Fuel cell low temperature starting method and device

Abstract

The present application discloses a fuel cell low-temperature start-up method and device, which determines the target fuel cell temperature of the fuel cell during the current moment of the fuel cell purge period, determines the target impedance corresponding to the target fuel cell temperature during the target purge period in a preset mapping relationship between the fuel cell temperature and impedance of the fuel cell during the purge period, purges the fuel cell until its impedance reaches the target impedance and stops, and controls the fuel cell to start at a preset target starting voltage at a low temperature. According to the mapping relationship between the impedance corresponding to the target fuel cell temperature during the target purge period and the residual water content, when the impedance of the fuel cell reaches the target impedance, the sum of the target residual water content of the fuel cell and the target water production generated by the temperature rising from the target starting low temperature to the target starting end temperature at the target starting voltage does not exceed the allowable water content of the fuel cell, thereby ensuring that the fuel cell can be successfully started at a low temperature at the target starting low temperature and any temperature above the target starting low temperature.

Description

Technical Field

[0001] The present application relates to the field of fuel cell technology, and more specifically, to a method and device for starting a fuel cell at low temperature. Background Art

[0002] Proton exchange membrane fuel cells (PEMFCs) are considered an ideal alternative for automotive powertrains due to their wide fuel supply, zero pollution, high efficiency, and fast startup response. Fuel cells operate through an electrochemical reaction between hydrogen and oxygen (air) to generate electricity, water, and heat. As a product of this electrochemical reaction, water serves as both a medium for proton transfer during fuel cell power generation and a major barrier to the transport of hydrogen and oxygen gases. When a fuel cell is started at or below freezing, the water produced by the electrochemical reaction freezes during startup, preventing the reactants from reaching the catalyst surface for the electrochemical reaction. Therefore, if the temperature of the fuel cell catalyst layer is not raised above freezing before the fuel cell interior completely freezes, cold-temperature startup failure will occur. Furthermore, ice formation can damage key fuel cell materials, causing permanent damage and shortening the fuel cell's lifespan. Therefore, to ensure a successful cold-temperature startup, the fuel cell is typically purged beforehand to reduce the residual water content within the fuel cell.

[0003] In practical applications, the end criterion for fuel cell shutdown purge is mainly based on the impedance of the fuel cell. During the purge process, as the residual water content inside the fuel cell decreases, the impedance of the fuel cell will increase, so the critical point where the impedance of the fuel cell enters the stable period from the rapid rise period is usually used as the end criterion for the purge. However, although this criterion can guide the purge process to a certain extent, it is impossible to accurately set the end criterion for the low-temperature start-up pre-purge and quantify the relationship between purge and low-temperature start-up, resulting in over-purge and under-purge during purge. Over-purge will not only lead to reduced hydrogen utilization and increased energy consumption, but may even cause subsequent fuel cell startup failure. Insufficient purge will cause excessive residual water content to squeeze the space for the electrochemical product water during the startup process, resulting in a decrease in instantaneous output performance and startup failure. Therefore, accurately setting the end criterion for the low-temperature start-up pre-purge has become a difficult point in the design of the low-temperature startup process of the fuel cell stack. Summary of the Invention

[0004] In view of this, the present application provides a fuel cell low-temperature start-up method and device for solving the existing fuel cell low-temperature start-up method. Since it is impossible to accurately set the end criterion of the pre-low-temperature start-up purge, it is impossible to determine the quantitative relationship between the purge and the low-temperature start-up, resulting in excessive purge and insufficient purge during purge, and the successful low-temperature start-up of the fuel cell cannot be guaranteed.

[0005] In order to achieve the above objectives, the following solutions are proposed:

[0006] A fuel cell low-temperature startup method, comprising:

[0007] determining a target fuel cell temperature during a purge period of the fuel cell at a current moment;

[0008] Determining a target impedance corresponding to the target fuel cell temperature during the purge period in a preset mapping relationship between the fuel cell temperature and the impedance during the purge period of the fuel cell;

[0009] The fuel cell is purged until the impedance of the fuel cell reaches the target impedance, and the purging is stopped, wherein, according to a mapping relationship between the impedance of the fuel cell and the residual water content corresponding to the fuel cell temperature during the target purge period, when the impedance of the fuel cell reaches the target impedance, the sum of the target residual water content of the fuel cell and the target water production generated by the fuel cell when the temperature rises from a preset target starting low temperature to a preset target starting end temperature at a preset target starting voltage does not exceed an allowable water content of the fuel cell, where the allowable water content is the amount of water corresponding to when the frozen area inside the fuel cell is completely frozen;

[0010] The fuel cell is controlled to start at a low temperature at the target starting voltage.

[0011] Preferably, the process of determining the mapping relationship between the fuel cell temperature and the impedance during the fuel cell purge period includes:

[0012] Determining the target starting voltage during the low-temperature starting process of the fuel cell;

[0013] Calculating a target heat output required for the fuel cell to be heated from the target startup low temperature to the target startup end temperature;

[0014] calculating, based on the target starting voltage, the target water production amount generated when the fuel cell generates the target heat production;

[0015] determining the allowable moisture content;

[0016] Subtracting the target water production from the allowable water content to obtain the target residual water content;

[0017] determining each impedance corresponding to the target residual water content according to a mapping relationship between the impedance of the fuel cell corresponding to the fuel cell temperature during each preset purge period and the residual water content;

[0018] A mapping relationship between the fuel cell temperature during each purge period and each impedance corresponding to the target residual water content is established.

[0019] Preferably, determining the target starting voltage during the low-temperature starting process of the fuel cell includes:

[0020] Determining the target power generation during the low-temperature startup of the fuel cell according to the preset idle power required for the low-temperature startup of the fuel cell;

[0021] Determining the target heating power during the low-temperature startup of the fuel cell according to the preset heating power required for the fuel cell to heat up from the target startup low temperature to the target startup end temperature;

[0022] A target starting voltage corresponding to when the fuel cell meets the target power generation power and the target heat generation power during low-temperature starting is determined.

[0023] Preferably, determining the allowable moisture content comprises:

[0024] obtaining a first residual water content of the fuel cell when the fuel cell is purged to a preset time;

[0025] obtaining a first water production amount generated by the fuel cell when the residual water content of the fuel cell is the first residual water content and the fuel cell is started at the target starting low temperature, resulting in the freezing area being completely frozen;

[0026] The sum of the first residual water content and the first water production is calculated to obtain the allowable water content.

[0027] Preferably, the obtaining of the first residual water content of the fuel cell when the fuel cell is purged to a preset time includes:

[0028] obtaining a first impedance of the fuel cell when the fuel cell is purged to a preset time according to a preset fuel cell temperature during a first purge period;

[0029] In the mapping relationship between the impedance of the fuel cell corresponding to the fuel cell temperature during the first purge period and the residual water content, a first residual water content corresponding to the first impedance is determined.

