Fuel cell pulse emission control method and system

Abstract

The invention relates to a pulse emission control method for a fuel cell. The method comprises the following steps: S1, starting up the fuel cell; recording the power-on duration; the pulse row frequency is reset; s2, performing first pulse arrangement after the fuel cell is started for a first time threshold value; adding 1 to the pulse arrangement frequency; s3, starting timing from the end of the last pulse arrangement to obtain accumulated time after the pulse arrangement; s4, when the accumulated time after pulse arrangement is smaller than a second time threshold value, the voltage value Un is collected once every one second, and the voltage fluctuation value delta Un of two adjacent times of collection is calculated in real time; when delta Un is larger than or equal to e * Un, two times of continuous discharging are carried out, and 1 is added to the pulse discharging frequency after each time of discharging; the two times of continuous discharge comprise first pulse pre-discharge and pulse post-discharge; returning to the step S3 until the fuel cell is shut down; when the accumulated time after pulse arrangement is larger than or equal to a second time threshold value, two times of continuous arrangement are carried out, the two times of continuous arrangement comprise second pulse pre-arrangement and pulse post-arrangement, and one is added to the pulse arrangement frequency after each time of arrangement; and returning to the step S3 until the fuel cell is shut down.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fuel cells, in particular to a fuel cell pulse discharge control method and system. BACKGROUND

[0002] Water is generated during the operation of a fuel cell, and the generated water continuously accumulates inside the stack, which can cause flow passage blockage, affect the airflow distribution inside the stack, cause local gas deficiency of the fuel cell stack, affect the stable operation of the fuel cell, and even cause local temperature of the fuel cell to be too high, affecting the safe and reliable operation of the fuel cell. A pulse discharge valve is usually used to control hydrogen discharge during the operation of the fuel cell, and the pulse discharge can discharge water inside the fuel cell to ensure that the water management of the stack is in a good state. The pulse discharge can discharge a part of hydrogen, causing hydrogen waste. Therefore, it is necessary to reduce the hydrogen consumption while ensuring the discharge of water, ensure reliable operation, improve the utilization rate of hydrogen, and improve the efficiency of the fuel cell.

[0003] The patent CN116454325A sets the pulse discharge mode by simulating extreme working scenarios, performs pulse discharge by starting, loading and unloading, and formulates a pulse discharge strategy by simulating extreme operating states to ensure a good water management state of the fuel cell. However, the patent does not consider the hydrogen utilization rate of the fuel cell, which reduces the hydrogen utilization rate of the fuel cell and reduces the efficiency of the fuel cell.

[0004] The patent CN11731730A uses current to control pulse discharge, which cannot accurately reflect the pulse discharge timing of the fuel cell, causing the fuel cell to discharge water in time, or causing hydrogen waste by discharging water in a state without the need to discharge water. SUMMARY

[0005] In view of the above analysis, the embodiments of the present application aim to provide a fuel cell pulse discharge control method and system to solve the problems of the existing hydrogen fuel cell pulse discharge that discharges water in time or has a low hydrogen utilization rate.

[0006] The embodiments of the present application provide a fuel cell pulse discharge control method, which comprises the following steps:

[0007] S1, starting the fuel cell; recording the starting time of the fuel cell; clearing the pulse discharge times; using the fuel cell controller to control the gear position of the air compressor according to the loading state of the fuel cell;

[0008] S2, when the starting time of the fuel cell is greater than a first time threshold, the fuel cell performs a first pulse discharge; and the pulse discharge times are incremented by 1;

[0009] S3, starting timing from the end time of the last pulse discharge to obtain the cumulative time after pulse discharge;

[0010] S4, when the cumulative time after the pulse discharge is less than the second time threshold, every first interval time t g Collecting hydrogen fuel cell stack voltage value U n Real-time calculation of voltage fluctuation value ΔU of hydrogen fuel cell stack voltage collected adjacent twice n ; when the voltage fluctuation value ΔU n Is greater than or equal to the voltage comparison threshold, two consecutive discharges are carried out, and the number of pulse discharges is increased by 1 after each discharge; the two consecutive discharges include the first pulse pre-discharge and the pulse post-discharge; return to step S3 until the fuel cell is shut down;

[0011] When the cumulative time after the pulse discharge is greater than or equal to the second time threshold, two consecutive discharges are carried out, and the number of pulse discharges is increased by 1 after each discharge; the two consecutive discharges include the second pulse pre-discharge and the pulse post-discharge; return to step S3 until the fuel cell is shut down.

