Method of starting a fuel cell
By detecting the stack temperature and high-frequency impedance under low-temperature conditions, and utilizing the coordinated control of the stack self-heating and thermal management system, the problem of proton exchange membrane water content fluctuation was solved, enabling rapid cold start and efficient operation of the fuel cell, and improving electrochemical reaction efficiency and reliability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ROBERT BOSCH GMBH
- Filing Date
- 2024-11-06
- Publication Date
- 2026-05-08
AI Technical Summary
Existing technologies neglect the water content of the proton exchange membrane when starting up fuel cells in low-temperature environments, which affects the electrochemical reaction efficiency and fuel cell performance. Furthermore, existing methods may cause fluctuations in the water content of the proton exchange membrane, affecting the rapid start-up and reliability of the fuel cell stack.
By detecting the temperature and high-frequency impedance of the fuel cell stack, the stack can be rapidly heated in a low-temperature environment using its self-heating mechanism. When the high-frequency impedance reaches an inflection point, the thermal management system is activated to control the water content of the proton exchange membrane, ensuring it remains at an appropriate level and preventing overheating.
It enables rapid cold start of fuel cells in low-temperature environments, maintains the health of proton exchange membranes, improves electrochemical reaction efficiency, ensures the safety and reliability of fuel cells, and enhances user experience.
Smart Images
Figure CN122000382A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of fuel cell technology, and more specifically, to a method for starting a fuel cell. Background Technology
[0002] Fuel cells have become one of the main power generation technologies due to their high power generation efficiency, low environmental pollution, and high specific energy. As a typical fuel cell, the proton exchange membrane fuel cell (PEMFC) is a popular type of fuel cell used in vehicles. A PEMFC generally consists of a solid polymer electrolyte proton-conducting membrane, such as a perfluorosulfonic acid membrane. The anode and cathode typically comprise finely divided catalyst particles, usually platinum (Pt), supported on carbon particles and mixed with ionomers. The catalyst mixture is deposited on opposite sides of the membrane. The combination of the anode catalyst mixture, the cathode catalyst mixture, and the membrane defines the membrane electrode assembly (MEA).
[0003] A fuel cell stack includes a series of bipolar plates positioned between several membrane electrode assemblies (MEAs) within the stack, with the bipolar plates and MEAs positioned between two spacers. Each bipolar plate includes an anode side and a cathode side for adjacent individual cells within the stack. An anode gas flow channel is provided on the anode side of the bipolar plate, allowing anode gas to flow to the corresponding MEA assembly. A cathode gas flow channel is provided on the cathode side of the bipolar plate, allowing cathode gas to flow to the corresponding MEA assembly.
[0004] For hydrogen-oxygen fuel cells, the stack needs to operate at a suitable temperature to carry out electrochemical reactions and generate electricity, with water and heat being produced as byproducts. Some existing technologies for starting fuel cells in low-temperature environments aim to utilize the heat generated by the stack itself to raise its temperature to a suitable level. Therefore, the thermal management system is activated to help cool the stack only after the temperature has reached the optimal level. However, this ignores the water content of the proton exchange membrane, which may result in the membrane's water content dropping to a low level by the time the thermal management system is activated. This negatively impacts the efficiency of the electrochemical reaction and the overall performance of the fuel cell.
[0005] Therefore, there is an urgent need in this field for a technical solution that can balance the cold start speed of fuel cells and the water content of proton exchange membranes. Summary of the Invention
[0006] To address the problems in the prior art, this disclosure proposes an improved method for starting a fuel cell, the fuel cell including a stack and a coolant circulation line connecting the coolant inlet and coolant outlet of the stack, the method comprising the following steps:
[0007] S100: Supply cathode gas and anode gas to the fuel cell stack, and detect the stack temperature T. stk ;
[0008] S200: Set the stack temperature T stk With the first predetermined temperature T prd1 Compare, if T stk ≥T prd1 If T stk <T prd1 If so, then execute S400;
[0009] S300: Drives the coolant to flow in the coolant circulation line;
[0010] S400: According to the predetermined time sequence t0, t1, ..., t n The high-frequency impedance (HFR) of the fuel cell stack was detected.
[0011] S500: Will be at time t i+1 Detected high-frequency impedance HFR i+1 With at time t i Detected high-frequency impedance HFR i Compare, if HFR i+1 <HFR i If so, return S400; if HFR i+1 ≥HFR i Then execute S600, where i = 0, 1, 2, ..., n; and
[0012] S600: Drives the coolant to flow in the coolant circulation line.
[0013] Similarly, in order to address the problems in the prior art described above, this disclosure proposes another improved method for starting a fuel cell, the method comprising the following steps:
[0014] S100: Supply cathode gas and anode gas to the fuel cell stack, and detect the stack temperature T. stk ;
[0015] S200: Set the stack temperature T stk With the first predetermined temperature T prd1 Compare, if T stk ≥T prd1 If T stk <T prd1 If so, then execute S400;
[0016] S300: Drives the coolant to flow in the coolant circulation line;
[0017] S400: According to the predetermined time sequence t0, t1, ..., t n The high-frequency impedance (HFR) of the fuel cell stack was detected.
