Fuel cell stack full state durability control method

Abstract

The application discloses a fuel cell stack full-state endurance control method, in which, in the fuel cell power-off state, a low-voltage power supply of a fuel cell controller is periodically automatically woken up by a whole vehicle full-state endurance monitoring system, and whether a hydrogen-oxygen interface exists in the fuel cell stack is synchronously monitored; if the hydrogen-oxygen interface exists, hydrogen pressure of the fuel cell stack anode is accurately controlled by the fuel cell controller, gas components in the cavity are quickly updated, and the hydrogen-oxygen interface in the fuel cell stack is eliminated; in the fuel cell stack start-up state, a long hydrogen discharge valve control mode is combined with a current load mode, so that the potential of single cell is quickly reduced, and the duration of the hydrogen-oxygen interface in the start-up state is shortened; in the fuel cell stack shutdown state, a hydrogen consumption oxygen control mode is adopted in the closed cathode cavity, oxygen in the fuel cell stack cathode cavity is completely consumed, nitrogen in the residual air and hydrogen of the anode are kept in pressure balance, and the hydrogen-oxygen interface is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fuel cell technology, and more particularly to a fuel cell stack full-state durability control method. BACKGROUND

[0002] A fuel cell system is a power generation device that generates electricity by electrochemical reaction of high-purity hydrogen and oxygen in air. The fuel cell system has the characteristics of high efficiency, zero emission, and short hydrogen refueling time, and is considered to be the most potential clean energy in the 21st century. It has been demonstrated, promoted and applied by the national and local governments.

[0003] When the hydrogen fuel cell vehicle is in short-term or long-term parking process, the poor sealing of the anode side of the fuel cell stack can easily cause negative pressure in the cavity, and air is sucked into the anode cavity and mixed with hydrogen. Or the air on the cathode side of the membrane electrode penetrates into the hydrogen cavity on the anode side under the action of gas permeation, which will cause the formation of a local hydrogen-oxygen interface in the anode cavity of the fuel cell stack. At the same time, when the vehicle is in normal operation process, if the fuel cell is in frequent start-stop, high-pressure emergency stop and other severe operating conditions, the gas cavity inside the fuel cell stack is easy to cause uneven pressure, and a local short-term hydrogen-oxygen interface can also be formed inside the fuel cell stack. If the fuel cell has a long-term hydrogen-oxygen interface, the carbon corrosion of the catalyst carrier inside the fuel cell stack will occur, and the catalyst particles will easily fall off and agglomerate from the carrier, reducing the effective catalytic activity, and ultimately reducing the durability and power generation performance of the fuel cell proton exchange membrane. SUMMARY

[0004] The present application provides a fuel cell stack full-state durability control method to solve the problem of long-term hydrogen-oxygen interface in fuel cells, reduce the durability and power generation performance of fuel cell proton exchange membranes, and other shortcomings.

[0005] The present application adopts the following technical solutions:

[0006] A fuel cell stack full-state durability control method based on a full-state durability monitoring system, the full-state durability monitoring system is composed of a battery management system BMS, a low-voltage power frequency converter DCL, a vehicle control unit VCU, a hydrogen management system HMS, a fuel cell controller FCU and a remote monitoring system TBOX, and communicates in real time through the vehicle CAN network, and shares the operation and diagnosis parameters of each unit; The control method is as follows:

[0007] S1, in the fuel cell power-off state, the low-voltage power supply of the fuel cell controller FCU is periodically automatically awakened by the full-state endurance monitoring system, and whether there is a hydrogen-oxygen interface inside the fuel cell stack is synchronously monitored, if there is, the fuel cell controller FCU is used to accurately control the hydrogen pressure of the fuel cell stack anode, the gas composition in the cavity is quickly updated, and the generation of the hydrogen-oxygen interface inside the fuel cell stack is eliminated;

[0008] S2, in the fuel cell stack open state, the control hydrogen exhaust valve long exhaust mode is combined with the current load mode, so that the potential of the single cell is quickly reduced, and the duration of the hydrogen-oxygen interface in the start-up state is shortened;

[0009] S3, in the fuel cell stack closed state, the control mode of consuming hydrogen gas to consume oxygen in the closed cathode cavity is adopted to ensure that the oxygen in the fuel cell stack cathode cavity is completely consumed, and the nitrogen in the remaining air and the hydrogen in the anode are kept in pressure balance.

