A control method for a fuel cell hydrogen supply and hydrogen recovery device

Abstract

The application discloses a control method for a hydrogen supply and return device of a fuel cell, wherein the hydrogen supply and return device comprises an ejector and proportional valves, three independent jet channels are arranged at a jet inlet of the ejector, the three jet channels are an idling jet channel, a first jet channel and a second jet channel, an outlet diameter D1 of the idling jet channel is smaller than an outlet diameter D2 of the first jet channel, and the outlet diameter D2 of the first jet channel is smaller than an outlet diameter D3 of the second jet channel, three proportional valves are arranged, and the three proportional valves are an idling proportional valve, a first proportional valve and a second proportional valve, respectively, the idling proportional valve, the first proportional valve and the second proportional valve control the idling jet channel, the first jet channel and the second jet channel, respectively, a fuel cell system controller controls the idling proportional valve, the first proportional valve and the second proportional valve to select the idling jet channel, the first jet channel and / or the second jet channel to supply hydrogen, and controls a hydrogen supply amount into a stack module to adapt to a working condition of the fuel cell.

Description

Technical field:

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a control method for a hydrogen supply and hydrogen recovery device of a fuel cell. Background technology:

[0002] A fuel cell is a power generation device that directly converts the chemical energy of fuel into electrical energy. Fuel cells have high energy conversion efficiency and are an ideal way to utilize energy.

[0003] During application, in order for the fuel cell to provide sufficient hydrogen concentration and discharge the mixed gas such as liquid water, nitrogen and a small amount of hydrogen generated after the reaction of the stack module, the supply of hydrogen and oxygen in the fuel cell must be higher than the amount consumed by the electrochemical reaction. In order to improve the utilization rate of hydrogen, hydrogen circulation is the main technical means. At present, hydrogen circulation is generally achieved through a circulation pump or an ejector. The circulation pump has mechanical moving parts, but when it is in a high temperature and high humidity working environment, its reliability is difficult to guarantee and the cost is relatively high. In addition, the circulation pump also needs to consume the additional electricity generated by the fuel cell when working, which will reduce the efficiency of the entire system. The ejector is a device that uses the pressure potential energy of the new hydrogen to convert it into a high-speed flow to eject another low-speed and low-energy flow. It has the advantages of low processing difficulty and low energy consumption. Therefore, the current hydrogen circulation is mainly achieved through the ejector.

[0004] Under the working conditions of high power and high flow of fuel cells, only a single ejector structure is needed, and its ejection effect is good. However, under the working conditions of low power and low flow of fuel cells, the ejection effect of the single ejector structure is poor, and even no ejection can be performed under low power, and there is no circulation. In order to solve the problem that the single ejector structure is not suitable for the working conditions of low power and low flow, some people have invented a solution of using multiple ejector structures; such as the publication number: CN109980249A, the invention name: Invention patent of ejector unit and fuel cell hydrogen circulation system with ejector unit. The two ejectors of this solution are arranged in series to form a multi-ejector mechanism, but the processing feasibility of this structure is poor, and the diameter of the mixing tube of the first ejector is limited to the best ejection. The injection area ratio determines that if the aperture is too small, a large pressure loss will be generated when the second ejector is working. In order to solve the shortcomings of multiple ejectors arranged in series, a structure with two ejectors arranged in parallel has been invented. For details, please refer to the announcement number: CN112072145B, and the invention name is: Invention patent for hydrogen pressure reduction control system, method, equipment, battery system and design method. Two ejectors are directly connected in parallel. This scheme has a simple structure and high feasibility. However, the two ejectors of this scheme share a proportional control valve on the hydrogen return circuit to realize the working state switching of the two ejectors. When switching, it is easy to cause pressure fluctuations, making the pressure difference control invalid, which may cause alarm shutdown at the least and damage the fuel cell stack at the worst.

[0005] In summary, the existing solution of using multiple ejectors is not perfect. In order to solve the shortcomings of using multiple ejectors, someone proposed a different solution. For details, please refer to the announcement number: CN111490268B, the invention name is: Invention patent of fuel cell system and control method of fuel cell system. This solution uses two ejectors to share a mixing chamber, so that the two sets of ejectors do not need to switch valves when working, which can avoid pressure fluctuations and cause pressure difference control failure. It has a simple structure and high feasibility. However, this solution is suitable for low-power and medium-high-power operating conditions of fuel cells, and is not suitable for idling conditions of fuel cells. Since the hydrogen demand of fuel cells is the smallest in idling conditions, if conventional low-power nozzles are used to supply new hydrogen, its kinetic energy is very weak and cannot meet the high ejection ratio requirements, resulting in a small amount of hydrogen ejection circulation, resulting in the risk of flooding of the fuel cell stack module when the fuel cell is idling, which is easy to damage the stack module. Summary of the invention:

[0006] The purpose of the present invention is to provide a control method for a fuel cell hydrogen supply and hydrogen recovery device, which can solve the technical problem that the solutions in the prior art of multiple ejectors and two ejectors sharing a mixing chamber are not suitable for the idling condition of the fuel cell. The new hydrogen is supplied by a conventional low-power nozzle, and its kinetic energy is very weak, which cannot meet the high ejection ratio requirement, resulting in a small ejection circulation volume of hydrogen, resulting in the risk of flooding of the fuel cell stack module when the fuel cell is in the idling condition, and the stack module is easily damaged.

