A fuel cell system and control method thereof

Abstract

The present invention discloses a fuel cell system and a control method thereof, comprising a fuel cell module and a fuel cell system controller, wherein a hydrogen path system comprises a stop valve, a first proportional valve, an ejector, a humidity sensor and a second proportional valve, external high-pressure hydrogen enters the hydrogen inlet of the fuel cell module through the stop valve, the first proportional valve and the ejector, the humidity sensor detects the humidity of the hydrogen entering the hydrogen inlet of the fuel cell module and sends a signal to the fuel cell system controller; the hydrogen outlet of the fuel cell module is connected to the return hydrogen ejection port of the ejector through a first branch, the first branch is equipped with a second proportional valve, the first proportional valve and the second proportional valve are controlled by the fuel cell system controller, and the fuel cell system controller controls the first proportional valve and the second proportional valve according to the signal sent by the humidity sensor, so as to achieve the goal of controlling the humidity of the hydrogen entering the hydrogen inlet of the fuel cell module with a simple structure and control, thereby improving the efficiency and reliability of the entire system, saving energy and reducing costs.

Description

Technical field:

[0001] The invention relates to a fuel cell system and a control method thereof. Background technology:

[0002] The hydrogen fuel cell system is an energy conversion device that converts the chemical energy of hydrogen and oxygen into electrical energy through the action of a catalyst and supplies it to electrical equipment. The hydrogen fuel cell system is a new energy source with high efficiency, high energy density, low noise and no pollution to the environment. It is a new energy power generation device with great development prospects.

[0003] The hydrogen circulation system is a very important subsystem in the fuel cell system. The hydrogen circulation system is responsible for returning the unreacted hydrogen and water vapor discharged from the hydrogen outlet of the fuel cell stack to the hydrogen inlet of the fuel cell stack. After being mixed with the pure hydrogen at the inlet of the fuel cell stack, the hydrogen and water vapor are sent into the fuel cell stack together to ensure the normal electrochemical reaction in the fuel cell stack. In addition, the hydrogen circulation system ensures the humidity balance in the fuel cell by recycling a large amount of hydrogen and water vapor, which correspondingly improves the utilization rate of hydrogen and the economy of the entire fuel cell system.

[0004] The humidity of the hydrogen sent to the fuel cell stack is an important technical indicator. During the operation of the fuel cell, the proton exchange membrane must maintain a certain humidity to maintain high proton conductivity and good operating characteristics. If the humidity of the hydrogen entering the fuel cell stack is too low, the membrane will be too dry, causing the proton exchange membrane to lose the ability to conduct protons. In severe cases, the membrane will be dehydrated, shrink or even ruptured; if the humidity of the hydrogen entering the fuel cell stack is too high, the water content in the membrane will be too high, causing flooding and freezing under low temperature conditions, blocking the gas flow channel, and causing a significant decrease in battery performance. Therefore, how to effectively realize hydrogen circulation and accurately adjust the humidity of the hydrogen entering the fuel cell stack is a key issue to maintain the internal stability of the fuel cell and improve the performance and life of the fuel cell.

[0005] Patent CN202010457857.1 discloses a fuel cell hydrogen circulation system and a control method thereof, which realizes the coordinated control of the hydrogen humidity at the inlet of the fuel cell stack by controlling the speed of the hydrogen circulation pump in the hydrogen circulation system. However, the hydrogen circulation pump is large in size and occupies space, and requires electric drive, which increases the extra power consumption of the fuel cell system and wastes energy; in addition, this method is not accurate enough in controlling the hydrogen humidity. When the fuel cell system is running at high power, the amount of unreacted hydrogen and water discharged from the stack module is very large. The hydrogen circulation pump must increase the speed to pump the unreacted hydrogen into the hydrogen inlet of the stack module to achieve the balance of hydrogen circulation. At this time, it is possible that too much water will be pumped into the stack module, bringing risks to the fuel cell system. Summary of the invention:

[0006] The purpose of the present invention is to provide a fuel cell system to solve the technical problem that the hydrogen circulation pump in the prior art realizes hydrogen circulation, which not only takes up space and increases additional power consumption, but also cannot effectively and accurately control the humidity of the hydrogen sent to the fuel cell stack, which may bring operating system risks to the overall system.

