Low-temperature startup method, device, vehicle, and storage medium for fuel cell stack

Abstract

The present invention relates to a low-temperature starting method, device, vehicle and storage medium for a fuel cell stack. The method comprises: determining whether a current fuel cell stack has a low-temperature starting requirement; if the current fuel cell stack has a low-temperature starting requirement, obtaining the current voltage of the current fuel cell stack, and when the current voltage is greater than or equal to a first preset voltage, reducing the cathode stoichiometric ratio of the current fuel cell stack according to a preset reduction strategy, and obtaining the lowest single-chip voltage and coolant temperature of the current fuel cell stack during the process of reducing the cathode stoichiometric ratio; determining the current starting stoichiometric ratio of the current fuel cell stack according to the lowest single-chip voltage and coolant temperature of the current fuel cell stack, and starting the current fuel cell stack according to the current starting stoichiometric ratio. Thus, by precisely coupling the influence of the fuel cell hydrogen permeation current and polarization impedance, the fuel cell stack cathode stoichiometric ratio and fuel cell heat generation are precisely controlled, thereby significantly improving the vehicle's low-temperature starting success rate and increasing the service life of the fuel cell.

Description

Technical Field

[0001] The present invention relates to the field of fuel cell technology, and in particular to a low-temperature starting method, device, vehicle and storage medium for a fuel cell stack. Background Art

[0002] Fuel cells operate by generating electricity, water, and heat through an electrochemical reaction between hydrogen and oxygen. As a product of this electrochemical reaction, water serves as both the medium for proton transfer during fuel cell power generation and the primary barrier to the transmission of hydrogen and oxygen gases. When a fuel cell is started at or below freezing, the water product freezes during startup, preventing the reactant gases from reaching the catalyst surface for the electrochemical reaction. If this freezing completely blocks the gas reaction pathway, low-temperature startup failure can result. Furthermore, freezing damages the fuel cell's membrane electrode, shortening its lifespan.

[0003] In related technologies, when the fuel cell stack is started at low temperature, the external output power of the fuel cell is generally lowered by reducing the air flow, converting more fuel cell chemical energy into heat energy for heating the fuel cell, and eliminating the adverse effects of ice crystals in the fuel cell flow path on the fuel cell operation as soon as possible.

[0004] However, since this method fails to accurately determine the cathode stoichiometric ratio during low-temperature startup of the fuel cell stack, it is easy for uneven gas distribution or local temperature differences to cause some single chips to be in a state of low performance or reverse polarity for a long time. This not only leads to a low success rate for low-temperature startup of the vehicle, but also greatly reduces the life of the fuel cell, which urgently needs to be solved. Summary of the Invention

[0005] The present invention provides a low-temperature start-up method, device, vehicle, and storage medium for a fuel cell stack to solve the problem in the related art that the cathode stoichiometric ratio of the fuel cell stack cannot be accurately determined during low-temperature start-up, which easily causes some single chips to be in a low performance or reverse polarity state for a long time due to uneven gas distribution or local temperature differences. This not only leads to a low low-temperature start success rate for the vehicle, but also greatly reduces the life of the fuel cell. Under the influence of the precise coupling of the fuel cell hydrogen permeation current and polarization impedance, the fuel cell stack cathode stoichiometric ratio and the fuel cell heat generation are accurately controlled, which greatly improves the low-temperature start success rate of the vehicle and increases the service life of the fuel cell.

[0006] To achieve the above objectives, a first embodiment of the present invention provides a low-temperature startup method for a fuel cell stack, comprising the following steps:

[0007] Determine whether the current stack needs to be started at low temperature;

[0008] If the current fuel cell stack has the low-temperature startup requirement, obtaining the current voltage of the current fuel cell stack, and when the current voltage is greater than or equal to a first preset voltage, reducing the cathode stoichiometric ratio of the current fuel cell stack according to a preset reduction strategy, and obtaining the lowest single-chip voltage and coolant temperature of the current fuel cell stack during the process of reducing the cathode stoichiometric ratio;

[0009] A current startup metering ratio of the current fuel cell stack is determined according to the lowest single-chip voltage of the current fuel cell stack and the coolant temperature, and the current fuel cell stack is started according to the current startup metering ratio.

[0010] According to one embodiment of the present invention, determining the current startup metering ratio of the current fuel cell stack according to the lowest single-chip voltage of the current fuel cell stack and the coolant temperature includes:

[0011] Determining whether the minimum single-chip voltage is less than a second preset voltage;

[0012] If the lowest single-chip voltage is less than the second preset voltage, the metering ratio when the lowest single-chip voltage is less than the second preset voltage is used as the current startup metering ratio; otherwise, determining whether the coolant temperature is greater than a preset temperature;

[0013] If the coolant temperature is greater than the preset temperature, the preset startup metering ratio is used as the current startup metering ratio.

[0014] According to one embodiment of the present invention, reducing the cathode stoichiometric ratio of the current fuel cell stack according to a preset reduction strategy includes:

[0015] reducing the cathode stoichiometric ratio of the current stack according to a first reduction rate, and determining, during the process of reducing the cathode stoichiometric ratio, whether the lowest single-cell voltage of the current stack is greater than or equal to a second preset voltage and whether the voltage of the current stack is reduced from the current voltage to a third preset voltage;

[0016] If, during the process of reducing the cathode stoichiometric ratio, the lowest single-cell voltage of the current stack is greater than or equal to the second preset voltage and the voltage of the current stack is reduced from the current voltage to the third preset voltage, the cathode stoichiometric ratio of the current stack is reduced at a second reduction rate until the lowest single-cell voltage of the current stack is less than the second preset voltage, and the reduction of the cathode stoichiometric ratio is stopped;

[0017] The second reduction rate is smaller than the first reduction rate, the first preset voltage is larger than the third preset voltage, and the third preset voltage is larger than the second preset voltage.

