A delayed shutdown purging method for a hydrogen fuel stack system

Abstract

The application provides a hydrogen fuel stack system delayed shutdown purging method, relates to the hydrogen fuel cell technical field, and is applied to a system comprising a battery module, a master control chip MCU, a non-self-locking switch, a main relay, a blower and a purging electromagnetic valve. The technical problem to be solved is to avoid purging interruption caused by immediate power-off during stack shutdown or to add an additional power supply unit to maintain purging. The core of the method is that the system is powered on through the non-self-locking switch, and the power supply is self-locked by the main relay attraction controlled by the MCU. When the switch is triggered again to send a shutdown signal, the MCU does not immediately cut off the power, but maintains the main relay attraction, continues to supply power by using the system battery, and controls the purging program to be executed. After the purging is completed, the MCU actively disconnects the main relay, cuts off the battery output, and realizes the system zero-power-off shutdown. The application can ensure that the shutdown purging is automatically and completely executed without an additional power supply, effectively protects the stack, and improves the system reliability.

Description

Technical Field

[0001] This invention relates to the field of hydrogen fuel cell technology, and in particular to a delayed shutdown purging method for a hydrogen fuel cell stack system. Background Technology

[0002] As the core power generation component of the system, the internal state of the hydrogen fuel cell stack after shutdown directly determines the success rate of the next startup, the safety of the system, and its long-term durability. Improper handling of the stack's internal state after system shutdown can lead to a series of problems: First, residual moisture in the cathode and anode channels can freeze in low-temperature environments (e.g., below 0°C), causing volume expansion that can lead to mechanical damage to the membrane electrode assembly (MEA), catalyst layer detachment, or destruction of the gas diffusion layer structure. Second, unreacted hydrogen remaining on the anode side may leak and accumulate, forming an explosive mixture and posing a serious safety hazard. Third, if oxygen and hydrogen remain at the anode and cathode respectively after shutdown, local reverse polarity may occur under conditions of circuit disconnection or voltage imbalance, leading to corrosion of the catalyst carbon support and irreversible degradation of the stack's performance. Fourth, if the humidity of the proton exchange membrane becomes unbalanced during long-term shutdown, whether due to excessive moisture leading to decreased mechanical strength or excessive dryness leading to decreased conductivity, it will affect the stack's lifespan and subsequent startup performance. Therefore, a comprehensive and reliable post-shutdown treatment strategy, especially an effective purging process, is crucial for ensuring the reliability of the hydrogen fuel cell system.

