Air cooling type methanol reforming fuel cell system control method

Abstract

The invention discloses an air cooling type methanol reforming fuel cell system control method which comprises the following steps: after a controller of an air cooling type methanol reforming fuel cell system is powered on, the controller automatically enters a self-inspection state to inspect electrical and communication faults of the system; when no fault is found, the controller jumps to a preheating starting state after receiving a starting instruction; when a fault is found, the controller receives a debugging instruction and then jumps to a debugging state for troubleshooting; when the controller is in the preheating starting state and the temperature of the subsystem component meets the target temperature, the controller automatically jumps to a power generation preparation state; when the controller is in the power generation preparation state, the heating mode of the combustion chamber is switched, and the controller jumps to the power generation state after receiving the power generation instruction; when the controller is in a power generation state, the controller controls the actuator component according to a load power demand to complete methanol reforming hydrogen production and power output of the fuel cell stack; and after the controller receives the shutdown instruction, the controller jumps to the shutdown state. The control method provided by the invention solves the problems of start preheating of the methanol reforming fuel cell system, pile inlet and outlet temperature control, pile temperature uniformity control and the like.

Description

Technical Field

[0001] The invention relates to the technical field of methanol reforming hydrogen production fuel cells, and in particular to a control method for an air-cooled methanol reforming fuel cell system. Background Art

[0002] Proton exchange membrane fuel cells are energy conversion devices that can directly convert the chemical energy generated by hydrogen and oxygen in the electrochemical reaction process into electrical energy and thermal energy. The most common fuel is hydrogen. Since hydrogen is a gas at room temperature, it is difficult to store and transport it through high-pressure or low-temperature liquid hydrogen storage. In addition, there are few hydrogen refueling stations and the cost of building stations is very high. It is difficult to build the entire hydrogen refueling infrastructure on a large scale in the short term. Methanol is regarded as an ideal hydrogen carrier among liquid fuels. It is a liquid at room temperature and pressure, and has a low cost and is easy to transport and store. In addition, the storage, filling, transportation technology of methanol and the construction of related infrastructure are also relatively mature. Methanol reforming hydrogen production has the advantages of high volume energy density and high H / C molar ratio. Compared with hydrogen storage fuel cells, methanol reforming hydrogen production fuel cells can be used immediately after production, and have many advantages.

[0003] During the start-up and power generation phase of the methanol reforming hydrogen fuel cell system, the stack and heat exchanger need to be preheated to a certain operating temperature. The existing method is to design a complex oil cooling system consisting of a heat transfer oil circuit, an oil pump, an electronic three-way valve, a radiator and an oil storage tank. However, the oil cooling system has the disadvantages of large size, long preheating time, poor low-temperature start-up performance, high auxiliary power consumption, and deterioration of the heat transfer oil due to water absorption. The air cooling system consisting of a fan, an intake valve, a three-way valve and a blower can be used as the thermal management medium of the fuel cell stack, greatly simplifying the system thermal management components, significantly reducing the system volume, and improving the system specific power. However, the air-cooled methanol reforming fuel cell system has higher requirements for the control method, and there is no mature control method in the prior art. However, the air-cooled methanol reforming fuel cell system has higher requirements for the control of the inlet and outlet temperature of the stack, the control of the temperature uniformity of the stack, the decoupling control of the air system, and the temperature reduction control during the shutdown phase. At present, there is no mature control method in the industry. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the air-cooled methanol reforming fuel cell system in the prior art in that the temperature control of the fuel cell inlet and outlet, the temperature uniformity control of the fuel cell stack, the air system decoupling control, and the temperature reduction control during the shutdown phase cannot meet the higher requirements.

[0005] In order to achieve the above object, the present invention provides an air-cooled methanol reforming fuel cell system control method, the control method comprising the following steps:

[0006] After the controller of the air-cooled methanol reforming fuel cell system is powered on, the controller automatically enters a self-checking state to check for electrical and communication faults in the system;

[0007] Step S1, when no fault is found, the controller jumps to the start-up preheating state after receiving the start-up instruction; when a fault is found, the controller jumps to the debugging state after receiving the debugging instruction to troubleshoot the fault;

[0008] Step S2, when the controller is in the startup preheating state, when the temperature of the subsystem components meets the target temperature, the controller automatically jumps to the power generation preparation state;

[0009] Step S3, when the controller is in a power generation preparation state, the heating mode of the combustion chamber is switched, and the controller jumps to a power generation state after receiving a power generation instruction;

[0010] Step S4, when the controller is in a power generation state, the controller controls the actuator components according to the load power demand to complete the methanol reforming hydrogen production and the power output of the fuel cell stack;

[0011] Step S5: When the controller receives the shutdown command, it jumps to the shutdown state.

