Fuel cell power generation system and control method thereof

Abstract

The application relates to a fuel cell power generation system and a control method thereof. A bypass channel is constructed, a first end of the bypass channel is connected between an air compressor outlet end and an air inlet valve, a second end of the bypass channel is connected between an air outlet valve and a turbine end inlet end, and the channel is controlled to be opened during a system starting stage and / or a system shutdown stage, a circulating air flow is formed from the air compressor to the air compressor through the bypass channel, and the air compressor turbine end is directly purged. During the starting stage, the circulating air flow is established in advance, preheating and drying of the turbine end are realized, during the shutdown stage, residual moisture in the turbine end and pipelines is forcedly removed, water vapor penetration and low-temperature icing caused by disappearance of a pressure difference after shutdown are avoided, and thus insulation resistance of the system is remarkably improved, insulation failure is prevented, and the problem of insulation performance reduction caused by residual moisture in the air compressor turbine end is solved from the root by the simple bypass channel. No additional complex external air source or drying device is needed, and the application has compactness and high reliability.

Description

Technical Field

[0001] This application relates to the field of green and low-carbon industries, and in particular to a fuel cell power generation system and its control method. Background Technology

[0002] Fuel cell systems have attracted widespread attention due to their high efficiency and cleanliness, particularly demonstrating enormous application potential in transportation and stationary power generation. However, optimizing the design of fuel cell systems is crucial for further improving their performance and economic viability.

[0003] In a fuel cell system, the air compressor is the core component of the air supply subsystem. The main function of the air compressor is to compress outside air to the pressure required by the fuel cell stack and provide sufficient flow to ensure adequate oxygen supply to the cathode side of the fuel cell stack for the electrochemical reaction. Simultaneously, it must also maintain the hydrothermal balance within the fuel cell stack.

[0004] A turbocharged air compressor is an air compressor with a turbine expansion end (referred to in the industry as the "turbine end"). This type of air compressor typically arranges the compressor wheel, motor, and turbine expansion wheel coaxially. The most important advantage of a turbocharged air compressor is its energy recovery capability. The exhaust gas from the fuel cell cathode still contains a certain pressure and temperature. Introducing this exhaust gas into the turbine end for expansion and work recovery recovers kinetic energy. This kinetic energy can then assist in driving the compressor wheel's rotation, thereby reducing the power required by the motor and lowering the overall power consumption of the turbocharged air compressor.

[0005] Because the air reaction on the cathode side of the fuel cell stack produces a large amount of liquid water, this water is discharged with the gas and enters the turbine end of the turbocharger. If this liquid water problem is not addressed, the turbine end will freeze, causing the mechanical structure to malfunction or other mechanical failures.

[0006] Some designers have considered addressing this issue by improving the internal structure of turbocharged air compressors. However, the development of sealing structures for traditional turbocharged air compressors is still in its early stages, and manufacturers have not yet recognized this problem. They generally use a comb-tooth structure for sealing, and its sealing effectiveness depends on the pressure difference between the compressor end and the turbine end. During the operation of a turbocharged air compressor, due to oxygen consumption as air passes through the fuel cell stack and the stack's own resistance, the pressure at the compressor end is higher than that at the turbine end, ensuring that moisture from the turbine end does not leak into the compressor end or the motor cavity. However, when the turbocharged air compressor stops operating, the pressure difference disappears, and if moisture remains at the turbine end, it may leak into the compressor end or the motor cavity.

[0007] Some designers have attempted to add a gas-liquid separator between the fuel cell stack outlet and the turbine end to reduce the generation of liquid water at the turbine end. Although field tests show that this method can appropriately reduce the generation of liquid water, it cannot completely eliminate it.

[0008] Alternatively, some designers mount turbocharged air compressors above the fuel cell stack, using gravity to prevent liquid water from flowing into the compressor. However, this design increases the risk of generated water flowing back into the stack.

[0009] In summary, traditional fuel cell systems have not solved the problem of liquid water entering the turbine end of the turbocharged air compressor during operation, which could lead to potential malfunctions. Summary of the Invention

[0010] Therefore, it is necessary to provide a fuel cell power generation system and its control method to address the problem that traditional fuel cell systems have not solved, which is that liquid water may enter the turbine end of the turbocharged air compressor during operation, leading to potential malfunctions.

[0011] On one hand, this application provides a fuel cell power generation system, including: The fuel cell stack has an air inlet and an air outlet. An air compressor has an air compressor inlet end for receiving air and an air compressor outlet end for outputting compressed air; the air compressor also includes a turbine end inlet end and a turbine end outlet end. An air inlet valve is connected between the air compressor outlet and the fuel cell air inlet. An air outlet valve is connected between the fuel cell stack air outlet and the turbine end inlet. A bypass channel includes a first bypass channel end and a second bypass channel end. The first bypass channel end is connected to the air line between the air compressor outlet end and the air inlet valve, and the second bypass channel end is connected to the air line between the air outlet valve and the turbine inlet end. When the fuel cell power generation system is in the start-up phase and / or in the shutdown phase, the bypass channel is controlled to open to establish a circulating airflow from the air compressor output and then back to the air compressor via the bypass channel. This circulating airflow is used to purge the air compressor turbine end of the air compressor.

[0012] This application relates to a fuel cell power generation system. A bypass channel is constructed, with its first end connected between the air compressor outlet and the air inlet valve, and its second end connected between the air outlet valve and the turbine inlet. This channel is opened during system startup and / or shutdown, forming a circulating airflow from the air compressor back to the air compressor via the bypass channel, directly purging the air compressor turbine. During startup, the circulating airflow is established in advance, preheating and drying the air compressor turbine. During shutdown, the circulating airflow forcibly removes residual moisture from the air compressor turbine and pipelines, preventing water vapor infiltration and low-temperature icing caused by the loss of pressure differential after shutdown, thereby significantly improving the system's insulation resistance and preventing insulation failure. Based on this structure, this application fundamentally solves the problem of decreased insulation performance caused by residual moisture at the air compressor turbine in existing technologies with a simple bypass channel, eliminating the need for complex external air sources or drying devices, and combining structural compactness with high reliability.

[0013] On the other hand, this application provides a control method for a fuel cell power generation system, applied to the aforementioned fuel cell power generation system, the control method for the fuel cell power generation system comprising: During the power-on phase, the first control strategy is executed; During the shutdown phase, the second control strategy is executed; The execution of the first control strategy during the power-on phase includes: In response to receiving a start command, the bypass channel is opened and the air compressor is started to establish a circulating airflow from the air compressor outlet end through the bypass channel to the turbine inlet end; After the circulating airflow is established, the hydrogen supply and circulation unit are controlled to supply hydrogen to the anode of the fuel cell stack; The air inlet valve is opened to establish a main airflow from the air compressor outlet end through the cathode of the fuel cell stack to the turbine inlet end; During the shutdown phase, the execution of the second control strategy includes: In response to receiving a shutdown command, the air inlet valve and the air outlet valve are closed; The bypass channel is kept open, and the air compressor is controlled to continue running for a predetermined time to purge the air compressor turbine end through the circulating air flow.

[0014] This application relates to a control method for a fuel cell power generation system. The control method is divided into a first control strategy for the start-up phase and a second control strategy for the shutdown phase. During start-up, the bypass channel is first opened to establish circulating air flow, then hydrogen is supplied, and finally the main circuit is opened. During shutdown, the main circuit valve is first closed, then the bypass channel is maintained, and the air compressor continues to run for a predetermined time. The first control strategy achieves early dilution of the exhaust hydrogen at the moment of start-up and accelerates the establishment of the open-circuit voltage; the second control strategy ensures continuous purging of the turbine end after shutdown. Based on the above timing control, this application provides a control method with software-level strategy optimization and deep collaboration with the hardware bypass structure, achieving a dual improvement in system insulation performance and start-up response speed at extremely low cost. Attached Figure Description

[0015] Figure 1 This is a structural block diagram of a fuel cell power generation system provided in one embodiment of this application.

[0016] Figure 2 This is a schematic diagram of a fuel cell power generation system provided in one embodiment of this application.

[0017] Figure 3 This is a flowchart illustrating a control method for a fuel cell power generation system according to an embodiment of this application.

[0018] Figure 4 The flowchart illustrates the execution of a first control strategy during the startup phase of a control method for a fuel cell power generation system provided in an embodiment of this application.

[0019] Figure 5 The flowchart illustrates the execution of a second control strategy during the shutdown phase in a control method for a fuel cell power generation system provided in an embodiment of this application.

[0020] Figure 6 A comparison chart showing the tail gas hydrogen concentration and drain valve opening / closing status after using the conventional method and the method provided in this application.

[0021] Figure 7 A comparison chart showing the air compressor speed, air inlet valve opening, air outlet valve opening, and bypass valve opening after using the conventional solution and the solution provided in this application.

[0022] Figure 8 A comparison chart of airflow rates after using the conventional method and the method provided in this application.

[0023] Figure 9 A comparison chart of stack current and minimum unit voltage during the startup phase, using both conventional and the solutions provided in this application.

[0024] Figure 10A comparison chart showing the air compressor speed, air inlet valve opening, and bypass valve opening during the start-up phase, after using the conventional solution and the solution provided in this application.

[0025] Figure 11 A comparison chart of air inlet pressure during startup using the conventional approach and the approach provided in this application.

[0026] Figure 12 The diagram shows the parameters of the fuel cell stack current and minimum individual cell voltage during the shutdown phase after using the solution provided in this application.

[0027] Figure 13 The parameter diagram for the air compressor speed, air inlet valve opening and bypass valve opening during the shutdown phase after using the solution provided in this application.

[0028] Figure 14 A parameter diagram of air inlet pressure during the shutdown phase after using the scheme provided in this application.

