Fuel cell system and cold start control method and control device therefor

Abstract

The present application discloses a control device for controlling cold starting of a fuel cell system. The fuel cell system comprises a stack, a load and a cooling loop; the stack comprises an electrode plate and a membrane electrode assembly; and the control device comprises: a measurement module, configured to measure an initial temperature T0 of the stack; a calculation module, configured to calculate an internal temperature T of the stack on the basis of the initial temperature T0 and the output current I and the output voltage U outputted from the stack to a load; a determination module, configured to compare the calculated internal temperature T with a threshold temperature Tth; and an adjustment module, configured to, when the internal temperature T is greater than the threshold temperature Tth, increase the flow volume Qcoolant of a coolant in a cooling circuit flowing through the stack. The present application further discloses a fuel cell system comprising the control device, a control method for the fuel cell system and a computer readable storage medium. The present application can realize rapid and safe cold starting of the fuel cell system.

Description

Fuel cell system and cold start control method and control device thereof Technical Field

[0001] The present application relates to the field of fuel cell technology, and in particular to a control method and a control device for controlling a cold start of a fuel cell, and a fuel cell system including the control device. Background Art

[0002] With the development of fuel cell technology, the use of fuel cells as power supply devices has gained increasing attention. For example, proton exchange membrane fuel cells (PEMFCs) have gradually become one of the main power sources for new energy vehicles due to their high energy efficiency and zero pollution.

[0003] A proton exchange membrane fuel cell typically consists of a fuel cell stack, a hydrogen supply, an oxygen (or air) supply, and a power output device. During operation, hydrogen and oxygen supplied to the fuel cell stack react electrochemically under the action of a catalyst, generating water and releasing electrons, which can then be used to output electricity (for example, to power a vehicle's drive motor).

[0004] Because water is generated in the fuel cell stack, it can freeze inside the stack (and even inside the membrane electrode assembly) after shutdown in subfreezing temperatures. This ice not only blocks the gas transmission path during a cold start of the fuel cell, causing startup difficulties, but also damages the microstructure of the membrane electrode assembly, shortening the lifespan of the fuel cell stack. To mitigate ice formation within the fuel cell stack, a purge is typically performed before shutdown to minimize water in the stack. However, some water inevitably remains in the stack, and even at low temperatures, ice can form, leading to cold start difficulties.

[0005] In order to solve the problem of difficult cold start of fuel cells, the existing technology usually uses the heat generated inside the stack or an external heater to heat the stack, so that the temperature of the stack can be raised to the operating temperature as quickly as possible to achieve a smooth start. Since the cooling circuit is required to take away the heat generated by the stack during normal operation of the fuel cell, the cooling circuit will also take away the heat provided by the internal or external heater of the stack during the cold start process, resulting in a long cold start time. Therefore, in order to achieve a fast cold start, the existing technology proposes a technical solution of using a smaller cooling circuit during the cold start to reduce the volume of the coolant and use as much of the heat generated inside the stack as possible for heating. Despite this, the intervention of the coolant will also greatly increase the thermal capacity of the stack, making the heating process of the stack and the cold start process longer.

[0006] To further shorten the cold start time, existing techniques propose stopping the coolant supply during a cold start to retain heat generated within the stack and allow it to heat up quickly. However, this carries the risk of stack overheating, as the actual temperature inside the stack is unknown. Excessive stack temperatures can cause the proton exchange membrane to dry out, losing its ability to conduct protons and making it susceptible to rupture, causing permanent damage to the stack.

[0007] Therefore, cold start has become a major issue for proton exchange membrane fuel cells, but there is still no feasible technical solution to this problem in the existing technology. It should be noted that in addition to proton exchange membrane fuel cells, fuel cells using other fuels (such as ammonia, coal gas, natural gas, biomass gas, etc.) also have similar problems as long as water is generated in the stack.

[0008] Therefore, it is necessary to improve the existing fuel cell system and its cold start control method and control device.

[0009] Summary of the Invention

[0010] The purpose of the present application is to provide a fuel cell system and a cold start control method and control device thereof to overcome at least one of the above-mentioned technical problems.

[0011] To this end, according to one aspect of the present application, a control device for controlling the cold start of a fuel cell system is provided, wherein the fuel cell system includes a fuel cell stack, a load, and a cooling circuit, wherein the fuel cell stack includes a plate and a membrane electrode assembly, and the control device includes: a detection module configured to detect an initial temperature T0 of the fuel cell stack; a calculation module configured to calculate an internal temperature T of the fuel cell stack based on the initial temperature T0 and an output current I and an output voltage U output from the fuel cell stack to the load; and a judgment module configured to compare the calculated internal temperature T with a threshold temperature T th Comparison; an adjustment module configured to adjust the internal temperature T when it is greater than the threshold temperature T th In the case of increasing the flow rate Q of the coolant flowing through the stack in the cooling circuit coolant .

[0012] According to another aspect of the present application, a control method for controlling a cold start of a fuel cell system is provided, wherein the fuel cell system includes a stack, a load, and a cooling circuit, wherein the stack includes a plate and a membrane electrode assembly, and the control method includes: a detection step, in which an initial temperature T0 of the stack is detected; a calculation step, in which an internal temperature T of the stack is calculated based on the initial temperature T0 and an output current I and an output voltage U output from the stack to the load; a temperature judgment step, in which the calculated internal temperature T is compared with a threshold temperature T th Compare; a first flow adjustment step, in which the internal temperature T is greater than the threshold temperature T th In the case of increasing the flow rate Q of the coolant flowing through the stack in the cooling circuit coolant .

[0013] According to another aspect of the present application, a fuel cell system is provided, comprising: a fuel cell stack; a first gas supply device configured to supply a first gas to the fuel cell stack; a second gas supply device configured to supply a second gas to the fuel cell stack; a cooling circuit configured to allow a coolant to flow through the fuel cell stack; and the control device described above, wherein the control device is configured to control the cold start of the fuel cell system.