[0007] Another object of the present invention is to provide a control method for a fuel cell system, which solves the technical problem that the fuel cell system has insufficient precision and reliability in controlling the humidity of hydrogen.

[0008] The purpose of the present invention is achieved through the following technical solutions.

[0009] The object of the present invention is to provide a fuel cell system, including a stack module, a fuel cell system controller and a hydrogen gas path system, characterized in that: the hydrogen gas path system includes a stop valve, a first proportional valve, an ejector, a humidity sensor and a second proportional valve, wherein:

[0010] External high-pressure hydrogen enters the hydrogen inlet of the fuel cell stack module through the shut-off valve, the first proportional valve and the ejector. The humidity sensor detects the humidity of the hydrogen entering the hydrogen inlet of the fuel cell stack module and sends a signal to the fuel cell system controller. The hydrogen outlet of the fuel cell stack module is connected to the return hydrogen ejection port of the ejector through the first branch. The second proportional valve is installed in the first branch. The first proportional valve and the second proportional valve are controlled by the fuel cell system controller. The fuel cell system controller controls the first proportional valve and the second proportional valve according to the signal sent by the humidity sensor to control the humidity of the hydrogen entering the hydrogen inlet of the fuel cell stack module.

[0011] The hydrogen outlet of the above-mentioned fuel cell stack module is also connected to the return hydrogen injection port of the ejector through a second branch. A water-gas separator is installed on the second branch. The hydrogen separated by the water-gas separator is transported to the return hydrogen injection port of the ejector. The water separated by the water-gas separator is discharged through the drain valve assembly. The drain valve assembly is controlled by the fuel cell system controller.

[0012] A second pressure sensor is installed at the hydrogen outlet of the above-mentioned fuel cell stack module, and the second pressure sensor transmits the pressure signal to the fuel cell system controller for control.

[0013] A first pressure sensor is arranged between the first proportional valve and the ejector to detect the hydrogen pressure. The first pressure sensor transmits the pressure signal to the fuel cell system controller. When the pressure is too high, the fuel cell system controller controls the pressure relief valve to discharge the hydrogen.

[0014] When the stack module described above is in low-power operation, the hydrogen humidity at the hydrogen inlet of the stack module is less than the first set value H1, and the fuel cell system controller opens the second proportional valve to the maximum opening.

[0015] When the fuel cell stack module described above is in high power operation, the hydrogen humidity at the hydrogen inlet of the fuel cell stack module is greater than the second set value H2, and the fuel cell system controller closes the second proportional valve.

[0016] As described above, when the humidity of the hydrogen inlet of the stack module is greater than the first set value H1 and less than the second set value H2, the fuel cell system controller controls the opening degree of the second proportional valve in real time according to the corresponding function value between the pre-calibrated operating power of the fuel cell and the required hydrogen humidity.

[0017] The drain valve assembly described above is composed of a drain valve, a heating plate and a temperature sensor. The heating plate and the temperature sensor are respectively installed on the drain valve. The heating plate heats the drain valve. The temperature sensor detects the temperature of the drain valve in real time and transmits the detected temperature signal to the fuel cell system controller.

[0018] As described above, under low temperature conditions, the fuel cell system controller controls the start and stop of the heating plate according to the temperature feedback from the temperature sensor.

[0019] The output end of the pressure relief valve is connected to the drain port of the drain valve assembly. When the hydrogen pressure is too high, the hydrogen is directly discharged into the drain port.

[0020] A control method for a fuel cell system includes a fuel cell system, wherein the fuel cell system is the fuel cell system described above, and the control method includes the following steps:

[0021] Step 1: Start the self-test by starting the machine. The humidity sensor detects whether the humidity of the hydrogen at the hydrogen inlet of the fuel cell stack is less than the first set value H1. If yes, proceed to step 2. If not, skip step 2 and go directly to step 3.

