A method and device for diagnosing failure of a fuel cell stack

Abstract

The present invention provides a method and device for diagnosing failure of a fuel cell stack, which belongs to the field of fuel cell technology and solves the problem that the efficiency calculation accuracy of the existing stack is not high and the failure diagnosis can no longer be performed after the reaction efficiency is reduced. The method includes starting the fuel cell engine and determining that it is in a normal startup and operation state; controlling the stack to operate at the current of the set operating point, and obtaining the mass of oxygen entering the stack. m 1. Hydrogen quality m 2. Oxygen concentration of the mixed gas leaving the reactor c , Hydrogen concentration d , the theoretical output energy of the reaction gas consumption is obtained Q ; Get the actual output power of the battery stack Q 1 and heat production Q 0, combined with the above energy Q The stack efficiency or ; According to the above stack efficiency or Identify whether the stack has failed. This method can accurately calculate the efficiency of the stack in real time and diagnose the failure of the stack. When the stack fails, it will shut down the stack in time to avoid irreversible damage and effectively increase the service life of the stack.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell testing, and in particular to a method and device for diagnosing failure of a fuel cell stack. Background Art

[0002] After long-term operation, the performance of proton exchange membrane fuel cells will degrade, or single cells will fail under extreme loads. If the above failures are not identified in time and the fuel cell continues to operate, irreversible damage will be caused to the entire stack. Therefore, it is necessary to detect whether the stack has failed in real time to ensure the durability of the fuel cell.

[0003] The existing technology generally calculates the efficiency of the fuel cell stack through the polarization curve of the fuel cell stack, but the accuracy of the stack efficiency obtained by this method is not high. If the performance of the stack decays and the reaction efficiency decreases, the stack efficiency at the current moment cannot be identified, and the fault diagnosis of stack failure cannot be performed. Summary of the invention

[0004] In view of the above analysis, an embodiment of the present invention aims to provide a method and device for diagnosing failure of a fuel cell stack, so as to solve the problem that the efficiency calculation accuracy of the prior art stack is low and failure diagnosis can no longer be performed after the reaction efficiency is reduced.

[0005] On the one hand, an embodiment of the present invention provides a method for diagnosing a failure of a fuel cell stack, comprising the following steps:

[0006] Start the fuel cell engine and make sure it is in normal operation;

[0007] Control the stack to operate at the current of the set operating point, and obtain the oxygen mass entering the stack within the set period from the current moment m 1 , Hydrogen quality m 2 , oxygen concentration of the mixed gas leaving the reactor c , Hydrogen concentration d , and then the theoretical output energy of the reaction gas consumption is obtained Q ;

[0008] Get the actual output power of the battery stack Q 1 and heat production Q 0 , combined with the above energy Q The stack efficiency or ;

[0009] According to the above stack efficiency or Identify whether the battery stack has failed.

[0010] The beneficial effects of the above technical solution are as follows: It provides a method for accurately calculating the efficiency of the battery stack in real time. or A new method for diagnosing failure of battery stacks is also developed. This method can be used to diagnose failure of all current battery stacks. When the tested battery stack fails, the battery stack is shut down in time to avoid irreversible damage to the battery stack, effectively extending the service life of the battery stack.

[0011] Based on a further improvement of the above method, the step of starting the fuel cell engine and determining that it is in a normal startup and operation state further includes:

[0012] Starting the fuel cell engine;

[0013] Detect whether the hydrogen path of the fuel cell engine is faulty. If so, control the fuel cell engine to shut down and issue a hydrogen path fault warning. Otherwise, proceed to the next step.

[0014] Detect whether the air path of the fuel cell engine is faulty. If so, control the fuel cell engine to shut down and issue an air path fault warning. Otherwise, execute the next step.

[0015] Check whether the coolant circuit of the fuel cell engine is faulty. If so, control the fuel cell engine to shut down and issue a warning of the coolant circuit fault. Otherwise, make sure that the fuel cell engine is in a normal startup and operation state.

[0016] Furthermore, the step of controlling the battery stack to operate at a current of a set operating point further includes:

[0017] Obtain the amplitude of the output current of the battery stack at a set operating point;

[0018] Determine the theoretical speed of the air compressor and the theoretical duty cycle of the hydrogen injection device corresponding to the amplitude of the above current, control the air compressor to operate at the above theoretical speed, and control the hydrogen injection device to operate at the theoretical duty cycle to ensure that the fuel cell stack operates at the current of the set operating point.

