Restart method and restart module for fuel cell system

Abstract

The invention relates to a restarting method of a fuel cell system. The restarting method comprises the following steps: recording downtime, measuring gas temperature and pressure in a cathode chamber and an anode chamber, and calculating the residual amount of air and hydrogen in the cathode chamber and the anode chamber; determining whether the residual gas after the shutdown process is air or hydrogen and the quantity of the residual gas based on the residual quantity of the air and the hydrogen; recording restarting time and calculating shutdown duration; when the residual gas is air, the amount of air contained in the anode chamber during restarting is determined as the final air amount, and the final hydrogen amount is 0; when the residual gas is hydrogen, the air leakage amount during the shutdown period is determined as the final air amount, and the final hydrogen amount is the residual gas amount; whether a purge operation needs to be performed during restart is determined based on the final air amount and the final hydrogen amount and an amount of hydrogen to be supplied is calculated when it is determined that the purge operation needs to be performed. The invention further relates to a restart module, a control subsystem and a machine readable medium for executing the method.

Description

Technical Field

[0001] The present invention relates to the field of fuel cells, and in particular to a restart method for a fuel cell system, a restart module for executing the restart method, a control subsystem including the restart module, and a computer (or machine) readable medium for implementing the restart method. Background Art

[0002] Fuel cell systems are widely used in vehicles to provide power due to their "zero-emission" characteristics, producing only liquid water as a product during use. A fuel cell system primarily comprises a fuel cell stack consisting of multiple cells; an air supply subsystem and a cathode exhaust subsystem associated with the stack's cathode chamber; and a hydrogen supply subsystem and an anode (or hydrogen) exhaust subsystem associated with the stack's anode chamber.

[0003] When a fuel cell system is restarted after a period of downtime, the presence of air inside the fuel cell stack, particularly in the anode chamber, can create a hydrogen-air interface. This creates a reverse current and potential difference between the hydrogen and air, accelerating corrosion of the carbon support in the cathode chamber. The increased pores in the carbon support correspondingly reduce the catalyst's ECSA (electrochemically active surface area), thus reducing the performance and life of the fuel cell stack.

[0004] In the prior art, when a fuel cell system is shut down, hydrogen can continue to be supplied to the anode chamber in order to consume any remaining air and reduce the likelihood of air entering the anode chamber during the shutdown period and forming the aforementioned interface within the anode chamber when the fuel cell system is restarted. This is known as a purge process.

[0005] However, during system shutdown, air may still leak into the fuel cell stack and into the anode chamber due to the limited sealing performance of the air supply valve of the air supply subsystem, forming a hydrogen-air interface when the system is restarted. Summary of the Invention

[0006] The purpose of this application is to associate the shutdown process or state of the fuel cell system and the leakage of air into the fuel cell stack through the air intake valve during shutdown (and optional hydrogen leakage) with the restart process, accurately determine the necessity of performing a purge operation during the restart process and achieve precise control of the purge operation.

[0007] In a first aspect of the present application, a restart method for a fuel cell system is provided. The fuel cell system includes a fuel cell stack having a cathode chamber and an anode chamber, an air supply subsystem communicating with the cathode chamber and having an air supply valve, and a hydrogen supply subsystem communicating with the anode chamber and having a hydrogen supply valve. The restart method includes:

[0008] a recording step of recording the downtime when the air supply valve is cut off and measuring the temperature and pressure of the gas in the cathode chamber and the anode chamber respectively;

[0009] a shutdown calculation step of calculating a remaining amount of air and a remaining amount of hydrogen in the cathode chamber and the anode chamber based on the gas temperature and pressure in the cathode chamber and the anode chamber measured in the recording step;

[0010] A shutdown state determination step of determining whether the remaining gas in the fuel cell stack after the fuel cell system shutdown process is air or hydrogen and the remaining gas amount based on the remaining air amount and the remaining hydrogen amount;

[0011] An initial step of recording a restart time of the fuel cell system and calculating a shutdown duration based on the shutdown time and the restart time;

[0012] If it is determined in the shutdown state determination step that the remaining gas is air, performing: an air measuring step of determining the amount of air contained in the anode chamber at the restart time and determining it as a final air amount and determining the final hydrogen amount to be 0;

[0013] If it is determined in the shutdown state determination step that the remaining gas is hydrogen, performing: an air leakage calculation step of determining an amount of air leaked into the fuel cell stack through the air supply valve during shutdown and determining it as a final air amount and determining the final hydrogen amount as the gas amount determined in the shutdown state determination step;

[0014] performing, based on the final air amount and the final hydrogen amount determined in the air measuring step or the air leakage calculating step: a determining step of determining whether a purge operation needs to be performed during the restart process; and

[0015] If it is determined in the determining step that the purge operation needs to be performed, a purge step of calculating the amount of hydrogen gas to be supplied in the purge operation and performing the purge operation is performed.

[0016] In a second aspect of the present application, a restart module for a fuel cell system is provided. The restart module includes a processor storing executable instructions. When the executable instructions are executed by the processor, the restart method described above is performed.

[0017] In a third aspect of the present application, a control subsystem for a fuel cell system is provided, which includes the above-mentioned restart module for the fuel cell system.

