Adjustable ejector system for fuel cells and method for flow control thereof

Abstract

The application relates to an adjustable ejector system for a fuel cell and a flow control method thereof, the system comprising an ejector body and a control part, the ejector body comprising an ejector main body, a proportional electromagnet, a proportional pressure reducing valve, a working fluid pressure sensor and an ejecting fluid pressure sensor, and further comprising four electric signal channels; the control part comprising a high-pressure hydrogen storage bottle and a proton exchange membrane fuel cell, the output of the high-pressure hydrogen storage bottle being connected with a primary fluid inlet, the input of the proton exchange membrane fuel cell being connected with a system mixed fluid outlet, the output of the proton exchange membrane fuel cell being connected with a secondary fluid inlet and an exhaust valve respectively, and the control part further comprising a control module. Compared with the prior art, the application has the advantages of active, rapid, accurate and continuous adjustment under the variable load working condition of the fuel cell system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of pneumatic control and new energy technology, and particularly relates to an adjustable ejector system for fuel cells and a flow control method thereof. BACKGROUND

[0002] With the development of industrial technology and the increase of the number of industrial equipment such as automobiles, the increase of carbon emissions has exacerbated environmental problems such as the greenhouse effect, and clean energy utilization devices and power systems have become a research hotspot in the related field. As a new energy power device with great potential in the new century, the proton exchange membrane fuel cell (PEMFC) uses hydrogen as fuel and produces non-polluting water. In addition, it also has the advantages of high energy conversion efficiency, zero emission, low working temperature, fast start-up, and is suitable for vehicles, ships and other transportation equipment with variable load conditions. Fuel cell vehicles have become one of the alternatives to fuel vehicles.

[0003] Because the hydrogen of the stack cannot be completely reacted in a short time, the current on-board fuel cell hydrogen supply mode is mainly excess supply and recycling. The existing recycling devices include two categories: circulating pumps and ejectors. The circulating pump has high controllability and a wide working range, but it needs additional power supply, has a large volume, and is easy to produce noise. In contrast, the ejector is a passive device that relies on its internal structure to achieve fluid circulation, and does not need to consume power, has low maintenance cost, small volume and low noise. Therefore, in recent years, the ejector has become the first choice for many fuel cell system hydrogen recycling devices.

[0004] The internal structure of the traditional ejector is fixed, and its design is based on a certain rated operating point. The performance of the designed ejector is best at this operating point. However, for new energy vehicle power systems, the system operating conditions are variable during actual operation. When deviating from the above rated operating point, the ejector performance will be poor, resulting in insufficient hydrogen supply for the fuel cell.

[0005] Under the limitation of the traditional ejector, the concept of adjustable ejector appears. The adjustable ejector has certain movable components inside to adjust the structural parameters of the ejector under different operating conditions to adjust the entrainment ratio, so as to adapt to the variable load operating conditions. The existing adjustable ejector is mainly passively adjusted by flow and pressure, or manually adjusted, or step-adjusted, which is difficult to achieve active, rapid, accurate and continuous adjustment to meet the dynamic response requirements of the fuel cell system under variable load operating conditions. SUMMARY

[0006] The present application aims at providing a fuel cell adjustable ejector system and a flow control method thereof to overcome the defects of the prior art.

[0007] The present application can be realized by the following technical solutions.

[0008] The present application aims at providing a fuel cell adjustable ejector system and a flow control method thereof to overcome the defects of the prior art.

[0009] The ejector body comprises an ejector shell, one end of the ejector shell is a mixed fluid outlet, and the inside of the ejector shell is sequentially provided with a diffusion chamber, a mixing chamber, a suction chamber and a nozzle from outside to inside in sequence, one end of the diffusion chamber is a mixed fluid outlet, one side of the suction chamber is provided with an ejecting fluid inlet, and one side of the nozzle is provided with a working fluid inlet;

[0010] The proportional solenoid comprises a push rod sleeve sleeved on the push rod, one side of the push rod sleeve faces the nozzle, the other side of the push rod sleeve is provided with a limiting sheet, one end of the push rod is close to the nozzle, the other end of the push rod passes through the push rod sleeve and the limiting sheet and is connected with one end of the armature, the other end of the armature is connected with one end of the spring, the other end of the spring is connected with the inside of the end cover, the outside of the end cover is provided with a control current connector, the armature is externally provided with a bearing ring, the coil is arranged outside the bearing ring, a guide sleeve is arranged between the coil and the bearing ring, the guide sleeve is inserted with a magnetic shielding ring in the middle, and the current of the control current connector is in proportional relationship with the stroke of the armature;

[0011] The output of the proportional pressure reducing valve is connected with the working fluid inlet;

[0012] The working fluid pressure sensor is arranged at the working fluid inlet, and the ejecting fluid pressure sensor is arranged at the ejecting fluid inlet;

