic resistance, R m represents the proton transport resistance of the proton exchange membrane, represents the effective proton transport resistance of the cathode catalyst layer, R ct represents the contact resistance between the bipolar plate and the gas diffusion layer.

[0083] The total concentration loss η of a single fuel cell con is set by the following formula:

[0084]

[0085] where, B c represents the concentration constant of the cathode, i lim represents the limiting current density.

[0086] The polarization curve is divided into three segments according to different dominant losses by using the polarization curve piecewise identification method, namely, the part dominated by activation loss in the low current density range, the part dominated by ohmic loss in the medium and high current density ranges, and the part dominated by concentration loss in the high current density range. The three segments of the polarization curve are respectively identified by the least square fitting algorithm, and the electrochemically active surface area ECSA, the ohmic resistance R ohmic and the limiting current density i lim are obtained.

[0087] 3) Online monitor the voltage and current during the operation of the fuel cell, and based on the electrochemically active surface area ECSA, the ohmic resistance R ohmic and the limiting current density i lim of the fuel cell at the aging stage k, as well as the optimal oxygen excess ratio curve, calculate the total voltage drop ΔV cell during the purge interval of the fuel cell and the voltage drop ΔV ECSA caused by the decrease of the electrochemically active surface area ECSA in real time, and then calculate the voltage drop ΔV caused by the accumulation of anode nitrogen concentration according to the anode nitrogen concentration observer in real timeN2，an During the purge interval, the total voltage drop ΔV of the fuel cell cell subtracts the voltage drop ΔV caused by the decrease in the electrochemically active surface area (ECSA), ECSA and the voltage drop ΔV caused by the accumulation of nitrogen concentration at the anode, N2，an and then calculates the voltage drop ΔV caused by the hindered oxygen transport at the cathode; w ;

[0088] In step 3), the total voltage drop ΔV of a single fuel cell cell is calculated according to the following formula:

[0089] ΔV cell = V cell，0 - V cell

[0090] where V cell，0 represents the voltage of a single cell of a brand-new fuel cell, and V cell represents the voltage of a single cell of the fuel cell during actual operation;

[0091] In a single fuel cell, the voltage drop ΔV caused by the decrease in the electrochemically active surface area (ECSA) ECSA is calculated according to the following formula:

[0092]

[0093] where ECSA0 represents the electrochemically active surface area of a brand-new fuel cell, and ECSA k represents the electrochemically active surface area of the fuel cell at aging stage k; i 0，c represents the cathodic exchange current density;

[0094] In a single fuel cell, the voltage drop ΔV caused by the accumulation of nitrogen concentration at the anode N2，an is calculated according to the following formula:

[0095]

[0096] where p an represents the total pressure of the anode gas, and p N2，an represents the partial pressure of nitrogen at the anode;

[0097] The voltage drop ΔV caused by the hindered oxygen transport at the cathode w is calculated according to the following formula:

[0098] ΔV w = ΔV cell - ΔV ECSA - ΔV N2，an

[0099] 4) According to the voltage drop ΔV caused by the decrease in the electrochemically active surface area (ECSA)ECSA and the voltage drop ΔV caused by the hindered oxygen transport at the cathode w Calculate the additional pressure ΔP required at the cathode O2，c ;

[0100] Increasing the cathode pressure in a fuel cell leads to changes in the loss voltage, including E ner , η act+cross and η con changes,

[0101]

[0102]

[0103]

[0104]

[0105]

[0106] In step 4), the additional pressure ΔP required at the cathode O2，c is calculated as follows:

[0107] ΔV ECSA +ΔV w =ΔE ner +Δη act+cross +Δη con

[0108] where P O2，c represents the partial pressure of oxygen at the cathode, ΔE ner represents the change in the Nernst voltage of a single fuel cell caused by ΔP O2，c , Δη act+cross represents the change in the sum of the activation loss and the permeation loss of a single fuel cell caused by ΔP O2，c , Δη con represents the change in the total concentration loss of a single fuel cell caused by ΔP O2，c , Δi 0，c represents the change in the cathodic exchange current density caused by ΔP O2，c , E act，c represents the activation energy of the oxygen reduction reaction, Δi lim represents the change in the limiting current density caused by ΔP O2，c , n e，c represents the number of electrons in the cathodic redox reaction, represents the effective diffusion coefficient of oxygen at the cathode, L c represents the thickness of the cathode catalyst layer x O2，ch represents the mass fraction of oxygen in the cathode flow channel.