[0018] In a fourth aspect of the present application, a fuel cell system is provided, comprising: a fuel cell stack having a cathode chamber and an anode chamber, an air supply subsystem connected to the cathode chamber and having an air supply valve, a hydrogen supply subsystem connected to the anode chamber and having a hydrogen supply valve; and the above-mentioned restart module for the fuel cell system or the above-mentioned control subsystem for the fuel cell system.

[0019] In a fifth aspect of the present application, a machine-readable storage medium is provided, which includes a processor storing executable instructions, and the executable instructions perform the above-mentioned restart method when executed by the processor.

[0020] The method of the present application includes accurately judging the situation (or amount) of air and hydrogen present in the fuel cell stack when the fuel cell system is restarted based on the measurement and / or calculation of the amount of air and hydrogen present in the fuel cell stack during the shutdown process of the fuel cell system, and based on the measurement or calculation of the amount of air leaked into the fuel cell stack through the air intake valve during the shutdown period, so as to determine whether a purge operation to remove the air in the anode chamber should be performed during the restart process, and if it is determined that the purge operation is indeed required, the amount of hydrogen to be supplied in the purge operation is accurately calculated and controlled based on the calculation of the amount of air present at this time. On the one hand, this restart method ensures that no air is present in the anode chamber during restart of the fuel cell system, and no hydrogen-air interface is formed. This eliminates the potential adverse effects or damage to the fuel cell stack caused by this interface, thereby improving performance and extending life. On the other hand, this restart method selectively performs a purge operation only when calculations indicate that additional hydrogen is needed to react with the air within the anode chamber, rather than performing the purge operation during every restart. This avoids the possibility of unnecessary purge operations when not needed, thereby avoiding the resulting waste of hydrogen and time. Furthermore, the amount of hydrogen required for the purge operation, or the time required to supply hydrogen, is determined by the aforementioned calculations. This not only ensures that the air in the anode chamber is completely cleared, achieving the optimal purge effect, but also prevents excessive hydrogen supply and waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a simplified flow chart of a restart method for a fuel cell system according to the present application.

[0022] Figure 2 The figure shows the relationship between the valve leakage rate for air, valve temperature and the pressure difference between the inside and outside of the valve for a specific valve structure obtained through experiments.

[0023] Figure 3 FIG. 1 is a diagram showing the relationship between the pressure difference between the inside and outside of an air supply valve and the shutdown duration according to an example. DETAILED DESCRIPTION

[0024] The present application provides a restart method for a fuel cell system, which aims to associate the shutdown process of the fuel cell system and the leakage of air (and optional hydrogen) during the shutdown time or period with the restart process of the fuel cell system, especially the purge operation during the restart process (or also referred to as "purge process" in this article).

[0025] For the sake of clarity, before describing the method of the present application in detail, a brief introduction to the "fuel cell system" is first given. The "fuel cell system" involved in the present application can be a fuel cell system suitable for being mounted on or configured on any type of fuel cell vehicle, for generating and outputting electricity to drive the vehicle. In general, the fuel cell system includes a fuel cell stack (or group) consisting of an anode chamber, a cathode chamber and an electrolyte membrane, an air supply subsystem for supplying air to the cathode chamber of the fuel cell stack, a cathode exhaust subsystem for discharging reaction products (such as cathode exhaust gas and water) in the cathode chamber, a hydrogen supply subsystem for supplying hydrogen to the anode chamber of the fuel cell stack, and an anode (or hydrogen) exhaust subsystem for discharging excess hydrogen in the anode chamber.

[0026] The air supply subsystem mainly includes an air intake valve, an air compressor, an air supply pipeline, etc. The air compressor receives and compresses air from an air source, and then (when the air intake valve is turned on) supplies the compressed air to the cathode chamber (or cathode side) of the fuel cell stack via the air supply pipeline. The air supply subsystem may also include an air flow meter, which is, for example, arranged on the upstream side of the air compressor to measure the amount of air received by the air compressor. When the air intake valve is turned on, the above-mentioned compressed air is allowed to be supplied to the fuel cell stack, and when it is turned off, the air is prohibited from being supplied to the fuel cell stack. However, due to structural reasons, when the fuel cell system is shut down, especially when it is shut down for a long time, air may leak into the cathode chamber of the fuel cell stack through the air intake valve.

[0027] The hydrogen supply subsystem primarily includes a hydrogen inlet valve, a hydrogen supply source, and a hydrogen supply pipeline. When connected, the hydrogen inlet valve allows hydrogen from the hydrogen supply source to be supplied to the anode chamber (or anode side) of the fuel cell stack via the hydrogen supply pipeline. Furthermore, the hydrogen supply subsystem may also include a pressure measuring device and / or a pressure regulating device. Similar to the air inlet valve, hydrogen may leak from the hydrogen inlet valve into the anode chamber of the fuel cell stack when the fuel cell system is shut down, especially for an extended period.