[0018] S500: Set the stack temperature T stk With the second predetermined temperature T prd2 Compare, and at time t i+1 Detected high-frequency impedance HFR i+1 With at time t i Detected high-frequency impedance HFR i Compare, if T stk <T prd2 And HFR i+1 <HFR i If T stk ≥T prd2 Or HFR i+1 ≥HFR i Then execute S600, where i = 0, 1, 2, ..., n; and
[0019] S600: Drives the coolant to flow in the coolant circulation line.
[0020] To further address the problems in the prior art described above, this disclosure proposes an improved method for starting a fuel cell, the method comprising the following steps:
[0021] S100: Supply cathode gas and anode gas to the fuel cell stack, and detect the stack temperature T. stk ;
[0022] S200: Set the stack temperature T stk With the first predetermined temperature T prd1 Compare, if T stk ≥T prd1 If T stk <T prd1 If so, then execute S400;
[0023] S300: Drives the coolant to flow in the coolant circulation line;
[0024] S400: According to the predetermined time sequence t0, t1, ..., t n The high-frequency impedance (HFR) of the fuel cell stack was detected.
[0025] S500: Will be at time t i+1 Detected high-frequency impedance HFR i+1 With at time t i Detected high-frequency impedance HFR i Compare, and at time ti+2 Detected high-frequency impedance HFR i+2 With at time t i+1 Detected high-frequency impedance HFR i+1 Compare, if HFR i+1 <HFR i Or HFR i+2 <HFR i+1 If so, return S400; if HFR i+1 ≥HFR i And HFR i+2 ≥HFR i+1 Then execute S600, where i = 0, 1, 2, ..., n; and
[0026] S600: Drives the coolant to flow in the coolant circulation line.
[0027] This disclosure may be embodied in the illustrative embodiments shown in the accompanying drawings. However, it should be noted that the drawings are merely illustrative, and any variations contemplated under the teachings of this disclosure should be considered to be included within the scope of this disclosure. Attached Figure Description
[0028] The accompanying drawings illustrate exemplary embodiments of this disclosure. These drawings should not be construed as necessarily limiting the scope of this disclosure, wherein:
[0029] Figure 1 This is a schematic block diagram of a fuel cell to which the method for starting a fuel cell according to this disclosure applies, and the direction of fluid flow is indicated by arrows;
[0030] Figure 2 This is a schematic flowchart of a method for starting a fuel cell according to one embodiment of the present disclosure; and
[0031] Figure 3 This is a schematic flowchart of a method for starting a fuel cell according to another embodiment of the present disclosure. Detailed Implementation
[0032] Further features and advantages of this disclosure will become more apparent from the following description with reference to the accompanying drawings. Exemplary embodiments of this disclosure are shown in the drawings, and the drawings are not necessarily drawn to scale. However, this disclosure can be implemented in many different forms and should not be construed as necessarily limited to the exemplary embodiments shown herein. Rather, these exemplary embodiments are provided merely to illustrate this disclosure and to convey the spirit and essence of this disclosure to those skilled in the art.
[0033] This disclosure aims to provide a method for starting a proton exchange membrane (PEM) fuel cell. This method disables and then enables the thermal management system during low-temperature startup (i.e., cold start), thereby utilizing the heat generated within the fuel cell stack to raise the stack temperature to a suitable operating range and preventing overheating. This not only achieves rapid cold start but also ensures the safety and reliability of the fuel cell. Specifically, the method according to this disclosure ensures that the water content of the PEM is not too low during cold start, thus preventing membrane dryness (i.e., excessive dryness of the PEM) that could affect its health and lifespan. This maintains the health and lifespan of the PEM, contributing to extended fuel cell lifespan and improved reliability. More specifically, the method according to this disclosure can also maintain the water content of the proton exchange membrane at a high level during cold start, thereby ensuring that the fuel cell has high operating performance even during cold start. This enables fuel cell-powered vehicles (e.g., electric vehicles, hybrid vehicles, etc.) to obtain sufficient power from the fuel cell more quickly even in low-temperature environments, thus achieving rapid cold start of the vehicle. Compared with existing vehicles that require a longer cold start time or even preheating before cold start, this will undoubtedly significantly improve the user experience.
[0034] The following describes in detail, with reference to the accompanying drawings, alternative but non-limiting embodiments of the method for starting a fuel cell according to this disclosure.
[0035] refer to Figure 1 The diagram illustrates a schematic block diagram of a fuel cell to which the method for starting a fuel cell according to this disclosure is applicable, with arrows indicating the direction of fluid flow. Figure 1 As shown, the fuel cell 100, serving as a power source for vehicle 10, includes a stack 110 and an auxiliary system (i.e., a BOP) for supplying anode gas, cathode gas, coolant, etc., to the stack 110. The fuel cell 100 is suitable for use as a DC power source in vehicle 10 to drive a traction motor (not shown), thereby providing power to vehicle 10. Of course, the above applications are merely exemplary; fuel cell 100 can also be used as a power source for other vehicles (e.g., marine vehicles, aerospace vehicles, etc.) and can also be used in power plants or other facilities requiring onboard DC power generation. In this document, fuel cell 100 will be described in the context of its use as a power source for vehicle 10, but this is not intended to limit fuel cell 100 to such applications.
