Hydrogen energy fuel cell system and low-temperature cold start method thereof

Abstract

The invention relates to the technical field of fuel cell control, discloses a hydrogen energy fuel cell system and a low-temperature cold start method thereof, and aims to solve the problem of start failure caused by the fact that the water production rate is not matched with the temperature rise rate and the interior of a fuel cell is iced in the existing cold start process. The method specifically comprises the following steps: discharging liquid water in the electric pile by executing shutdown purging; two-stage exponential current loading is adopted, slow preheating is achieved in the first stage, rapid heating is achieved through current accelerated growth in the second stage, it is guaranteed that current at a switching point is continuous and smooth, and current sudden change impact is avoided; and a charge constraint step: calculating and controlling the total charge to meet the system energy consumption budget.Based on the method, the temperature rise and water production matching of the fuel cell can be effectively improved in the low-temperature cold start process, the icing risk is reduced, the cold start success rate and the system stability are improved, and the service life of the fuel cell is prolonged; the method is suitable for a low-temperature cold start scene of a vehicle-mounted proton exchange membrane fuel cell.

Description

Technical Field

[0001] This invention relates to the field of fuel cell control technology, and in particular to a hydrogen energy fuel cell system and its low-temperature cold start method. Background Technology

[0002] Hydrogen fuel cells have become an important energy technology in the automotive, drone, and backup power sectors due to their high power density, zero carbon emissions, and excellent dynamic response characteristics. Among them, proton exchange membrane fuel cells (PEMFCs) are the most widely used due to their advantages such as low operating temperature, small size, and fast start-up. However, when starting up in low-temperature environments (such as -30°C), the water generated by the electrochemical reaction is prone to freezing in the cathode catalyst layer and gas diffusion layer. This leads to obstruction of gas transport channels, occupation of electrode reaction sites, increased internal resistance of the cell, and ultimately causes performance degradation or even physical damage to the stack, severely limiting its application in cold regions.

[0003] Currently, the mainstream cold-start control methods for fuel cell systems mainly include two core schemes: linear current loading strategy and stepped current loading strategy. The linear current loading strategy aims to increase the current applied to the stack uniformly and continuously over time. This continuous and gradual current injection promotes the gradual occurrence of electrochemical reactions within the stack, guiding the stack temperature to rise slowly and uniformly. Its significant advantage lies in its extremely simple and direct control logic, making it easy to implement. However, the fundamental drawback of this gradual heating method is its relatively slow heating rate. Due to the insufficient heating speed, key battery components such as the catalyst layer and proton exchange membrane are exposed to sub-freezing temperatures for extended periods. This sustained low temperature state can easily lead to serious consequences in the later stages of the cold start process: large amounts of generated and accumulated liquid water cannot be discharged or evaporated in time, rapidly freezing to form ice crystals. The consequences of freezing are catastrophic, significantly hindering the diffusion and transport of reactant gases (such as hydrogen and oxygen) to the catalyst active sites, ultimately leading to a sharp deterioration in battery performance (such as a voltage drop), and in severe cases, even causing the entire cold start process to fail.

[0004] Stepped current loading strategy: This strategy addresses the shortcomings of linear loading strategies by dividing the entire current loading process into multiple discrete stages. Within each stage, the current applied to the battery stack is maintained at a constant preset value for a predetermined time. Theoretically, this "jump-hold" pattern can achieve a segmented heating effect, allowing for some adjustment and recovery of the battery's internal state during the current plateau period, thus improving the stability of the cold start process. However, this strategy also has insurmountable drawbacks: when the current jumps from one step to the next higher step, it instantly disrupts the battery's original, relatively fragile hydrothermal equilibrium. This abrupt change causes a severe mismatch between the rate of water production from the electrochemical reaction and the rate of temperature rise due to ohmic heat and reaction heat. At the instant of the current jump, the water production rate may far exceed the freezing point suppression capability supported by the temperature rise, greatly increasing the risk of water freezing in critical areas (such as the cathode catalyst layer) during the early stages of cold start.