[0010] Preferably, if the vehicle is in a power-off state, the low-voltage power supply inverter DCL is used for data monitoring after power-off; the low-voltage power supply inverter DCL converts high voltage to low voltage 24V through the high-voltage direct connection mode of the power battery, realizes the periodic automatic awakening function, outputs the low-voltage 24V power supply to awaken the vehicle controller VCU, and the vehicle controller VCU selectively awakens the hydrogen management system HMS, the fuel cell controller FCU, the remote monitoring system TBOX, and the battery management system BMS according to the power-off mode; the vehicle controller VCU acquires vehicle state information in real time, judges whether there is a hydrogen and electricity safety related fault in the vehicle, and transmits the hydrogen temperature and pressure, hydrogen concentration value, vehicle insulation value, fuel cell stack single highest voltage and lowest voltage, fuel cell stack hydrogen inlet and outlet pressure key information, and vehicle fault information to the enterprise monitoring platform through the vehicle remote monitoring system TBOX.

[0011] Preferably, the specific process of the above step S1 is as follows:

[0012] S11, judge whether the vehicle controller VCU receives the key signal from ACC to OFF gear, and the vehicle speed is 0, if yes, the vehicle is in a power-off state, and the vehicle is about to enter the eve of hibernation;

[0013] S12, the vehicle controller VCU sends the next start-up awakening time period to the low-voltage power supply inverter DCL through the CAN network, outputs the awakening power supply to drive the vehicle controller VCU to work, and calculates the next round of time interval according to the last stop hibernation time;

[0014] S13, when the low-voltage power converter DCL is dormant for 0.5 hours, the full-state endurance monitoring system awakens the vehicle control system to monitor whether the vehicle has any fault information, and the vehicle controller VCU drives and awakens the fuel cell controller FCU through the power relay to monitor whether there is a hydrogen-oxygen interface in the fuel cell stack;

[0015] S14, if the hydrogen outlet side pressure P12 is less than the set pressure threshold P15 for 3 seconds, the fuel cell controller FCU requests the vehicle controller VCU to provide high-pressure hydrogen gas source, and the fuel cell controller FCU controls the pressure of hydrogen out of the stack, wherein the hydrogen subsystem proportional valve opening degree adopts an adaptive PD control strategy;

[0016] S15, when hydrogen enters the fuel cell stack, the fuel cell controller FCU monitors the open-circuit voltage of the single cell in the fuel cell stack in real time, and if the open-circuit voltage U of the single cell is greater than the set safety voltage threshold U0 for 1 second, it indicates that there is a hydrogen-oxygen interface in the anode of the fuel cell stack, and enters S16;

[0017] S16, the fuel cell controller FCU controls the opening of the air subsystem bypass valve, operates the air compressor and the hydrogen circulating pump, and periodically opens the hydrogen exhaust valve and the water exhaust valve;

[0018] S17, if the hydrogen outlet side pressure P12 is greater than the set pressure threshold P15 for 3 seconds, there is no hydrogen-oxygen interface in the anode of the fuel cell stack, and the fuel cell controller FCU continues to monitor for 3 minutes, then enters the dormant state.

[0019] When the low-voltage power converter DCL is dormant for 1 hour, repeat steps S13 to S17; and so on to detect whether there is a hydrogen-oxygen interface in the fuel cell stack.

[0020] The adaptive PD control strategy for the hydrogen subsystem proportional valve opening degree in the above step S14 is as follows: the fuel cell stack hydrogen outlet side pressure P12 is taken as the hydrogen pressure control target P16, and satisfies 100kpa

[0021] The strategy of periodically opening the hydrogen discharge valve and the water discharge valve in step S16 is as follows: the opening time of the hydrogen discharge valve and the water discharge valve is set as t1 and t2 respectively, and , the control period of the entire exhaust valve and the water discharge valve is t0, and , the interval time t3 between the opening time of the hydrogen discharge valve and the water discharge valve is ; the opening time of the hydrogen discharge valve and the water discharge valve can also be adjusted according to the difference between the open circuit voltage U of the single cell and the set safety voltage threshold U0, for example, if the difference exceeds 0.1V, t1 and t2 are enlarged by 1 times, if the difference exceeds 0.2V, t1 and t2 are enlarged by 2 times, and so on, but still satisfying t1≤t2≤t0, so as to realize rapid updating of the gas composition in the anode cavity of the fuel cell stack, eliminate the hydrogen-oxygen interface, and realize the pure hydrogen state of the anode cavity.

