Fuel cell cathode rapid lifting and loading system and control method thereof

Abstract

The invention belongs to the technical field of battery management, and particularly relates to a fuel cell cathode rapid lifting and loading system and a control method thereof, the fuel cell cathode rapid lifting and loading system comprises an air filter, an air compressor, an intercooler, a humidifier, a tail exhaust, a rapid lifting and loading valve, a dry air inlet valve, a wet air inlet valve, a humidifier humidity regulating valve, a back pressure valve and a control unit; according to the invention, the quick lifting and loading valve is additionally arranged between the intercooler and the tail exhaust, so that excess air generated by acceleration of the air compressor can be directly bypassed to the tail exhaust during lifting and loading, the problem of unsmooth exhaust caused by mismatching of response speeds of the air compressor and the back pressure valve is effectively solved, and the lifting and loading time of the fuel cell from low power to high power is remarkably shortened; under the working condition of load reduction, the valve can quickly discharge redundant air, and can be matched with accurate down-regulation of the rotating speed of an air compressor to realize quick falling of the electric pile power, so that the dynamic response requirement of a whole vehicle power system is met.

Description

Technical Field

[0001] This invention belongs to the field of battery management technology, specifically relating to a rapid load increase / decrease system for a fuel cell cathode and its control method. Background Technology

[0002] The cathode system of a fuel cell is responsible for supplying the stack with air that meets the requirements for flow rate, pressure, and humidity; its performance directly affects the dynamic response characteristics of the fuel cell. Existing cathode systems typically employ a series structure of "air compressor-intercooler-humidifier-stack-back pressure valve-exhaust," such as... Figure 1 As shown, the moisture carried by the gas after the reaction is recovered and reused by a humidifier, and then discharged into the atmosphere after the pressure is regulated by a back pressure valve. Although this scheme has a simple structure, it has obvious defects in practical applications.

[0003] First, the mismatch in response speed between the air compressor and the back pressure valve results in a slow rate of load increase and decrease in the fuel cell stack, leading to a prolonged process from low to high power. Second, when the fuel cell is used in a vehicle, braking requires rapid load reduction to decrease the charging rate of the battery. However, due to the limited load reduction rate, the fuel cell output power cannot decrease in time. With the added effect of kinetic energy recovery, the battery charging rate can reach 6C, far exceeding the 2C level during normal driving. This high-current charging severely damages battery life. More critically, the existing system lacks independent adjustment mechanisms for the flow rate and humidity of the incoming air and the humidifier's humidification capacity. Relying solely on the back pressure valve makes it difficult to achieve multi-objective coordinated control, failing to meet the dual requirements of rapid dynamic adjustment and battery protection for the fuel cell. Summary of the Invention

[0004] To address the aforementioned shortcomings of the prior art, this invention provides a rapid load-lifting system for fuel cell cathodes and its control method.

[0005] In a first aspect, the present invention provides a rapid loading and unloading system for a fuel cell cathode, comprising an air filter, an air compressor, an intercooler, a humidifier, an exhaust, a rapid loading and unloading valve, a dry air intake valve, a wet air intake valve, a humidifier humidity regulating valve, a back pressure valve, and a control unit. The air filter's air inlet is connected to the outside atmosphere, and its air outlet is connected to the air inlet of the fuel cell stack via an air compressor, intercooler, and humidifier. A dry air intake valve is installed on the pipeline between the fuel cell stack's air inlet and the intercooler, and a wet air intake valve is installed on the pipeline between the humidifier's first air outlet and the fuel cell stack's air inlet. A back pressure valve is installed on the pipeline between the humidifier's second air outlet and the vehicle's exhaust. The fuel cell stack's air outlet is connected to the humidifier's second air inlet, and a humidifier humidity control valve is installed on the pipeline between the fuel cell stack's air outlet and the back pressure valve's air inlet. A quick-lift valve is installed on the pipeline between the intercooler and the exhaust. The control unit is electrically connected to the rapid lifting load valve, dry air intake valve, wet air intake valve, humidifier humidity regulating valve, and back pressure valve, respectively, and is used to adjust the opening of each valve according to the power change requirements of the fuel cell.

[0006] Secondly, the present invention provides a control method applicable to the above-described fuel cell cathode rapid load increase / decrease system, comprising: S1. Monitor changes in fuel cell power demand in real time to determine whether it enters a rapid load increase or rapid load decrease condition. S2. When it is determined that the rapid load increase condition has been entered, the rapid load increase control process is executed to adjust the opening of the rapid load increase valve, back pressure valve, dry air intake valve, wet air intake valve and humidifier humidity control valve. S3. When it is determined that the rapid load reduction condition has been entered, the rapid load reduction control process is executed to adjust the opening of the rapid load reduction valve, back pressure valve, dry air intake valve, wet air intake valve and humidifier humidity control valve. S4. The opening degree of each valve is optimized by using a pre-stored predictive control algorithm to ensure that the inlet air pressure and air flow of the fuel cell stack track the target value and meet the system constraints.