[0019] Further, the mass of oxygen entering the reactor within the set period is obtained by the following steps: m 1 , Hydrogen quality m 2 :

[0020] Get the mass concentration of oxygen in the air at the current moment r 1 、 The volume of air entering the pile per unit time V 1 The oxygen mass entering the reactor during the set period is obtained by the following formula: m 1 ,

[0021] m 1 = r 1 V 1 ,

[0022] Get the mass concentration of hydrogen at the hydrogen supply end of the fuel cell engine at the current moment r 2 、 The volume of hydrogen entering the reactor per unit time V 2 The following formula is used to calculate the mass of hydrogen entering the reactor during the set period: m 2 ,

[0023] m 2 = r 2 V 2 .

[0024] Further, the oxygen concentration of the mixed gas leaving the reactor is obtained by the following steps: c , Hydrogen concentration d :

[0025] The oxygen concentration of the stack mixed gas is collected in real time through the oxygen concentration sensor installed in the tail exhaust pipe. c ;

[0026] The hydrogen concentration of the stack mixed gas is collected in real time through the hydrogen concentration sensor installed in the tail exhaust pipe. d .

[0027] Further, the theoretical output energy of the reaction consumption gas is obtained through the following steps: Q :

[0028] Get the volume of mixed gas discharged from the stack per unit time V , the mass of oxygen consumed by the reaction is obtained by the following formula ∆ 1 , Hydrogen mass ∆ 2

[0029] ∆ 1 = m 1 - CV ,

[0030] ∆ 2 = m 2 - dV ,

[0031] According to the oxygen mass consumed by the above reaction ∆ 1 , Hydrogen mass ∆2 , combined with the specific electrochemical reaction in the fuel cell stack, the theoretical output energy of the reaction consumption gas is obtained Q .

[0032] Further, the actual output power of the battery stack is obtained through the following steps: Q 1 and heat production Q 0 :

[0033] Get the real-time output voltage of the battery stack V , Current I ;

[0034] According to the above voltage V , Current I The actual output power of the battery stack is obtained by the following formula: Q 1 ,

[0035] ,

[0036] In the formula, t For time, T To set the time;

[0037] Get the set time T Internal coolant temperature rise ∆K The heat generation of the battery stack is obtained by the following formula: Q 0 ,

[0038] ,

[0039] In the formula, C 1 For the hot melt of the coolant, M 1 The quality of the coolant.

[0040] Further, the stack efficiency is obtained by the following formula: or ,

[0041] or =( Q 0 + Q 1 ) / Q .

[0042] Further, according to the above-mentioned stack efficiency or The steps to identify whether a fuel cell failure has occurred include:

[0043] The stack efficiency or With preset efficiency threshold or 0Compare, if or < or 0 , the battery stack fails, and the next step is executed. or ≥ or 0 , the battery stack has not failed;

[0044] Control the fuel cell engine to shut down and issue an early warning of stack failure.

[0045] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0046] 1. After starting the fuel cell engine, check whether there is any fault in the hydrogen circuit, air circuit and coolant circuit components. If there is a fault, do not start the fuel cell engine. Start the fuel cell engine when there is no fault in the above components to ensure the normal startup and operation of the fuel cell system.

[0047] 2. Make the fuel cell stack run at the current of the set operating point, and control the air compressor and hydrogen injection equipment according to the set speed and duty cycle, so that the air and hydrogen flow rates enter the stack according to the target volume flow rates.

[0048] 3. According to the electrochemical reaction formula, the theoretical output energy of the reaction gas consumption can be calculated. Q , calculate the actual output power according to the stack output voltage and current Q 1 , calculate the theoretical heat generation of the stack in real time based on the temperature rise of the coolant Q 0 , and then obtain the stack efficiency or , to diagnose the failure of the fuel cell stack. Compared with calculating the efficiency of the fuel cell stack through the polarization curve, the calculation accuracy is greatly improved.

[0049] 4. This method is applicable to all working conditions and can identify the stack efficiency at the current moment or , and is not affected by the reduction in efficiency caused by performance degradation of the battery stack.