[0014] According to another aspect of the present application, a computer-readable storage medium is provided, on which computer instructions are stored. When the computer instructions are executed by one or more processors, the one or more processors are caused to execute the steps of the control method described above.

[0015] The fuel cell system and its cold start control method and control device of the present application can make full use of the heat generated inside the fuel cell stack to heat up the fuel cell stack, and the internal temperature of the fuel cell stack and the degree of dehydration of the membrane electrode assembly can be effectively monitored, and coordinated with the supply of coolant in the cooling circuit, while quickly heating up, avoiding overheating and overdrying, thereby achieving a fast and safe cold start. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The exemplary embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the embodiments described below are only used to explain the present application, rather than to limit the scope of the present application. In the accompanying drawings:

[0017] FIG1 schematically shows a structural block diagram of a fuel cell system according to an embodiment of the present application;

[0018] FIG2 schematically shows a block diagram of a control device for controlling a cold start of a fuel cell system;

[0019] FIG3 schematically shows a graph of the internal temperature and high-frequency resistance of the stack changing with time;

[0020] FIG4 schematically shows a schematic flow chart of a control method for controlling a cold start of a fuel cell system according to an embodiment of the present application. DETAILED DESCRIPTION

[0021] The preferred embodiments of the present application are described in detail below with reference to examples. In the embodiments of the present application, a proton exchange membrane fuel cell system and its cold start control method and control device are used as examples to describe the present application. However, those skilled in the art should understand that these exemplary embodiments are not intended to limit the present application in any way. For example, the control method and control device of the present application can also be used to control the cold start of a fuel cell system using other gases as fuel, as described above.

[0022] In addition, the features of the embodiments of the present application may be combined with each other unless they conflict. In different figures, identical components are denoted by identical reference numerals, and other components are omitted for simplicity. This does not imply that the fuel cell system and control device of the present application cannot include other components, nor does it imply that the control method of the present application cannot include other steps. It should be understood that the dimensions, proportional relationships, number of components, and order of steps in the drawings are not intended to limit the present application.

[0023] The overall structure of a fuel cell system 200 according to an embodiment of the present application is described below with reference to FIG1 . As shown in FIG1 , the fuel cell system 200 includes a fuel cell stack 210 , a first gas supply device 220 , a second gas supply device 230 , a load 240 , a cooling circuit 260 , and a control device 100 .

[0024] The battery stack 210 may include at least one battery cell (i.e., a unit cell), and each battery cell may include a plate (e.g., a monopolar plate or a bipolar plate) and a membrane electrode assembly (e.g., a proton exchange membrane). Since the internal structure of the battery stack 210 is not improved in the present application, the internal structure of the battery stack 210 is not described in more detail herein, and the internal structure of the battery stack 210 is not shown in the accompanying drawings. It should be understood that, in this article, the plates and membrane electrode assembly of the battery stack 210 refer to the set of plates and membrane electrode assemblies of each battery cell contained in the battery stack 210. However, the present application is not limited to this, and the technical principles of the present application also apply to each battery cell, that is, each battery cell in the battery stack 210 is regarded as a small battery stack. Therefore, in the following, the battery cells are no longer described separately, but the technical solution of the present application is described for the battery stack 210 as a whole.

[0025] The first gas supply device 220 is configured to supply the first gas to the fuel cell stack 210. As shown in Figure 1, the first gas enters the fuel cell stack 210 from the first gas inlet (not shown) and is discharged from the first gas outlet (not shown), as indicated by the arrows. In a proton exchange membrane fuel cell system, the first gas can be hydrogen, but the present application is not limited thereto. For example, the first gas can also be other fuel gases such as ammonia and coal gas.

[0026] The second gas supply device 230 is configured to supply the second gas to the fuel cell stack 210. As shown in Figure 1, the second gas enters from the second gas inlet (not shown) of the fuel cell stack 210 and is discharged from the second gas outlet (not shown), as shown by the arrows. In the proton exchange membrane fuel cell system, the second gas can be oxygen or air, but the present application is not limited thereto. For example, according to the change of the first gas as the fuel gas, the type of the second gas is changed accordingly.

[0027] The load 240 may be, for example, a DC / DC converter, which converts the power output by the fuel cell stack 210 into a higher or lower voltage for storage in a battery or for use by electrical appliances.

[0028] Cooling circuit 260 is configured to allow coolant to flow through fuel cell stack 210 to remove heat released during operation of fuel cell stack 210, thereby maintaining a suitable operating temperature for fuel cell stack 210 and preventing damage to, for example, the membrane electrode assembly within fuel cell stack 210 due to excessive temperature. As shown in FIG1 , coolant in cooling circuit 260 enters fuel cell stack 210 from a coolant inlet (not shown) of fuel cell stack 210 via pump 263 and then flows out from a coolant outlet (not shown) of fuel cell stack 210, as indicated by the arrows.

[0029] In addition, in order to detect the temperatures of the first gas, the second gas, and the coolant when entering the fuel cell stack 210 and when being discharged from the fuel cell stack 210, the fuel cell system 200 may further include: a first gas inlet thermometer 221, which is configured to detect the first gas inlet temperature T of the first gas entering the fuel cell stack 210. 1in A first gas outlet thermometer 222 configured to detect the first gas outlet temperature T of the first gas discharged from the stack 210 1out A second gas inlet thermometer 231 configured to detect the second gas inlet temperature T of the second gas entering the stack 210 2in A second gas outlet thermometer 232 configured to detect the second gas outlet temperature T of the second gas discharged from the stack 210 2out ; Coolant inlet thermometer 261, which is configured to detect the coolant inlet temperature T of the coolant entering the stack 210 coolantin and a coolant outlet thermometer 262 configured to detect the coolant outlet temperature T of the coolant discharged from the stack 210coolantout The various thermometers mentioned above are only examples. Depending on the changes in the parameters to be detected, more or fewer thermometers or other devices for detecting temperature may be provided.

