Fuel cell system low-temperature startup method, device, equipment and storage medium

Abstract

The present application discloses a low-temperature startup method, device, equipment and storage medium for a fuel cell system. The method continuously increases the current of the fuel cell stack until it is determined that the instantaneous heat generation of the fuel cell stack at the current current and current temperature is not less than the minimum instantaneous heat generation currently required, and continuously introduces air into the fuel cell stack based on the minimum air path energy at the determined current and temperature, thereby ensuring that the reaction water in the fuel cell stack does not freeze inside the fuel cell stack and is promptly carried out by the air. Thereafter, as the temperature of the fuel cell stack rises, the instantaneous heat generation of the fuel cell stack is ensured to be always no less than the minimum instantaneous heat generation that should be generated, and the corresponding minimum air path energy is provided so that the reaction water does not freeze inside the fuel cell stack and is completely carried away by the air, thereby ensuring the successful startup of the fuel cell system.

Description

Technical Field

[0001] The present application relates to the field of fuel cell technology, and more specifically, to a low-temperature startup method, device, equipment, and storage medium for a fuel cell system. Background Art

[0002] Proton exchange membrane fuel cells are power generation devices that generate electricity, heat and water through electrochemical reactions between hydrogen and oxygen in the air. Fuel cells are widely used in the automotive industry due to their high conversion efficiency, no harmful substances produced during the electrochemical reaction process, and low noise.

[0003] When using fuel cells, multiple fuel cells are typically connected in series to form a stack, which is then integrated with a corresponding auxiliary system to form a fuel cell system. When the stack temperature in the fuel cell system drops below zero degrees Celsius during startup, the water produced by the stack will freeze inside the stack. Once frozen, it will prevent the reactant gases from reaching the catalyst surface. If the stack cannot promptly discharge the liquid water and heat up to melt the ice before the ice completely blocks the stack, the low-temperature startup will fail. With the commercial application of fuel cell systems, low-temperature startup of fuel cell systems has become an important indicator for measuring fuel cell system performance. How to successfully achieve low-temperature startup of fuel cell systems remains a major challenge. Summary of the Invention

[0004] In view of this, the present application provides a fuel cell system low-temperature start-up method, device, equipment and storage medium, which are used to solve the problem that the existing fuel cell system low-temperature start-up method cannot guarantee the successful low-temperature start-up of the fuel cell system.

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

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

[0007] Setting the current of the fuel cell stack in the fuel cell system;

[0008] Determining the current temperature of the fuel cell stack;

[0009] Determining a target minimum air path energy corresponding to the current of the fuel cell stack and the current temperature of the fuel cell stack in a first mapping relationship among a preset current, a temperature, and a minimum air path energy;

[0010] continuously passing hydrogen into the anode of the stack and continuously passing air into the cathode of the stack based on the target minimum air path energy, where the target minimum air path energy is the kinetic energy of the air required to carry away all water produced by the reaction of the air and the hydrogen in the stack;

[0011] Determining a target minimum instantaneous heat production corresponding to the current of the fuel cell stack and the current temperature of the fuel cell stack in a preset second mapping relationship among current, temperature, and minimum instantaneous heat production, wherein the target minimum instantaneous heat production is the minimum instantaneous heat that the fuel cell stack should generate to ensure that the water does not freeze before all the water is carried away by the air;

[0012] Determining whether the current instantaneous heat generation of the fuel cell stack is less than the target minimum instantaneous heat generation;

[0013] If so, increase the current of the fuel cell stack according to the set step size until the current instantaneous heat production of the fuel cell stack calculated according to the increased current of the fuel cell stack is not less than the target minimum instantaneous heat production, and determine whether the fuel cell stack meets the preset low-temperature startup end condition;

[0014] If the fuel cell stack does not meet the low-temperature startup termination condition, returning to the step of determining the current temperature of the fuel cell stack;

[0015] If the fuel cell stack meets the low-temperature startup end condition, it indicates that the low-temperature startup of the fuel cell system is successful.

[0016] Preferably, before determining whether the fuel cell stack meets a preset low-temperature startup termination condition, the method further includes:

[0017] Determining the power demand of the fuel cell system for the entire vehicle;

[0018] If the output power of the fuel cell system at the current moment is equal to the required power, determining whether the fuel cell stack meets the preset low-temperature startup end condition;

[0019] If the output power of the fuel cell system at the current moment is less than the required power, the current of the fuel cell stack is increased according to a set step size until the output power of the fuel cell system at the current moment obtained according to the increased current of the fuel cell stack is equal to the required power, and it is determined whether the fuel cell stack meets the preset low-temperature startup end condition;

[0020] If the output power of the fuel cell system at the current moment is greater than the required power, the target minimum air path energy at the current moment is increased according to a set step size, and air is continuously introduced into the fuel cell stack based on the increased target minimum air path energy until the output power of the fuel cell system at the current moment obtained according to the increased target minimum air path energy is equal to the required power, and it is determined whether the fuel cell stack meets the preset low-temperature startup end condition;

[0021] Preferably, the process of determining the second mapping relationship among the current, temperature and minimum instantaneous heat generation includes:

[0022] Based on the preset currents and temperatures, the minimum instantaneous heat generation corresponding to each current and temperature is calculated as Q=n*(1.25-U)*I, where n is the number of cells in the stack, U is the maximum average cell voltage allowed by the stack at each current and temperature, and I is the current;

[0023] A second mapping relationship among each current, each temperature and each minimum instantaneous heat generation is established.

[0024] Preferably, the calculation process of the current instantaneous heat generation of the fuel cell stack includes:

[0025] Calculate the current instantaneous heat generation of the fuel cell stack as Q=n*(1.25-U)*I, where n is the number of cells in the fuel cell stack, U is the current average cell voltage of the fuel cell stack, and I is the current current of the fuel cell stack.

[0026] Preferably, the process of determining the output power of the fuel cell system at the current moment includes:

[0027] Determining a first power of the fuel cell stack at a current moment;

[0028] Determining a second power consumed by other electrical components in the fuel cell system except the fuel cell stack at a current moment;

[0029] The output power of the fuel cell system at the current moment is obtained by subtracting the second power from the first power.

[0030] Preferably, the process of determining whether the fuel cell stack meets a preset low-temperature startup termination condition includes:

[0031] Determining whether the current temperature of the fuel cell stack is greater than a preset startup end temperature and whether the cumulative value of the instantaneous heat generation of the fuel cell stack is greater than the heat required for the system coolant and the fuel cell stack in the fuel cell system to rise from the temperature at the start of startup to above the startup end temperature;

[0032] If the current temperature of the fuel cell stack is greater than the start-up end temperature and the cumulative value of the instantaneous heat generation of the fuel cell stack is greater than the heat required for the system coolant in the fuel cell system and the fuel cell stack to rise from the temperature at the start of startup to above the start-up end temperature, it is determined that the fuel cell stack meets the preset low-temperature start-up end conditions.