[0036] like Figure 1As shown, the fuel cell 100 includes a stack 110 comprising a plurality of individual cells 111 stacked together. Each individual cell 111 includes a proton exchange membrane, an anode-side catalyst layer, an anode-side gas diffusion layer, and a bipolar plate located on one side of the proton exchange membrane, and a cathode-side catalyst layer, a cathode-side gas diffusion layer, and a bipolar plate located on the other side of the proton exchange membrane. As a supply system for the fuel cell 100, the fuel cell 100 also includes a compressor 120 that supplies oxygen-containing gas (e.g., compressed air) from a cathode gas source such as the atmosphere or an oxygen storage tank to the stack 110 via a cathode gas delivery line P1, and an injector 140 that supplies hydrogen-containing gas (e.g., hydrogen or other hydrogen-containing gases such as methane or natural gas) from an anode gas source 130 such as a hydrogen storage tank to the stack 110 via an anode gas delivery line P2. As a thermal management system for the fuel cell 100, the fuel cell 100 also includes a coolant pump 150 that drives the coolant to circulate between the inside and outside of the stack 110 via a coolant circulation line L1, a radiator 161 disposed on the coolant circulation line L1, and a fan 162 for cooling the radiator 161.
[0037] During operation of the fuel cell 100, the anode gas supplied to the stack 110 by the injector 140 flows through the anode gas flow field of each bipolar plate and is diffused to the anode-side catalyst layer by the anode-side gas diffusion layer. Similarly, the cathode gas supplied to the stack 110 flows through the cathode gas flow field of each bipolar plate and is diffused to the cathode-side catalyst layer by the cathode-side gas diffusion layer. At the anode-side catalyst layer, the anode gas decomposes into protons (i.e., hydrogen protons) and electrons. Protons can be transported to the cathode-side catalyst layer by water molecules in the proton exchange membrane, while electrons, unable to pass through the proton exchange membrane, can only reach the cathode-side catalyst layer through an external circuit. This enables power supply to loads on external circuits (e.g., the traction motor of vehicle 10), while protons and electrons reaching the cathode-side catalyst layer combine with the cathode gas to generate water and heat. The water, along with the cathode gas, can be discharged from the fuel cell stack 110 via the cathode gas exhaust line P3 and then released into the atmosphere. The heat can be absorbed by the coolant inside the fuel cell stack 110. The coolant, having absorbed heat, can be discharged from the fuel cell stack 110 via the coolant circulation line L1 and cooled by the fan 162 at the radiator 161 before flowing back into the fuel cell stack 110 to continue absorbing heat and ensuring a uniform temperature distribution within the stack. Additionally, unconsumed anode gas can be discharged from the fuel cell stack 110 via the anode gas exhaust line P4 and, after dilution with air, discharged into the atmosphere or returned to the fuel cell stack 110 via the anode gas circulation line (not shown).
[0038] As mentioned earlier, the catalyst layer and proton exchange membrane (PEM) are the core components that allow the anolyte and cathode gases to undergo electrochemical reactions. The catalyst layer lowers the activation energy of both gases, thus promoting their electrochemical reaction. The PEM allows water molecules to transport protons while blocking electrons, enabling protons and electrons from the decomposition of the anolyte gas to combine with the cathode gas at the catalyst layer on the cathode side, thereby completing the electrochemical reaction. Therefore, the activity of the catalyst layer and the water content of the PEM are two major factors affecting the efficiency of the electrochemical reaction. The activity of the catalyst layer is mainly affected by temperature, while the water content of the PEM is influenced by various factors. For example, water produced by the electrochemical reaction can replenish the water in the PEM, thus helping to increase its water content. However, the heat generated by the fuel cell stack 110 can cause water evaporation from the PEM, potentially reducing its water content. In addition, the water content of the proton exchange membrane can be reflected by the high-frequency impedance of the fuel cell stack 110. Generally, the higher the water content of the proton exchange membrane, the higher its conductivity, and the lower the high-frequency impedance of the fuel cell stack 110; conversely, the lower the water content of the proton exchange membrane, the lower its conductivity, and the higher the high-frequency impedance of the fuel cell stack 110.