[0003] Currently, existing technical solutions for post-shutdown processing of fuel cell stacks can be mainly categorized as follows: First, passive natural decay shutdown: This is the most basic method. Upon receiving a shutdown command, the system immediately cuts off the hydrogen supply and disconnects the main circuit relay. The fuel cell stack relies on the connected load or natural processes to consume the remaining hydrogen until the output voltage drops to zero. This solution requires no additional control logic or actuators, resulting in the simplest system structure and lowest cost. Second, active timed purging: This method actively introduces a purging process after shutdown to improve the fuel cell stack's condition. The most common is the "simple cathode timed purging" solution, where after system shutdown, the controller controls the air compressor or blower to continue running for a preset time, introducing air (or dry gas) to the cathode side of the fuel cell stack to remove some moisture. After the purging time ends, the actuator stops, and the system is powered off. In addition, there are some improved solutions. For example, Chinese patent CN110768345A discloses a shutdown control method for a fuel cell system, which controls the air compressor to provide purging gas to the cathode after shutdown, with the purging time being a fixed value. Third, a delayed power-off scheme using independent hardware: To resolve the contradiction that the purging process requires power while the main switch has already cut off the power, some solutions introduce independent delayed power-off hardware. For example, Chinese patent CN112332390A describes a fuel cell system containing a time-delay relay, which can briefly maintain power supply to auxiliary equipment such as the blower after the system's main relay is disconnected. Another approach is to use a capacitor energy storage scheme, as described in US patent publication US20210384765A1, which uses a capacitor to briefly power the control unit after the main power is disconnected to perform data storage and simple purging operations. Although the above-mentioned existing technical solutions are designed to some extent for post-shutdown processing, they still have several obvious defects and cannot comprehensively, economically and reliably solve all the problems of fuel cell stack shutdown maintenance: (1) The passive natural decay scheme cannot remove liquid water inside the fuel cell stack, especially in the bipolar plate flow channel and diffusion layer. Therefore, when used in low-temperature environments, the fuel cell stack is very susceptible to freezing damage. At the same time, the residual hydrogen gas at the anode relies on natural consumption or reaction, which is a slow process with a long hydrogen gas retention time and a high safety risk. This scheme also does not actively manage the humidity of the proton exchange membrane at all. (2) Although the simple cathode timed purging scheme can partially solve the problem of residual moisture on the cathode side, it cannot effectively deal with residual hydrogen gas and moisture on the anode side. Only purging the cathode is not enough to effectively remove the moisture in the anode chamber through diffusion. More seriously, the unstable hydrogen-air interface may be formed on both sides of the membrane electrode due to the influence of the cathode purging gas pressure, which may increase the risk of carbon corrosion on the cathode side.(3) The control logic of the solution using independent timer relays and other hardware is fixed, and the purging time is usually a fixed value. It cannot be adaptively adjusted according to the actual operating conditions of the fuel cell stack (such as the cumulative power generation time, ambient temperature, internal humidity of the fuel cell stack, etc.), which is inflexible and may result in over-purging or under-purging in different application scenarios. In addition, adding independent timer relay modules also increases the hardware cost and complexity of the system. (4) The capacitor energy storage power supply solution is limited by the capacity and volume of the capacitor itself. The stored electrical energy is limited and can usually only provide power to low-power units such as microcontrollers for a short time. It is difficult to drive relatively high-power loads such as blowers for a sufficiently long effective purging time. If you want to extend the power supply time, you need to use large-capacity capacitors that are bulky and expensive, which is not suitable for commercial products that are sensitive to cost and space. (5) Fundamental power supply contradiction. In the conventional system architecture, the actuators (blowers, solenoid valves) and controllers (MCUs) required for purging all rely on the main power supply (battery) of the system. The user's shutdown operation usually directly affects the switch that controls the output of the main power supply. Once the switch is turned off, the battery output is immediately cut off, causing the purging process to fail to start or to abort midway. To resolve this issue, some designs employ complex solutions such as dual power supplies, further increasing system complexity and cost.

[0004] In summary, existing technical solutions are inadequate in terms of effectiveness, safety, economy, and reliability. There is an urgent need for an intelligent shutdown method that can utilize the system's own power supply to automatically and controllably purge the anode and cathode of the fuel cell stack, and completely de-energize the system after purging. Summary of the Invention

[0005] The purpose of this invention is to provide a delayed shutdown purging method for hydrogen fuel cell stack systems, addressing the problems in existing technologies where power outages during shutdown prevent effective purging, or where reliance on additional independent power supply modules for purging leads to system complexity, high cost, and inflexible control. Furthermore, incomplete purging (e.g., purging only the cathode) can result in problems such as residual water freezing and damage inside the stack, hydrogen accumulation safety hazards, membrane electrode carbon corrosion risks, and poor proton exchange membrane humidity management. The specific technical solution is as follows: This invention provides a delayed shutdown purging method for a hydrogen fuel cell stack system, comprising: S101, System power-on and self-locking maintenance: When the non-self-locking switch is triggered, the control contact group B closes to short-circuit the switch contact K_BAT, the system power supply bus is powered on, and after the main control chip MCU detects the power-on command, it controls the main relay to close to achieve power-on self-locking. The system performs self-test and starts the hydrogen fuel cell stack to generate electricity normally. S102. Power-off signal reception and purge start: During system operation, the MCU detects the power-off request triggered again by the non-locking switch, stops the fuel cell power generation, configures the purge air path and starts the blower, and starts the timer to set the total purge duration T. S103, Delayed Power Supply Purging Execution: During the total purging time T, the main control chip MCU maintains the main relay energized to keep the system continuously powered, and the blower continues to run to complete the fuel cell stack purging operation. S104. Purging Completed and System Power Off: When the timer reaches the total purging duration T, purging ends, the main control chip MCU closes the corresponding solenoid valve and cancels the main relay drive signal, disconnects the battery module output, and the system is completely powered off.