[0018] According to one embodiment of the present invention, after reducing the cathode stoichiometric ratio of the current fuel cell stack according to the first reduction rate, the method further includes:

[0019] During the process of reducing the cathode stoichiometric ratio, determining whether the lowest single-cell voltage of the current stack is less than the second preset voltage;

[0020] If, during the process of reducing the cathode stoichiometric ratio, the lowest single-cell voltage of the current fuel cell stack is less than the first preset voltage, the reduction of the cathode stoichiometric ratio is stopped.

[0021] According to an embodiment of the present invention, before determining that the current voltage is greater than or equal to the first preset voltage, the method further includes:

[0022] Based on a preset low-temperature starting temperature, the first preset voltage is obtained by calibrating the anode stoichiometric ratio and the cathode stoichiometric ratio during the stack startup process;

[0023] Based on a preset constant current method, a second preset voltage is obtained by calibrating the preset hydrogen permeation current, the anode stoichiometric ratio, and the cathode stoichiometric ratio during the stack startup process;

[0024] Based on the preset EIS electric current impedance spectroscopy method, the third preset voltage is obtained according to the temperature and polarization impedance calibration of the low-temperature shutdown process.

[0025] According to one embodiment of the present invention, after determining whether the current fuel cell stack has the low-temperature startup requirement, the method further includes:

[0026] If the current fuel cell stack does not have the low-temperature startup requirement, the current fuel cell stack is started according to the preset startup metering ratio.

[0027] According to one embodiment of the present invention, obtaining the lowest single-cell voltage and coolant temperature of the current fuel cell stack during the process of reducing the cathode stoichiometric ratio includes:

[0028] Calculating the heat generation of the current fuel cell stack during the process of reducing the cathode stoichiometric ratio;

[0029] Based on a mapping relationship between heat generation and coolant temperature, the coolant temperature is determined according to the current heat generation of the fuel cell stack.

[0030] According to the low-temperature startup method for a fuel cell stack proposed in an embodiment of the present invention, by determining the current state of the fuel cell stack and, when a low-temperature startup is required, controlling the reduction of the stack's cathode stoichiometric ratio based on the stack voltage and a preset reduction strategy, while simultaneously monitoring the coolant temperature. After the coolant temperature reaches a preset temperature, the reduction of the cathode stoichiometric ratio is stopped, and the corresponding fuel cell stack is started. Thus, by precisely determining the low-temperature startup reactant stoichiometric ratio through control coupling, the calorific value is accurately calculated, and the hydrogen permeation current density is controlled, ensuring that the stack's melting rate is greater than the freezing rate within the hydrogen safety boundary. This improves the success rate of low-temperature startups for fuel cell commercial vehicles, ensures a better user experience, and extends the life of the fuel cell.

[0031] To achieve the above-mentioned objectives, a second embodiment of the present invention provides a low-temperature starting device for a fuel cell stack, comprising:

[0032] A judgment module is used to determine whether the current fuel cell stack has a low-temperature startup requirement;

[0033] a reduction ratio module, configured to obtain a current voltage of the current stack if the current stack has the low-temperature startup requirement, and, when the current voltage is greater than or equal to a first preset voltage, reduce the cathode stoichiometric ratio of the current stack according to a preset reduction strategy, and obtain the lowest single-chip voltage and coolant temperature of the current stack during the cathode stoichiometric ratio reduction process;

[0034] A starting module is used to determine a current starting metering ratio of the current fuel cell stack according to the lowest single-chip voltage of the current fuel cell stack and the coolant temperature, and to start the current fuel cell stack according to the current starting metering ratio.

[0035] According to one embodiment of the present invention, the startup module is specifically configured to:

[0036] Determining whether the minimum single-chip voltage is less than a second preset voltage;

[0037] If the lowest single-chip voltage is less than the second preset voltage, the metering ratio when the lowest single-chip voltage is less than the second preset voltage is used as the current startup metering ratio; otherwise, determining whether the coolant temperature is greater than a preset temperature;

[0038] If the coolant temperature is greater than the preset temperature, the preset startup metering ratio is used as the current startup metering ratio.

[0039] According to one embodiment of the present invention, the reduction ratio module is specifically configured to:

[0040] reducing the cathode stoichiometric ratio of the current stack according to a first reduction rate, and determining, during the process of reducing the cathode stoichiometric ratio, whether the lowest single-cell voltage of the current stack is greater than or equal to a second preset voltage and whether the voltage of the current stack is reduced from the current voltage to a third preset voltage;

[0041] If, during the process of reducing the cathode stoichiometric ratio, the lowest single-cell voltage of the current stack is greater than or equal to the second preset voltage and the voltage of the current stack is reduced from the current voltage to the third preset voltage, the cathode stoichiometric ratio of the current stack is reduced at a second reduction rate until the lowest single-cell voltage of the current stack is less than the second preset voltage, and the reduction of the cathode stoichiometric ratio is stopped;

[0042] The second reduction rate is smaller than the first reduction rate, the first preset voltage is larger than the third preset voltage, and the third preset voltage is larger than the second preset voltage.

[0043] According to one embodiment of the present invention, after reducing the cathode stoichiometric ratio of the current stack according to the first reduction rate, the reduction ratio module is further configured to:

[0044] During the process of reducing the cathode stoichiometric ratio, determining whether the lowest single-cell voltage of the current stack is less than the second preset voltage;

[0045] If, during the process of reducing the cathode stoichiometric ratio, the lowest single-cell voltage of the current fuel cell stack is less than the first preset voltage, the reduction of the cathode stoichiometric ratio is stopped.

[0046] According to one embodiment of the present invention, before determining that the current voltage is greater than or equal to the first preset voltage, the reduction ratio module is further configured to:

[0047] Based on a preset low-temperature starting temperature, the first preset voltage is obtained by calibrating the anode stoichiometric ratio and the cathode stoichiometric ratio during the stack startup process;

[0048] The second preset voltage is obtained by calibrating the preset hydrogen permeation current, the anode stoichiometric ratio, and the cathode stoichiometric ratio during the stack startup process based on a preset constant current method;

[0049] Based on the preset EIS electric current impedance spectroscopy method, the third preset voltage is obtained according to the temperature and polarization impedance calibration of the low-temperature shutdown process.