[0007] The purpose of the present invention is achieved through the following technical solutions.

[0008] The purpose of the present invention is to provide a control method for a fuel cell hydrogen supply and hydrogen recovery device, the hydrogen supply and hydrogen recovery device includes an ejector, a proportional valve, a discharge valve, a stack module and a fuel cell system controller, high-pressure hydrogen enters the hydrogen inlet of the stack module through the proportional valve and the ejector, the hydrogen outlet of the stack module is connected to the ejector port, the proportional valve, the discharge valve and the stack module are controlled by the fuel cell system controller; the ejector is provided with a suction chamber, a mixing chamber and a diffusion chamber connected to each other, the ejector is provided with an injection inlet, an injection outlet and an ejection port, the injection inlet and the ejection port are connected to the suction chamber, and the injection outlet is connected to the diffusion chamber; the ejector The injection inlet of the device is provided with three independent jet channels that share a mixing chamber. The three jet channels are an idle jet channel, a first jet channel, and a second jet channel. The outlet diameter of the idle jet channel is D1, the outlet diameter of the first jet channel is D2, and the outlet diameter of the second jet channel is D3, where D1<D2<D3. Three proportional valves are provided, namely an idle proportional valve, a first proportional valve, and a second proportional valve. The fuel cell system controller independently controls the idle proportional valve, the first proportional valve, and the second proportional valve to control the operation of the idle jet channel, the first jet channel, and the second jet channel respectively.

[0009] The control method comprises the following steps:

[0010] Step 1: The fuel cell system controller obtains an instruction of the required power P to be output from the outside world, and compares the required power P with the set power;

[0011] Step 2: The fuel cell system controller controls the idle proportional valve, the first proportional valve and the second proportional valve based on the comparison results, thereby selecting the idle jet channel and / or the first jet channel and / or the second jet channel to supply hydrogen, and controls the amount of hydrogen supplied to the stack module to adapt to the working conditions of the fuel cell.

[0012] Preferably, there are three working conditions of the fuel cell, namely, idle condition, low power condition, or medium-high power condition; the set power includes idle power P0 and low power P1, P0<P1; when P=P0, the fuel cell system controller enters P0 control mode, that is, idle condition control mode, the fuel cell system controller controls the idle proportional valve to open to the maximum opening, closes the second jet channel, provides the highest pressure hydrogen flow for the idle jet channel, makes the hydrogen in the idle jet channel ejected to the mixing chamber at the highest speed, generates a large negative pressure in the suction chamber, obtains a high ejection ratio, and the fuel cell system controller controls the first proportional valve to synchronously open the first jet channel in a pulsed manner to cooperate with the work of the discharge valve, so that the fuel cell is in idle condition; when P0<P≤P1, the fuel cell system controller The controller selects P1 control mode, i.e., low-power operating condition control mode, and the fuel cell system controller controls the idle proportional valve and the second proportional valve respectively to close the idle jet channel and the second jet channel, and the fuel cell system controller controls the first proportional valve to open the first jet channel, and the opening of the first proportional valve increases with the increase of P, thereby making the fuel cell in a low-power operating condition; when P>P1, the fuel cell system controller selects P2 control mode, i.e., medium- and high-power operating condition control mode, and the fuel cell system controller controls the idle proportional valve and the first proportional valve to close the idle jet channel and the first jet channel, and the fuel cell system controller controls the second proportional valve to open the second jet channel, and the opening of the second proportional valve increases with the increase of P, thereby making the fuel cell in a medium- and high-power operating condition.

[0013] Preferably, when switching the control mode, within a set time T, the corresponding proportional valve working in the previous control mode is gradually closed, and the corresponding proportional valve working in the current control mode is gradually opened to achieve flexible switching.

[0014] Preferably, the front end of the proportional valve is connected to an isolation valve, a pressure sensor PT1, a filter, and a high-pressure hydrogen source; the outside of the diffusion chamber is the outlet of the ejector device, which is connected to a safety valve and a pressure sensor PT2. The hydrogen outlet of the stack module is installed with a pressure sensor PT3 and a water vapor separator. The pressure sensors PT1, PT2, and PT3 detect the air pressure signals at each position and send them to the fuel cell system controller. The stack module is also connected to the air supply system. The pressure sensor PT4 is installed at the air inlet of the stack module. The pressure sensor PT4 detects the air path pressure signal and transmits it to the fuel cell system controller. The hydrogen outlet of the stack module is connected to the ejector port of the ejector through the water vapor separator. The water vapor separated by the water vapor separator is discharged through the exhaust valve.

