A method and system for starting a fuel cell

Abstract

The application relates to the technical field of fuel cells, and discloses a starting method and system of a fuel cell; when a driver issues a starting instruction, corresponding parts are started; a controller calculates the opening time T required by a hydrogen discharge valve; hydrogen is introduced into a hydrogen storage tank until the pressure reaches a target replacement pressure, then the hydrogen discharge valve is started until the opening time T is reached, the hydrogen discharge valve is closed after hydrogen replacement is completed, air is introduced into the hydrogen storage tank, and the fuel cell is started. According to the method, the opening time required by the hydrogen discharge valve during starting of the fuel cell is calculated according to different conditions, the hydrogen replacement time is accurately controlled, hydrogen waste is avoided, the replacement time is shortened, and the starting speed of the fuel cell is improved.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and more specifically to a fuel cell start-up method and system. Background Technology

[0002] The basic working principle of a fuel cell is that hydrogen and oxygen undergo an electrochemical reaction in the presence of a catalyst, converting chemical energy into electrical energy. The oxygen comes from the air, and the hydrogen comes from a hydrogen storage system. Fuel cells often have high requirements for the quality of the hydrogen supplied. If the hydrogen supplied to the fuel cell contains harmful gases, it can poison the fuel cell catalyst, causing performance degradation. If the purity of the reacting gases on the hydrogen side is insufficient, it can cause localized hydrogen deficiency in the fuel cell, leading to corrosion of the carbon support of the catalyst and also causing performance degradation. Therefore, during the startup phase of a fuel cell system, pure hydrogen is used first to fully replace impurities on the anode side (hydrogen side). Once the hydrogen concentration on the anode side meets the requirements, current is applied to prevent rapid performance degradation of the fuel cell stack.

[0003] During the startup phase of existing fuel cells, in order to fully replace the impurity gases on the anode side, the opening time and replacement pressure of the hydrogen venting valve are calibrated. First, a fixed replacement pressure P is set, and the hydrogen supply device is controlled to supply hydrogen to the stack at pressure P. Then, the venting valve is controlled to open / close according to a set opening cycle and opening time. Next, the hydrogen concentration on the anode side is monitored in real time by a hydrogen concentration sensor. When the concentration reaches the target value, the current replacement pressure and the opening time and cycle of the venting valve are recorded, which constitutes the hydrogen replacement strategy for startup. However, this method has the following problems:

[0004] 1. The existing method is to perform the replacement under the most stringent conditions. The hydrogen concentration on the anode side is different in different scenarios. If all the most stringent conditions are followed, it will result in the waste of hydrogen.

[0005] 2. In order to ensure that the concentration of hydrogen emitted during the replacement process meets the standard, an air compressor is required to provide air for dilution. When the air compressor is insufficient, the replacement speed needs to be limited and the start-up time of the fuel cell needs to be increased. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention proposes a fuel cell startup method and system that can adjust the replacement strategy in real time according to different scenarios.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A method for starting a fuel cell includes the following steps:

[0009] S1: In standby mode, the driver issues a start command, and all components are powered on;

[0010] S2: The controller calculates the required opening time T of the hydrogen discharge valve;

[0011] S3: Turn on the hydrogen supply equipment to introduce hydrogen into the fuel cell stack until the pressure reaches the target replacement pressure P. _tar And maintain this pressure; proceed to the next step if the air compressor and hydrogen circulation unit start successfully, otherwise continue to wait for them to start successfully;

[0012] S4: Start the hydrogen venting valve and close it when the opening time of the hydrogen venting valve reaches T.

[0013] S5: Air intake is complete, and the engine enters operating mode.

[0014] Furthermore, step S1 also includes: setting the bypass valve to the fully open state and starting the air compressor, water pump and hydrogen circulation device.