[0028] The fuel cell system further includes a control subsystem, which may include a processor and a memory and is configured to control various structural components of the fuel cell system to control the execution of various functions or operations of the fuel cell system, for example, to enable the fuel cell stack to generate power that meets expected requirements. The restart module for executing the restart method of the fuel cell system of the present application can be provided independently of the control subsystem, or can be integrated into the control subsystem as part of the control subsystem of the fuel cell system, or the method can be directly executed by (the processor of) the control subsystem of the fuel cell system.

[0029] Herein, the "shutdown process" of the fuel cell system begins when the air intake valve is shut off; the term "shutdown time t1" specifically refers to the start time of the "shutdown process," i.e., the time when the air intake valve is shut off. The "shutdown process" includes shutting off the hydrogen intake valve (simultaneously or subsequently with the air intake valve), so the "shutdown process" lasts at least until both the air intake valve and the hydrogen intake valve are shut off. In some embodiments, the "shutdown process" may be executed in response to a power outage of the fuel cell system. In this case, the "shutdown process" may be a process in which both the air intake valve and the hydrogen intake valve are shut off simultaneously, such as in an unexpected or emergency shutdown. In some embodiments, the "shutdown process" may be executed in response to receiving a shutdown signal or command, such as in response to an operator operating a switch or button for shutting down the fuel cell system. In this case, the "shutdown process" may be a situation in which the air intake valve is shut off and the hydrogen intake valve is shut off simultaneously or subsequently. This process may ultimately end or terminate with the power outage of the fuel cell system.

[0030] Herein, the "restart process" of a fuel cell system begins when the fuel cell system receives a restart signal or command. The term "restart time t2" specifically refers to this start time of the "restart process." The "restart process" terminates or ends when both the air intake valve and the hydrogen intake valve are placed in the on state, at which point the fuel cell stack begins to operate, generate, and output electricity. The "restart signal or command" can be the powering on of the fuel cell system, or it can be the operator's operation of a switch or button for the restart function of the fuel cell system (the switch or button for the restart function can be, but is not necessarily, the same switch or button for the shutdown function). The "shutdown duration t0" refers to the time interval or period from "shutdown time t1" to "restart time t2."

[0031] With reference to the above explanations of specific terms, the restart method (or process) of the fuel cell system of the present application takes into account the shutdown process of the fuel cell system, the shutdown duration, and the leakage of air through the air supply valve to the interior of the fuel cell stack of the fuel cell system during the shutdown (duration) of the fuel cell system (optionally, the leakage of hydrogen through the hydrogen supply valve to the interior of the fuel cell stack can also be considered).

[0032] The advantages of the method of the present application are that, based on consideration of the above factors, it is determined by calculation whether air (and the amount of air) is contained in the fuel cell stack (or its anode chamber) at the beginning of the fuel cell system restart process (i.e., "restart time t2"), thereby determining whether a purge operation (to react or consume oxygen in the air) is required during the restart process (before the end of the "restart process" or before both the air intake valve and the hydrogen intake valve, especially the air intake valve, are placed in the on state), and when it is determined that a purge operation is required, the amount of hydrogen to be supplied during the purge operation is accurately calculated. The purge operation here specifically refers to reacting or consuming the existing air by supplying hydrogen to the anode chamber.

[0033] Reference below Figure 1 A simplified flow chart describes the principles of the present application.

[0034] like Figure 1 The restart method or process for a fuel cell system generally includes a shutdown phase P1 of the fuel cell system and a restart phase P2 of the fuel cell system.

[0035] The shutdown phase P1 mainly includes a recording step S1 during the shutdown process of the fuel cell system, which includes a first operation of recording the time when the air supply valve of the air supply subsystem of the fuel cell system is cut off as the shutdown time t1, and a second operation of measuring the gas temperature and pressure in the cathode chamber and the anode chamber respectively.

[0036] The restart phase P2 primarily includes: a start step S2 of the fuel cell system restart process; an optional air measurement step S3; an optional air leakage calculation step S4 during the fuel cell system shutdown period; a determination step S5 for determining whether a purge operation is required for the fuel cell system restart process based on the results of the air measurement step S3 or the air leakage calculation step S4; an optional purge step S6 for performing the purge operation; an end step S7; and an optional hydrogen leakage calculation step Q3. These are described in detail below.

[0037] After the recording step S1 of the shutdown phase P1, the restart method of the present application may further include a shutdown calculation step R1, which includes calculating the remaining air volume M in the cathode chamber and the anode chamber based on the measured gas temperature (the unit of temperature can be: ° C) and pressure (the unit of pressure and pressure difference can be: kPa) in the cathode chamber and the anode chamber respectively. AIR-original and the remaining amount of hydrogen M H-originalAs is known in the art, the gas densities of air and hydrogen in the cathode chamber and the anode chamber can be calculated based on the measured gas temperatures and pressures in the cathode chamber and the anode chamber, and the residual air volume M in the cathode chamber and the anode chamber can be calculated based on the gas densities and the preset volumes of the corresponding chambers. AIR-original and the remaining amount of hydrogen M H-original (The unit of gas amount can be: mol).

[0038] After the shutdown calculation step R1 is completed, the method performs the shutdown state determination step R2: based on the remaining air volume M AIR-original and the remaining amount of hydrogen M H-original Determine whether the remaining gas in the fuel cell stack after the fuel cell system is shut down is air or hydrogen and the remaining gas amount M P1 Afterwards, the method will jump to the starting step S2 of the restart phase P2.