[0015] Preferably, when the fuel cell is in the idle condition, in order to ensure that the pressure value FPT2 detected by the pressure sensor PT2 in the hydrogen path is greater than the pressure value FPT4 detected by the pressure sensor PT4 in the air path, the fuel cell system controller controls the idle proportional valve to open to the maximum opening to provide the highest pressure hydrogen flow to the idle jet channel, and simultaneously pulses the first jet channel to supplement the hydrogen consumed by the discharge valve; in the low power condition control mode, the first proportional valve will gradually increase its opening to provide sufficient high-pressure hydrogen flow to the first jet channel to supplement the hydrogen consumed by the discharge valve opening. Since the first proportional valve is not fully opened and has sufficient flow margin, the opening of the first proportional valve is The pressure signal detected by the pressure sensor PT2 forms a closed-loop PID control strategy that is executed in the fuel cell system controller, so that the pressure value detected by the pressure sensor PT2 is maintained within the target control range; in the medium and high power operating control mode, the second proportional valve will gradually increase its opening to provide sufficient high-pressure hydrogen flow to the second injection channel to replenish the hydrogen consumed by the opening of the discharge valve. Because the second proportional valve is not fully opened and has sufficient flow margin, the opening of the second proportional valve and the pressure signal detected by the pressure sensor PT2 form a closed-loop PID control strategy that is executed in the fuel cell system controller, so that the pressure value detected by the pressure sensor PT2 is maintained within the target control range.

[0016] Preferably, when P>P1 and P>P2, P2 is the upper limit setting power P2, the fuel cell system controller controls the idle proportional valve, the first proportional valve and the second proportional valve to open at the same time, and selects the idle jet channel, the first jet channel and the second jet channel to supply hydrogen at the same time to increase the output power of the fuel cell module.

[0017] Preferably, the idle jet channel includes an inlet section flow channel, a pressurizing section flow channel and an outlet section flow channel. The inlet section flow channel and the outlet section flow channel are straight-through flow channels. The aperture of the pressurizing section flow channel gradually decreases from the inlet section flow channel to the outlet section flow channel. Hydrogen enters from the inlet section flow channel, is pressurized through the pressurizing section flow channel, and is output from the outlet section flow channel.

[0018] Preferably, the first jet channel and the second jet channel are both straight-through flow channels, the inlet diameter of the inlet section flow channel is D4, the inlet diameter of the first jet channel is D5, and the inlet diameter of the second jet channel is D6, D4>D6>D5.

[0019] Preferably, the nozzle includes a cylindrical portion, an injection portion connected to one end of the cylindrical portion, and a clamping plate connected to the other end of the cylindrical portion. A slot cooperating with the clamping plate is provided at the hydrogen inlet end of the ejector body, the clamping plate is embedded in the slot, and the cylindrical portion and the injection portion extend into the suction chamber.

[0020] Preferably, the idle jet channel is located at the center of the nozzle, and the first jet channel and the second jet channel are distributed beside the idle jet channel.

[0021] Compared with the prior art, the present invention has the following effects:

[0022] 1) The control method for the fuel cell hydrogen supply and hydrogen recovery device provided by the present invention is provided with an idle jet channel, a first jet channel and a second jet channel at the injection inlet of the ejector of the hydrogen supply and hydrogen recovery device, and the outlet diameter D1 of the idle jet channel is smaller than the outlet diameter D2 of the first jet channel and smaller than the outlet diameter D3 of the second jet channel. The fuel cell system controller controls the idle proportional valve, the first proportional valve and the second proportional valve to select the idle jet channel and / or the first jet channel and / or the second jet channel to supply hydrogen, and controls the hydrogen supply amount entering the stack module to adapt to the working condition of the fuel cell. When the fuel cell is in the idle working condition, the idle jet channel is selected to transport hydrogen. When the fuel cell is in the low power working condition, the first jet channel is selected to transport hydrogen. To deliver hydrogen, when the fuel cell is in medium and high power working conditions, the second jet channel is selected to deliver hydrogen. Under the same flow demand, the smaller the outlet diameter of the jet channel, the greater the kinetic energy obtained when the working fluid is ejected, and the outlet diameter D1 of the idle jet channel is designed to be the smallest. When the same flow of hydrogen passes through the idle jet channel, the first jet channel and the second jet channel, the idle jet channel generates the highest injection ratio. By designing an additional jet channel specifically to cope with the idle working conditions of the fuel cell, it can be ensured that the ejector can still generate a sufficient injection ratio when the fuel cell is idling, ensuring a sufficiently high hydrogen injection circulation volume, thereby ensuring that the fuel cell stack module can work normally, avoiding the stack module from being flooded, and thus better protecting the stack module.

[0023] 2) Other advantages of the present invention are described in detail in the embodiment section. Description of the drawings:

[0024] Figure 1It is a schematic diagram of the block structure of the hydrogen supply and hydrogen recovery device for a fuel cell provided by the present invention.

[0025] Figure 2 It is a schematic diagram of the three-dimensional structure of the ejector provided by the present invention.

[0026] Figure 3 It is a schematic diagram of the exploded structure of the ejector provided by the present invention.

[0027] Figure 4 It is a schematic diagram of the main structure of the ejector provided by the present invention.

[0028] Figure 5 It is for Figure 3 Schematic diagram of the cross-sectional structure of AA provided.

[0029] Figure 6 It is a schematic diagram of the internal structure of the nozzle provided by the present invention.

[0030] Figure 7 It is a flow chart diagram of the control method provided by the present invention.