[0030] The control device 100 is configured to control a cold start of the fuel cell system 200. It should be noted that, for simplicity, FIG1 shows only the coolant inlet thermometer 261 and the coolant outlet thermometer 262 connected to the control device 100, while the first gas inlet thermometer 221, the first gas outlet thermometer 222, the second gas inlet thermometer 231, and the second gas outlet thermometer 232 are not shown connected to the control device 100. However, in practice, these thermometers are also connected to the control device 100, for example, by wire or wireless means.

[0031] The control device 100 is described in more detail below with reference to Figure 2. As shown in Figure 2, the control device 100 may include a detection module 10, a calculation module 20, a judgment module 30, an adjustment module 40, a measurement module 50, and an output module 60, but the present application is not limited thereto and may include more or fewer modules.

[0032] The detection module 10 may be configured to detect the initial temperature T0 of the fuel cell stack 210. The initial temperature T0 may be the ambient temperature of the fuel cell system 200. In particular, in a low temperature environment, the initial temperature T0 may be below freezing. The detection module 10 may also be configured to detect the coolant inlet temperature T0 of the coolant entering the fuel cell stack 210. coolantin and the coolant outlet temperature T of the coolant discharged from the stack 210 coolantout In addition, the detection module 10 can also be configured to detect the first gas inlet temperature T of the first gas entering the fuel cell stack 210. 1in and the first gas outlet temperature T of the first gas discharged from the fuel cell stack 210 1out , and detecting the second gas inlet temperature T of the second gas entering the fuel cell stack 210 2in and the second gas outlet temperature T of the second gas discharged from the fuel cell stack 210 2out It should be understood that the detection module 10 can also be configured to detect various parameters, variables or characteristic values ​​of the stack 210, the first gas, the second gas and the coolant, for example, to detect the flow rate Q1 of the first gas, the flow rate Q2 of the second gas and the flow rate Q coolant .

[0033] The calculation module 20 can be configured to calculate the internal temperature T of the fuel cell stack 210 based on the initial temperature T0 of the fuel cell stack 210 and the output current I and output voltage U output from the fuel cell stack 210 to the load 240. This application proposes a technical concept for calculating the internal temperature T of the fuel cell stack 210, so that the internal temperature T of the fuel cell stack 210 can be monitored at any time to ensure that the cold start of the fuel cell system 200 can be carried out safely and quickly.

[0034] Specifically, the internal heat of the stack 210 is absorbed by the plates, the membrane electrode assembly, and the coolant in the cooling chamber of the stack 210, thereby causing the internal temperature of the stack 210 to rise. The calculation module 20 can calculate the internal temperature T based on the following formula (1):

[0035] The internal heat of the stack 210 is W, which is calculated by subtracting the heat dissipated from the stack 210 from the heat generated in the stack 210. The heat generated in the stack 210 is W1, W1 = I*(E0-U), E0 is the reversible voltage in the stack 210, C BPP 、C MEA and C coolant are the specific heat capacities of the plate, membrane electrode assembly and coolant, respectively, m BPP and m MEA are the masses of the plates and membrane electrode assemblies, ρ coolant is the density of the coolant, V coolant-chamber is the volume of the coolant present in the cooling cavity of the fuel cell stack 210, which corresponds to the volume of the cooling cavity. When the heat dissipated from the fuel cell stack 210 is ignored, W=W1. Therefore, the present application provides a feasible solution for estimating the internal temperature of the fuel cell stack 210. It should be noted that the internal temperature of the fuel cell stack 210 estimated when the heat dissipated from the fuel cell stack 210 is ignored can be corrected by an appropriate coefficient (which can be obtained by experimental calibration or simulation). In this case, an estimated value of the internal temperature of the fuel cell stack 210 can still be reliably provided, while the configuration and calculation can be simplified.

[0036] It should be noted that C BPP 、C MEA 、C coolant 、m BPP 、m MEA , ρ coolant and V coolant-chamber are the physical properties of the corresponding components, and their specific values ​​can be determined in advance during the manufacturing process of fuel cell system 200. Furthermore, the reversible voltage E0 of fuel cell stack 210 can be calculated using the Nernst equation. Since the method for calculating the reversible voltage E0 is well known in the art, it will not be further described herein.

[0037] It should be noted that if the coolant supply is stopped when the fuel cell system 200 is cold-started, the coolant flow rate Q coolant is zero.

[0038] The internal temperature T of the fuel cell stack 210 can be estimated using the above formula (1).

[0039] The judgment module 30 may be configured to compare the calculated internal temperature T with the threshold temperature T th Here, the threshold temperature T th It can refer to the upper limit temperature of the normal operation of the stack 210. For example, the threshold temperature T th It can be obtained through experimental calibration or simulation. When the internal temperature T exceeds the threshold temperature T th If a stronger cooling is not performed, the stack 210 may be overheated and damaged. As shown in FIG3 , during the cold start process of the fuel cell system 200, as time t changes, the internal temperature T gradually increases. When it is greater than the threshold temperature T th When the coolant flow rate Q is increased, coolant .

[0040] Therefore, the adjustment module 40 is configured to adjust the temperature when the internal temperature T is greater than the threshold temperature T th In the case of increasing the flow rate Q of the coolant flowing through the fuel cell stack 210 in the cooling circuit 260 coolant If no coolant was supplied during the previous startup, the coolant flow rate Q coolant Starts at 0 and increases in set increments.

[0041] As the startup process proceeds, the judgment module 30 is further configured to judge the coolant flow rate Q coolant Is it increased to be greater than the first predetermined flow rate u1, wherein the first predetermined flow rate u1 is associated with the target power of the pump 263 for pumping the coolant. That is, the first predetermined flow rate u1 corresponds to the target power of the pump 263. When the adjustment module 40 attempts to increase the coolant flow rate Q coolant When the flow rate increases to be greater than the first predetermined flow rate u1 , the pump 263 will be required to output a power greater than the target power, which is detrimental to the safe operation of the pump 263 .

[0042] Therefore, the output module 60 of the control device 100 can be configured to coolant When the flow rate exceeds the first predetermined flow rate u1, an emergency shutdown message is output. The output module 60 can be a display, speaker, etc., to output text, images, or audio information. While outputting the emergency shutdown message, the control device 100 can also execute an emergency shutdown procedure to stop the cold start process of the fuel cell system 200.