[0030] Preferably, obtaining the first water production generated by the fuel cell when the residual water content of the fuel cell is the first residual water content and the fuel cell is started at the target starting low temperature, resulting in the freezing area being completely frozen, includes:

[0031] Starting the fuel cell having the first residual water content at the target starting low temperature, and continuously introducing a constant-low-temperature antifreeze solution into the fuel cell starting at the target starting low temperature, wherein the temperature of the constant-low-temperature antifreeze solution is the target starting low temperature;

[0032] Loading the fuel cell that starts to start at the target starting low temperature, and collecting the current of the fuel cell in real time until the voltage of the fuel cell drops to a cut-off voltage or the current drops to a cut-off current;

[0033] Determine the function of current change over time based on the current collected in real time (t);

[0034] The first water production generated by the fuel cell when the fuel cell starts to start at the target starting low temperature and the freezing area is completely frozen is calculated based on the following formula: :

[0035] ;

[0036] Where F is the Faraday constant, M H2O is the molar mass of water, is the power generation area of the fuel cell.

[0037] Preferably, the process of determining the mapping relationship between the impedance of the fuel cell and the residual water content corresponding to the fuel cell temperature during each purge period includes:

[0038] determining a first weight of the fuel cell in a dry state;

[0039] Purging the fuel cell that has been running until a preset time according to a preset fuel cell temperature during each purge period until a preset time, and recording the impedance and the second weight of the fuel cell in real time during the purge of the fuel cell that has been running until the preset time, to obtain the impedance and the second weight of the fuel cell at different times at the fuel cell temperature during each purge period;

[0040] Subtracting the first weight from the second weight of the fuel cell at different times under the fuel cell temperature during each purge period to obtain the residual water content of the fuel cell at different times under the fuel cell temperature during each purge period;

[0041] A mapping relationship between the impedance and residual water content of the fuel cell corresponding to the fuel cell temperature during each purge period is established according to the impedance and residual water content of the fuel cell at different times during the fuel cell temperature during each purge period.

[0042] Preferably, calculating the target heat production required for the fuel cell to be heated from the target startup low temperature to the target startup end temperature includes:

[0043] Calculate the average heat capacity of the fuel cell ;

[0044] Calculate the target heat generation required for the fuel cell to rise from the target startup low temperature to the target startup end temperature ,in, is the target start end temperature, activating cryogenic temperatures for said target, is the power generation area of the fuel cell.

[0045] Preferably, the average heat capacity of the fuel cell is calculated ,include:

[0046] Determining the mass and mass specific heat capacity of each component constituting the fuel cell;

[0047] Calculating the product of the mass of each component and the mass specific heat capacity to obtain the average heat capacity of each component;

[0048] Calculate the sum of the average heat capacity of each component to obtain the average heat capacity of the fuel cell .

[0049] Preferably, calculating the target water production amount generated when the fuel cell generates the target heat production based on the target starting voltage includes:

[0050] The target water production generated when the fuel cell generates the target heat production is calculated based on the following formula

[0051] ;

[0052] in, is the theoretical voltage corresponding to the low calorific value, is the target starting voltage, F is the Faraday constant, M H2O is the molar mass of water, Produce heat for the target.

[0053] A fuel cell low-temperature starting device, comprising:

[0054] a temperature determination unit, configured to determine a target fuel cell purge period fuel cell temperature at a current moment;

[0055] a target impedance determining unit, configured to determine a target impedance corresponding to the target fuel cell temperature during the purge period in a preset mapping relationship between the fuel cell temperature and the impedance during the purge period of the fuel cell;

[0056] a purge unit configured to purge the fuel cell until the impedance of the fuel cell reaches the target impedance, and then stop the purge; wherein, according to a mapping relationship between the impedance of the fuel cell and the residual water content corresponding to the fuel cell temperature during the target purge period, when the impedance of the fuel cell reaches the target impedance, a sum of the target residual water content of the fuel cell and a target water production amount generated by the fuel cell when the temperature rises from a preset target starting low temperature to a preset target starting end temperature at a preset target starting voltage does not exceed an allowable water content of the fuel cell, where the allowable water content is the amount of water corresponding to when an internal frozen region of the fuel cell is completely frozen;

[0057] A control starting unit is used to control the fuel cell to start at a low temperature under the target starting voltage.

[0058] As can be seen from the above technical solutions, the fuel cell low-temperature startup method provided in the embodiments of the present application determines a target impedance corresponding to the fuel cell's current target fuel cell temperature during the purge period, based on a mapping relationship between the fuel cell temperature and impedance established in the present application. The method then purges the fuel cell until the fuel cell impedance reaches the target impedance, at which point the purge is stopped, and the fuel cell is controlled to start at a preset target starting voltage at a low temperature. Furthermore, based on the mapping relationship between the fuel cell impedance corresponding to the fuel cell temperature during the purge period and the residual water content, when the fuel cell impedance reaches the target impedance, the sum of the target residual water content and the target water production generated by the fuel cell when the temperature rises from the target starting low temperature to the target starting end temperature at the target starting voltage does not exceed the allowable water content of the fuel cell. Therefore, when the residual water content of the fuel cell reaches the target residual water content, if the fuel cell is started from the target starting low temperature at the target starting voltage, the water content within the fuel cell does not exceed the allowable water content, and the frozen area within the fuel cell will not completely freeze, thereby not completely blocking the reactant gases from reaching the catalyst surface for electrochemical reactions. If the fuel cell is started at a temperature above the target starting low temperature at the target starting voltage, the water content in the fuel cell will not exceed the allowable water content during the process of rising from the starting temperature to the target starting end temperature. The frozen area inside the fuel cell will not completely freeze, and the fuel cell will start successfully. By precisely setting the end criteria for the low-temperature start pre-purge, the problems of insufficient and excessive purge are avoided, ensuring that the fuel cell can successfully start at or above the target starting low temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without any creative work.

[0060] Figure 1 This is a flow chart of a low-temperature startup method for a fuel cell disclosed in an embodiment of the present application;

[0061] Figure 2 A flowchart of a process for determining a mapping relationship between fuel cell temperature and impedance during a fuel cell purge period disclosed in an embodiment of the present application;

[0062] Figure 3 This is a schematic diagram of a reasonable range of water production during low-temperature startup of a fuel cell disclosed in an embodiment of the present application;

[0063] Figure 4 This is a schematic structural diagram of a low-temperature starting device for a fuel cell disclosed in an embodiment of the present application;

[0064] Figure 5 This is a hardware structure block diagram of a fuel cell low-temperature starting device disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0065] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0066] This application provides a low-temperature start-up solution for fuel cells, which can be applied to proton exchange membrane fuel cells. Figure 1 The low temperature start-up method of the fuel cell of the present application is described as follows: Figure 1 As shown, the method may include:

[0067] Step S100: Determine the target fuel cell temperature during the purge period of the fuel cell at the current moment.