[0031] Figure 8 It is a schematic diagram of the control principle of the control method provided by the present invention.

[0032] Figure 9 It is for Figure 8 An enlarged schematic diagram of the local structure of part B is provided. Specific implementation method:

[0033] The present invention will be further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0034] Example 1: Figure 1 As shown, this embodiment provides a fuel cell hydrogen supply and hydrogen recovery device, which includes an ejector 3, a water vapor separator 4, a proportional valve, an exhaust valve 9, a fuel cell module 6 and a fuel cell system controller 20. High-pressure hydrogen enters the hydrogen inlet of the fuel cell module 6 through the proportional valve and the ejector 3, and the hydrogen outlet of the fuel cell module 6 is connected to the ejection port 16 of the ejector 3 through the water vapor separator 4. The water vapor separated by the water vapor separator 4 is discharged through the exhaust valve 9. The proportional valve, the exhaust valve 9 and the fuel cell module 6 are controlled by the fuel cell system controller 20.

[0035] like Figures 1 to 6As shown, the ejector 3 includes an ejector body 1 and a nozzle 2. The ejector body 1 is provided with a suction chamber 11, a mixing chamber 12 and a diffusion chamber 13 connected thereto. The ejector body 1 is provided with an injection inlet 14, an injection outlet 15 and an ejection port 16. The injection inlet 14 and the ejection port 16 are connected to the suction chamber 11, and the injection outlet 15 is connected to the diffusion chamber 13. Hydrogen flows into the suction chamber 11 through the hydrogen inlet 14, and the reflux hydrogen flows into the suction chamber 11 through the ejection port 16. The nozzle 2 is installed The ejector body 1 has an ejection inlet 14 at its end and is placed in the suction chamber 11. Three independent jet channels are provided inside the nozzle 2. The three independent jet channels share a mixing chamber 12. High-pressure hydrogen is ejected into the suction chamber 11 from at least one jet channel, and then mixed with the reflux hydrogen injected through the ejection port 16 in the mixing chamber 12 and enters the diffusion chamber 13, and finally outputs from the ejection outlet 15. The three jet channels are the idle jet channel 21, the first jet channel 22 and the second jet channel 2 3. The outlet diameter of the idle jet channel 21 is D1, the outlet diameter of the first jet channel 22 is D2, and the outlet diameter of the second jet channel 23 is D3, where D1<D2<D3. Three proportional valves are provided, namely the idle proportional valve 5A, the first proportional valve 5B, and the second proportional valve 5C. The idle proportional valve 5A, the first proportional valve 5B, and the second proportional valve 5C are used to control the idle jet channel 21, the first jet channel 22, and the second jet channel 23, respectively. The idle proportional valve 5A, the first proportional valve 5B, and the second proportional valve 5C are all controlled by the fuel cell system controller 20. The fuel cell system controller 20 controls the idle proportional valve 5A, the first proportional valve 5B, and the second proportional valve 5C to select the idle jet channel 21 and / or the first jet channel 22 and / or the second jet channel 23 to supply hydrogen, thereby controlling the amount of hydrogen supplied to the fuel cell stack module 6 to adapt to the operating conditions of the fuel cell, so that the fuel cell has three operating conditions: idle, low power, and medium-high power.

[0036] The ejector provided by this solution is provided with an independent idle jet channel 21, a first jet channel 22 and a second jet channel 23 inside the nozzle 2, and the outlet diameter D1 of the idle jet channel 21 is smaller than the outlet diameter D2 of the first jet channel 22 and smaller than the outlet diameter D3 of the second jet channel 23. By selecting different jet channels, the amount of hydrogen output by the ejector body 1 can be changed to change the working condition of the fuel cell, so that the fuel cell has three working conditions: idle, low power and medium and high power. When the fuel cell is in the idle working condition, the idle jet channel 21 is selected to transport hydrogen. When the fuel cell is in the low power working condition, the first jet channel 22 is selected to transport hydrogen. When the fuel cell is in the medium and high power working condition, the second jet channel 23 is selected to transport hydrogen. Under the same flow demand, the smaller the outlet diameter of the jet channel, the greater the amount of hydrogen obtained when the working fluid is ejected. The greater the kinetic energy, the smaller the outlet diameter D1 of the idle jet channel 21 is designed to be. When the same flow rate of hydrogen passes through the idle jet channel 21, the first jet channel 22 and the second jet channel 23, the idle jet channel 21 generates the highest injection ratio. By designing an additional jet channel specifically to cope with the idle working condition of the fuel cell, it can be ensured that when the fuel cell is idling, the ejector 3 can still generate a sufficient injection ratio, ensuring a sufficiently high hydrogen injection circulation volume, thereby ensuring that the fuel cell stack module 6 can work normally and avoiding the stack module 6 from being flooded, thereby better protecting the stack module 6, and integrating the three jet channels into one nozzle, so that the ejector has a high degree of integration; in addition, since a mixing chamber is shared, the electromagnetic switching valve does not need to switch the reflux port when different jet channels are working, which can avoid pressure fluctuations caused by switching the electromagnetic valve.