[0013] The ejector body further comprises three fluid channels, specifically a primary fluid inlet, a secondary fluid inlet and a mixed fluid outlet, the input of the proportional pressure reducing valve is the primary fluid inlet, the ejecting fluid inlet is the secondary fluid inlet, and the mixed fluid outlet is the system mixed fluid outlet;

[0014] The ejector body further comprises four electric signal channels, specifically a proportional pressure reducing valve control signal input channel, a proportional solenoid control signal input channel, a working fluid pressure sensor signal output channel and an ejecting fluid inlet pressure sensor signal output channel;

[0015] The control part comprises a high-pressure hydrogen storage bottle and a proton exchange membrane fuel cell, an output of the high-pressure hydrogen storage bottle is connected to the primary fluid inlet, an input of the proton exchange membrane fuel cell is connected to the system mixed fluid outlet, and an output of the proton exchange membrane fuel cell is connected to the secondary fluid inlet and the exhaust valve respectively,

[0016] The control part further comprises a control module, the control module comprises a first controller, a second controller and a working flow calculator, wherein an output channel of the first controller is connected to a proportional pressure reducing valve control signal input channel,

[0017] An input channel of the first controller, a second input channel of the second controller and a third input channel of the working flow calculator are connected to an ejector fluid inlet pressure sensor signal output channel,

[0018] A first input channel of the second controller is connected to a working fluid pressure sensor signal output channel,

[0019] An output channel of the second controller is connected to a proportional solenoid control signal input channel,

[0020] A third input channel of the second controller is connected to an output channel of the working flow calculator,

[0021] A first input channel of the working flow calculator is connected to an output end of the proton exchange membrane fuel cell, and a second input channel of the working flow calculator is connected to a given current signal module.

[0022] Further, the working flow calculator comprises a first look-up table, a second look-up table, a first PID controller and a second PID controller,

[0023] Wherein a second input channel of the working flow calculator is connected to an input end of the second look-up table,

[0024] A difference between a signal of the second input channel of the working flow calculator and a signal of a first output channel of the working flow calculator is input to the first PID controller,

[0025] A first input channel of the working flow calculator is connected to an input end of the first look-up table, and a difference between a signal output by an output end of the first look-up table and a signal of a third input channel of the working flow calculator is input to the second PID controller,

[0026] Signals output by an output end of the first PID controller, an output end of the second PID controller and the second look-up table are summed and input to an output channel of the working flow calculator.

[0027] Further, the high-pressure hydrogen storage bottle is connected to an input end of a bottle port combination valve, and an output end of the bottle port combination valve is connected to the primary fluid inlet.

[0028] Further, the proton exchange membrane fuel cell comprises a cell anode and a cell cathode.

[0029] In another aspect, the present application further provides a flow control method applied to the adjustable ejector system for fuel cell as described above, the flow control method comprises the following steps:

[0030] The input channel of the first controller receives the ejector fluid pressure signal measured by the ejector fluid pressure sensor through the signal output channel of the ejector fluid inlet pressure sensor, and feeds back the signal to the first controller, and the first controller outputs the control signal of the proportional pressure reducing valve to the input channel of the proportional pressure reducing valve through the output channel;

[0031] The first input channel of the second controller receives the working fluid pressure signal measured by the working fluid pressure sensor through the signal output channel of the working fluid pressure sensor, the second input channel receives the ejector fluid pressure signal measured by the ejector fluid pressure sensor, and the third input channel receives the given working flow signal output by the working flow calculator through the output channel of the working flow calculator. The second controller calculates the electromagnetic rod stroke required to output the given flow under the current pressure according to the signals received by the three input channels, and transmits the control current signal corresponding to the electromagnetic rod stroke to the proportional electromagnet through the output channel and the proportional electromagnet control signal input channel;

[0032] The first output channel of the working flow calculator receives the actual current signal, the second output channel receives the given current signal, and the third input channel receives the ejector fluid pressure signal measured by the ejector fluid pressure sensor. The working flow calculator calculates the given working flow signal according to the signals received by the three input channels, and sends the given working flow signal to the third input channel of the second controller.

[0033] Further, the ejector fluid pressure signal measured by the ejector fluid pressure sensor received by the third input channel is used as the fuel cell anode pressure signal, and the working flow calculator calculates the given working flow signal based on the fuel cell anode pressure signal.

[0034] Further, the expression of the electromagnetic rod stroke is:

[0035] x=f2(A P )

[0036] Wherein, x is the electromagnetic rod stroke, f2 represents the functional relationship between the rod displacement and the ejector nozzle throttle area, A P represents the ejector nozzle throttle area.

[0037] Further, the expression of the ejector nozzle throttle area is:

[0038]

[0039] wherein, p is the given hydrogen mass flow signal calculated according to the load current demand, P y represents the working fluid pressure, noz represents the function of the gas subsonic / supersonic flow state at the nozzle when the working fluid and the ejector fluid pressure ratio range is different.