[0068] Specifically, considering that the end time of fuel cell purging is different when the fuel cell temperature is different, the target fuel cell temperature during purging is determined first. The target fuel cell temperature during purging is the current temperature of the fuel cell.

[0069] Step S110 : determining a target impedance corresponding to the target fuel cell temperature during the purge period in a preset mapping relationship between the fuel cell temperature and the impedance during the purge period of the fuel cell.

[0070] Specifically, the embodiment of the present application presets a mapping relationship between the fuel cell temperature and impedance during the fuel cell purge period, in which the target impedance corresponding to the fuel cell temperature during the target purge period is determined. The target impedance is the impedance of the fuel cell at the end of the fuel cell purge.

[0071] Step S120: Purge the fuel cell until the impedance of the fuel cell reaches the target impedance, and then stop the purge. According to a mapping relationship between the impedance of the fuel cell and the residual water content corresponding to the fuel cell temperature during the target purge period, when the impedance of the fuel cell reaches the target impedance, a sum of the target residual water content of the fuel cell and a target water production amount generated by the fuel cell when the temperature rises from a preset target starting low temperature to a preset target starting end temperature at a preset target starting voltage does not exceed an allowable water content of the fuel cell. The allowable water content is the amount of water corresponding to when the frozen area inside the fuel cell is completely frozen.

[0072] Specifically, the low-temperature start-up of a fuel cell refers to the process in which the fuel cell is raised from a cold state below 0°C to a hot state above 0°C to meet normal use by relying on the heat generated by the electrochemical reaction. Since there is a small amount of residual water inside the fuel cell after purging, and the electrochemical reaction also generates water, when starting from below the freezing point, the residual water inside the fuel cell and the generated water will freeze. If the ice area inside the fuel cell is completely frozen before the temperature of the catalytic layer of the fuel cell rises to the start-up end temperature, the low-temperature start-up of the fuel cell fails. Among them, the starting low temperature may be any temperature at or below 0°C, and the start-up end temperature is generally a temperature above 0°C and close to 0°C, such as 2°C. Therefore, before controlling the fuel cell to start the low-temperature start-up, the fuel cell is first purged to blow out some of the residual water inside the fuel cell to reduce the residual water content of the fuel cell. When the impedance of the fuel cell reaches the target impedance, the purge is stopped. This embodiment of the present application also presets a mapping relationship between the impedance of the fuel cell and the residual water content corresponding to the fuel cell temperature during the target purge period. According to this mapping relationship, when the impedance of the fuel cell reaches the target impedance, the sum of the target residual water content of the fuel cell and the target water production generated by the fuel cell when the temperature is raised from a preset target starting low temperature to a preset target starting end temperature at a preset target starting voltage does not exceed the allowable water content of the fuel cell. That is, when the fuel cell is purged to a residual water content reaching the target residual water content, if the fuel cell is started at the target starting low temperature at the target starting voltage, the amount of water in the fuel cell will not exceed the allowable water content. If the fuel cell is started at a temperature above the target starting low temperature at the target starting voltage, the amount of water in the fuel cell will also not exceed the allowable water content during the process of rising from the start temperature to the target starting end temperature. This ensures that the fuel cell can successfully start at the target starting low temperature or at any temperature above the target starting low temperature.

[0073] Optionally, the target startup low temperature of the fuel cell can be set according to actual conditions. For example, the target startup low temperature can be set to -30°C, so that the fuel cell can be successfully started at any temperature of -30°C and above.

[0074] Among them, the impedance of the fuel cell is the sum of the electronic resistance and ionic resistance in the fuel cell. The electronic resistance mainly includes the body resistance of each component in the fuel cell and the contact resistance between the components. The ionic resistance mainly includes the proton conduction resistance of the proton exchange membrane and the catalyst layer in the fuel cell.

[0075] Step S130: Control the fuel cell to start at a low temperature at the target starting voltage.

[0076] Specifically, after the fuel cell is stopped from being purged, when the fuel cell needs to be started at a low temperature, the fuel cell can be controlled to start at a target starting voltage at a low temperature.

[0077] The fuel cell low-temperature startup method provided in an embodiment of the present application determines a target impedance corresponding to the fuel cell's current target fuel cell temperature during the purge period, based on a mapping relationship between the fuel cell temperature and impedance established in the present application. The method then purges the fuel cell until the fuel cell impedance reaches the target impedance, at which point the purge is stopped and the fuel cell is controlled to start at a preset target starting voltage at a low temperature. Furthermore, based on the mapping relationship between the fuel cell impedance corresponding to the fuel cell temperature during the purge period and the residual water content, when the fuel cell impedance reaches the target impedance, the sum of the target residual water content and the target water production generated by the fuel cell when the temperature rises from the target starting low temperature to the target starting end temperature at the target starting voltage does not exceed the allowable water content of the fuel cell. Therefore, when the residual water content of the fuel cell reaches the target residual water content, if the fuel cell is started from the target starting low temperature at the target starting voltage, the water content within the fuel cell does not exceed the allowable water content, and the frozen area within the fuel cell will not completely freeze, thereby not completely preventing the reactant gases from reaching the catalyst surface for electrochemical reactions. If the fuel cell is started at a temperature above the target starting low temperature at the target starting voltage, the water content in the fuel cell will not exceed the allowable water content during the process of rising from the starting temperature to the target starting end temperature. The frozen area inside the fuel cell will not completely freeze, and the fuel cell will start successfully. By precisely setting the end criteria for the low-temperature start pre-purge, the problems of insufficient and excessive purge are avoided, ensuring that the fuel cell can successfully start at or above the target starting low temperature.

[0078] Next, attach Figure 2 The process of determining the mapping relationship between the fuel cell temperature and the impedance during the purge period of the fuel cell is introduced. The process may include:

[0079] S1. Determine the target starting voltage during the low-temperature starting process of the fuel cell.

[0080] Specifically, the starting voltage during the low-temperature start-up of the fuel cell is an important factor affecting the low-temperature start-up of the fuel cell. It is related to the water production during the low-temperature start-up of the fuel cell. Therefore, in order to determine the mapping relationship between the fuel cell temperature and impedance during the purge of the fuel cell, the target starting voltage during the low-temperature start-up of the fuel cell can be determined first.

[0081] Optionally, the target power generation power during the low-temperature start-up of the fuel cell can be determined based on the preset idle power required for the low-temperature start-up of the fuel cell, and the target heating power during the low-temperature start-up of the fuel cell can be determined based on the preset heating power required for the fuel cell to rise from the target starting low temperature to the target starting end temperature, and the target starting voltage corresponding to the target power generation power and the target heating power when the fuel cell meets the target power generation power and the target heating power during the low-temperature start-up process can be determined.