[0109] 5) Based on the additional pressure ΔP required for the cathode O2，c , determine the adaptive oxygen excess ratio λ of the fuel cell at aging stage k O2，k .

[0110] In step 5), the adaptive oxygen excess ratio λ of the cathode of the fuel cell at aging stage k O2，k is calculated by the formula:

[0111]

[0112]

[0113] 6) When the operating time of the fuel cell does not exceed the preset aging duration, repeat steps 3)-5); when the operating time of the fuel cell exceeds the preset aging duration, the fuel cell enters a new aging stage, then determine whether the fuel cell has reached its maximum service life. If so, end; if not, repeat steps 2)-5) and set a new adaptive oxygen excess ratio for the fuel cell in the new aging stage.

Claims

1. A method for adaptively setting the oxygen excess ratio of a hydrogen fuel cell system, characterized in that, Including the following steps: 1) Offline measurement of the optimal oxygen excess ratio curve of a brand-new proton exchange membrane fuel cell system; 2) Offline measurement of the polarization curve of the proton exchange membrane fuel cell at aging stage k. Based on the fuel cell voltage model, the polarization curve at aging stage k is fitted using the piecewise identification method of the polarization curve, and the electrochemically active surface area ECSA and the ohmic resistance R ohmic and the limiting current density i lim ; 3) Online monitor the voltage and current during the operation of the fuel cell, and based on the electrochemically active surface area ECSA, ohmic resistance R of the fuel cell at aging stage k ohmic and the limiting current density i lim as well as the optimal oxygen excess ratio curve, calculate in real time the total voltage drop ΔV of the fuel cell during the purge interval cell and the voltage drop ΔV caused by the decrease in the electrochemically active surface area ECSA ECSA , and then calculate in real time the voltage drop ΔV caused by the accumulation of anode nitrogen concentration according to the anode nitrogen concentration observer N2,an , through the total voltage drop ΔV of the fuel cell during the purge interval cell subtract the voltage drop ΔV caused by the decrease in the electrochemically active surface area ECSA ECSA and the voltage drop ΔV caused by the accumulation of anode nitrogen concentration N2,an to calculate and obtain the voltage drop ΔV caused by the obstruction of cathode oxygen transport w ; 4) Calculate the increased partial oxygen pressure ΔP required for the cathode based on the voltage drop ΔV caused by the decrease in the electrochemically active surface area (ECSA). ECSA and the voltage drop ΔV caused by the hindered oxygen transport at the cathode w Calculate the increased partial oxygen pressure ΔP required for the cathode O2,c ; 5) Determine the adaptive oxygen excess ratio λ of the fuel cell at aging stage k based on the increased oxygen partial pressure ΔP required by the cathode O2,c ; O2,k ; 6) When the fuel cell operation time does not exceed the preset aging duration, repeat steps 3)-5); when the fuel cell operation time exceeds the preset aging duration, the fuel cell enters a new aging stage, then determine whether the fuel cell has reached the maximum service life. If so, end; if not, repeat steps 2)-5) and set a new adaptive oxygen excess ratio for the fuel cell in the new aging stage; In the step 4), the partial pressure of oxygen ΔP to be increased at the cathode O2,c is calculated as follows: ΔV ECSA +ΔV w =ΔE ner +Δη act+cross +Δη con Among them, P O2,c represents the partial oxygen pressure of the cathode, ΔE ner represents the change value of the Nernst voltage of a single fuel cell caused by ΔP O2,c Δη act+cross represents the change value of the sum of the activation loss and the permeation loss of a single fuel cell caused by ΔP O2,c Δη con represents the change value of the total concentration loss of a single fuel cell caused by ΔP, R represents the ideal gas constant; T represents the operating temperature of the fuel cell; F is the Faraday constant; A represents the activation constant of the cathode, i O2,c represents the cathode exchange current density; Δi 0,c represents the change value of the cathode exchange current density caused by ΔP 0,c O2,c O2,c represents the reference partial oxygen pressure of cathode oxygen under standard operating conditions, T represents the reference operating temperature of the fuel cell, ref represents at and T ref the reference value of the cathode exchange current density under the operating conditions; E act,c represents the activation energy of the oxygen reduction reaction; B c represents the concentration constant of the cathode, i lim represents the limiting current density; i represents the load current density of the fuel cell, Δi lim represents the change value of the limiting current density caused by ΔP O2,c n e,c represents the number of electrons in the cathode redox reaction, represents the effective diffusion coefficient of cathode oxygen, L c represents the thickness of the cathode catalyst layer, x O2,ch represents the mass fraction of oxygen in the cathode flow channel;​ In step 5), the cathode self-adaptive oxygen excess ratio λ of the fuel cell at aging stage k O2,k is calculated by the following formula: where, P sm represents the air pressure in the air supply manifold, P out represents the pressure at the cathode outlet of the fuel cell, I represents the load current of the fuel cell, c1 and c2 are the first and second simplification coefficients respectively, and P O2,c represents the oxygen partial pressure at the cathode.