[0050] On the other hand, an embodiment of the present invention further provides a fuel cell stack failure diagnosis device, comprising:

[0051] The operation status identification unit is used to start the fuel cell engine and determine whether it is in a normal startup and operation state. If so, the stack efficiency solution unit is started. Otherwise, a prompt message is issued to further troubleshoot the hydrogen path, air path, and coolant path failures of the fuel cell engine.

[0052] The stack efficiency calculation unit is used to control the stack to operate at the current of the set operating point after startup, and obtain the oxygen mass entering the stack within the set period from the current moment m 1, Hydrogen quality m 2 , oxygen concentration of the mixed gas leaving the reactor c , Hydrogen concentration d , and then the theoretical output energy of the reaction gas consumption is obtained Q ; and, obtain the actual output power of the battery stack Q 1 and heat production Q 0 , combined with the above energy Q The stack efficiency or , the obtained stack efficiency or Send to a fault identification unit;

[0053] The fault identification unit is used to identify whether the fuel cell stack has a failure fault based on the received fuel cell stack efficiency η, and output the identification result.

[0054] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the disclosure, nor is it intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0056] Figure 1 A schematic diagram of the steps of the failure diagnosis method for a fuel cell stack in Example 1 is shown;

[0057] Figure 2 A schematic diagram showing the principle of the failure fault diagnosis method for a fuel cell stack in Example 2 is shown. DETAILED DESCRIPTION

[0058] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0059] As used herein, the term "including" and its variations mean open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "based at least in part on". The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0060] Example 1

[0061] One embodiment of the present invention discloses a method for diagnosing a failure of a fuel cell stack. Figure 1 As shown, the following steps are included:

[0062] S1. Start the fuel cell engine and make sure it is in normal operation;

[0063] Specifically, in addition to the method of Example 2, it is also possible to determine whether the fuel cell engine is in normal operation by checking whether the output current, voltage, power, etc. of the fuel cell stack reaches a set range, which can be understood by those skilled in the art.

[0064] S2. Control the stack to operate at the current of the set operating point and obtain the oxygen mass entering the stack within the set period from the current moment. m 1 , Hydrogen quality m 2 , oxygen concentration of the mixed gas leaving the reactor (also called tail gas) c , Hydrogen concentration d , and then the theoretical output energy of the reaction gas consumption is obtained Q ;

[0065] Specifically, in addition to the method of Example 2, the oxygen concentration of the gas entering the stack can also be obtained by using a corresponding gas concentration sensor. a , Hydrogen concentration b , and then obtain the oxygen mass entering the reactor within the set period from the current moment m 1 , Hydrogen quality m 2 Theoretical output energy of the gas consumed by the reaction Q The calculation method of can also be found in CN202111014226.3.

[0066] The set operating point may refer to the power under the set operating condition, including at least one of the power under the open circuit idle condition, the variable load condition, the steady state condition, and the start-stop condition. The method may be verified for multiple operating conditions.

[0067] S3. Obtain the actual output power of the battery stackQ 1 and heat production Q 0 , combined with the above energy Q The stack efficiency or ;

[0068] Specifically,

[0069] or =( Q 0 + Q 1 ) / Q ,

[0070] S4. Based on the above stack efficiency or Identify whether the battery stack has failed;

[0071] Specifically, in addition to the method of Example 2, the stack efficiency can also be identified or Whether a failure occurs or not is determined by whether it is within a set range, which can be understood by those skilled in the art.

[0072] Compared with the prior art, the failure fault diagnosis method provided in this embodiment provides a method for accurately calculating the efficiency of the battery stack in real time. or A new method for diagnosing failure of battery stacks is also developed. This method can be used to diagnose failure of all current battery stacks. When the tested battery stack fails, the battery stack is shut down in time to avoid irreversible damage to the battery stack, effectively extending the service life of the battery stack.

[0073] Example 2

[0074] Based on the improvement of Example 1, the step S1 further comprises:

[0075] S11. Start the fuel cell engine;

[0076] S12. Detect whether the hydrogen path of the fuel cell engine is faulty (obtained by detecting key test index parameters, such as the output gas flow or pressure of the hydrogen injection device). If it is faulty, control the fuel cell engine to shut down and issue a warning of hydrogen path fault. Otherwise, execute step S13;

[0077] S13. Detect whether the air path of the fuel cell engine is faulty (obtained by detecting key test index parameters, such as the speed of the air compressor, the output gas flow rate or pressure). If it is faulty, control the fuel cell engine to shut down and issue an air path fault warning. Otherwise, execute step S14;

[0078] S14. Detect whether the coolant circuit of the fuel cell engine is faulty (obtained by detecting key test index parameters, such as the speed of the fan, the heating or cooling rate of the coolant). If faulty, control the fuel cell engine to shut down and issue a warning of coolant circuit fault. Otherwise, determine that the fuel cell engine is in normal startup and operation state.