[0039] Optionally, the method may include optional steps after the recording step S1 , in particular after the shutdown calculation step R1 , and before the shutdown state determination step R2 .

[0040] The optional steps may include a first optional step Q1 : detecting whether hydrogen supply valves of hydrogen supply subsystems of the fuel cell system are simultaneously cut off at the shutdown time t1 .

[0041] In the first case, if it is detected in the first optional step Q1 that the hydrogen supply valve and the air supply valve are cut off at the same time, the remaining amount of air M AIR-original and the remaining amount of hydrogen M H-original The method remains unchanged and directly jumps to the shutdown state determination step R2 described above. The simultaneous shutoff of the hydrogen supply valve and the air supply valve may be due to an emergency or unexpected shutdown of the fuel cell system (e.g., a sudden power outage) for any reason, or a normal shutdown (e.g., in response to an operator's operation). In this case, the post-shutdown purge process is not performed.

[0042] Different from the first case, in the second case, if it is detected in the first optional step Q1 that the hydrogen supply valve is not cut off at the same time as the air supply valve, the method executes the update of the remaining hydrogen amount M. H-originalThe second optional step Q2 is as follows. In this case, the air supply valve is first cut off at the shutdown time t1, and the hydrogen supply valve is cut off after a time period (or difference) Δt. The additional hydrogen supplied during the time period Δt is used to consume or purge the remaining air in the fuel cell stack (cathode chamber). In other words, the present method performs a post-shutdown purge process, that is, additional hydrogen is supplied to the anode chamber to react or consume the remaining air in the fuel cell stack. In the second optional step Q2: the time difference between the hydrogen supply valve and the air supply valve being cut off, that is, Δt, is recorded, and the additional amount M of hydrogen supplied within this time difference Δt is calculated based on this time difference Δt and the preset hydrogen supply flow rate. H-additional and add hydrogen with an additional amount M H-additional and the remaining amount of hydrogen M H-original The sum of the updated hydrogen remaining amount M H-original , and at the same time the remaining air volume M AIR-original Maintain unchanged, and then jump to the shutdown state determination step R2.

[0043] As described above, in the shutdown state determination step R2, based on the current remaining air amount M AIR-original and the remaining amount of hydrogen M H-original , determine the remaining air volume M after the fuel cell system is shut down AIR-original The remaining amount of air and hydrogen M H-original After the hydrogen of the two is completely reacted (after the reaction of either one is complete), the remaining gas is air or hydrogen, and the remaining gas amount M (air or hydrogen) is determined P1 As is known in the art, this operation is based on the following reaction formula of hydrogen and oxygen in the air:

[0044] 2H 2+ O2-→2H2O.

[0045] If the remaining amount of hydrogen M is determined based on the reaction equation of hydrogen and oxygen H-original If the fuel cell stack is completely consumed, the remaining gas in the fuel cell stack is considered to be air. The gas amount M P1 Roughly speaking, the remaining amount of air M AIR-original Subtract the remaining amount of hydrogen M H-original The difference in the amount of air reacted, that is, the gas amount M P1 is 0 and the remaining air volume M AIR-original If the air is completely consumed based on the reaction equation of hydrogen and oxygen, the remaining gas in the fuel cell stack is considered to be hydrogen, and the gas amount M P1 The remaining amount of hydrogen M H-original Subtract the remaining air volume M AIR-original The difference in the amount of hydrogen reacted, that is, the gas amount M P1 is 0 and the remaining amount of hydrogen M H-original The value between .

[0046] It is understood that if the shutdown of the fuel cell system is caused by a power outage, the optional steps will not be executed after the recording step S1 of the shutdown phase P1, and the shutdown calculation step R1 and the shutdown state determination step R2 will be executed in the restart phase P2, which can be executed before or after the starting step S2 of the restart phase P2. Therefore, the method of the present application can be set so that the shutdown calculation step R1 and the shutdown state determination step R2 are always executed in the restart phase P2. Optionally, in Figure 1 In the example, the shutdown calculation step R1 and the shutdown state determination step R2 are represented in the shutdown stage P1. At this time, assuming that the fuel cell system is not powered off at the shutdown time t1, although the air supply valve has been cut off, the restart module or the control subsystem is still running. In this case, the optional steps Q1-Q2 can be executed, and the shutdown calculation step R1 and the shutdown state determination step R2 can be executed.

[0047] Optionally, although not shown as a separate step, the method may further include the steps of storing the following measured or calculated data: the data measured or recorded in the recording step S1 (the shutdown time t1, the measured gas temperature and pressure in each chamber), and storing the calculated remaining hydrogen amount M when the shutdown calculation step R1 has been completed. H-original and the remaining air volume M AIR-original , and when the shutdown state determination step R2 has been completed, the result of storing whether the remaining gas in the fuel cell stack after the shutdown process is completed is air or hydrogen, and the remaining gas amount M P1 This storage can be stored in the memory of the restart module or in the memory of the control subsystem.