[0043] Therefore, according to the above-described embodiment of the present application, under the control of the control device 100, the heat generated within the fuel cell stack 210 can be fully utilized to quickly heat the fuel cell stack 210, and the internal temperature of the fuel cell stack 210 can be effectively monitored. In addition, when the internal temperature T is detected to be too high, the supply of coolant can be coordinated to achieve a rapid and safe cold start.

[0044] Furthermore, when heat is generated in the stack 210, part of the heat will be taken away by the flowing coolant, resulting in part of the heat being lost from the stack 210 through the coolant. When it is necessary to monitor the internal temperature T of the stack 210 more accurately, the calculation module 20 may also calculate the internal temperature T of the stack 210 based on the coolant inlet temperature T. coolantin and coolant outlet temperature T coolantout To calculate the heat W2 dissipated from the stack 210 through the coolant, W2 = C coolant *ρ coolant *Q coolant *(T coolantout -T coolantin ). Therefore, when further considering the heat W2 dissipated from the stack 210 through the coolant, W=W1-W2. In this case, the calculation module 20 can calculate the internal temperature T based on the following formula (2):

[0045] If coolant is supplied at an initial flow rate u0 during a cold start of the fuel cell system 200, the flowing coolant removes some heat from the fuel cell stack 210. The heat removed by the flowing coolant can be taken into account using the above formula (2), thereby allowing a more accurate estimation of the internal temperature T of the fuel cell stack 210.

[0046] Although the first gas and the second gas undergo electrochemical reactions in the fuel cell stack 210 and are consumed, a portion of the gas is not consumed and is discharged from the fuel cell stack 210, thus taking away a portion of heat from the fuel cell stack 210, causing a portion of heat to be dissipated from the fuel cell stack 210 through the first gas and the second gas. In order to take into account the heat taken away from the fuel cell stack 210 by the first gas and the second gas, the calculation module 20 may further calculate the heat based on the first gas inlet temperature T 1in , first gas outlet temperature T 1out , Second gas inlet temperature T 2in and the second gas outlet temperature T 2out Calculate the heat W3 dissipated from the fuel cell stack 210 through the first gas, W3 = C1*ρ1*Q1*(T 1out -T 1in ), C1 is the specific heat capacity of the first gas, ρ1 and Q1 are the density and flow rate of the first gas respectively; and the heat W4 dissipated from the stack 210 through the second gas, W4=C2*ρ2*Q2*(T2out -T 2in ), C2 is the specific heat capacity of the second gas, and ρ2 and Q2 are the density and flow rate of the second gas, respectively. Therefore, considering the heat W3 and W4 dissipated from the stack 210 by the first and second gases, respectively, W = W1 - W2 - W3 - W4. In this case, the calculation module 20 can calculate the internal temperature T based on the following formula (3):

[0047] The above formula (3) can further take into account the heat dissipated from the fuel cell stack 210 through the coolant, the first gas, and the second gas, thereby estimating a more accurate internal temperature T of the fuel cell stack 210 .

[0048] Although there may be a difference between the flow rate of each of the first gas and the second gas entering the fuel cell stack 210 and the flow rate discharged from the fuel cell stack 210, to simplify the calculation process, the flow rate of each of the first gas and the second gas can be set to the flow rate entering the fuel cell stack 210. Of course, the flow rate of each of the first gas and the second gas can also be set to the flow rate discharged from the fuel cell stack 210, or the average of the flow rate entering the fuel cell stack 210 and the flow rate discharged from the fuel cell stack 210, and the technical concept of the present application still applies.

[0049] As is known in the art, the membrane electrode assembly in the stack 210 needs to maintain a certain degree of wetness (water content) to facilitate the electrochemical reaction. During the startup process of the fuel cell system 200, as the internal temperature T of the stack 210 increases, the membrane electrode assembly (especially the proton exchange membrane) is easily dehydrated and membrane drying occurs. When membrane drying occurs, the membrane electrode assembly will become dry, resulting in a decrease in proton conductivity, a significant weakening of the conductive performance, and a decrease in the output voltage. That is to say, within a certain range, as the water content of the membrane electrode assembly decreases, the internal impedance of the stack 210 gradually increases. When the membrane electrode assembly is in a severely dry state for a long time, it may cause irreversible damage to the membrane electrode assembly.

[0050] Therefore, in order to ensure the safe cold start process of the fuel cell system 200, the present application also takes into account the changes in the internal impedance of the stack 210 during the cold start process. The internal impedance of the stack 210 can be obtained by electrochemical impedance spectroscopy testing. Specifically, a high-frequency AC excitation signal can be applied to the stack 210, and then the impedance response can be recorded to calculate the internal impedance. Since the resistance value measured by the high-frequency AC excitation signal in the test is related to the resistance value of the membrane electrode assembly, the high-frequency resistance HFR (High Frequency Resistance) is used in this application to monitor the degree of dehydration of the membrane electrode assembly. It should be pointed out that the measurement of the high-frequency resistance HFR is not limited to the above-mentioned method, but can also adopt any feasible method known in the art, which will not be further described herein.

[0051] As shown in FIG3 , during the cold start process of the fuel cell system 200, the high-frequency resistance HFR may increase as the internal temperature T of the stack 210 increases until it increases to a critical value, i.e., the first resistance threshold ε1. Therefore, according to an embodiment of the present application, after measuring the high-frequency resistance HFR, the judgment module 30 may compare the high-frequency resistance HFR with the first resistance threshold ε1. If the high-frequency resistance HFR is greater than the first resistance threshold ε1, the output module 60 outputs an emergency shutdown message. While outputting the emergency shutdown message, the control device 100 may also execute an emergency shutdown step to stop the cold start process of the fuel cell system 200 to avoid damaging the stack 210.