[0012] Optionally, when the controller automatically enters the self-test state, the controller controls the switch valve, methanol pump, and fan to be turned off, the main relay and the heating rod relay are disconnected, and the three-way valve is controlled to the direct exhaust position.

[0013] Optionally, in step S2, the subsystem components include at least any one or more of a combustion chamber, a reforming chamber, an integrated heat exchanger, and a thermal management inlet of a fuel cell stack.

[0014] Optionally, in step S2, when the controller is in the startup preheating state, the controller controls the main relay to disconnect, controls the three-way valve to the position leading to the gas mixing chamber, and closes the loop to control the heating rod relay to heat the combustion chamber temperature to the target temperature of the catalytic combustion of methanol water vapor; the controller controls the first methanol pump and the first fan, and adjusts the methanol water solution flow and air flow in the startup preheating stage to control the heat release of the catalytic combustion and heat the temperature of the combustion chamber to the target temperature; the heat released by the catalytic combustion is respectively transferred to the reforming chamber and the integrated heat exchanger to heat the reforming chamber and the integrated heat exchanger; the controller controls the air intake valve to open, and closes the loop to control the speed of the fan according to the target temperature of the thermal management inlet of the fuel cell stack; when the temperatures of the combustion chamber, reforming chamber, integrated heat exchanger, and thermal management inlet of the fuel cell stack meet the preset temperatures, the controller automatically jumps to the power generation preparation state.

[0015] Optionally, the target temperature of the methanol water vapor catalytic combustion is 200°C to 250°C, the target temperature of the combustion chamber is 450°C to 500°C, and the target temperature of the stack thermal management inlet is 130°C to 150°C.

[0016] Optionally, in step S4, when the controller is in the power generation state, the controller controls the main relay to close, disconnects the heating rod relay, and turns off the first methanol pump; the controller adjusts the methanol aqueous solution flow and the air flow according to the thermal power demand by controlling the duty cycle of the second methanol pump and the speed of the first fan, and heats the combustion chamber temperature to the target temperature of 450°C to 500°C by controlling the combustion of the hydrogen-rich gas in the combustion chamber; the controller controls the hydrogen-rich gas and air flow entering the fuel cell stack according to the load power demand by controlling the duty cycle of the second methanol pump and the speed of the second fan to meet the load power demand; the controller controls the intake valve to open, the three-way valve is in the position leading to the gas mixing chamber, and the fan speed is closed-loop controlled according to the target temperature of 130°C to 150°C at the thermal management outlet of the fuel cell stack.

[0017] Optionally, in step S5, when the controller is in the shutdown state, the controller controls the main relay to close, disconnects the heating rod relay, turns off the first methanol pump and the second methanol pump, and the three-way valve is in the direct exhaust position; the controller controls the speed of the first fan and the second fan in a closed loop according to the cooling targets of the combustion chamber, the reforming chamber and the integrated heat exchanger.

[0018] Optionally, in step S5, when the controller is in the shutdown state, the controller controls the intake valve to open, and according to the target temperature of 45°C at the thermal management inlet of the fuel cell stack, closes the fan speed control. After the temperature is reached, the controller controls the intake valve and the fan to close.

[0019] Compared with the prior art, the beneficial effects of the present invention include at least:

[0020] (1) During the startup and low-power power generation control stages of the air-cooled methanol reforming fuel cell system of the present invention, the controller performs closed-loop control of the air system fan, three-way valve, intake valve and other actuators, and introduces the combustion exhaust gas into the fuel cell stack as needed to heat the fuel cell stack, thereby realizing the reuse of waste heat and improving energy utilization.

[0021] (2) During the startup preheating control stage, the air-cooled methanol reforming fuel cell system of the present invention directly preheats the fuel cell stack by controlling the mixing ratio of the combustion exhaust gas and air, thereby accelerating the preheating speed of the fuel cell stack and shortening the startup time of the system.

[0022] (3) During the high-power power generation stage of the air-cooled methanol reforming fuel cell system of the present invention, high-temperature exhaust gas is introduced to heat the stack cooling medium on the basis of closed-loop control of the fuel cell stack inlet temperature, thereby effectively alleviating the problem of poor temperature uniformity of the high-temperature air-cooled stack and improving the power generation performance and operational reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the air-cooled methanol reforming fuel cell system of the present invention.