[0006] Furthermore, the purging method is applied to a hydrogen fuel cell stack system, which includes a battery module, a main control chip MCU, a non-locking switch, a main relay, a blower, and a hydrogen fuel cell stack. The non-locking switch includes a signal contact group and a control contact group, and the normally open contact of the main relay is connected in parallel with the control contact group.

[0007] Furthermore, the system also includes a cathode purging solenoid valve and an anode purging solenoid valve; both the cathode purging solenoid valve and the anode purging solenoid valve are two-position two-way solenoid valves, with their air inlets connected to the air outlet of the blower through pipelines, and their air outlets connected to the cathode air inlet and anode air inlet of the hydrogen fuel cell stack through pipelines, respectively, and controlled by the main control chip MCU through the corresponding drive circuit.

[0008] Furthermore, in step S102, the purge gas path configuration includes a combined purge configuration: the main control chip MCU controls the opening of the anode purge solenoid valve and the cathode purge solenoid valve, so that the blower's outlet gas path is simultaneously directed to the cathode and anode of the hydrogen fuel cell stack.

[0009] Furthermore, the cathode purging solenoid valve is a normally open solenoid valve, and the anode purging solenoid valve is a normally closed solenoid valve. The control of opening the anode purging solenoid valve and the cathode purging solenoid valve is specifically as follows: the main control chip MCU outputs an opening signal to the drive circuit that controls the anode purging solenoid valve, so that the normally closed anode purging solenoid valve is energized and switched to the open position, while keeping the cathode purging solenoid valve without a drive signal, and using its normally open characteristic to keep the cathode gas path open.

[0010] Further, in steps S102 and S103, the purging is time-division purging, including: First stage purging: The main control chip MCU controls the opening of the anode purging solenoid valve and controls the closing of the cathode purging solenoid valve, starts the blower to run, so that the gas path is only connected to the anode of the hydrogen fuel cell stack, and performs anode purging; Second stage purging: After the first stage purging is completed, the main control chip MCU controls the closure of the anode purging solenoid valve and controls the opening of the cathode purging solenoid valve to maintain the operation of the blower, so that the gas path is only connected to the cathode of the hydrogen fuel cell stack for cathode purging.

[0011] Furthermore, the duration of the first stage of purging is the first purging stage duration T1, the duration of the second stage of purging is the second purging stage duration T2, and the total purging duration T is equal to the sum of T1 and T2.

[0012] A hydrogen fuel cell stack system includes a master control chip (MCU) configured to perform the delayed shutdown purge method.

[0013] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, performs the steps of the method described herein.

[0014] A computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the steps of the method.

[0015] The beneficial effects of this invention are as follows: This invention, through a "software-enabled" delayed power-off mechanism based on non-locking switches and relay self-locking, cleverly utilizes the system's own battery to continuously power the comprehensive purging process after shutdown without relying on additional independent power supply modules (such as large capacitors or timed relays). This enables simultaneous or time-sharing combined purging of the stack's anode and cathode with flexible configuration. This not only thoroughly removes residual hydrogen and moisture, significantly improving the system's hydrogen safety and low-temperature antifreeze reliability, avoiding the risk of membrane electrode carbon corrosion, and optimizing the proton exchange membrane shutdown humidity, but the entire solution only requires the addition of a small number of conventional solenoid valves and relays. Complex and adaptive purging logic can be implemented through MCU software, and the system's main power supply is automatically cut off after purging is completed. This achieves a comprehensive advantage of flexible control, low cost, high reliability, and excellent user experience (one-button operation).