[0052] Furthermore, in order to alert the user when the membrane electrode assembly has experienced a certain degree of dehydration but has not yet reached a critical state, the judgment module 30 may also compare the high-frequency resistance HFR with the second resistance threshold ε2, wherein the second resistance threshold ε2 is less than the first resistance threshold ε1, as shown in FIG3. In this case, the output module 60 may issue an alarm message when the high-frequency resistance HFR is greater than the second resistance threshold ε2. At this time, in order to slow down the dehydration of the membrane electrode assembly, the adjustment module 40 may adjust the coolant flow rate Q coolant Increase to be greater than the second predetermined flow rate u2. In this way, when the membrane electrode assembly is dehydrated to a certain extent, an alarm can be given to the user, and the flow rate of the coolant can be adjusted to prevent the dehydration from worsening.

[0053] Furthermore, in order to warn the user when the membrane electrode assembly is just beginning to dehydrate, the judgment module 30 is further configured to compare the high-frequency resistance HFR with a third resistance threshold ε3, where the third resistance threshold ε3 is less than the second resistance threshold ε2, as shown in FIG3 . In this case, the output module 60 may output a warning message when the high-frequency resistance HFR is greater than the third resistance threshold ε3. At this time, in order to prevent the membrane electrode assembly from dehydrating further, the adjustment module 40 may adjust the coolant flow rate Qcoolant The flow rate increases to be greater than the third predetermined flow rate u3, which is less than the second predetermined flow rate u2. In this way, the user can be alerted when the membrane electrode assembly just begins to dehydrate, and the dehydration can be slowed down by adjusting the coolant flow rate.

[0054] It should be noted that in the above embodiment, the first resistance threshold ε1, the second resistance threshold ε2, the third resistance threshold ε3, the second predetermined flow rate u2 and the third predetermined flow rate u2 can be obtained through experimental calibration or simulation, and can be pre-stored in the storage device of the control device 100.

[0055] Therefore, according to the above embodiment of the present application, under the control of the control device 100, the dehydration degree of the membrane electrode assembly of the stack 210 (corresponding to the high-frequency resistance HFR of the stack 210) can be monitored at any time. When a predetermined change in the high-frequency resistance HFR is detected, the flow rate Q of the coolant can be appropriately adjusted. coolant , ensuring that the membrane electrode assembly is not damaged during the cold start process.

[0056] It should be noted that all or some of the modules of the control device disclosed above may be implemented as software, firmware, hardware, or any suitable combination thereof. Some or all of the modules may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or as an integrated circuit, such as an application-specific integrated circuit, a field-programmable gate array, or the like. For example, the control device 100 may be the control unit of the fuel cell system 200 or one or more modules thereof, or may be part of the electronic control unit of a vehicle in which the fuel cell system 200 is installed.

[0057] A control method for controlling a cold start of a fuel cell system according to an embodiment of the present application will be described in detail below with reference to FIG. 4 .

[0058] As shown in FIG4 , the control method 300 begins at step 311 , where a cold start of the fuel cell system 200 is initiated. Specifically, at step 311 , a first gas and a second gas may be supplied to the fuel cell stack 210 , causing the first gas and the second gas to react within the fuel cell stack 210 and release heat and electrons. Because ice may be present within the fuel cell stack 210 at the beginning of the cold start, the reaction is initially weak.

[0059] Next, the control method 300 executes the cooling circuit control step 320, in which the coolant in the cooling circuit 260 stops flowing or flows at an initial flow rate u0 when the fuel cell system 200 starts a cold start. That is, in the cooling circuit control step 320, the control strategy of the coolant is determined. For example, at a lower temperature, the supply of coolant can be stopped during a cold start so that the internal temperature of the stack 210 rises as quickly as possible, while at a slightly higher temperature, the coolant can be supplied at a lower initial flow rate u0 during a cold start so that the temperature of the stack 210 is more uniform. The control strategy of the coolant can be stored in the storage device of the control device 100, and can be set, selected or modified according to the design and operating conditions of the fuel cell system.

[0060] Next, the control method 300 performs: a detection step 331, in which the initial temperature T0 of the stack 210 is detected; a calculation step 332, in which the internal temperature T of the stack 210 is calculated based on the initial temperature T0 of the stack 210 and the output current I and output voltage U output from the stack 210 to the load 240; a temperature judgment step 333, in which the calculated internal temperature T is compared with the threshold temperature T. th and the first flow adjustment step 334, in which the internal temperature T is greater than the threshold temperature T th In the case of increasing the flow rate Q of the coolant flowing through the fuel cell stack 210 in the cooling circuit 260 coolant .

[0061] Therefore, the present application provides a feasible method for estimating the internal temperature of the fuel cell stack 210. According to the above-described embodiment of the present application, through the various steps of the control method 300, the internal temperature of the fuel cell stack 210 can be effectively monitored. When the internal temperature is detected to be too high, the supply of coolant can be coordinated to fully utilize the heat generated inside the fuel cell stack 210 to achieve a fast and safe cold start.

[0062] Specifically, in the calculation step 332 , the internal temperature T is calculated based on the formula (1):

[0063] The internal temperature T of the stack 210 can be estimated using the above formula (1). For example, ignoring the heat dissipated from the stack 210, W = W1, where W is the internal heat of the stack 210 and W1 is the heat generated in the stack 210, as described above.

[0064] Furthermore, when it is necessary to monitor the internal temperature T of the stack 210 more accurately, the coolant inlet temperature T of the coolant entering the stack 210 is also detected in the detection step 331. coolantin and the coolant outlet temperature T of the coolant discharged from the stack 210coolantout , and in the calculation step 332 is also based on the coolant inlet temperature T coolantin and coolant outlet temperature T coolantout The heat W2 dissipated from the stack 210 by the coolant is calculated. Therefore, when the heat W2 dissipated from the stack 210 by the coolant is further considered, W=W1-W2. In this case, the internal temperature T is calculated based on the above formula (2) in the calculation step 332:

[0065] By using the above formula (2), the heat removed by the coolant can be taken into account, thereby estimating a more accurate internal temperature T of the fuel cell stack 210 .