[0050] According to one embodiment of the present invention, after determining whether the current fuel cell stack has the low-temperature startup requirement, the determination module is further configured to:

[0051] If the current fuel cell stack does not have the low-temperature startup requirement, the current fuel cell stack is started according to the preset startup metering ratio.

[0052] According to one embodiment of the present invention, the reduction ratio module is specifically configured to:

[0053] Calculating the heat generation of the current fuel cell stack during the process of reducing the cathode stoichiometric ratio;

[0054] Based on a mapping relationship between heat generation and coolant temperature, the coolant temperature is determined according to the current heat generation of the fuel cell stack.

[0055] The low-temperature starting device for a fuel cell stack, according to an embodiment of the present invention, determines the current state of the fuel cell stack. When a low-temperature start is required, it controls the reduction of the stack's cathode stoichiometric ratio based on the stack voltage and a preset reduction strategy, while simultaneously monitoring the coolant temperature. Once the coolant temperature reaches a preset temperature, the reduction of the cathode stoichiometric ratio is stopped, and the corresponding fuel cell stack is started. This precise coupling of the fuel cell hydrogen permeation current and polarization impedance allows precise control of the stack's cathode stoichiometric ratio and fuel cell heat generation, significantly improving the vehicle's low-temperature start success rate and extending the fuel cell's service life.

[0056] To achieve the above-mentioned objectives, a third embodiment of the present invention proposes a vehicle, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the low-temperature starting method of the fuel cell stack as described in the above-mentioned embodiment.

[0057] To achieve the above objectives, a fourth embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, which is executed by a processor to implement the low-temperature startup method of the fuel cell stack as described in the above embodiments.

[0058] To achieve the above objectives, a fifth embodiment of the present invention provides a computer program product, including a computer program, which, when executed by a processor, is used to implement the low-temperature startup method of the fuel cell stack as described in the above embodiments.

[0059] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0061] Figure 1 A flowchart of a low-temperature startup method for a fuel cell stack provided in one embodiment of the present invention;

[0062] Figure 2 This is a schematic diagram of the equivalent circuit of a fuel cell during the charging process;

[0063] Figure 3 A schematic diagram of a control strategy for a low-temperature startup method of a fuel cell stack according to a specific embodiment of the present invention;

[0064] Figure 4 This is a schematic flow chart of a low-temperature startup method for a fuel cell stack according to a specific embodiment of the present invention;

[0065] Figure 5This is a block diagram of a low-temperature starting device for a fuel cell stack according to one embodiment of the present invention;

[0066] Figure 6 A schematic structural diagram of a vehicle provided in an embodiment of the present invention.

[0067] Reference numerals:

[0068] 10- low temperature starting device of fuel cell stack, 100- judgment module, 200- reduction ratio module, 300- starting module, 601- memory, 602- processor, 603- communication interface. DETAILED DESCRIPTION

[0069] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but are not to be construed as limiting the present invention.

[0070] The following describes a low-temperature starting method, device, vehicle, and storage medium for a fuel cell stack according to an embodiment of the present invention with reference to the accompanying drawings. First, a low-temperature starting method for a fuel cell stack according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0071] In view of the fact that the cathode stoichiometric ratio of the stack cannot be accurately determined during the startup process in the background art, it is easy for some single chips to be in a low performance or reverse polarity state for a long time due to uneven gas distribution or local temperature differences, which not only leads to a low success rate of low-temperature startup of the vehicle, but also greatly reduces the life of the fuel cell. The present invention provides a low-temperature startup method for the stack. By judging the current state of the stack, when there is a low-temperature startup demand, the cathode stoichiometric ratio of the stack is controlled to be reduced according to the stack voltage and a preset reduction strategy, while monitoring the coolant temperature; after the coolant temperature reaches the preset temperature, the cathode stoichiometric ratio is stopped and the corresponding stack is started. Therefore, by accurately coupling the influence of the fuel cell hydrogen permeation current and polarization impedance, the cathode stoichiometric ratio of the stack and the heat generation of the fuel cell are accurately controlled, which greatly improves the success rate of the vehicle's low-temperature startup and increases the service life of the fuel cell.

[0072] Specifically, Figure 1 This is a flow chart of a low-temperature startup method for a fuel cell stack provided by one embodiment of the present invention.

[0073] like Figure 1 As shown, the low-temperature startup method of the fuel cell stack includes the following steps:

[0074] In step S101 , it is determined whether the current fuel cell stack has a low-temperature startup requirement.

[0075] Among them, the low-temperature starting requirement can be a restriction condition set by the user based on factors such as temperature. When the set condition is met, it is determined that the current battery stack has a low-temperature starting requirement. For example, when the ambient temperature is lower than the preset temperature threshold and the vehicle receives a start command, it is determined that the current battery stack has a low-temperature starting requirement.

[0076] Specifically, the embodiment of the present invention first needs to determine whether there is a low-temperature startup requirement in the current battery stack state, so a startup condition needs to be set. Only when the startup condition is met can subsequent operations on the battery stack be continued.

[0077] For example, since the present invention primarily addresses the low-temperature startup issue of a fuel cell stack, the condition for determining whether a low-temperature startup requirement exists can be set to an ambient temperature below zero degrees Celsius. A temperature sensor is installed on the vehicle to obtain the ambient temperature. When the current ambient temperature is below zero degrees Celsius, the water produced by the reaction will freeze during vehicle startup, hindering the vehicle's cold start. Therefore, to ensure the success rate of low-temperature startup, embodiments of the present application can determine whether a low-temperature startup requirement exists for the fuel cell stack in this situation.