[0007] Further improvements to this technical solution include the following method in step S1 for real-time monitoring of changes in fuel cell power demand: The control unit collects data on vehicle speed (v), lithium battery SOC, and vehicle motor power consumption. and braking angle The signal is detected when the vehicle's power demand is reached. Compared with the current fuel cell stack output power The difference satisfy When the system enters the rapid load-lifting condition, it is determined that the braking angle meets the requirements. At that time, it was determined that the system had entered a rapid load reduction condition, in which... To preset the load power difference threshold, This is a preset threshold for the unloading braking angle.

[0008] Further improvements to this technical solution include the following: the rapid load increase control process in step S2 specifically includes: S21. Respond to the load increase command and control the air compressor speed. According to the formula Improvement, among which, This is the current initial speed of the air compressor; The rotational speed response coefficient; This is the difference between the vehicle's required power and the current output power of the fuel cell stack. S22, Open the rapid lifting valve to the specified opening degree. Opening degree Satisfy the formula ,in, For additional airflow that needs to be bypassed; This refers to the total airflow discharged from the intercooler; S23, Open the back pressure valve to the specified opening degree. Opening degree Satisfy the formula ,in, The target back pressure of the cathode in the fuel cell; This is the current back pressure of the cathode in the fuel cell; This is the back pressure adjustment coefficient; S24. Based on the target power of the fuel cell stack Determine the target fuel cell stack airflow requirements and target humidity requirement Calculate the opening degree of the dry air intake valve respectively. and humid air intake valve opening : ; ; in, The flow coefficient for dry air pipelines; The flow coefficient for humid air pipelines; This is a humidity mapping function; S25. Real-time monitoring of humidifier outlet pressure Adjust the opening of the humidifier's humidity control valve. Humidifier humidity control valve opening Satisfy the formula ,in, This is the pressure difference response coefficient; The humidifier inlet pressure; to make the humidifier inlet pressure Export pressure The difference satisfy Preset maximum allowable pressure difference This is the preset maximum allowable pressure difference.

[0009] Further improvements to this technical solution include the preset maximum allowable pressure difference. Based on the current output power of the fuel cell stack Make dynamic adjustments: ;in, This is the power-pressure difference correlation coefficient.

[0010] Further improvements to this technical solution include the following: The rapid load reduction control process in step S3 specifically includes: S31, responding to the vehicle's braking signal, based on the braking angle Calculate the target output power of the fuel cell and the corresponding target fuel cell stack airflow requirements Target output power of fuel cells Satisfy the formula ,in, This represents the current output power of the fuel cell stack. This is the power attenuation coefficient corresponding to the braking angle; This refers to the braking angle of the entire vehicle. S32, Control the air compressor speed According to the formula reduce; S33, Open the rapid lifting valve to the specified opening degree. Quickly raise and lower the load valve to the opening degree Satisfy the formula Excess air is bypassed directly to the exhaust pipe; S34, Open the back pressure valve to the specified opening degree. Opening degree Satisfy the formula ; S35. Based on the target fuel cell stack airflow requirement determined in step S31 Adjust the opening of the dry air intake valve and humid air intake valve opening Make it satisfy the formula This reduces the actual airflow entering the fuel cell stack. Tracking target fuel cell stack airflow requirements The tracking error satisfies , Preset flow rate error tolerance; S36. Adjust the opening of the humidifier humidity control valve. Humidifier humidity control valve opening Satisfy the formula Maintaining pressure balance between the inlet and outlet of the humidifier, thus creating a pressure difference. .

[0011] Further improvements to this technical solution include the following: the predictive control algorithm pre-stored in step S4 includes: Using a pre-trained onboard fuel cell system model, based on the vehicle speed at the current time t... lithium batteries Vehicle motor power consumption Braking angle and prediction time domain The control input within the system, and the output sequence of the prediction system in the prediction time domain. ; where the system output vector Includes the fuel cell stack inlet air pressure and flow rate; among which, , These are the fuel cell inlet air pressure and air flow rate, respectively.

[0012] Further improvements to this technical solution include the following method for optimizing the opening degree of each valve in step S4: Solving optimization problems To obtain control time domain Optimal control command sequence within : ; in, To control the command vector, Including air compressor speed Back pressure valve opening and the opening degree of the rapid lifting load valve ; To control the increment, ; To constrain the amount of violations; This is the weight matrix.

[0013] Further improvements to this technical solution include, in the cost function J of the optimization problem, the weight matrix... , This refers to the pressure tracking error weighting coefficient; For traffic tracking error weighting coefficients; weight matrix , This is the penalty coefficient for the increase in air compressor speed; This is the penalty coefficient for the back pressure valve opening increment; Penalty coefficient for rapid lifting and lowering of valve opening increment; weight matrix , The penalty coefficient for violating pressure constraints; The penalty coefficient for violating traffic constraints.

[0014] Further improvements to this technical solution include adding air compressor speed constraints to the system constraints in step S4. Valve opening constraints Stack inlet pressure constraint and fuel cell inlet flow constraints ;in, This is the minimum speed of the air compressor; This is the maximum speed of the air compressor; This is the minimum permissible pressure at the fuel cell stack inlet; This refers to the maximum permissible pressure at the fuel cell stack inlet. This is the minimum allowable flow rate at the fuel cell inlet; This represents the maximum permissible flow rate at the fuel cell inlet.