[0005] Patent CN111785992A discloses a hybrid low-temperature cold start control method for fuel cell vehicles. It divides the cold start process into two stages. The first stage, Cold Start Stage 1, involves external heating elements, the power battery, and system waste heat working together to supply fuel. Once the fuel cell reaches its startable temperature, the second stage, the hybrid start stage, begins. During this stage, the air supply unit and hydrogen supply unit operate, and the fuel cell operates at low power. However, this cold start method is based on the coupling of external heating, power system waste heat recovery (battery / motor / electronic control), and fuel cell self-start. It emphasizes the coupling management of the fuel cell system's own cold start control with the thermal management control of other vehicle components, effectively utilizing system preheating and fully exploring the system's energy-saving potential. Patent CN114583211A discloses a fuel cell system and a low-temperature start method for the fuel cell system. Although it discloses a two-stage pneumatic approach, it relies on an external heating system to heat the fuel cell to a set temperature before starting the fuel cell.

[0006] In summary, existing cold start control methods all suffer from problems such as unreasonable matching of heating rate and water production rate, local overcooling or overheating, and easy icing and blockage of the cathode catalyst layer, making it difficult to simultaneously achieve rapid heating, icing suppression, and system stability. Therefore, there is an urgent need for a novel cold start strategy that optimizes the current loading rate in stages and coordinates the dynamics of stack heating and water production to improve the success rate and lifespan of hydrogen fuel cell systems in low-temperature environments. Summary of the Invention

[0007] This invention aims to overcome the shortcomings of existing fuel cell cold start technologies and provides a low-temperature cold start method for hydrogen energy fuel cell systems. This method addresses the problems of mismatch between water production rate and heating rate, easy local icing of the catalyst layer, uneven temperature distribution of the fuel cell, and high start-up failure rate in low-temperature environments caused by existing current loading strategies. The invention proposes a low-temperature cold start method that is simple to operate, precise to control, and requires no external heating, thereby significantly improving the start-up success rate and operational stability of the system under extremely cold conditions.

[0008] To achieve the above objectives, in a first aspect, the present invention provides a low-temperature cold start method for a hydrogen fuel cell system, which combines shutdown purge initialization with total charge constraint to achieve synergistic optimization of thermal management and water management, including the following steps: Purge the fuel cell system while it is powered off to remove residual liquid water from the fuel cell catalyst layer, gas diffusion layer, and flow channels, thus initializing the fuel cell system to a state where there is no visible liquid water and no external heating conditions. A two-stage exponential current loading strategy is used to control the change of fuel cell current over time. In the first stage, the current changes from 0 to... t s During the transition period, the current increases exponentially according to the first stage; in the second stage, during the transition period... t s Subsequently, the current increases exponentially according to the second stage, causing the stack temperature to rise above the freezing point; the current growth rate in the first stage is lower than that in the second stage; the currents in the first and second stages change during the transition time. t s The magnitude and slope of the current are continuous. During the cold start process, the current loading satisfies the total charge input constraint.

[0009] Furthermore, purging in the shutdown state includes: maintaining the hydrogen flow rate at idle speed, increasing the air flow rate to perform the first stage of purging; connecting the air bypass and continuing to maintain the hydrogen flow rate to perform the second stage of purging; stopping purging when the high-frequency impedance value of the fuel cell stack is higher than a preset threshold.

[0010] Furthermore, the current loading expression is:

[0011] in, I ( t )express t The magnitude of the current at any given moment. A This is the amplitude coefficient for the first stage. k 1 represents the first-stage index growth rate. k 2 represents the second-stage exponential growth rate. t sThis is the transition period between Phase One and Phase Two. t max The total time for applying the first-stage current and the second-stage current is given. I s To switch the current value at different times, C This is used to ensure the continuity of the function at the switching point.

[0012] Furthermore, the first-stage exponential growth rate k 1 and the second stage exponential growth rate k The value of 2 depends on the activation area of ​​the fuel cell, the rated current, and the heating rate required for cold start.

[0013] Furthermore, the amplitude coefficient of the first stage A Calculated using the following formula:

[0014] in, k 1 represents the first-stage index growth rate. I s To switch time points t s The current value at a given time.

[0015] Furthermore, switching time t s The value ranges from 30% to 70% of the total loading time, and is determined based on the matching relationship between the expected heating rate and water production during fuel cell cold start.

[0016] Furthermore, the coefficient C Calculated using the following formula:

[0017] in, k 1 represents the first-stage index growth rate. k 2 represents the second-stage exponential growth rate. t s This is for switching time.

[0018] Furthermore, the total charge input constraint is achieved by integrating the total charge. Q total This indicates the total integrated charge. Q total Calculated using the following formula:

[0019] in, Q total The charge obtained by integrating the current during the entire cold start process must meet the preset target charge requirement. A This is the amplitude coefficient for the first stage. k1 represents the first-stage index growth rate. k 2 represents the second-stage exponential growth rate. t s This is the transition period between Phase One and Phase Two. C For the second stage current coefficient, t max This represents the total time for the first-stage current and the second-stage current to be applied.