[0029] Figure label: 10 - Hydrogen supply and circulation unit; 100 - Hydrogen system; 101 - Hydrogen system controller; 102 - Shut-off valve; 103-First proportional valve; 104-Second proportional valve; 105-Ejector; 106-Pressure relief valve; 107 - First sensor; 20 - Hydrogen safety emission unit; 210 - Liquid-water separator; 211 - First interface of the liquid-water separator; 212 - Second interface of the liquid-water separator; 213 - Third interface of liquid-water separator; 220 - Second sensor; 230 - Drain valve; 231 - Drain valve inlet; 232 - Drain valve outlet; 240 - One-way pressure relief line; 250 - Hydrogen discharge line; 30 - Air supply and bypass unit; 301 - Chemical filter; 302 - Air mass flow meter; 303 - Air compressor; 303a - Air compressor inlet end; 303b - Air compressor outlet end; 303c - Turbine end inlet; 303d - Turbine end outlet; 303e - Air compressor end; 303f - Air compressor turbine end; 304 - Intercooler; 305 - Air inlet valve; 306 - Third sensor; 307 - Fourth sensor; 308 - Air outlet valve; 309 - Silencer; 310 - Bypass channel; 311 - First end of bypass channel; 312 - Second end of bypass channel; 313 - Bypass valve; 320 - Fuel cell stack purging line; 330 - Check valve; 40 - Hydrothermal management unit; 401 - Fifth sensor; 402 Water pump; 403 Particulate filter; 404 Cooling fan; 405 Water supply tank; 406 - PTC liquid heating plate; 407 - Ion filter; 408 - Cooling water three-way valve; 409 - Sixth sensor; 50 - Fuel cell stack and reaction unit; 500 - Fuel cell stack; 501 - Fuel cell stack positive electrode; 502 - Negative electrode of fuel cell stack; 510 - Hydrogen inlet of fuel cell stack; 520 - Hydrogen outlet of fuel cell stack; 530 - Fuel cell air inlet; 540 - Fuel cell air outlet; 550 - Fuel cell coolant inlet; 560 - Stack coolant outlet; 571 - Individual cell voltage monitoring module; 572 - Seventh sensor; 60 - Electrical and control unit; 610 - Air compressor drive; 611 - Fuel cell controller; 612 - DC-DC converter; 613 - Air pump controller; 70 - Whole vehicle. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0031] This application relates to devices that directly convert chemical energy into electrical energy. Optionally, this application relates to hydrogen fuel cell equipment. Optionally, this application relates to new energy vehicle devices.

[0032] This application provides a fuel cell power generation system. For the sake of brevity, the fuel cell power generation system will be referred to as the "system" below. Whenever the term "system" appears, it refers to the fuel cell power generation system, and will not be elaborated further. Optionally, the fuel cell power generation system can be a fuel cell engine system. The fuel cell engine system can be installed in new energy vehicles to achieve green, low-carbon, and clean travel.

[0033] like Figure 1 As shown, in one embodiment of this application, the fuel cell power generation system includes a fuel cell stack 500, an air compressor 303, an air inlet valve 305, an air outlet valve 308, and a bypass channel 310.

[0034] The fuel cell stack 500 has a fuel cell air inlet 530 and a fuel cell air outlet 540. The air compressor 303 has an air compressor inlet end 303a for receiving air and an air compressor outlet end 303b for outputting compressed air. The air compressor 303 also includes a turbine end inlet end 303c and a turbine end outlet end 303d. An air inlet valve 305 is connected between the air compressor outlet end 303b and the fuel cell air inlet 530. An air outlet valve 308 is connected between the fuel cell air outlet 540 and the turbine end inlet end 303c.

[0035] The bypass channel 310 includes a first bypass channel end 311 and a second bypass channel end 312. The first bypass channel end 311 is connected to the air path between the air compressor outlet end 303b and the air inlet valve 305. The second bypass channel end 312 is connected to the air path between the air outlet valve 308 and the turbine end inlet end 303c.

[0036] When the fuel cell power generation system is in the start-up phase and / or in the shutdown phase, the bypass channel 310 is controlled to open to establish a circulating airflow from the air compressor 303 and back to the air compressor 303 via the bypass channel 310. This circulating airflow is used to purge the air compressor turbine end 303f of the air compressor 303.

[0037] Specifically, the fuel cell stack 500 is a core power generation component composed of multiple individual cells connected in series. Each individual cell includes a membrane electrode assembly (MEA) and a bipolar plate. The fuel cell stack air inlet 530 refers to the physical interface through which air enters the cathode side of the fuel cell stack 500, and is typically located on the end plate of the fuel cell stack 500. The fuel cell stack air outlet 540 refers to the physical interface through which the waste gas after the reaction is discharged from the fuel cell stack 500. The waste gas may contain residual oxygen, generated water vapor, and liquid water.

[0038] The air compressor 303, or air compressor, has the core function of compressing ambient air to the pressure required by the fuel cell stack 500, for example, 2.5 to 3.0 times the absolute pressure. The air compressor 303 includes two ends: a compressor inlet end 303e and a compressor turbine end 303f. The compressor inlet end 303e has an inlet end 303a for receiving air and an outlet end 303b for outputting compressed air. The compressor turbine end 303f includes a turbine inlet end 303c and a turbine outlet end 303d. The compressor inlet end 303a can be connected to air purification and silencing equipment to filter impurities and reduce intake noise. The compressor outlet end 303b is connected to downstream components such as the intercooler 304.

[0039] Optionally, the fuel cell power generation system also includes an intercooler 304, which is used to cool the compressed air to ensure that the intake temperature of the air entering the fuel cell stack 500 is sufficiently suitable. The intercooler 304 can be located between the air compressor outlet 303b and the fuel cell stack air inlet 530. Specifically, the intercooler 304 can be located between the air inlet valve 305 and the air compressor outlet 303b, such as... Figure 2 As shown.

[0040] The air inlet valve 305 can be an electric butterfly valve or a solenoid valve, which opens or closes under the command of the control unit to control whether compressed air enters the fuel cell stack 500. The control unit can be the fuel cell controller 611 in the fuel cell power generation system. The fuel cell controller 611 is called the Fuel Cell Control Unit, abbreviated as FCU. As the main control unit of the fuel cell power generation system, the FCU ensures the safe and reliable operation of the fuel cell power generation system.

[0041] The air outlet valve 308 is also an electrically controlled valve, and its opening degree is used to adjust the pressure on the cathode side of the fuel cell stack 500 to match the reaction requirements under different operating conditions.

[0042] The bypass channel 310 is constructed of a pressure-resistant pipe. In a specific example, the first end 311 of the bypass channel is connected to the pipe between the air compressor outlet end 303b and the air inlet valve 305. Specifically, the first end 311 of the bypass channel can be located between the intercooler 304 and the air inlet valve 305, allowing air to be drawn from between the intercooler 304 and the air inlet valve 305. The second end 312 of the bypass channel is connected to the pipe between the air outlet valve 308 and the turbine inlet end 303c.

[0043] When the fuel cell power generation system is in the start-up phase and / or in the shutdown phase, the bypass channel 310 is controlled to open to establish a circulating airflow from the air compressor 303 and back to the air compressor 303 via the bypass channel 310. In essence, this circulating airflow is output from the air compressor outlet 303b, passes through the bypass valve 313, and then returns to the turbine inlet 303c.

[0044] In this embodiment, a bypass channel 310 is constructed, with its first end connected between the air compressor outlet end 303b and the air inlet valve 305, and its second end connected between the air outlet valve 308 and the turbine inlet end 303c. This channel is opened during system startup and / or shutdown, forming a circulating airflow from the air compressor 303 back to the air compressor 303 via the bypass channel 310, directly purging the air compressor turbine end 303f. During startup, the circulating airflow is established in advance to preheat and dry the air compressor turbine end 303f. During shutdown, the circulating airflow forcibly removes residual moisture from the air compressor turbine end 303f and the pipeline, preventing water vapor infiltration and low-temperature icing caused by the disappearance of pressure difference after shutdown. This significantly improves the system insulation resistance and prevents insulation failures. Based on the above structure, this application solves the problem of reduced insulation performance caused by residual moisture at the turbine end of the air compressor 303f in the prior art from the root by using a simple bypass channel. It does not require an additional complex external air source or drying device, and has both compact structure and high reliability.

[0045] In one embodiment of this application, such as Figure 2 As shown, the fuel cell power generation system also includes a bypass valve 313. The bypass valve 313 is disposed on the bypass channel 310. The bypass valve 313 is used to control the opening and closing of the bypass channel 310.

[0046] Specifically, the bypass valve 313 is an electrically controlled on / off valve, which can be a solenoid shut-off valve, an electric ball valve, or a three-way valve. The bypass valve 313 is installed in series on the bypass channel 310. During normal operation, the bypass valve 313 remains closed to block the bypass channel 310, ensuring that all compressed air enters the fuel cell stack 500 for reaction via the air inlet valve 305. When start-up or shutdown purging is required, the fuel cell controller 611 sends an opening signal to the bypass valve 313, such as a 24V DC or PWM signal, causing the bypass valve 313 to open and the bypass channel 310 to be established. The timing of the opening and closing of the bypass valve 313 is precisely determined by the control strategy. For example, during start-up, the bypass valve 313 opens simultaneously with or before the air compressor 303 starts; during shutdown, the bypass valve 313 opens immediately after the air inlet valve 305 and the air outlet valve 308 are closed. The introduction of bypass valve 313 allows the system to flexibly enable or disable the bypass function without changing the existing main gas path structure, facilitating modular design and fault isolation.

[0047] In this embodiment, by setting a bypass valve 313 on the bypass channel 310, precise electronic control of the opening and closing of the bypass channel 310 is achieved. As a reliable actuator, the bypass valve 313 enables the system controller to automatically open or close the circulating airflow according to preset timings (start-up phase and / or shutdown phase) without manual intervention, thereby improving the automation and consistency of the purging control.

[0048] In one embodiment of this application, such as Figure 2 As shown, the fuel cell stack 500 also includes a fuel cell hydrogen outlet 520. The fuel cell hydrogen outlet 520 is connected to a liquid-water separator 210. The fuel cell power generation system also includes a drain valve 230.