[0024] Figure 2 This is a flow chart of the air-cooled methanol reforming fuel cell system control method of the present invention.

[0025] Figure 3 FIG. 4 is a simplified diagram of the software control architecture of the present invention.

[0026] Figure identification: 1-combustion chamber, 2-reforming chamber, 3-integrated heat exchanger, 3-1-hydrogen-rich gas layer, 3-2-methanol solution layer, 3-3-combustion exhaust gas layer, 3-4-air layer, 4-fuel cell stack, 4-1-anode inlet, 4-2-anode outlet, 4-3-cathode inlet, 4-4-cathode outlet, 4-5-thermal management inlet, 4-6-thermal management outlet, 5-first methanol pump, 6-first fan, 7-three-way valve, 7-1-three-way valve inlet, 7-2-three-way valve first outlet, 7-3-three-way valve second outlet, 8-second methanol pump, 9-second fan, 10-gas mixing chamber, 10-1-gas mixing chamber first inlet, 10-2-gas mixing chamber second inlet, 11-intake valve, 12-fan. In the figure, the solid line (A) is the direction of the thermal management medium, the long dashed line (B) is the direction of the methanol solution, the short dashed line (C) is the direction of the anode fluid, and the dotted line (D) is the direction of the cathode fluid. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0028] like Figures 1 to 3 As shown, the present invention provides an air-cooled methanol reforming fuel cell system control method, the control method comprising the following steps:

[0029] After the controller of the air-cooled methanol reforming fuel cell system is powered on, the controller automatically enters a self-checking state to check for electrical and communication faults in the system;

[0030] Step S1, when no fault is found, the controller jumps to the start-up preheating state after receiving the start-up instruction; when a fault is found, the controller jumps to the debugging state after receiving the debugging instruction to troubleshoot the fault.

[0031] In the self-check state, the controller will control all switch valves, methanol pumps, fans and main relays to close, and the three-way valve 7 will be controlled to be in the fully open position of the second outlet 7-3 of the three-way valve. Furthermore, the controller will check the system electrical and communication faults according to the reference voltage threshold preset in the self-check state. If a fault is found in the self-check state, the system will stay in the self-check state and light up the fault code of the host computer, prompting the operator to check the electrical and communication faults; when the controller receives the debugging command, the system will jump to the debugging state, and the operator can check the electrical faults in the debugging state; if no fault is found in the self-check state, the controller will jump to the start-up preheating state after receiving the start command.

[0032] Step S2, when the controller is in the startup preheating state, when the temperature of the subsystem components meets the target temperature, the controller automatically jumps to the power generation preparation state.

[0033] When the controller jumps to the start-up preheating state, the controller will control the main relay to close, and the three-way valve 7 will be controlled to be in the fully open position of the first outlet 7-2 of the three-way valve; the controller will first control the heating of the electric heating wire in the combustion chamber 1 in a closed loop, and after the temperature of the combustion chamber 1 is heated to 200℃-250℃ to meet the temperature required for the catalytic combustion of methanol water vapor, the controller will automatically close the heating relay of the electric heating wire in the combustion chamber 1; then, the controller will control the operation of the first methanol pump 5 and the first fan 6 to transport the methanol aqueous solution and air to the combustion chamber 1 for catalytic combustion reaction respectively, and the target control temperature of the catalytic combustion of the combustion chamber 1 is 450℃-500℃; the controller will query the pre-calibrated duty cycle pulse spectrum and target air-fuel ratio pulse spectrum of the first methanol pump 5 according to the difference between the current combustion chamber 1 temperature and the target temperature, and control the opening of the first methanol pump 5 and the speed of the first fan 6; When the temperature of the combustion chamber 1 reaches the target temperature of 450℃-500℃, part of the heat released by the catalytic combustion in the combustion chamber 1 is transferred to the reforming chamber 2 to preheat it to the temperature of 200℃-250℃ required for the methanol steam reforming reaction, and the other part is taken away by the combustion exhaust gas and flows through the combustion exhaust gas layer 3-3 of the integrated heat exchanger 3 to preheat the integrated heat exchanger 3 to the evaporation temperature of the methanol solution 180℃-220℃; the combustion exhaust gas flowing through the integrated heat exchanger 3 enters the gas mixing chamber 10 after passing through the three-way valve 7; the controller controls the air intake valve 11 to open, and controls the speed of the fan 12 in a closed loop according to the target temperature of 130℃-150℃ of the thermal management inlet 4-5 of the fuel cell stack; when the temperature of the combustion chamber 1, the temperature of the reforming chamber 2, the temperature of the integrated heat exchanger 3 and the temperature of the thermal management inlet 4-5 all reach the target temperature, the start-up preheating phase is completed, and the controller will automatically jump to the power generation preparation state.