[0033] A low temperature starting device for a fuel cell system, current;

[0034] a temperature determination unit, configured to determine the current temperature of the fuel cell stack;

[0035] a target minimum air path energy determination unit, configured to determine the target minimum air path energy corresponding to the current of the stack and the current temperature of the stack in a first mapping relationship among the preset current, temperature and minimum air path energy;

[0036] a gas introduction unit, configured to continuously introduce hydrogen into the anode of the stack and continuously introduce air into the cathode of the stack based on the target minimum air path energy, wherein the target minimum air path energy is the kinetic energy of the air required to carry away all water produced by the reaction of the air and the hydrogen in the stack;

[0037] a target minimum instantaneous heat production determination unit, configured to determine, from a preset second mapping relationship among current, temperature, and minimum instantaneous heat production, a target minimum instantaneous heat production corresponding to the current of the stack and the current temperature of the stack, wherein the target minimum instantaneous heat production is the minimum instantaneous heat that the stack should generate to ensure that the water does not freeze before all the water is carried away by the air;

[0038] a heat generation determination unit, configured to determine whether the current instantaneous heat generation of the stack is less than the target minimum instantaneous heat generation;

[0039] If yes, then execute the following steps of the current adjustment unit; if no, then execute the following steps of the low temperature start end judgment unit;

[0040] a current adjustment unit, configured to increase the current of the fuel cell stack according to a set step size and return to execute the steps of the temperature determination unit;

[0041] A low-temperature startup end judgment unit, used to judge whether the fuel cell stack meets a preset low-temperature startup end condition;

[0042] If the fuel cell stack does not meet the low-temperature startup end condition, returning to the step of executing the temperature determination unit;

[0043] If the stack meets the low-temperature startup end condition, the following steps are performed to indicate a successful startup unit:

[0044] The startup success characterization unit is used to characterize the success of the low-temperature startup of the fuel cell system.

[0045] Preferably, it also includes:

[0046] A power demand determination unit, configured to determine the power demand of the fuel cell system by the entire vehicle;

[0047] a first power adjustment unit, configured to execute the steps of the low-temperature startup end judgment unit if the output power of the fuel cell system at a current moment is equal to the required power;

[0048] a second power adjustment unit configured to, if the output power of the fuel cell system at a current moment is less than the required power, increase the current of the fuel cell stack according to a set step size until the output power of the fuel cell system at the current moment obtained according to the increased current of the fuel cell stack is equal to the required power, and execute the steps of the low-temperature start end judgment unit;

[0049] The third power adjustment unit is used to increase the target minimum air path energy at the current moment according to the set step size if the output power of the fuel cell system at the current moment is greater than the required power, and continuously introduce air into the fuel cell stack based on the increased target minimum air path energy until the output power of the fuel cell system at the current moment obtained according to the increased target minimum air path energy is equal to the required power, and then execute the steps of the low-temperature start-up end judgment unit.

[0050] A fuel cell system low-temperature starting device, comprising a memory and a processor;

[0051] The memory is used to store programs;

[0052] The processor is used to execute the program to implement the various steps of the aforementioned low-temperature startup method for the fuel cell system.

[0053] A storage medium stores a computer program, which, when executed by a processor, implements the various steps of the aforementioned low-temperature startup method for a fuel cell system.

[0054] It can be seen from the above technical solution that the low-temperature start-up method for fuel cells provided in the embodiment of the present application pre-establishes a first mapping relationship among current, temperature and minimum air path energy and a second mapping relationship among current, temperature and minimum instantaneous heat production. First, the current of the fuel cell stack in the fuel cell system is set, and the current of the fuel cell stack is continuously increased until it is determined that the instantaneous heat production of the fuel cell stack at the current current and current temperature is not less than the minimum instantaneous heat production that the fuel cell stack should generate at the current current and current temperature as determined in the second mapping relationship, and the final current of the fuel cell stack is obtained. In this process, the target minimum air path energy is also determined in the first mapping relationship at all times according to the fuel cell stack current and the corresponding temperature, and air is continuously introduced into the fuel cell stack based on the determined target minimum air path energy. According to the first mapping relationship, it can be seen that the target minimum air path energy is the water generated by the reaction of the air introduced into the fuel cell stack at its corresponding current and temperature. The kinetic energy of the air when all of it is carried away by the air. According to the second mapping relationship, the minimum instantaneous heat production is the minimum instantaneous heat that the stack should generate to ensure that the water does not freeze before all of the water is carried away by the air. Therefore, when the current of the stack is the final current and the temperature is the temperature corresponding to the final current, air will continue to be introduced into the stack based on the target minimum air path energy determined at this time, and the instantaneous heat production at this time is not less than the minimum instantaneous heat production that the stack should generate at this time. This can ensure that the water generated by the stack reaction at this time does not freeze in the stack and can be carried out by the air in time. When the stack does not meet the preset low-temperature start-up termination conditions, the final current will be adjusted to ensure that the instantaneous heat production of the stack will not be less than the minimum instantaneous heat production that the stack should generate, and provide the corresponding minimum air path energy to prevent the reaction water from freezing inside the stack and being carried away by the air, thereby ensuring the successful start-up of the fuel cell system.

[0055] Furthermore, since the target minimum air path energy required by the fuel cell stack is determined according to the current and temperature of the fuel cell stack, and air is introduced into the fuel cell stack based on the determined target minimum air path energy, there is no need to supply excessive air path energy, which can effectively save the power consumption of the air path accessories of the fuel cell system and improve the energy utilization rate during the startup of the fuel cell system. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] 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.

[0057] Figure 1 A schematic diagram of an optional fuel cell system structure disclosed in an embodiment of the present application;

[0058] Figure 2 This is a flow chart of a low-temperature startup method for a fuel cell system disclosed in an embodiment of the present application;

[0059] Figure 3 This is a flow chart of another low-temperature startup method for a fuel cell system disclosed in an embodiment of the present application;

[0060] Figure 4 This is a flow chart of another low-temperature startup method for a fuel cell system disclosed in an embodiment of the present application;

[0061] Figure 5 This is a schematic structural diagram of a low-temperature starting device for a fuel cell system disclosed in an embodiment of the present application;

[0062] Figure 6 This is a hardware structure block diagram of a low-temperature starting device for a fuel cell system disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0063] 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.