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of a hydrogen fuel cell stack system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of an existing hydrogen fuel cell stack system as described in the background section of this invention; Figure 3This is a schematic diagram of the steps of a delayed shutdown purging method for a hydrogen fuel cell stack system provided in an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1: This example provides a hydrogen fuel cell stack system capable of delayed shutdown purging, such as... Figure 1 As shown, the system includes a battery module, a main control chip MCU, a non-locking switch, a relay, a blower, a cathode purging solenoid valve (V_cathode), an anode purging solenoid valve (V_anode), and a hydrogen fuel cell stack (7). The non-locking switch includes a signal contact group A and a control contact group B; the normally open contact of the relay is connected in parallel with the contact group B of the switch; the battery module has its own switch contact (K_BAT); the blower's air outlet is connected to the cathode and anode of the fuel cell stack via solenoid valves. This diagram clearly shows the components required to achieve the delayed shutdown purging function and their connection relationships.

[0020] The battery module integrates a battery management system (BMS) with a pair of switch contacts K_BAT connected in series in the main output circuit of the battery, serving as the enable control terminal for battery output. When contact K_BAT is short-circuited by an external conductor, the BMS controls the battery to output its operating voltage (e.g., 12V or 24V) to the system power supply bus V_SYS; when contact K_BAT is open, the battery stops outputting power, and V_SYS is de-energized. The positive terminal of the battery module is connected to a circuit node P through the switch contacts K_BAT.

[0021] The non-locking switch is a mechanical push-button switch, comprising two independent sets of contacts: signal contact group A and control contact group B. One end of signal contact group A is connected to the system power supply bus V_SYS, and the other end is connected to a GPIO pin of the MCU with interrupt or level detection function (defined as a switch detection pin in this embodiment). Control contact group B is connected in series in the circuit of the switch contact K_BAT of the battery module, specifically, it is connected between the circuit node P and the system power supply bus V_SYS. When the non-locking switch is in the triggered state, contact groups A and B close synchronously; in the non-triggered state, they open synchronously.

[0022] The relay includes a coil and a normally open contact. One end of the coil is connected to the system power supply bus V_SYS, and the other end is connected to ground through a driver transistor Q1. The base of the transistor Q1 is connected to a GPIO pin of the MCU (defined as the relay control pin in this embodiment) through a current-limiting resistor R1. The MCU controls the transistor Q1 to turn on and off by controlling the output of a high or low level on this pin, thereby controlling the energization and de-energization of the relay K1 coil. The normally open contact of the relay is connected in parallel across the two ends of the control contact group B of the non-locking switch; that is, one end of the normally open contact is connected to circuit node P, and the other end is connected to the system power supply bus V_SYS.

[0023] The power input terminal of the blower is connected to the system power supply bus V_SYS, and its control terminal (such as the enable pin) is connected to another GPIO pin of the MCU (defined as the blower control pin in this embodiment). The MCU controls the start and stop of the blower by outputting a signal through this pin.

[0024] The cathode purge solenoid valve (V_cathode) is a two-position, two-way solenoid valve. Its inlet is connected to the outlet of the blower via a first pipe, and its outlet is connected to the cathode inlet of the fuel cell stack 7 via a second pipe. In this embodiment, V_cathode 5 is preferably normally open, meaning that when its coil is not energized, the valve core is in a position that connects the first and second pipes. Its coil is controlled by an MCU through a drive circuit.

[0025] The anode purge solenoid valve (V_anode) is a two-position, two-way solenoid valve. Its inlet is connected to the outlet of the blower via a third pipe, and its outlet is connected to the anode inlet of the fuel cell stack 7 via a fourth pipe. In this embodiment, V_anode 6 is preferably normally closed, meaning that when its coil is not energized, the valve core is in the position blocking the third and fourth pipes. Its coil is controlled by the MCU through a drive circuit.

[0026] The MCU is the control core of the entire system, and its power supply pin VCC and ground pin GND are connected to the system power supply bus V_SYS and ground, respectively.