[0034] Step S3, when the controller is in the power generation preparation state, the heating method of the combustion chamber is switched, and the controller jumps to the power generation state after receiving the power generation instruction.

[0035] When the controller jumps to the power generation preparation state, the controller will control the main relay to disconnect and the first methanol pump 5 to close, and calculate the hydrogen flow rate required for combustion in the range of 450℃-500℃ according to the controller heat balance control module; the heat release of hydrogen and air in the combustion chamber 1 will replace the catalytic combustion heat release of the methanol solution delivered by the first methanol pump 5 in the startup preheating stage; the controller will calculate the methanol reforming flow rate in the power generation preparation stage according to the target hydrogen flow rate, and then control the duty cycle of the second methanol pump 8; at the same time, the controller will calculate the air flow rate required for hydrogen combustion in the power generation preparation stage according to the target hydrogen-air ratio pulse spectrum, and use this to control the speed of the first fan 6 in a closed loop; the second methanol pump 8 delivers the methanol reforming solution in the power generation preparation stage to the integrated heat exchanger 3, and after evaporation in the methanol solution layer 3-2, it enters the reforming chamber 2 for methanol water vapor reforming reaction, and the hydrogen-rich gas generated by the reaction enters the integrated heat exchanger 3, and enters the anode inlet 4-1 of the fuel cell after cooling in the hydrogen-rich gas layer 3-1; After the battery stack 4 is discharged, it enters the combustion chamber 1 and mixes with the air transported by the first fan 6 to burn and release heat, heating the combustion chamber 1 to the target temperature of 450℃-500℃; part of the heat released is transferred to the reforming chamber 2, preheating it to 200℃-250℃ to meet the requirements of the methanol steam reforming reaction, and the other part of the heat is taken away by the combustion tail gas, flows through the integrated heat exchanger 3 combustion tail gas layer 3-3 to preheat the integrated heat exchanger 3 to the evaporation temperature of the methanol solution 180℃-220℃, and then enters the three-way valve 7; The controller will control the air intake valve 11 to open, and the three-way valve 7 to be in the fully open position of the second outlet 7-3 of the three-way valve. According to the target temperature of the thermal management inlet (130℃-150℃), the speed of the fan 12 is closed-loop controlled, and the combustion exhaust gas and air are mixed in the gas mixing chamber 10 to heat and keep the fuel cell stack 4 warm; when the temperature of the combustion chamber 1, the temperature of the reforming chamber 2, the temperature of the thermal management inlet 4-5 and the temperature of the integrated heat exchanger 3 meet the above target temperatures at the same time, the controller will automatically jump to the power generation state.

[0036] Step S4, when the controller is in the power generation state, the controller controls the actuator components according to the load power demand to complete the methanol reforming hydrogen production and the power output of the fuel cell stack.