[0049] The drain valve 230 includes a drain valve inlet 231 and a drain valve outlet 232. The drain valve inlet 231 is connected to the liquid-water separator 210. The drain valve outlet 232 is connected to the turbine end outlet 303d.

[0050] The circulating airflow is also used to dilute the hydrogen-containing waste gas discharged from the drain valve 230 when the fuel cell power generation system is in the start-up phase.

[0051] Specifically, the hydrogen outlet 520 of the fuel cell stack is the outlet for unreacted hydrogen gas, as well as generated water vapor and liquid water, on the anode side of the fuel cell stack 500. It can be easily understood that the anode side of the fuel cell stack 500 refers to the part where hydrogen enters and exits, while the cathode side refers to the part where air enters and exits.

[0052] The hydrogen outlet 520 of the fuel cell stack is connected to the liquid-water separator 210. The liquid-water separator 210 may be equipped with a spiral separation mesh or impact plate to separate the liquid water from the material discharged from the hydrogen outlet 520. The separated liquid water accumulates at the bottom of the liquid-water separator 210. The drain valve 230 can be a normally closed solenoid valve, with its inlet 231 connected to the third port 213 of the liquid-water separator 210. The liquid-water separator 210 has three ports. The third port 213 of the liquid-water separator 210 is the bottom drain outlet. The second port 212 of the liquid-water separator 210 is connected to the hydrogen outlet 520 of the fuel cell stack. The drain valve outlet 232 is connected to the turbine end outlet 303d, ensuring that the discharged liquid water and a small amount of accompanying hydrogen-containing waste gas are mixed with the cathode waste gas airflow discharged from the turbine end 303f of the air compressor via the turbine end outlet 303d before being discharged.

[0053] The circulating airflow mentioned in this application refers to the airflow that starts from the air compressor outlet 303b, passes through the intercooler 304, passes through point X, passes through the bypass valve 313, passes through point Y, and flows to the turbine inlet 303c. This will not be explained again below.

[0054] The main airflow mentioned in this application refers to the airflow that originates from the air compressor outlet 303b, passes through the intercooler 304, passes point X, passes through the air inlet valve 305, enters the fuel cell stack 500 through the fuel cell stack air inlet 530, participates in the chemical reaction within the fuel cell stack 500, flows out through the fuel cell stack air outlet 540, passes through the air outlet valve 308, passes through point Y, flows to the turbine end inlet 303c, and finally exits from the silencer 309. This will not be explained again below.

[0055] The exhaust flow mentioned in this application refers to the gas flow that starts from the liquid-water separator 210, passes through the drain valve 230, passes through point J, passes through point W, and is finally discharged into the atmosphere through the silencer 309.

[0056] During startup, once the bypass channel 310 has established a circulating airflow, the hydrogen supply and circulation unit 10 supplies hydrogen to the anode of the fuel cell stack 500, and the anode side operates. Simultaneously, the air inlet valve 305 can be opened to establish a main airflow from the air compressor outlet 303b through the cathode of the fuel cell stack 500 to the turbine inlet 303c; at this time, the cathode side operates. After both the anode and cathode sides are operating normally, the main airflow is established. Once the main airflow is established, the control system controls the drain valve 230 to open periodically or continuously. At this time, the condensate accumulated inside the liquid-water separator 210 and the hydrogen in the anode exhaust gas are discharged to the turbine outlet 303d through the drain valve 230 (i.e., the tail exhaust flow). Since the air compressor 303 is currently bypassing the main airflow through the bypass channel 310, the circulating airflow helps increase the flow rate of the main airflow, resulting in a higher flow velocity and turbulence, allowing it to mix with the gas discharged through the drain valve 230 to form a composite gas.

[0057] Therefore, the compound gas discharged from the muffler 309 consists of three streams: the exhaust flow, the main air flow, and the circulating air flow.

[0058] Since the main airflow will not contain hydrogen unless the airtightness of fuel cell 500 is severely compromised, it can quickly dilute the hydrogen concentration in the gas discharged from drain valve 230 to below the safe limit for hydrogen concentration, for example, 4%. This concentration of discharged hydrogen is the tail gas hydrogen concentration. The combined gas eventually passes through silencer 309 and then is discharged into the atmosphere through the exhaust port. For example, in the experiment, the tail gas hydrogen concentration exceeded 10% when the bypass channel 310 was not open, but dropped to below 6% after the bypass circulation was opened.

[0059] During the hydrogen venting process at startup, the main airflow is newly established and the flow rate is small. Therefore, the circulating airflow plays a major role in the first hydrogen venting process, effectively helping to dilute the hydrogen concentration in the exhaust gas.

[0060] In this embodiment, by connecting the drain valve inlet 231 to the liquid-water separator 210 on the hydrogen outlet 520 side of the fuel cell stack, and connecting the drain valve outlet 232 to the turbine end inlet 303c, the safe discharge of hydrogen-containing waste gas from the anode side of the fuel cell stack 500 is achieved. Simultaneously, the circulating airflow established by the bypass channel 310 dilutes the hydrogen-containing waste gas during startup, effectively reducing the hydrogen concentration in the gas emitted from the silencer 309 to below safe levels, thus avoiding the risk of combustion and explosion caused by hydrogen accumulation.

[0061] In one embodiment of this application, the air compressor 303 is a turbine air compressor with a turbine kinetic energy recovery device.

[0062] Specifically, a turbine air compressor with a turbine kinetic energy recovery device is called a scroll air compressor. This type of compressor integrates a compressor impeller and a turbine impeller, which are mechanically connected coaxially. During normal operation, the high-temperature, high-pressure exhaust gas discharged from the fuel cell stack air outlet 540 has a temperature of approximately 70 to 90 degrees Celsius and a pressure higher than atmospheric pressure. After being delivered to the compressor turbine end 303f, this exhaust gas drives the turbine impeller, thereby recovering some energy to assist in driving the compressor impeller and reducing the power consumption of the motor within the compressor 303. However, this high-temperature, high-pressure exhaust gas contains a large amount of water vapor and liquid water. When this exhaust gas passes through the compressor turbine end 303f, some of the water vapor condenses and adheres to the inner wall of the compressor casing and the turbine blades. When the fuel cell power generation system is shut down, the pressure difference across the sealed structure of the compressor 303 disappears, and the remaining moisture may seep into the motor chamber along the compressor turbine end 303f. This application utilizes the circulating airflow established by the bypass channel 310 to continuously purge the internal flow channel of the air compressor turbine end 303f after shutdown. This can blow liquid water towards the turbine end outlet end 303d of the air compressor turbine end 303f or cause it to evaporate, thereby preventing moisture from migrating into the motor cavity. The solution of this application is particularly suitable for the special structure of scroll air compressors, solving the problem of decreased insulation resistance that is usually not present in existing ordinary air compressors.

[0063] In this embodiment, by defining the air compressor 303 as a scroll air compressor with a turbine kinetic energy recovery device, the most applicable technical scenario for this application is clearly defined. This type of air compressor, due to the presence of water vapor in the exhaust gas at the turbine end 303f, is precisely the type prone to insulation resistance degradation. This application retains the energy-saving advantages of kinetic energy recovery in scroll air compressors while overcoming their inherent water accumulation defects, achieving a balance between energy efficiency and reliability.

[0064] In one embodiment of this application, the drain valve 230 is a solenoid valve with heating function.

[0065] Specifically, a heating element (not shown in the figure) is integrated inside or outside the valve body of the drain valve 230. This heating element can be a positive temperature coefficient thermistor heating element or a resistance wire heater. When the ambient temperature is lower than a preset temperature threshold, the fuel cell controller 611 activates the heating element before or simultaneously with opening the drain valve 230 to preheat the inside of the valve body, melting any ice crystals or frozen condensate. The preset temperature threshold can be 0 degrees Celsius. The operating voltage of the heating element can be 12V or 24V, the power can be between 5 watts and 20 watts, and the heating time can be between 5 seconds and 20 seconds. Once the valve body temperature of the drain valve 230 reaches the preset temperature threshold, the fuel cell controller 611 sends an opening signal to drive the electromagnet inside the drain valve 230 to engage, opening the valve for drainage. Furthermore, after the system shuts down, the heating element can remain powered for a period of time to ensure that residual moisture in the drain valve 230 is evaporated or discharged, preventing the drain valve 230 from becoming stuck in the open or closed state due to icing.

[0066] In this embodiment, by setting the drain valve 230 as a solenoid valve with heating function, the valve interior can be heated in low-temperature environments to prevent condensation or freezing from causing valve jamming and failure, ensuring that the drain and pressure relief function can still be reliably performed under severe cold conditions, and further improving the system's adaptability across the entire temperature range.

[0067] The following provides a detailed embodiment to illustrate a fuel cell power generation system.

[0068] like Figure 1 As shown, in one embodiment of this application, the fuel cell power generation system includes a hydrogen supply and circulation unit 10, a hydrogen safety emission unit 20, an air supply and bypass unit 30, a water and heat management unit 40, a fuel cell stack and reaction unit 50, and an electrical and control unit 60.

[0069] The hydrogen supply and circulation unit 10 is responsible for supplying clean, pressure-stable hydrogen to the anode of the fuel cell stack 500 and for recycling unreacted hydrogen.

[0070] like Figure 2 As shown, the hydrogen supply and circulation unit 10 includes: a hydrogen system 100, a shut-off valve 102, a first proportional valve 103, a second proportional valve 104, an ejector 105, a pressure relief valve 106, and a first sensor 107.

[0071] like Figure 2As shown, the hydrogen system 100 includes a hydrogen system controller 101 and a hydrogen storage cylinder (a conventional device, not shown in the figure). The full name of the hydrogen system controller 101 is Hydrogen Management System, abbreviated as HMS. The first end of the shut-off valve 102 is connected to the hydrogen system 100, specifically, the first end of the shut-off valve 102 is connected to the hydrogen system controller 101. The second end of the shut-off valve 102 is connected to the first end of the first proportional valve 103. The second end of the first proportional valve 103 is connected to the first end of the second proportional valve 104. The second end of the second proportional valve 104 is connected to the hydrogen inlet 510 of the fuel cell stack. A pressure relief valve 106 is disposed between the second end of the second proportional valve 104 and the hydrogen inlet 510 of the fuel cell stack. A first sensor 107 is also disposed between the second end of the second proportional valve 104 and the hydrogen inlet 510 of the fuel cell stack.