[0040] Further, the function y represents the gas subsonic / supersonic flow state at the nozzle when the working fluid and the ejector fluid pressure ratio range is different. noz The expression of y is:

[0041]

[0042] wherein, p represents the working fluid pressure, H R represents the ejector fluid pressure, g C represents the gas constant of hydrogen, d T represents the temperature, and k represents the adiabatic coefficient of hydrogen.

[0043] Further, the nozzle throttle flow correction coefficient is related to the structure shape at the nozzle.

[0044] Compared with the prior art, the present application has the following beneficial effects:

[0045] (1) In the present application, the proportional pressure-reducing valve is no longer used to adjust the working fluid pressure only for the purpose of adjusting the working fluid flow as in the prior art, but is used to dynamically control the working fluid pressure when the working flow changes, so as to ensure the variation of the ejector ratio under the variable load working condition. The working fluid flow is adjusted by the controller of the proportional electromagnet, and the control method can make the working fluid flow not affected by the variation and fluctuation of the inlet pressure of the ejector.

[0046] (2) In the present application, the push rod driven by the stroke control type proportional electromagnet is used to adjust the nozzle area of the ejector, and the pressure signal measured by the pressure sensor is fed back to the controller. The controller can accurately adjust the displacement of the push rod and the nozzle area through calculation, so as to further accurately control the specified working flow output. The flow control has the advantages of dynamic, continuous, fast and accurate.

[0047] (3) In the present application, the double-PID closed-loop feedback regulation mode of the actual output current signal feedback and the fuel cell anode pressure signal feedback is adopted, so that the actual output current of the fuel cell can track the specified output current, and the anode pressure of the fuel cell stack can track the nominal pressure under the variable load working condition at a certain response speed. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1Structure diagram of the present application;

[0049] Figure 2 Structure diagram of the injector body of the present application;

[0050] Figure 3 Detailed structure diagram of the injector body and proportional electromagnet of the present application;

[0051] Figure 4 Push rod position diagram of the injector body and proportional electromagnet of the present application under low load current of fuel cell stack;

[0052] Figure 5 Push rod position diagram of the injector body and proportional electromagnet of the present application under high load current of fuel cell stack;

[0053] Figure 6 Structure diagram of the control part of the present application;

[0054] Figure 7 Structure diagram of the working flow calculator UC of the present application;

[0055] In the figure, the injector body 1, the proportional electromagnet 2, the proportional pressure reducing valve 3, the working fluid pressure sensor 4, the injector fluid pressure sensor 5, the high pressure hydrogen storage bottle 6, the bottle mouth combination valve 6a, the proton exchange membrane fuel cell 7, the cell anode 7a, the cell cathode 7a, the exhaust valve 8, the control module 9, the injector shell 101, the nozzle 102, the working fluid inlet 103, the injector fluid inlet 104, the suction chamber 105, the mixing chamber 106, the diffusion chamber 107, the mixed fluid outlet 108, the push rod sleeve 201, the coil 202, the magnetic shield ring 203, the guide sleeve 204, the end cover 205, the control current joint 206, the spring 207, the bearing ring 208, the armature 209, the limit sheet 210, the push rod 211, the primary fluid inlet F1, the secondary fluid inlet F2, the mixed fluid outlet F3, the proportional pressure reducing valve control signal input channel IN1, the proportional electromagnet control signal input channel IN2, the working fluid inlet pressure sensor signal output channel OUT1, the injector fluid inlet pressure sensor signal output channel OUT2, the input channel AI1 of the first controller UA, the output channel AO1 of the first controller UA, the first input channel BI1 of the second controller UB, the second input channel BI2 of the second controller UB, the third input channel BI3 of the second controller UB, the output channel BO1 of the second controller UB, the first input channel CI1 of the working flow calculator UC, the second input channel CI2 of the working flow calculator UC, the third input channel CI3 of the working flow calculator UC, the output channel CO1 of the working flow calculator UC. DETAILED DESCRIPTION

[0056] The application will be described in detail below with reference to the drawings and specific embodiments. The embodiments are implemented on the premise of the technical solutions of the application, and detailed implementation modes and specific operation processes are given, but the protection scope of the application is not limited to the following embodiments.

[0057] The application provides an adjustable ejector system for fuel cells, and a structural diagram of the system is shown in Figure 1 The system comprises an ejector body and a control part. A structural diagram of the ejector body is shown in Figure 2 The ejector body comprises an ejector main body 1, a proportional electromagnet 2, a proportional pressure-reducing valve 3, a working fluid pressure sensor 4, and an ejecting fluid pressure sensor 5. The ejector main body 1 realizes the basic hydrogen circulation function; the proportional electromagnet 2 and the proportional pressure-reducing valve 3 respectively adjust the nozzle area of the ejector and the working fluid pressure; and the pressure sensors 4 and 5 feed back the measured pressure signals to the control part.