[0027] Furthermore, a one-way valve to prevent gas backflow can be installed on the main pipeline between the air outlet of the blower and the air inlets of V_cathode 5 and V_anode 6. One-way valves can also be installed on the second and / or fourth pipelines.

[0028] The principle and effect of Embodiment 1 of this application are as follows: This embodiment provides a specific hardware system architecture. Its core principle lies in constructing an intelligent power supply circuit triggered by a non-self-locking switch and implemented by the MCU through the main relay for "self-locking" and "delayed shutdown". When the switch is triggered, the system is powered on and self-locked; when the switch is triggered again, the MCU does not immediately cut off the power, but continues to supply power to itself and the purging execution components (blower, solenoid valve) using the self-locked power supply circuit to execute the purging program; after purging is completed, the MCU actively cuts off the main relay, thereby physically disconnecting the battery output and achieving zero-power shutdown. This design creatively decouples the triggering operation from the system power-off, and uses the system's own battery to complete the shutdown maintenance function that originally required additional power supply. It solves the contradiction between "immediate power-off causing purging interruption" and "adding a power supply increases cost and complexity", ensuring the feasibility, automation and thoroughness of delayed purging at the hardware level.

[0029] Figure 1 This is a block diagram of a battery stack system or its power control section that lacks intelligent delayed shutdown and purging functionality and cannot be driven or managed by a power management system. The principle is as follows: After closing the main switch (SW), the battery directly powers the motor (possibly acting as a blower) and the DC / DC converter. The battery sends an enable (RND) signal to the motor and a power-on (RUP) signal to the DC / DC converter. Upon receiving power, the DC / DC converter powers the microcontroller unit (MCU) and sends a ready (RUP) signal, while also sending a RUP signal to the motor. The motor ultimately operates under the control of an external pulse-width modulation (PWM) signal. In this scheme, the motor (blower) drive power is directly taken from the battery bus without secondary conversion or isolation; fluctuations in the bus voltage may directly affect the stability and efficiency of motor operation. Simultaneously, the MCU's power supply relies entirely on the output of the front-end DC / DC converter, posing a risk of power failure to the entire control unit due to a single point of failure, thus requiring improved system robustness. Its control logic is relatively simple and does not reflect how to maintain power supply to complete subsequent complex timing control (such as joint purging of the anode and cathode of the fuel cell stack) after the main switch of the system triggers the "shutdown" intention. Compared with the intelligent, reliable and complete shutdown and purging solution based on "self-locking relay" and "MCU programmable delay shutdown" proposed in this application, it has obvious gaps in functionality, safety and intelligence.

[0030] Example 2: This example provides a delayed shutdown purge method applied to the system described in Example 1. This method is executed by the MCU, such as... Figure 3 As shown, the specific steps include: S101. System Power-On and Self-Locking Maintenance Steps: When the non-self-locking switch is triggered, its control contact group B closes, short-circuiting the switch contact K_BAT of the battery module. The battery module begins to output power, the system power supply bus V_SYS is powered on, and all power-consuming units such as the MCU and the relay K1 coil circuit are energized. At the same time, the signal contact group A of switch 3 closes, sending a high-level signal to the switch detection pin of the MCU.

[0031] After the MCU powers on and initializes, it immediately detects that this pin is high and determines it as a power-on command. The MCU then outputs a continuous high-level drive signal from its relay control pin, turning on the drive transistor Q1 and energizing the relay coil. The normally open contact of K1 closes, and this contact is connected in parallel with contact group B of switch 3. At this time, even if the non-locking switch resets (its contact group B opens), the switch contact K_BAT of the battery module remains short-circuited through the closed normally open contact of K1, and the system power supply is maintained. This process is called "power-on self-locking".

[0032] Subsequently, the MCU performs a system self-test and controls the start-up of the hydrogen fuel cell stack (7) to generate electricity normally. At this time, the anode purge solenoid valve (V_anode) (normally closed type) is in the closed position because it is not energized, blocking the gas path to the anode; the cathode purge solenoid valve (V_cathode) (normally open type) is in the open position because it is not energized, opening the gas path to the cathode; the blower does not work.