[0039] To ensure the electrochemical reaction efficiency of the fuel cell stack 110 and maintain the operating performance of the fuel cell 100, the stack 110 needs to operate at a suitable operating temperature (e.g., 60°C-80°C) and maintain a high level of water content in the proton exchange membrane, i.e., a low level of high-frequency impedance. However, in existing fuel cell startup methods, especially those utilizing stack self-heating for cold starts in low-temperature environments, only the stack temperature is considered, and the thermal management system is activated when the stack temperature rises to a suitable operating temperature. This neglects the stack's high-frequency impedance, i.e., the water content of the proton exchange membrane. The inventors of this application have discovered that, for fuel cell startup in low-temperature environments, existing startup methods may result in the stack's high-frequency impedance already being at a high level when the stack temperature rises to a certain point, i.e., the proton exchange membrane's water content already being at a low level. This adversely affects the stack's electrochemical reaction efficiency and the fuel cell's operating performance. Furthermore, the inventors of this application have discovered that during the cold start process achieved by self-heating of the fuel cell without activating the thermal management system, in the initial stage, due to the low temperature of the fuel cell, the rate at which the water content of the proton exchange membrane is replenished by water produced by the electrochemical reaction is faster than the rate at which it evaporates due to the heating of the fuel cell, resulting in an increase in the water content of the proton exchange membrane. However, in the subsequent stage, as the temperature of the fuel cell increases, the rate at which the water content of the proton exchange membrane evaporates due to the heating of the fuel cell is faster than the rate at which it is replenished by water produced by the electrochemical reaction, resulting in a decrease in the water content of the proton exchange membrane. In short, during the cold start process of the fuel cell, the water content of the proton exchange membrane exhibits a change that first increases and then decreases over time. Correspondingly, the high-frequency impedance of the fuel cell exhibits a change that first decreases and then increases over time.
[0040] Based on the above findings, the inventors of this application propose an improved cold-start strategy, which is implemented through the following method for starting a fuel cell. (Reference) Figure 2 The diagram illustrates a schematic flowchart of a method for starting a fuel cell according to one embodiment of the present disclosure. Figure 2 As shown, the method includes the following steps:
[0041] S100: Start compressor 120 to supply cathode gas to fuel cell stack 110, start injector 140 to supply anode gas to fuel cell stack 110, and detect the fuel cell stack temperature T of fuel cell stack 110. stkIn this step, the fuel cell stack 110 can be started by supplying cathode gas and anode gas to it, so that electrical energy can be generated through the electrochemical reaction of the cathode gas and anode gas within the fuel cell stack 110. Of course, as mentioned above, heat and water will be generated as byproducts of the electrical energy generation. Additionally, the energy can be generated through the coolant inlet 110 of the fuel cell stack 110. i A temperature sensor is installed at the location to detect the coolant inlet temperature T. cti And take it as the stack temperature T stk Alternatively, it can be done through the coolant outlet 110 of the fuel cell stack 110. o A temperature sensor is installed at the outlet to detect the coolant outlet temperature T. cto And take it as the stack temperature T stk Alternatively, the coolant inlet temperature T can be... cti With coolant outlet temperature T cto The average value is used as the stack temperature T. stk ;
[0042] S200: The detected stack temperature T stk With the first predetermined temperature T prd1 For comparison, if the stack temperature T stk Higher than or equal to the first predetermined temperature T prd1 If the stack temperature T is..., then proceed to step S300; stk Below the first predetermined temperature T prd1 Then, step S400 is executed. In this step, the stack temperature T is controlled. stk With the first predetermined temperature T prd1 A comparison is made to determine whether the cold start strategy according to this disclosure needs to be implemented. Specifically, if the stack temperature T stk Higher than or equal to the first predetermined temperature T prd1 If the temperature T is normal, then the fuel cell stack 110 is considered to be in a normal temperature environment, and therefore the fuel cell stack 110 can start normally, thus eliminating the need to execute the cold start strategy according to this disclosure; conversely, if the fuel cell stack temperature T is normal, then the fuel cell stack 110 is considered to be in a normal temperature environment, and therefore the fuel cell stack 110 can start normally, thus eliminating the need to execute the cold start strategy according to this disclosure; stk Below the first predetermined temperature T prd1 If the temperature is low, the fuel cell stack 110 is considered to be in a low-temperature environment and the cold start strategy according to this disclosure needs to be executed. Specifically, the first predetermined temperature T... prd1The temperature can be set to 0℃, -10℃, -20℃, -30℃, etc., or it can be calibrated in multiple experiments conducted on the fuel cell 100 beforehand. For example, multiple temperatures can be selected in advance, and the fuel cell 100 can be started multiple times at each temperature. The start-up time of the fuel cell 100 at each temperature (i.e., the time required for the fuel cell 100 to output rated power from start-up) can be recorded. If the probability that the start-up time of the fuel cell 100 is longer than 1 minute (or other durations) at a certain temperature exceeds 50% (or other probabilities), then that temperature can be used as the first predetermined temperature T. prd1 ;
[0043] S300: The coolant pump 150 and fan 162 are started to drive the coolant to flow in the coolant circulation line L1, that is, to circulate the coolant through the fuel cell stack 110 and the radiator 161, so that the coolant absorbs heat within the fuel cell stack 110 and dissipates heat at the radiator 161. Therefore, if it is determined in step S200 that the cold start strategy according to this disclosure is not required, step S300 is performed to start the coolant pump 150 and fan 162 to dissipate the heat generated within the fuel cell stack 110 due to the electrochemical reaction using the coolant, thereby helping to cool the fuel cell stack 110 and prevent overheating.