[0020] Furthermore, during the cold start process of the fuel cell system, after the fuel cell current rises from 0A at the initial moment to the maximum current, it continues to operate at the maximum current.

[0021] Furthermore, temperature, current, and voltage are acquired in real time using temperature, current, and voltage sensors in the hydrogen fuel cell system, and parameters are dynamically adjusted based on real-time temperature, current, and voltage feedback. A , k 1. k 2. t s and C Optimize the matching between the target temperature rise rate and the water production rate.

[0022] Secondly, the present invention can provide a hydrogen energy fuel cell system, specifically an on-board proton exchange membrane fuel cell system, which adopts the low-temperature cold start method of the above-mentioned hydrogen energy fuel cell system for cold start, and the operating temperature range is -30°C to 0°C.

[0023] Furthermore, the first stage is the warm-up stage: from 0~ t s During the transition period, the current follows an exponential function of the first stage. Slow growth to achieve a gentle temperature increase, avoiding rapid water production that could cause the catalyst layer to freeze; the second stage is the accelerated heating stage: during the transition time t s Then, according to the second exponential growth rate k 2. Apply the second stage current. The rate of current increase gradually slows down, allowing for continuous heat accumulation and a rapid rise in the stack temperature above freezing. This reduces the risk of localized overheating and ice blockage, enabling rapid startup. The transition time between the first-stage and second-stage currents... t s The magnitude and slope of the current are continuous to avoid sudden current surges that could impact the fuel cell system.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention achieves continuous current control during low-temperature cold start-up through a two-stage exponential current loading strategy. The first stage is the preheating stage: from 0~ t sDuring the transition period, the current increases slowly according to the first stage exponential function to achieve a gentle temperature rise and avoid rapid water production that could cause the catalyst layer to freeze; the second stage is the accelerated temperature rise stage: during the transition period t s Then, according to the second exponential growth rate k 2. Applying the second-stage current, the rate of current increase gradually slows down, allowing for continuous heat accumulation and rapidly raising the stack temperature above freezing. This reduces the risk of local overheating and ice blockage, enabling rapid startup. It overcomes the shortcomings of single-stage linear loading strategies, such as low heating rate, easy icing, and high risk of startup failure. It has significant advantages such as high startup success rate, good system stability, and simple algorithm implementation. Moreover, it does not require external heating for low-temperature cold startup, making it suitable for application in the field of cold startup of on-board hydrogen fuel cell systems. Attached Figure Description

[0025] To more intuitively and clearly illustrate the technical solutions and advantages of the embodiments of the present invention, the accompanying drawings used in the embodiments are briefly introduced below.

[0026] Figure 1 This is a schematic diagram of the working process of a low-temperature cold start method for a hydrogen fuel cell system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram showing the current change over time in a low-temperature cold start method for a hydrogen fuel cell system according to an embodiment of the present invention. Figure 3 This is a schematic diagram showing the comparison of output voltage between a low-temperature cold start method and a linear current loading strategy for a hydrogen fuel cell system in an embodiment of the present invention. Figure 4 This is a schematic diagram showing the comparison of the ice volume fraction in the cathode catalyst layer between a low-temperature cold start method and a linear current loading strategy for a hydrogen fuel cell system in an embodiment of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention provides a flowchart of a low-temperature cold start method for a hydrogen fuel cell system, as shown in the attached diagram. Figure 1 As shown, the low-temperature cold start method for this hydrogen fuel cell system includes the following steps: Step 1: Initialization steps.