[0078] It should be noted that the condition for determining whether there is a need for low-temperature startup can be a single factor or a combination of multiple factors, such as the ambient temperature being lower than the preset temperature and the pressure difference between the inlet and outlet of the fuel cell stack being less than a threshold. The present invention does not impose specific restrictions on this.

[0079] In step S102, if the current fuel cell stack has a low-temperature startup requirement, the current voltage of the current fuel cell stack is obtained, and when the current voltage is greater than or equal to the first preset voltage, the cathode metering ratio of the current fuel cell stack is reduced according to the preset reduction strategy, and the lowest single-chip voltage and coolant temperature of the current fuel cell stack are obtained during the process of reducing the cathode metering ratio.

[0080] The first preset voltage can be obtained according to a mapping of a preset low-temperature starting temperature, anode-cathode stoichiometric ratio and stack voltage.

[0081] Specifically, the present invention determines the mapping values ​​of the low-temperature starting temperature, the anode-cathode metering ratio and the stack voltage in advance through experiments, and selects the stack voltage threshold value corresponding to the low-temperature starting temperature condition in the experiment as the first preset voltage. When it is detected that the stack has a low-temperature starting requirement, the embodiment of the present invention can obtain the current voltage of the current stack through a voltmeter set in the circuit. If the current stack voltage is less than the first preset voltage, according to the aforementioned mapping relationship, it means that the corresponding stack anode and cathode metering are relatively low at this time, and it is difficult to meet the low-temperature starting conditions, and the vehicle is likely to break down. Therefore, the stack power generation power should be adjusted, the stack power generation efficiency and stack temperature should be improved, so that the melting speed of the stack within the safety boundary is greater than the freezing speed, so as to meet the low-temperature starting conditions.

[0082] In some embodiments, the cathode stoichiometric ratio of the current fuel cell stack is reduced according to a preset reduction strategy, including: reducing the cathode stoichiometric ratio of the current fuel cell stack according to a first reduction rate, and determining whether the lowest single-chip voltage of the current fuel cell stack is greater than or equal to a second preset voltage and whether the voltage of the current fuel cell stack is reduced from the current voltage to a third preset voltage during the process of reducing the cathode stoichiometric ratio; if the lowest single-chip voltage of the current fuel cell stack is greater than or equal to the second preset voltage and the voltage of the current fuel cell stack is reduced from the current voltage to the third preset voltage during the process of reducing the cathode stoichiometric ratio, reducing the cathode stoichiometric ratio of the current fuel cell stack according to the second reduction rate until the lowest single-chip voltage of the current fuel cell stack is less than the second preset voltage, and stopping reducing the cathode stoichiometric ratio;

[0083] The second reduction rate is smaller than the first reduction rate, the first preset voltage is larger than the third preset voltage, and the third preset voltage is larger than the second preset voltage.

[0084] Among them, the second preset voltage can be obtained based on the mapping relationship between the preset hydrogen permeation current and the anode and cathode stoichiometric ratio and the stack voltage during the stack startup process; the third preset voltage can be obtained based on the mapping relationship between the preset EIS AC impedance spectroscopy low-temperature shutdown process temperature, polarization impedance and the stack output voltage.

[0085] Specifically, the preset reduction strategy of one embodiment of the present invention first determines whether the current stack voltage is greater than or equal to a first preset voltage. If the current voltage is greater than or equal to the first preset voltage, it indicates that the current stack power is insufficient for low-temperature startup. At this time, the cathode stoichiometric ratio of the current stack is reduced according to the first reduction rate. While reducing the cathode stoichiometric ratio of the current stack at the first reduction rate, it is monitored whether the lowest single-chip voltage of the current stack is greater than or equal to the second preset voltage and whether the voltage of the current stack is reduced to a third preset voltage. When the lowest single-chip voltage of the current stack is greater than or equal to the second preset voltage and the voltage of the current stack is reduced to the third preset voltage, the cathode stoichiometric ratio of the current stack has met the minimum limit condition for low-temperature startup. At this time, the reduction rate of the cathode stoichiometric ratio is reduced, and the cathode stoichiometric ratio of the stack is continued to be reduced at the second reduction rate. At the same time, it is monitored whether the lowest single-chip voltage of the current stack is less than the second preset voltage. If the lowest single-chip voltage of the current stack is less than the second preset voltage, if the cathode stoichiometric ratio is further reduced, hydrogen leakage will occur. Therefore, after determining that the lowest single-chip voltage of the current stack is less than the second preset voltage, the reduction of the cathode stoichiometric ratio is stopped.

[0086] It should be noted that when the cathode stoichiometric ratio of the stack is reduced, the anode stoichiometric ratio of the stack will also be reduced. Since the anode stoichiometric ratio can be reduced as the cathode stoichiometric ratio is reduced, only one of the stoichiometric ratios needs to be considered to achieve the effect of improving the cold start of the fuel cell.

[0087] In addition, in some embodiments, the minimum single-chip voltage and coolant temperature of the current fuel cell stack are obtained during the process of reducing the cathode stoichiometric ratio, including: calculating the heat generation of the current fuel cell stack during the process of reducing the cathode stoichiometric ratio; and determining the coolant temperature according to the heat generation of the current fuel cell stack based on a mapping relationship between the heat generation and the coolant temperature.

[0088] Specifically, an embodiment of the present invention can preset a fuel cell stack heat generation algorithm through the FCCU (Fuel Cell Control Unit), which can calculate the current heat generation of the fuel cell stack based on the fuel cell stack properties, and determine the current coolant temperature based on the mapping relationship between the heat generation of the fuel cell stack and the coolant temperature.

[0089] In step S103 , the current startup metering ratio of the current fuel cell stack is determined according to the lowest single-chip voltage and coolant temperature of the current fuel cell stack, and the current fuel cell stack is started according to the current startup metering ratio.