[0022] Preferably, the specific process of step S2 is as follows:

[0023] S21, when the fuel cell controller FCU detects that the vehicle controller VCU sends an enable signal to start the stack, the fuel cell stack is in the start-up state, and the full-state durability monitoring system ensures that the entire fuel cell system is in a normal state after system self-checking, and then responds to the start-up request to open the cooling circulating water pump;

[0024] S22, the fuel cell controller FCU controls the hydrogen subsystem proportional valve, and simultaneously rapidly opens the hydrogen discharge valve and the water discharge valve of the hydrogen subsystem, which are in a normally open state within the entire control period t8, and then are closed for t4 seconds, and are in a normally open state again within the entire control period t8, so as to realize rapid updating of the anode gas of the fuel cell stack through two normally open states and one closed state.

[0025] S23, the hydrogen discharge valve and the water discharge valve enter a normal intermittent opening strategy, the opening period is t5, the opening time of the hydrogen discharge valve and the water discharge valve is t6 and t7 respectively, and t7≥t6, and then the air inlet valve of the stack is opened;

[0026] S24, it is judged whether the open circuit voltage U of the single cell is greater than the set safety voltage threshold U1 for 1 second, if yes, it indicates that the hydrogen-oxygen interface appears in the anode of the fuel cell stack, a pre-load is performed by using the boost frequency converter DCF, the load current is set as I0, and the load slope is set as K0, until the voltage U of the single cell is less than U2; if not, the hydrogen discharge pressure P12 of the fuel cell stack is controlled to meet the requirements.

[0027] Preferably, the specific process of step S3 is as follows:

[0028] S31, when the fuel cell controller FCU detects that the vehicle controller VCU sends the start-up enable signal, the fuel cell stack is in the shutdown state, the fuel cell controller FCU sends the power reduction instruction to the boost frequency converter DCF until the idle power P0 is reached;

[0029] S32, start the vehicle power-off state durability monitoring, increase the speed n of the air compressor, after the fuel cell stack cathode purging T seconds, close the air inlet stack solenoid valve, open the bypass solenoid valve, reduce the boost frequency converter DCF load power to the minimum value Pmin;

[0030] S33, when the single cell voltage U is less than the set threshold U3, stop the boost frequency converter DCF load.

[0031] Further, after the boost frequency converter DCF stops loading in step S33 described above, the stack still has a residual voltage U3, which is discharged by the air compressor coil winding, the vehicle high voltage input is cut off, the dependence on the internal discharge resistance of the boost frequency converter DCF is reduced, and the fuel cell stack is in a low potential.

[0032] From the above description of the present application, compared with the prior art, the present application has the following advantages:

[0033] The present application couples the whole vehicle and the parts into the control, based on the electrical architecture and control strategy of the whole vehicle, constructs the vehicle 24-hour "power-off-start-up-shutdown" full-state durability monitoring system, realizes the all-weather monitoring of the hydrogen-oxygen interface formation time which affects the durability of the fuel cell stack and takes different protection measures, aims to shorten the formation time of the hydrogen-oxygen interface, realizes the all-weather high-efficiency catalytic performance of the fuel cell, greatly improves the durability of the fuel cell stack for vehicle use, and thus improves the service life of the fuel cell stack from the source end. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The present application is a fuel cell system structure schematic diagram.

[0035] Figure 2 The present application is a fuel cell stack power-off state durability control flow chart.

[0036] Figure 3 The present application is a fuel cell stack start-up state durability control flow chart.

[0037] Figure 4 The present application is a fuel cell stack shutdown state durability control flow chart. DETAILED DESCRIPTION

[0038] The specific embodiments of the present application will be described with reference to the drawings. In order to fully understand the present application, numerous specific details are described below, but the present application can be implemented without these details. For well-known components, methods and processes, the following will not be described in detail.