[0058] A detailed structural diagram of the ejector main body 1 and the proportional electromagnet 2 is shown in Figure 3 The ejector main body comprises an ejector shell 101, a nozzle 102, a working fluid inlet 103, an ejecting fluid inlet 104, a suction chamber 105, a mixing chamber 106, a diffusion chamber 107, and a mixed fluid outlet 108. One end of the ejector shell 101 is the mixed fluid outlet 108, and the inside of the ejector shell 101 is sequentially provided with the diffusion chamber 107, the mixing chamber 106, the suction chamber 105, and the nozzle 102 in order from outside to inside, the diffusion chamber 107 has one end as the mixed fluid outlet 108, one side of the suction chamber 105 is provided with the ejecting fluid inlet 104, and one side of the nozzle 102 is provided with the working fluid inlet 103.

[0059] The proportional electromagnet 2 connected to the front end of the nozzle of the ejector main body comprises a push rod sleeve 201, a coil 202, a magnetic ring 203, a guide sleeve 204, an end cover 205, a control current connector 206, a spring 207, a bearing ring 208, an armature 209, a limiting sheet 210, and a push rod 211. The push rod sleeve 201 is sleeved outside the push rod 211, one side of the push rod sleeve 201 faces the nozzle 102, the other side of the push rod sleeve 201 is provided with the limiting sheet 210, one end of the push rod 211 is close to the nozzle 102, the other end of the push rod 211 passes through the push rod sleeve 201 and the limiting sheet 210, and is connected to one end of the armature 209, the other end of the armature 209 is connected to one end of the spring 207, the other end of the spring 207 is connected to the inner side of the end cover 205, the outer side of the end cover 205 is provided with the control current connector 206, the armature 209 is externally provided with the bearing ring 208, the bearing ring 208 is externally provided with the coil 202, the coil 202 and the bearing ring 208 are provided with the guide sleeve 204, and the guide sleeve 204 is inserted with the magnetic ring 203 in the middle.

[0060] The output of the proportional pressure reducing valve 3 is connected to the working fluid inlet 103; the working fluid pressure sensor 4 is arranged at the working fluid inlet 103, and the ejector fluid pressure sensor 5 is arranged at the ejector fluid inlet 104.

[0061] The push rod sleeve 201 of the present application plays a role of separating the proportional electromagnet 2 and the ejector hydrogen flow space, and simultaneously strengthens the rigidity when the push rod 211 moves axially. The limiting sheet 210 is arranged between the push rod sleeve 201 and the armature 209, which can prevent the armature 209 from moving to the attraction area, avoid the phenomenon that the output force of the electromagnet rises sharply and cannot work normally.

[0062] The guide sleeve 204 of the present application is arranged between the armature 209, the bearing ring 208 and the coil 202, which can protect the coil 202 from abrasion and fracture, and simultaneously form a special magnetic circuit structure, so that the output of the electromagnet is proportional to the input current. The front and rear sections of the guide sleeve 204 are made of magnetic conductive material, and a magnetic separation ring 203 made of non-magnetic conductive material is inserted between the two sections, which can change the magnetic resistance of the magnetic circuit and improve the sensitivity and response speed of the electromagnet.

[0063] Meanwhile, the system comprises three fluid channels: a primary fluid inlet F1, a secondary fluid inlet F2 and a mixed fluid outlet F3; and four electric signal channels: a proportional pressure reducing valve control signal input channel IN1, a proportional electromagnet control signal input channel IN2, a working fluid inlet pressure sensor signal output channel OUT1 and an ejector fluid inlet pressure sensor signal output channel OUT2.

[0064] The structure diagram of the control part is shown in Figure 6 The control part comprises a high-pressure hydrogen storage bottle 6 and a proton exchange membrane fuel cell 7. The output of the high-pressure hydrogen storage bottle 6 is connected to the primary fluid inlet F1, the input of the proton exchange membrane fuel cell 7 is connected to the mixed fluid outlet F3 of the system, and the output of the proton exchange membrane fuel cell 7 is connected to the secondary fluid inlet F2 and an exhaust valve 8 respectively. The high-pressure hydrogen storage bottle 6 is connected to the input end of a bottle port combination valve 6a, and the output end of the bottle port combination valve 6a is connected to the primary fluid inlet F1. The proton exchange membrane fuel cell 7 comprises a cell anode 7a and a cell cathode 7b.

[0065] The control part further comprises a control module 9, which comprises a first controller UA, a second controller UB and a working flow rate calculator UC. The output channel AO1 of the first controller UA is connected to the proportional pressure reducing valve control signal input channel IN1.