[0037] When the controller jumps to the power generation state, the controller controls the main relay to close, the first methanol pump 5 to close, and queries the methanol reforming flow rate according to the target hydrogen gas spectrum according to the load power, thereby controlling the duty cycle of the second methanol pump 8 in a closed loop; the second methanol pump 8 delivers methanol solution to the integrated heat exchanger 3, and after evaporation of the methanol solution layer 3-2, it enters the reforming chamber 2 for methanol steam reforming reaction, and the hydrogen-rich gas generated by the reaction enters the integrated heat exchanger 3, and enters the anode inlet 4-1 of the fuel cell stack after cooling the hydrogen-rich gas layer 3-1; at the same time, the controller The target load power is calculated according to the target air excess ratio map, and the speed of the second fan 9 is controlled in a closed loop; the second fan 9 delivers air to the integrated heat exchanger 3, and enters the cathode inlet 4-3 of the fuel cell stack after being preheated by the air layer 3-4; next, the controller will calculate the remaining hydrogen flow entering the combustion chamber 1 based on the target load power, and then calculate the air volume requirement of the combustion chamber 1 according to the target hydrogen-air excess coefficient map, and then control the speed of the first fan 6 in a closed loop; the controller will control the hydrogen flow entering the combustion chamber 1 and the speed of the first fan 6 in a closed loop. 6, the temperature of the combustion chamber 1 is controlled at 450℃-500℃; part of the released heat is transferred to the reforming chamber 2 for methanol steam reforming reaction, and the other part of the heat is taken away by the combustion tail gas, flows through the integrated heat exchanger 3 combustion tail gas layer 3-3 to preheat the integrated heat exchanger 3 to the evaporation temperature of the methanol solution 180℃-220℃, and then enters the three-way valve 7; the controller controls the intake valve 11 to be in the open state, and the three-way valve 7 is controlled to be in the fully open position of the first outlet 7-2 of the three-way valve, so as to achieve the target temperature of 130℃-150℃ at the thermal management outlet 4-6. , closed-loop control of the speed of the fan 12; the controller of the present invention controls the mixed gas in the gas mixing chamber 10 to heat the fuel cell stack 4 under low-power conditions, and controls the mixed gas in the gas mixing chamber 10 to dissipate heat for the fuel cell stack 4 under high-power conditions; under this control strategy, since the three-way valve 7 delivers high-temperature exhaust gas to the gas mixing chamber 10 in real time, under the condition that the thermal management outlet reaches the target temperature, the mixed gas at the thermal management inlet 4-5 can maintain a relatively high temperature, which effectively alleviates the problem of poor temperature uniformity of the high-temperature air-cooled stack and improves the power generation performance and operational reliability of the system.

[0038] Step S5: When the controller receives the shutdown command, it jumps to the shutdown state.

[0039] When the controller receives the shutdown command, the system will jump to the shutdown state and execute the shutdown process. The controller will control the main relay to disconnect, the first methanol pump 5 to turn off, the second methanol pump 8 to turn off, and the three-way valve 7 to control the second outlet 7-3 of the three-way valve to be fully open; the first fan 6 and the second fan 9 speeds are closed-loop controlled at a 50% duty cycle to cool the combustion chamber 1, the reforming chamber 2 and the integrated heat exchanger 3 respectively; when the temperatures of the three are all below 50°C, the controller will automatically control the first fan 6 and the second fan 9 to turn off; in this process, the controller controls the intake valve 11 to open, and the speed of the fan 12 is closed-loop controlled with the target temperature of 45°C at the outlet 4-6 of the stack thermal management. When the temperature of the thermal management outlet 4-6 is less than 50°C, the intake valve 11 and the fan 12 are closed.

[0040] During the startup preheating, power generation preparation, power generation and shutdown states, the fault diagnosis system diagnoses the system fault condition in real time and issues graded warnings for the faults. For high-level faults involving operator and system safety, the controller will automatically jump to the fault state and execute corresponding fault measures: the main relay is disconnected, the heating relay is turned off, the first methanol pump 5 is turned off, and the second methanol pump 8 is turned off; the controller outputs a 50% duty cycle to control the fan 12, the first fan 6 and the second fan 9 to operate; the three-way valve is controlled to be in the fully open position of the second outlet 7-3 of the three-way valve, and the air intake valve 11 is controlled to be open.

[0041] In summary, the present invention provides an air-cooled methanol reforming fuel cell system control method, which automatically enters a self-check state after the controller is powered on to check the system electrical and communication faults; if no fault is found, the controller will jump to the start-up preheating state after receiving a start-up command; if a fault is found, when the controller receives a debugging command, it will jump to the debugging state for troubleshooting; in the start-up preheating state, the controller automatically jumps to the power generation preparation state when the temperature of the subsystem components meets the target temperature; in the power generation preparation state, the controller mainly switches and controls the combustion chamber heating mode, and jumps to the power generation state when the controller receives a power generation command; in the power generation state, the controller will control actuators such as the methanol pump, the fan and the three-way valve according to the load power demand to complete methanol reforming hydrogen production and fuel cell stack power output; when the controller receives a shutdown command, it will control the main relay to disconnect and turn off the methanol pump, and cool the system by controlling the fan, fan speed and the three-way valve opening; the fault diagnosis module diagnoses system faults in real time, implements graded warnings for faults and executes corresponding fault measures. The control method solves the problems of start-up preheating of a methanol reforming fuel cell system, control of inlet and outlet temperatures of a fuel cell stack, and control of temperature uniformity of a fuel cell stack.