[0012] Further, when the voltage fluctuation value ΔU of hydrogen fuel cell stack voltage collected adjacent twice n Is less than the voltage comparison threshold, the fuel cell does not carry out pulse discharge, and returns to step S3.

[0013] Further, when the pulse post-discharge is carried out, the discharge time is determined according to the number of pulse discharges N;

[0014] If N is an integer multiple of a fixed integer value c, the pulse post-discharge time is set to t m , wherein c is an integer from 3 to 5; if N is not an integer multiple of c, the pulse discharge time is set to 1-1.5s.

[0015] Further, the pulse post-discharge time t m Is:

[0016] t m =d·c,

[0017] Wherein d is the pulse discharge time coefficient, and d ranges from 0.4 to 0.6.

[0018] Further, when the second pulse pre-discharge is carried out, the discharge time is set according to the gear of the air compressor, if the air compressor gear is greater than 1, the discharge time is set to 0.8-1 second; if the air compressor gear is equal to 1, the discharge time is set to 0.5-0.8 second.

[0019] Further, when the first pulse pre-discharge is carried out, the discharge time is set to 1-1.2 seconds.

[0020] Further, the voltage comparison threshold is e·U n ; wherein e=0.05-0.08, e is the pulse discharge voltage judgment coefficient, and U nThe nth hydrogen fuel cell stack voltage value recorded by the voltage patrol instrument.

[0021] Further, the first time threshold is 50-70 seconds, and the discharge time of the first pulse discharge of the fuel cell is 2-3 seconds.

[0022] Further, the second time threshold is 100-150 seconds, and the first interval time t g is 1 second.

[0023] Further, in the control method, the voltage patrol instrument is used to collect the hydrogen fuel cell stack voltage value U n , and the voltage fluctuation value ΔU n is the absolute value of the difference between the hydrogen fuel cell stack voltages collected at adjacent times.

[0024] The fuel cell controller is used to control the opening and closing of the fuel cell pulse discharge valve and the opening time control of the pulse discharge valve.

[0025] Compared with the prior art, the present application can achieve at least one of the following beneficial effects:

[0026] 1. In the method of the present application, the first pulse discharge control of the fuel cell during startup is used to remove residual impurity gas, improve the gas quality of the fuel cell stack, facilitate the water and heat management control of the fuel cell, and improve the variable load reliability of the fuel cell.

[0027] 2. In the method of the present application, the cumulative time after the pulse discharge of the fuel cell is used to indirectly reflect the water distribution state of the fuel cell stack flow channel manifold, determine the pulse discharge time of the fuel cell, and improve the hydrogen utilization rate.

[0028] 3. In the method of the present application, the air compressor gear position is used to determine the running load state of the fuel cell, ensure the water discharge reliability of the fuel cell in a high load state, ensure the stable operation of the fuel cell, reduce the pulse discharge time in a low load state, reduce hydrogen loss, and improve the hydrogen utilization rate.

[0029] 4. In the method of the present application, the cumulative number of pulse discharges is used to make a deep-level judgment of the water management of the fuel cell, ensure that the fuel cell is in an optimal water management state, and ensure the stable and reliable operation of the fuel cell.