[0064] The present application provides a low-temperature start-up solution for a fuel cell system, which can be applied to a fuel cell system composed of a stack composed of multiple proton exchange membrane fuel cells and a set of corresponding auxiliary systems. First, an optional fuel cell system applicable to the present application is introduced, such as Figure 1 As shown, Figure 1 A structural schematic diagram of an optional fuel cell system provided in an embodiment of the present application, a fuel cell system provided in an embodiment of the present application may include: an air subsystem, a cooling subsystem, a hydrogen subsystem and a fuel cell stack, the air subsystem mainly consisting of an air compressor, a back pressure valve and an intermediate connecting pipe, the air subsystem can provide sufficient air for the fuel cell stack to participate in the chemical reaction; the cooling subsystem mainly consists of an intercooler, a radiator, a thermostat, a cooling pump, a water tank, an inlet temperature sensor T1, an outlet temperature sensor T2 and an intermediate connecting pipe, the function of the cooling subsystem is to cool the heat generated by the chemical reaction inside the fuel cell stack, so that the fuel cell stack is at the optimal temperature to ensure efficient operation; the hydrogen subsystem mainly consists of a hydrogen inlet solenoid valve, a hydrogen circulation pump, an anode water separator, a hydrogen exhaust solenoid valve and an intermediate connecting pipe, the hydrogen subsystem inputs hydrogen into the fuel cell stack through the hydrogen inlet solenoid valve, so that the hydrogen in the fuel cell stack fully reacts chemically with the oxygen in the air, while discharging liquid water on the hydrogen side, and supplying it to the fuel cell stack again after pressurization by the hydrogen circulation pump.

[0065] Next, attach Figure 2 The low temperature start-up method of the fuel cell system of the present application is described as follows: Figure 2 As shown, the method may include:

[0066] Step S100: setting the current of the fuel cell stack in the fuel cell system.

[0067] Step S110: Determine the current temperature of the fuel cell stack.

[0068] Specifically, a fuel cell stack is a battery stack in a fuel cell system composed of multiple single fuel cells stacked in series. The current of the fuel cell stack in the fuel cell system set at the initial moment is usually a preset smaller value, such as 5A. The specific smaller value can be determined according to the performance of the fuel cell stack and the temperature of the fuel cell stack at the current moment is determined.

[0069] Step S120 : determining a target minimum air path energy corresponding to the current of the fuel cell stack and the current temperature of the fuel cell stack in a first mapping relationship among the preset current, temperature, and minimum air path energy.

[0070] Specifically, air path energy refers to the kinetic energy possessed by air, which is used to carry water generated by the stack out of the stack. The minimum air path energy refers to the minimum kinetic energy of air that the fuel cell system should provide to the stack. If the kinetic energy of the air actually provided to the stack is less than the minimum kinetic energy, the water generated by the air reaction in the stack cannot be carried out of the stack, resulting in accumulation inside the stack. If the temperature of the stack is at or below freezing at this time, the accumulated water inside the stack will freeze, blocking the air flow path of the stack. Considering that the minimum air path energy is related to the current and temperature of the stack, different stack currents and temperatures will correspond to different minimum air path energies. Therefore, a first mapping relationship between current, temperature, and minimum air path energy is pre-established so that the minimum air path energy required by the stack at different times can be determined based on the current and temperature of the stack at different times. As can be seen from the above, the current of the fuel cell stack is set and the current temperature of the stack is determined. Therefore, the target minimum air path energy corresponding to the stack current and the current temperature of the stack should be determined in the first mapping relationship.

[0071] Step S130, continuously introduce hydrogen into the anode of the fuel cell stack and continuously introduce air into the cathode of the fuel cell stack based on the target minimum air path energy, wherein the target minimum air path energy is the kinetic energy of the air required when all water produced by the reaction of the air and the hydrogen in the fuel cell stack is carried away by the air.

[0072] Specifically, the target minimum air path energy required by the stack at the current current and temperature has been determined. Therefore, hydrogen can be introduced into the anode of the stack, and air can be continuously introduced into the cathode of the stack based on the target minimum air path energy, so that the air and hydrogen undergo an electrochemical reaction to enable the stack to start at a low temperature. The kinetic energy of the air introduced at this time is the target minimum air path energy, which is the minimum kinetic energy of the air required to carry away all water produced by the reaction of air and hydrogen in the stack. The air compressor in the fuel cell system can be controlled to compress the air so that the air introduced into the stack has the determined target minimum air path energy.

[0073] Step S140: Determine the target minimum instantaneous heat production corresponding to the current of the battery stack and the temperature of the battery stack at the current moment in a second mapping relationship among the preset current, temperature and minimum instantaneous heat production. The target minimum instantaneous heat production is the minimum instantaneous heat that the battery stack should generate to ensure that the water does not freeze before all the water is carried away by the air.

[0074] Specifically, considering that the low-temperature start-up of the fuel cell system is started when the temperature is at or below freezing, and when the temperature of the stack is at or below freezing, the water generated by the reaction of air and hydrogen inside the stack may freeze before being carried away by the air, resulting in the air being unable to carry away the ice formed by the water. Therefore, it is necessary to ensure that the water does not freeze before all the water is carried away by the air, so that the air can carry away the water in time. Since the air and hydrogen react to generate water while also generating heat, if it is to be ensured that the water does not freeze before all the water is carried away by the air, it is necessary to meet the requirements of the air and hydrogen reaction to generate water. The instantaneous heat production reaches the minimum instantaneous heat production. When the instantaneous heat production generated by the reaction of air and hydrogen reaches the minimum instantaneous heat production, it can be ensured that all water can be taken away by the air before freezing. The size of the minimum instantaneous heat production is related to the current and temperature of the fuel cell stack. The current and temperature of the fuel cell stack are different, and the minimum instantaneous heat production required is also different. Therefore, the embodiment of the present application pre-establishes a second mapping relationship between current, temperature and minimum instantaneous heat production, so that the minimum instantaneous heat production required by the fuel cell stack at different times can be determined based on the current and temperature of the fuel cell stack at different times. As can be seen from the above, the current of the fuel cell stack is set, and the temperature of the fuel cell stack at the current moment is determined. Therefore, the target minimum instantaneous heat production corresponding to the current of the fuel cell stack and the temperature of the fuel cell stack at the current moment should be determined in the second mapping relationship.

[0075] Step S150: Determine whether the current instantaneous heat generation of the fuel cell stack is less than the target minimum instantaneous heat generation.