[0066] The first input channel AI1 of the first controller UA, the second input channel BI2 of the second controller UB and the third input channel CI3 of the working flow rate calculator UC are all connected to the ejector fluid inlet pressure sensor signal output channel OUT2.

[0067] The first input channel BI1 of the second controller UB is connected to the output channel OUT1 of the working fluid pressure sensor signal.

[0068] The output channel BO1 of the second controller UB is connected to the input channel IN2 of the proportional electromagnet control signal,

[0069] The third input channel BI3 of the second controller UB is connected to the output channel CO1 of the working flow rate calculator UC.

[0070] The first input channel CI1 of the working flow rate calculator UC is connected to the output end of the proton exchange membrane fuel cell 7, and the second input channel CI2 of the working flow rate calculator UC is connected to the given current signal module.

[0071] The structure diagram of the working flow rate calculator is shown in Figure 7 The working flow rate calculator UC includes a first lookup table UC1, a second lookup table UC2, a first PID controller and a second PID controller. The second input channel CI2 of the working flow rate calculator UC is connected to the input end of the second lookup table UC2, the difference between the signal of the second input channel CI2 and the signal of the first output channel CI1 is input to the first PID controller, the first input channel CI1 of the working flow rate calculator UC is connected to the input end of the first lookup table UC1, the difference between the signal output by the output end of the first lookup table UC1 and the signal of the third input channel CI3 of the working flow rate calculator UC is input to the second PID controller, the signals output by the output end of the first PID controller, the output end of the second PID controller and the output end of the second lookup table UC2 are summed and input to the output channel CO1 of the working flow rate calculator UC.

[0072] The working principle of the adjustable ejector system for fuel cells of the present application is as follows:

[0073] The hydrogen pressure stored in the high-pressure hydrogen storage bottle 6 is generally 35 MPa or 70 MPa, and the pressure is reduced to the range of the proportional pressure reducing valve inlet pressure through the pressure reducing valve of the bottle port combination valve 6a. The working fluid of the ejector is the primary flow hydrogen gas from the high-pressure hydrogen storage bottle 6, which enters the fuel cell anode 7a through the bottle port combination valve 6a, the proportional pressure reducing valve 3 and the ejector body 1. A part of the primary flow hydrogen gas participates in the electrochemical reaction, and the other part of the secondary flow hydrogen gas which is not completely reacted is transported to the ejector fluid inlet 104 through the anode gas outlet pipeline and then enters the anode again after mixing with the primary flow. Generally, the mass flow rate ratio of the secondary flow to the primary flow is taken as the ejecting coefficient or the ejecting ratio of the ejector. The exhaust valve 8 is intermittently opened for exhaust or constantly opened for leakage, which aims to exhaust the accumulated impurity gas.

[0074] For the adjustable ejector system for fuel cells described above, the flow control method includes the following steps:

[0075] The input channel AI1 of the first controller UA receives the ejector fluid pressure signal measured by the ejector fluid pressure sensor 5 through the ejector fluid inlet pressure sensor signal output channel OUT2, and feeds it back to the first controller UA, which outputs the control signal of the proportional pressure-reducing valve 3 to the proportional pressure-reducing valve control signal input channel IN1 through the output channel AO1.

[0076] The first input channel BI1 of the second controller UB receives the working fluid pressure signal measured by the working fluid pressure sensor 4 through the working fluid pressure sensor signal output channel OUT1, the second input channel BI2 receives the ejector fluid pressure signal measured by the ejector fluid pressure sensor 5, and the third input channel BI3 receives the given working flow signal output by the working flow calculator UC through the output channel CO1 of the working flow calculator UC. The second controller UB calculates the electromagnetic iron push rod stroke required for outputting the given flow at the current pressure according to the signals received by the three input channels, and transmits the control current signal corresponding to the electromagnetic iron push rod stroke to the proportional electromagnetic iron 2 through the output channel BO1 and the proportional electromagnetic iron control signal input channel IN2.

[0077] The first output channel CI1 of the working flow calculator UC receives the actual current signal, the second output channel CI2 receives the given current signal, and the third input channel CI3 receives the ejector fluid pressure signal measured by the ejector fluid pressure sensor 5. The working flow calculator UC calculates the given working flow signal according to the signals received by the three input channels, and sends the given working flow signal to the third input channel BI3 of the second controller UB.

[0078] The above three steps are performed simultaneously during the operation of the system.