[0082] Specifically, considering that the fuel cell needs to meet idle power requirements during low-temperature startup, and the starting voltage during low-temperature startup is related to the generated power during the low-temperature startup, the target generated power during the low-temperature startup can be determined based on the preset idle power required for the fuel cell to start at low temperatures. Furthermore, the starting voltage during low-temperature startup is also related to the generated power during the low-temperature startup. Therefore, the generated power required to raise the fuel cell temperature from the target starting low temperature to the target startup end temperature can be precalculated. Based on the generated power, the target generated power during the low-temperature startup can be determined. Finally, the target starting voltage can be uniquely determined based on the target generated power and the target generated power.

[0083] S2. Calculate the target heat production required for the fuel cell to be heated from the target startup low temperature to the target startup end temperature.

[0084] S3. Calculating the target water production amount generated when the fuel cell generates the target heat production based on the target starting voltage.

[0085] Specifically, the increase in fuel cell temperature is due to the heat generated by the electrochemical reaction in the fuel cell. The electrochemical reaction in the fuel cell not only generates heat but also produces water. The amount of heat and water generated corresponds to each other. Therefore, the target heat production required for the fuel cell to rise from the target starting low temperature to the target starting end temperature can be calculated. Then, the target water production generated when the fuel cell generates the target heat production can be calculated based on the target starting voltage. That is, the target water production generated when the fuel cell generates the target heat production at the target starting voltage is calculated.

[0086] S4. Determine the allowable water content.

[0087] Specifically, the allowable water content is the amount of water corresponding to when the ice area inside the fuel cell is completely frozen. The failure of the fuel cell to start at low temperature is because the amount of water inside the fuel cell has exceeded the allowable water content before the temperature of the fuel cell rises above the freezing point. Therefore, before the temperature of the fuel cell rises above the freezing point, it is necessary to ensure that the amount of water inside the fuel cell does not exceed the allowable water content. Therefore, the allowable water content of the fuel cell is first determined.

[0088] S5. Subtract the target water production from the allowable water content to obtain the target residual water content.

[0089] Specifically, the target residual water content can be obtained by subtracting the target water production rate from the allowable water content. When the residual water content of the fuel cell is the target residual water content, the water content in the fuel cell does not exceed the allowable water content when the fuel cell is heated from the target starting low temperature to the target starting end temperature at the target starting voltage. The water content in the fuel cell also does not exceed the allowable water content when the fuel cell is heated from a temperature above the target starting low temperature to the target starting end temperature at the target starting voltage.

[0090] S6. Determine each impedance corresponding to the target residual water content according to a preset mapping relationship between the impedance of the fuel cell corresponding to the fuel cell temperature during each purge period and the residual water content.

[0091] Specifically, from the above, it can be seen that if the fuel cell is started at the target starting low temperature or above the target starting low temperature at the target starting voltage, the residual water content of the fuel cell when the fuel cell purge is stopped should be the target residual water content. Considering that the residual water content of a fuel cell cannot be measured during purge in actual applications, but the impedance of the fuel cell can be measured in real time using an impedance meter, the impedance corresponding to the target residual water content can be determined based on the preset mapping relationship between the fuel cell impedance and the residual water content corresponding to the fuel cell temperature during each purge period.

[0092] S7. Establishing a mapping relationship between the fuel cell temperature during each purge period and each impedance corresponding to the target residual water content.

[0093] In an embodiment of the present application, a target water production rate required to generate a fuel cell when the fuel cell is heated from a target starting low temperature to a target starting end temperature at a target starting voltage is calculated, and the target water production rate is subtracted from the allowable water content to obtain a target residual water content. Then, based on a preset mapping relationship between the impedance corresponding to the fuel cell temperature during each purge period and the residual water content, each impedance corresponding to the target residual water content is determined. That is, the impedance of the fuel cell when purging the fuel cell at the fuel cell temperature during different purge periods is determined. This accurately sets the termination criterion for the low-temperature start pre-purge, avoids problems of insufficient purge and excessive purge, and ensures that the fuel cell can be successfully started at temperatures both at the target starting low temperature and above.

[0094] Considering that the allowable water content of a fuel cell is the amount of water corresponding to when its ice region is completely frozen, in order to calculate the allowable water content of the fuel cell, the residual water content of the fuel cell can be first obtained, and then the water production generated by the fuel cell when the fuel cell is started at the target starting low temperature with the residual water content, resulting in the ice region being completely frozen, is calculated. The sum of the residual water content and the water production is then calculated to obtain the allowable water content of the fuel cell. Based on this, the embodiment of the present application introduces the process of determining the allowable water content, which may include:

[0095] A first residual water content of the fuel cell when the fuel cell is purged to a preset time is obtained.

[0096] Specifically, the fuel cell may be purged until a preset time, and then the first residual water content of the fuel cell at this time may be determined.

[0097] Optionally, a first impedance of the fuel cell when the fuel cell is purged to a preset time according to a preset fuel cell temperature during the first purge period can be obtained, and then a first residual water content corresponding to the first impedance can be determined from a mapping relationship between the impedance of the fuel cell corresponding to the fuel cell temperature during the first purge period and the residual water content.

[0098] Optionally, the impedance may be high-frequency impedance, low-frequency impedance, or mass transfer resistance measured by a limiting current density method.

[0099] The first water production amount generated by the fuel cell when the residual water content of the fuel cell is the first residual water content and the fuel cell is started at the target starting low temperature, resulting in the freezing area being completely frozen, is obtained.

[0100] Specifically, when the residual water content of the fuel cell is the first residual water content, a first water production amount generated by the fuel cell when the fuel cell starts to start at the target low starting temperature and the frozen area is completely frozen is calculated.

[0101] The sum of the first residual water content and the first water production is calculated to obtain the allowable water content.

[0102] Specifically, since the allowable water content of the fuel cell is the amount of water corresponding to when its frozen area is completely frozen, the allowable water content of the fuel cell can be obtained by calculating the sum of the first residual water content and the first water production.

[0103] In the embodiment of the present application, the process of obtaining the first water production rate generated by the fuel cell when the residual water content of the fuel cell is the first residual water content and the fuel cell is started at the target startup low temperature, resulting in the complete freezing of the freezing area, is described. The process may include:

[0104] The fuel cell having the first residual water content is started at the target startup low temperature, and a constant-temperature antifreeze fluid is continuously introduced into the fuel cell started at the target startup low temperature. The constant-temperature antifreeze fluid has a temperature equal to the target startup low temperature. Optionally, the constant-temperature antifreeze fluid may have a temperature lower than the target startup low temperature.