[0048] The starting step S2 of the restart phase P2 of the present method includes: recording the restart time t2 of the fuel cell system (as defined above), and calculating the shutdown duration t0 based on the shutdown time t1 recorded in the recording step S1 of the shutdown phase P1 and this restart time t2.

[0049] Next, in the first scenario, the shutdown state determination step R2 determines that the remaining gas in the fuel cell stack is air. This indicates that all hydrogen in the fuel cell stack reacted with air during the shutdown of the fuel cell system, and no hydrogen is left inside the fuel cell stack after shutdown. Therefore, at the restart time t2 of the fuel cell system, the gas in the fuel cell stack consists of air and leaked hydrogen. However, since the amount of leakage from the hydrogen supply valve during the shutdown period is very small and negligible, the method of this application assumes that the fuel cell stack, particularly the anode chamber, is entirely filled with air at this time. Therefore, in this case, a purge operation must be performed during the restart process to remove the air from the anode chamber. Based on this, while ignoring the possible hydrogen leakage in the anode chamber, only the amount of gas in the anode chamber needs to be measured, which is used as the amount of air to be removed or consumed by the purge operation. In this case, there is no need to calculate the amount of air leaked into the fuel cell stack during the shutdown period t0. Moreover, assuming that the gas in the anode chamber is entirely air provides a more accurate result than when hydrogen leakage is considered.

[0050] Therefore, when it is determined in the shutdown state determination step R2 that the remaining gas in the fuel cell stack is air, the method performs an air measurement step S3. This step includes measuring the temperature and pressure of the gas in the anode chamber at the restart time t2, and calculating the amount of gas in the anode chamber based on the measured temperature and pressure of the gas in the anode chamber, and determining the calculated amount of gas as the final air amount M. AIR-final , and the final hydrogen volume M H-final The method then jumps to determination step S5.

[0051] In the second case, it is determined in the shutdown state determination step R2 that the remaining gas is hydrogen, indicating that a purge process was performed when the fuel cell system was shut down, assuming that all the air in the fuel cell stack was completely consumed. At this time, at the fuel cell system restart time t2, the gas in the fuel cell stack is the air leaked in from the outside through the air supply valve and the hydrogen remaining after the shutdown process determined in the shutdown state determination step R2 (the hydrogen leaked through the hydrogen supply valve during the shutdown period is still ignored here). Therefore, in this case, the method performs the air leakage calculation step S4 after the start step S2. Theoretically, the air leaked into the fuel cell stack through the air supply valve exists in both the cathode chamber and the anode chamber. For the sake of simplicity and for safety reasons, this application assumes that all leaked air needs to be removed in the purge operation, that is, the air leakage amount M determined in this step is AIR-leak Determined as the final air volume M AIR-final .

[0052] The air leakage calculation step S4 may include calculating the air leakage amount M leaking into the fuel cell stack through the air supply valve during the shutdown period. AIR-leak The first sub-step S41: the air leakage amount M AIR-leak Determined as the final air volume M AIR-final And the remaining gas amount M determined in the shutdown state determination step R2 is P1 Set to the final hydrogen volume M H-final Then, the method jumps to the determination step S5 for determining whether to perform a purge operation.

[0053] Specifically, the first sub-step S41 includes: a first operation of measuring the valve temperature T and the valve internal and external pressure difference ΔP at the air supply valve at the restart time t2; determining the valve leakage rate υ for air during the shutdown period (t0) of the fuel cell system based on the measured valve temperature T and the valve internal and external pressure difference ΔP AIR A second operation based on the air leakage rate v AIR Calculate the air leakage M based on the shutdown time t0 AIR-leak The third operation.

[0054] Theoretically, the valve leakage rate during a fuel cell system shutdown period (t0) is correlated with the valve temperature T and the pressure differential P between the inside and outside of the valve during this shutdown period (t0). However, in practice, the temperature of a device equipped with a fuel cell system (e.g., a fuel cell vehicle) normally experiences little change during the fuel cell system shutdown period (the duration t0 from t1 to t2). Therefore, in the first operation of this method, the valve temperature T measured at the air supply valve when the fuel cell system is restarted (t2) can be used as the valve temperature during the shutdown period (t0). The valve temperature T can be obtained using a temperature sensor located at the corresponding valve.

[0055] Theoretically, the air pressure difference ΔP between the inside and outside of the valve also changes in relation to the valve temperature T. The applicant has found that when the shutdown time t0 of the fuel cell system is long, the pressure difference ΔP between the inside and outside of the valve decreases nonlinearly with the increase of the shutdown time t0 ( Figure 3 ), the relationship between the two can be derived through multiple experiments and fitting the resulting relationship points. However, as mentioned above, if the valve temperature does not change significantly during the fuel cell system shutdown period, the present method can also use the valve internal and external pressure differential measured at the air supply valve when the fuel cell system is restarted (t2) as the valve internal and external pressure differential AP during the shutdown period (t0). The valve internal and external pressure differential AP can be obtained using pressure sensors located on both sides of the corresponding valve.