[0066] Furthermore, in order to take into account the heat taken away from the fuel cell stack 210 by the first gas and the second gas, the first gas inlet temperature T of the first gas entering the fuel cell stack 210 is also detected in the detection step 331. 1in and the first gas outlet temperature T of the first gas discharged from the fuel cell stack 210 1out , and the second gas inlet temperature T of the second gas entering the fuel cell stack 210 2in and the second gas outlet temperature T of the second gas discharged from the fuel cell stack 210 2out , and in the calculation step 332, also based on the first gas inlet temperature T 1in , first gas outlet temperature T 1out , Second gas inlet temperature T 2in and the second gas outlet temperature T 2out The heat W3 dissipated from the stack 210 through the first gas and the heat W4 dissipated from the stack 210 through the second gas are calculated. Therefore, when further considering the heat W3 and W4 dissipated from the stack 210 through the first gas and the second gas, respectively, W = W1-W2-W3-W4. In this case, the internal temperature T is calculated based on the above formula (3) in the calculation step 332:

[0067] The above formula (3) can further take into account the heat dissipated from the fuel cell stack 210 through the coolant, the first gas, and the second gas, thereby estimating a more accurate internal temperature T of the fuel cell stack 210 .

[0068] According to an embodiment of the present application, after the flow adjustment step 334, a flow determination step 335 may be performed to determine the flow rate Q of the coolant. coolant Is it increased to be greater than the first predetermined flow rate u1, wherein the first predetermined flow rate u1 is associated with the target power of the pump 263 for pumping the coolant. As described above, when the adjustment module 40 attempts to increase the coolant flow rate Q coolantWhen the flow rate Q of the coolant increases to a value greater than the first predetermined flow rate u1, the pump 263 will be required to output a power greater than the target power, which is harmful to the safe operation of the pump 263. Therefore, the control method 300 further includes adjusting the coolant flow rate Q coolant If the coolant flow rate Q is greater than the first predetermined flow rate u1, the emergency shutdown step 312 is executed, in which the cold start of the fuel cell system 200 is stopped. coolant If the flow rate is less than or equal to the first predetermined flow rate u1 , the process returns to the detection step 331 to continue monitoring the change of the internal temperature T of the fuel cell stack 210 .

[0069] As previously analyzed, the degree of dehydration of the membrane electrode assembly is correlated with the high-frequency resistance (HFR) of the stack 210. Therefore, irreversible damage to the membrane electrode assembly can be avoided by monitoring the high-frequency resistance (HFR). Therefore, according to an embodiment of the present application, the control method 300 further includes a measurement step 340, in which the high-frequency resistance (HFR) of the stack 210 is measured. Since the measurement of the high-frequency resistance (HFR) is well known, the steps for measuring the high-frequency resistance (HFR) will not be described in further detail herein.

[0070] Next, the control method 300 may also include a first resistance judgment step 351, in which the high-frequency resistance HFR is compared with a first resistance threshold ε1 (which corresponds to the critical value of the high-frequency resistance HFR of the fuel cell stack 210), and when the high-frequency resistance HFR is greater than the first resistance threshold ε1, an emergency shutdown step 312 is executed to stop the cold start process of the fuel cell system 200 to avoid damaging the fuel cell stack 210.

[0071] Furthermore, the control method 300 may further include a second resistance determination step 352, in which the high frequency resistance HFR is compared with a second resistance threshold ε2, and when the high frequency resistance HFR is greater than the second resistance threshold ε2, a second flow adjustment step 354 is executed, in which the flow rate Q of the coolant is adjusted. coolant Increase to a value greater than the second predetermined flow rate u2, wherein the first resistance threshold ε1 is greater than the second resistance threshold ε2. In this way, when the membrane electrode assembly has experienced a certain degree of dehydration but has not yet reached a critical state, an alarm can be issued to the user, and the coolant flow rate Q can be increased. coolant to avoid further dehydration.

[0072] Furthermore, the control method 300 further includes a third resistance determination step 353, in which the high frequency resistance HFR is compared with a third resistance threshold ε3, and when the high frequency resistance HFR is greater than the third resistance threshold ε3, a third flow adjustment step 355 is executed, in which the flow rate Q of the coolant is adjusted. coolantIncrease to a value greater than the third predetermined flow rate u3, wherein the second resistance threshold ε2 is greater than the third resistance threshold ε3, and the second predetermined flow rate u2 is greater than the third predetermined flow rate u3. In this way, the user can be reminded to pay attention when the membrane electrode assembly just begins to dehydrate and increase the coolant flow rate Q coolant , slowing down the development of dehydration.

[0073] If the high-frequency resistance HFR is equal to or less than the third resistance threshold ε3, it can be considered that the membrane electrode assembly in the stack 210 is not dehydrated, so the control method 300 can return to the measurement step 340 to continue monitoring the change of the high-frequency resistance HFR.

[0074] All or part of the steps of the control method disclosed above can be implemented as a computer-readable storage medium. Therefore, according to an embodiment of the present application, a computer-readable storage medium is also provided, on which computer instructions are stored. When the computer instructions are executed by one or more processors, the one or more processors are caused to perform the steps of the control method described above.

[0075] From the above description, it can be seen that the fuel cell system and its cold start control method and control device of the present application can fully utilize the heat generated inside the fuel cell stack during the cold start process to heat up the fuel cell stack as quickly as possible, and can effectively monitor the internal temperature of the fuel cell stack and the degree of dehydration of the membrane electrode assembly, and cooperate with the flow adjustment of the coolant to achieve a fast and safe cold start.

[0076] The present application has been described in detail above with reference to specific embodiments. It is apparent that the above description and the embodiments shown in the accompanying drawings are to be understood as illustrative only and do not constitute limitations on the present application. Those skilled in the art may make various modifications or alterations to the present application without departing from the spirit of the present application, and such modifications or alterations do not depart from the scope of the present application.