[0072] An ejector 105 is also provided between the second end of the second proportional valve 104 and the hydrogen inlet 510 of the fuel cell stack. A pressure relief valve 106 can be located between the ejector 105 and the first sensor 107. The ejector 105 can be a venturi tube, and its function is to draw hydrogen from the fuel cell stack hydrogen outlet 520 back to the fuel cell stack hydrogen inlet 510. The first port 211 of the liquid-water separator 210 is connected to the ejector 105.

[0073] High-pressure hydrogen gas, after being pressurized by shut-off valve 102, first proportional valve 103, and second proportional valve 104, enters the fuel cell stack hydrogen inlet 510 through ejector 105. Unreacted hydrogen gas discharged from fuel cell stack hydrogen outlet 520 is separated from water by liquid-water separator 210 and then guided back to fuel cell stack hydrogen inlet 510 through the return port of ejector 105, thus achieving circulation. First sensor 107 is used to detect the pressure of the hydrogen inlet section, and its signal is fed back to hydrogen system controller 101. First sensor 107 may include a pressure sensor.

[0074] The hydrogen safety emission unit 20 is responsible for diluting and discharging the liquid water generated by the reaction on the anode side of the fuel cell stack 500, as well as the hydrogen-containing waste gas discharged during purging. It is also equipped with a safety protection mechanism.

[0075] Please continue reading. Figure 2 The hydrogen safety emission unit 20 includes a liquid-water separator 210, a second sensor 220, a drain valve 230, and a one-way pressure relief line 240. The drain valve 230, also known as a tailpipe valve, has an electric heating function.

[0076] The liquid-water separator 210 has three ports. The first port 211 of the liquid-water separator 210 is connected to the ejector 105. The second port 212 of the liquid-water separator 210 is connected to the hydrogen outlet 520 of the fuel cell stack. The third port 213 of the liquid-water separator 210 is connected to the drain valve inlet 231. The second sensor 220 may include a pressure sensor. Additionally, a one-way pressure relief line 240 is provided, one end of which is connected to the pressure relief valve 106 in the hydrogen supply and circulation unit 10, and the other end is connected to point W between the turbine end outlet 303d and the silencer 309.

[0077] The drain valve outlet 232 is connected to point W. Optionally, the drain valve outlet 232 can be connected to the one-way pressure relief line 240, so that the hydrogen discharge line 250 and the one-way pressure relief line 240 share a section, saving piping space. The hydrogen discharge line 250 starts from the third interface 213 of the liquid-water separator 210, connects to point J on the one-way pressure relief line 240 via the drain valve 230, and then connects to point W. The drain valve 230 is installed on the hydrogen discharge line 250.

[0078] The air supply and bypass unit 30 is responsible for providing clean, dry, and pressurized air to the cathode of the fuel cell stack 500, and is provided with a bypass channel 310 for purging the turbine end 303f of the air compressor.

[0079] Please continue reading. Figure 2 The air supply and bypass unit 30 includes a chemical filter 301, an air mass flow meter 302, an air compressor 303, an intercooler 304, an air inlet valve 305, a third sensor 306, a fourth sensor 307, an air outlet valve 308, a silencer 309, a bypass channel 310, an electric stack blowing line 320, and a one-way valve 330. A bypass valve 313 is installed on the bypass channel 310.

[0080] Air outlet valve 308 can be a throttle valve.

[0081] The fuel cell stack air inlet 530 is connected to the first side of the air inlet valve 305. A third sensor 306 is connected between the fuel cell stack air inlet 530 and the first side of the air inlet valve 305. The third sensor 306 may include a pressure sensor and a temperature sensor.

[0082] The second side of the air inlet valve 305 is connected to the first port of the intercooler 304. The second port of the intercooler 304 is connected to the air compressor outlet 303b.

[0083] The fuel cell stack air outlet 540 is connected to the first side of the air outlet valve 308. A fourth sensor 307 is connected between the fuel cell stack air outlet 540 and the first side of the air outlet valve 308. The fourth sensor 307 may include a pressure sensor. The second side of the air outlet valve 308 is connected to the turbine end inlet 303c. The first end of the bypass valve 313 is connected to point X. Point X is a point on the line connecting the second side of the air inlet valve 305 and the first interface of the intercooler 304. The second end of the bypass valve 313 is connected to point Y. Point Y is a point on the line connecting the second side of the air outlet valve 308 and the turbine end inlet 303c. All the pipes on this route—air compressor outlet 303b → intercooler 304 → point X → bypass valve 313 → point Y → turbine end inlet 303c—form a bypass channel 310. The bypass channel 310 is the core part of this application. The air compressor inlet 303a is also connected to the first end of the air mass flow meter 302, and the second end of the air mass flow meter 302 is connected to the chemical filter 301. The turbine outlet 303d is also connected to the silencer 309.

[0084] In addition, the air supply and bypass unit 30 is also equipped with an electric fuel cell stack blowing line 320. The starting end of the electric fuel cell stack blowing line 320 is connected to the connecting line between the second interface of the intercooler 304 and the air compressor outlet end 303b, that is... Figure 2 Point H in the diagram. The end of the fuel cell stack purging line 320 first extends into the interior of the fuel cell stack 500, and then extends out of the fuel cell stack 500. A one-way valve 330 is also installed on the part of the fuel cell stack purging line 320 that extends out of the fuel cell stack 500, such as... Figure 2 As shown.

[0085] The hydrothermal management unit 40 is responsible for maintaining the fuel cell stack 500 within a suitable temperature range and for heating, circulating, and filtering the coolant.

[0086] Please continue reading. Figure 2 The water and heat management unit 40 includes a fifth sensor 401, a water pump 402, a particulate filter 403, a cooling fan 404, a water supply tank 405, a PTC liquid heating plate 406, an ion filter 407, a cooling water three-way valve 408, and a sixth sensor 409.

[0087] The second end of the water pump 402 is connected to the fuel cell coolant inlet 550 of the fuel cell stack 500. The first end of the water pump 402 is connected to the first end of the particulate filter 403. The second end of the particulate filter 403 is connected to the first end of the cooling fan 404. The second end of the cooling fan 404 is connected to the first port of the cooling water three-way valve 408.

[0088] The cooling water three-way valve 408 has three ports. The second port of the cooling water three-way valve 408 is connected to the fuel cell stack coolant outlet 560, thus forming a complete cooling circuit.

[0089] The PTC liquid heating plate 406 can be used as a cold start module. The first end of the PTC liquid heating plate 406 is connected to point Z.

[0090] Point Z is a point on the connecting pipeline between the first end of the water pump 402 and the first end of the particulate filter 403. The second end of the PTC liquid heating plate 406 is connected to the third interface of the cooling water three-way valve 408.

[0091] The first end of the makeup water tank 405 is connected to point K, and the second end of the makeup water tank 405 is connected to the first end of the ion filter 407. The second end of the ion filter 407 is connected to the fuel cell coolant outlet 560. Point K is located on the connecting pipeline between the first end of the particulate filter 403 and the first end of the water pump 402.

[0092] The connecting pipe between the second end of the ion filter 407 and the fuel cell coolant outlet 560 is called connecting pipe A, and the connecting pipe between the second port of the cooling water three-way valve 408 and the fuel cell coolant outlet 560 is called connecting pipe B. Connecting pipe A and connecting pipe B can share a common pipe.

[0093] The fifth sensor 401 is disposed on the connecting pipe between the fuel cell coolant inlet 550 and the second end of the water pump 402. The fifth sensor 401 may include a pressure sensor and a temperature sensor. The third interface of the intercooler 304 is connected to the connecting pipe between the fifth sensor 401 and the fuel cell coolant inlet 550.

[0094] The sixth sensor 409 is disposed on the connecting pipe between the fuel cell coolant outlet 560 and the second port of the cooling water three-way valve 408. The sixth sensor 409 may include a pressure sensor and a temperature sensor. The fourth port of the intercooler 304 is connected to the connecting pipe between the fuel cell coolant outlet 560 and the second end of the ion filter 407.

[0095] The fuel cell stack and reaction unit 50 includes fuel cell stack 500.

[0096] Please continue reading. Figure 2 The fuel cell stack 500 includes a hydrogen inlet 510, a hydrogen outlet 520, an air inlet 530, an air outlet 540, a coolant inlet 550, a coolant outlet 560, a single-cell voltage monitoring module 571, and a seventh sensor 572. The fuel cell stack 500 achieves a hydrogen-oxygen electrochemical reaction through bipolar plates and membrane electrodes to generate electricity, water, and heat.

[0097] The full name of the cell voltage monitoring module 571 is Cell Voltage Monitor, abbreviated as CVM. Cell voltage monitoring module 571 is used to monitor the voltage of individual cells. The seventh sensor 572 within the fuel cell stack 500 is a hydrogen concentration sensor. The hydrogen concentration sensor is used to detect the hydrogen concentration inside the fuel cell stack 500.

[0098] The electrical and control unit 60 is responsible for the conversion and distribution of electrical energy and the logic control of the system.

[0099] Please continue reading. Figure 2 The electrical and control unit 60 includes an air compressor driver 610, a DC-DC converter 612, and an air pump controller 613.

[0100] The air compressor driver 610 provides a three-phase drive connection for the air compressor 303. The DC-DC converter 612 is an all-in-one device that can include both a boost DC-DC module and a buck DC-DC module. One side of the air compressor driver 610 connects to the fuel cell stack 500, and the other side connects to the vehicle 70; the connection can be a power cable. The power cable consists of two wires: one connected to the positive terminal 501 of the fuel cell stack, and the other connected to the negative terminal 502. The fuel cell controller 611 can be integrated into the air compressor driver 610 or independently located in the fuel cell power generation system. Figure 2 In the illustrated embodiment, the fuel cell controller 611 is integrated into the air compressor driver 610. The fuel cell controller 611 is used to send control signals to each component in the fuel cell power generation system to control the operation of each component, thereby implementing the control method of the fuel cell power generation system to be mentioned in subsequent embodiments.