[0039] Referring to Figure 1 The fuel cell system according to the present application is composed of a fuel cell stack, a hydrogen subsystem, an air subsystem, etc. The fuel cell stack is the core component of the entire system, and the remaining subsystems provide external conditions for the fuel cell stack to generate electricity.

[0040] The air subsystem includes an air compressor, an intercooler, an inlet valve, a humidifier, a back pressure valve, a bypass valve, and an exhaust pipe. The air compressor is connected to the intercooler, the intercooler is connected to the humidifier through the inlet valve, the humidifier is connected to the fuel cell stack, the outlet end of the humidifier is connected to the exhaust pipe through the back pressure valve, the outlet end of the intercooler is connected to the exhaust pipe through a bypass pipe, and the bypass pipe is provided with a bypass valve.

[0041] The hydrogen subsystem includes a high-pressure cylinder group, a main hydrogen valve, a proportional valve, a hydrogen circulation pump, an exhaust valve, a drain valve, and an exhaust pipe. The high-pressure cylinder group is connected to the fuel cell stack through the main hydrogen valve and the proportional valve in sequence, the outlet of the fuel cell stack is connected to a hydrogen circulation pump and an exhaust pipe through the exhaust valve and the drain valve, and the hydrogen circulation pump is connected to the connecting pipeline between the proportional valve and the fuel cell stack.

[0042] The fuel cell stack full-state durability control method according to the present application is based on a full-state durability monitoring system. The full-state durability monitoring system is composed of a battery management system BMS, a low-voltage power inverter DCL, a vehicle controller VCU, a hydrogen management system HMS, a fuel cell controller FCU, and a remote monitoring system TBOX, and communicates in real time through the vehicle CAN network, sharing the operation and diagnostic parameters of each unit.

[0043] If the vehicle is in a power-off state, the low-voltage power frequency converter DCL is used for data monitoring after power-off. The low-voltage power frequency converter DCL converts high voltage to low voltage 24V through high-voltage direct connection of the power battery, realizes periodic automatic wake-up function, outputs low-voltage 24V power to wake up the vehicle controller VCU, and the vehicle controller VCU selectively wakes up the hydrogen management system HMS, the fuel cell controller FCU, the remote monitoring system TBOX, the battery management system BMS and other control units according to the power-off mode. The vehicle controller VCU obtains the vehicle state information in real time, judges whether there is a hydrogen and electricity safety related fault in the vehicle, and transmits the key information such as hydrogen temperature and pressure, hydrogen concentration value, vehicle insulation value, single piece maximum voltage and minimum voltage of fuel cell stack, fuel cell stack hydrogen inlet and outlet pressure and vehicle fault information to the enterprise monitoring platform through the vehicle remote monitoring system TBOX.

[0044] Reference Figure 2 When the vehicle is in a power-off state, the fuel cell stack durability control step is as follows:

[0045] S11, when the vehicle controller VCU receives the key signal from ACC to OFF gear, and the vehicle speed is 0, it is judged that the vehicle is in a power-off state, and the vehicle is about to enter the pre-sleep state.

[0046] S12, the vehicle controller VCU sends the next start wake-up time period to the low-voltage power frequency converter DCL through the CAN network, and the DCL outputs the wake-up power to drive the vehicle controller VCU to work according to the time interval 0.5h, 1h, 2h, 4h, 8h, 8h... (after 8h), and calculates the next round of time interval according to the last stop sleep time.

[0047] The single data monitoring time of the self-wake-up mode is 10 minutes, the low-voltage power frequency converter DCL is started after the vehicle is powered on in the driving state, and the data monitoring is continued for 10 minutes.

[0048] S13, when the low-voltage power frequency converter DCL sleeps for 0.5 hours, the full-state durability monitoring system wakes up the vehicle electric control system to monitor whether there is fault information in the vehicle, and the vehicle controller VCU drives and wakes up the fuel cell controller FCU through the power relay to monitor whether there is a hydrogen-oxygen interface in the fuel cell stack.