[0022] Step 2: The fuel cell system controller opens the second proportional valve to increase the air intake of the first branch;

[0023] Step 3: The humidity sensor detects whether the humidity of the hydrogen inlet of the fuel cell module is greater than the second set value H2. If yes, proceed to step 4; if not, skip step 4 and proceed directly to step 5.

[0024] Step 4: The fuel cell system controller adjusts the second proportional valve to reduce the air intake of the first branch and increase the air intake of the second branch;

[0025] Step 5: The humidity sensor detects whether the humidity at the hydrogen inlet of the stack module is greater than the first set value H1 and less than the second set value H2. If yes, proceed to step 6; if not, return to step 3;

[0026] Step 6: The fuel cell system controller adjusts the opening of the second proportional valve in real time according to the change in power consumption of the fuel cell system to ensure that the humidity at the hydrogen inlet of the stack module is between H1 and H2, where H1<H2;

[0027] Step 7: The fuel cell system enters normal operating mode.

[0028] Compared with the prior art, the present invention has the following effects:

[0029] 1) A fuel cell system, comprising a fuel cell stack module, a fuel cell system controller and a hydrogen gas path system, characterized in that: the hydrogen gas path system comprises a shut-off valve, a first proportional valve, an ejector, a humidity sensor and a second proportional valve, wherein: external high-pressure hydrogen enters the hydrogen inlet of the fuel cell stack module through the shut-off valve, the first proportional valve and the ejector, the humidity sensor detects the humidity of the hydrogen entering the hydrogen inlet of the fuel cell stack module and sends a signal to the fuel cell system controller; the hydrogen outlet of the fuel cell stack module is connected to the return hydrogen ejection port of the ejector through a first branch, the first branch is equipped with a second proportional valve, the first proportional valve and the second proportional valve are controlled by the fuel cell system controller, the fuel cell system controller controls the first proportional valve and the second proportional valve according to the signal sent by the humidity sensor, so as to control the humidity of the hydrogen entering the hydrogen inlet of the fuel cell stack module, the structure and control are simple, the number of components is reduced, the efficiency and reliability of the entire system are improved, energy is saved, and costs are reduced.

[0030] 2) Other advantages of the present invention are described in detail in the embodiment section. Description of the drawings:

[0031] Figure 1 It is a principle diagram of the first embodiment of the present invention;

[0032] Figure 2 is another principle schematic diagram of the first embodiment of the present invention;

[0033] Figure 3 is a schematic structural diagram of Embodiment 1 of the present invention;

[0034] Figure 4 It is a schematic diagram of the structural decomposition of the first embodiment of the present invention;

[0035] Figure 5 It is a schematic diagram of the second embodiment of the present invention. Specific implementation method:

[0036] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0037] like Figures 1 to 4As shown, this embodiment provides a fuel cell system, including a fuel cell stack module 201, a fuel cell system controller 202 and a hydrogen path system 203, characterized in that: the hydrogen path system 203 includes a stop valve 1, a first proportional valve 2, an ejector 4, a humidity sensor 5 and a second proportional valve 7, wherein:

[0038] External high-pressure hydrogen enters the hydrogen inlet of the fuel cell module 201 through the shut-off valve 1, the first proportional valve 2 and the ejector 4, and the humidity sensor 5 detects the humidity of the hydrogen entering the hydrogen inlet of the fuel cell module 201 and sends a signal to the fuel cell system controller 202; the hydrogen outlet of the fuel cell module 201 is connected to the return hydrogen ejection port 41 of the ejector 4 through the first branch, and the second proportional valve 7 is installed in the first branch. The first proportional valve 2 and the second proportional valve 7 are controlled by the fuel cell system controller 202. The fuel cell system controller 202 controls the first proportional valve 2 and the second proportional valve 7 according to the signal sent by the humidity sensor 5, so as to control the humidity of the hydrogen entering the hydrogen inlet of the fuel cell module 201. The structure and control are simple, the number of components is reduced, the efficiency and reliability of the entire system are improved, energy is saved, and costs are reduced.