[0076] Specifically, after determining the target minimum instantaneous heat production in the second mapping relationship among current, temperature and minimum instantaneous heat production, it is necessary to determine whether the current instantaneous heat production of the battery stack is less than the target minimum instantaneous heat production, so as to adjust the current of the battery stack according to the judgment result.

[0077] If so, execute the following step S160.

[0078] Step S160: Increase the current of the fuel cell stack according to the set step size until the current instantaneous heat production of the fuel cell stack calculated according to the increased current of the fuel cell stack is not less than the target minimum instantaneous heat production, and determine whether the fuel cell stack meets the preset low-temperature startup end condition.

[0079] Specifically, if the current instantaneous heat production of the fuel cell stack is less than the target minimum instantaneous heat production required by the current fuel cell stack, it means that the current of the fuel cell stack is small at this time, resulting in insufficient instantaneous heat production of the fuel cell stack. Therefore, the current of the fuel cell stack is increased according to the set step value until the current instantaneous heat production of the fuel cell stack calculated according to the increased current of the fuel cell stack is not less than the target minimum instantaneous heat production. At this time, a final fuel cell stack current is obtained, and when the temperature is the temperature corresponding to the final current, air will continue to be introduced into the fuel cell stack based on the target minimum air path energy determined at this time, and the instantaneous heat production at this time is not less than the minimum instantaneous heat production that the fuel cell stack should generate at this time. This can ensure that the water generated by the fuel cell stack reaction at this time does not freeze in the fuel cell stack and can be carried out by the air in time. At this time, it should be determined whether the fuel cell stack meets the preset low-temperature start-up end conditions.

[0080] If the fuel cell stack does not meet the low-temperature startup termination condition, the process returns to step S110 .

[0081] Specifically, if the fuel cell stack does not meet the low-temperature startup termination conditions, since it is determined that the instantaneous heat production of the fuel cell stack is not less than the minimum instantaneous heat production that the fuel cell stack should generate, air will continue to be introduced into the fuel cell stack based on the target minimum air path energy corresponding to the final current, so the temperature of the fuel cell stack will increase. At this time, the above-mentioned steps of determining the temperature of the fuel cell stack at the current moment should be returned to ensure that the instantaneous heat production of the fuel cell stack will always be no less than the minimum instantaneous heat production that the fuel cell stack should generate, and the corresponding minimum air path energy will be provided to prevent the reaction water from freezing inside the fuel cell stack and being completely carried away by the air.

[0082] If the fuel cell stack meets the low-temperature startup termination condition, the following step S170 is executed.

[0083] Step S170: indicating that the fuel cell system is successfully started at low temperature.

[0084] The fuel cell low-temperature start-up method provided in the embodiment of the present application pre-establishes a first mapping relationship among current, temperature and minimum air path energy and a second mapping relationship among current, temperature and minimum instantaneous heat production. First, the current of the fuel cell stack in the fuel cell system is set, and the current of the fuel cell stack is continuously increased until it is determined that the instantaneous heat production of the fuel cell stack at the current current and current temperature is not less than the minimum instantaneous heat production that the fuel cell stack should produce at the current current and current temperature determined in the second mapping relationship, and the final current of the fuel cell stack is obtained. In this process, the target minimum air path energy is also determined in the first mapping relationship at all times according to the fuel cell stack current and the corresponding temperature, and air is continuously introduced into the fuel cell stack based on the determined target minimum air path energy. According to the first mapping relationship, it can be seen that the target minimum air path energy is the air introduced into the fuel cell stack at the current and temperature corresponding to it, and the water produced by the reaction in the fuel cell stack is all carried by the air. The kinetic energy of the air during travel, according to the second mapping relationship, the minimum instantaneous heat production is the minimum instantaneous heat that the fuel cell stack should generate before all the water is carried away by the air to ensure that the water does not freeze. Therefore, when the current of the fuel cell stack is the final current and the temperature is the temperature corresponding to the final current, air will continue to be introduced into the fuel cell stack based on the target minimum air path energy determined at this time, and the instantaneous heat production at this time is not less than the minimum instantaneous heat production that the fuel cell stack should generate at this time, which can ensure that the water generated by the fuel cell stack reaction at this time does not freeze in the fuel cell stack and can be carried out by the air in time. When the fuel cell stack does not meet the preset low-temperature start-up end conditions, the above-mentioned final current will be adjusted to ensure that the instantaneous heat production of the fuel cell stack will not be less than the minimum instantaneous heat production that the fuel cell stack should generate, and provide the corresponding minimum air path energy to prevent the reaction water from freezing inside the fuel cell stack and being carried away by the air, thereby ensuring the successful start-up of the fuel cell system.

[0085] Furthermore, since the target minimum air path energy required by the fuel cell stack is determined according to the current and temperature of the fuel cell stack, and air is introduced into the fuel cell stack based on the determined target minimum air path energy, there is no need to supply excessive air path energy, which can effectively save the power consumption of the air path accessories of the fuel cell system and improve the energy utilization rate during the startup of the fuel cell system.

[0086] If the judgment result of step S150 is negative, the following steps may be performed:

[0087] Determine whether the fuel cell stack meets the preset low-temperature startup end condition.

[0088] If the fuel cell stack does not meet the low-temperature startup termination condition, the process returns to step S110 .

[0089] If the fuel cell stack meets the low-temperature startup end condition, it indicates that the low-temperature startup of the fuel cell system is successful.

[0090] Optionally, the temperature of the fuel cell stack may be calculated based on the heat generated by the fuel cell stack, the rotation speed of a cooling pump in the fuel cell system, and parameters of temperature sensors at the inlet and outlet of the fuel cell stack.

[0091] The present application embodiment provides another low temperature start method for a fuel cell system. Figure 3 The low temperature start-up method of the fuel cell system provided in the embodiment of the present application is described as follows: Figure 3 As shown, the method may include:

[0092] Step S200: setting the current of the fuel cell stack in the fuel cell system.

[0093] Step S210: Determine the current temperature of the fuel cell stack.

[0094] Step S220 : determining a target minimum air path energy corresponding to the current of the fuel cell stack and the temperature of the fuel cell stack at a current moment in a first mapping relationship among the preset current, temperature, and minimum air path energy.

[0095] Step S230: continuously introducing hydrogen into the anode of the fuel cell stack and continuously introducing air into the cathode of the fuel cell stack based on the target minimum air path energy.

[0096] The target minimum air path energy is the kinetic energy of the air required when all the water generated by the reaction between the air and the hydrogen in the fuel cell stack is carried away by the air.