[0015] Furthermore, step S2 specifically includes:

[0016] S201: Calculate the downtime Δt of the fuel cell system;

[0017] S202: Estimate the hydrogen concentration C1 on the anode side of the fuel cell stack based on the downtime Δt, and obtain the hydrogen pressure P1 on the anode side and the current atmospheric pressure P. _Env ;

[0018] S203: Calculate when the pressure on the anode side reaches the target replacement pressure P _tar Hydrogen concentration C2 on the rear anode side;

[0019] S204: Based on the hydrogen pressure P1 on the anode side and the atmospheric pressure P... _Env Given the pressure difference ΔP and the hydrogen concentration C2 on the anode side, calculate the opening time T of the hydrogen venting valve required for replacement.

[0020] In step S202, the anode-side hydrogen pressure P1 is measured by the infeed hydrogen pressure sensor, and the atmospheric pressure P... _Env Measured using an environmental pressure sensor.

[0021] Furthermore, step S5, air intake, also includes: opening the air intake valve and closing the air bypass valve after the water pump has started successfully; if the water pump fails to start, continue to wait for it to start.

[0022] This invention also provides a fuel cell start-up system, which includes: a fuel cell stack, an ambient pressure sensor, a cooling system, an air system, and a hydrogen system. The cooling system, air system, and hydrogen system are respectively connected to and exit the fuel cell stack through three pipelines, and the specific pipeline design is as follows:

[0023] The cooling system has a series of pipes connected to a radiator, a thermostat, a fuel cell stack, and a water pump. The outlet of the water pump is connected to the inlet of the radiator and the inlet of the thermostat, forming a circulation pipeline to reduce the temperature of the fuel cell stack.

[0024] The air system is connected in sequence to: an air filter, an air compressor, an intercooler, an intake valve, an electric stack, an exhaust valve, and a mixing point. A bypass pipeline is provided between the intercooler and the mixing point, and a bypass valve is provided on the bypass pipeline.

[0025] The hydrogen system pipeline is connected in sequence to: hydrogen inlet, hydrogen injector, hydrogen pressure sensor, fuel cell stack, hydrogen discharge valve, and mixing point. A hydrogen circulation device is provided between the hydrogen discharge valve and the hydrogen injector.

[0026] The starting system of the fuel cell, consisting of the aforementioned stack, cooling system, air system, and hydrogen system, is used to execute the specific steps of the aforementioned fuel cell starting method.

[0027] The present invention has at least the following beneficial effects:

[0028] 1. This invention avoids the traditional single replacement strategy by calculating the replacement time in real time. When the parking time is short, the corresponding replacement time is shortened, thus avoiding the waste of hydrogen.

[0029] 2. The fuel cell start-up method provided by the present invention can effectively improve the hydrogen replacement speed, reduce the hydrogen replacement time, and thus shorten the start-up time; Attached Figure Description

[0030] Figure 1 A flowchart of the fuel cell start-up method provided by the present invention;

[0031] Figure 2 The diagram below shows the composition of the fuel cell start-up system provided by this invention.

[0032] Labeling Explanation: 1. Radiator; 2. Thermostat; 3. Fuel Cell Stack; 4. Water Pump; 5. Hydrogen Inlet; 6. Hydrogen Injector; 7. Hydrogen Pressure Sensor; 8. Hydrogen Discharge Valve; 9. Hydrogen Recirculation Device; 10. Mixing Point; 11. Air Filter; 12. Air Compressor; 13. Intercooler; 14. Inlet Valve; 15. Outlet Valve; 16. Bypass Valve. Detailed Implementation

[0033] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1

[0035] like Figure 1 As shown, the present invention provides a fuel cell start-up method, which is performed according to the following steps:

[0036] S1: In standby mode, the driver issues a start command, all components are powered on, the bypass valve is set to the fully open state, and the air compressor, water pump and hydrogen circulation device are started.

[0037] S2: Calculate the downtime Δt of the fuel cell system;

[0038] S3: Estimate the hydrogen concentration C1 on the anode side of the fuel cell stack based on the downtime Δt, and obtain the hydrogen pressure P1 on the anode side and the current atmospheric pressure P. _Env P1 is measured by the infeed hydrogen pressure sensor. _Env Measured by the environmental pressure sensor integrated into the fuel cell;

[0039] S4: Calculate when the pressure on the anode side reaches the target displacement pressure P _tar Hydrogen concentration C2 on the rear anode side;

[0040] S5: Based on the hydrogen pressure P1 on the anode side and the atmospheric pressure P... _Env Given the pressure difference ΔP and the hydrogen concentration C2 on the anode side, calculate the opening time T of the hydrogen venting valve required for replacement.