[0039] The hydrogen outlet of the fuel cell stack module 201 is also connected to the hydrogen return injection port 41 of the injector 4 through a second branch. A water-gas separator 9 is installed on the second branch. The hydrogen separated by the water-gas separator 9 is transported to the hydrogen return injection port 41 of the injector 4. The water separated by the water-gas separator 9 is discharged through the drain valve assembly 10. The drain valve assembly 10 is controlled by the fuel cell system controller 202, and the structural arrangement is reasonable.

[0040] A second pressure sensor 8 is installed at the hydrogen outlet of the fuel cell stack module 201. The second pressure sensor 8 transmits a pressure signal to the fuel cell system controller 202 for control, so that the fuel cell system controller 202 can make various controls.

[0041] A first pressure sensor 3 is arranged between the first proportional valve 2 and the ejector 4 to detect the hydrogen pressure. The first pressure sensor 3 transmits the pressure signal to the fuel cell system controller 202. When the pressure is too high, the fuel cell system controller 202 controls the pressure relief valve 6 to discharge the hydrogen to ensure the efficiency and reliability of the whole system.

[0042] When the stack module 201 is in low-power operation, the hydrogen humidity at the hydrogen inlet of the stack module 201 is less than the first set value H1, and the fuel cell system controller 202 opens the second proportional valve 7 to the maximum opening. The low power means that the operating power of the stack module 201 is less than 30% of the rated power, thereby ensuring the efficiency and reliability of the entire system.

[0043] When the stack module 201 is in high-power operation, the hydrogen humidity at the hydrogen inlet of the stack module 201 is greater than the second set value H2, and the fuel cell system controller 202 closes the second proportional valve 7. The high power means that the operating power of the stack module 201 is greater than 75% of the rated power, thereby ensuring the efficiency and reliability of the entire system.

[0044] When the humidity at the hydrogen inlet of the stack module 201 is greater than the first set value H1 and less than the second set value H2, the fuel cell system controller 202 controls the opening degree of the second proportional valve 7 in real time according to the corresponding function value between the pre-calibrated operating power of the fuel cell and the required hydrogen humidity to ensure the efficiency and reliability of the entire system.

[0045] The drain valve assembly 10 is composed of a drain valve 101, a heating plate 102 and a temperature sensor 103. The heating plate 102 and the temperature sensor 103 are respectively installed on the drain valve 101. The heating plate 102 heats the drain valve 101. The temperature sensor 103 detects the temperature of the drain valve 101 in real time and transmits the detected temperature signal to the fuel cell system controller 202. The structure is simple and compact.

[0046] Under low temperature conditions, the fuel cell system controller 202 controls the opening and stopping of the heating plate 102 according to the temperature feedback of the temperature sensor 103 to prevent the water from freezing in the drain valve under low temperature conditions, which would cause the water to be discharged and affect the working efficiency of the fuel cell.

[0047] The output end of the pressure relief valve 6 is connected to the drain port of the drain valve assembly 10. When the hydrogen pressure is too high, the hydrogen is directly discharged into the drain port. The structure is simple and the layout is reasonable.

[0048] The working principle of this structure used in the fuel cell system:

[0049] When the fuel cell is running, the humidity sensor 5 detects that the humidity of the hydrogen at the hydrogen inlet of the stack module 201 is less than the first set value H1, and the fuel cell system controller 202 opens the second proportional valve 7 to the maximum opening. Most of the hydrogen and water discharged from the stack module 201 pass through the first branch, and directly enter the hydrogen return injection port 41 of the ejector 4 through the second proportional valve 7, and mix with the hydrogen that enters the ejector 4 through the first proportional valve 2 and enter the stack module 201 to participate in the reaction. Because there is a certain resistance inside the water-gas separator 9, a small part of the hydrogen and water pass through the second branch and enter the water-gas separator 9 for water-gas separation. After separation, the hydrogen merges with the first branch and enters the hydrogen return injection port 41 of the ejector 4. The water separated by the water-gas separator 9 is discharged through the drain valve assembly 10.