[0079] Through the above steps S11 to S14, faults in the hydrogen path, air path, and coolant path of the fuel cell stack can be eliminated, and then fuel cell stack failure diagnosis can be performed.

[0080] Preferably, step S2 further comprises:

[0081] S21. Obtaining the amplitude of the output current of the battery stack at a set operating point;

[0082] S22. Determine the theoretical speed of the air compressor and the theoretical duty cycle of the hydrogen injection device corresponding to the amplitude of the current (determined by testing), control the air compressor to operate at the theoretical speed, and control the hydrogen injection device to operate at the theoretical duty cycle to ensure that the stack operates at the current of the set operating point (constant power);

[0083] S23. Obtain the mass concentration of oxygen in the air at the current moment r 1 、 The volume of air entering the pile per unit time V 1 The oxygen mass entering the reactor during the set period is obtained by the following formula: m 1 ,

[0084] m 1 = r 1 V 1 ,

[0085] S24. Obtain the mass concentration of hydrogen at the hydrogen supply end of the fuel cell engine at the current moment r 2 、 The volume of hydrogen entering the reactor per unit time V 2 The following formula is used to calculate the mass of hydrogen entering the reactor during the set period: m 2 ,

[0086] m 2 = r 2 V 2 ,

[0087] S26. The oxygen concentration of the stack mixed gas is collected in real time through the oxygen concentration sensor installed in the tail exhaust pipe. c ;

[0088] S27. The hydrogen concentration of the stack mixed gas is collected in real time through the hydrogen concentration sensor installed in the tail exhaust pipe. d ;

[0089] S28. Obtain the volume of mixed gas discharged from the stack per unit time V (The volume of air is equal to the volume of hydrogen), and the mass of oxygen consumed by the reaction is obtained by the following formula ∆ 1 , Hydrogen mass ∆ 2 ,

[0090] ∆ 1 = m 1 - CV ,

[0091] ∆ 2 = m 2 - dV ,

[0092] S29. The mass of oxygen consumed by the above reaction ∆ 1 (Unit: kg), Hydrogen mass ∆ 2 (Unit: kg), combined with the specific electrochemical reaction in the fuel cell stack, the theoretical output energy of the reaction consumed gas is obtained Q .

[0093] Specifically, Q The final calculation formula is as follows:

[0094] Q= 147.9∆ 2 -3.38∆ 1 ,

[0095] Q The unit is kJ. The derivation process can be found in the corresponding electrochemical reference book. The two-electron reaction process of oxygen reduction reaction is considered. The above formula is only applicable to ambient conditions of normal temperature and pressure. For ambient conditions of very high temperature and pressure, it can be obtained through further laboratory calibration.

[0096] Preferably, step S3 further comprises:

[0097] S31. Get the real-time output voltage of the battery stack V , Current I ;

[0098] S32. According to the above voltage V , Current I The actual output power of the battery stack is obtained by the following formula:Q 1 ,

[0099] ,

[0100] In the formula, t For time, T To set the time;

[0101] S33. Get the set time T Internal coolant temperature rise ∆K The heat generation of the battery stack is obtained by the following formula: Q 0 ,

[0102] ,

[0103] In the formula, C 1 For the hot melt of the coolant, M 1 is the mass of the coolant;

[0104] S34. The stack efficiency is calculated by the following formula or ,

[0105] or =( Q 0 + Q 1 ) / Q .

[0106] Preferably, step S4 further comprises:

[0107] S41. The stack efficiency or With preset efficiency threshold or 0 Compare, if or < or 0 , the battery stack fails, and the next step is executed. or ≥ or 0 , the battery stack has not failed;

[0108] S42. Control the fuel cell engine to shut down and issue a warning of stack failure.

[0109] The principle of the above method can be found in Figure 2 .

[0110] Compared with Example 1, the method provided in this example has the following beneficial effects:

[0111] 1. After starting the fuel cell engine, check whether there is any fault in the hydrogen circuit, air circuit and coolant circuit components. If a fault occurs, do not start the fuel cell engine. Start the fuel cell engine when there is no fault in the above components to ensure that the fuel cell system starts and runs normally.