[0049] The fuel cell control system FCU starts to perform system self-checking to ensure that the entire fuel cell system is in a normal state, the hydrogen pressure, air pressure, single cell voltage and hydrogen concentration are all in a normal range. Then the fuel cell controller FCU monitors the fuel cell stack hydrogen outlet side pressure P12.

[0050] S14, if the hydrogen outlet side pressure P12 continues to be less than the set pressure threshold P15 for 3 seconds, the fuel cell stack anode can have a hydrogen-oxygen interface risk. At this time, the fuel cell controller FCU requests the vehicle controller VCU to provide high pressure, and requests the vehicle to provide a high pressure hydrogen gas source. The vehicle controller VCU receives the request signal of the fuel cell controller FCU, and the vehicle key is in the off state, the vehicle has no fault, etc. The judgment signal closes the vehicle multi-HVCM relay, and a single channel provides a fuel cell high voltage, and the voltage range is 450-750V. At the same time, through the hydrogen management system HMS control bottle valve and main electromagnetic valve on the vehicle hydrogen system, ensure that the fuel cell system inlet hydrogen pressure is 10-15bar.

[0051] The pressure of the hydrogen gas out of the stack is controlled by the fuel cell controller FCU, wherein the hydrogen subsystem proportional valve opening degree adopts an adaptive PD control strategy, the fuel cell stack hydrogen outlet side pressure P12 is taken as the hydrogen pressure control target P16, and 100kpa

[0052] S15, when the hydrogen enters the fuel cell stack, the fuel cell control system FCU simultaneously monitors the open circuit voltage of the single cell in the fuel cell stack in real time (if the fuel cell system has a matching single cell voltage detection module, the highest voltage of the single cell is taken as the open circuit voltage U of the single cell; if there is no matching single cell voltage detection module, the total voltage of the fuel cell stack output is divided by the number of single cells to obtain the value as the open circuit voltage U). If the open circuit voltage U of the single cell continues to be greater than the set safety voltage threshold U0 for 1 second, it indicates that the fuel cell stack anode has a hydrogen-oxygen interface, and the fuel cell control system FCU immediately performs the next step operation; if the above voltage detection requirement is not met, it indicates that the fuel cell stack does not have a hydrogen-oxygen interface, and is ready to enter the sleep mode.

[0053] S16, in order to make full use of the air flow rate of the air compressor to dilute the tail hydrogen, reduce the concentration of the discharged hydrogen, and improve the safety of hydrogen discharge, the fuel cell control system FCU controls the bypass valve of the air subsystem, sets the opening degree to 90%, and controls the air compressor to run at the minimum speed N1min. When the difference between the actual speed of the air compressor and the target set speed is less than the set speed difference threshold, the hydrogen discharge valve, the water discharge valve, the hydrogen circulating pump, etc. of the hydrogen subsystem are quickly opened, wherein the set speed of the hydrogen circulating pump is at the highest operating speed N2max.

[0054] In order to improve the utilization rate of hydrogen and the safety of hydrogen discharge, the hydrogen discharge valve and the water discharge valve adopt an intermittent opening strategy. The opening times of the hydrogen discharge valve and the water discharge valve are set as t1 and t2 respectively, and , the control period of the entire exhaust valve and the water discharge valve is t0, and , the opening time interval t3 of the hydrogen discharge valve and the water discharge valve is . The opening times of the hydrogen discharge valve and the water discharge valve can also be adjusted according to the difference between the open circuit voltage U of the single cell and the set safety voltage threshold U0. For example, if the difference exceeds 0.1V, t1 and t2 are enlarged by 1 times; if the difference exceeds 0.2V, t1 and t2 are enlarged by 2 times; and so on, but still satisfy t1≤t2≤t0, so as to quickly update the gas composition in the anode cavity of the fuel cell stack, eliminate the hydrogen-oxygen interface, and realize the pure hydrogen state of the anode cavity.

[0055] S17, if the hydrogen outlet side pressure P12 continuously exceeds the set pressure threshold P15 for 3 seconds, there is no hydrogen-oxygen interface in the anode of the fuel cell stack, and the fuel cell control system FCU continuously monitors for 3 minutes, then enters the hibernation state.