[0030] 5. The present application is a new type of pulse discharge control method for a hydrogen fuel cell, which uses the startup time of the fuel cell, the pulse discharge coefficient, the cumulative time of the pulse discharge, the air compressor gear position, and the fuel cell voltage change value to comprehensively determine the water management state of the fuel cell, selects the optimal pulse discharge strategy under different states, ensures that the water management of the fuel cell operates well, achieves stable operation of the fuel cell, saves the amount of hydrogen used, improves the hydrogen utilization rate, improves the performance of the fuel cell, and improves the energy efficiency of the fuel cell.

[0031] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0033] Figure 1 The present invention is a flow chart of a fuel cell pulse emission control method and system method. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0035] A specific embodiment of the present invention discloses a fuel cell pulse emission control method and system, the method flow chart is as follows Figure 1 Specifically including steps S1-S4.

[0036] S1. Turn on the fuel cell; record the fuel cell startup time; reset the pulse emission times; and control the air compressor gear using the fuel cell controller according to the fuel cell loading status.

[0037] Specifically, the fuel cell controller records the fuel cell's power-on time and pulse emission frequency. The air compressor's gears range from 1 to K. The greater the load on the battery, the higher the gear setting needs to be, with 1 being the lowest and K being the highest.

[0038] S2. When the fuel cell startup time is greater than the first time threshold, the fuel cell performs the first pulse discharge; the number of pulse discharges increases by 1.

[0039] The first time threshold is 50-70 seconds, and the discharge time when the fuel cell performs the first pulse discharge is 2-3 seconds.

[0040] Specifically, through experiments, it was found that when the fuel cell is just turned on, due to the low temperature, almost no water is produced. The water accumulates to a certain amount in 50-70 seconds. This time is selected as the first drainage time. After 2-3 seconds, the water in the fuel cell can be fully discharged.

[0041] S3. Start timing from the end time of the last pulse discharge to obtain the accumulated time after the pulse discharge.

[0042] Specifically, the fuel cell performs first pulse discharge to obtain pulse discharge cumulative time; the pulse discharge cumulative time is reset at the end of each pulse discharge, except the first pulse discharge.

[0043] S4, when the pulse discharge cumulative time is less than the second time threshold, the pulse discharge is performed every first interval time t g collecting the hydrogen fuel cell stack voltage value U n , calculating the voltage fluctuation value ΔU n of the adjacent two collected hydrogen fuel cell stack voltages in real time n ; when the voltage fluctuation value ΔU n is greater than or equal to the voltage comparison threshold, performing two continuous discharges, and the pulse discharge number after each discharge is increased by 1; the two continuous discharges include the first pulse pre-discharge and the pulse post-discharge; returning to step S3 until the fuel cell is shut down;

[0044] when the pulse discharge cumulative time is greater than or equal to the second time threshold, performing two continuous discharges, and the pulse discharge number after each discharge is increased by 1; returning to step S3 until the fuel cell is shut down.

[0045] It can be understood that, whether it is the two continuous discharges performed when the pulse discharge cumulative time is less than the second time threshold, or the two continuous discharges performed when the pulse discharge cumulative time is greater than or equal to the second time threshold, the two continuous discharges are returned to step S3 to recalculate the pulse discharge cumulative time.

[0046] In the control method, the voltage patrol instrument is used to collect the hydrogen fuel cell stack voltage value U n , and the voltage fluctuation value ΔU n is the absolute value of the difference between the adjacent two collected hydrogen fuel cell stack voltages;

[0047] The fuel cell controller is used to control the opening and closing of the fuel cell pulse discharge valve, and to control the pulse discharge valve opening time.

[0048] The second time threshold is 100-150 seconds, and the first interval time t g is 1 second.

[0049] The voltage comparison threshold is e·U n ; wherein e=0.05-0.08, e is the pulse discharge voltage judgment coefficient, and U n is the nth hydrogen fuel cell stack voltage value recorded by the voltage patrol instrument.

[0050] When performing the first pulse pre-discharge, the discharge time is set to 1-1.2 seconds.