[0015] The beneficial effects of this invention are as follows: This invention adds a fast-lifting and lowering valve between the intercooler and the exhaust, which can directly bypass the excess air generated by the air compressor speed-up to the exhaust during load increase, effectively solving the problem of poor exhaust caused by the mismatch between the response speed of the air compressor and the back pressure valve, and significantly shortening the load increase time of the fuel cell from low power to high power. Under load decrease conditions, the valve can quickly discharge redundant air, and in conjunction with the precise reduction of the air compressor speed, realize the rapid drop in the stack power, and meet the dynamic response requirements of the vehicle's power system.

[0016] When the vehicle brakes, the control unit can quickly trigger the load reduction process based on the braking angle. By adjusting the opening of various valves, the output power of the fuel cell is reduced in a timely manner, and its charging rate to the power battery decreases accordingly. Combined with the charging rate of kinetic energy recovery, the total battery charging rate can be controlled within a safe range, avoiding the damage to the battery caused by the high 6C charging rate in traditional systems, significantly extending the service life of the power battery, and achieving a coordinated match between fuel cell load reduction and kinetic energy recovery.

[0017] This invention, through the coordinated adjustment of the intake dry air valve and the intake wet air valve, can precisely allocate the dry and wet air flow rates according to the target power of the fuel cell stack, meeting the stack's differentiated requirements for total air flow and humidity. At the same time, the humidifier humidity regulating valve connected in parallel with the humidifier can flexibly control the exhaust air flow rate entering the humidifier, achieving both adjustable and controllable humidification capacity of the humidifier and maintaining a stable inlet and outlet pressure difference, thus avoiding the problem of fuel cell stack efficiency fluctuations caused by uncontrollable air parameters in traditional systems.

[0018] The predictive control algorithm employed in this invention can combine multiple parameters such as vehicle speed, lithium battery SOC, and motor power consumption to predict and optimize control commands for the system output over a future period. By continuously optimizing the air compressor speed and valve openings, it can ensure that the inlet air pressure and flow rate of the fuel cell stack accurately track the target values, while also satisfying multiple constraints such as air compressor speed, valve opening, and fuel cell stack inlet parameters. This achieves multi-objective coordination in load increase / decrease response, air parameter regulation, and safe system operation, thereby improving the overall operational stability and reliability of the fuel cell cathode system.

[0019] In this invention, the maximum permissible pressure difference between the inlet and outlet of the humidifier can be dynamically adjusted according to the current output power of the fuel cell stack, avoiding the problem of insufficient adaptability of a fixed pressure difference threshold under different power conditions. At the same time, the determination of lifting and lowering load conditions can be accurately identified by combining multi-dimensional operating parameters of the whole vehicle, and the output of control commands can be adjusted in a targeted manner according to the differences in operating conditions, so that the system can adapt to different vehicle operating scenarios and has stronger adaptability and control accuracy. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic block diagram of an existing fuel cell cathode system.

[0022] Figure 2 This is a schematic block diagram of a rapid lifting and lowering system according to an embodiment of the present invention.

[0023] Figure 3 This is a schematic flowchart illustrating a method according to an embodiment of the present invention.

[0024] 111 is the air filter, 112 is the air compressor, 113 is the intercooler, 114 is the humidifier, 115 is the exhaust, 121 is the quick-lift valve, 122 is the dry air intake valve, 123 is the wet air intake valve, 124 is the humidifier humidity control valve, and 125 is the back pressure valve. Detailed Implementation

[0025] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0027] like Figure 2As shown, this invention provides a rapid load-lift system for a fuel cell cathode, including an air filter 111, an air compressor 112, an intercooler 113, a humidifier 114, an exhaust 115, a rapid load-lift valve 121, a dry air intake valve 122, a wet air intake valve 123, a humidifier humidity regulating valve 124, a back pressure valve 125, and a control unit. The air input end of the air filter 111 is connected to the outside atmosphere, and the air output end of the air filter 111 is connected to the air inlet of the fuel cell stack via the air compressor 112, the intercooler 113, and the humidifier 114 in sequence. The dry air intake valve 122 is installed on the pipeline between the air inlet of the fuel cell stack and the intercooler 113, and the wet air intake valve 123 is installed on the humidifier 114. The first air output terminal is connected to the air inlet of the fuel cell stack; the back pressure valve 125 is installed on the pipeline between the second air output terminal of the humidifier 114 and the exhaust 115 of the vehicle; the air outlet of the fuel cell stack is connected to the second air inlet of the humidifier 114; the humidifier humidity regulating valve 124 is installed on the pipeline between the air outlet of the fuel cell stack and the air inlet of the back pressure valve 125; the fast lift valve 121 is installed on the pipeline between the intercooler 113 and the exhaust 115; the control unit is electrically connected to the fast lift valve 121, the dry air intake valve 122, the wet air intake valve 123, the humidifier humidity regulating valve 124 and the back pressure valve 125 respectively, and is used to adjust the opening degree of each valve according to the power change requirements of the fuel cell.