Claims

1. A control device (100) for controlling the cold start of a fuel cell system (200), the fuel cell system (200) comprising a stack (210), a load (240) and a cooling circuit (260), the stack (210) comprising electrode plates and a membrane electrode assembly, the control device (100) comprising: A detection module (10) configured to detect an initial temperature T0 of the stack (210); A calculation module (20) configured to calculate an internal temperature T of the stack (210) based on the initial temperature T0, an output current I and an output voltage U output from the stack (210) to the load (240); A determination module (30) configured to compare the calculated internal temperature T with a threshold temperature T th for comparison; Adjustment module (40), which is configured to increase the flow rate Q of the coolant flowing through the stack (210) in the cooling circuit (260) when the internal temperature T is greater than the threshold temperature T th . coolant .

2. The control device (100) according to claim 1, wherein, The calculation module (20) is configured to calculate the internal temperature T based on the following formula: Wherein, W is the internal heat of the stack (210), and the internal heat is calculated by subtracting the heat dissipated from the stack (210) from the heat generated in the stack (210); Among them, the heat generated in the stack (210) is W1, and W1 = I*(E0 - U), where E0 is the reversible voltage in the stack (210), C BPP , C MEA and C coolant are the specific heat capacities of the plate, the membrane electrode assembly, and the coolant respectively, m BPP and m MEA are the masses of the plate and the membrane electrode assembly respectively, ρ coolant is the density of the coolant, and V coolant-chamber is the volume of the coolant present in the cooling cavity of the stack (210); Wherein, when the heat dissipated from the stack (210) is ignored, W = W1.

3. The control device (100) according to claim 2, wherein, The detection module (10) is further configured to detect the coolant inlet temperature T of the coolant entering the stack (210). coolantin and the coolant outlet temperature T of the coolant discharged from the stack (210). coolantout And the calculation module (20) is configured to further calculate the heat W2 dissipated from the stack (210) through the coolant based on the coolant inlet temperature T coolantin and the coolant outlet temperature T coolantout where W2 = C coolant *ρ coolant *Q coolant *(T coolantout - T coolantin ); Wherein, when further considering the heat W2 dissipated from the stack (210) through the coolant, W = W1 - W2.

4. The control device (100) according to claim 3, wherein, The detection module (10) is further configured to detect a first gas inlet temperature T of a first gas entering the fuel cell stack (210). 1in and a first gas outlet temperature T of the first gas discharged from the fuel cell stack (210), 1out and a second gas inlet temperature T of a second gas entering the fuel cell stack (210), 2in and a second gas outlet temperature T of the second gas discharged from the fuel cell stack (210), 2out and The calculation module (20) is configured to further calculate based on the first gas inlet temperature T 1in , the first gas outlet temperature T 1out , the second gas inlet temperature T 2in and the second gas outlet temperature T 2out as follows: The heat W3 dissipated from the fuel cell stack (210) by the first gas, W3 = C1 * ρ1 * Q1 * (T 1out - T 1in ), where C1 is the specific heat capacity of the first gas, and ρ1 and Q1 are the density and flow rate of the first gas respectively; and The heat W4 dissipated from the stack (210) by the second gas, W4 = C2 * ρ2 * Q2 * (T 2out - T 2in ), where C2 is the specific heat capacity of the second gas, and ρ2 and Q2 are the density and flow rate of the second gas respectively; Wherein, when further considering the heat W3 and W4 dissipated from the stack (210) through the first gas and the second gas respectively, W = W1 - W2 - W3 - W4.

5. The control device (100) according to claim 1, wherein, The determination module (30) is further configured to determine whether the flow rate Q of the coolant coolant is increased to be greater than the first predetermined flow rate u1, where the first predetermined flow rate u1 is associated with the target power of the pump (263) for pumping the coolant, and The control device (100) further comprises an output module (60) configured to, during the cold... The flow rate Q of the quenching agent coolant Output an emergency shutdown message when it is greater than the first predetermined flow rate u1.

6. The control device (100) according to any one of claims 1 to 5, wherein, The control device (100) further comprises a measurement module (50) configured to measure a high-frequency resistance (HFR) of the stack (210).

7. The control device (100) according to claim 6, wherein, The determination module (30) is further configured to compare the high-frequency resistance (HFR) with a first resistance threshold ε1, and an output module (60) of the control device (100) is configured to output an emergency shutdown message when the high-frequency resistance (HFR) is greater than the first resistance threshold ε1.

8. The control device (100) according to claim 7, wherein, The determination module (30) is further configured to compare the high-frequency resistor (HFR) with a second resistance threshold ε2, and the output module (60) is further configured to issue an alarm message when the high-frequency resistor (HFR) is greater than the second resistance threshold ε2, and the adjustment module (40) is configured to increase the flow rate Q of the coolant coolant to be greater than a second predetermined flow rate u2, where the first resistance threshold ε1 is greater than the second resistance threshold ε2.

9. The control device (100) according to claim 8, wherein, The determination module (30) is further configured to compare the high-frequency resistor (HFR) with a third resistance threshold ε3, and the output module (60) is further configured to output a reminder message when the high-frequency resistor (HFR) is greater than the third resistance threshold ε3, and the adjustment module (40) is configured to increase the flow rate Q of the coolant coolant to be greater than a third predetermined flow rate u3, where the second resistance threshold ε2 is greater than the third resistance threshold ε3, and the second predetermined flow rate u2 is greater than the third predetermined flow rate u3.

10. The control device (100) according to claim 1, wherein, The adjustment module (40) is further configured to stop the coolant in the cooling circuit (260) from flowing or flow at an initial flow rate u0 when the fuel cell system (200) starts a cold start.

11. A control method (300) for controlling the cold start of a fuel cell system (200), the fuel cell system (200) comprising a stack (210), a load (240) and a cooling circuit (260), the stack (210) comprising electrode plates and a membrane electrode assembly, the control method (300) comprising: A detection step (331) in which an initial temperature T0 of the stack (210) is detected; A calculation step (332) in which an internal temperature T of the stack (210) is calculated based on the initial temperature T0, an output current I and an output voltage U output from the stack (210) to the load (240); Temperature determination step (333), in which the calculated internal temperature T is compared with a threshold temperature T th in the temperature determination step (333). The first flow rate adjustment step (334), in which, when the internal temperature T is greater than the threshold temperature T th the flow rate Q of the coolant flowing through the fuel cell stack (210) in the cooling circuit (260) is increased coolant .