[0056] In the second operation, based on the valve temperature and the pressure difference between the inside and outside of the valve (measured when the fuel cell system is restarted and used as the pressure difference during the fuel cell system shutdown), the valve leakage rate v for air during the fuel cell system shutdown can be obtained. AIR This can be calculated by using the relationship curve (or function) among the valve leakage rate, the valve temperature and the pressure difference between the inside and outside of the valve, or by querying the corresponding relationship table.

[0057] The pressure difference AP between the inside and outside of the valve and the valve leakage rate v for air AIR It is greatly affected by the design / manufacturing of the valve structure, or by the brand, model, batch, etc. Therefore, the above-mentioned relationship curve (or function) or corresponding relationship table can be provided by the valve supplier (for example, tested and stored before the valve leaves the factory), or obtained by the valve user through experiments on a specific valve. Figure 2 That is, the applicant obtained a series of result points through experiments for an air supply valve of a specific structure, and then obtained a relationship curve by fitting, wherein the relationship curve represents the valve leakage rate υ for air. AIR (ordinate) corresponds to the valve temperature T (first abscissa) and the pressure difference ΔP between the inside and outside of the valve (second abscissa).

[0058] In the third operation, the valve leakage rate v for air is used. AIR The air leakage during the shutdown period M can be calculated by integrating the shutdown time t0 AIR-leak .

[0059] In the second sub-step S42 after the first sub-step S41, the air leakage amount M AIR-leak Determined as the final air volume M AIR-final And the remaining gas amount M determined in the shutdown state determination step R2 is P1 Set to the final hydrogen volume M H-final The method will jump to the determination step S5 for determining whether to perform a purge operation.

[0060] In the determination step S5, based on the final air volume M determined in the air measurement step S3 or in the air leakage calculation step S4 AIR-final and the final hydrogen volume M H-final And whether the restart process needs to execute the purge step S6 is determined based on the reaction formula of hydrogen and oxygen.

[0061] Specifically, the determination step S5 includes a first sub-step S51: calculating the final air quantity M to be completely consumed or reacted (determined in the air measurement step S3 or in the air leakage calculation step S4) AIR-final The desired amount of hydrogen required M H-desiredand compare it with the final hydrogen amount M (determined in the air measurement step S3 or in the air leakage calculation step S4) H-final If the expected amount of hydrogen M is calculated H-desired Less than or equal to the final hydrogen volume M H-final , it means that the hydrogen in the fuel cell stack at the restart time t2 is sufficient to consume the air to be removed (the air in the anode chamber measured and calculated in step S3, and the air leaked into the anode chamber calculated in step S4), and no additional purge operation is required. The method then jumps to step S7 to end the method. H-desired Greater than the final hydrogen volume M H-final , then execute the second sub-step S52: calculate the difference between the two and determine it as the hydrogen demand M H-required This means that the hydrogen present in the fuel cell stack at the restart time t2 or at the beginning of the restart process is not enough to consume the air that needs to be removed - the final air volume M AIR-final , it is necessary to perform the purge step S6 (before the air intake valve can be connected) and the amount of hydrogen required to be supplied in the purge step S6 is M H-required At this point, the method will jump to the purge step S6.

[0062] The purging step S6 includes a first preparation sub-step S61: based on the hydrogen demand M H-required The purge duration is calculated based on the preset hydrogen supply flow rate of hydrogen supplied through the hydrogen supply valve. Thereafter, a second execution sub-step S62 is executed: the hydrogen supply valve of the hydrogen supply subsystem is turned on to supply hydrogen at the preset hydrogen supply flow rate for a duration equal to the purge duration calculated above.

[0063] The purging step S6 of the present method may further include a completing step S63 of automatically connecting an air supply valve of the air supply subsystem to complete the restart process after the second executing substep S62.

[0064] At this point, those skilled in the art can see that the restart method of the fuel cell system of the present application takes into account or calculates the remaining air and hydrogen in the fuel cell stack when the fuel cell system is shut down, and takes into account the air leaked into the fuel cell stack through the air supply valve during the shutdown period. Based on the above two, through accurate calculation, it is determined whether there is air in the fuel cell stack or its anode chamber when the fuel cell system is restarted, and whether a purge operation is required during the restart process. When it is determined that a purge operation is to be performed, this method also accurately calculates the amount of hydrogen required for the purge operation (or the amount required in addition to the hydrogen remaining at the time of shutdown), thereby avoiding excessive hydrogen supply during the purge operation, which would cause waste.

[0065] As can be seen, the present application also has the advantage of not performing a purge operation when the calculation results indicate that the hydrogen in the fuel cell stack is sufficient to consume the air in the fuel cells during restart of the fuel cell system. This not only simplifies and speeds up the restart process, but also avoids unnecessary hydrogen supply and waste, as mentioned above.

[0066] In the above description, hydrogen leakage is not considered because the amount of hydrogen leakage during the shutdown of the fuel cell system is very small. The present application also provides a more precise implementation method. The restart phase P2 of the restart method of the present application may also include a hydrogen leakage calculation step Q3.