[0033] S102, Power-off signal reception and joint purge start-up steps: During system operation, when the non-locking switch is triggered again, its signal contact group A will close briefly again, thereby generating a low-to-high-to-low level change on the MCU's switch detection pin.

[0034] The MCU detects this signal change, determines it as a valid shutdown request, and immediately begins executing the shutdown purge sequence: a) Stop the fuel cell stack: The MCU sends a command to the fuel cell stack management system to perform standard safety shutdown operations, including closing the hydrogen supply valve, depressurizing, and disconnecting the main load contactor, so that the fuel cell stack 7 stops the chemical reaction.

[0035] b) Configure the combined purge air path: The MCU outputs an open signal (e.g., high level) to the drive circuit controlling the anode purge solenoid valve (V_anode), energizing the normally closed V_anode 6 to switch to the open position, thereby opening the air path to the anode. For the cathode purge solenoid valve (V_cathode), the MCU maintains its no-drive signal state, utilizing its normally open characteristic to keep the cathode air path open. At this time, the blower's outlet air path is simultaneously directed to the cathode and anode of the fuel cell stack 7.

[0036] c) Start purging and time the process: The MCU outputs a start signal to the blower control pin, starting the blower to run at a preset speed and begin delivering dry air to the anode and cathode. At the same time, an internal timer is started in the MCU to set the total purging duration T (e.g., T=60 seconds).

[0037] S103, Delayed Power Supply Purge Execution Steps: The purging operation continues within the timer's duration T. Dry air is simultaneously blown into the cathode and anode channels of the fuel cell stack, replacing residual hydrogen, oxygen, water vapor, etc.

[0038] Crucially, throughout the entire purging process, the MCU maintains a high-level output on its relay control pin, ensuring the relay remains energized. Therefore, the battery module's switch contact K_BAT is continuously shorted by the contact of K1, providing a stable power supply to the system power bus V_SYS, ensuring the continuous operation of all necessary loads, including the MCU itself, the blower, and the solenoid valve V_anode 6. This process is completely automatic, independent of the continuous triggering state of the switch, achieving "delayed power supply."

[0039] S104. Purge Completion and System Power-Off Procedure: The purging process ends when the MCU's internal timer reaches the preset total purging time T. The MCU then performs the following operations in sequence: First, the drive signal to the anode purge solenoid valve (V_anode) is removed, and V_anode 6 is de-energized and reset to the normally closed position, cutting off the anode gas path.

[0040] Next, the MCU cancels the drive signal to the relay, that is, sets the relay control pin to a low level. Transistor Q1 is then turned off, the relay coil is de-energized, and its normally open contact resets and opens.

[0041] At this moment, the control contact group B of the non-locking switch is in the open state, and the normally open contact of the relay is also open. The short-circuit circuit of the battery module's switch contact K_BAT is completely disconnected. The battery management system (BMS) detects the open circuit at the enable terminal and immediately stops the battery output. The voltage of the system power supply bus V_SYS drops to zero, and the MCU, blower, all solenoid valves, and other devices are instantly and completely powered off, and the entire system enters a completely shut-off state with no power consumption.

[0042] The principle and effect of Embodiment 2 of this application are as follows: This embodiment provides a specific control method based on the system of Embodiment 1. The principle is to convert the re-trigger signal of the switch into a shutdown trigger signal. After receiving this signal, the MCU initiates a preset timing logic including "stop power generation - start joint purging - delayed power supply execution - final power cut-off". The core effect of this method is to achieve "one-click" intelligent shutdown maintenance. After detecting the shutdown trigger signal, the system can automatically and completely execute the purging process and completely cut off the power after purging without human intervention. This method seamlessly integrates the necessary maintenance step of purging into the shutdown process. Utilizing the system's own energy and through sophisticated timing control, it completely solves the internal drying problem after the fuel cell stack is shut down without adding any operational burden, effectively preventing channel blockage and component corrosion, and significantly improving the system's reliability and lifespan.