[0028] The working principle of the rapid load increase / decrease valve 121: This valve establishes a direct bypass between the intercooler 113 and the tailpipe 115. When the fuel cell needs to rapidly increase or decrease load, the control unit adjusts its opening degree according to the power demand command: During the load increase phase, a large amount of air generated by the rapid acceleration of the air compressor 112 cannot be discharged in time through the back pressure valve 125. The valve opens to directly discharge the excess air into the tailpipe 115, avoiding poor exhaust of the fuel cell stack; During the load decrease phase, the valve opens to quickly vent the redundant air in the pipeline, and together with the deceleration of the air compressor 112, the power of the fuel cell stack drops rapidly.

[0029] The dry / wet air intake valve 123 operates as follows: Dry air intake valve 122 connects the intercooler 113 to the fuel cell stack air inlet, and wet air intake valve 123 connects the humidifier 114 to the fuel cell stack air inlet, forming a parallel path. The control unit adjusts the opening of the two valves according to the airflow and humidity requirements corresponding to the current power of the fuel cell stack, achieving dry and wet air flow distribution: when high humidity air is required, the opening of wet air intake valve 123 is increased, and the opening of dry air intake valve 122 is decreased; when a large flow of air is required, the overall opening of both valves is increased in tandem, precisely matching the air parameter requirements of the fuel cell stack reaction.

[0030] The humidifier humidity regulating valve 124 operates as follows: This valve forms a parallel structure with the humidifier 114, with one end connected to the fuel cell stack air outlet and the other end connected to the air inlet of the back pressure valve 125. The control unit adjusts its opening to control the flow rate of fuel cell stack reaction exhaust gas into the humidifier 114: when the exhaust gas intake is insufficient, the valve is closed slightly to force more exhaust gas into the humidifier 114 to replenish water and improve humidification capacity; when the pressure difference between the inlet and outlet of the humidifier 114 is too large, the valve is opened wider to divert some of the exhaust gas directly into the back pressure valve 125, maintaining a stable pressure difference between the inlet and outlet of the humidifier 114.

[0031] The back pressure valve 125 works as follows: As the main exhaust pressure control valve of the cathode system, the control unit adjusts its opening according to the back pressure requirements of the stack operation stage: when the load is increased, the back pressure valve 125 is opened synchronously to ensure that the exhaust gas after the stack reaction is smoothly discharged into the tail exhaust 115; when the load is reduced, the valve is closed appropriately to maintain the basic back pressure of the cathode system and avoid pressure fluctuations of the reaction gas in the stack.

[0032] The control unit's coordinated control method: The control unit collects data such as the fuel cell output power, vehicle braking angle, and inlet and outlet pressure of the humidifier 114 in real time, and issues opening adjustment commands to each valve according to preset logic to realize the linkage control of multiple valves, ensuring the stability of air parameters and the timeliness of response during the lifting and lowering of loads.

[0033] Taking the application scenario of fuel cells being matched with commercial vehicle power systems as an example: Rapid load increase scenario (vehicle start-up acceleration): When a commercial vehicle enters the start-up acceleration phase from idle, the vehicle controller sends a load increase command to the fuel cell, requiring the stack power to be rapidly increased from 30kW to 120kW. The control unit first instructs the air compressor 112 to rapidly increase its speed from 3000 r / min to 12000 r / min, creating a high negative pressure at the outlet of the intercooler 113, and quickly drawing in a large amount of air; Due to the delayed response of the back pressure valve 125, the control unit opens the rapid lifting load valve 121 to 50% opening, directly bypassing the excess 40% of the air at the outlet of the intercooler 113 to the tail exhaust 115 to avoid blockage of the fuel cell stack exhaust. Simultaneously open the back pressure valve to 125 to 60% to ensure the smooth discharge of fuel cell reactor tail gas; Based on the air demand corresponding to 120kW power (flow rate 180g / s, relative humidity 65%), the control unit adjusts the dry air intake valve 122 to 30% opening and the wet air intake valve 123 to 70% opening to accurately distribute the dry and wet air flow rates. The inlet and outlet pressures of humidifier 114 are monitored in real time, and the humidity regulating valve 124 of humidifier is adjusted to 20% opening to maintain the pressure difference between its inlet and outlet within the range of 0.03MPa, so as to ensure that humidifier 114 can stably output air with 65% humidity.

[0034] The entire load-up process took only 1.2 seconds, compared to 3.5 seconds for the traditional system, representing a 65.7% improvement in response speed.

[0035] Rapid unloading scenario (vehicle braking): When braking is triggered while the vehicle is in motion (braking angle 30°), the entire vehicle needs to recover kinetic energy. At this time, the fuel cell is required to rapidly unload to reduce the battery charging rate. Based on the braking angle, the control unit commands the fuel cell power to decrease from 100kW to 20kW, while simultaneously controlling the air compressor 112 speed to decrease from 10000r / min to 4000r / min, thereby reducing the amount of air intake; Open the fast lifting valve 121 to 40% opening degree to quickly discharge the redundant air in the pipeline into the tail drain 115 and accelerate the power drop of the fuel cell stack. Adjust the back pressure valve to 125% to 40% opening to maintain the basic back pressure of the cathode system; For the air requirements of 20kW power (flow rate 45g / s, relative humidity 60%), the opening of dry air intake valve 122 is adjusted to 25% and the opening of wet air intake valve 123 is adjusted to 50% to match the air parameters of low power operation. Adjust the humidity regulating valve 124 of the humidifier to 25% opening to maintain a stable pressure difference in the humidifier 114.