[0067] Similar to the air leakage calculation step S4, the hydrogen leakage calculation step Q3 may include a first calculation sub-step Q31: an operation of measuring the valve temperature and the pressure difference between the inside and outside of the valve at the hydrogen supply valve at the restart time t2; an operation of calculating the valve leakage rate for hydrogen during the shutdown period of the fuel cell system based on the measured valve temperature and the pressure difference between the inside and outside of the valve; and an operation of calculating the hydrogen leakage amount M based on the valve leakage rate for hydrogen and the shutdown duration. H-leak operation.

[0068] These operations differ from the operations of air leakage calculation step S4 only in that the curves (or functions) or corresponding tables for the relationship between valve leakage rate, valve temperature, and pressure differential between inside and outside the valve for hydrogen and air may differ. All other operations are identical and will not be described in detail here.

[0069] The hydrogen leakage calculation step Q3 finally includes an update sub-step Q32: using the current final hydrogen amount M H-final The calculated hydrogen leakage M H-leak The final hydrogen amount M is updated by the sum parameter H-final Afterwards, the method returns to the first sub-step S51 of the determination step S5.

[0070] The hydrogen leakage calculation step Q3 can be performed after the air measurement step S3 or the air leakage calculation step S4. After the hydrogen leakage calculation step Q3 is performed, the calculation result of the restart method is more accurate.

[0071] Reference attached above Figure 1 The restart method of the fuel cell system of the present application is described. The method may also include a storage step for storing various original or intermediate data measured and calculated during the execution of the restart method. Storing these data can provide reference materials for upgrading and optimizing the fuel cell system.

[0072] The present application also provides a restart module for executing the restart method of the fuel cell system described above. The restart module may include a measuring unit, a memory, and a processor of the measuring sensors used to execute the various steps of the above method. The measuring unit includes a first and a second gas temperature sensor for measuring the gas temperature of the cathode chamber and the anode chamber of the fuel cell stack, a first and a second gas pressure sensor for measuring the gas pressure of the cathode chamber and the anode chamber of the fuel cell stack, a first valve temperature sensor for measuring the temperature at the air supply valve, an optional second valve temperature sensor for measuring the temperature at the hydrogen supply valve, a valve pressure sensor for measuring the inner and outer pressures at the air supply valve to obtain the inner and outer pressure difference, and a valve pressure sensor for measuring the inner and outer pressures at the hydrogen supply valve to obtain the inner and outer pressure difference, etc.

[0073] The memory may be used to store various raw or intermediate data measured and calculated during the execution of the restart method; a curve or lookup table showing the relationship between the valve leakage rate for air, valve temperature, and valve internal and external pressure differential of the air supply valve, a curve or lookup table showing the relationship between the valve leakage rate for hydrogen, valve temperature, and valve internal and external pressure differential of the hydrogen supply valve, etc.; various calculation formulas used during the execution of the restart method, etc. The processor may store executable instructions that, when executed by the processor, can execute the restart method described above.

[0074] The present application also provides a machine (or computer) readable storage medium storing executable instructions, which implement the restart method described above when executed by a processor.

[0075] The principle of the present application and some embodiments for realizing this principle are described in detail above. It should be understood by those skilled in the art that the present application is not limited to the embodiments shown in the drawings and described above. Without departing from the principle and essence of the present application, each embodiment of the present application and its details can be modified, and the modifications are considered to fall within the protection scope of the present application.

Claims

1. A method for restarting a fuel cell system, the fuel cell system comprising a fuel cell stack having a cathode chamber and an anode chamber, an air supply subsystem communicating with the cathode chamber and having an air supply valve, and a hydrogen supply subsystem communicating with the anode chamber and having a hydrogen supply valve, the method comprising: a recording step (S1) of recording the downtime (t1) when the air supply valve is cut off and measuring the temperature and pressure of the gas in the cathode chamber and the anode chamber respectively; The remaining amount of air (M) in the cathode chamber and the anode chamber is calculated based on the gas temperature and pressure in the cathode chamber and the anode chamber measured in the recording step (S1). AIR-original ) and the remaining amount of hydrogen (M H-original )’s shutdown calculation step (R1); Based on the remaining air volume (M AIR-original ) and the remaining amount of hydrogen (M H-original ) Determine whether the remaining gas in the fuel cell stack after the fuel cell system is shut down is air or hydrogen and the remaining gas amount (M P1 ) of the shutdown state determination step (R2); a starting step (S2) of recording a restart time (t2) of the fuel cell system and calculating a shutdown duration (t0) based on the shutdown time (t1) and the restart time (t2); When it is determined in the shutdown state determination step (R2) that the remaining gas is air, the following steps are performed: determining the amount of air contained in the anode chamber at the restart time (t2) and determining it as the final air amount (M AIR-final ) and the final hydrogen volume (M H-final ) determining the air measurement step (S3) of 0; If it is determined in the shutdown state determination step (R2) that the remaining gas is hydrogen, the following steps are performed: determining the amount of air leakage (M) leaking into the fuel cell stack through the air supply valve during shutdown; AIR-leak ) and determine it as the final air volume (M AIR-final ) and the final hydrogen volume (M H-final ) is determined as the gas amount (M) determined in the shutdown state determination step (R2) P1 ) air leakage calculation step (S4); Based on the final air volume (M) determined in the air measurement step (S3) or the air leakage calculation step (S4), AIR-final ) and the final hydrogen volume (M H-final ) executing: determining whether a purge operation needs to be performed during the restart process (S5); and If it is determined in the determining step ( S5 ) that the purge operation needs to be performed, a purge step ( S6 ) of calculating the amount of hydrogen gas to be supplied in the purge operation and performing the purge operation is performed.