[0090] Specifically, the coolant temperature is determined based on the mapping relationship between the heat generation of the aforementioned battery stack and the coolant temperature. When the current coolant temperature is greater than the preset temperature, the water vapor in the battery stack will not freeze under the action of the coolant, and the vehicle can be cold-started smoothly. At this time, it is only necessary to use the aforementioned preset battery stack heat generation algorithm to calculate the current battery stack's minimum single-chip voltage and coolant temperature to determine the current starting metering ratio of the current battery stack, and start the current battery stack with the current starting metering ratio.

[0091] Optionally, in some embodiments, the current startup metering ratio of the current fuel cell stack is determined based on the minimum single-chip voltage and coolant temperature of the current fuel cell stack, including: judging whether the minimum single-chip voltage is less than a second preset voltage; if the minimum single-chip voltage is less than the second preset voltage, then using the metering ratio when the minimum single-chip voltage is less than the second preset voltage as the current startup metering ratio, otherwise, judging whether the coolant temperature is greater than the preset temperature; if the coolant temperature is greater than the preset temperature, then using the preset startup metering ratio as the current startup metering ratio.

[0092] Among them, the preset temperature can be a temperature value calibrated by technicians in this field based on experiments, or it can be data obtained through a limited number of computer simulations, and no specific limitation is made here; the preset starting metering ratio can be the cathode metering ratio when the vehicle is started at normal temperature.

[0093] It should be noted that the second preset voltage is obtained based on the hydrogen permeation current, the anode stoichiometric ratio and the cathode stoichiometric ratio during the stack startup process. Its purpose is to monitor the stack voltage to operate within the hydrogen safety range and prevent hydrogen leakage.

[0094] Specifically, while reducing the cathode stoichiometric ratio, the single-chip voltage of the fuel cell stack is monitored. When the lowest single-chip voltage is less than the second preset voltage, continuing to reduce the stoichiometric ratio may cause hydrogen leakage, so the reduction of the stoichiometric ratio should be stopped, and the stoichiometric ratio corresponding to the current single-chip voltage should be used as the current starting stoichiometric ratio; if the single-chip voltage of the fuel cell stack is still greater than or equal to the second preset voltage, the coolant temperature is determined to be greater than the preset temperature based on the mapping relationship between heat production and coolant temperature. If the coolant temperature is greater than the preset temperature, the water vapor in the fuel cell stack will not freeze, and the vehicle can be cold-started smoothly. At this time, the preset starting stoichiometric ratio can be used as the current starting stoichiometric ratio to start the fuel cell stack.

[0095] Therefore, the present invention judges the current state of the fuel cell stack, and when the preset stoichiometric ratio start-up conditions are met, controls the reduction of the cathode stoichiometric ratio of the fuel cell stack according to the fuel cell stack voltage and the preset reduction strategy, while monitoring the coolant temperature; after the coolant temperature reaches the preset temperature, stops reducing the cathode stoichiometric ratio and starts the corresponding fuel cell stack.

[0096] Optionally, in some embodiments, after reducing the cathode stoichiometric ratio of the current fuel cell stack according to the first reduction rate, it also includes: determining whether the lowest single-chip voltage of the current fuel cell stack is less than a second preset voltage during the process of reducing the cathode stoichiometric ratio; if the lowest single-chip voltage of the current fuel cell stack is less than the second preset voltage during the process of reducing the cathode stoichiometric ratio, then stopping reducing the cathode stoichiometric ratio.

[0097] Specifically, in the process of reducing the cathode stoichiometric ratio of the current stack at a first reduction rate, when the lowest single-chip voltage of the current stack is less than a second preset voltage, continuing to reduce the cathode stoichiometric ratio will cause hydrogen leakage, and the reduction of the cathode stoichiometric ratio must be stopped immediately.

[0098] Therefore, the embodiment of the present application stops reducing the cathode stoichiometric ratio when the lowest single-chip voltage of the current stack is less than the second preset voltage, thereby greatly improving the safety of the startup process while ensuring rapid startup.

[0099] Optionally, in some embodiments, before determining that the current voltage is greater than or equal to the first preset voltage, it also includes: based on a preset low-temperature starting temperature, calibrating the anode stoichiometric ratio and cathode stoichiometric ratio of the stack startup process to obtain a first preset voltage; based on a preset constant current method, calibrating the preset hydrogen permeation current, the anode stoichiometric ratio and cathode stoichiometric ratio of the stack startup process to obtain a second preset voltage; based on a preset EIS AC impedance spectroscopy method, calibrating the temperature and polarization impedance of the low-temperature shutdown process to obtain a third preset voltage.

[0100] The hydrogen permeation current can be measured by the constant current method, which requires the measurement to be performed when the fuel cell is normally charged.

[0101] Specifically, the embodiment of the present application can be Figure 2 The equivalent circuit shown is used to calibrate the first preset voltage, wherein: Figure 2 Schematic diagram of the equivalent circuit of a fuel cell during the charging process. Figure 2 In the constant current charging process of the fuel cell circuit, when the voltage reaches any end point V from the starting point V0 t When the voltage range [V0,V t ] takes T, then the charge conservation equation is as follows (1):

[0102]

[0103] Among them, Q Pt-H is the charge consumed in the hydrogen desorption process, Q dl is the amount of charge consumed in the charging process of the double-layer capacitor, ig represents the current density of the constant current charging process, i e V (t) Indicates the internal short-circuit current density corresponding to the voltage V(t), i H2 It represents the hydrogen permeation current density.

[0104] In addition, the third preset voltage of the embodiment of the present invention is the value of the stack voltage in the mapping relationship between the temperature, the anode-cathode stoichiometric ratio and the stack voltage during low-temperature startup; the third preset voltage can be measured by using EIS AC impedance spectroscopy when the stack is shut down at low temperature. Specifically, it can be obtained by establishing a mapping relationship between the temperature, polarization impedance and the stack output voltage during the low-temperature shutdown process, wherein the stack output voltage is the third preset voltage. The stack output voltage calculation method is shown in the following formula (2):

[0105] V0=Vocv-IR HFR (2)

[0106] Wherein, V0 is the stack output voltage when the second preset voltage or the third preset voltage is calibrated, R HFR It is equivalent to the polarization impedance of the battery stack.