[0056] When the low-voltage power supply frequency converter DCL hibernates for 1 hour, the steps S13 to S17 are repeated; and so on to detect whether there is a hydrogen-oxygen interface in the fuel cell stack during hibernation.

[0057] Referring to Figure 3 When the fuel cell stack is in the open state, the fuel cell stack durability control steps are as follows:

[0058] S21, when the fuel cell control system FCU detects that the vehicle controller VCU sends an open enable signal, the fuel cell stack is in the open state, and the full-state durability monitoring system ensures that the entire fuel cell system is in a normal state after system self-checking. The hydrogen pressure, air pressure, single cell voltage, hydrogen concentration, etc. are all in the normal range. Then, in response to the open request, the cooling circulating water pump is opened.

[0059] S22, the fuel cell control system FCU controls the hydrogen subsystem proportional valve, quickly establishes the fuel cell stack hydrogen out-of-stack pressure P12, and satisfies 140kpa < P12≤ 150kpa, simultaneously quickly opens the hydrogen exhaust valve and the water exhaust valve of the hydrogen subsystem, and the whole control period t8 is in the normally open state, then is closed for t4 seconds, and the whole control period t8 is in the normally open state again, and after two normally open and one closed states, the anode gas of the fuel cell stack is quickly renewed.

[0060] S23, the hydrogen exhaust valve and the water exhaust valve enter the normally intermittent opening strategy, the opening period t5, and the opening time of the hydrogen exhaust valve and the water exhaust valve is t6 and t7 respectively, and t7≥t6, and then the air inlet electromagnetic valve is opened;

[0061] S24, in the open stack state, the fuel cell control system FCU monitors the open circuit voltage U of the single cell in the fuel cell stack in real time (if the fuel cell system has a matched single cell voltage detection module, the highest voltage of the single cell is taken as the open circuit voltage U of the single cell; if there is no matched single cell voltage detection module, the total voltage of the fuel cell stack output is divided by the number of single cells to obtain the value as the open circuit voltage U). If the open circuit voltage U of the single cell is continuously greater than the set safety voltage threshold U1 for 1 second, it indicates that the hydrogen-oxygen interface appears in the anode of the fuel cell stack, at this time, the boost frequency converter DCF is used for pre-loading, the pre-loading current is set as I0, and the pre-loading slope is set as K0, until the single cell voltage U is less than U2, and the risk of high potential of the fuel cell stack is reduced; if the above voltage detection requirements are not met, it indicates that there is no hydrogen-oxygen interface in the fuel cell stack, until the fuel cell stack hydrogen out-of-stack pressure P12 satisfies 140kpa < P12≤ 150kpa.

[0062] Reference Figure 4 When the fuel cell stack is in the closed stack state, the fuel cell stack durability control steps are as follows:

[0063] S31, when the fuel cell control system FCU detects that the vehicle controller VCU sends a closed stack enable signal, the fuel cell stack is in the closed stack state, the fuel cell control system FCU sends a power load reduction instruction to the boost frequency converter DCF, until the idle power P0 is reached.

[0064] S32, the whole state durability monitoring system starts to intervene, the vehicle power-off state durability monitoring is started, the speed n of the air compressor is increased, after the fuel cell stack cathode is purged for T seconds, the air inlet electromagnetic valve is closed, the bypass electromagnetic valve is opened, and the boost frequency converter DCF load power is reduced to the minimum value Pmin.

[0065] S33, when the single cell voltage U is less than the set threshold U3, stop the boost frequency converter DCF to pull load, at this time the oxygen of the fuel cell stack cathode side is completely reacted with the hydrogen of the anode side, the cathode side is only the nitrogen in the air, etc., the necessary condition of realizing the state of closing the stack to clear the oxygen in the internal of the stack, hindering the hydrogen oxygen interface formation.

[0066] After the boost frequency converter DCF stops pulling load in the above step S33, the stack still has residual voltage U3, self-discharge is carried out through the air compressor coil winding, the high voltage input of the whole vehicle is cut off, the dependence on the internal discharge resistance of the boost frequency converter DCF is reduced, the fuel cell stack is in a low potential, and the durability of the fuel cell stack is improved.

[0067] The above is only a specific embodiment of the present application, but the design concept of the present application is not limited thereto, and any non-essential modification of the present application using this concept shall be deemed to be an act of infringing the protection scope of the present application.