[0105] Specifically, a fuel cell having a first residual water content can be allowed to stand in a constant low temperature environment until a predetermined time, typically 12 hours, is reached. This is to ensure that both the internal and external temperatures of the fuel cell are completely at the target startup low temperature. Thereafter, hydrogen and air are introduced into the fuel cell, and the constant low temperature environment, hydrogen, and air temperatures are maintained at the target startup low temperature, so that the fuel cell having the first residual water content can be started at the target startup low temperature. The purpose of continuously introducing constant low temperature antifreeze into the fuel cell that has been started at the target startup low temperature is to ensure that the water inside the fuel cell is completely frozen.

[0106] The fuel cell started at the target starting low temperature is loaded, and the current of the fuel cell is collected in real time until the voltage of the fuel cell drops to a cut-off voltage or the current drops to a cut-off current.

[0107] Specifically, the loading method can adopt the current (or voltage) method. The current loading process refers to the process of controlling the change of the output current of the fuel cell. Usually, the loading current value is generally not more than 0.5A / cm2, and the loading rate is not more than 10A / s. When the voltage of the fuel cell drops to the cut-off voltage or the current drops to the cut-off current, it means that the ice area inside the fuel cell has been completely frozen. Therefore, in the process of loading the fuel cell that starts at the target starting low temperature, the current of the fuel cell is collected in real time until the voltage of the fuel cell drops to the cut-off voltage. Usually, the cut-off voltage can be set to an average of 0.05V per cell, or around 0V.

[0108] Specifically, voltage loading refers to the process of controlling the output voltage of a fuel cell. Typically, the voltage is gradually reduced from an average single-cell open-circuit voltage of approximately 1V, with a typical voltage slope of 0.05V to 0.1V / s. Therefore, during voltage loading of a fuel cell starting at the target low temperature, the fuel cell current is measured in real time until the current drops to the cutoff current. Typically, the cutoff current is set to approximately 5A.

[0109] Determine the function of current change over time based on the current collected in real time (t).

[0110] Specifically, after obtaining the current collected in real time, the function of the current changing with time can be determined based on the current collected in real time. (t), so that according to the function (t) determines a first water production amount generated by the fuel cell when the fuel cell starts to start at the target starting low temperature and causes the ice area to be completely frozen.

[0111] The first water production generated by the fuel cell when the fuel cell starts to start at the target starting low temperature and the freezing area is completely frozen is calculated based on the following formula: :

[0112] .

[0113] Specifically, by calculating the function of current changing with time (t) is time-integrated and multiplied by the molar mass of water, M. H2O , the reciprocal of twice the Faraday constant F and the power generation area of the fuel cell The reciprocal of can be used to calculate the first water production generated when the fuel cell starts to start at the target starting low temperature, resulting in the complete freezing of the freezing area.

[0114] Where F is the Faraday constant, M H2O is the molar mass of water, is the power generation area of the fuel cell.

[0115] In an embodiment of the present application, a fuel cell having a first residual water content is started at a target starting low temperature, and a constant low-temperature antifreeze fluid is continuously introduced into the fuel cell that is started at the target starting low temperature to ensure that the water inside the fuel cell can be completely frozen. The fuel cell that is started at the target starting low temperature is subjected to current (or voltage) loading, and the current of the fuel cell is collected in real time until the voltage (or current) of the fuel cell drops to a cut-off voltage (or cut-off current). A function of the current variation with time from the start of the low-temperature start to the start-up failure of the fuel cell is determined, and the function of the current variation with time is time-integrated to accurately calculate the amount of water produced by the fuel cell when the ice area is completely frozen when the fuel cell is started at the target starting low temperature.

[0116] In the embodiment of the present application, a process for determining a mapping relationship between the impedance of the fuel cell and the residual water content corresponding to the fuel cell temperature during each purge period is described. The process may include:

[0117] A first weight of the fuel cell in a dry state is determined.

[0118] Specifically, considering that the residual water content of a fuel cell cannot be measured directly, it can be determined by weighing. First, the first weight of the fuel cell in a safe and dry state must be determined. The fuel cell can be dried at a high temperature (e.g., 95°C) for a predetermined time to ensure that the fuel cell is in a safe and dry state.

[0119] The fuel cell that has been running to a preset time is purged until the preset time according to the preset fuel cell temperature during each purging period, and the impedance and the second weight of the fuel cell are recorded in real time during the purging of the fuel cell that has been running to the preset time, so as to obtain the impedance and the second weight of the fuel cell at different times at the fuel cell temperature during each purging period.

[0120] Specifically, since the fuel cell contains very little or no water when it is in a safe dry state, the fuel cell in the dry state can be operated until a preset time, or another fuel cell can be used to operate until a preset time, so that an electrochemical reaction occurs inside the fuel cell to produce a certain amount of water so that the fuel cell can be purged. Taking into account that the mapping relationship between the impedance of the fuel cell and the residual water content is different when the fuel cell temperature is different during the purge period, the embodiment of the present application pre-sets multiple fuel cell temperatures during the purge period, and purges the fuel cell that has been operated to the preset time according to the fuel cell temperature during each purge period. During the purge process, the amount of water inside the fuel cell will decrease, and the impedance and weight of the fuel cell will also change, so the impedance and second weight of the fuel cell are recorded in real time until the preset time, and the impedance and second weight of the fuel cell at different times at each fuel cell temperature during the purge period are obtained.

[0121] The first weight is subtracted from the second weight of the fuel cell at different times at the fuel cell temperature during each purge period to obtain the residual water content of the fuel cell at different times at the fuel cell temperature during each purge period.

[0122] Specifically, since the first weight is the weight of the fuel cell in a dry state, the residual water content of the fuel cell at different times at the fuel cell temperature during each purge period can be obtained by subtracting the first weight from the second weight of the fuel cell at different times at the fuel cell temperature during each purge period.

[0123] A mapping relationship between the impedance and residual water content of the fuel cell corresponding to the fuel cell temperature during each purge period is established according to the impedance and residual water content of the fuel cell at different times during the fuel cell temperature during each purge period.

[0124] Specifically, after obtaining the impedance and residual water content of the fuel cell at different times under the fuel cell temperature during each purge period, a mapping relationship between the impedance and residual water content of the fuel cell corresponding to the fuel cell temperature during each purge period can be established. The mapping relationship between the impedance and residual water content of the fuel cell corresponding to the fuel cell temperature during each purge period can be displayed in the form of a fitting curve. Figure 3 As shown, Figure 3 This is a schematic diagram of the mapping relationship between the impedance of the fuel cell and the residual water content corresponding to the fuel cell temperature during each purge period. The mapping relationship between the impedance of the fuel cell and the residual water content corresponding to temperature T1 can be represented by curve f(1), the mapping relationship between the impedance of the fuel cell and the residual water content corresponding to temperature T2 can be represented by curve f(2), and the mapping relationship between the impedance of the fuel cell and the residual water content corresponding to temperature T3 can be represented by curve f(3).