[0112] 2. Make the fuel cell stack operate at the current of the set operating point, and control the air compressor and hydrogen injection equipment according to the set speed and duty cycle, so that the air and hydrogen flow rates enter the stack according to the target volume flow rates.

[0113] 3. According to the electrochemical reaction formula, the theoretical output energy of the reaction gas consumption can be calculated. Q , calculate the actual output power according to the stack output voltage and current Q 1 , calculate the theoretical heat generation of the stack in real time based on the temperature rise of the coolant Q 0 , and then obtain the stack efficiency or , to diagnose the failure of the fuel cell stack. Compared with calculating the efficiency of the fuel cell stack through the polarization curve, the calculation accuracy is greatly improved.

[0114] 4. This method is applicable to all working conditions and can identify the efficiency of the battery stack within a set period of time or , and is not affected by the reduction in efficiency caused by performance degradation of the battery stack.

[0115] Example 3

[0116] The present invention also provides a fuel cell stack failure fault diagnosis device corresponding to the methods of embodiments 1 and 2, comprising an operation status identification unit, a stack efficiency calculation unit, and a fault identification unit connected in sequence.

[0117] The operating status identification unit is used to start the fuel cell engine and determine whether it is in a normal startup and operation state. If so, the stack efficiency calculation unit is started. Otherwise, a prompt message is issued to further check the hydrogen circuit, air circuit, and coolant circuit faults of the fuel cell engine.

[0118] The stack efficiency calculation unit is used to control the stack to operate at the current of the set operating point after startup, and obtain the oxygen mass entering the stack within the set period from the current moment m 1 , Hydrogen quality m 2 , oxygen concentration of the mixed gas leaving the reactor c , Hydrogen concentration d , and then the theoretical output energy of the reaction gas consumption is obtained Q ; and, obtain the actual output power of the battery stack Q 1 and heat production Q0 , combined with the above energy Q The stack efficiency or , the obtained stack efficiency or Sent to the fault identification unit.

[0119] A fault identification unit is used to identify the above-mentioned stack efficiency according to the received or Identify whether the battery stack has a failure and output the identification result.

[0120] The embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terms used herein are selected to best explain the principles of the embodiments, practical applications, or improvements over the prior art, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for diagnosing a failure of a fuel cell stack, characterized in that: Includes steps: Start the fuel cell engine and make sure it is in normal operation; Control the stack to operate at the current of the set operating point, obtain the oxygen mass m1, hydrogen mass m2, oxygen concentration c, and hydrogen concentration d of the mixed gas leaving the stack within the set period from the current moment, and then obtain the theoretical output energy Q of the reaction consumed gas, including: The mass concentration of oxygen in the air at the current moment ρ1 and the volume of air entering the reactor per unit time V1 are obtained respectively, and the mass of oxygen entering the reactor within the set time period m1 is obtained by the following formula: m1=ρ1V1, The mass concentration ρ2 of hydrogen at the hydrogen supply end of the fuel cell engine at the current moment and the volume V2 of hydrogen entering the stack per unit time are obtained respectively, and the mass m2 of hydrogen entering the stack within the set time period is obtained by the following formula: m2=ρ2V2; The oxygen concentration c of the stack mixed gas is collected in real time through the oxygen concentration sensor installed in the tail exhaust pipe; The hydrogen concentration d of the stack mixed gas is collected in real time through the hydrogen concentration sensor installed in the tail exhaust pipe; Get the volume V of the mixed gas leaving the reactor per unit time, and use the following formula to get the oxygen mass Δ1 and hydrogen mass Δ2 consumed by the reaction: Δ1=m1-cV, Δ2=m2-dV, According to the oxygen mass Δ1 and hydrogen mass Δ2 consumed in the above reaction, combined with the specific electrochemical reaction in the fuel cell stack, the theoretical output energy Q of the gas consumed in the reaction is obtained. Q = 147.9Δ2-3.38Δ1; Obtain the actual output power Q1 and heat generation Q0 of the battery stack, and combine the above energy Q to obtain the battery stack efficiency η; The actual output power Q1 and heat generation Q0 of the battery stack are obtained through the following steps: Obtain the real-time output voltage V and current I of the battery stack; According to the above voltage V and current I, the actual output power Q1 of the battery stack is obtained by the following formula: In the formula, t is time, T is the set time; Get the temperature rise ΔK of the coolant within the set time T, and use the following formula to get the heat generation Q0 of the stack: Q0=C1M1ΔK, In the formula, C1 is the heat of the coolant, and M1 is the mass of the coolant; The stack efficiency η is obtained by the following formula: η=(Q0+Q1) / Q; Identifying whether a failure occurs in the battery stack according to the battery stack efficiency η further includes: Compare the stack efficiency η with a preset efficiency threshold η0. If η<η0, the stack fails, and the next step is executed. If η≥η0, the stack does not fail. Control the fuel cell engine to shut down and issue an early warning of stack failure.