[0107] Optionally, in some embodiments, after determining whether the current fuel cell stack has a low-temperature startup requirement, the method further includes: if the current fuel cell stack does not have a low-temperature startup requirement, starting the current fuel cell stack according to a preset startup metering ratio.

[0108] Specifically, when there is no low-temperature starting requirement for the fuel cell stack, it means that the current vehicle can start normally and no additional metering ratio reduction operation is required. At this time, it is only necessary to start the fuel cell stack normally according to the preset starting metering ratio.

[0109] In order to enable those skilled in the art to further understand the low-temperature startup method of the fuel cell stack in the embodiment of the present application, it is described in detail below with reference to specific embodiments.

[0110] Specifically, if Figure 3 As shown, Figure 3 This is a schematic diagram of a control strategy for a low-temperature startup method of a fuel cell stack according to a specific embodiment of the present invention. The control strategy includes:

[0111] The stack heat generation algorithm is preset through the FCCU, and the mapping of the long stack hydrogen permeation current of the constant current method, the preset low-temperature starting temperature, the anode and cathode stoichiometric ratios and the stack voltage, the preset EIS AC impedance spectroscopy low-temperature shutdown process temperature, and the mapping of the polarization impedance and the stack output voltage are preset. The three mapping relationships are respectively input into the preset interpolation table: hydrogen stoichiometric ratio and the preset interpolation table: empty stoichiometric ratio; the output voltage and temperature of the fuel cell stack are monitored, and the stack temperature and the gas pressure in the stack are preset at the same time to eliminate the influence of temperature and gas pressure on the EIS control algorithm and retain only the stoichiometric ratio variable; when the conditions of the derating table are met, the cathode stoichiometric ratio of the fuel cell is controlled according to the preset interpolation table to ensure that the melting rate of the fuel cell within the hydrogen safety boundary is greater than the freezing rate, and when it is detected that the fuel cell voltage meets the end condition given by the control condition, the stoichiometric ratio reduction operation of the stack is terminated.

[0112] Furthermore, if Figure 4 As shown, Figure 4 This is a flow chart of a low-temperature startup method for a fuel cell stack according to a specific embodiment of the present invention, comprising the following steps:

[0113] S401 , based on a preset low-temperature starting temperature, calibrate a first preset voltage according to an anode stoichiometric ratio and a cathode stoichiometric ratio during a stack starting process.

[0114] S402 , based on a preset constant current method, calibrate and obtain a second preset voltage according to a preset hydrogen permeation current, an anode stoichiometric ratio, and a cathode stoichiometric ratio during the stack startup process.

[0115] S403 , based on a preset EIS electrochemical impedance spectroscopy method, calibrate and obtain a third preset voltage according to the temperature and polarization impedance of the low-temperature shutdown process.

[0116] S404, the fuel cell controller FCCU presets an EIS fitting algorithm to calculate in real time the mapping relationship between the stack voltage V0 and the temperature, anode, and cathode stoichiometric ratio during the operation of the stack.

[0117] S405: Determine if the stack voltage V0 is greater than or equal to the first preset voltage V1. If so, execute S406.

[0118] S406 , reducing the cathode stoichiometric ratio of the current fuel cell stack according to a first reduction rate, and obtaining the lowest single-chip voltage and coolant temperature of the current fuel cell stack during the process of reducing the cathode stoichiometric ratio.

[0119] S407 , determining whether the lowest single-chip voltage is greater than or equal to the second preset voltage V2 , if so, executing S408 ; if not, executing S410 .

[0120] S408, determine whether the coolant temperature is greater than a preset temperature, if yes, execute S411; if no, execute S409.

[0121] S409, when the voltage of the current stack is reduced from the current voltage to the third preset voltage, the cathode stoichiometric ratio of the current stack is reduced according to the second reduction rate, and in the process of reducing the cathode stoichiometric ratio, if the lowest single-chip voltage of the current stack is less than the second preset voltage, the stoichiometric ratio when the lowest single-chip voltage is less than the second preset voltage is used as the current starting stoichiometric ratio; otherwise, when the lowest single-chip voltage of the current stack is less than the second preset voltage, the cathode stoichiometric ratio is stopped from being reduced until the coolant temperature is greater than the preset temperature, and the preset starting stoichiometric ratio is used as the current starting stoichiometric ratio

[0122] S410 , taking the metering ratio when the lowest single-chip voltage is less than the second preset voltage as the current startup metering ratio.

[0123] S411: Using the preset startup metering ratio as the current startup metering ratio.

[0124] According to an embodiment of the present invention, the low-temperature startup method for a fuel cell stack determines the current state of the fuel cell stack. When a low-temperature startup is required, the stack's cathode stoichiometric ratio is reduced based on the stack voltage and a preset reduction strategy, while simultaneously monitoring the coolant temperature. Once the coolant temperature reaches a preset temperature, the reduction in the cathode stoichiometric ratio is stopped, and the corresponding fuel cell stack is started. This method, through the precise coupling of the fuel cell hydrogen permeation current and polarization impedance, accurately controls the stack's cathode stoichiometric ratio and fuel cell heat generation, significantly improving the vehicle's low-temperature startup success rate and extending the fuel cell's service life.

[0125] Next, a low-temperature starting device for a fuel cell stack according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0126] Figure 5 Schematic diagram of a low-temperature starting device for a fuel cell stack according to an embodiment of the present invention.

[0127] like Figure 5 As shown, the low-temperature starting device 10 of the fuel cell stack includes: a judgment module 100 , a reduction ratio module 200 and a starting module 300 .