[0101] In order to enable a better understanding of the core inventive points of this application, the working principle of several core pipelines of this application is introduced below.

[0102] First, let's explain the working principle of the fuel cell stack blowing line 320.

[0103] The gas flow direction of the fuel cell purging line 320 is from point H to fuel cell 500, where the gas enters. The gas flow direction of the purging line 320 is from fuel cell 500 to check valve 330. The function of the purging line 320 is to purge gaseous water from inside the fuel cell 500 casing. The internal airtightness of fuel cell 500 cannot be absolutely perfect; that is, the fuel cell 500 casing cannot be completely sealed. If the internal structure of fuel cell 500 is not purged, water may accumulate inside, causing malfunctions.

[0104] The bypass channel 310 and the fuel cell stack purging line 320 work together. The conventional solution does not have a bypass channel 310. If you want to start the machine to purge the fuel cell stack 500, you must close the air inlet valve 305 and the air outlet valve 308. This is a fixed procedure specified in the fuel cell stack 500's manual. If the air inlet valve 305 and the air outlet valve 308 are not closed, the fuel cell stack 500 will experience surge and is prone to failure and damage.

[0105] In the traditional approach, closing the air inlet valve 305 and the air outlet valve 308 results in insufficient flow from the air compressor 303, making it unable to effectively purge the interior of the fuel cell stack 500. However, this application, by opening the bypass channel 310, increases the flow rate of the air compressor 303 even when the air inlet valve 305 and the air outlet valve 308 are closed. This allows the air compressor 303 to not only support purging of the fuel cell stack via the fuel cell stack blowing line 320 but also to support purging of the air compressor turbine end 303f via the bypass channel 310. Therefore, the traditional approach without the bypass channel 310 cannot purge the interior of the fuel cell stack 500 due to insufficient flow, nor can it purge the air compressor turbine end 303f because the structure lacks this function. This application, by incorporating the bypass channel 310, can simultaneously purge both the interior of the fuel cell stack 500 housing and the air compressor turbine end 303f, achieving two goals at once.

[0106] It should be noted that the fuel cell stack purging line 320 operates as long as the air compressor 303 is in operation. That is, as long as the air compressor 303 is energized, the purging operation inside the fuel cell stack 500 will continue.

[0107] Secondly, the working principle of the hydrogen exhaust pipeline 250 of the 500 fuel cell stack will be explained.

[0108] The hydrogen discharge pipeline 250 refers to all the pipeline sections that start from the third port 213 of the liquid-water separator 210, pass through the drain valve 230, go to point J, to point W, and finally to the silencer 309. The first port 211 of the liquid-water separator 210 is connected to the ejector 105. The ejector 105 is a Venturi tube. The input side of the Venturi tube receives high-pressure hydrogen gas that has been compressed by the first proportional valve 103 and the second proportional valve 104. Due to its structural characteristics, the Venturi tube greatly accelerates the flow rate of the high-pressure hydrogen gas, turning it into high-pressure, high-speed hydrogen gas, which creates a negative pressure environment inside the Venturi tube. The negative pressure environment draws in the hydrogen gas delivered through the first port 211 of the liquid-water separator 210. This hydrogen gas is delivered through the hydrogen outlet 520 of the fuel cell stack, thus forming a hydrogen gas circulation on the anode side of the fuel cell stack 500: ejector 105 to fuel cell stack hydrogen inlet 510 to fuel cell stack hydrogen outlet 520 to the first port 211 of the liquid-water separator 210 to ejector 105.

[0109] During the continuous hydrogen circulation process on the anode side of this fuel cell stack 500, overflowing hydrogen will be generated and needs to be discharged. In this application, it is discharged through hydrogen discharge pipeline 250, which is the "hydrogen tail discharge" or "tail discharge" mentioned in this application.

[0110] Hydrogen gas is normally emitted through exhaust pipe 250 and eventually exits from muffler 309. However, determining the hydrogen concentration in the exhaust cannot be done solely by looking at the hydrogen concentration in the gas emitted from exhaust pipe 250; it must be calculated by mixing it with other emitted gases. As mentioned earlier, the composite gas emitted from muffler 309 consists of three streams: the exhaust gas, the main air stream, and the recirculated air stream. The main air stream and the recirculated air stream both exit through turbine outlet 303d, and after mixing with the exhaust gas from exhaust pipe 250 at point W, they form a composite gas that exits from muffler 309 together. Therefore, the "exhaust hydrogen concentration" is actually a calculation of the hydrogen concentration in this composite gas stream.

[0111] The airflow flowing through the hydrogen exhaust pipe 250 is the aforementioned tail exhaust flow, which has a very high hydrogen concentration. Without the bypass channel 310, the air compressor 303 has a relatively small flow rate, and the amount of gas discharged through the turbine outlet 303d is small, making it difficult to dilute the hydrogen concentration in the gas discharged from the hydrogen exhaust pipe 250. In other words, the overall hydrogen concentration of the composite gas cannot be significantly reduced. Especially during the first hydrogen exhaust after startup, the flow rate is small when the main airflow is just established. Tests have shown that this fails to meet the requirements of a peak hydrogen tail exhaust concentration of less than or equal to 8% and an average hydrogen tail exhaust concentration of less than or equal to 4%.

[0112] With the bypass channel 310 provided in this application, the flow rate of the air compressor 303 is increased, the amount of gas discharged through the turbine outlet 303d increases, the hydrogen concentration in the gas discharged through the hydrogen discharge pipeline 250 is diluted, and the overall hydrogen concentration of the composite gas is significantly reduced.

[0113] Thirdly, the working principle of the one-way pressure relief pipeline 240 will be introduced.

[0114] One end of the one-way pressure relief line 240 is connected to the pressure relief valve 106, and the other end of the one-way pressure relief line 240 is connected to point W. The one-way pressure relief line 240 is actually a safety protection device. The pressure relief valve 106 can be configured to automatically open once the pressure on the one-way pressure relief line 240 exceeds a preset pressure threshold, so that the pressure can be released quickly.

[0115] This application also provides a control method for a fuel cell power generation system.

[0116] The control method for the fuel cell power generation system does not limit the executing entity. Optionally, the executing entity of the control method for the fuel cell power generation system can be the fuel cell power generation system mentioned in any of the foregoing embodiments. Optionally, the executing entity can be the fuel cell controller 611 in the fuel cell power generation system mentioned in any of the foregoing embodiments.

[0117] In one embodiment of this application, the control method of the fuel cell power generation system is applied to any of the aforementioned embodiments of the fuel cell power generation system.

[0118] like Figure 3 As shown, the control method of the fuel cell power generation system includes: During the power-on phase, S100 executes the first control strategy.

[0119] During the shutdown phase, the S200 executes the second control strategy.

[0120] S100 includes, that is, during the power-on phase, executing the first control strategy includes the following S110 to S130, such as... Figure 4 As shown: S110, in response to receiving the start command, controls the bypass channel 310 to open and starts the air compressor 303, so as to establish a circulating air flow from the air compressor outlet end through the bypass channel 310 to the turbine inlet end 303c.

[0121] S120, after the circulating airflow is established, the hydrogen supply and circulation unit 10 is controlled to supply hydrogen to the anode of the fuel cell stack 500.

[0122] S130, control the air inlet valve 305 to open, so as to establish the main air flow from the air compressor outlet end 303b through the cathode of the fuel cell stack 500 to the turbine inlet end 303c.

[0123] S200 includes, that is, during the shutdown phase, executing the second control strategy includes, as follows: Figure 5 As shown: S210, in response to receiving a shutdown command, close the air inlet valve 305 and the air outlet valve 308.

[0124] S220, keep the bypass channel 310 open, and control the air compressor 303 to continue running for a predetermined time so as to purge the air compressor turbine end 303f of the air compressor 303 by means of the circulating air flow.

[0125] Specifically, in step S110, the start-up command can come from the vehicle control unit (VCU) built into the vehicle 70 or from a start signal from the driver. Upon receiving this command, the fuel cell controller 611 first sends an opening signal to the bypass valve 313 and simultaneously sends a start command to the air compressor driver 610. The air compressor 303 begins to accelerate from a standstill to the target idle speed (e.g., 5000-10000 rpm). Because the bypass channel 310 is open, compressed air does not enter the fuel cell stack 500 but returns to the turbine inlet 303c via the bypass channel 310, forming a cycle. This process lasts approximately 1 to 3 seconds, sufficient for initial purging of the air compressor turbine end 303f.

[0126] In step S120, after the circulating air flow stabilizes, the system activates the hydrogen supply and circulation unit 10. Specifically, the fuel cell controller 611 first opens the shut-off valve 102, and then adjusts the first proportional valve 103 and the second proportional valve 104 to bring the hydrogen pressure to the required value of the hydrogen pressure at the fuel cell stack hydrogen inlet 510. The required hydrogen pressure at the fuel cell stack hydrogen inlet 510 can be a relative pressure of 1.0 bar to 1.5 bar. At the same time, the tail valve on the anode side, i.e., the drain valve 230, also opens according to a certain duty cycle to discharge oxygen or nitrogen from the anode, accelerating hydrogen filling.

[0127] In step S130, after the hydrogen supply is established and the circulating air flow is stable, the fuel cell controller 611 opens the air inlet valve 305. The air inlet valve 305 is fully or partially open, so that the compressed air output from the air compressor 303 no longer entirely flows through the bypass channel 310, but instead mostly enters the cathode of the fuel cell stack 500. Thus, a cathode-air interface begins to form inside the fuel cell stack 500, the oxygen reduction reaction begins, and the open-circuit voltage is rapidly established. According to actual tests, compared to the traditional method of opening the air inlet valve first and then starting the air compressor 303, this strategy shortens the open-circuit voltage establishment time by approximately 2.4 seconds.