[0036] After the load reduction is completed, the charging rate of the fuel cell to the battery drops from 4C to 1C. Combined with the 2C charging rate from kinetic energy recovery, the total charging rate of the battery is 3C, which is within the safe charging range.

[0037] Figure 3 This is a schematic flowchart illustrating a control method according to an embodiment of the present invention. The control method is applicable to the aforementioned rapid load shedding system for fuel cell cathodes. Depending on different requirements, the order of the steps in the flowchart can be changed, and some steps can be omitted.

[0038] like Figure 3 As shown, the method includes: S1. Monitor changes in fuel cell power demand in real time to determine whether it enters a rapid load increase or rapid load decrease condition. S2. When it is determined that the rapid load increase condition has been entered, the rapid load increase control process is executed to adjust the opening of the rapid load increase valve, back pressure valve, dry air intake valve, wet air intake valve and humidifier humidity control valve. S3. When it is determined that the rapid load reduction condition has been entered, the rapid load reduction control process is executed to adjust the opening of the rapid load reduction valve, back pressure valve, dry air intake valve, wet air intake valve and humidifier humidity control valve. S4. The opening degree of each valve is optimized by using a pre-stored predictive control algorithm to ensure that the inlet air pressure and air flow of the fuel cell stack track the target value and meet the system constraints.

[0039] First, in step S1, the method for real-time monitoring of changes in fuel cell power demand includes: The control unit collects data on vehicle speed (v), lithium battery SOC, and vehicle motor power consumption. and braking angle The signal is detected when the vehicle's power demand is reached. Compared with the current fuel cell stack output power The difference satisfy When the system enters the rapid load-lifting condition, it is determined that the braking angle meets the requirements. At that time, it was determined that the system had entered a rapid load reduction condition, in which... To preset the load power difference threshold, This is a preset threshold for the unloading braking angle.

[0040] Secondly, the rapid load increase control process in step S2 specifically includes: S21. Respond to the load increase command and control the air compressor speed. According to the formula Improvement, among which, This is the current initial speed of the air compressor; The rotational speed response coefficient; The difference between the vehicle's required power and the current fuel cell output power; a high negative pressure is established at the intercooler outlet to draw in a large amount of air; S22, Open the rapid lifting valve to the specified opening degree. Opening degree Satisfy the formula ,in, For additional airflow that needs to be bypassed; This is the total airflow discharged from the intercooler; it allows some compressed air to be directly discharged into the tailpipe through the bypass pipe between the intercooler and the tailpipe to prevent excessive back pressure. S23, Open the back pressure valve to the specified opening degree. Opening degree Satisfy the formula ,in, The target back pressure of the cathode in the fuel cell; This is the current back pressure of the cathode in the fuel cell; This is the back pressure adjustment coefficient; it ensures that the gas produced after the fuel cell reactor reaction is smoothly discharged into the tail section. S24. Based on the target power of the fuel cell stack Determine the target fuel cell stack airflow requirements and target humidity requirement Calculate the opening degree of the dry air intake valve respectively. and humid air intake valve opening : ; ; in, The flow coefficient for dry air pipelines; The flow coefficient for humid air pipelines; This is a humidity mapping function; S25. Real-time monitoring of humidifier outlet pressure Adjust the opening of the humidifier's humidity control valve. Humidifier humidity control valve opening Satisfy the formula ,in, This is the pressure difference response coefficient; The humidifier inlet pressure; to make the humidifier inlet pressure Export pressure The difference satisfy Preset maximum allowable pressure difference This is the preset maximum allowable pressure difference.

[0041] Furthermore, the maximum permissible pressure difference is preset. Based on the current output power of the fuel cell stack Make dynamic adjustments: ;in, This is the power-pressure difference correlation coefficient, with a value range of [value range missing]. ;when hour, The pressure is fixed at 0.02 MPa to ensure the stability of the humidifier under low power conditions.

[0042] In addition, the rapid load reduction control process in step S3 specifically includes: S31, responding to the vehicle's braking signal, based on the braking angle Calculate the target output power of the fuel cell and the corresponding target fuel cell stack airflow requirements Target output power of fuel cells Satisfy the formula ,in, This represents the current output power of the fuel cell stack. This is the power attenuation coefficient corresponding to the braking angle; This refers to the braking angle of the entire vehicle. S32, Control the air compressor speed According to the formula Reduce, decrease the amount of air inhaled; S33, Open the rapid lifting valve to the specified opening degree. Quickly raise and lower the load valve to the opening degree Satisfy the formula Excess air is bypassed directly to the exhaust pipe; S34, Open the back pressure valve to the specified opening degree. Opening degree Satisfy the formula This ensures that the gases produced after the fuel cell reactor reaction are successfully released into the atmosphere. S35. Based on the target fuel cell stack airflow requirement determined in step S31 Adjust the opening of the dry air intake valve and humid air intake valve opening Make it satisfy the formula This reduces the actual airflow entering the fuel cell stack. Tracking target fuel cell stack airflow requirements The tracking error satisfies , Preset flow rate error tolerance; S36. Adjust the opening of the humidifier humidity control valve. Humidifier humidity control valve opening Satisfy the formula Maintaining pressure balance between the inlet and outlet of the humidifier, thus creating a pressure difference. .