[0044] S400: According to the predetermined time sequence t0, t1, ..., t n The high-frequency impedance (HFR) of fuel cell 110 is detected. For example, over a predetermined time series t0, t1, ..., t n Each time t in i Electrochemical impedance spectroscopy (EIS) can be used to detect the high-frequency impedance (HFR) of fuel cell stack 110.
[0045] S500: Will be at time t i+1 Detected high-frequency impedance HFR i+1 With at time t i Detected high-frequency impedance HFR i Comparison, if the high-frequency impedance HFR i+1 Less than the high-frequency impedance HFR i Then return to step S400, if the high-frequency impedance HFR i+1 Greater than or equal to the high-frequency impedance HFR i Then execute step S600, where i = 0, 1, 2, ..., n; and
[0046] S600: Start the coolant pump 150 and fan 162 to drive the coolant to flow in the coolant circulation line L1, that is, to circulate the coolant through the fuel cell stack 110 and the radiator 161, so that the coolant absorbs heat in the fuel cell stack 110 and dissipates heat at the radiator 161.
[0047] Specifically, the predetermined time series t0, t1, ..., t n It can be in the form of an arithmetic sequence, that is, a predetermined time series t0, t1, ..., t n The time interval Δt between adjacent times in the time interval is fixed, so that t i+1 =t i +Δt.
[0048] As can be seen from steps S400-S600, if it is determined in step S200 that the cold start strategy according to this disclosure needs to be implemented, then step S400 is first executed to detect the high-frequency impedance HFR of the fuel cell stack 110; then, step S500 is executed to monitor the inflection point of the high-frequency impedance HFR from decreasing to increasing, which roughly corresponds to the minimum value of the high-frequency impedance HFR. Specifically, if the high-frequency impedance HFR at the next moment is less than the high-frequency impedance HFR at the previous moment, it is considered that the high-frequency impedance HFR is still decreasing, and the process returns to step S400 to continue detecting the high-frequency impedance HFR; if the high-frequency impedance HFR at the next moment is greater than or equal to the high-frequency impedance HFR at the previous moment, it is considered that the inflection point of the high-frequency impedance HFR from decreasing to increasing has been detected, and step S600 is executed to start the coolant pump 150 and the fan 162.
[0049] Under the above configuration, the coolant pump 150 and fan 162 can be disabled during the high-frequency impedance (HFR) decrease process to retain the heat generated within the fuel cell stack 110. This heat can then be used to heat the fuel cell stack 110, thereby increasing the stack temperature T. stkThe fuel cell stack 110 can rapidly rise towards a suitable operating temperature in a low-temperature environment through self-heating. Furthermore, if the inflection point of the high-frequency impedance HFR from decreasing to increasing is detected, the coolant pump 150 and fan 162 are activated to help cool the fuel cell stack 110 using coolant. This helps to suppress the rate at which the water content of the proton exchange membrane evaporates due to the heating of the fuel cell stack, thereby maintaining the water content of the proton exchange membrane at a high level. In other words, by activating the coolant pump 150 and fan 162 based on the inflection point of the high-frequency impedance HFR from decreasing to increasing (i.e., its minimum value), the high-frequency impedance HFR can be maintained at a low level, or even maintained near its minimum value. As mentioned above, this helps to improve the efficiency of the electrochemical reaction and thus improve the operating performance of the fuel cell 100. Therefore, the cold-start strategy of this disclosure enables the stack to heat up rapidly during fuel cell startup in low-temperature environments by utilizing the stack's self-heating. Furthermore, the thermal management system is activated after detecting the inflection point where the stack's high-frequency impedance changes from decreasing to increasing. This allows for rapid stack heating through self-heating, facilitating quick startup, while simultaneously maintaining the stack's high-frequency impedance at a low level, effectively keeping the proton exchange membrane's water content at a high level. This improves the efficiency of the electrochemical reaction and enhances the fuel cell's performance. Therefore, compared to existing technologies that focus solely on stack temperature while neglecting proton exchange membrane water content, the cold-start strategy of this disclosure significantly improves the user experience of using fuel cells in low-temperature environments.