[0041] S6: Turn on the hydrogen supply device to introduce hydrogen into the fuel cell stack until the pressure reaches P. _tar And maintain this pressure; proceed to the next step if the air compressor and hydrogen circulation unit start successfully, otherwise continue to wait for them to start successfully;

[0042] S7: Start the hydrogen venting valve and close it when the opening time of the hydrogen venting valve reaches T.

[0043] S8: After the water pump starts successfully, open the air intake valve and close the air bypass valve; if the water pump fails to start, continue to wait for it to start, and then complete the air intake and the engine will enter the running state.

[0044] When the above method is executed, the vehicle controller performs relevant calculations, specifically as follows:

[0045] In step S2: the downtime Δt is calculated based on the current shutdown time t1 and the current startup time t2, Δt = t2 - t1;

[0046] In step S3: The hydrogen concentration C1 on the anode side of the fuel cell stack is obtained through calibration. The calibration method is as follows: after the fuel cell is shut down, the hydrogen concentration on the anode side at different times is collected by a hydrogen concentration sensor to obtain the hydrogen concentration C1 on the anode side of the fuel cell stack corresponding to the shutdown time.

[0047] In step S4: the hydrogen concentration C2 on the anode side is determined based on the hydrogen concentration C1, the hydrogen pressure P1 on the anode side, and the target replacement pressure P. _tar ,calculate, C2 ranges from 0 to 1, where 1 represents 100%.

[0048] In step S5: the required opening time T of the hydrogen discharge valve is calculated according to the following formula:

[0049]

[0050] Among them, C _tar The target concentration value is V, the total volume of the engine anode is V, and Q is the average flow rate of the replacement process: Q = K·(C _tar -C2)·ΔP, where ΔP is the hydrogen pressure P1 and atmospheric pressure P on the anode side. _Env The pressure difference, K is the proportionality coefficient, which can be obtained through calibration.

[0051] Example 2

[0052] This invention also provides a fuel cell system for completing the fuel cell start-up method of Embodiment 1. The system includes: a fuel cell stack 3, an ambient pressure sensor, a cooling system, an air system, and a hydrogen system. The cooling system, air system, and hydrogen system are respectively connected to and exit the fuel cell stack through three pipelines, and the specific pipeline design is as follows:

[0053] The cooling system has the following components connected in sequence: radiator 1, thermostat 2, fuel cell stack 3, and water pump 4. The outlet of water pump 4 is connected to the inlet of radiator 1 and the inlet of thermostat 2, forming a circulation pipeline to reduce the temperature of the fuel cell stack.

[0054] The air system is connected in sequence to: air filter 11, air compressor 12, intercooler 13, intake valve 14, fuel cell stack 3, exhaust valve 15, and mixing point 10. A bypass pipeline is provided between the intercooler 13 and the mixing point 10, and a bypass valve 16 is provided on the bypass pipeline.

[0055] The hydrogen system pipeline is connected in sequence to: hydrogen inlet 5, hydrogen injector 6, hydrogen pressure sensor 7, fuel cell stack 3, hydrogen discharge valve 8, and mixing point 10. A hydrogen circulation device 9 is installed between the hydrogen discharge valve 8 and the hydrogen injector 6.

[0056] The pipelines of the aforementioned cooling system, air system, and hydrogen system converge through the fuel cell stack, with the outlets of the air system and hydrogen system pipelines both designated as mixing points.