[0097] Step S240: Determine the target minimum instantaneous heat production corresponding to the current of the fuel cell stack and the current temperature of the fuel cell stack in a second mapping relationship among the preset current, temperature and minimum instantaneous heat production.

[0098] The target minimum instantaneous heat generation is the minimum instantaneous heat that the fuel cell stack should generate before all the water is carried away by the air to ensure that the water does not freeze.

[0099] Step S250: Determine whether the current instantaneous heat generation of the fuel cell stack is less than the target minimum instantaneous heat generation.

[0100] The above steps S200-S250 are the same as steps S100-S150 in the aforementioned embodiment. Please refer to the above introduction for details and will not be repeated here.

[0101] If yes, execute the following step S260; if no, execute the following step S270.

[0102] Step S260: Increase the current of the battery stack according to the set step size, and return to execute the above step S210.

[0103] Specifically, if the current instantaneous heat production of the fuel cell stack is less than the target minimum instantaneous heat production required by the current fuel cell stack, it means that the current of the fuel cell stack is small at this time, resulting in insufficient instantaneous heat production of the fuel cell stack, so the current of the fuel cell stack is increased according to the set step value, and the process returns to execute the above step S210.

[0104] Step S270: Determine whether the fuel cell stack meets a preset low-temperature startup termination condition.

[0105] Specifically, if the current instantaneous heat production of the fuel cell stack is not less than the target minimum instantaneous heat production required by the current fuel cell stack, it means that the water generated by the fuel cell stack reaction does not freeze in the fuel cell stack and can be carried out by the air in time. It should be determined whether the fuel cell stack meets the preset low-temperature start-up end conditions.

[0106] If the fuel cell stack does not meet the low-temperature startup termination condition, the process returns to step S210 .

[0107] If the fuel cell stack meets the low-temperature startup termination condition, the following step S280 is executed.

[0108] Step S280: indicating that the fuel cell system is successfully started at low temperature.

[0109] Specifically, if the fuel cell stack does not meet the low-temperature startup termination conditions, since it is determined that the instantaneous heat production of the fuel cell stack is not less than the minimum instantaneous heat production that the fuel cell stack should generate, air will continue to be introduced into the fuel cell stack based on the target minimum air path energy corresponding to the final current, so the temperature of the fuel cell stack will increase. At this time, the above-mentioned steps of determining the temperature of the fuel cell stack at the current moment should be returned to ensure that the instantaneous heat production of the fuel cell stack will always be no less than the minimum instantaneous heat production that the fuel cell stack should generate, and the corresponding minimum air path energy will be provided to prevent the reaction water from freezing inside the fuel cell stack and being completely carried away by the air.

[0110] Optionally, in actual applications, the vehicle will request the system output power based on the vehicle speed, whether heating is on, the battery stack status, etc. When the system output power exceeds the value requested by the vehicle, under normal circumstances, the power battery will absorb the power. However, at low temperatures, the power battery has basically no ability to absorb power. At this time, the system output power is too large, which will charge the power battery and damage the power battery. Based on this, the embodiment of the present application provides another low-temperature starting method for a fuel cell system. Next, through the attached Figure 4 The low temperature start-up method of the fuel cell system of the present application is described as follows: Figure 4 As shown, the method may include:

[0111] Step S300: setting the current of the fuel cell stack in the fuel cell system.

[0112] Step S310: Determine the current temperature of the fuel cell stack.

[0113] Step S320 : determining a target minimum air path energy corresponding to the current of the fuel cell stack and the current temperature of the fuel cell stack in a first mapping relationship among the preset current, temperature, and minimum air path energy.

[0114] Step S330: continuously introducing hydrogen into the anode of the fuel cell stack and continuously introducing air into the cathode of the fuel cell stack based on the target minimum air path energy.

[0115] The target minimum air path energy is the kinetic energy of the air required when all the water generated by the reaction between the air and the hydrogen in the fuel cell stack is carried away by the air.

[0116] Step S340: Determine the target minimum instantaneous heat production corresponding to the current of the battery stack and the current temperature of the battery stack in a second mapping relationship among the preset current, temperature and minimum instantaneous heat production.

[0117] The target minimum instantaneous heat generation is the minimum instantaneous heat that the fuel cell stack should generate before all the water is carried away by the air to ensure that the water does not freeze.

[0118] Step S350: Determine whether the current instantaneous heat generation of the fuel cell stack is less than the target minimum instantaneous heat generation.

[0119] The above steps S300-S350 are the same as steps S100-S150 in the aforementioned embodiment. Please refer to the above introduction for details and will not be repeated here.

[0120] If so, execute the following step S360.

[0121] Step S360: Increase the current of the fuel cell stack according to the set step size until the current instantaneous heat production of the fuel cell stack calculated according to the increased current of the fuel cell stack is not less than the target minimum instantaneous heat production, and determine the power demand of the vehicle for the fuel cell system.

[0122] Specifically, in order to meet the power demand of the entire vehicle, the current of the fuel cell stack is increased according to the set step size until the current instantaneous heat production of the fuel cell stack calculated according to the increased current of the fuel cell stack is not less than the target minimum instantaneous heat production. It is also necessary to determine the power demand requested by the entire vehicle for the fuel cell system so as to adjust the output power of the fuel cell system according to the power demand to meet the power demand of the entire vehicle.

[0123] When the output power of the fuel cell system at the current moment is less than the required power, execute the following steps S370 and S390; when the output power of the fuel cell system at the current moment is equal to the required power, execute the following step S390; when the output power of the fuel cell system at the current moment is greater than the required power, execute the following steps S380 and S390.

[0124] Optionally, the process of determining the output power of the fuel cell system at the current moment may include:

[0125] Determine the first power of the fuel cell stack at the current moment.

[0126] Determine the second power consumed by other electrical components in the fuel cell system except the fuel cell stack at the current moment.

[0127] The output power of the fuel cell system at the current moment is obtained by subtracting the second power from the first power.

[0128] Specifically, the power of the fuel cell stack will not be fully used as the output power of the fuel cell system. This is because other electrical components in the fuel cell system besides the fuel cell stack will also consume a certain amount of the fuel cell stack power. The difference between the power of the fuel cell stack and the power consumed by other electrical components is the output power of the fuel cell system. Therefore, in order to determine the output power of the fuel cell system at the current moment, we can first determine the first power of the fuel cell stack at the current moment, and then determine the second power consumed by other electrical components in the fuel cell system besides the fuel cell stack at the current moment. Finally, subtract the second power from the first power to obtain the output power of the fuel cell system at the current moment.