[0037] It should be noted that the injection ratio refers to the ratio of the gas flow rate sucked into the suction chamber 11 to the gas flow rate ejected from the nozzle 2. When the same flow rate of hydrogen passes through the idle jet channel 21, the first jet channel 22 and the second jet channel 23, the injection ratio generated by the idle jet channel 21 is the highest because the outlet diameter D1 of the idle jet channel 21 is the smallest. According to the kinetic energy calculation formula: E = 1 / 2mv2, it can be seen that when the mass flow rate m is constant, the kinetic energy E is proportional to the square of the flow rate v2 of the hydrogen; and m = ρvS, where ρ is the hydrogen density, v is the flow rate of hydrogen, and S is the cross-sectional area of ​​the jet channel. If m is constant and the density is the same, the smaller the cross-sectional area S of the nozzle, the greater the flow rate v, and the greater the kinetic energy obtained, thereby accelerating the hydrogen reflux speed and increasing the gas flow rate inhaled by the suction chamber 11. The gas flow rate ejected from the nozzle 2 decreases as the outlet diameter decreases, thereby obtaining a high ejection ratio. Therefore, in this scheme, the ejection ratio generated by the idle jet channel 21 is the highest, the ejection ratio generated by the first jet channel 22 is second, and the ejection ratio generated by the second jet channel 23 is the smallest.

[0038] As a preferred solution, Figure 1 As shown, the front end of the proportional valve is connected to an isolation valve, a pressure sensor PT1, a filter, and a high-pressure hydrogen source; the outside of the diffusion chamber is the outlet of the ejector device, which is connected to a safety valve and a pressure sensor PT2. The hydrogen outlet of the fuel cell module 6 is installed with a pressure sensor PT3. The pressure sensors PT1, PT2, and PT3 detect the air pressure signals at each position and send them to the fuel cell system controller 20. The fuel cell module 6 is also connected to the air supply system. A pressure sensor PT4 is installed at the air inlet of the fuel cell module 6. The pressure sensor PT4 detects the air path pressure signal and transmits it to the fuel cell system controller 20.

[0039] As a preferred solution, Figure 5 and Figure 6 As shown, the idle jet channel 21 includes an inlet section flow channel 211, a pressurizing section flow channel 212 and an outlet section flow channel 213. The inlet section flow channel 211 and the outlet section flow channel 213 are straight-through flow channels. The aperture of the pressurizing section flow channel 212 gradually decreases from the inlet section flow channel 211 to the outlet section flow channel 213. Hydrogen enters from the inlet section flow channel 211, is pressurized by the pressurizing section flow channel 212, and is output from the outlet section flow channel 213. The design of the pressurizing section flow channel 212 can enable the hydrogen to obtain greater kinetic energy when it is output, ensuring that a higher injection ratio can be obtained when using the idle jet channel 21 to transport hydrogen.

[0040] As a preferred solution, Figure 5 and Figure 6 As shown, the first jet channel 22 and the second jet channel 23 are both straight-through flow channels, which are simple to process. The inlet diameter of the inlet section flow channel 211 is D4, the inlet diameter of the first jet channel 22 is D5, and the inlet diameter of the second jet channel 23 is D6. D4>D6>D5. The inlet diameter of the idle jet channel 21 is designed to be the largest, while the outlet diameter is designed to be the smallest. This is more conducive to pressurizing the hydrogen passing through the idle jet channel 21 and then outputting it, so that the hydrogen obtains higher kinetic energy when it is ejected through the idle jet channel 21.

[0041] As a preferred solution, Figures 3 to 6 As shown, the nozzle 2 includes a cylindrical portion 24, an injection portion 25 connected to one end of the cylindrical portion 24 and a clamping plate 26 connected to the other end of the cylindrical portion 24. A clamping groove 17 cooperating with the clamping plate 26 is provided at the hydrogen inlet 14 end of the ejector body 1. The clamping plate 26 is embedded in the clamping groove 17. The cylindrical portion 24 and the injection portion 25 extend into the suction chamber 11. The structure is simple and the installation is convenient.

[0042] As a preferred solution, Figures 2 to 6 As shown, a flange 18 is also provided at the hydrogen inlet 14 end of the ejector body 1 to facilitate the installation of the ejector 3.

[0043] As a preferred solution, Figures 2 to 6 As shown, the idle jet channel 21 is located in the center of the nozzle 2, and the first jet channel 22 and the second jet channel 23 are distributed beside the idle jet channel 21, and the first jet channel 22 forms an angle with the central axis of the nozzle 2, and the second jet channel 23 forms an angle with the central axis of the nozzle 2, so that the outlets of the first jet channel 22 and the second jet channel 23 are concentrated in the center of the nozzle 2, and hydrogen is injected from the center position of the ejector body as much as possible, thereby ensuring the function of the ejector. In addition, since the structure of the idle jet channel 21 is divided into three sections, placing the idle jet channel 21 in the center of the nozzle 2 is more conducive to processing, and placing the idle jet channel 21 in the center of the nozzle 2 can also reduce the loss of hydrogen during injection, ensure the pressure of the idle jet channel 21 during injection, so that the ejector has a sufficient injection ratio when the fuel cell is in idle condition.