[0050] When the humidity sensor 5 detects that the humidity of the hydrogen at the hydrogen inlet of the fuel cell stack is greater than the second set value H2, it means that there is too much water in the hydrogen return, and the fuel cell system controller 202 closes the second proportional valve 7. The hydrogen and water discharged from the fuel cell stack module 201 all enter the water-gas separator 9 through the second branch, and the hydrogen after water-gas separation directly enters the hydrogen return injection port 41 of the ejector 4, and the separated water is discharged through the drain valve assembly 10.

[0051] When the humidity sensor 5 detects that the humidity of hydrogen at the hydrogen inlet of the stack is greater than the first set value H1 and less than the second set value H2, the fuel cell system controller 202 controls the opening degree of the second proportional valve 7 in real time according to the corresponding function value between the pre-calibrated operating power of the fuel cell and the required hydrogen humidity. A part of the hydrogen and water discharged from the stack module 201 enters the first branch, passes through the second proportional valve 7, and enters the return hydrogen injection port 41 of the ejector 4. Another part of the hydrogen and water discharged from the stack module 201 enters the second branch, and the water-gas separator 9 performs water-gas separation. After separation, the hydrogen merges with the first branch and enters the return hydrogen injection port 41 of the ejector 4 together.

[0052] By precisely controlling the opening of the second proportional valve 7 in this way, the circulation of hydrogen and the humidity of hydrogen entering the fuel cell stack module 201 can be controlled, with a simple structure and low cost.

[0053] Embodiment 2:

[0054] like Figure 5 As shown, a control method of a fuel cell system includes a fuel cell system, characterized in that: the fuel cell system is the fuel cell system described in the first embodiment above, and the control method includes the following steps:

[0055] Step 1: Start the self-test by starting the machine. The humidity sensor detects whether the humidity of the hydrogen at the hydrogen inlet of the fuel cell stack is less than the first set value H1. If yes, proceed to step 2. If not, skip step 2 and go directly to step 3.

[0056] Step 2: The fuel cell system controller opens the second proportional valve to increase the air intake of the first branch;

[0057] Step 3: The humidity sensor detects whether the humidity of the hydrogen inlet of the fuel cell module is greater than the second set value H2. If yes, proceed to step 4; if not, skip step 4 and proceed directly to step 5.

[0058] Step 4: The fuel cell system controller adjusts the second proportional valve to reduce the air intake of the first branch and increase the air intake of the second branch;

[0059] Step 5: The humidity sensor detects whether the humidity at the hydrogen inlet of the stack module is greater than the first set value H1 and less than the second set value H2. If yes, proceed to step 6; if not, return to step 3;

[0060] Step 6: The fuel cell system controller adjusts the opening of the second proportional valve in real time according to the change in power consumption of the fuel cell system to ensure that the humidity at the hydrogen inlet of the stack module is between H1 and H2, where H1 < H2;

[0061] Step 7: The fuel cell system enters normal operating mode.

[0062] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited thereto. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention are equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A fuel cell system, comprising a fuel cell stack module (201), a fuel cell system controller (202) and a hydrogen gas path system (203), characterized in that: The hydrogen gas circuit system (203) comprises a stop valve (1), a first proportional valve (2), an ejector (4), a humidity sensor (5) and a second proportional valve (7), wherein: External high-pressure hydrogen enters the hydrogen inlet of the stack module (201) through the stop valve (1), the first proportional valve (2) and the ejector (4); the humidity sensor (5) detects the humidity of the hydrogen entering the hydrogen inlet of the stack module (201) and sends a signal to the fuel cell system controller (202); the hydrogen outlet of the stack module (201) is connected to the return hydrogen ejection port (41) of the ejector (4) through a first branch; the first branch is equipped with a second proportional valve (7); the first proportional valve (2) and the second proportional valve (7) are controlled by the fuel cell system controller (202); the fuel cell system controller (202) controls the first proportional valve (2) and the second proportional valve (7) according to the signal sent by the humidity sensor (5) to control the humidity of the hydrogen entering the hydrogen inlet of the stack module (201); When the fuel cell stack module (201) is in low-power operation, the hydrogen humidity at the hydrogen inlet of the fuel cell stack module (201) is less than a first set value H1, and the fuel cell system controller (202) opens the second proportional valve (7) to a maximum opening; When the stack module (201) is in high-power operation, the hydrogen humidity at the hydrogen inlet of the stack module (201) is greater than a second set value H2, and the fuel cell system controller (202) is adjusted to close the second proportional valve (7); When the humidity of the hydrogen inlet of the fuel cell module (201) is greater than the first set value H1 and less than the second set value H2, the fuel cell system controller (202) controls the opening degree of the second proportional valve (7) in real time according to the corresponding function value between the pre-calibrated operating power of the fuel cell and the required hydrogen humidity.