[0051] When the post-pulse emission is performed, the emission time is determined according to the pulse emission number N;

[0052] If N is an integer multiple of a fixed integer value c, the post-pulse emission time is set to t m , where c takes an integer from 3 to 5; if N is not an integer multiple of c, the pulse emission time is set to 1-1.5s.

[0053] The post-pulse emission time t m is:

[0054] t m = d·c,

[0055] where d is a pulse emission time coefficient, and d ranges from 0.4 to 0.6.

[0056] Specifically, when N = c·f, f is a natural number, the post-pulse emission time is set to t m , i.e., t m time of pulse emission is performed every c natural number pulse emission period, and the emission time of the rest of the post-pulse emission is set to 1-1.5s. This setting is to further distinguish according to the actual situation at each pulse emission, so as to finely plan the pulse emission time, save hydrogen, and achieve timely and sufficient drainage effect. Through experiments, it is proved that when the emission number is an integer multiple of c, a longer emission time (t m ) is performed once, and when the emission number is not an integer multiple of c, a shorter emission time (1-1.5s) is selected. Through the above fine setting of the emission time, the water in the fuel cell can be fully drained, and the water can be fully drained without excessive emission, thereby realizing the full drainage of water on the basis of saving hydrogen.

[0057] When the voltage fluctuation value ΔU n of the hydrogen fuel cell stack voltage collected at adjacent two times is less than the voltage comparison threshold value, the fuel cell does not perform pulse emission, and returns to step S3.

[0058] Specifically, when the voltage fluctuation value ΔU n of the hydrogen fuel cell stack voltage collected at adjacent two times is less than the voltage comparison threshold value, it indicates that the battery operating condition is relatively stable, and pulse emission is not performed, and returns to step S3 to continue detecting the voltage fluctuation value until it is greater than the second time threshold value. After reaching the second time threshold value, the judgment of the air compressor gear position is performed, if it is greater than or equal to 2 gears, the pulse emission time is considered to be longer due to the larger load, if the air compressor gear position is equal to 1 gear, the emission time is considered to be shorter due to the smaller load.

[0059] When the second pulse is discharged, the discharge time is set according to the gear of the air compressor. If the gear of the air compressor is greater than 1, the discharge time is set to 0.8-1 seconds; if the gear of the air compressor is equal to 1, the discharge time is set to 0.5-0.8 seconds.

[0060] When the cumulative time after the pulse discharge reaches the second time threshold, the discharge time is set according to the gear. The higher the gear, the longer the discharge time. Therefore, the above discharge time setting can set a reasonable discharge time according to the working condition, and ensure the full discharge of water on the basis of solving hydrogen.

[0061] Compared with the prior art, the fuel cell start-up first pulse discharge control provided by the embodiment can remove residual impurity gas, improve the gas quality of the fuel cell stack, and perform first fuel cell water and heat management control to improve the load change reliability of the fuel cell. The cumulative time after the pulse discharge of the fuel cell indirectly reflects the water distribution state of the fuel cell stack flow channel manifold, the pulse discharge time of the fuel cell is determined, and the hydrogen utilization rate is improved. The air compressor gear is used to determine the running load state of the fuel cell. In the high load state, the fuel cell drainage reliability is ensured, the fuel cell is stably operated, the pulse discharge time is reduced in the low load state, the hydrogen loss is reduced, and the hydrogen utilization rate is improved. The pulse discharge cumulative number is used for deep-level judgment of fuel cell water management, the fuel cell is ensured to be in an optimal water management state, and the stable and reliable operation of the fuel cell is ensured. The fuel cell start-up time, the pulse discharge coefficient, the pulse discharge cumulative time, the air compressor gear and the fuel cell voltage change value are used to comprehensively judge the fuel cell water management state, the optimal pulse discharge strategy is selected in different states, the fuel cell water management is ensured to be in good operation, the fuel cell is stably operated, the hydrogen usage amount is saved, the hydrogen utilization rate is improved, the performance of the fuel cell is improved, and the energy efficiency of the fuel cell is improved.