[0125] The embodiment of the present application takes into account that the mapping relationship between the impedance of the fuel cell and the residual water content is different when the fuel cell temperature during the purge period is different. Therefore, multiple fuel cell temperatures during the purge period are pre-set, and a mapping relationship between the impedance of the fuel cell and the residual water content corresponding to the fuel cell temperature during each purge period is established. This can make the target impedance determined based on the mapping relationship between the impedance of the fuel cell and the residual water content more accurate.

[0126] In the embodiment of the present application, the process of calculating the target heat production required for the fuel cell to be heated from the target startup low temperature to the target startup end temperature is introduced. The process may include:

[0127] Calculate the average heat capacity of the fuel cell .

[0128] Calculate the target heat generation required for the fuel cell to rise from the target startup low temperature to the target startup end temperature ,in, is the target start end temperature, activating cryogenic temperatures for said target, is the power generation area of the fuel cell.

[0129] Alternatively, the average heat capacity of the fuel cell can be calculated as follows :

[0130] Determine the mass and mass specific heat capacity of each component that makes up the fuel cell.

[0131] The product of the mass of each component and the mass specific heat capacity is calculated to obtain the average heat capacity of each component.

[0132] Calculate the sum of the average heat capacity of each component to obtain the average heat capacity of the fuel cell .

[0133] Specifically, the average heat capacity of a fuel cell is the sum of the average heat capacities of each component constituting the fuel cell, and the average heat capacity of each component is the product of its mass and its mass specific heat capacity. Therefore, the mass and mass specific heat capacity of each component constituting the fuel cell are first determined. After determining the mass and mass specific heat capacity of each component constituting the fuel cell, the product of the mass and mass specific heat capacity of each component is calculated to obtain the average heat capacity of each component. The sum of the heat capacities of the components is then calculated to obtain the average heat capacity of the fuel cell. .

[0134] See Table 1, which shows the calculation of the average heat capacity of a fuel cell. The components of the fuel cell may mainly include a proton exchange membrane, a catalyst layer, a gas diffusion layer, a frame, a plate and a seal. The mass of the proton exchange membrane is 0.7g, and its specific heat capacity is 1.3J / g / K, so its average heat capacity is 0.91J / K. The mass of the catalyst layer is 0.2g, and its specific heat capacity is 0.2J / g / K, so its average heat capacity is 0.04J / K. The mass of the gas diffusion layer is 2.2g, and its specific heat capacity is 0.6J / g / K, so its average heat capacity is 1.32J / K. The mass of the frame is 5.5g, and its specific heat capacity is 0.5J / g / K, so its average heat capacity is 2.75J / K. The mass of the plate is 110.0g, and its specific heat capacity is 0.5J / g / K, so its average heat capacity is 55J / K. The mass of the seal is 2.5g, and its specific heat capacity is 0.012J / g / K, so its average heat capacity is 0.03J / K. The final calculated average heat capacity of the fuel cell is 60.05J / K.

[0135] Table 1

[0136]

[0137] According to Faraday's law, the relationship between the heat and water generated by the electrochemical reaction in the fuel cell is as follows:

[0138]

[0139] Where Q is the heat generated by the electrochemical reaction in the fuel cell. The theoretical voltage corresponding to the low calorific value, such as 1.25V, is the starting voltage of the fuel cell during low temperature starting, F is the Faraday constant, M H2O is the molar mass of water, I is the function of the current change over time during the electrochemical reaction of the fuel cell, and m is the amount of water produced by the electrochemical reaction of the fuel cell.

[0140] Based on this, in an embodiment of the present application, a process of calculating the target water production generated when the fuel cell generates the target heat production based on the target starting voltage is introduced. This process may include:

[0141] The target water production generated when the fuel cell generates the target heat production is calculated based on the following formula :

[0142] .

[0143] in, is the theoretical voltage corresponding to the low calorific value, is the target starting voltage, F is the Faraday constant, M H2O is the molar mass of water, Produce heat for the target.

[0144] The fuel cell low-temperature starting device provided in an embodiment of the present application is described below. The fuel cell low-temperature starting device described below and the fuel cell low-temperature starting method described above can be referenced to each other.

[0145] First, combine Figure 4 , introduce the fuel cell low temperature starting device, such as Figure 4 As shown, the fuel cell low temperature starting device may include:

[0146] A temperature determination unit 10 is used to determine the target purge period fuel cell temperature of the fuel cell at the current moment;

[0147] a target impedance determination unit 20 for determining a target impedance corresponding to the target fuel cell temperature during the purge period in a preset mapping relationship between the fuel cell temperature and the impedance during the purge period of the fuel cell;

[0148] a purge unit 30 configured to purge the fuel cell until the impedance of the fuel cell reaches the target impedance, and then stop the purge; wherein, according to a mapping relationship between the impedance of the fuel cell and the residual water content corresponding to the fuel cell temperature during the target purge period, when the impedance of the fuel cell reaches the target impedance, the sum of the target residual water content of the fuel cell and the target water production generated by the fuel cell when the temperature rises from a preset target starting low temperature to a preset target starting end temperature at a preset target starting voltage does not exceed an allowable water content of the fuel cell, where the allowable water content is the amount of water corresponding to when the frozen area inside the fuel cell is completely frozen;

[0149] The control starting unit 40 is used to control the fuel cell to start at a low temperature under the target starting voltage.

[0150] Optionally, the fuel cell low-temperature starting device may further include:

[0151] a target starting voltage determining unit, configured to determine the target starting voltage during the low-temperature starting process of the fuel cell;

[0152] A target heat production calculation unit, configured to calculate a target heat production required for the fuel cell to be heated from the target startup low temperature to the target startup end temperature;

[0153] a target water production calculation unit, configured to calculate the target water production generated when the fuel cell generates the target heat production based on the target starting voltage;

[0154] an allowable moisture content measuring unit, used for measuring the allowable moisture content;

[0155] a target residual water content calculation unit, configured to obtain the target residual water content by subtracting the target water production from the allowable water content;

[0156] an impedance determination unit, configured to determine each impedance corresponding to the target residual water content according to a mapping relationship between the impedance of the fuel cell corresponding to the fuel cell temperature during each preset purge period and the residual water content;

[0157] The first mapping relationship establishing unit is configured to establish a mapping relationship between the fuel cell temperature during each purge period and each impedance corresponding to the target residual water content.

[0158] Optionally, the process of the target starting voltage determining unit determining the target starting voltage during the low-temperature starting process of the fuel cell may include:

[0159] Determining the target power generation during the low-temperature startup of the fuel cell according to the preset idle power required for the low-temperature startup of the fuel cell;

[0160] Determining the target heating power during the low-temperature startup of the fuel cell according to the preset heating power required for the fuel cell to heat up from the target startup low temperature to the target startup end temperature;

[0161] A target starting voltage corresponding to when the fuel cell meets the target power generation power and the target heat generation power during low-temperature starting is determined.