[0050] According to an optional implementation, step S500 involves: at time t i+1 Detected high-frequency impedance HFR i+1 With at time t i Detected high-frequency impedance HFR i Compare, and at time t i+2 Detected high-frequency impedance HFR i+2 With at time t i+1 Detected high-frequency impedance HFR i+1 Comparison, if the high-frequency impedance HFR i+1 Less than the high-frequency impedance HFR i Or high-frequency impedance HFR i+2 Less than the high-frequency impedance HFR i+1 Then return to step S400, if the high-frequency impedance HFR i+1 Greater than or equal to the high-frequency impedance HFR i And high frequency impedance HFR i+2 Greater than or equal to the high-frequency impedance HFR i+1If the high-frequency impedance HFR is greater than or equal to the high-frequency impedance HFR of the previous moment twice consecutively, then step S600 is executed. Under the above configuration, in step S500, only if the high-frequency impedance HFR of the next moment is twice greater than or equal to the high-frequency impedance HFR of the previous moment is it considered that an inflection point from decreasing to increasing high-frequency impedance HFR has been detected, and step S600 is executed to start the coolant pump 150 and fan 162; otherwise, it is considered that the high-frequency impedance HFR is still decreasing, and the process returns to step S400 to continue detecting the high-frequency impedance HFR. This avoids mistaking the numerical oscillation of the high-frequency impedance HFR during its decrease as an inflection point from decreasing to increasing high-frequency impedance HFR. Therefore, it avoids starting the coolant pump 150 and fan 162 before the true inflection point of the high-frequency impedance HFR appears. This allows the fuel cell stack 110 sufficient time to self-heat for rapid startup and ensures that the high-frequency impedance HFR can decrease to the inflection point, thereby more reliably improving the efficiency of the electrochemical reaction and enhancing the working performance of the fuel cell.
[0051] According to an optional implementation, step S500 involves: setting the stack temperature T of the fuel cell stack 110... stk With the second predetermined temperature T prd2 Compare, and at time t i+1 Detected high-frequency impedance HFR i+1 With at time t i Detected high-frequency impedance HFR i For comparison, if the stack temperature T stk Below the second predetermined temperature T prd2 And high frequency impedance HFR i+1 Less than the high-frequency impedance HFR i Then return to step S400; if the stack temperature T stk Higher than or equal to the second predetermined temperature T prd2 Or high-frequency impedance HFR i+1 Greater than or equal to the high-frequency impedance HFR i Then proceed to step S600. Specifically, the second predetermined temperature T... prd2 It can be set to determine whether fuel cell stack 110 has an overheating risk; that is, if the fuel cell stack temperature T of fuel cell stack 110 is... stk Below the second predetermined temperature T prd2 If the temperature T of fuel cell stack 110 is within the acceptable range, then fuel cell stack 110 is considered to have no risk of overheating; conversely, if the fuel cell stack temperature T of fuel cell stack 110 is within the acceptable range, then fuel cell stack 110 is considered to have no risk of overheating. stk Higher than or equal to the second predetermined temperature T prd2 If the fuel cell stack 110 is considered to have an overheating risk, then the second predetermined temperature T is set. prd2 It can be set to the lowest temperature at which the fuel cell stack 110 is at risk of overheating.
[0052] Under the above configuration, in step S500, not only is the inflection point of the high-frequency impedance HFR from decreasing to increasing monitored, but also the stack temperature T of the fuel cell stack 110 is monitored. stk Furthermore, when the inflection point of the high-frequency impedance HFR from decreasing to increasing is detected, or when the stack temperature T is detected... stk Reaching the second predetermined temperature T prd2 When this occurs, step S600 is executed to start the coolant pump 150 and fan 162 to use coolant to help cool the fuel cell stack 110. That is, if the inflection point of the high-frequency impedance HFR from decreasing to increasing cannot be detected, then the cooling can be initiated when the fuel cell stack temperature T is monitored. stk Reaching the second predetermined temperature T prd2 At the same time, a thermal management system is used to help cool the fuel cell stack 110, thereby preventing overheating and ensuring the safety and reliability of both the fuel cell stack 110 and the fuel cell 100. Specifically, due to the first predetermined temperature T... prd1 Used to determine whether the fuel cell stack 110 is in a low-temperature environment or a normal-temperature environment, while the second predetermined temperature T prd2 Used to determine whether the fuel cell stack 110 is at risk of overheating, therefore the second predetermined temperature T prd2 It can be set to a temperature higher than the first predetermined temperature T. prd1 For example, it can be set to 50℃, 60℃, 70℃, 80℃, etc.
[0053] According to an optional implementation, step S300 involves: starting the coolant pump 150 and the fan 162, and driving the coolant at a rated flow rate V. ctr The coolant flows in the coolant circulation line L1, that is, the coolant flows at the rated flow rate V. ctr The coolant circulates through the fuel cell stack 110 and the radiator 161. Under this configuration, without requiring the implementation of the cold start strategy according to this disclosure, that is, during normal startup of the fuel cell stack 110, the coolant is kept at a rated flow rate V. ctr The coolant is circulated to ensure efficient cooling of the fuel cell stack 110. Specifically, this can be achieved by operating the coolant pump 150 at its rated speed to ensure a rated coolant flow rate V. ctr The coolant flows in the coolant circulation line L1. Specifically, step S600 also involves: starting the coolant pump 150 and fan 162, and driving the coolant at a rated flow rate V. ctr The coolant flows in the coolant circulation line L1, that is, the coolant flows at the rated flow rate V. ctr The coolant circulates through the fuel cell stack 110 and the radiator 161. Under the above configuration, when implementing the cold start strategy according to this disclosure, that is, during a cold start of the fuel cell stack 110, if an inflection point where the high-frequency impedance changes from decreasing to increasing is detected, the coolant is also kept at a rated flow rate V. ctrThe flow ensures that the stack 110 can be cooled efficiently, thereby more reliably maintaining the high-frequency impedance (HFR) at a low level, thus more reliably improving the efficiency of the electrochemical reaction and improving the performance of the fuel cell.