[0062] Those skilled in the art can understand that all or part of the processes of the above-mentioned embodiments can be completed by a computer program instructing related hardware, and the program can be stored in a computer readable storage medium. The computer readable storage medium includes a magnetic disk, an optical disk, a read-only memory or a random access memory.

[0063] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed by the present application can be easily thought by those skilled in the art, and should be covered within the protection scope of the present application.

Claims

1. A fuel cell pulse discharge control method characterized by, The method comprises: S1, starting the fuel cell; recording the starting time of the fuel cell; clearing the pulse discharge times; using the fuel cell controller to control the gear of the air compressor according to the loading state of the fuel cell; S2, when the starting time of the fuel cell is greater than the first time threshold, the fuel cell performs the first pulse discharge; the pulse discharge times are added by 1; S3, the pulse discharge time is accumulated from the end time of the last pulse discharge; S4, when the accumulated time after the pulse discharge is less than a second time threshold, every first interval time t g collecting hydrogen fuel cell stack voltage value U n , real-time calculation of voltage fluctuation value ΔU of hydrogen fuel cell stack voltage collected twice in succession n ; when the voltage fluctuation value ΔU n is greater than or equal to a voltage comparison threshold, two consecutive discharges are performed, and the number of pulse discharges after each discharge is increased by 1; the two consecutive discharges include a first pulse pre-discharge and a pulse post-discharge; return to step S3 until the fuel cell is shut down; When the accumulated time after the pulse discharge is greater than or equal to the second time threshold, two continuous discharges are performed, the two continuous discharges comprise a second pulse pre-discharge and a pulse post-discharge, the pulse discharge times are added by 1 after each discharge; return to step S3 until the fuel cell is shut down.

2. The pulse discharge control method according to claim 1, characterized by, When the voltage fluctuation value ΔU of the hydrogen fuel cell stack voltage collected at two adjacent times n is less than the voltage comparison threshold value, the fuel cell does not perform pulse discharge, and returns to step S3.

3. The pulse discharge control method according to claim 1, characterized by, When the pulse post-discharge is performed, the discharge time is determined according to the pulse discharge times N; If N is an integer multiple of the fixed integer value c, the post-pulse discharge time is set to t m where c takes integer values from 3 to 5; if N is not an integer multiple of c, the post-pulse discharge time is set to 1-1.5 s.

4. The pulse discharge control method according to claim 3, characterized by, Post-pulse discharge time t m is: t m = d - c, Wherein d is the pulse discharge time coefficient, the range of d is 0.4-0.

6.

5. The pulse discharge control method according to claim 1, characterized by, When the second pulse pre-discharge is performed, the discharge time is set according to the gear of the air compressor, if the gear of the air compressor is greater than 1, the discharge time is set to 0.8-1 second; if the gear of the air compressor is equal to 1, the discharge time is set to 0.5-0.8 second.

6. The pulse discharge control method according to claim 1, characterized by, When the first pulse pre-discharge is performed, the discharge time is set to 1-1.2 second.

7. The pulse discharge control method according to claim 1, characterized by, The voltage comparison threshold is e•U n ; where e = 0.05-0.08, e is a pulse discharge voltage judgment coefficient, U n is the nth hydrogen fuel cell stack voltage value recorded by the voltage patrol instrument.

8. The pulse discharge control method according to claim 1, characterized by, The first time threshold is 50-70 seconds, and the discharge time of the first pulse discharge is 2-3 seconds.

9. The pulse discharge control method according to claim 1, characterized by, The second time threshold is 100-150 seconds, the first interval time t g is 1 second.

10. The pulse discharge control method according to any one of claims 1 to 9, characterized by, The control method adopts a voltage detector to collect hydrogen fuel cell stack voltage value U n , voltage fluctuation value ΔU n The absolute value of the difference between the hydrogen fuel cell stack voltage collected at adjacent two times is taken. The fuel cell controller is used to control the opening or closing of the fuel cell pulse discharge valve and the opening time control of the pulse discharge valve.

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