[0129] Step S370: Increase the current of the fuel cell stack according to a set step size until the output power of the fuel cell system at the current moment obtained according to the increased current of the fuel cell stack is equal to the required power.

[0130] Specifically, the output power of the fuel cell system is related to the current of the fuel cell stack. The greater the current of the fuel cell stack, the greater the output power of the fuel cell stack, and the greater the output power of the fuel cell system. Therefore, if the output power of the fuel cell system at the current moment is less than the required power, the current of the fuel cell stack can be increased according to the set step size until the output power of the fuel cell system at the current moment obtained according to the increased current of the fuel cell stack is equal to the required power.

[0131] Step S380: Increase the target minimum air path energy at the current moment according to the set step size, and continue to introduce air into the fuel cell stack based on the increased target minimum air path energy until the output power of the fuel cell system at the current moment obtained according to the increased target minimum air path energy is equal to the required power.

[0132] Specifically, the output power of the fuel cell system is also related to the air path energy of the air introduced into the fuel cell stack. The greater the air path energy of the air introduced into the fuel cell stack, the greater the power consumption of other electrical components except the fuel cell stack, and the smaller the output power of the fuel cell system. Therefore, if the output power of the fuel cell system at the current moment is greater than the required power, the target minimum air path energy at the current moment can be increased according to the set step size, and air can be continuously introduced into the fuel cell stack based on the increased target minimum air path energy until the output power of the fuel cell system at the current moment obtained according to the increased target minimum air path energy is equal to the required power.

[0133] Step S390: Determine whether the fuel cell stack meets the preset low-temperature startup termination condition.

[0134] If the fuel cell stack does not meet the low-temperature startup termination condition, the process returns to step S310 .

[0135] If the fuel cell stack meets the low-temperature startup termination condition, the following step S400 is executed.

[0136] Step S400: indicating that the fuel cell system is successfully started at low temperature.

[0137] The above steps S390-S400 are the same as steps S270-S280 in the aforementioned embodiment. Please refer to the above introduction for details and will not be repeated here.

[0138] The fuel cell low-temperature start-up method provided in the embodiment of the present application not only determines the current of the fuel cell stack and the corresponding target minimum air path energy that can ensure the successful low-temperature start-up of the fuel cell, but also takes into account the required power of the entire vehicle. By increasing the current of the fuel cell stack and the target minimum air path energy, the output power of the fuel cell system is equal to the required power requested by the entire vehicle. While ensuring the successful low-temperature start-up of the fuel cell system, the power demand of the entire vehicle is met, avoiding damage to the power battery due to excessive output power of the fuel cell system.

[0139] In the embodiment of the present application, a process for determining the second mapping relationship among the current, temperature, and minimum instantaneous heat generation is introduced. The process may include:

[0140] Based on the preset currents and temperatures, the minimum instantaneous heat generation Q=n*(1.25-U)*I corresponding to each current and temperature is calculated respectively, wherein n is the number of cells in the battery stack, U is the maximum average cell voltage allowed by the battery stack at each current and temperature, and I is the current.

[0141] A second mapping relationship among each current, each temperature and each minimum instantaneous heat generation is established.

[0142] Specifically, because the minimum instantaneous heat production corresponding to different currents and temperatures is different, the embodiment of the present application presets each current and each temperature, and calculates the minimum instantaneous heat production corresponding to each current and each temperature. The minimum instantaneous heat production corresponding to different currents and different temperatures is related to the maximum average cell voltage allowed by the battery stack at different currents and different temperatures. First, the maximum average cell voltage allowed by the battery stack at each current and each temperature can be determined, and then the minimum instantaneous heat production Q=n*(1.25-U)*I corresponding to each current and each temperature can be calculated. Finally, a second mapping relationship between each current, each temperature, and each minimum instantaneous heat production can be established.

[0143] In the embodiment of the present application, the calculation process of the instantaneous heat generation of the above-mentioned stack is introduced, and the process may include:

[0144] Calculate the current instantaneous heat generation of the fuel cell stack as Q=n*(1.25-U)*I, where n is the number of cells in the fuel cell stack, U is the current average cell voltage of the fuel cell stack, and I is the current current of the fuel cell stack.

[0145] Specifically, to calculate the current instantaneous heat generation of the fuel cell stack, the current average voltage of the fuel cell stack can be measured, and then the current instantaneous heat generation of the fuel cell stack can be calculated based on the formula Q=n*(1.25-U)*I.

[0146] In the embodiment of the present application, the process of determining whether the fuel cell stack meets the preset low-temperature startup end condition is introduced. The process may include:

[0147] Determining whether the current temperature of the fuel cell stack is greater than a preset startup end temperature and whether the cumulative value of the instantaneous heat generation of the fuel cell stack is greater than the heat required for the system coolant and the fuel cell stack in the fuel cell system to rise from the temperature at the start of startup to above the startup end temperature;

[0148] If the current temperature of the fuel cell stack is greater than the start-up end temperature and the cumulative value of the instantaneous heat generation of the fuel cell stack is greater than the heat required for the system coolant in the fuel cell system and the fuel cell stack to rise from the temperature at the start of startup to above the start-up end temperature, it is determined that the fuel cell stack meets the preset low-temperature start-up end conditions.

[0149] Specifically, the start-up end temperature can be a temperature of zero degrees or above zero degrees and close to zero degrees. If the temperature of the fuel cell stack at the current moment is greater than the start-up end temperature, the temperature of the system coolant in the cooling subsystem of the fuel cell system may still be lower than the start-up end temperature. If the system coolant with a temperature below the start-up end temperature circulates into the fuel cell stack, it will also cause the temperature of the fuel cell stack to drop below the start-up end temperature. Therefore, only when the temperature of the fuel cell stack at the current moment is greater than the start-up end temperature and the cumulative value of the instantaneous heat production of the fuel cell stack is greater than the heat required for the system coolant and the fuel cell stack in the fuel cell system to rise from the temperature at the start of startup to above the start-up end temperature, can it be determined that the fuel cell stack meets the preset low-temperature start-up end conditions, that is, the low-temperature start-up of the fuel cell system is successful.

[0150] The low-temperature starting device for a fuel cell system provided in an embodiment of the present application is described below. The low-temperature starting device for a fuel cell system described below and the low-temperature starting method for a fuel cell system described above can be referenced to each other.