[0043] During the rapid load increase phase, the compressor speed is controlled by a formula, and the negative pressure can be precisely increased according to the power difference. This allows for the rapid intake of sufficient air to match the high-power response requirements of the fuel cell stack, solving the problem of long load increase time in traditional systems. The rapid load increase valve opens according to the air flow ratio, which can promptly bypass excess compressed air, effectively balancing the response speed difference between the compressor and the back pressure valve. This avoids poor exhaust caused by excessive back pressure in the cathode system, improves the load increase response rate, and eliminates the risk of sudden pressure increases throughout the process.

[0044] The back pressure valve opening is adjusted according to the back pressure difference formula, which can synchronously match the tail gas emission requirements of the fuel cell stack, ensure the smooth discharge of gas after the reaction, maintain the stability of the cathode system pressure, and avoid the impact of pressure fluctuations on the fuel cell stack power generation efficiency.

[0045] During the load ramp-up process, the opening of the dry / wet air intake valve is calculated in conjunction with the flow rate and humidity formulas. This allows for precise allocation of the dry and wet air ratios based on the target power of the fuel cell stack, ensuring that the total flow rate and relative humidity of the incoming air perfectly match the stack reaction requirements. Compared to the drawbacks of uncontrollable air parameters in traditional systems, this control method reduces errors in the incoming air flow rate and humidity, significantly improving the stability of the stack reaction and power generation efficiency.

[0046] The humidifier's humidity regulating valve adjusts its opening according to the differential pressure formula, precisely maintaining the inlet and outlet pressure difference within a preset range. This prevents damage to the humidifier's membrane module caused by excessive pressure difference, extending the humidifier's service life. The differential pressure threshold can be dynamically adjusted according to the fuel cell power. Under low-power conditions, it is fixed at a safe differential pressure of 0.02MPa, ensuring the humidifier's operational stability at low power while increasing humidification capacity under high-power conditions by increasing the differential pressure. This achieves efficient adaptation of the humidifier across the entire power range, reducing the humidifier's failure rate.

[0047] During the rapid load reduction phase, the target power is calculated using a formula based on the braking angle, enabling precise and rapid reduction of the fuel cell stack output power. This, combined with the synchronous reduction of the air compressor speed, reduces the air supply, allowing the fuel cell stack power to drop from high power to the target power in a short time (0.5s). The rapid load reduction valve promptly bypasses redundant air, further accelerating the power reduction and significantly reducing the charging rate of the fuel cell to the power battery. With the addition of kinetic energy recovery, the total battery charging rate can be controlled below 3C, far lower than the 6C of traditional systems, avoiding damage to the battery from high-current charging and extending the cycle life of the power battery.

[0048] During load reduction, the dry / wet air intake valve adjusts its opening according to the flow demand formula, which allows the actual airflow into the stack to accurately track the target value, and the error is controlled within the preset tolerance, avoiding stack reaction imbalance caused by excessive or insufficient airflow; at the same time, the humidifier pressure difference is maintained within a safe range, ensuring the stability of the stack reaction environment throughout the load reduction process, realizing smooth switching of fuel cell power during vehicle braking, and improving the safety and comfort of the vehicle.

[0049] Finally, the pre-stored predictive control algorithms in step S4 include: Using a pre-trained onboard fuel cell system model, based on the vehicle speed at the current time t... lithium batteries Vehicle motor power consumption Braking angle and prediction time domain The control input within the system, and the output sequence of the prediction system in the prediction time domain. ; where the system output vector Includes the fuel cell stack inlet air pressure and flow rate; among which, , These are the fuel cell inlet air pressure and air flow rate, respectively.

[0050] Furthermore, the method for optimizing the opening degree of each valve in step S4 includes: Solving optimization problems To obtain control time domain Optimal control command sequence within : ; in, To control the command vector, Including air compressor speed Back pressure valve opening and the opening degree of the rapid lifting load valve ; To control the increment, ; To constrain the amount of violations; This is the weight matrix.

[0051] Furthermore, in the cost function J of the optimization problem, the weight matrix... , This is the pressure tracking error weighting coefficient, with a value range of [value range missing]. ; This is the weighting coefficient for traffic tracking error, and its value range is... Weight matrix , This is the penalty coefficient for the air compressor speed increment, with a value range of [value range missing]. ; This is the penalty coefficient for the back pressure valve opening increment, and its value range is... ; The penalty coefficient for the rapid lifting and lowering of the valve opening increment has a range of values. Weight matrix , The penalty coefficient for violating pressure constraints, with a value range of [value range missing]. ; The penalty coefficient for violating flow constraints, with a value range of [value range missing]. .

[0052] Furthermore, the system constraints in step S4 include air compressor speed constraints. Valve opening constraints Stack inlet pressure constraint and fuel cell inlet flow constraints ;in, This is the minimum speed of the air compressor; This is the maximum speed of the air compressor; This is the minimum permissible pressure at the fuel cell stack inlet; This refers to the maximum permissible pressure at the fuel cell stack inlet. This is the minimum allowable flow rate at the fuel cell inlet; This represents the maximum permissible flow rate at the fuel cell inlet.