[0054] refer to Figure 3 The diagram illustrates a schematic flowchart of a method for starting a fuel cell according to another embodiment of the present disclosure. Figure 3 As shown, the method further includes the following steps after step S600:
[0055] S700: Set the stack temperature T of fuel cell stack 110. stk With the third predetermined temperature T prd3 For comparison, if the stack temperature T stk Below the third predetermined temperature T prd3 If the stack temperature T is..., then proceed to step S800; stk Higher than or equal to the third predetermined temperature T prd3 Then proceed to step S900;
[0056] S800: Allows the coolant to flow at a predetermined rate V ctp The coolant flows in the coolant circulation line L1, that is, the coolant is made to flow at a predetermined flow rate V. ctp The fluid circulates through the fuel cell stack 110 and the heat sink 161, and returns to step S700; and
[0057] S900: Allows the coolant to flow at a rated rate V ctr The coolant flows in the coolant circulation line L1, that is, the coolant flows at the rated flow rate V. ctr The fluid circulates through the fuel cell stack 110 and the radiator 161, wherein the rated flow velocity V ctr greater than the predetermined flow rate V ctp .
[0058] Specifically, the third predetermined temperature T prd3 The stack temperature T can be set to define the stack 110. stk Whether the suitable operating temperature has been reached, that is, if the fuel cell stack temperature T of fuel cell stack 110 is... stk Below the third predetermined temperature T prd3 Therefore, the stack temperature T of the fuel cell stack 110 is considered to be... stk The suitable operating temperature has not yet been reached; if the fuel cell stack temperature T of fuel cell stack 110... stk Higher than or equal to the third predetermined temperature T prd3 Therefore, the stack temperature T of the fuel cell stack 110 is considered to be... stk The suitable operating temperature has been reached; therefore, the third predetermined temperature T... prd3This can be set to the lower limit of the suitable operating temperature range for the fuel cell stack 110. Specifically, due to the third predetermined temperature T... prd3 The stack temperature T used to define stack 110 stk Whether the suitable operating temperature has been reached, therefore the third predetermined temperature T prd3 It can be set to a temperature higher than the first predetermined temperature T. prd1 And below the second predetermined temperature T prd2 .
[0059] Specifically, the coolant can be supplied at a flow rate V less than the rated speed by operating the coolant pump 150 at a predetermined speed less than the rated speed. ctr The predetermined flow rate V ctp It flows in the coolant circulation line L1.
[0060] Under the above configuration, after performing step S600 to start the coolant pump 150 and fan 162, step S700 is performed to determine the stack temperature T. stk Has the third predetermined temperature T been reached? prd3 If the stack temperature T stk The third predetermined temperature T has not yet been reached. prd3 This indicates that the stack temperature T stk If the suitable operating temperature has not yet been reached, then in step S800, the coolant is allowed to flow at a rate less than the rated flow rate V. ctr The predetermined flow rate V ctp The coolant flows in the coolant circulation line L1, allowing the coolant to flow at the rated velocity V. ctr Compared to flowing in the coolant circulation line L1, this can slow down the cooling of the fuel cell stack 110 by the coolant, so that the stack temperature T of the fuel cell stack 110 is lowered. stk It can rise to the suitable operating temperature more quickly, thus enabling the fuel cell stack 110 to start up more quickly; if the fuel cell stack temperature T stk The third predetermined temperature T has been reached. prd3 This indicates that the stack temperature T stk Once the suitable operating temperature has been reached, in step S900, the coolant is allowed to flow at the rated flow rate V. ctr The coolant flows in the coolant circulation line L1 to enable efficient cooling of the fuel cell stack 110. Therefore, the above configuration not only maintains the high-frequency impedance of the fuel cell stack at a low level during cold start-up, but also ensures a fast start-up speed.
[0061] The foregoing has described in detail, with reference to the accompanying drawings, alternative but non-limiting embodiments of the method for starting a fuel cell according to the present disclosure. Modifications and additions to the technology and structure, as well as recombinations of features in the various embodiments, should be considered within the scope of this disclosure without departing from its spirit and essence. Therefore, such modifications and additions conceivable under the teachings of this disclosure should be considered part of this disclosure. The scope of this disclosure includes equivalent technologies known at the filing date of this disclosure and equivalent technologies not yet foreseen.