[0151] First, combine Figure 5 , introduce the low temperature starting device of fuel cell system, such as Figure 5 As shown, the low-temperature starting device of the fuel cell system may include:

[0152] The current setting unit 10 is used to set the current of the fuel cell stack in the fuel cell system;

[0153] A temperature determination unit 20 is used to determine the temperature of the fuel cell stack at a current moment;

[0154] a target minimum air path energy determination unit 30, configured to determine the target minimum air path energy corresponding to the current of the stack and the current temperature of the stack in a first mapping relationship among the preset current, temperature and minimum air path energy;

[0155] a gas introduction unit 40 for continuously introducing hydrogen into the anode of the stack and continuously introducing air into the cathode of the stack based on the target minimum air path energy, wherein the target minimum air path energy is the kinetic energy of the air required to carry away all water produced by the reaction of the air and the hydrogen in the stack;

[0156] a target minimum instantaneous heat production determination unit 50, configured to determine, from a preset second mapping relationship among current, temperature, and minimum instantaneous heat production, a target minimum instantaneous heat production corresponding to the current of the stack and the current temperature of the stack, wherein the target minimum instantaneous heat production is the minimum instantaneous heat production that the stack should generate to ensure that the water does not freeze before all the water is carried away by the air;

[0157] A heat generation determination unit 60 is configured to determine whether the current instantaneous heat generation of the stack is less than the target minimum instantaneous heat generation;

[0158] If yes, then the steps of the current adjustment unit 70 are executed as follows; if no, then the steps of the low temperature start end determination unit 80 are executed as follows;

[0159] a current adjustment unit 70, configured to increase the current of the stack according to a set step size and return to execute the steps of the temperature determination unit;

[0160] A low-temperature startup end judgment unit 80 is used to judge whether the fuel cell stack meets a preset low-temperature startup end condition;

[0161] If the fuel cell stack does not meet the low-temperature startup termination condition, the process returns to executing the steps of the temperature determination unit 20 ;

[0162] If the fuel cell stack meets the low-temperature startup end condition, the following steps of the startup success characterization unit 90 are executed;

[0163] The startup success indication unit 90 is used to indicate that the fuel cell system is successfully started at low temperature.

[0164] Optionally, the fuel cell system low-temperature starting device may further include:

[0165] A power demand determination unit, configured to determine the power demand of the fuel cell system by the entire vehicle;

[0166] a first power adjustment unit, configured to execute the steps of the low-temperature startup end judgment unit if the output power of the fuel cell system at a current moment is equal to the required power;

[0167] a second power adjustment unit configured to, if the output power of the fuel cell system at a current moment is less than the required power, increase the current of the fuel cell stack according to a set step size until the output power of the fuel cell system at the current moment obtained according to the increased current of the fuel cell stack is equal to the required power, and execute the steps of the low-temperature start end judgment unit;

[0168] The third power adjustment unit is used to increase the target minimum air path energy at the current moment according to the set step size if the output power of the fuel cell system at the current moment is greater than the required power, and continuously introduce air into the fuel cell stack based on the increased target minimum air path energy until the output power of the fuel cell system at the current moment obtained according to the increased target minimum air path energy is equal to the required power, and then execute the steps of the low-temperature start-up end judgment unit.

[0169] Optionally, the fuel cell system low-temperature starting device may further include:

[0170] Each minimum instantaneous heat generation determination unit is used to calculate the minimum instantaneous heat generation corresponding to each current and each temperature based on the preset current and each temperature, Q=n*(1.25-U)*I, where n is the number of cells in the battery stack, U is the maximum average cell voltage allowed by the battery stack at each current and each temperature, and I is the current;

[0171] The second mapping relationship establishing unit is used to establish a second mapping relationship among each current, each temperature and each minimum instantaneous heat generation.

[0172] Optionally, the fuel cell system low-temperature starting device may further include:

[0173] The current instantaneous heat generation calculation unit is used to calculate the current instantaneous heat generation of the battery stack Q=n*(1.25-U)*I, where n is the number of cells in the battery stack, U is the current average cell voltage of the battery stack, and I is the current current of the battery stack.

[0174] Optionally, the fuel cell system low-temperature starting device may further include:

[0175] a first power determining unit, configured to determine a first power of the fuel cell stack at a current moment;

[0176] a second power determination unit, configured to determine a second power consumed by other electrical components in the fuel cell system except the fuel cell stack at a current moment;

[0177] The output power determining unit is configured to subtract the second power from the first power to obtain the output power of the fuel cell system at a current moment.

[0178] Optionally, the process of the low-temperature startup end judgment unit judging whether the fuel cell stack meets a preset low-temperature startup end condition may include:

[0179] Determining whether the current temperature of the fuel cell stack is greater than a preset startup end temperature and whether the cumulative value of the instantaneous heat generation of the fuel cell stack is greater than the heat required for the system coolant and the fuel cell stack in the fuel cell system to rise from the temperature at the start of startup to above the startup end temperature;

[0180] If the current temperature of the fuel cell stack is greater than the start-up end temperature and the cumulative value of the instantaneous heat generation of the fuel cell stack is greater than the heat required for the system coolant in the fuel cell system and the fuel cell stack to rise from the temperature at the start of startup to above the start-up end temperature, it is determined that the fuel cell stack meets the preset low-temperature start-up end conditions.

[0181] The low-temperature starting device for a fuel cell system provided in the embodiments of the present application can be applied to low-temperature starting equipment for a fuel cell system. Figure 6 The hardware structure diagram of the low temperature starting device of the fuel cell system is shown. Figure 6 , the hardware structure of the fuel cell system 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;

[0182] 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;

[0183] 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;

[0184] 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;

[0185] 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 low-temperature startup solution for the fuel cell system.

[0186] 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 low-temperature startup scheme of the fuel cell system.

[0187] 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.

[0188] 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.