[0079] During the hydrogen circulation process, the ejector body 1 and the proportional electromagnetic iron 2 are controlled by the control module 9. The control module includes the controllers UA, UB and the working flow calculator UC, and their respective I / O channels. The controller UA has the input channel AI1 and the output channel AO1. AI1 receives the ejector fluid pressure signal measured by the pressure sensor 5, and feeds it back to the controller UA. AO1 outputs the control signal of the proportional pressure-reducing valve 3 to adjust the working fluid pressure: when the load current is low, the anode pressure and the exhaust pipe pressure are low. In order to enable the ejector to smoothly inject the secondary flow gas into the suction chamber by the pressure difference, it is necessary to make the working fluid pressure low. Similarly, when the load current is high, the anode pressure and the exhaust pipe pressure are high. In order to avoid excessive ejector ratio and cause the impurity gas content of the stack to exceed the standard, it is necessary to make the working fluid pressure high.

[0080] The controller UB has input channels BI1, BI2, BI3, and an output channel BO1. BI1 receives the working fluid pressure signal measured by the pressure sensor 4, BI2 receives the ejector fluid pressure signal measured by the pressure sensor 5, and BI3 receives the given working flow rate signal output by the working flow rate calculator UC. The controller UB calculates the electromagnetic plunger stroke required to output the given flow rate at the current pressure based on the above signals, and outputs the corresponding control current signal to the proportional electromagnetic iron 2 via BO1. The calculation method of the plunger stroke is as follows:

[0081] x = f2(A P )

[0082]

[0083]

[0084] wherein x represents the displacement of the proportional electromagnetic plunger, A P represents the area of the ejector nozzle throttle, f2(A P ) represents the functional relationship between the plunger displacement and the area of the ejector nozzle throttle, which is related to the structural shape at the nozzle; p P represents the working fluid pressure, i.e., the outlet pressure of the proportional pressure-reducing valve, p H represents the ejector fluid pressure, i.e., the pressure of the fuel cell outlet pipeline, represents the given hydrogen mass flow rate signal calculated based on the load current demand, R g represents the gas constant of hydrogen; C d represents the nozzle throttle flow correction coefficient, which is related to the structural shape at the nozzle; T represents temperature; k represents the adiabatic coefficient of hydrogen, y noz is a function of the ratio of the working fluid pressure to the ejector fluid pressure, which represents the subsonic / supersonic flow state at the nozzle when the ratio range is different.

[0085] According to the above calculation method, the working fluid flow rate at the nozzle can be quickly, continuously, and accurately adjusted, and when the inlet pressure of the ejector changes under variable load conditions or fluctuates due to external factors, the desired primary flow hydrogen flow rate can still be output based on the given flow rate signal.

[0086] The given flow rate signal received by BI3 above comes from the working flow rate calculator UC. The calculator UC includes input channels CI1, CI2, CI3 and an output channel CO1. Among them, CI1 receives the actual current signal, CI2 receives the given current signal, CI3 receives the anode pressure signal of the fuel cell, and CO1 outputs the given flow rate signal.

[0087] For the calculator UC, CI2 receives the given current signal The required working fluid flow rate is calculated by calculator UC2 and used as the feedforward quantity for the given flow rate signal; CI1 receives the actual current signal I. st , give current With actual current I st error e I Feedback is sent to the PID controller, and the PID output is used as the current error compensation; simultaneously, based on the actual current signal I... st The nominal anode pressure of the fuel cell under each load current is determined using the lookup table UC1. CI3 receives the actual pressure signal p a The actual pressure p a With nominal pressure The error e between p The feedback is sent to the PID controller, and the PID output is used as the pressure error compensation value. The sum of the feedforward value, current error compensation value, and pressure error compensation value is used as the output of the calculator UC, i.e., the given working flow signal.

[0088] Under the control of the aforementioned control module, the adjustable ejector can dynamically adjust the primary hydrogen flow rate and ejection ratio in real time under system variable load conditions, thereby delivering the desired hydrogen flow rate to the fuel cell stack. At the same time, it can also adjust the hydrogen flow rate in real time based on anode pressure feedback and stack current feedback to maintain the performance of the stack.

[0089] Using the above flow control method, when the load current demand is low and the hydrogen flow demand is small, such as Figure 4 As shown, the controller inputs a higher control current to the control current connector 206. The coil 202 generates a large electromagnetic force that attracts the armature 209, causing it to overcome the tension of the spring 207 and drive the push rod 211 towards the ejector nozzle, forming a smaller nozzle area. When the load current demand is high and the hydrogen flow rate demand is large, such as... Figure 5 As shown, the controller sends a low control current signal, and the electromagnetic force generated by the coil 202 is small. At this time, the armature 209 drives the push rod 211 to move away from the ejector nozzle under the action of the spring force, forming a larger nozzle area.