12. The control method (300) according to claim 11, wherein, In the calculation step (332), the internal temperature T is calculated based on the following formula: Wherein, W is the internal heat of the stack (210), and the internal heat is calculated by subtracting the heat dissipated from the stack (210) from the heat generated in the stack (210); Among them, the heat generated in the stack (210) is W1, and W1 = I * (E0 - U), where E0 is the reversible voltage in the stack (210), C BPP , C MEA and C coolant are the specific heat capacities of the plate, the membrane electrode assembly, and the coolant respectively, m BPP and m MEA are the masses of the plate and the membrane electrode assembly respectively, ρ coolant is the density of the coolant, and V coolant-chamber is the volume of the coolant present in the cooling cavity of the stack (210); Wherein, when the heat dissipated from the stack (210) is ignored, W = W1.

13. The control method (300) according to claim 12, wherein, In the detection step (331), the coolant inlet temperature T of the coolant entering the stack (210) is also detected coolantin and the coolant outlet temperature T of the coolant discharged from the stack (210), coolantout and in the calculation step (332), based on the coolant inlet temperature T coolantin and the coolant outlet temperature T coolantout the heat quantity W2 dissipated from the stack (210) through the coolant is calculated, W2 = C coolant *ρ coolant *Q coolant *(T coolantout - T coolantin ); Wherein, when further considering the heat W2 dissipated from the stack (210) through the coolant, W = W1 - W2.

14. The control method (300) according to claim 13, wherein, In the detection step (331), the first gas inlet temperature T of the first gas entering the fuel cell stack (210) is also detected 1in and the first gas outlet temperature T of the first gas discharged from the fuel cell stack (210), 1out and the second gas inlet temperature T of the second gas entering the fuel cell stack (210), 2in and the second gas outlet temperature T of the second gas discharged from the fuel cell stack (210), 2out and In the calculation step (332), it is also calculated based on the first gas inlet temperature T 1in , the first gas outlet temperature T 1out , the second gas inlet temperature T 2in and the second gas outlet temperature T 2out as follows: The heat W3 dissipated from the fuel cell stack (210) by the first gas, W3 = C1 * ρ1 * Q1 * (T 1out - T 1in ), where C1 is the specific heat capacity of the first gas, and ρ1 and Q1 are the density and flow rate of the first gas respectively; and The heat W4 dissipated from the fuel cell stack (210) by the second gas, W4 = C2 * ρ2 * Q2 * (T 2out - T 2in ), where C2 is the specific heat capacity of the second gas, and ρ2 and Q2 are the density and flow rate of the second gas respectively; Wherein, when further considering the heat W3 and W4 dissipated from the stack (210) through the first gas and the second gas respectively, W = W1 - W2 - W3 - W4.

15. The control method (300) according to claim 11, wherein, The control method (300) further includes a flow rate determination step (335), in which it is determined whether the flow rate Q of the coolant coolant is increased to be greater than the first predetermined flow rate u1, where the first predetermined flow rate u1 is associated with the target power of a pump (263) for pumping the coolant, and The control method (300) further includes an emergency shutdown step (312) performed when the flow rate Q of the coolant coolant is greater than the first predetermined flow rate u1, and in the emergency shutdown step (312), the cold start of the fuel cell system (200) is stopped.

16. The control method (300) according to any one of claims 11 to 15, wherein, The control method (300) further includes a measurement step (340), in which the high-frequency resistance (HFR) of the stack (210) is measured.

17. The control method (300) according to claim 16, wherein, The control method (300) further includes: A first resistance determination step (351), in which the high-frequency resistance (HFR) is compared with a first resistance threshold ε1, and when the high-frequency resistance (HFR) is greater than the first resistance threshold ε1, an emergency shutdown step (312) is executed, in which the cold start of the fuel cell system is stopped.

18. The control method (300) according to claim 17, wherein, The control method (300) further includes: Second resistor determination step (352), in the second resistor determination step (352), the high-frequency resistor (HFR) is compared with a second resistor threshold ε2, and when the high-frequency resistor (HFR) is greater than the second resistor threshold ε2, a second flow rate adjustment step (354) is executed, and in the second flow rate adjustment step (354), the flow rate Q of the coolant coolant is increased to be greater than a second predetermined flow rate u2, where the first resistor threshold ε1 is greater than the second resistor threshold ε2.

19. The control method (300) according to claim 18, wherein, The control method (300) further includes: Third resistor determination step (353), in the third resistor determination step (353), the high-frequency resistor (HFR) is compared with a third resistor threshold value ε3, and when the high-frequency resistor (HFR) is greater than the third resistor threshold value ε3, a third flow rate adjustment step (355) is executed, and in the third flow rate adjustment step (355), the flow rate Q of the coolant is coolant increased to At a third predetermined flow rate u3, wherein the second resistance threshold ε2 is greater than the third resistance threshold ε3, and the second predetermined flow rate u2 is greater than the third predetermined flow rate u3.

20. The control method (300) according to claim 11, wherein, The control method (300) further includes a cooling circuit control step (320), in which the coolant in the cooling circuit (260) is stopped from flowing or flows at an initial flow rate u0 when the fuel cell system (200) starts a cold start.

21. A fuel cell system (200), comprising: A stack (210); A first gas supply device (220) configured to supply a first gas to the stack (210); A second gas supply device (230) configured to supply a second gas to the stack (210); A cooling circuit (260) configured to allow a coolant to flow through the stack (210); and A control device (100) according to any one of claims 1 to 10, wherein the control device (100) is configured to control the cold start of the fuel cell system (200).

22. A computer-readable storage medium having computer instructions stored thereon, which when executed by one or more processors cause the one or more processors to perform the steps of the control method according to any one of claims 11 to 20.

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