[0043] Example 3: This example provides a time-sharing purging hydrogen fuel cell stack system and method. Based on the system architecture of Example 1, the purging strategy is optimized, a time-sharing purging mode is adopted, and it is also based on the "self-locking maintenance-delayed shutdown" mechanism.

[0044] The system configuration in this embodiment is basically the same as that in Embodiment 1, with the main difference being the control program logic pre-stored in the MCU. The cathode purge solenoid valve (V_cathode) in this embodiment can be either normally open or normally closed to achieve complete shut-off control of the cathode gas path. For clarity, this embodiment uses a normally closed cathode purge solenoid valve (V_cathode)′ as an example.

[0045] The delayed shutdown purging method in this embodiment has the same S101 system power-on and self-locking maintenance steps as embodiment 2, and the S104 purging completion and system power-off steps are logically consistent with S104 of embodiment 2. The core difference lies in the purging process executed after receiving the power-off signal, as follows: S202: The power-off signal reception and time-division purge start-up steps are as follows: After the MCU detects the shutdown request, it executes the shutdown purge sequence: a) Stop the fuel cell power generation: Same as Example 2 S102 a).

[0046] b) Initiate the first stage of purging (anode purging stage): The MCU outputs a control signal to energize and open the anode purge solenoid valve (V_anode) (normally closed type), thus connecting the anode gas path.

[0047] The MCU outputs a control signal to keep the cathode purge solenoid valve (V_cathode)′ (normally closed) de-energized and closed, blocking the cathode gas path. At this time, the gas path only leads to the anode of the fuel cell stack.

[0048] The MCU starts the blower.

[0049] The MCU starts the first timer and sets the duration of the first purge phase to T1 (e.g., T1 = 40 seconds).

[0050] c) First-stage purging execution and switching: During time T1, the system performs focused purging on the anode of the fuel cell stack to remove residual hydrogen. When the first timer expires, the MCU switches the purging mode.

[0051] d) Initiate the second stage of purging (cathode purging stage): The MCU cancels the drive signal to V_anode 6, causing it to lose power and shut down, thus blocking the anode gas path.

[0052] The MCU outputs a control signal to energize and turn on V_cathode 5′, thus connecting the cathode gas path.

[0053] The MCU maintains the operation of the blower (or adjusts its speed).

[0054] The MCU starts the second timer and sets the duration of the second purge phase to T2 (e.g., T2 = 20 seconds). The total purge time T = T1 + T2.

[0055] S203: Delayed Power Supply Time-Division Purge Execution Steps: Throughout the entire process from power-off until the end of the total time T, the MCU maintains the relay energized, and the battery continuously supplies power to the system. The MCU automatically controls the switching states of the two solenoid valves according to the preset timing sequence (T1, T2), realizing a time-division purging strategy of anode first, then cathode.

[0056] S204: Purging Completion and System Power-Off Procedure: When the total purging time T ends, the MCU first shuts down the blower and ensures that V_anode 6 and V_cathode 5′ are both off. Then, the MCU removes the drive signal to the relay, causing K1 to release, and finally disconnecting the battery module's switch contact K_BAT, achieving a complete system power-off.

[0057] The principle and effects of Embodiment 3 of this application are as follows: Based on the core hardware and basic processes of Embodiments 1 and 2, this embodiment provides an optimized purging strategy. The principle is that within a delayed power supply window guaranteed by a hardware self-locking circuit, the MCU executes programmable, phased purging timing control. By controlling the switching sequence of different solenoid valves, time-sharing and differentiated purging of the cathode and anode can be achieved. The beneficial effect of this embodiment is that it provides flexibility and optimization space for the purging strategy. For example, the anode can be purged first to quickly remove residual hydrogen and improve safety; then the cathode can be purged separately to fully dehumidify. This time-sharing strategy can more efficiently utilize limited purging time and energy, optimizing the treatment according to the different characteristics of residues at the anode and cathode. Therefore, under the same hardware foundation and delayed power supply mechanism, better purging effect and stack protection performance are obtained, demonstrating the scalability and superiority of the control logic of this invention.