[0090] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A flow control method applied to an adjustable ejector system for a fuel cell, characterized by, The ejector body comprises an ejector main body (1), a proportional electromagnet (2), a proportional pressure reducing valve (3), a working fluid pressure sensor (4) and an ejecting fluid pressure sensor (5), The ejector main body (1) comprises an ejector shell (101), one end of the ejector shell (101) is a mixed fluid outlet (108), the inside of the ejector shell (101) is sequentially provided with a diffusion chamber (107), a mixing chamber (106), a suction chamber (105) and a nozzle (102) from outside to inside, one end of the diffusion chamber (107) is the mixed fluid outlet (108), one side of the suction chamber (105) is provided with an ejecting fluid inlet (104), one side of the nozzle (102) is provided with a working fluid inlet (103); The proportional electromagnet (2) comprises a push rod sleeve (201) sleeved on a push rod (211), one side of the push rod sleeve (201) faces the nozzle (102), the other side of the push rod sleeve (201) is provided with a limiting sheet (210), one end of the push rod (211) is close to the nozzle (102), the other end of the push rod (211) passes through the push rod sleeve (201) and the limiting sheet (210) and is connected with one end of an armature (209), the other end of the armature (209) is connected with one end of a spring (207), the other end of the spring (207) is connected with the inside of an end cover (205), the outside of the end cover (205) is provided with a control current connector (206), the armature (209) is provided with a bearing ring (208) outside, the coil (202) is arranged outside the bearing ring (208), the guide sleeve (204) is arranged between the coil (202) and the bearing ring (208), the middle of the guide sleeve (204) is inserted into the magnetic isolation ring (203), the current of the control current connector (206) is in proportional relationship with the stroke of the armature (209); The output of the proportional pressure reducing valve (3) is connected with the working fluid inlet (103); The working fluid pressure sensor (4) is arranged at the working fluid inlet (103), and the ejecting fluid pressure sensor (5) is arranged at the ejecting fluid inlet (104); The ejector body further comprises three fluid channels, specifically a primary fluid inlet (F1), a secondary fluid inlet (F2) and a system mixed fluid outlet (F3), the input of the proportional pressure reducing valve (3) is the primary fluid inlet (F1), the ejecting fluid inlet (104) is the secondary fluid inlet (F2), and the mixed fluid outlet (108) is the system mixed fluid outlet (F3); The ejector body further comprises four electric signal channels, specifically a proportional pressure reducing valve control signal input channel (IN1), a proportional electromagnet control signal input channel (IN2), a working fluid pressure sensor signal output channel (OUT1) and an ejecting fluid inlet pressure sensor signal output channel (OUT2). The control part comprises a high-pressure hydrogen storage bottle (6) and a proton exchange membrane fuel cell (7), the output of the high-pressure hydrogen storage bottle (6) is connected with a primary fluid inlet (F1), the input of the proton exchange membrane fuel cell (7) is connected with a system mixed fluid outlet (F3), the output of the proton exchange membrane fuel cell (7) is connected with a secondary fluid inlet (F2) and an exhaust valve (8) respectively, The control part further comprises a control module (9), the control module (9) comprises a first controller (UA), a second controller (UB) and a working flow calculator (UC), wherein the output channel (AO1) of the first controller (UA) is connected with a proportional pressure reducing valve control signal input channel (IN1), The input channel (AI1) of the first controller (UA), the second input channel (BI2) of the second controller (UB) and the third input channel (CI3) of the working flow calculator (UC) are all connected with an ejector fluid inlet pressure sensor signal output channel (OUT2), The first input channel (BI1) of the second controller (UB) is connected with a working fluid pressure sensor signal output channel (OUT1), The output channel (BO1) of the second controller (UB) is connected with a proportional electromagnet control signal input channel (IN2), The third input channel (BI3) of the second controller (UB) is connected with the output channel (CO1) of the working flow calculator (UC), The first input channel (CI1) of the working flow calculator (UC) is connected with the output end of the proton exchange membrane fuel cell (7), and the second input channel (CI2) of the working flow calculator (UC) is connected with a given current signal module; The flow control method comprises the following steps: The input channel (AI1) of the first controller (UA) receives the ejector fluid pressure signal measured by the ejector fluid pressure sensor (5) through the ejector fluid inlet pressure sensor signal output channel (OUT2) and feeds it back to the first controller (UA), and the first controller (UA) outputs the control signal of the proportional pressure reducing valve (3) to the proportional pressure reducing valve control signal input channel (IN1) through the output channel (AO1); The first input channel (BI1) of the second controller (UB) receives the working fluid pressure signal measured by the working fluid pressure sensor (4) through the working fluid pressure sensor signal output channel (OUT1), the second input channel (BI2) receives the ejector fluid pressure signal measured by the ejector fluid pressure sensor (5), and the third input channel (BI3) receives the given working flow signal output by the working flow calculator (UC) through the output channel (CO1) of the working flow calculator (UC), and the second controller (UB) calculates the electromagnet push rod stroke required for output given flow under current pressure according to the signals received by the three input channels, and transmits the control current signal corresponding to the electromagnet push rod stroke to the proportional electromagnet (2) through the output channel (BO1) and the proportional electromagnet control signal input channel (IN2). The first input channel (CI1) of the working flow rate calculator (UC) receives an actual current signal, the second input channel (CI2) receives a given current signal, and the third input channel (CI3) receives an ejecting fluid pressure signal measured by the ejecting fluid pressure sensor (5). The working flow rate calculator (UC) calculates a given working flow rate signal based on the signals received by the three input channels and sends the given working flow rate signal to the third input channel (BI3) of the second controller (UB). For the working flow rate calculator (UC), the second input channel (CI2) receives the given current signal, and the required working flow rate is calculated by the second look-up table (UC2) as the feedforward quantity of the given working flow rate signal; the first input channel (CI1) receives the actual current signal, and the error between the given current signal and the actual current signal is fed back to the first PID controller as the current error compensation quantity; at the same time, the anode nominal pressure of the fuel cell corresponding to each load current is determined by the first look-up table (UC1) according to the actual current signal; the first input channel (CI3) receives the actual pressure signal, and the error between the actual pressure signal and the nominal pressure is fed back to the second PID controller as the pressure error compensation quantity; the sum of the feedforward quantity, the current error compensation quantity, and the pressure error compensation quantity is taken as the output of the working flow rate calculator (UC), i.e. the given working flow rate signal. For the working flow rate calculator (UC), the second input channel (CI2) receives the given current signal, and the required working flow rate is calculated by the second look-up table (UC2) as the feedforward quantity of the given working flow rate signal; the first input channel (CI1) receives the actual current signal, and the error between the given current signal and the actual current signal is fed back to the first PID controller as the current error compensation quantity; at the same time, the anode nominal pressure of the fuel cell corresponding to each load current is determined by the first look-up table (UC1) according to the actual current signal; the first input channel (CI3) receives the actual pressure signal, and the error between the actual pressure signal and the nominal pressure is fed back to the second PID controller as the pressure error compensation quantity; the sum of the feedforward quantity, the current error compensation quantity, and the pressure error compensation quantity is taken as the output of the working flow rate calculator (UC), i.e. the given working flow rate signal. For the working flow rate calculator (UC), the second input channel (CI2) receives the given current signal, and the required working flow rate is calculated by the second look-up table (UC2) as the feedforward quantity of the given working flow rate signal; the first input channel (CI1) receives the actual current signal, and the error between the given The working flow rate calculator (UC) comprises a first lookup table (UC1), a second lookup table (UC2), a first PID controller, and a second PID controller. The second input channel (CI2) of the working flow rate calculator (UC) is connected to the input end of the second lookup table (UC2). The difference between the signal of the second input channel (CI2) of the working flow rate calculator (UC) and the signal of the first output channel (CI1) is input to the first PID controller. The first input channel (CI1) of the working flow rate calculator (UC) is connected to the input end of the first lookup table (UC1), and the difference between the signal output by the output end of the first lookup table (UC1) and the signal of the third input channel (CI3) of the working flow rate calculator (UC) is input to the second PID controller. The signals output by the output end of the first PID controller, the output end of the second PID controller, and the output end of the second lookup table (UC2) are summed and input to the output channel (CO1) of the working flow rate calculator (UC).