Claims

1. A fuel cell stack full-state durability control method, characterized by: Based on the full-state durability monitoring system, the full-state durability monitoring system consists of a power battery management system BMS, a low-voltage power inverter DCL, a vehicle controller VCU, a hydrogen management system HMS, a fuel cell controller FCU and a remote monitoring system TBOX. It communicates in real time through the vehicle CAN network to share the operation and diagnostic parameters of each unit; if the vehicle is in a power-off state, the low-voltage power inverter DCL is used to monitor the data after power-off; the low-voltage power inverter DCL converts high-voltage frequency conversion to low-voltage 24V through a high-voltage direct connection to the power battery, realizing a periodic automatic wake-up function and outputting a low-voltage 2 The 4V power supply wakes up the vehicle controller VCU, which selectively wakes up the hydrogen management system HMS, fuel cell controller FCU, remote monitoring system TBOX, and battery management system BMS according to the power-off mode. The vehicle controller VCU obtains vehicle status information in real time to determine whether the vehicle has any hydrogen-electricity safety-related faults. It also transmits key information such as hydrogen temperature and pressure, hydrogen concentration, vehicle insulation value, maximum and minimum voltage of the fuel cell stack chip, hydrogen inlet and outlet pressure of the fuel cell stack, and vehicle fault information to the enterprise monitoring platform through the on-board remote monitoring system TBOX. The control method is as follows: S1. When the fuel cell is powered off, the full-state endurance monitoring system periodically and automatically wakes up the low-voltage power supply of the fuel cell controller FCU, and simultaneously monitors whether there is a hydrogen-oxygen interface inside the fuel cell stack. If so, the fuel cell controller FCU is used to accurately control the hydrogen pressure of the fuel cell stack anode, quickly update the gas composition in the cavity, and eliminate the generation of the hydrogen-oxygen interface inside the fuel cell stack; the specific process is as follows: S11. Determine whether the vehicle controller VCU receives the key signal to switch from ACC to OFF gear, and the vehicle speed is 0. If so, the vehicle is in a power-off state and is about to enter sleep mode; S12. The vehicle controller VCU sends the next start-up wake-up time period to the low-voltage power inverter DCL through the CAN network, outputs the wake-up power to drive the vehicle controller VCU to work, and calculates the next round of time intervals according to the last stop sleep time; S13. When the low-voltage power inverter DCL is dormant for 0.5 hours, the full-state endurance monitoring system automatically wakes up the on-board electronic control system to monitor whether there is any fault information in the vehicle. At the same time, the vehicle controller VCU drives and wakes up the fuel cell controller F CU, monitors whether there is a hydrogen-oxygen interface inside the fuel cell stack; S14, if the hydrogen outlet side pressure P12 is less than the set pressure threshold P15 for 3 seconds, the fuel cell controller FCU requests the vehicle controller VCU to increase the high pressure, and requests the vehicle controller VCU to provide a high-pressure hydrogen gas source. The fuel cell controller FCU controls the pressure of the hydrogen out of the stack, wherein the opening of the hydrogen subsystem proportional valve adopts an adaptive PD control strategy; S15, when hydrogen enters the fuel cell stack, the fuel cell controller FCU monitors the open circuit voltage of the single cell inside the fuel cell stack in real time. If the open circuit voltage U of the single cell is greater than the set safety voltage threshold U0 for 1 second, it indicates that there is a hydrogen-oxygen interface at the anode of the fuel cell stack, and enters S16; S16, the fuel cell controller FCU controls the bypass valve of the air subsystem to open, operates the air compressor and hydrogen circulation pump, and periodically opens the hydrogen drain valve and the water drain valve; S17, if the hydrogen outlet side pressure P12 is greater than the set pressure threshold P15 for 3 seconds, there is no hydrogen-oxygen interface at the anode of the fuel cell stack. The fuel cell controller FCU continues monitoring for 3 minutes and then enters the sleep state; S2. When the fuel cell stack is in the start-up state, a combination of controlling the long discharge of the hydrogen exhaust valve and current loading is adopted to quickly reduce the potential of the single cell and shorten the duration of the hydrogen-oxygen interface in the start-up state; S3. When the fuel cell stack is in the off state, a control method is adopted in which hydrogen consumes oxygen in the closed cathode cavity to ensure that the oxygen in the cathode cavity of the fuel cell stack is completely consumed, and the remaining nitrogen in the air maintains pressure balance with the hydrogen at the anode.