[0057] In actual operation, according to the fuel cell startup method of Example 1, during startup, the bypass valve on the bypass pipeline of the air system is first opened, and the air compressor, water pump, and hydrogen circulation device are started; the controller receives the anode side pressure value P1 and atmospheric pressure value P measured by the infeed hydrogen pressure sensor and the ambient pressure sensor. _Env The opening time T of the hydrogen discharge valve is calculated based on the downtime Δt of the fuel cell system, as described in Example 1. The hydrogen supply equipment is turned on, and hydrogen is introduced into the stack from the hydrogen inlet until the pressure reaches P. _tar And maintain this pressure; then when the air compressor and hydrogen circulation device start successfully, open the hydrogen discharge valve until the cumulative opening time of the hydrogen discharge valve reaches T, and then close the hydrogen discharge valve; when the water pump starts successfully, open the intake valve and close the bypass valve at the same time, so that air enters the stack from the air system pipeline, and the engine completes the start-up.

[0058] As can be seen from Example 1 and Real-time Example 2, the fuel cell startup method and system provided by the present invention can automatically calculate the hydrogen exhaust valve opening time required for each startup, and complete the startup of the corresponding fuel cell according to different shutdown times, avoiding the waste of hydrogen and shortening the startup time.

[0059] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for starting a fuel cell, characterized in that, Includes the following steps: S1: In standby mode, the driver issues a start command, and all components are powered on; S2: The controller calculates the required opening time T of the hydrogen discharge valve; S201: Calculate the downtime Δt of the fuel cell system; S202: Estimate the hydrogen concentration C1 on the anode side of the fuel cell stack based on the downtime Δt, and obtain the hydrogen pressure P1 on the anode side and the current atmospheric pressure P. _Env ; S203: Calculate when the pressure on the anode side reaches the target replacement pressure P _tar Hydrogen concentration C2 on the rear anode side; S204: Based on the hydrogen pressure P1 on the anode side and the atmospheric pressure P... _Env Given the pressure difference ΔP and the hydrogen concentration C2 on the anode side, calculate the opening time T of the hydrogen venting valve required for replacement. S3: Turn on the hydrogen supply equipment to introduce hydrogen into the fuel cell stack until the pressure reaches the target replacement pressure P. _tar And maintain that pressure; If the air compressor and hydrogen circulation unit start successfully, proceed to the next step; otherwise, continue waiting for them to start successfully. S4: Start the hydrogen venting valve and close it when the opening time of the hydrogen venting valve reaches T. S5: Air intake is complete, and the engine enters operating mode; Step S1 further includes: Set the bypass valve to the fully open position and start the air compressor, water pump and hydrogen circulation device; In step S202, the anode-side hydrogen pressure P1 is measured by the infeed hydrogen pressure sensor, and the atmospheric pressure P... _Env Measured using an environmental pressure sensor.

2. The method for starting a fuel cell according to claim 1, characterized in that, The step S5 air injection into the reactor also includes: After the water pump starts successfully, open the air intake valve and close the air bypass valve.

3. A fuel cell starting system for performing the fuel cell starting method according to any one of claims 1-2, characterized in that, At least including: Fuel cell stack, ambient pressure sensor, cooling system, air system, and hydrogen system; The cooling system, air system, and hydrogen system enter and exit the fuel cell stack through three pipelines.

4. The fuel cell start-up system according to claim 3, characterized in that, The cooling system is connected in sequence to the following pipes: The system includes a radiator, a thermostat, an electric stack, and a water pump, with the outlet of the water pump connected to the inlet of the radiator and the inlet of the thermostat, respectively.

5. The fuel cell starting system according to claim 4, characterized in that, The air system is connected in sequence to the following pipes: Air filter, air compressor, intercooler, intake valve, fuel cell stack, exhaust valve, and mixing point.

6. The fuel cell starting system according to claim 5, characterized in that, The hydrogen system is connected in sequence to the following pipelines: The system includes a hydrogen inlet, a hydrogen injector, a hydrogen pressure sensor for the fuel cell stack, a hydrogen discharge valve, and a mixing point. A hydrogen circulation device is provided between the hydrogen discharge valve and the hydrogen injector.

7. The fuel cell starting system according to claim 6, characterized in that, A bypass pipeline is provided between the intercooler and the mixing point, and a bypass valve is provided on the bypass pipeline.

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