[0162] Optionally, the allowable moisture content measuring unit may include:

[0163] a first residual water content obtaining unit, configured to obtain a first residual water content of the fuel cell when the fuel cell is purged to a preset time;

[0164] a first water production acquisition unit, configured to acquire a first water production generated by the fuel cell when the residual water content of the fuel cell is the first residual water content and the fuel cell is started at the target starting low temperature, resulting in the freezing area being completely frozen;

[0165] The allowable water content calculation unit is used to calculate the sum of the first residual water content and the first water production to obtain the allowable water content.

[0166] Optionally, the process of the first residual water content obtaining unit obtaining the first residual water content of the fuel cell when the fuel cell is purged to a preset time may include:

[0167] obtaining a first impedance of the fuel cell when the fuel cell is purged to a preset time according to a preset fuel cell temperature during a first purge period;

[0168] In the mapping relationship between the impedance of the fuel cell corresponding to the fuel cell temperature during the first purge period and the residual water content, a first residual water content corresponding to the first impedance is determined.

[0169] Optionally, the process in which the first water production acquisition unit acquires the first water production generated by the fuel cell when the residual water content of the fuel cell is the first residual water content and the startup is started at the target startup low temperature, resulting in the freezing area being completely frozen, may include:

[0170] Starting the fuel cell having the first residual water content at the target starting low temperature, and continuously introducing a constant-low-temperature antifreeze solution into the fuel cell starting at the target starting low temperature, wherein the temperature of the constant-low-temperature antifreeze solution is the target starting low temperature;

[0171] Loading the fuel cell that starts to start at the target starting low temperature, and collecting the current of the fuel cell in real time until the voltage of the fuel cell drops to a cut-off voltage or the current drops to a cut-off current;

[0172] Determine the function of current change over time based on the current collected in real time (t);

[0173] The first water production generated by the fuel cell when the fuel cell starts to start at the target starting low temperature and the freezing area is completely frozen is calculated based on the following formula: :

[0174] ;

[0175] Where F is the Faraday constant, M H2O is the molar mass of water, is the power generation area of the fuel cell.

[0176] Optionally, the fuel cell low-temperature starting device may further include:

[0177] a first weight determining unit, configured to determine a first weight of the fuel cell in a dry state;

[0178] an impedance and second weight determining unit, configured to purge the fuel cell that has been operated to a preset time until a preset time according to a preset fuel cell temperature during each purge period, and to record the impedance and second weight of the fuel cell in real time during the purge of the fuel cell that has been operated to the preset time, thereby obtaining the impedance and second weight of the fuel cell at different times at the fuel cell temperature during each purge period;

[0179] a residual water content obtaining unit at different times, configured to obtain the residual water content of the fuel cell at different times during the fuel cell temperature during each purge period by subtracting the first weight from the second weight of the fuel cell at different times during the fuel cell temperature;

[0180] The second mapping relationship establishing unit is used to establish a mapping relationship between the impedance and residual water content of the fuel cell corresponding to the fuel cell temperature during each purge period according to the impedance and residual water content of the fuel cell at different times during the fuel cell temperature during each purge period.

[0181] Optionally, the target heat production calculation unit may include:

[0182] Average heat capacity calculation unit, used to calculate the average heat capacity of the fuel cell ;

[0183] The first target heat generation calculation unit is used to calculate the target heat generation required for the fuel cell to rise from the target startup low temperature to the target startup end temperature. ,in, is the target start end temperature, activating cryogenic temperatures for said target, is the power generation area of the fuel cell.

[0184] Optionally, the average heat capacity calculation unit calculates the average heat capacity of the fuel cell The process may include:

[0185] Determining the mass and mass specific heat capacity of each component constituting the fuel cell;

[0186] Calculating the product of the mass of each component and the mass specific heat capacity to obtain the average heat capacity of each component;

[0187] Calculate the sum of the average heat capacity of each component to obtain the average heat capacity of the fuel cell .

[0188] Optionally, the process of the target water production calculation unit calculating the target water production generated when the fuel cell generates the target heat production based on the target starting voltage may include:

[0189] The target water production generated when the fuel cell generates the target heat production is calculated based on the following formula

[0190] ;

[0191] in, is the theoretical voltage corresponding to the low calorific value, is the target starting voltage, F is the Faraday constant, M H2O is the molar mass of water, Produce heat for the target.

[0192] The fuel cell low-temperature starting device provided in the embodiment of the present application can be applied to fuel cell low-temperature starting equipment. Figure 5 The hardware structure diagram of the fuel cell low temperature starting device is shown. Figure 5 , the hardware structure of the fuel cell low temperature starting device may include: at least one processor 1, at least one communication interface 2, at least one memory 3 and at least one communication bus 4;

[0193] In the embodiment of the present application, the number of the processor 1, the communication interface 2, the memory 3, and the communication bus 4 is at least one, and the processor 1, the communication interface 2, and the memory 3 communicate with each other through the communication bus 4;

[0194] The processor 1 may be a central processing unit (CPU), or an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present invention;

[0195] The memory 3 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory;

[0196] The memory stores a program, and the processor can call the program stored in the memory, wherein the program is used to implement each processing flow in the aforementioned fuel cell low-temperature startup solution.

[0197] An embodiment of the present application further provides a storage medium, which can store a program suitable for execution by a processor, wherein the program is used to implement each processing flow in the aforementioned fuel cell low-temperature startup scheme.

[0198] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0199] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0200] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fuel cell low temperature startup method, characterized in that: include: determining a target fuel cell temperature during a purge period of the fuel cell at a current moment; Determining a target impedance corresponding to the target fuel cell temperature during the purge period in a preset mapping relationship between the fuel cell temperature and the impedance during the purge period of the fuel cell; The fuel cell is purged until the impedance of the fuel cell reaches the target impedance, and the purging is stopped, wherein, according to a mapping relationship between the impedance of the fuel cell and the residual water content corresponding to the fuel cell temperature during the target purge period, when the impedance of the fuel cell reaches the target impedance, the sum of the target residual water content of the fuel cell and the target water production generated by the fuel cell when the temperature rises from a preset target starting low temperature to a preset target starting end temperature at a preset target starting voltage does not exceed an allowable water content of the fuel cell, where the allowable water content is the amount of water corresponding to when the frozen area inside the fuel cell is completely frozen; Controlling the fuel cell to start at a low temperature at the target starting voltage; The process of determining the mapping relationship between the fuel cell temperature and the impedance during the fuel cell purge period includes: Determining the target starting voltage during the low-temperature starting process of the fuel cell; Calculating a target heat output required for the fuel cell to be heated from the target startup low temperature to the target startup end temperature; calculating, based on the target starting voltage, the target water production amount generated when the fuel cell generates the target heat production; Determining the allowable moisture content; Subtracting the target water production from the allowable water content to obtain the target residual water content; determining each impedance corresponding to the target residual water content according to a mapping relationship between the impedance of the fuel cell corresponding to the fuel cell temperature during each preset purge period and the residual water content; A mapping relationship between the fuel cell temperature during each purge period and each impedance corresponding to the target residual water content is established.