[0029] Before starting the fuel cell system in a low-temperature environment, the system controller first obtains the current fuel cell temperature and confirms the cold start conditions (e.g., the ambient temperature is below a set threshold and the stack temperature is close to the ambient temperature). This ensures that the fuel cell system does not have external auxiliary heating and relies solely on the electrochemical reaction of the fuel cell itself to generate heat, thereby improving the energy efficiency and structural simplification of the fuel cell system. To prevent residual liquid water from freezing and causing gas path blockage under low-temperature conditions, a two-stage shutdown purging process is executed to remove residual liquid water in the membrane electrode, gas diffusion layer, and bipolar plates, thus avoiding freezing and ensuring that there is no visible liquid water inside the stack in the initial state, reducing the risk of ice blockage during cold start. Specifically, the process includes: maintaining the hydrogen flow rate at idle (typically 10%~20% of the rated hydrogen flow rate), while simultaneously increasing the air compressor speed to deliver high-flow air to the cathode side for the first stage of purging. This stage utilizes the strong airflow to forcibly remove moisture from the membrane electrode assembly and gas diffusion layer, focusing on removing easily flowing water and surface-adhered water, typically lasting 10~20 seconds. Subsequently, the air compressor speed is reduced, the intake throttle valve and back pressure valve are closed to reduce the cathode side pressure and prevent condensate from flowing back to the catalyst layer. The air bypass valve is then opened to allow air to flow through the bypass path, reducing the gas path pressure difference while maintaining the hydrogen flow rate for the second stage of purging to further remove residual moisture. This stage primarily targets moisture removal from the microporous structure and dead corners of the flow channels, typically lasting 5~15 seconds. The high-frequency impedance value of the fuel cell stack is detected by electrochemical impedance spectroscopy. When the high-frequency impedance value of the fuel cell stack exceeds a preset threshold, it indicates that there is no conductive water film left in the stack, at which point purging is stopped, and the shutdown process is completed.

[0030] Step Two: Current Loading Step. A two-stage exponential current loading strategy is used to control the current variation over time. The specific expression is as follows: (1) in, A The first-stage amplitude coefficient is determined by the formula. Calculations are performed to ensure that the current at the end of the first stage is continuous with the switching point. k 1. The first stage current exponential growth rate, k 2 represents the exponential growth rate of the second-stage current. k 1. Used to control the current growth rate during the preheating stage. k 2. This is used to control the current growth rate during the accelerated heating phase, and is determined based on the matching of the fuel cell activation area, rated current, and the heating rate required for cold start. It can be determined based on thermal and electrochemical models. k 1 and k 2, if k 1. Selecting a smaller value can control the initial heating rate to be raised to near the freezing point without causing excessive water production; k 2 slightly greater than kA value of 1 or equivalent can accelerate the heating rate while avoiding localized overheating. In practice, optimization is usually achieved through experimental calibration at different ambient temperatures (e.g., -30℃, -20℃). k 1 and k 2. Two coefficients; t s This refers to the switching time between the first and second stages, ranging from 30% to 70% of the total loading time. It can be calculated based on the ambient temperature, the reactor's thermal capacity, and the difference between the freezing point and the reactor core temperature. I s For switching time t s The current value at time t is calculated from the function in the first stage. C The second-stage amplitude coefficient is determined by the formula. calculate, C This is used to ensure a smooth and continuous switching point.

[0031] In 0~ t s During the time period, the current increases slowly according to the first-stage exponential function, achieving a gentle temperature rise and preventing localized freezing of the cathode catalyst layer and gas diffusion layer due to excessive water generation, thus ensuring unobstructed battery reaction sites. t s Subsequently, the current continues to be applied according to the exponential function of the second stage, with the growth rate gradually slowing down and eventually stabilizing. This allows for continuous heat accumulation, accelerating the temperature rise of the fuel cell system above freezing point and maintaining dynamic matching between the current and the produced water, reducing the risk of ice blockage. The current curves switching between the first and second stages are continuous and smooth, avoiding the water-thermal imbalance caused by step loading, thereby improving the stability and success rate of low-temperature start-up of the fuel cell.

[0032] Step 3: Charge Constraint. To meet the cold start energy budget and heating requirements, the total integrated charge during the entire cold start process is constrained. Q total To meet the preset target, the following formula is used for calculation: (2) The first integral represents the charge accumulation in the first stage, and the second integral represents the charge accumulation in the second stage, ensuring that the total charge in both stages matches the cold start thermal requirements. If the calculation results do not meet the requirements, adjustments can be made. t max , t s or k 1. k 2. Iterative optimization of parameters until the design goal is achieved.

[0033] In implementing this invention, the two-stage exponential current loading strategy can be embedded into the main controller of the fuel cell system as a software control algorithm. The main controller establishes a high-speed data acquisition channel with temperature, current, and voltage sensors to acquire key operating parameters such as temperature, actual current, and voltage during fuel cell stack operation in real time. During cold start, the controller compares and analyzes the real-time acquired ambient and stack temperatures with preset start-up parameters, dynamically calculating and updating the core parameters of the two-stage current loading strategy. A , k 1. k 2. t s and C The system outputs a target current command to the DC / DC converter, and the power regulation control module accurately tracks the current curve, ensuring that the error between the actual loaded current and the theoretically set two-stage exponential curve remains within the allowable range. Furthermore, during loading, temperature sensors continuously monitor temperature trends at key locations on the fuel cell stack (such as the reactant gas inlet / outlet and near the cathode catalyst layer). Once the overall stack temperature is detected to be stably above the freezing point threshold and the rate of temperature rise meets subsequent operational requirements, the controller issues a mode switching command, smoothly switching the system operating state from cold start mode to idle mode. In idle mode, the fuel cell maintains a lower load output, thereby reducing thermal shock and power fluctuations in the stack, providing stable transition conditions for subsequent normal operation.