[0189] 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 low-temperature startup method for a fuel cell system, characterized in that: include: Setting the current of the fuel cell stack in the fuel cell system; Determining the current temperature of the fuel cell stack; Determining a target minimum air path energy corresponding to the current of the fuel cell stack and the current temperature of the fuel cell stack in a first mapping relationship among a preset current, a temperature, and a minimum air path energy; continuously passing hydrogen into the anode of the stack and continuously passing air into the cathode of the stack based on the target minimum air path energy, where the target minimum air path energy is the kinetic energy of the air required to carry away all water produced by the reaction of the air and the hydrogen in the stack; Determining a target minimum instantaneous heat production corresponding to the current of the fuel cell stack and the current temperature of the fuel cell stack in a preset second mapping relationship among current, temperature, and minimum instantaneous heat production, wherein the target minimum instantaneous heat production is the minimum instantaneous heat that the fuel cell stack should generate to ensure that the water does not freeze before all the water is carried away by the air; Determining whether the current instantaneous heat generation of the fuel cell stack is less than the target minimum instantaneous heat generation; If so, increasing the current of the battery stack according to a set step size until the current instantaneous heat generation of the battery stack calculated according to the increased current of the battery stack is not less than the target minimum instantaneous heat generation; Determining whether the fuel cell stack meets a preset low-temperature startup termination condition, the process of determining whether the fuel cell stack meets the preset low-temperature startup termination condition comprising: if the current temperature of the fuel cell stack is greater than the startup termination temperature and the cumulative value of the instantaneous heat generation of the fuel cell stack is greater than the heat required for the system coolant and the fuel cell stack in the fuel cell system to rise from the temperature at the start of startup to above the startup termination temperature, indicating that the low-temperature startup of the fuel cell system is successful; otherwise, returning to the step of determining the current temperature of the fuel cell stack; The process of determining the second mapping relationship among the current, the temperature and the minimum instantaneous heat generation includes: Based on the preset currents and temperatures, the minimum instantaneous heat generation corresponding to each current and temperature is calculated as Q=n*(1.25-U)*I, where n is the number of cells in the stack, U is the maximum average cell voltage allowed by the stack at each current and temperature, and I is the current; A second mapping relationship among each current, each temperature and each minimum instantaneous heat generation is established.

2. The method according to claim 1, characterized in that Before determining whether the fuel cell stack meets the preset low-temperature startup end condition, the method further includes: Determining the power demand of the fuel cell system for the entire vehicle; If the output power of the fuel cell system at the current moment is equal to the required power, determining whether the fuel cell stack meets the preset low-temperature startup end condition; If the output power of the fuel cell system at the current moment is less than the required power, the current of the fuel cell stack is increased according to a set step size until the output power of the fuel cell system at the current moment obtained according to the increased current of the fuel cell stack is equal to the required power, and it is determined whether the fuel cell stack meets the preset low-temperature startup end condition; If the output power of the fuel cell system at the current moment is greater than the required power, the target minimum air path energy at the current moment is increased according to the set step size, and air is continuously introduced into the fuel cell stack based on the increased target minimum air path energy until the output power of the fuel cell system at the current moment obtained according to the increased target minimum air path energy is equal to the required power, and then it is determined whether the fuel cell stack meets the preset low-temperature start-up end conditions.

3. The method according to claim 1, characterized in that The calculation process of the current instantaneous heat generation of the fuel cell stack includes: Calculate the current instantaneous heat generation of the fuel cell stack as Q=n*(1.25-U)*I, where n is the number of cells in the fuel cell stack, U is the current average cell voltage of the fuel cell stack, and I is the current current of the fuel cell stack.

4. The method according to claim 2, characterized in that The process of determining the output power of the fuel cell system at the current moment includes: Determining a first power of the fuel cell stack at a current moment; Determining a second power consumed by other electrical components in the fuel cell system except the fuel cell stack at a current moment; The output power of the fuel cell system at the current moment is obtained by subtracting the second power from the first power.

5. A low-temperature starting device for a fuel cell system, characterized in that: include: A current setting unit, used to set the current of the fuel cell stack in the fuel cell system; a temperature determination unit, configured to determine the current temperature of the fuel cell stack; a target minimum air path energy determination unit, configured to determine the target minimum air path energy corresponding to the current of the stack and the current temperature of the stack in a first mapping relationship among the preset current, temperature and minimum air path energy; a gas introduction unit, configured to continuously introduce hydrogen into the anode of the stack and continuously introduce air into the cathode of the stack based on the target minimum air path energy, wherein the target minimum air path energy is the kinetic energy of the air required to carry away all water produced by the reaction of the air and the hydrogen in the stack; a target minimum instantaneous heat production determination unit, configured to determine, from a preset second mapping relationship among current, temperature, and minimum instantaneous heat production, a target minimum instantaneous heat production corresponding to the current of the stack and the current temperature of the stack, wherein the target minimum instantaneous heat production is the minimum instantaneous heat that the stack should generate to ensure that the water does not freeze before all the water is carried away by the air; a heat generation determination unit, configured to determine whether the current instantaneous heat generation of the stack is less than the target minimum instantaneous heat generation; If yes, then execute the following steps of the current adjustment unit; if no, then execute the following steps of the low temperature start end judgment unit; a current adjustment unit, configured to increase the current of the fuel cell stack according to a set step size and return to execute the steps of the temperature determination unit; A low-temperature startup end judgment unit, used to judge whether the fuel cell stack meets a preset low-temperature startup end condition; If the current temperature of the fuel cell stack is greater than the startup end temperature and the cumulative value of the instantaneous heat generation of the fuel cell stack is greater than the heat required for the system coolant and the fuel cell stack in the fuel cell system to rise from the temperature at the start of startup to above the startup end temperature, then the steps of the following startup success characterization unit are executed; otherwise, the process returns to the steps of the temperature determination unit; A startup success characterization unit, used to characterize the success of the low-temperature startup of the fuel cell system; A second mapping relationship establishing unit, used to establish a second mapping relationship between each current, each temperature and each minimum instantaneous heat generation; The device is also used to calculate the minimum instantaneous heat generation Q=n*(1.25-U)*I corresponding to each current and each temperature based on the preset current and each temperature, wherein n is the number of cells in the battery stack, U is the maximum average cell voltage allowed by the battery stack at each current and each temperature, and I is the current.

6. The device according to claim 5, characterized in that Also includes: A power demand determination unit, configured to determine the power demand of the fuel cell system by the entire vehicle; a first power adjustment unit, configured to execute the steps of the low-temperature startup end judgment unit if the output power of the fuel cell system at a current moment is equal to the required power; a second power adjustment unit configured to, if the output power of the fuel cell system at a current moment is less than the required power, increase the current of the fuel cell stack according to a set step size until the output power of the fuel cell system at the current moment obtained according to the increased current of the fuel cell stack is equal to the required power, and execute the steps of the low-temperature start end judgment unit; The third power adjustment unit is used to increase the target minimum air path energy at the current moment according to the set step size if the output power of the fuel cell system at the current moment is greater than the required power, and continuously introduce air into the fuel cell stack based on the increased target minimum air path energy until the output power of the fuel cell system at the current moment obtained according to the increased target minimum air path energy is equal to the required power, and then execute the steps of the low-temperature start-up end judgment unit.

7. A fuel cell system low temperature starting device, characterized in that: including memory and processor; The memory is used to store programs; The processor is used to execute the program to implement each step of the low-temperature startup method of the fuel cell system according to any one of claims 1 to 4.

8. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, each step of the low-temperature startup method for a fuel cell system according to any one of claims 1 to 4 is implemented.

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