2. The method of claim 1, wherein, The high-pressure hydrogen storage bottle (6) is connected to the input end of the bottle port combination valve (6a), and the output end of the bottle port combination valve (6a) is connected to the first fluid inlet (F1).

3. The method of claim 1, wherein, The proton exchange membrane fuel cell (7) comprises a cell anode (7a) and a cell cathode (7b).

4. The method of claim 1, wherein, The ejecting fluid pressure signal measured by the ejecting fluid pressure sensor (5) received by the third input channel (CI3) serves as a fuel cell anode pressure signal, and the working flow rate calculator (UC) calculates the given working flow rate signal based on the fuel cell anode pressure signal.

5. The method of claim 1, wherein, The expression of the electromagnet push rod stroke is: wherein, is the electromagnet push rod stroke, represents the function relationship between the push rod displacement and the ejector nozzle throttle area, represents the ejector nozzle throttle area.

6. The method of claim 5, wherein, The expression of the ejector nozzle throttle area is: wherein, is a given hydrogen mass flow signal calculated from the load current demand, denotes the working fluid pressure, denotes a function of the working fluid and the ejector fluid pressure ratio range representing both subsonic / sonic flow conditions of the gas at the nozzle.

7. The method of claim 6, wherein, The ratio of working fluid to ejector fluid pressure is a function of the gas subsonic / supersonic flow regime at the nozzle The expression is: wherein, represents the injection fluid pressure, represents the gas constant of hydrogen, represents the nozzle orifice flow correction coefficient, T represents the temperature, k represents the hydrogen adiabatic coefficient.

8. The method of claim 7, wherein, The nozzle throttle flow correction coefficient is related to the structure shape at the nozzle.

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