[0034] For example, for a single-cell fuel cell, under a cold start condition of -30°C, if the desired final current of the first stage is... I s The first phase switching time is 0.08A. t s For 50 seconds, exponential growth rate k 1= k 2 = 0.1147s -1 Then, according to the formula above, we can calculate: First stage amplitude coefficient A The calculation formula is: (3) Substituting the parameters, we get:

[0035] Second stage amplitude coefficient C The calculation formula is: (4) Substituting the parameters, we get:

[0036] Based on calculationsA , C , k 1. k 2. t s The parameters, and the resulting curves showing the specific current changing over time, are attached. Figure 2 As shown. Proceed to step three to calculate the total integrated charge during the entire cold start process. Q total Verify whether it meets the preset cold start energy requirement target. If the calculation result... Q total If the target value is not met, the total current loading time needs to be adjusted. t max or exponential growth rate k 1. k The two parameters are calculated iteratively until the total integrated charge meets the system's cold start design requirements. In practical applications, the controller can automatically adjust these parameters based on the ambient temperature, the fuel cell system's thermal capacity, and the target cold start heating rate to achieve optimal cold start performance.

[0037] Through the above embodiments, the present invention demonstrates significant performance advantages in the low-temperature cold start process of fuel cell systems, as detailed in the appendix. Figure 3 As shown, compared with the current mainstream linear current loading strategy, under the same ambient temperature and operating conditions, the control method of this invention can significantly extend the time for the fuel cell system to maintain a stable output voltage, with a voltage drop time delay of more than 20 seconds. This effectively avoids the rapid voltage decay and cold start interruption problems caused by the slow temperature rise of the fuel cell system in traditional methods, thus improving the reliability and success rate of the system's low-temperature cold start. After the cold start, the output voltage of the fuel cell system is increased by more than 4% compared with the linear loading method, improving the stack output performance after the cold start.

[0038] Furthermore, by rationally setting the current growth rate and switching time of the first and second stages, this invention significantly reduces the ice volume fraction of the fuel cell cathode catalyst layer compared to the traditional linear loading strategy, as shown in the attached figure. Figure 4 As shown, after the cold start, the ice volume fraction of the cathode catalyst layer decreased by more than 9%, which effectively suppressed the risk of local icing and gas transport channel blockage caused by excessively fast water production rate during the low-temperature cold start process, reduced the failure probability of electrode active sites, prevented performance degradation and irreversible damage of fuel cell system, and significantly extended the service life of fuel cell system.

[0039] Based on the above embodiments, the present invention can also provide a hydrogen energy fuel cell system, specifically an on-board proton exchange membrane fuel cell system, which adopts the low-temperature cold start method of the above hydrogen energy fuel cell system for cold start, and the operating temperature range is -30°C to 0°C.

[0040] The invention also provides a control system for a hydrogen fuel cell system, including a controller, a DC / DC converter, a temperature sensor, a current sensor, and a voltage sensor. The controller embeds the low-temperature cold start method for the hydrogen fuel cell system described in this invention. The temperature sensor, current sensor, and voltage sensor are used to monitor the temperature, current, and voltage of the fuel cell stack in real time. The controller sends a purging command to the purging mechanism of the hydrogen fuel cell system and issues a current adjustment command to the DC / DC converter according to the current loading expression.

[0041] The current loading expression is: .

[0042] The controller also dynamically adjusts parameters based on real-time temperature, current, and voltage feedback. A , k 1. k 2. t s and C Optimize the matching between the target temperature rise rate and the water production rate.

[0043] Furthermore, during the cold start process of the fuel cell system, after the fuel cell current rises from 0A at the initial moment to the maximum current, the controller sends a command to the DC / DC converter to continue operating at the maximum current.