[0044] Embodiment 2: This embodiment provides a control method for a fuel cell hydrogen supply and hydrogen recovery device, and the control method includes the following steps.

[0045] Step 1: The fuel cell system controller 20 obtains an instruction of a required power P to be output from the outside, and compares the required power P with the set power.

[0046] Step 2: The fuel cell system controller 20 controls the idle proportional valve 5A, the first proportional valve 5B and the second proportional valve 5C according to the comparison results, thereby selecting the idle jet channel 21 and / or the first jet channel 22 and / or the second jet channel 23 to supply hydrogen, and controls the amount of hydrogen supplied to the stack module 6 to adapt to the working conditions of the fuel cell.

[0047] Specifically, there are three operating conditions for the fuel cell, namely, idle operating condition, low power operating condition, and medium-high power operating condition; the set power includes idle power P0 and low power P1, P0<P1.

[0048] like Figure 7As shown, when P=P0, the fuel cell system controller 20 enters the P0 control mode, that is, the idle condition control mode, and the fuel cell system controller 20 controls the idle proportional valve 5A to open to the maximum opening, closes the second jet channel 23, and provides the idle jet channel 21 with the highest pressure hydrogen flow, so that the hydrogen in the idle jet channel 21 is ejected to the mixing chamber 12 at the highest speed, generates a large negative pressure in the suction chamber 11, and obtains a high ejection ratio, and the fuel cell system controller 20 controls the first proportional valve 5B to synchronously open the first jet channel 22 in a pulsed manner to cooperate with the operation of the discharge valve 9, so that the fuel cell is in the idle condition; in this embodiment, the opening and closing of the first proportional valve 5B is synchronized with the opening and closing of the discharge valve 9, and the idle proportional valve 5A is continuously open under the idle condition of the fuel cell. The working mode of the discharge valve 9 is intermittent opening or pulse opening. The fuel cell system controller 20 controls the first proportional valve 5B to open in a pulsed manner to cooperate with the operation of the discharge valve 9, replenish the hydrogen consumed by the discharge valve 9, and ensure that the hydrogen path pressure value FPT2 is greater than the air path pressure value FPT4.

[0049] When the fuel cell is in the idle condition, in order to ensure that the pressure value FPT2 detected by the pressure sensor PT2 in the hydrogen path is greater than the pressure value FPT4 detected by the pressure sensor PT4 in the air path, the fuel cell system controller 20 controls the idle proportional valve 5A to open to the maximum opening to provide the highest pressure hydrogen flow for the idle jet channel 21, and simultaneously pulses the first jet channel 22 to supplement the hydrogen consumed by the discharge valve 9. In order to avoid the hydrogen consumption exceeding the hydrogen supply limit of the idle jet channel 21 during the operation of the discharge valve, the first jet channel is assisted to supplement the hydrogen fuel, so that the fuel cell can ensure that the hydrogen pressure is greater than the air pressure under the idle condition, thereby ensuring that the fuel cell can work normally.

[0050] like Figure 7 As shown, when P0<P≤P1, the fuel cell system controller 20 selects the P1 control mode, that is, the low-power operating condition control mode, and the fuel cell system controller 20 controls the idle proportional valve 5A and the second proportional valve 5C to close the idle jet channel 21 and the second jet channel 23 respectively. The fuel cell system controller 20 controls the first proportional valve 5B to open the first jet channel 22. The opening of the first proportional valve 5B increases with the increase of P, thereby putting the fuel cell in a low-power operating condition.

[0051] In the low-power operating control mode, the first proportional valve 5B will gradually increase its opening to provide sufficient high-pressure hydrogen flow to the first injection channel 22 to replenish the hydrogen consumed by the opening of the discharge valve 9. Because the first proportional valve 5B is not fully opened to have sufficient flow margin, the opening of the first proportional valve 5B and the pressure signal detected by the pressure sensor PT2 form a closed-loop PID control strategy, which is executed by the fuel cell system controller 20 to maintain the pressure value detected by the pressure sensor PT2 within the target control range.

[0052] like Figure 7 As shown, when P>P1, the fuel cell system controller 20 selects the P2 control mode, that is, the medium-high power operating condition control mode, the fuel cell system controller 20 controls the idle proportional valve 5A and the first proportional valve 5B to close the idle jet channel 21 and the first jet channel 22, and the fuel cell system controller 20 controls the second proportional valve 5C to open the second jet channel 23. The opening of the second proportional valve 5C increases with the increase of P, thereby putting the fuel cell in the medium-high power operating condition.

[0053] In the medium and high power operating control mode, the second proportional valve 5C will gradually increase its opening to provide sufficient high-pressure hydrogen flow to the second injection channel 23 to replenish the hydrogen consumed by the opening of the discharge valve 9. Because the second proportional valve 5C is not fully opened to have sufficient flow margin, the opening of the second proportional valve 5C and the pressure signal detected by the pressure sensor PT2 form a closed-loop PID control strategy, which is executed in the fuel cell system controller 20 to keep the pressure value detected by the pressure sensor PT2 within the target control range.