2. The adaptive oxygen excess ratio setting method for a hydrogen fuel cell system according to claim 1, wherein In step 2), the fuel cell voltage model is: E cell = E ner - η act+cross - η ohmic - η con Among them, E cell represents the voltage of a single fuel cell, E ner represents the Nernst voltage of a single fuel cell, η act+cross represents the sum of the activation loss and the permeation loss of a single fuel cell, η ohmic represents the total ohmic loss of a single fuel cell, η con represents the total concentration loss of a single fuel cell; The sum η of the activation loss and the permeation loss of the single fuel cell act+cross is set by the following formula: Among them, A represents the activation constant of the cathode, i cross represents the permeation current density, i represents the fuel cell load current density, the constant 10 is a unit conversion factor, f represents the catalyst roughness factor, and f = ECSA × L pt , where ECSA is the electrochemically active surface area of the platinum catalyst, L pt represents the platinum loading of the cathode, i 0,c represents the cathode exchange current density, represents the reference partial pressure of oxygen at the cathode under standard operating conditions, T ref represents the reference operating temperature of the fuel cell, represents at and T ref the reference value of the cathode exchange current density under the operating conditions, γ c represents the reaction order of the oxygen reduction reaction, E act,c represents the activation energy of the oxygen reduction reaction, R represents the ideal gas constant, and T represents the operating temperature of the fuel cell; The total ohmic loss η of the single fuel cell ohmic is calculated by the following formula: η ohmic = iR ohmic Among them, R ohmic represents the total ohmic resistance, R m represents the proton transfer resistance of the proton exchange membrane, represents the effective proton transfer resistance of the cathode catalyst layer, R ct represents the contact resistance between the bipolar plate and the gas diffusion layer; The total concentration loss η of the single fuel cell con is set by the following formula: Among them, B c represents the concentration constant of the cathode, and i lim represents the limiting current density.

3. The adaptive oxygen excess ratio setting method for a hydrogen fuel cell system according to claim 1, characterized in that, In step 3), the total voltage drop ΔV of a single fuel cell cell is calculated as follows: ΔV cell = V cell,0 - V cell Among them, V cell,0 represents the single-cell voltage of a brand-new fuel cell, and V cell represents the single-cell voltage of the fuel cell during actual operation; In a single fuel cell, the voltage drop ΔV caused by the decrease in the electrochemically active surface area (ECSA) ECSA is calculated as follows: Wherein, A represents the activation constant of the cathode, ECSA0 represents the electrochemical surface area of a brand-new fuel cell, and ECSA k represents the electrochemical surface area of the fuel cell at aging stage k; i cross represents the permeation current density, i represents the load current density of the fuel cell, the constant 10 is a unit conversion factor, and L pt represents the platinum loading of the cathode, and i 0,c represents the cathode exchange current density; In a single fuel cell, the voltage drop ΔV caused by the accumulation of anode nitrogen concentration N2,an is calculated as follows: where p an represents the total pressure of the anode gas, and p N2,an represents the partial pressure of nitrogen in the anode. R represents the ideal gas constant; T represents the operating temperature of the fuel cell; F is the Faraday constant; In a single fuel cell, the voltage drop ΔV w caused by the hindered oxygen transport at the cathode is calculated as follows: ΔV w = ΔV cell -ΔV ECSA -ΔV N2,an 。

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