2. The method for diagnosing a failure of a fuel cell stack according to claim 1, characterized in that: The step of starting the fuel cell engine and determining that it is in a normal startup and operation state further includes: Starting the fuel cell engine; Detect whether the hydrogen path of the fuel cell engine is faulty. If so, control the fuel cell engine to shut down and issue a hydrogen path fault warning. Otherwise, proceed to the next step. Detect whether the air path of the fuel cell engine is faulty. If so, control the fuel cell engine to shut down and issue an air path fault warning. Otherwise, execute the next step. Check whether the coolant circuit of the fuel cell engine is faulty. If so, control the fuel cell engine to shut down and issue a warning of the coolant circuit fault. Otherwise, make sure that the fuel cell engine is in a normal startup and operation state.

3. The fuel cell stack failure diagnosis method according to claim 1 or 2, characterized in that: The step of controlling the battery stack to operate at a current of a set operating point further includes: Obtain the amplitude of the output current of the battery stack at a set operating point; Determine the theoretical speed of the air compressor and the theoretical duty cycle of the hydrogen injection device corresponding to the amplitude of the above current, control the air compressor to operate at the above theoretical speed, and control the hydrogen injection device to operate at the theoretical duty cycle to ensure that the fuel cell stack operates at the current of the set operating point.

4. A fuel cell stack failure diagnosis device, characterized in that: The device performs the method according to any one of claims 1 to 3, including: The operation status identification unit is used to start the fuel cell engine and determine whether it is in a normal startup and operation state. If so, the stack efficiency solution unit is started. Otherwise, a prompt message is issued to further troubleshoot the hydrogen path, air path, and coolant path failures of the fuel cell engine. The stack efficiency calculation unit is used to control the stack to operate at the current of the set operating point after startup, obtain the mass of oxygen m1 and the mass of hydrogen m2 entering the stack within the set period from the current moment, the oxygen concentration c and the hydrogen concentration d of the mixed gas leaving the stack, and then obtain the theoretical output energy Q of the reaction consumed gas, including: The mass concentration of oxygen in the air at the current moment ρ1 and the volume of air entering the reactor per unit time V1 are obtained respectively, and the mass of oxygen entering the reactor within the set time period m1 is obtained by the following formula: m1=ρ1V1, The mass concentration ρ2 of hydrogen at the hydrogen supply end of the fuel cell engine at the current moment and the volume V2 of hydrogen entering the stack per unit time are obtained respectively, and the mass m2 of hydrogen entering the stack within the set time period is obtained by the following formula: m2=ρ2V2; The oxygen concentration c of the stack mixed gas is collected in real time through the oxygen concentration sensor installed in the tail exhaust pipe; The hydrogen concentration d of the stack mixed gas is collected in real time through the hydrogen concentration sensor installed in the tail exhaust pipe; Get the volume V of the mixed gas leaving the reactor per unit time, and use the following formula to get the oxygen mass Δ1 and hydrogen mass Δ2 consumed by the reaction: Δ1=m1-cV, Δ2=m2-dV, According to the oxygen mass Δ1 and hydrogen mass Δ2 consumed in the above reaction, combined with the specific electrochemical reaction in the fuel cell stack, the theoretical output energy Q of the gas consumed in the reaction is obtained. Q = 147.9Δ2-3.38Δ1; And, obtaining the actual output electric energy Q1 and heat generation Q0 of the battery stack, combining the energy Q to obtain the battery stack efficiency η, and sending the obtained battery stack efficiency η to the fault identification unit; The fault identification unit is used to identify whether the fuel cell stack has a failure fault based on the received fuel cell stack efficiency η, and output the identification result.

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