[0044] In summary, this invention achieves continuous current control during low-temperature cold start-up through a two-stage exponential current loading strategy, overcoming the shortcomings of single-stage linear loading strategies such as low heating rate, easy icing, and high risk of start-up failure. It has significant advantages such as high start-up success rate, good system stability, and simple algorithm implementation, making it suitable for application in the field of cold start-up of on-board hydrogen fuel cell systems.

[0045] The above description is merely a preferred embodiment of the present invention, used to illustrate the technical solution and advantages of the present invention. However, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A low-temperature cold start method for a hydrogen fuel cell system, characterized in that, Includes the following steps: Purge the fuel cell while it is powered off to remove the liquid water inside and initialize the fuel cell system to a state without external heating. A two-stage exponential current loading strategy is used to control the change of fuel cell current over time. In the first stage, the current changes from 0 to... t s During the transition period, the current increases exponentially according to the first stage; in the second stage, during the transition period... t s Subsequently, the current increases exponentially according to the second stage, causing the stack temperature to rise above the freezing point; the current growth rate in the first stage is lower than that in the second stage; the currents in the first and second stages change during the transition time. t s The magnitude and slope of the current are continuous. During the cold start process, the current loading satisfies the total charge input constraint.

2. The low-temperature cold start method for a hydrogen fuel cell system according to claim 1, characterized in that, Purge in the off state includes: maintaining hydrogen flow at idle speed, increasing air flow for the first stage of purging; connecting the air bypass and continuing to maintain hydrogen flow for the second stage of purging; stopping purging when the high-frequency impedance value of the fuel cell stack exceeds a preset threshold.

3. The low-temperature cold start method for a hydrogen fuel cell system according to claim 1, characterized in that, The current loading expression is: in, I ( t )express t The magnitude of the current at any given moment. A This is the amplitude coefficient for the first stage. k 1 represents the first-stage index growth rate. k 2 represents the second-stage exponential growth rate. t s This is the transition period between Phase One and Phase Two. t max The total time for applying the first-stage current and the second-stage current is given. I s To switch the current value at different times, C Used to ensure the continuity of the function at the switching point; first-stage exponential growth rate k 1 and the second stage exponential growth rate k The value of 2 depends on the activation area of ​​the fuel cell, the rated current, and the heating rate required for cold start.

4. The low-temperature cold start method for a hydrogen fuel cell system according to claim 3, characterized in that, First stage amplitude coefficient A Calculated using the following formula: in, k 1 represents the first-stage index growth rate. I s To switch time points t s The current value at a given time.

5. The low-temperature cold start method for a hydrogen fuel cell system according to any one of claims 1 to 4, characterized in that, Switching Time t s The value ranges from 30% to 70% of the total loading time, and is determined based on the matching relationship between the expected heating rate and water production during fuel cell cold start.

6. The low-temperature cold start method for a hydrogen fuel cell system according to claim 3 or 4, characterized in that, coefficient C Calculated using the following formula: in, k 1 represents the first-stage index growth rate. k 2 represents the second-stage exponential growth rate. t s This is for switching time.

7. The low-temperature cold start method for a hydrogen fuel cell system according to claim 3 or 4, characterized in that, Total charge input constraint using integrated total charge Q total This indicates the total integrated charge. Q total Calculated using the following formula: in, Q total The charge obtained by integrating the current during the entire cold start process must meet the preset target charge requirement. A This is the amplitude coefficient for the first stage. k 1 represents the first-stage index growth rate. k 2 represents the second-stage exponential growth rate. t s This is the transition period between Phase One and Phase Two. C For the second stage current coefficient, t max This represents the total time for the first-stage current and the second-stage current to be applied.

8. The low-temperature cold start method for a hydrogen fuel cell system according to claim 7, characterized in that, During the cold start process of a fuel cell system, the fuel cell current rises from 0A at the initial moment to the maximum current and then continues to operate at the maximum current.

9. The low-temperature cold start method for a hydrogen fuel cell system according to claim 3 or 4, characterized in that, Temperature, current, and voltage are acquired in real time by temperature sensors, current sensors, and voltage sensors in the hydrogen fuel cell system, and parameters are dynamically adjusted based on real-time temperature, current, and voltage feedback. A , k 1. k 2. t s and C Optimize the matching between the target temperature rise rate and the water production rate.

10. A hydrogen fuel cell system, characterized in that, For a vehicle-mounted proton exchange membrane fuel cell system, a low-temperature cold start method for a hydrogen energy fuel cell system as described in any one of claims 1-9 is used for cold start, with an operating temperature range of -30°C to 0°C.

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