2. The method according to claim 1, characterized in that Determining the target starting voltage during the low-temperature starting process of the fuel cell includes: Determining the target power generation during the low-temperature startup of the fuel cell according to the preset idle power required for the low-temperature startup of the fuel cell; Determining the target heating power during the low-temperature startup of the fuel cell according to the preset heating power required for the fuel cell to heat up from the target startup low temperature to the target startup end temperature; A target starting voltage corresponding to when the fuel cell meets the target power generation power and the target heat generation power during low-temperature starting is determined.

3. The method according to claim 1, characterized in that Determining the allowable moisture content comprises: obtaining a first residual water content of the fuel cell when the fuel cell is purged to a preset time; obtaining a first water production amount generated by the fuel cell when the residual water content of the fuel cell is the first residual water content and the fuel cell is started at the target starting low temperature, resulting in the freezing area being completely frozen; The sum of the first residual water content and the first water production is calculated to obtain the allowable water content.

4. The method according to claim 3, characterized in that The obtaining of a first residual water content of the fuel cell when the fuel cell is purged to a preset time includes: obtaining a first impedance of the fuel cell when the fuel cell is purged to a preset time according to a preset fuel cell temperature during a first purge period; In a mapping relationship between the impedance of the fuel cell corresponding to the fuel cell temperature during the first purge period and the residual water content, a first residual water content corresponding to the first impedance is determined.

5. The method according to claim 3, characterized in that Obtaining a first water production amount generated by the fuel cell when the residual water content of the fuel cell is the first residual water content and the fuel cell is started at the target starting low temperature, resulting in the freezing area being completely frozen, includes: Starting the fuel cell having the first residual water content at the target starting low temperature, and continuously introducing a constant-low-temperature antifreeze solution into the fuel cell starting at the target starting low temperature, wherein the temperature of the constant-low-temperature antifreeze solution is the target starting low temperature; Loading the fuel cell that starts to start at the target starting low temperature, and collecting the current of the fuel cell in real time until the voltage of the fuel cell drops to a cut-off voltage or the current drops to a cut-off current; Determine the function of current change over time based on the current collected in real time (t); The first water production generated by the fuel cell when the fuel cell starts to start at the target starting low temperature and the freezing area is completely frozen is calculated based on the following formula: : ； Where F is the Faraday constant, M H2O is the molar mass of water, is the power generation area of the fuel cell.

6. The method according to claim 1, characterized in that The process of determining the mapping relationship between the impedance of the fuel cell and the residual water content corresponding to the fuel cell temperature during each purge period includes: determining a first weight of the fuel cell in a dry state; Purging the fuel cell that has been running until a preset time according to a preset fuel cell temperature during each purge period until a preset time, and recording the impedance and the second weight of the fuel cell in real time during the purge of the fuel cell that has been running until the preset time, to obtain the impedance and the second weight of the fuel cell at different times at the fuel cell temperature during each purge period; Subtracting the first weight from the second weight of the fuel cell at different times under the fuel cell temperature during each purge period to obtain the residual water content of the fuel cell at different times under the fuel cell temperature during each purge period; A mapping relationship between the impedance and residual water content of the fuel cell corresponding to the fuel cell temperature during each purge period is established according to the impedance and residual water content of the fuel cell at different times during the fuel cell temperature during each purge period.

7. The method according to claim 1, characterized in that Calculating a target heat production required for the fuel cell to be heated from the target startup low temperature to the target startup end temperature includes: Calculate the average heat capacity of the fuel cell ; Calculate the target heat generation required for the fuel cell to rise from the target startup low temperature to the target startup end temperature ,in, is the target start end temperature, activating cryogenic temperatures for said target, is the power generation area of the fuel cell.

8. The method according to claim 7, characterized in that Calculate the average heat capacity of the fuel cell ,include: Determining the mass and mass specific heat capacity of each component constituting the fuel cell; Calculating the product of the mass of each component and the mass specific heat capacity to obtain the average heat capacity of each component; Calculate the sum of the average heat capacity of each component to obtain the average heat capacity of the fuel cell .

9. The method according to any one of claims 1 to 8, characterized in that Calculating the target water production amount generated when the fuel cell generates the target heat production based on the target starting voltage includes: The target water production generated when the fuel cell generates the target heat production is calculated based on the following formula : ； in, is the theoretical voltage corresponding to the low calorific value, is the target starting voltage, F is the Faraday constant, M H2O is the molar mass of water, Produce heat for the target.

10. A fuel cell low temperature starting device, characterized in that: include: a temperature determination unit, configured to determine a target fuel cell purge period fuel cell temperature at a current moment; a target impedance determining unit, configured to determine a target impedance corresponding to the target fuel cell temperature during the purge period in a preset mapping relationship between the fuel cell temperature and the impedance during the purge period of the fuel cell; a purge unit configured to purge the fuel cell until the impedance of the fuel cell reaches the target impedance, and then stop the purge; wherein, according to a mapping relationship between the impedance of the fuel cell and the residual water content corresponding to the fuel cell temperature during the target purge period, when the impedance of the fuel cell reaches the target impedance, the sum of the target residual water content of the fuel cell and the target water production generated by the fuel cell when the temperature rises from a preset target starting low temperature to a preset target starting end temperature at a preset target starting voltage does not exceed an allowable water content of the fuel cell, where the allowable water content is the amount of water corresponding to when the frozen area inside the fuel cell is completely frozen; and wherein a process for determining the mapping relationship between the fuel cell temperature and the impedance during the purge period includes: Determining the target starting voltage during the low-temperature starting process of the fuel cell; Calculating a target heat output required for the fuel cell to be heated from the target startup low temperature to the target startup end temperature; calculating, based on the target starting voltage, the target water production amount generated when the fuel cell generates the target heat production; Determining the allowable moisture content; Subtracting the target water production from the allowable water content to obtain the target residual water content; determining each impedance corresponding to the target residual water content according to a mapping relationship between the impedance of the fuel cell corresponding to the fuel cell temperature during each preset purge period and the residual water content; Establishing a mapping relationship between the fuel cell temperature during each purge period and each impedance corresponding to the target residual water content; A control starting unit is used to control the fuel cell to start at a low temperature under the target starting voltage.

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