[0128] S120 and S130 can be considered to have been carried out almost simultaneously.

[0129] In step S210, upon receiving a shutdown command, the control system first closes the air inlet valve 305 and the air outlet valve 308. After these two valves are closed, the fuel cell stack 500 is isolated from the relevant air circulation piping, and the internal reaction of the fuel cell stack 500 quickly stops.

[0130] In step S220, after the air inlet valve 305 and air outlet valve 308 are closed, the control system does not immediately stop the air compressor 303. Instead, it maintains the open state of the bypass valve 313 and allows the air compressor 303 to continue running at idle speed or a slightly higher speed (e.g., 8000-12000 rpm) for a predetermined time. During this time, the bypass channel 310 continues to operate. This predetermined time can be a fixed value, such as 10 seconds, or a value dynamically calculated based on sensor data. During this period, the air compressor 303 repeatedly blows the air compressor turbine end 303f and the inner wall of the pipe through the circulating air flow established by the bypass channel 310, dispersing, heating, and evaporating residual moisture, which is finally discharged from the system through the air compressor turbine end 303f. Actual measurements show that after 10 seconds of such blowing, the system insulation resistance increases from 1.74 megohms to over 2.5 megohms, and the hydrogen concentration in the casing of the air compressor 303 decreases from 1130 ppm to below 100 ppm.

[0131] In this embodiment, the control method is divided into a first control strategy for the start-up phase and a second control strategy for the shutdown phase, with specific steps defined for each: during start-up, the bypass channel 310 is first opened to establish a circulating air flow, then hydrogen is supplied, and finally the main circuit is opened; during shutdown, the main circuit valve is first closed, then the bypass channel 310 is maintained and the air compressor 303 continues to run for a predetermined time. The first control strategy achieves early dilution of the exhaust hydrogen at the moment of start-up and accelerates the establishment of the open-circuit voltage; the second control strategy ensures continuous purging of the air compressor turbine end 303f after shutdown. Based on the above timing control, this control method, through software-level strategy optimization and deep collaboration with the hardware bypass structure, achieves a dual improvement in system insulation performance and start-up response speed at extremely low cost.

[0132] In one embodiment of this application, the control method of the fuel cell power generation system further includes: S140, after the main airflow is established, the drain valve 230 is opened. The circulating airflow is used to dilute the hydrogen concentration in the hydrogen-containing waste gas discharged from the drain valve 230.

[0133] Specifically, step S140 follows step S130. Specifically, after the air inlet valve 305 opens and the main airflow is established, the fuel cell controller 611 controls the drain valve 230 to open according to a preset duty cycle (e.g., 0.5 seconds on, 2 seconds off) or a continuous opening mode. The opening of the drain valve 230 discharges the liquid water accumulated at the bottom of the liquid-water separator 210 and the unused hydrogen on the anode side of the fuel cell stack 500 to the turbine outlet 303d.

[0134] In this embodiment, the drain valve 230 is opened after the circulating air flow and main air flow are established, so that the hydrogen-containing waste gas discharged from the drain valve 230 is diluted by the established circulating air flow and main air flow. Especially during the first hydrogen discharge after startup, the flow rate of the main air flow is small when it is first established, and the circulating air flow plays a dominant role in diluting the hydrogen concentration. This timing arrangement avoids the lag problem of hydrogen accumulating first and then being diluted, ensuring the synchronicity and high efficiency of the dilution process, and controlling the peak concentration of exhaust hydrogen below the safe threshold.

[0135] In one embodiment of this application, the control method of the fuel cell power generation system further includes: S131, at the instant the air inlet valve 305 is opened, a pulse with a large air flow is generated to reduce the peak value of hydrogen concentration in the hydrogen-containing waste gas discharged from the drain valve 230.

[0136] Specifically, step S131 is an instantaneous control action added to step S130. In the conventional scheme, after the air inlet valve 305 opens, the air compressor 303 maintains a constant speed, and the air flow gradually increases. However, in this application, at the same time as the air inlet valve 305 opens or for a very short time (e.g., within 50 milliseconds), the target speed of the air compressor 303 is temporarily increased (e.g., instantly increased from idle speed of 8000 rpm to 15000 rpm), or the opening of the bypass valve 313 is temporarily closed, forcing more air to flow through the main circuit into the fuel cell stack 500, thereby generating a large air flow pulse at the air inlet valve 305 lasting approximately 0.2 to 0.5 seconds. The peak air flow of this large air flow pulse can be 1.5 to 2 times the steady-state flow.

[0137] This large airflow pulse increases the amount of air entering the cathode of fuel cell stack 500, rapidly replacing the original inert gases such as nitrogen inside stack 500 and accelerating the establishment of open-circuit voltage. Combined with the dilution effect of the circulating airflow, it further smooths out the spike waveform of the exhaust hydrogen concentration.

[0138] In this embodiment, a large airflow pulse is generated at the instant the air inlet valve 305 opens, creating an instantaneous strong dilution effect on the hydrogen-containing waste gas discharged from the drain valve 230. This pulse flow can effectively smooth out the peak waveform of the hydrogen concentration in the tail gas, avoiding triggering alarms or safety interlocks due to instantaneous exceedance of hydrogen concentration at the beginning of startup, thus improving the safety margin and smoothness of the startup process.

[0139] In one embodiment of this application, the predetermined time is dynamically determined based on one or more of the following parameters: air compressor temperature, ambient temperature, and the amount of liquid water discharged from the fuel cell air outlet 540.

[0140] Specifically, this embodiment further describes the predetermined time in S220. The predetermined time is not a fixed value, but rather an adaptive duration calculated in real time by the control system. Specifically: Parameter 1: Air compressor temperature. At least one temperature sensor can be installed on the housing of air compressor 303 or the outer casing of air compressor turbine end 303f. When the temperature of air compressor 303 is low, moisture does not evaporate easily, requiring a longer purging time. A minimum temperature threshold, such as 10 degrees Celsius, can be set, and a first preset purging time, such as 30 seconds, can be set. That is, when the air compressor temperature is less than or equal to 10 degrees Celsius, the preset time in S220 applies the first preset purging time, continuously purging air compressor turbine end 303f for 30 seconds.

[0141] When the temperature is high, moisture evaporates quickly, so the purging time can be shortened. A maximum temperature threshold can be set, such as 50 degrees Celsius, and a second preset purging time can be set, such as 5 seconds. That is, when the air compressor temperature is greater than or equal to 50 degrees Celsius, the preset time in S220 applies the second preset purging time, and the air compressor turbine end 303f is continuously purged for 5 seconds.

[0142] Parameter 2: Ambient Temperature. An ambient temperature sensor is used to obtain the ambient temperature. When the ambient temperature is less than or equal to 0 degrees Celsius, there is a risk of icing, requiring a longer purging time to ensure complete removal of moisture. When the ambient temperature is greater than or equal to 20 degrees Celsius, even if a small amount of moisture remains, icing is less likely, and the purging time can be appropriately shortened.

[0143] Parameter 3: The amount of liquid water discharged from the fuel cell air outlet 540. This parameter can be measured indirectly or directly by installing a humidity sensor or liquid flow meter downstream of the fuel cell air outlet 540. A larger liquid water volume means more moisture may accumulate at the compressor turbine end 303f, requiring a correspondingly longer purging time. For example, when the detected liquid water flow rate is greater than or equal to 10 ml / min, the predetermined time in S220 is set to 20 seconds. When the detected liquid water flow rate is less than 2 ml / min, the predetermined time in S220 is set to 8 seconds.

[0144] Optionally, in one embodiment, the fuel cell controller 611 calculates the optimal purging time based on the above parameters using a pre-calibrated function or a lookup table. For example, the optimal purging time can be calculated using a simple linear formula: T = T_base × K_temp × K_water, where T_base is the base time, K_temp is the temperature correction coefficient, K_water is the water volume correction coefficient, and T is the optimal purging time. The final calculated T value is then used as the predetermined time in S220. T_base can be set to 10 seconds, K_temp can be set to any value within the range of 0.5 or greater and less than or equal to 2, and K_water can be set to any value within the range of 1 or greater and less than or equal to 3.

[0145] In this embodiment, the predetermined running time of the air compressor 303 is dynamically determined based on parameters such as the air compressor temperature, ambient temperature, and the amount of liquid water discharged from the fuel cell air outlet 540. This achieves adaptive adjustment of the purging time: when the ambient temperature is low or the amount of liquid water is high, the purging time is automatically extended until the water is fully removed; conversely, the purging time is shortened to reduce energy consumption. This adaptive strategy avoids insufficient water removal or energy waste that may result from fixed-time purging, achieving an optimal balance between water removal effect and system efficiency.

[0146] In one embodiment of this application, the control method of the fuel cell power generation system further includes: S150, after the air inlet valve 305 is opened, the voltage of a single cell of the fuel cell stack 500 is monitored. When the lowest single cell voltage reaches a preset voltage threshold, the fuel cell stack 500 is controlled to output idle current.

[0147] Specifically, S150 can be executed after S130. The fuel cell stack 500 integrates a cell voltage monitoring module 571, abbreviated as CVM. This module monitors the voltage of each individual cell in real time and identifies the lowest voltage value, known as the minimum cell voltage, representing the capability of the "weakest" cell. The fuel cell controller 611 reads this minimum cell voltage.

[0148] The preset voltage threshold can be set to 0.91 volts (hereinafter referred to as V). This preset voltage threshold is determined based on the corrosion rate of the membrane electrode catalyst under open-circuit voltage: when the voltage exceeds 0.9V, the risk of carbon support corrosion increases significantly. Therefore, once the minimum single-cell voltage reaches or exceeds 0.91V, it indicates that the fuel cell stack 500 has sufficient chemical reactivity and can begin to carry a load. At this time, the fuel cell controller 611 immediately sends a command to the DC-DC converter 612, requesting the fuel cell stack 500 to output a preset idle current, which can be 5 amps to 20 amps. After outputting the idle current, the voltage of the fuel cell stack 500 will immediately drop to the safe operating range of 0.7V-0.8V, thereby preventing the fuel cell stack 500 from remaining in an open-circuit voltage state for a long time.