2. A fuel cell stack full-state durability control method according to claim 1, characterized in that: When the low-voltage power converter DCL is dormant for 1 hour, steps S13 to S17 are repeated; and the dormant intervals are used to detect whether there is a hydrogen-oxygen interface in the fuel cell stack.

3. The fuel cell stack full-state durability control method according to claim 1, characterized in that: The strategy for periodically opening the hydrogen discharge valve and the water discharge valve in step S16 is as follows: the opening times of the hydrogen discharge valve and the water discharge valve are set to t1 and t2 respectively, and The control period of the entire exhaust valve and drain valve is t0, and it satisfies , then the time interval t3 between the opening of the hydrogen discharge valve and the drain valve is ; or adjust the opening time of the hydrogen discharge valve and the water discharge valve according to the difference between the open circuit voltage U of the single cell and the set safety voltage threshold U0. If the difference exceeds 0.1V, t1 and t2 are magnified by 1 times; if the difference exceeds 0.2V, t1 and t2 are magnified by 2 times, and so on, but still satisfying t1≤t2≤t0, to achieve rapid update of the gas composition in the anode cavity of the fuel cell stack, eliminate the hydrogen-oxygen interface, and keep the anode cavity in a pure hydrogen state.

4. A fuel cell stack full-state durability control method according to claim 1, characterized in that: The specific process of step S2 is as follows: S21: When the fuel cell controller FCU detects that the vehicle controller VCU sends a stack start enable signal, the fuel cell stack is in the stack start state. After the full-state durability monitoring system performs a system self-check to ensure that the entire fuel cell system is in a normal state, it responds to the stack start request and turns on the cooling circulation water pump. S22, the fuel cell controller FCU controls the hydrogen subsystem proportional valve and simultaneously quickly opens the hydrogen drain valve and water drain valve of the hydrogen subsystem. The valves are kept in a normally open state during the entire control period t8, then closed for t4 seconds, and kept in a normally open state again during the entire control period t8. After two normally open states and one closed state, the anode gas of the fuel cell stack is quickly updated. S23: The hydrogen discharge valve and the water drain valve enter the normal intermittent opening strategy in turn, with an opening period of t5. The opening times of the hydrogen discharge valve and the water drain valve are t6 and t7 respectively, and t7 ≥ t6. Then, the air inlet solenoid valve is opened. S24. Determine whether the open-circuit voltage U of a single cell is continuously greater than the set safety voltage threshold U1 for 1 second. If so, it indicates that a hydrogen-oxygen interface appears at the anode of the fuel cell stack. Use the boost converter DCF for pre-loading, set the loading current to I0, and set the loading slope to K0, until the single cell voltage U is less than U2. If not, control the fuel cell stack hydrogen outlet pressure P12 to meet the requirements.

5. A fuel cell stack full-state durability control method according to claim 1, characterized in that: The specific process of step S3 is as follows: S31: When the fuel cell controller FCU detects that the vehicle controller VCU sends a stack enable signal, the fuel cell stack is in the stack off state, and the fuel cell controller FCU sends a power reduction command to the boost converter DCF until the idle power P0 is reached; S32: Enable vehicle power-off durability monitoring, increase the air compressor speed n, and after T seconds of fuel cell stack cathode purge, close the air inlet solenoid valve, open the bypass solenoid valve, and reduce the boost converter DCF load power to the minimum value Pmin. S33: When the cell voltage U is lower than the set threshold value U3, the DCF load of the boost converter is stopped.

6. A fuel cell stack full-state durability control method according to claim 5, characterized in that: After the boost converter DCF stops pulling the load in step S33, there is still a residual voltage U3 in the fuel cell stack, which self-discharges through the air compressor coil winding, cuts off the high-voltage input of the entire vehicle, reduces the dependence on the internal discharge resistor of the boost converter DCF, and ensures that the fuel cell stack is at a low potential.

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