2. A fuel cell system according to claim 1, characterized in that: The hydrogen outlet of the fuel cell stack module (201) is also connected to the hydrogen return injection port (41) of the ejector (4) through a second branch. A water-gas separator (9) is installed on the second branch. The hydrogen separated by the water-gas separator (9) is transported to the hydrogen return injection port (41) of the ejector (4). The water separated by the water-gas separator (9) is discharged through a drain valve assembly (10). The drain valve assembly (10) is controlled by the fuel cell system controller (202).

3. A fuel cell system according to claim 2, characterized in that: A second pressure sensor (8) is installed at the hydrogen outlet of the fuel cell module (201), and the second pressure sensor (8) transmits a pressure signal to the fuel cell system controller (202) for control.

4. A fuel cell system according to claim 3, characterized in that: A first pressure sensor (3) is arranged between the first proportional valve (2) and the ejector (4) to detect the hydrogen pressure. The first pressure sensor (3) transmits a pressure signal to the fuel cell system controller (202). When the pressure is too high, the fuel cell system controller (202) controls the pressure relief valve (6) to discharge the hydrogen.

5. A fuel cell system according to claim 4, characterized in that: The drain valve assembly (10) is composed of a drain valve (101), a heating plate (102) and a temperature sensor (103). The heating plate (102) and the temperature sensor (103) are respectively installed on the drain valve (101). The heating plate (102) heats the drain valve (101). The temperature sensor (103) detects the temperature of the drain valve (101) in real time and transmits the detected temperature signal to the fuel cell system controller (202).

6. A fuel cell system according to claim 5, characterized in that: In a low temperature state, the fuel cell system controller (202) controls the start and stop of the heating plate (102) according to the temperature feedback of the temperature sensor (103).

7. A fuel cell system according to claim 4, characterized in that: The output end of the pressure relief valve (6) is connected to the drain port of the drain valve assembly (10). When the hydrogen pressure is too high, the hydrogen is directly discharged into the drain port.

8. A control method for a fuel cell system, comprising a fuel cell system, characterized in that: The fuel cell system is a fuel cell system as described in any one of claims 1 to 7, and the control method comprises the following steps: Step 1: Start the self-test by starting the machine. The humidity sensor detects whether the humidity of the hydrogen at the hydrogen inlet of the fuel cell stack is less than the first set value H1. If yes, proceed to step 2. If not, skip step 2 and go directly to step 3. Step 2: The fuel cell system controller opens the second proportional valve to increase the air intake of the first branch; Step 3: The humidity sensor detects whether the humidity of the hydrogen inlet of the fuel cell module is greater than the second set value H2. If yes, proceed to step 4; if not, skip step 4 and proceed directly to step 5. Step 4: The fuel cell system controller adjusts the second proportional valve to reduce the air intake of the first branch and increase the air intake of the second branch; Step 5: The humidity sensor detects whether the humidity at the hydrogen inlet of the stack module is greater than the first set value H1 and less than the second set value H2. If yes, proceed to step 6; if not, return to step 3; Step 6: The fuel cell system controller adjusts the opening of the second proportional valve in real time according to the change in power consumption of the fuel cell system to ensure that the humidity at the hydrogen inlet of the stack module is between H1 and H2, where H1 < H2; Step 7: The fuel cell system enters normal operating mode.

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