[0149] Compared to traditional strategies that wait for all individual cell voltages to stabilize or wait a fixed delay before outputting current, this application controls the fuel cell stack 500 to immediately output idle current after the minimum single-cell voltage is met, reducing the open-circuit voltage duration from approximately 5 seconds to less than 2.6 seconds. This significantly reduces the electrochemical corrosion of the catalyst by high potential and extends the service life of the fuel cell stack 500.

[0150] In this embodiment, by monitoring the individual cell voltage of the fuel cell stack 500 after the control air inlet valve 305 is opened, and immediately controlling the fuel cell stack 500 to output idle current when the lowest individual cell voltage reaches a preset voltage threshold, the duration of open-circuit voltage from power-on to current output is significantly shortened. Open-circuit voltage has a corrosive effect on the catalyst of the fuel cell stack 500; reducing its duration can effectively delay catalyst degradation and extend the service life of the fuel cell stack 500. Actual measurement data shows that this strategy can shorten the open-circuit voltage duration of traditional solutions by more than 2.4 seconds.

[0151] In a complete control process for a fuel cell power generation system, the technical solutions of the above embodiments can be coupled and work together. The following specific operational example will connect these embodiments in series.

[0152] Before system startup, the ambient temperature was -5 degrees Celsius, and the air compressor turbine end 303F may contain residual condensate from the previous shutdown. The vehicle controller sends a startup command to the fuel cell power generation system. The fuel cell power generation system starts up.

[0153] First, the fuel cell power generation system executes the first control strategy during the start-up phase. The fuel cell controller 611 controls the bypass valve 313 to open and starts the air compressor 303. The air compressor 303 accelerates to 8000 rpm, establishing a circulating airflow from the air compressor outlet 303b through the bypass channel 310 back to the turbine inlet 303c. This circulating airflow begins to purge the air compressor turbine end 303f.

[0154] Next, approximately one second after the recirculating airflow is established, the fuel cell controller 611 controls the hydrogen supply unit to supply hydrogen to the anode of the fuel cell stack 500, and simultaneously controls the air inlet valve 305 to open. The main airflow is then established. Following this, the heated drain valve 230 is opened with a duty cycle of 0.5 seconds to 2 seconds. The hydrogen-containing exhaust gas discharged from the drain valve 230 mixes with the air discharged from the turbine end outlet 303d and is rapidly diluted by the recirculating airflow until the hydrogen concentration is below 6%.

[0155] Furthermore, at the instant the air inlet valve 305 opens, the fuel cell controller 611 temporarily increases the speed of the air compressor 303 to 15,000 rpm, generating a large airflow pulse to further reduce the peak of the exhaust hydrogen concentration. Subsequently, the air inlet valve 305 remains open, the main airflow is established, and an open-circuit voltage begins to be generated inside the fuel cell stack 500.

[0156] After the air inlet valve 305 opens, the fuel cell controller 611 continuously monitors the voltage of each cell in the fuel cell stack 500 via the cell voltage monitoring module 571. When the lowest cell voltage is detected to reach 0.91V, the controller immediately controls the DC-DC converter 612 to draw 15 amps of idle current from the fuel cell stack 500. At this time, the voltage of the fuel cell stack 500 stabilizes at 0.75V, and the open-circuit state lasts for less than 1 second.

[0157] After the system has been running normally for a period of time, the vehicle controller issues a shutdown command. The fuel cell power generation system then enters the shutdown state.

[0158] At this point, the second control strategy for the shutdown phase is executed. The fuel cell controller 611 immediately closes the air inlet valve 305 and the air outlet valve 308. After both valves are closed, the bypass valve 313 remains open, and the air compressor 303 continues to operate at 8000 rpm. Based on the current ambient temperature of -5°C, the air compressor casing temperature of 15°C, and the average liquid water discharge rate of 8 ml / min in the last 10 seconds before the fuel cell stack 500 shuts down, the fuel cell controller 611 dynamically calculates the optimal purging time to be 25 seconds. During these 25 seconds, the circulating airflow continuously purges the air compressor turbine end 303f, gradually removing residual moisture. After 25 seconds, the fuel cell controller 611 stops the air compressor 303 and closes the bypass valve 313. After shutdown, the system insulation resistance is measured to be 2.55 megohms, and the residual hydrogen concentration in the casing is 70 ppm. ppm is an abbreviation for parts per million, a unit of measurement for concentration, frequency error, etc.

[0159] To demonstrate the beneficial effects of the fuel cell power generation system and control method provided in this application, experiments were conducted.

[0160] Figure 6 This is a comparison chart showing the hydrogen concentration in the tailrace and the opening / closing state of the drain valve after using the conventional method and the method provided in this application. The blue line is the corresponding left vertical axis, i.e., the hydrogen concentration in the tailrace. The red line is the corresponding right vertical axis, i.e., the opening / closing state of the drain valve, with only two states: 0 represents the drain valve being closed, and 1 represents the drain valve being open. Figure 6 (a) in the text is the traditional scheme. Figure 6 (b) in the figure represents the scheme of this application. It can be seen that, compared with the traditional scheme, the hydrogen concentration in the tail exhaust is significantly reduced, and the hydrogen concentration at the peak point is significantly reduced. The scheme of this application does not have a peak point with particularly high hydrogen concentration in the tail exhaust.

[0161] Figure 7 This is a comparison diagram showing the air compressor speed, the opening degree of air inlet valve 305, the opening degree of air outlet valve 308, and the opening degree of bypass valve 313 after using the conventional solution and the solution provided in this application. In this diagram, the blue line represents the air compressor speed, the yellow line represents the opening degree of air outlet valve 308, and the gray line represents the opening degree of bypass valve 313. The opening degree of air outlet valve 308 is consistent with the opening degree of air inlet valve 305, that is, air inlet valve 305 and air outlet valve 308 open and close simultaneously, represented by the same line, i.e., the yellow line. Figure 7 (a) in the text is the traditional scheme. Figure 7 (b) in the diagram represents the solution of this application. It can be understood that this diagram illustrates that the control method of the solution provided in this application differs from traditional solutions. In the solution provided in this application, the air compressor 303 also starts simultaneously when the bypass valve 313 opens. The air compressor 303 and the bypass valve 313 open synchronously, but the speed of the air compressor 303 increases gradually. The air inlet valve 305 opens after the air compressor 303 and the bypass valve 313 have opened. Figure 7 As shown, the air compressor 303 and the bypass valve 313 open simultaneously at second 0, and the air inlet valve 305 and the air outlet valve 308 both open simultaneously at second 8.

[0162] Figure 8 A comparison chart showing airflow rates after using the conventional method and the method provided in this application. Combined with... Figure 6 , Figure 8 (a) in the text is the traditional scheme. Figure 8 (b) in the figure is the scheme of this application. Figure 7 and Figure 8 Looking at it together, it's understandable that in the traditional solution, the air inlet valve 305 opens synchronously with the air compressor 303, without a pulse. Figure 6 Around the 3rd second, in the conventional scheme, there is a very high hydrogen concentration spike immediately after the air inlet valve 305 opens. However, the scheme in this application, due to... Figure 8As can be seen, a large airflow pulse was used after opening the air inlet valve 305, which can reduce the peak hydrogen concentration in the exhaust. Figure 6 The scheme provided in this application does not have a particularly high hydrogen concentration peak.

[0163] Figure 9 A comparison chart of stack current and minimum unit voltage during the startup phase, using both conventional and the solutions provided in this application. Figure 9 The blue line corresponds to the left vertical axis, which is the stack current, and the red line corresponds to the right vertical axis, which is the minimum unit voltage. Figure 9 (a) in the text is the traditional scheme. Figure 9 (b) in this application represents the proposed solution. The start point of the open-circuit voltage duration is the time point corresponding to the first time the lowest single-cell voltage reaches 0.91 volts. The end point of the open-circuit time is actually equivalent to the current establishment time point, which is the time point when the current starts to rise from 0 amps.

[0164] The current settling time is not a stable constant value. It is determined by complex factors such as the structure of the fuel cell power generation system and the performance of the battery pack. The way to obtain it is to find out the appropriate time point for current settling through experiments. If the current is settling immediately after the lowest single-cell voltage first reaches 0.91 volts, the device will fail and be scrapped.

[0165] Figure 9 The results obtained through experiments show that... Figure 9 (b) in the figure is the solution of this application. The technical solution of this application establishes the current more quickly because the current feedback is faster. As long as the current is established, the blue line part in the figure will generate a value, and there is almost no delay. Figure 9 (a) and Figure 9 The duration of the lowest single-cell voltage being below 0 volts in (b) varies, but this does not affect the Figure 9 (a) and Figure 9 The comparison between (b) is important because the focus of the comparison is on the duration of the open-circuit voltage, rather than the duration of the time when the lowest single-cell voltage is below 0 volts.

[0166] Figure 9As can be seen, the solution provided in this application establishes the fuel cell stack current much faster than the traditional solution, achieving it in just 4 seconds, while the traditional solution establishes the current around 6.5 seconds. Therefore, the air compressor 303 starts up much faster with the solution provided in this application. The open-circuit voltage duration t(a) of the traditional solution is more than 1 second, while the open-circuit voltage duration t(b) of the solution provided in this application is shortened to less than 1 second. The shorter the open-circuit voltage duration, the shorter the duration of the high potential during fuel cell startup, and consequently, the less corrosive the high potential is to the fuel cell catalyst.