Claims
1. A method for starting a fuel cell, said fuel cell (100) comprising a stack (110) and a coolant circulation line (L1), said coolant circulation line (L1) supplying coolant to the stack (110) through a coolant inlet (110) of the fuel cell. i ) and coolant outlet (110 o The method includes the following steps: S100: Supply cathode gas and anode gas to the fuel cell stack (110), and detect the fuel cell stack temperature T of the fuel cell stack (110). stk ; S200: Set the stack temperature T stk With the first predetermined temperature T prd1 Compare, if T stk ≥T prd1 If T stk <T prd1 If so, then execute S400; S300: Drives the coolant to flow in the coolant circulation line (L1); S400: According to the predetermined time series t0, t1, ..., t n The high-frequency impedance HFR of the fuel cell stack (110) was detected; S5 00: Will be at time t i+1 Detected high-frequency impedance HFR i+1 With at time t i Detected high-frequency impedance HFR i Compare, if HFR i+1 <HFR i If so, return S400; if HFR i+1 ≥HFR i Then execute S600, where i = 0, 1, 2, ..., n; and S600: Drives the coolant to flow in the coolant circulation line (L1).
2. A method for starting a fuel cell, the fuel cell (100) comprising a stack (110) and a coolant circulation line (L1), the coolant circulation line (L1) supplying the coolant inlet (110) of the stack (110) to the fuel cell. i ) and coolant outlet (110 o The method includes the following steps: S100: Supply cathode gas and anode gas to the fuel cell stack (110), and detect the fuel cell stack temperature T of the fuel cell stack (110). stk ; S200: Set the stack temperature T stk With the first predetermined temperature T prd1 Compare, if T stk ≥T prd1 If T stk <T prd1 If so, then execute S400; S300: Drives the coolant to flow in the coolant circulation line (L1); S400: According to the predetermined time series t0, t1, ..., t n The high-frequency impedance HFR of the fuel cell stack (110) was detected; S5 00: Set the stack temperature T stk With the second predetermined temperature T prd2 Compare, and at time t i+1 Detected high-frequency impedance HFR i+1 With at time t i Detected high-frequency impedance HFR i Compare, if T stk <T prd2 And HFR i+1 <HFR i If T stk ≥T prd2 Or HFR i+1 ≥HFR i Then execute S600, where i = 0, 1, 2, ..., n; and S600: Drives the coolant to flow in the coolant circulation line (L1).
3. The method according to claim 2, wherein, First predetermined temperature T prd1 With the second predetermined temperature T prd2 Set to make T prd1 <T prd2 .
4. A method for starting a fuel cell, the fuel cell (100) comprising a stack (110) and a coolant circulation line (L1), the coolant circulation line (L1) supplying the coolant inlet (110) of the stack (110) to the fuel cell. i ) and coolant outlet (110 o The method includes the following steps: S100: Supply cathode gas and anode gas to the fuel cell stack (110), and detect the fuel cell stack temperature T of the fuel cell stack (110). stk ; S200: Set the stack temperature T stk With the first predetermined temperature T prd1 Compare, if T stk ≥T prd1 If T stk <T prd1 If so, then execute S400; S300: Drives the coolant to flow in the coolant circulation line (L1); S400: According to the predetermined time series t0, t1, ..., t n The high-frequency impedance HFR of the fuel cell stack (110) was detected; S5 00: Will be at time t i+1 Detected high-frequency impedance HFR i+1 With at time t i Detected high-frequency impedance HFR i Compare, and at time t i+2 Detected high-frequency impedance HFR i+2 With at time t i+1 Detected high-frequency impedance HFR i+1 Compare, if HFR i+1 <HFR i Or HFR i+2 <HFR i+1 If so, return S400; if HFR i+1 ≥HFR i And HFR i+2 ≥HFR i+1 Then execute S600, where i = 0, 1, 2, ..., n; and S600: Drives the coolant to flow in the coolant circulation line (L1).
5. The method according to any one of claims 1-4, wherein, S300 is characterized by: driving the coolant at a rated flow rate V ctr It flows in the coolant circulation line (L1).
6. The method according to claim 5, wherein, S600 is characterized by: driving the coolant at a rated flow rate V ctr It flows in the coolant circulation line (L1).
7. The method according to claim 5, wherein, The method further includes the following steps after S600: S700: Set the stack temperature T stk With the third predetermined temperature T prd3 Compare, if T stk <T prd3 If T stk ≥T prd3 If so, then execute S900; S800: Allows the coolant to flow at a predetermined rate V ctp It flows in the coolant circulation line (L1) and returns to S700; and S900: Allows the coolant to flow at a rated rate V ctr Flowing in the coolant circulation line (L1), wherein V ctr >V ctD .
8. The method according to claim 7, wherein, First predetermined temperature T prd1 With the third predetermined temperature T prd3 Set to make T prd1 <T prd3 .
9. The method according to any one of claims 1-4, wherein, Stack temperature T stk It is one of the following parameters: at the coolant inlet (110) i The coolant inlet temperature T measured at point ) cti At the coolant outlet (110) o The coolant outlet temperature T measured at point ) cto Or the coolant inlet temperature T cti With coolant outlet temperature T cto The average value.
10. The method according to any one of claims 1-4, wherein, Predetermined time series t0, t1, ..., t n The time interval Δt between adjacent times in the time interval is fixed, so that t i+1 =t i +Δt, where i = 0, 1, 2, ..., n.