[0053] The on-board fuel cell system model used in this invention is a hybrid mechanism and data-driven model. Its core modules include a vehicle state perception module, a cathode system dynamics module, and an output parameter prediction module. The connection relationships and functions of each module are as follows: Vehicle State Awareness Module: Serving as the input layer of the model, this module collects and preprocesses vehicle operating data at the current time t. Input data includes vehicle speed. lithium batteries Vehicle motor power consumption Braking angle This module uses a filtering algorithm to remove noise interference from the data, ensuring the accuracy of the input data; Cathode system dynamics module: As the middle layer of the model, based on the physical characteristics and fluid dynamics equations of the fuel cell cathode system, it establishes the relationship between the air compressor speed, the opening degree of each valve and the inlet air pressure and flow rate of the fuel cell stack. Its core equations include the air compression equation, the pipeline flow equation, and the fuel cell stack reaction air demand equation, which are used to map the vehicle state parameters and control input parameters to the operating state of the cathode system. Output parameter prediction module: As the output layer of the model, it outputs the predicted time domain based on the state data of the cathode system dynamics module. Internal fuel cell inlet air pressure and airflow , forming the output sequence ,in, .

[0054] Model training is divided into two stages: offline pre-training and online fine-tuning. The specific steps are as follows: Offline pre-training: Dataset Construction: Collect 100 sets of vehicle status data, control input data, and corresponding measured data of fuel cell inlet air pressure and flow rate under different vehicle operating conditions (including starting, acceleration, constant speed, braking, etc.). The time step of each set of data is 0.05s, and the data covers the air compressor speed range [3000r / min, 15000r / min] and valve opening range [0%, 100%]. Parameter initialization: Set the adiabatic index of the air compression equation in the cathode system dynamics module to 1.4 and the pipeline resistance coefficient to 0.02, and initialize the initial values ​​of each weight matrix; Model training: The gradient descent method is used to train the model. The mean square error between the predicted and measured values ​​of the inlet air pressure and flow rate of the fuel cell stack is used as the loss function. The training is iterated until the loss function value is lower than 0.01, and then the pre-trained on-board fuel cell system model is obtained.

[0055] Online fine-tuning: After the pre-trained model is deployed to the vehicle controller, the model parameters are fine-tuned every 100 hours of operation using the 10 most recently collected sets of operating condition data to ensure the prediction accuracy of the model throughout the entire life cycle of the vehicle.

[0056] The control unit extracts only the optimal control command sequence. The first control command u(t) is applied to the actual fuel cell cathode system, and the control cycle T is set to 0.05s. In the next control cycle, new vehicle status data and system output data are collected, the model input is updated, and the "prediction-optimization-execution" process is repeated to achieve closed-loop rolling control.

[0057] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A rapid loading and unloading system for a fuel cell cathode, characterized in that, Includes an air filter (111), an air compressor (112), an intercooler (113), a humidifier (114), an exhaust (115), a quick-lift valve (121), a dry air intake valve (122), a wet air intake valve (123), a humidifier humidity control valve (124), a back pressure valve (125), and a control unit; The air inlet of the air filter (111) is connected to the outside atmosphere, and the air outlet of the air filter (111) is connected to the air inlet of the fuel cell stack via the air compressor (112), the intercooler (113) and the humidifier (114) in sequence. The dry air intake valve (122) is installed on the pipeline between the air inlet of the fuel cell stack and the intercooler (113), and the wet air intake valve (123) is installed on the pipeline between the first air outlet of the humidifier (114) and the air inlet of the fuel cell stack. The back pressure valve (125) is installed on the pipeline between the second air outlet of the humidifier (114) and the exhaust pipe (115) of the vehicle. The air outlet of the fuel cell stack is connected to the second air inlet of the humidifier (114), and the humidity regulating valve (124) of the humidifier is installed on the pipeline between the air outlet of the fuel cell stack and the air inlet of the back pressure valve (125). The fast lift valve (121) is installed on the pipeline between the intercooler (113) and the exhaust pipe (115). The control unit is electrically connected to the fast lifting load valve (121), dry air intake valve (122), wet air intake valve (123), humidifier humidity regulating valve (124) and back pressure valve (125) respectively, and is used to adjust the opening of each valve according to the power change requirements of the fuel cell.

2. A control method applicable to the rapid loading and unloading system of the fuel cell cathode as described in claim 1, characterized in that, include: S1. Monitor changes in fuel cell power demand in real time to determine whether it enters a rapid load increase or rapid load decrease condition. S2. When it is determined that the rapid load increase condition has been entered, the rapid load increase control process is executed to adjust the opening of the rapid load increase valve, back pressure valve, dry air intake valve, wet air intake valve and humidifier humidity control valve. S3. When it is determined that the rapid load reduction condition has been entered, the rapid load reduction control process is executed to adjust the opening of the rapid load reduction valve, back pressure valve, dry air intake valve, wet air intake valve and humidifier humidity control valve. S4. The opening degree of each valve is optimized by using a pre-stored predictive control algorithm to ensure that the inlet air pressure and air flow of the fuel cell stack track the target value and meet the system constraints.