[0128] The judgment module 100 is used to judge whether the current stack has a low-temperature startup requirement;

[0129] The reduction ratio module 200 obtains the current voltage of the current stack if the current stack has a low-temperature startup requirement, and when the current voltage is greater than or equal to a first preset voltage, reduces the cathode stoichiometric ratio of the current stack according to a preset reduction strategy, and obtains the lowest single-chip voltage and coolant temperature of the current stack during the cathode stoichiometric ratio reduction process;

[0130] The starting module 300 is used to determine the current starting metering ratio of the current fuel cell stack according to the lowest single-chip voltage and coolant temperature of the current fuel cell stack, and start the current fuel cell stack according to the current starting metering ratio.

[0131] According to one embodiment of the present invention, the starting module 300 is specifically used to: determine whether the lowest single-chip voltage is less than a second preset voltage; if the lowest single-chip voltage is less than the second preset voltage, then use the metering ratio when the lowest single-chip voltage is less than the second preset voltage as the current starting metering ratio; otherwise, determine whether the coolant temperature is greater than a preset temperature; if the coolant temperature is greater than the preset temperature, then use the preset starting metering ratio as the current starting metering ratio.

[0132] According to one embodiment of the present invention, the ratio reduction module 200 is specifically used to: reduce the cathode stoichiometric ratio of the current fuel cell stack according to a first reduction rate, and determine whether the lowest single-chip voltage of the current fuel cell stack is greater than or equal to the second preset voltage and whether the voltage of the current fuel cell stack is reduced from the current voltage to the third preset voltage during the process of reducing the cathode stoichiometric ratio; if the lowest single-chip voltage of the current fuel cell stack is greater than or equal to the second preset voltage and the voltage of the current fuel cell stack is reduced from the current voltage to the third preset voltage during the process of reducing the cathode stoichiometric ratio, reduce the cathode stoichiometric ratio of the current fuel cell stack according to the second reduction rate until the lowest single-chip voltage of the current fuel cell stack is less than the second preset voltage, and stop reducing the cathode stoichiometric ratio;

[0133] The second reduction rate is smaller than the first reduction rate, the first preset voltage is larger than the third preset voltage, and the third preset voltage is larger than the second preset voltage.

[0134] According to one embodiment of the present invention, after reducing the cathode stoichiometric ratio of the current fuel cell stack according to the first reduction rate, the reduction ratio module 200 is further used to: determine whether the lowest single-chip voltage of the current fuel cell stack is less than the second preset voltage during the process of reducing the cathode stoichiometric ratio; if the lowest single-chip voltage of the current fuel cell stack is less than the first preset voltage during the process of reducing the cathode stoichiometric ratio, stop reducing the cathode stoichiometric ratio.

[0135] According to one embodiment of the present invention, before determining that the current voltage is greater than or equal to the first preset voltage, the reduction ratio module 200 is further used to: based on the preset low-temperature starting temperature, calibrate the anode stoichiometric ratio and the cathode stoichiometric ratio of the fuel cell stack startup process to obtain the first preset voltage; based on the preset constant current method, calibrate the preset hydrogen permeation current, the anode stoichiometric ratio and the cathode stoichiometric ratio of the fuel cell stack startup process to obtain the second preset voltage; based on the preset EIS AC impedance spectroscopy method, calibrate the temperature and polarization impedance of the low-temperature shutdown process to obtain the third preset voltage.

[0136] According to one embodiment of the present invention, after determining whether the current fuel cell stack has a low-temperature startup requirement, the determination module 100 is further configured to: if the current fuel cell stack does not have a low-temperature startup requirement, start the current fuel cell stack according to a preset startup metering ratio.

[0137] According to one embodiment of the present invention, the reduction ratio module 200 is specifically used to: calculate the heat generation of the current fuel cell stack during the process of reducing the cathode stoichiometric ratio; and determine the coolant temperature according to the heat generation of the current fuel cell stack based on the mapping relationship between heat generation and coolant temperature.

[0138] The low-temperature starting device for a fuel cell stack, according to an embodiment of the present invention, determines the current state of the fuel cell stack. When a low-temperature start is required, it controls the reduction of the stack's cathode stoichiometric ratio based on the stack voltage and a preset reduction strategy, while simultaneously monitoring the coolant temperature. Once the coolant temperature reaches a preset temperature, the reduction of the cathode stoichiometric ratio is stopped, and the corresponding fuel cell stack is started. This precise coupling of the fuel cell hydrogen permeation current and polarization impedance allows precise control of the stack's cathode stoichiometric ratio and fuel cell heat generation, significantly improving the vehicle's low-temperature start success rate and extending the fuel cell's service life.

[0139] Figure 6 A schematic diagram of the structure of a vehicle provided in an embodiment of the present invention. The vehicle may include:

[0140] A memory 601 , a processor 602 , and a computer program stored in the memory 601 and executable on the processor 602 .

[0141] When the processor 602 executes the program, the low-temperature startup method of the fuel cell stack provided in the above embodiment is implemented.

[0142] Furthermore, the vehicle further comprises:

[0143] The communication interface 603 is used for communication between the memory 601 and the processor 602 .

[0144] The memory 601 is used to store computer programs that can be run on the processor 602 .

[0145] The memory 601 may include a high-speed RAM (Random Access Memory) memory, and may also include a non-volatile memory, such as at least one disk memory.

[0146] If the memory 601, the processor 602, and the communication interface 603 are implemented independently, the communication interface 603, the memory 601, and the processor 602 can be connected to each other via a bus and communicate with each other. The bus can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus, or an EISA (Extended Industry Standard Architecture) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 6 Only one thick line is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0147] Optionally, in a specific implementation, if the memory 601, the processor 602 and the communication interface 603 are integrated on a chip, the memory 601, the processor 602 and the communication interface 603 can communicate with each other through an internal interface.

[0148] The processor 602 may be a CPU (Central Processing Unit), or an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present invention.

[0149] An embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned low-temperature startup method of the fuel cell stack.

[0150] An embodiment of the present invention further provides a computer program product, including a computer program, which implements the above low-temperature startup method of the fuel cell stack when executed by a processor.