2. The restart method according to claim 1, wherein: Also includes: After the shutdown calculation step (R1) and before the shutdown state determination step (R2), a first optional step (Q1) is performed to detect whether the hydrogen supply valve is shut off at the shutdown time (t1).

3. The restart method according to claim 2, wherein: Also includes: When it is detected that the hydrogen supply valve is cut off during the shutdown time (t1), executing the shutdown state determination step (R2); and In the case where it is detected that the hydrogen supply valve is not cut off during the shutdown time (t1), a second optional step (Q2) is performed: recording the time difference (Δt) between when the hydrogen supply valve and the air supply valve are cut off, and calculating the additional amount of hydrogen (M) supplied during the time difference (Δt). H-additional ), and the additional amount of hydrogen (M H-additional ) and the remaining amount of hydrogen (M H-original ) and update the remaining hydrogen amount (M H-original ).

4. The restart method according to any one of claims 1 to 3, wherein: In the air measuring step (S3), the temperature and pressure of the gas in the anode chamber at the restart time (t2) are measured, and the amount of the gas in the anode chamber is calculated based on the measured temperature and pressure of the gas in the anode chamber, which is determined as the final air amount (M AIR-final ).

5. The restart method according to any one of claims 1 to 4, wherein: The air leakage calculation step (S4) includes: a first operation of measuring a valve temperature (T) and a pressure difference between an inner side and an outer side of the valve (ΔP) at the air supply valve at the restart time (t2); and determining a valve leakage rate (υ) for air during the shutdown period of the fuel cell system based on the measured valve temperature (T) and the pressure difference between an inner side and an outer side of the valve (ΔP). AIR ) of the second operation; based on the valve leakage rate and downtime for air (t0) calculate the air leakage (M AIR-leak ) of the third operation; the air leakage (M AIR-leak ) is determined as the final air volume (M AIR-final )’s fourth operation.

6. The restart method according to claim 5, wherein: The second operation is performed based on a relationship curve or a corresponding relationship table of the valve leakage rate for air, the valve temperature, and the pressure difference between the inside and outside of the valve.

7. The restart method according to claim 6, wherein: The relationship curve or corresponding relationship table is provided by the supplier of the air supply valve or obtained through experiments.

8. The restart method according to any one of claims 1 to 7, wherein: The determining step (S5) includes: calculating the final air volume (M AIR-final ) The desired amount of hydrogen required for the reaction (M H-desired ) and the final amount of hydrogen (M H-final ) compared; and the expected amount of hydrogen (M H-desired ) is greater than the final hydrogen amount (M H-final ) to determine the need for a purge operation and calculate the difference between the two to determine it as the hydrogen demand (M H-required ), and in the desired hydrogen amount (M H-desired ) is less than or equal to the final hydrogen volume (M H-final ) ends this method.

9. The restart method according to claim 8, wherein: The purging operation (S6) includes: based on the hydrogen demand (M H-required ) and a preset hydrogen supply flow rate to calculate the purge duration; and turning on the hydrogen supply valve to supply hydrogen at the preset hydrogen supply flow rate for a duration equal to the purge duration.

10. The restart method according to claim 9, wherein: The purging operation (S6) further includes automatically turning on the air intake valve after the hydrogen is supplied for the purging time.

11. The restart method according to any one of claims 1 to 10, further comprising a hydrogen leakage calculation step (Q3) after the air measurement step (S3) or the air leakage calculation step (S4) and before the determination step (S5), comprising: At the restart time (t2), the valve temperature and the pressure difference between the inside and outside of the valve are measured at the hydrogen supply valve; the valve leakage rate for hydrogen during the shutdown period of the fuel cell system is determined based on the measured valve temperature and the pressure difference between the inside and outside of the valve; the hydrogen leakage amount (M) is calculated based on the valve leakage rate for hydrogen and the shutdown time. H-leak ); and using the final hydrogen amount (M H-final ) and the hydrogen leakage (M H-leak ) and update the final hydrogen volume (M H-final ).

12. A restart module for a fuel cell system, the restart module comprising a processor storing executable instructions, wherein the executable instructions, when executed by the processor, perform the restart method according to any one of claims 1 to 11. 13 . A control subsystem for a fuel cell system, comprising the restart module for a fuel cell system according to claim 12 .

14. A fuel cell system comprising: A fuel cell stack having a cathode chamber and an anode chamber, an air supply subsystem communicating with the cathode chamber and having an air supply valve, and a hydrogen supply subsystem communicating with the anode chamber and having a hydrogen supply valve; And, the restart module for a fuel cell system according to claim 12 or the control subsystem for a fuel cell system according to claim 13. 15 . A machine-readable storage medium comprising a processor storing executable instructions, wherein the executable instructions, when executed by the processor, perform the restart method according to claim 1 .

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