[0167] Figure 10 A comparison diagram of the air compressor speed, the opening degree of the air inlet valve 305, and the opening degree of the bypass valve 313 during the start-up phase, after using the conventional solution and the solution provided in this application. Figure 10 In the diagram, the blue line represents the air compressor speed, the red line represents the opening degree of the air inlet valve 305, and the gray line represents the opening degree of the bypass valve 313. Figure 10 and Figure 7 similar, Figure 10 The 0th second is actually Figure 7 Around the 5th second, that is Figure 10 yes Figure 7 A portion of it was extracted. Figure 10 (a) in the text is the traditional scheme. Figure 10 (b) in the figure is the scheme of this application. Figure 10 This demonstrates that the control method of the solution provided in this application differs from the traditional solution in its start-up process. In the solution provided in this application, the bypass valve 313 and the air compressor 303 are opened simultaneously and immediately upon start-up, resulting in a rapid increase in air compressor speed. The air inlet valve 305 opens 2.4 seconds after the air compressor 303 and bypass valve 313 have opened.

[0168] Figure 11 This graph compares the air inlet pressure during startup using both the conventional and the proposed solutions. It illustrates the difference between the proposed solution and the conventional solution in establishing the air inlet pressure. Figure 11 (a) in the text is the traditional scheme. Figure 11 (b) in this application represents the proposed solution. The conventional solution establishes the air inlet pressure by adjusting the compressor speed after startup. However, the proposed solution establishes the air inlet pressure using a bypass valve 313.

[0169] Figure 12 The diagram shows the parameters of the fuel cell stack current and minimum individual cell voltage during the shutdown phase after using the solution provided in this application. Figure 13 The diagram shows the parameters of the air compressor speed, the opening degree of the air inlet valve 305, and the opening degree of the bypass valve 313 during the shutdown phase after using the solution provided in this application. Figure 14These three graphs show the parameters of the air inlet pressure during the shutdown phase after using the scheme provided in this application. Only the scheme of this application is shown in these three graphs; traditional schemes are not included. These graphs represent our shutdown strategy: when the air inlet valve 305 is closed, the bypass valve 313 immediately opens. At this time, by continuously consuming current, the air on the cathode side of the fuel cell stack 500 is completely consumed, and the single-cell voltage drops to zero. Therefore, from the perspective of the lowest single-cell voltage, it will gradually become 0. Simultaneously, the air compressor 303 can continue to operate for approximately 10 seconds after the air inlet valve 305 and the air outlet valve 308 are closed. This 10-second purging of the air compressor turbine end 303f aims to reduce the residual hydrogen concentration in the casing and also reduce the residual liquid water in the casing of the air compressor 303.

[0170] We also conducted a post-purge parameter acquisition experiment on the shutdown strategy. After shutdown, the air compressor turbine end 303f was purged for 10 seconds, and the results are shown in Table 1 below.

[0171] Table 1 - Comparison of parameters between the traditional solution and the solution provided in this application during the shutdown phase. System insulation resistance (MΩ) 1.74 2.02 2.42 2.55 2.66 One hour later, the residual hydrogen concentration (ppm) on the fuel cell stack casing. 1130 69 72 70 43 We observed that by modifying the shutdown strategy, the system insulation resistance gradually increased from 1.74 MΩ to approximately 2.5 MΩ. Simultaneously, the residual hydrogen concentration inside the casing decreased from over 1000 ppm to below 100 ppm.

[0172] Tests 1 through 4 all used the scheme provided in this application and were essentially no different. Multiple tests were conducted simply to minimize the error in the collected parameters. Each of the four tests involved a 10-second purging process to remove residual hydrogen. If there was water vapor at the turbine end (303F) of the air compressor or inside the casing of the fuel cell stack (500), the system insulation resistance would decrease. If the system insulation resistance was greater than 2 MΩ, it indicated that the technical solution of this application was effective. Whether the purging duration was 10 seconds or another duration is not crucial; this is merely an example, and it is difficult to exhaustively list all test data for purging durations.

[0173] As can be seen, under the action of the bypass channel 310, not only is the internal water vapor removed from the air compressor turbine end 303f due to purging, which is reflected in the increasing insulation resistance of the system, but the residual hydrogen concentration in the fuel cell stack 500 shell is also decreasing, indicating that the purging of the fuel cell stack 500 by the fuel cell stack blowing pipeline 320 is also operating normally under the action of the bypass channel 310.

[0174] The technical features of the above embodiments can be combined arbitrarily, and the execution order of the method steps is not restricted. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0175] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A fuel cell power generation system, characterized in that, include: The fuel cell stack has an air inlet and an air outlet. An air compressor has an air compressor inlet end for receiving air and an air compressor outlet end for outputting compressed air; the air compressor also includes a turbine end inlet end and a turbine end outlet end. An air inlet valve is connected between the air compressor outlet and the fuel cell air inlet. An air outlet valve is connected between the fuel cell stack air outlet and the turbine end inlet. A bypass channel includes a first bypass channel end and a second bypass channel end. The first bypass channel end is connected to the air line between the air compressor outlet end and the air inlet valve, and the second bypass channel end is connected to the air line between the air outlet valve and the turbine inlet end. When the fuel cell power generation system is in the start-up phase and / or in the shutdown phase, the bypass channel is controlled to open to establish a circulating airflow from the air compressor output and then back to the air compressor via the bypass channel. This circulating airflow is used to purge the air compressor turbine end of the air compressor. The fuel cell stack also includes a hydrogen outlet connected to a liquid-water separator, and the fuel cell power generation system further includes: A drain valve includes a drain valve inlet and a drain valve outlet, wherein the drain valve inlet is connected to the liquid-water separator and the drain valve outlet is connected to the turbine end outlet. The circulating airflow is also used to dilute the hydrogen-containing waste gas discharged from the drain valve when the fuel cell power generation system is in the start-up phase; The fuel cell power generation system also includes an intercooler, which is located between the air inlet valve and the air compressor outlet. The fuel cell stack air blowing line is connected at the beginning to the connecting line between the second interface of the intercooler and the outlet of the air compressor. The end of the fuel cell stack air blowing line extends into the interior of the fuel cell stack and then extends out of the fuel cell stack. A one-way valve is also installed on the part of the fuel cell stack air blowing line that extends out of the fuel cell stack. By opening the bypass channel, the air compressor flow rate can be increased even when the air inlet valve and air outlet valve are closed. This allows the air compressor flow rate to not only support the purging of the fuel cell stack through the fuel cell stack blowing line, but also to support the purging of the air compressor turbine end through the bypass channel. A bypass valve is disposed on the bypass channel and is used to control the opening and closing of the bypass channel; At the instant the air inlet valve opens, a pulse of large airflow is generated to reduce the peak value of hydrogen concentration in the hydrogen-containing waste gas discharged from the drain valve. The step of generating a large airflow pulse at the instant the air inlet valve opens to reduce the peak hydrogen concentration in the hydrogen-containing waste gas discharged from the drain valve includes: At the same time as the air inlet valve opens or within 50 milliseconds, the target speed of the air compressor is temporarily increased, or the opening of the bypass valve is temporarily reduced, so that more air flows through the main circuit into the fuel cell stack, generating a large air flow pulse lasting 0.2 to 0.5 seconds at the air inlet valve; the peak air flow of the large air flow pulse is 1.5 to 2 times the steady-state flow.

2. The fuel cell power generation system according to claim 1, characterized in that, The air compressor is a turbine air compressor equipped with a turbine kinetic energy recovery device.

3. The fuel cell power generation system according to claim 2, characterized in that, The drain valve is a solenoid valve with heating function.

4. A control method for a fuel cell power generation system, characterized in that, The method for controlling the fuel cell power generation system, applicable to any one of claims 1 to 3, comprises: During the power-on phase, the first control strategy is executed; During the shutdown phase, the second control strategy is executed; The execution of the first control strategy during the power-on phase includes: In response to receiving a start command, the bypass channel is opened and the air compressor is started to establish a circulating airflow from the air compressor outlet end through the bypass channel to the turbine inlet end; After the circulating airflow is established, the hydrogen supply and circulation unit are controlled to supply hydrogen to the anode of the fuel cell stack; The air inlet valve is opened to establish a main airflow from the air compressor outlet end through the cathode of the fuel cell stack to the turbine inlet end; During the shutdown phase, the execution of the second control strategy includes: In response to receiving a shutdown command, the air inlet valve and the air outlet valve are closed; The bypass channel is kept open, and the air compressor is controlled to continue running for a predetermined time so as to purge the air compressor turbine end of the air compressor through the circulating air flow; The control method for the fuel cell power generation system further includes: After the main airflow is established, the drain valve is opened; the circulating airflow is used to dilute the hydrogen concentration in the hydrogen-containing waste gas discharged from the drain valve. By opening the bypass channel, the air compressor flow rate can be increased even when the air inlet valve and air outlet valve are closed. This allows the air compressor flow rate to not only support the purging of the fuel cell stack through the fuel cell stack blowing line, but also to support the purging of the air compressor turbine end through the bypass channel. The control method for the fuel cell power generation system further includes: At the instant the air inlet valve opens, a pulse of large airflow is generated to reduce the peak value of hydrogen concentration in the hydrogen-containing waste gas discharged from the drain valve. The step of generating a large airflow pulse at the instant the air inlet valve opens to reduce the peak hydrogen concentration in the hydrogen-containing waste gas discharged from the drain valve includes: At the same time as the air inlet valve opens or within 50 milliseconds, the target speed of the air compressor is temporarily increased, or the opening of the bypass valve is temporarily reduced, so that more air flows through the main circuit into the fuel cell stack, generating a large air flow pulse lasting 0.2 to 0.5 seconds at the air inlet valve; the peak air flow of the large air flow pulse is 1.5 to 2 times the steady-state flow.

5. The control method for the fuel cell power generation system according to claim 4, characterized in that, The predetermined time is dynamically determined based on one or more of the following parameters: air compressor temperature, ambient temperature, and the amount of liquid water discharged from the fuel cell air outlet.

6. The control method for the fuel cell power generation system according to claim 4, characterized in that, The control method for the fuel cell power generation system further includes: After the air inlet valve is opened, the voltage of each cell in the fuel cell stack is monitored. When the lowest voltage of a single cell reaches a preset voltage threshold, the fuel cell stack is controlled to output idle current.

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