[0054] As a preferred solution, when P>P1 and P>P2, P2 is the upper limit setting power P2, P2>P1, the fuel cell system controller 20 controls the idle proportional valve 5A, the first proportional valve 5B and the second proportional valve 5C to open at the same time, and selects the idle jet channel 21, the first jet channel 22 and the second jet channel 23 to supply hydrogen at the same time to increase the output power of the fuel cell stack module 6. By intervening the idle jet channel 21, the first jet channel 22 and the second jet channel 23 to supply hydrogen, the working range of the ejector 3 can be expanded.

[0055] As a preferred solution, Figure 8 and Figure 9 As shown, when switching the control mode, within the set time T, the corresponding proportional valve working in the previous control mode gradually closes, and the corresponding proportional valve working in the current control mode gradually opens to achieve flexible switching, thereby avoiding the phenomenon of air pressure fluctuation caused by switching between different working conditions of the fuel cell and ensuring the smooth operation of the fuel cell.

[0056] The above embodiments are preferred implementations of the present invention, but the implementations of the present invention are not limited thereto. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention are equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A control method for a fuel cell hydrogen supply and hydrogen recovery device, the hydrogen supply and hydrogen recovery device comprising an ejector (3), a proportional valve, a discharge valve (9), a stack module (6) and a fuel cell system controller (20), wherein high-pressure hydrogen enters the hydrogen inlet of the stack module (6) through the proportional valve and the ejector (3), the hydrogen outlet of the stack module (6) is connected to the ejection port (16) of the ejector (3), and the proportional valve, the discharge valve (9) and the stack module (6) are controlled by the fuel cell system controller (20); The ejector (3) is provided with a suction chamber (11), a mixing chamber (12) and a diffusion chamber (13) which are connected to each other. The ejector (3) is provided with an injection inlet (14), an injection outlet (15) and an ejection port (16). The injection inlet (14) and the ejection port (16) are connected to the suction chamber (11), and the ejection outlet (15) is connected to the diffusion chamber (13). The invention is characterized in that: The ejector (3) is provided with three independent jet channels sharing a mixing chamber (12), the three jet channels being an idle jet channel (21), a first jet channel (22) and a second jet channel (23), the outlet diameter of the idle jet channel (21) being D1, the outlet diameter of the first jet channel (22) being D2, and the outlet diameter of the second jet channel (23) being D3, where D1<D2<D3; three proportional valves are provided, the three proportional valves being an idle proportional valve (5A), a first proportional valve (5B) and a second proportional valve (5C), and the fuel cell system controller (20) independently controls the idle proportional valve (5A), the first proportional valve (5B) and the second proportional valve (5C) to control the operation of the idle jet channel (21), the first jet channel (22) and the second jet channel (23) respectively; The control method comprises the following steps: Step 1: The fuel cell system controller (20) obtains an instruction of a required power P to be output given by the outside world, and compares the required power P with the set power; Step 2: The fuel cell system controller (20) controls the idle proportional valve (5A), the first proportional valve (5B) and the second proportional valve (5C) according to the comparison result, thereby selecting the idle jet passage (21) and / or the first jet passage (22) and / or the second jet passage (23) to supply hydrogen, and controls the amount of hydrogen supplied to the fuel cell stack module (6) to adapt to the working conditions of the fuel cell; There are three operating conditions for the fuel cell, namely, idle condition, low power condition, and medium-high power condition; the set power includes idle power P0 and low power P1, P0<P1; When P=P0, the fuel cell system controller (20) enters the P0 control mode, i.e., the idle operating condition control mode. The fuel cell system controller (20) controls the idle proportional valve (5A) to open to the maximum opening, closes the second jet channel (23), and provides the idle jet channel (21) with the highest pressure hydrogen flow, so that the hydrogen in the idle jet channel (21) is ejected toward the mixing chamber (12) at the highest speed, generates a large negative pressure in the suction chamber (11), and obtains a high ejection ratio. The fuel cell system controller (20) controls the first proportional valve (5B) to synchronously open the first jet channel (22) in a pulsed manner to cooperate with the operation of the discharge valve (9), so that the fuel cell is in the idle operating condition. When P0<P≤P1, the fuel cell system controller (20) selects the P1 control mode, i.e., the low-power operating condition control mode, and the fuel cell system controller (20) controls the idle proportional valve (5A) and the second proportional valve (5C) to close the idle jet passage (21) and the second jet passage (23), respectively. The fuel cell system controller (20) controls the first proportional valve (5B) to open the first jet passage (22), and the opening of the first proportional valve (5B) increases as P increases, thereby placing the fuel cell in a low-power operating condition. When P>P1, the fuel cell system controller (20) selects the P2 control mode, i.e., the medium-high power operating condition control mode. The fuel cell system controller (20) controls the idle proportional valve (5A) and the first proportional valve (5B) to close the idle jet passage (21) and the first jet passage (22). The fuel cell system controller (20) controls the second proportional valve (5C) to open the second jet passage (23). The opening of the second proportional valve (5C) increases as P increases, thereby placing the fuel cell in the medium-high power operating condition.

2. The control method for a fuel cell hydrogen supply and hydrogen recovery device according to claim 1, characterized in that: When switching the control mode, within the set time T, the corresponding proportional valve working in the previous control mode gradually closes, and the corresponding proportional valve working in the current control mode gradually opens to achieve flexible switching.