3. The control method according to claim 2, characterized in that, In step S1, the method for real-time monitoring of changes in fuel cell power demand includes: The control unit collects data on vehicle speed (v), lithium battery SOC, and vehicle motor power consumption. and braking angle The signal is received when the vehicle's power demand is detected. Compared with the current fuel cell stack output power The difference satisfy When the system enters the rapid load-lifting condition, it is determined that the braking angle meets the requirements. At that time, it was determined that the system had entered a rapid load reduction condition, in which... To preset the load power difference threshold, This is a preset threshold for the unloading braking angle.

4. The control method according to claim 3, characterized in that, The rapid load increase control process in step S2 specifically includes: S21. Respond to the load increase command and control the air compressor speed. According to the formula Improvement, among which, This is the current initial speed of the air compressor; The rotational speed response coefficient; This is the difference between the vehicle's required power and the current output power of the fuel cell stack. S22, Open the rapid lifting valve to the specified opening degree. Opening degree Satisfy the formula ,in, For additional airflow that needs to be bypassed; This refers to the total airflow discharged from the intercooler; S23, Open the back pressure valve to the specified opening degree. Opening degree Satisfy the formula ,in, The target back pressure of the cathode in the fuel cell; This is the current back pressure of the cathode in the fuel cell; This is the back pressure adjustment coefficient; S24. Based on the target power of the fuel cell stack Determine the target fuel cell stack airflow requirements and target humidity requirement Calculate the opening degree of the dry air intake valve respectively. and humid air intake valve opening : ； ； in, The flow coefficient for dry air pipelines; The flow coefficient for humid air pipelines; This is a humidity mapping function; S25. Real-time monitoring of humidifier outlet pressure Adjust the opening of the humidifier's humidity control valve. Humidifier humidity control valve opening Satisfy the formula ,in, This is the pressure difference response coefficient; The humidifier inlet pressure; to make the humidifier inlet pressure Export pressure The difference satisfy Preset maximum allowable pressure difference This is the preset maximum allowable pressure difference.

5. The control method according to claim 4, characterized in that, Preset maximum allowable pressure difference Based on the current output power of the fuel cell stack Make dynamic adjustments: ;in, This is the power-pressure difference correlation coefficient.

6. The control method according to claim 4, characterized in that, The rapid load reduction control process in step S3 specifically includes: S31, responding to the vehicle's braking signal, based on the braking angle Calculate the target output power of the fuel cell and the corresponding target fuel cell stack airflow requirements Target output power of fuel cells Satisfy the formula ,in, This represents the current output power of the fuel cell stack. This is the power attenuation coefficient corresponding to the braking angle; This refers to the braking angle of the entire vehicle. S32, Control the air compressor speed According to the formula reduce; S33, Open the rapid lifting valve to the specified opening degree. Quickly raise and lower the load valve to the opening degree Satisfy the formula Excess air is bypassed directly to the exhaust pipe; S34, Open the back pressure valve to the specified opening degree. Opening degree Satisfy the formula ; S35. Based on the target fuel cell stack airflow requirement determined in step S31 Adjust the opening of the dry air intake valve and humid air intake valve opening Make it satisfy the formula This reduces the actual airflow entering the fuel cell stack. Tracking target fuel cell stack airflow requirements The tracking error satisfies , Preset flow rate error tolerance; S36. Adjust the opening of the humidifier humidity control valve. Humidifier humidity control valve opening Satisfy the formula Maintaining pressure balance between the inlet and outlet of the humidifier, thus creating a pressure difference. .

7. The control method according to claim 3, characterized in that, The pre-stored predictive control algorithms in step S4 include: Using a pre-trained onboard fuel cell system model, based on the vehicle speed at the current time t... lithium batteries Vehicle motor power consumption Braking angle and prediction time domain The control input within the system, and the output sequence of the prediction system in the prediction time domain. ; where the system output vector Includes the fuel cell stack inlet air pressure and flow rate; among which, , These are the fuel cell inlet air pressure and air flow rate, respectively.

8. The control method according to claim 7, characterized in that, The method for optimizing the opening degree of each valve in step S4 includes: Solving optimization problems To obtain control time domain Optimal control command sequence within : ； in, To control the command vector, Including air compressor speed Back pressure valve opening and the opening degree of the rapid lifting load valve ; To control the increment, ; To constrain the amount of violations; This is the weight matrix.

9. The control method according to claim 8, characterized in that, In the cost function J of the optimization problem, the weight matrix , This refers to the pressure tracking error weighting coefficient; For traffic tracking error weighting coefficients; weight matrix , This is the penalty coefficient for the increase in air compressor speed; This is the penalty coefficient for the back pressure valve opening increment; Penalty coefficient for rapid lifting and lowering of valve opening increment; weight matrix , The penalty coefficient for violating pressure constraints; The penalty coefficient for violating traffic constraints.

10. The control method according to claim 8, characterized in that, The system constraints in step S4 include the air compressor speed constraint. Valve opening constraints Stack inlet pressure constraint and fuel cell inlet flow constraints ;in, This is the minimum speed of the air compressor; This is the maximum speed of the air compressor; This is the minimum permissible pressure at the fuel cell stack inlet; This refers to the maximum permissible pressure at the fuel cell stack inlet. This is the minimum allowable flow rate at the fuel cell inlet; This represents the maximum permissible flow rate at the fuel cell inlet.

Images