[0042] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A control method for an air-cooled methanol reforming fuel cell system, characterized in that: The control method comprises the following steps: After the controller of the air-cooled methanol reforming fuel cell system is powered on, the controller automatically enters a self-checking state to check for electrical and communication faults in the system; Step S1, when no fault is found, the controller jumps to the start-up preheating state after receiving the start-up instruction; When a fault is found, the controller jumps to the debugging state to perform fault troubleshooting after receiving the debugging instruction; Step S2, when the controller is in the startup preheating state, when the temperature of the subsystem components meets the target temperature, the controller automatically jumps to the power generation preparation state; Step S3, when the controller is in a power generation preparation state, the heating mode of the combustion chamber is switched, and the controller jumps to a power generation state after receiving a power generation instruction; Step S4, when the controller is in a power generation state, the controller controls the actuator components according to the load power demand to complete the methanol reforming hydrogen production and the power output of the fuel cell stack; Step S5: When the controller receives the shutdown command, it jumps to the shutdown state.

2. The air-cooled methanol reforming fuel cell system control method according to claim 1, characterized in that: When the controller automatically enters the self-check state, the controller controls the switch valve, methanol pump, and fan to be turned off, the main relay and the heating rod relay are disconnected, and the three-way valve is controlled to the direct exhaust position.

3. The air-cooled methanol reforming fuel cell system control method according to claim 1, characterized in that: In step S2, the subsystem components include at least any one or more of a combustion chamber, a reforming chamber, an integrated heat exchanger, and a thermal management inlet of a fuel cell stack.

4. The air-cooled methanol reforming fuel cell system control method according to claim 1, characterized in that: In step S2, when the controller is in the startup preheating state, the controller controls the main relay to disconnect, controls the three-way valve to the position leading to the gas mixing chamber, and closes the loop to control the heating rod relay to heat the combustion chamber temperature to the target temperature of the catalytic combustion of methanol water vapor; the controller controls the first methanol pump and the first fan, and adjusts the methanol water solution flow and the air flow in the startup preheating stage to control the heat release of the catalytic combustion and heat the temperature of the combustion chamber to the target temperature; the heat released by the catalytic combustion is respectively transferred to the reforming chamber and the integrated heat exchanger to heat the reforming chamber and the integrated heat exchanger; the controller controls the air intake valve to open, and controls the speed of the fan in a closed loop according to the target temperature of the thermal management inlet of the fuel cell stack; when the temperatures of the combustion chamber, the reforming chamber, the integrated heat exchanger, and the thermal management inlet of the fuel cell stack meet the preset temperatures, the controller automatically jumps to the power generation preparation state.

5. The air-cooled methanol reforming fuel cell system control method according to claim 4, characterized in that: The target temperature of the methanol water vapor catalytic combustion is 200°C to 250°C, the target temperature of the combustion chamber is 450°C to 500°C, and the target temperature of the stack thermal management inlet is 130°C to 150°C.

6. The air-cooled methanol reforming fuel cell system control method according to claim 1, characterized in that: In step S4, when the controller is in the power generation state, the controller controls the main relay to close, disconnects the heating rod relay, and turns off the first methanol pump; the controller adjusts the methanol water solution flow and the air flow according to the thermal power demand by controlling the duty cycle of the second methanol pump and the speed of the first fan, and heats the combustion chamber temperature to the target temperature of 450°C to 500°C by controlling the combustion of the hydrogen-rich gas in the combustion chamber; the controller controls the hydrogen-rich gas and air flow entering the fuel cell stack according to the load power demand by controlling the duty cycle of the second methanol pump and the speed of the second fan to meet the load power demand; the controller controls the intake valve to open, the three-way valve is in the position leading to the gas mixing chamber, and the fan speed is closed-loop controlled according to the target temperature of 130°C to 150°C at the thermal management outlet of the fuel cell stack.

7. The air-cooled methanol reforming fuel cell system control method according to claim 1, characterized in that: In step S5, when the controller is in the shutdown state, the controller controls the main relay to close, disconnects the heating rod relay, turns off the first methanol pump and the second methanol pump, and the three-way valve is in the direct exhaust position; the controller controls the speed of the first fan and the second fan in a closed loop according to the cooling targets of the combustion chamber, the reforming chamber and the integrated heat exchanger.

8. The air-cooled methanol reforming fuel cell system control method according to claim 1, characterized in that: In step S5, when the controller is in the shutdown state, the controller controls the intake valve to open, and according to the target temperature of 45°C at the thermal management inlet of the fuel cell stack, the fan speed is controlled to close. After the temperature is reached, the controller controls the intake valve and the fan to close.

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