3. A control method for a fuel cell hydrogen supply and hydrogen recovery device according to claim 1 or 2, characterized in that: The front end of the proportional valve is connected to an isolation valve, a pressure sensor PT1, a filter and a high-pressure hydrogen source; the outside of the diffusion chamber (13) is the outlet of the ejector device connected to a safety valve and a pressure sensor PT2; the hydrogen outlet of the stack module (6) is installed with a pressure sensor PT3 and a water vapor separator (4); the pressure sensors PT1, PT2 and PT3 detect air pressure signals at various positions and send them to the fuel cell system controller (20); the stack module (6) is also connected to an air supply system; the air inlet of the stack module (6) is installed with a pressure sensor PT4; the pressure sensor PT4 detects an air path pressure signal and sends it to the fuel cell system controller (20); the hydrogen outlet of the stack module (6) is connected to the ejector port (16) of the ejector (3) through the water vapor separator (4); the water vapor separated by the water vapor separator (4) is discharged through the discharge valve (9).

4. A control method for a fuel cell hydrogen supply and hydrogen recovery device according to claim 3, characterized in that: When the fuel cell is in an idle state, in order to ensure that the pressure value FPT2 detected by the pressure sensor PT2 in the hydrogen path is greater than the pressure value FPT4 detected by the pressure sensor PT4 in the air path, the fuel cell system controller (20) controls the idle proportional valve (5A) to open to the maximum opening to provide the idle jet passage (21) with the highest pressure hydrogen flow, and simultaneously pulse-opens the first jet passage (22) to replenish the hydrogen consumed by the discharge valve (9); In the low power operating control mode, the first proportional valve (5B) will gradually increase its opening to provide sufficient high-pressure hydrogen flow to the first jet passage (22) to supplement the hydrogen consumed by the opening of the discharge valve (9). Because the first proportional valve (5B) is not fully opened and has sufficient flow margin, the opening of the first proportional valve (5B) and the pressure signal detected by the pressure sensor PT2 form a closed-loop PID control strategy that is executed in the fuel cell system controller (20) to maintain the pressure value detected by the pressure sensor PT2 within the target control range; In the medium and high power operating control mode, the second proportional valve (5C) will gradually increase its opening to provide sufficient high-pressure hydrogen flow to the second jet channel (23) to replenish the hydrogen consumed by the opening of the discharge valve (9). Because the second proportional valve (5C) is not fully opened and has sufficient flow margin, the opening of the second proportional valve (5C) and the pressure signal detected by the pressure sensor PT2 form a closed-loop PID control strategy, which is executed in the fuel cell system controller (20) to maintain the pressure value detected by the pressure sensor PT2 within the target control range.

5. The control method for a fuel cell hydrogen supply and hydrogen recovery device according to claim 3, characterized in that: When P>P1 and P>P2, P2 is the upper limit set power P2, the fuel cell system controller (20) controls the idle proportional valve (5A), the first proportional valve (5B) and the second proportional valve (5C) to open simultaneously, and selects the idle jet channel (21), the first jet channel (22) and the second jet channel (23) to supply hydrogen simultaneously, so as to increase the output power of the fuel cell stack module (6).

6. The control method for a fuel cell hydrogen supply and hydrogen recovery device according to claim 3, characterized in that: The idle jet channel (21) comprises an inlet section flow channel (211), a pressurizing section flow channel (212) and an outlet section flow channel (213). The inlet section flow channel (211) and the outlet section flow channel (213) are straight-through flow channels. The aperture of the pressurizing section flow channel (212) gradually decreases from the inlet section flow channel (211) toward the outlet section flow channel (213). Hydrogen enters from the inlet section flow channel (211), is pressurized by the pressurizing section flow channel (212), and is then output from the outlet section flow channel (213).

7. A control method for a fuel cell hydrogen supply and hydrogen recovery device according to claim 6, characterized in that: The first jet channel (22) and the second jet channel (23) are both straight-through flow channels, the inlet diameter of the inlet section flow channel (211) is D4, the inlet diameter of the first jet channel (22) is D5, and the inlet diameter of the second jet channel (23) is D6, where D4>D6>D5.

8. The control method for a fuel cell hydrogen supply and hydrogen recovery device according to claim 7, characterized in that: The idle jet passage (21) is located in the center of the nozzle (2), and the first jet passage (22) and the second jet passage (23) are distributed beside the idle jet passage (21).

9. A control method for a fuel cell hydrogen supply and hydrogen recovery device according to claim 8, characterized in that: The nozzle (2) comprises a cylindrical portion (24), an ejection portion (25) connected to one end of the cylindrical portion (24), and a clamping plate (26) connected to the other end of the cylindrical portion (24). The nozzle (2) is mounted at the ejection inlet (14) end of the ejector body (1) and is placed in the suction chamber (11). A clamping groove (17) cooperating with the clamping plate (26) is provided at the ejection inlet (14) end of the ejector body (1). The clamping plate (26) is embedded in the clamping groove (17). The cylindrical portion (24) and the ejection portion (25) extend into the suction chamber (11).

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