[0058] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A delayed shutdown purging method for a hydrogen fuel cell stack system, characterized in that, include: S101, System power-on and self-locking maintenance: When the non-self-locking switch is triggered, the control contact group B closes to short-circuit the switch contact K_BAT, the system power supply bus is powered on, and after the main control chip MCU detects the power-on command, it controls the main relay to close to achieve power-on self-locking. The system performs self-test and starts the hydrogen fuel cell stack to generate electricity normally. S102. Power-off signal reception and purge start: During system operation, the MCU detects the power-off request triggered again by the non-locking switch, stops the fuel cell power generation, configures the purge air path and starts the blower, and starts the timer to set the total purge duration T. S103, Delayed Power Supply Purging Execution: During the total purging time T, the main control chip MCU maintains the main relay energized to keep the system continuously powered, and the blower continues to run to complete the fuel cell stack purging operation. S104. Purging Completed and System Power Off: When the timer reaches the total purging duration T, purging ends, the main control chip MCU closes the corresponding solenoid valve and cancels the main relay drive signal, disconnects the battery module output, and the system is completely powered off.

2. The method as described in claim 1, characterized in that, The purging method is applied to a hydrogen fuel cell stack system, which includes a battery module, a main control chip MCU, a non-locking switch, a main relay, a blower, and a hydrogen fuel cell stack. The non-locking switch includes a signal contact group and a control contact group, and the normally open contact of the main relay is connected in parallel with the control contact group.

3. The method as described in claim 2, characterized in that, The system also includes a cathode purging solenoid valve and an anode purging solenoid valve; both the cathode purging solenoid valve and the anode purging solenoid valve are two-position two-way solenoid valves, with their air inlets connected to the air outlet of the blower through pipelines, and their air outlets connected to the cathode air inlet and anode air inlet of the hydrogen fuel cell stack through pipelines, respectively, and controlled by the main control chip MCU through the corresponding drive circuit.

4. The method as described in claim 1, characterized in that, In step S102, the purge gas path configuration includes a combined purge configuration: the main control chip MCU controls the opening of the anode purge solenoid valve and the cathode purge solenoid valve, so that the blower's outlet gas path is simultaneously directed to the cathode and anode of the hydrogen fuel cell stack.

5. The method as described in claim 4, characterized in that, The cathode purging solenoid valve is a normally open solenoid valve, and the anode purging solenoid valve is a normally closed solenoid valve. The control of opening the anode purging solenoid valve and the cathode purging solenoid valve is as follows: the main control chip MCU outputs an opening signal to the drive circuit that controls the anode purging solenoid valve, so that the normally closed anode purging solenoid valve is energized and switched to the open position, while keeping the cathode purging solenoid valve without a drive signal, and using its normally open characteristic to keep the cathode gas path open.

6. The method as described in claim 1, characterized in that, In steps S102 and S103, the purging is time-division purging, including: First stage purging: The main control chip MCU controls the opening of the anode purging solenoid valve and controls the closing of the cathode purging solenoid valve, starts the blower to run, so that the gas path is only connected to the anode of the hydrogen fuel cell stack, and performs anode purging; Second stage purging: After the first stage purging is completed, the main control chip MCU controls the closure of the anode purging solenoid valve and controls the opening of the cathode purging solenoid valve to maintain the operation of the blower, so that the gas path is only connected to the cathode of the hydrogen fuel cell stack for cathode purging.

7. The method as described in claim 6, characterized in that, The duration of the first purging stage is T1, the duration of the second purging stage is T2, and the total purging duration T is equal to the sum of T1 and T2.

8. A hydrogen fuel cell stack system, characterized in that, include: The master control chip (MCU) is configured to perform the delayed shutdown purge method as described in any one of claims 1 to 7.

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