[0151] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0152] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0153] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A low-temperature startup method for a fuel cell stack, characterized in that: The following steps are involved: Determine whether the current stack needs to be started at low temperature; If the current fuel cell stack has the low-temperature startup requirement, obtaining the current voltage of the current fuel cell stack, and when the current voltage is greater than or equal to a first preset voltage, reducing the cathode stoichiometric ratio of the current fuel cell stack according to a preset reduction strategy, and obtaining the lowest single-chip voltage and coolant temperature of the current fuel cell stack during the process of reducing the cathode stoichiometric ratio; determining a current startup metering ratio of the current fuel cell stack according to the lowest single-chip voltage of the current fuel cell stack and the coolant temperature, and starting the current fuel cell stack according to the current startup metering ratio; Among them, the cathode stoichiometric ratio of the current fuel cell stack is reduced according to a preset reduction strategy, including: reducing the cathode stoichiometric ratio of the current fuel cell stack according to a first reduction rate, and judging whether the lowest single-chip voltage of the current fuel cell stack is greater than or equal to a second preset voltage and whether the voltage of the current fuel cell stack is reduced from the current voltage to a third preset voltage during the process of reducing the cathode stoichiometric ratio; if the lowest single-chip voltage of the current fuel cell stack is greater than or equal to the second preset voltage and the voltage of the current fuel cell stack is reduced from the current voltage to the third preset voltage during the process of reducing the cathode stoichiometric ratio, then reducing the cathode stoichiometric ratio of the current fuel cell stack according to a second reduction rate until the lowest single-chip voltage of the current fuel cell stack is less than the second preset voltage, and stopping reducing the cathode stoichiometric ratio; wherein, the second reduction rate is less than the first reduction rate, the first preset voltage is greater than the third preset voltage, and the third preset voltage is greater than the second preset voltage.

2. The method according to claim 1, characterized in that The determining the current startup metering ratio of the current fuel cell stack according to the lowest single-chip voltage of the current fuel cell stack and the coolant temperature includes: Determining whether the minimum single-chip voltage is less than a second preset voltage; If the lowest single-chip voltage is less than the second preset voltage, the metering ratio when the lowest single-chip voltage is less than the second preset voltage is used as the current startup metering ratio; otherwise, determining whether the coolant temperature is greater than a preset temperature; If the coolant temperature is greater than the preset temperature, the preset startup metering ratio is used as the current startup metering ratio.

3. The method according to claim 1, characterized in that After reducing the cathode stoichiometric ratio of the current fuel cell stack according to the first reduction rate, the method further includes: During the process of reducing the cathode stoichiometric ratio, determining whether the lowest single-cell voltage of the current stack is less than the second preset voltage; If, during the process of reducing the cathode stoichiometric ratio, the lowest single-cell voltage of the current fuel cell stack is less than the second preset voltage, the reduction of the cathode stoichiometric ratio is stopped.

4. The method according to claim 1, wherein Before determining that the current voltage is greater than or equal to the first preset voltage, the method further includes: Based on a preset low-temperature starting temperature, the first preset voltage is obtained by calibrating the anode stoichiometric ratio and the cathode stoichiometric ratio during the stack startup process; Based on a preset constant current method, a second preset voltage is obtained by calibrating the preset hydrogen permeation current, the anode stoichiometric ratio, and the cathode stoichiometric ratio during the stack startup process; Based on the preset EIS electric current impedance spectroscopy method, the third preset voltage is obtained according to the temperature and polarization impedance calibration of the low-temperature shutdown process.

5. The method according to claim 2, characterized in that After determining whether the current fuel cell stack has the low-temperature startup requirement, the method further includes: If the current fuel cell stack does not have the low-temperature startup requirement, the current fuel cell stack is started according to the preset startup metering ratio.

6. The method according to claim 1, characterized in that The obtaining of the lowest single-chip voltage and coolant temperature of the current stack during the process of reducing the cathode stoichiometric ratio includes: Calculating the heat generation of the current fuel cell stack during the process of reducing the cathode stoichiometric ratio; Based on a mapping relationship between heat generation and coolant temperature, the coolant temperature is determined according to the current heat generation of the fuel cell stack.

7. A low-temperature starting device for a fuel cell stack, characterized in that: include: A judgment module is used to determine whether the current fuel cell stack has a low-temperature startup requirement; an acquisition module, configured to, when the current stack has the low-temperature startup requirement, acquire the current voltage of the current stack, and, when the current voltage is greater than or equal to a first preset voltage, reduce the cathode stoichiometric ratio of the current stack according to a preset reduction strategy, and acquire the lowest single-chip voltage and coolant temperature of the current stack during the process of reducing the cathode stoichiometric ratio; a starting module, configured to determine a current starting metering ratio of the current fuel cell stack according to the lowest single-chip voltage of the current fuel cell stack and the coolant temperature, and start the current fuel cell stack according to the current starting metering ratio; Wherein, the acquisition module is used to: reduce the cathode metering ratio of the current fuel cell according to a first reduction rate, and judge whether the lowest single-chip voltage of the current fuel cell is greater than or equal to the second preset voltage and whether the voltage of the current fuel cell is reduced from the current voltage to the third preset voltage during the process of reducing the cathode metering ratio; if the lowest single-chip voltage of the current fuel cell is greater than or equal to the second preset voltage and the voltage of the current fuel cell is reduced from the current voltage to the third preset voltage during the process of reducing the cathode metering ratio, then reduce the cathode metering ratio of the current fuel cell according to the second reduction rate until the lowest single-chip voltage of the current fuel cell is less than the second preset voltage, and stop reducing the cathode metering ratio; wherein, the second reduction rate is less than the first reduction rate, the first preset voltage is greater than the third preset voltage, and the third preset voltage is greater than the second preset voltage.

8. A vehicle, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the low-temperature startup method for a fuel cell stack as claimed in any one of claims 1 to 6.

9. A computer storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the low-temperature starting method of the fuel cell stack as described in any one of claims 1 to 6.

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