Fuel cell engine hydrogen supply system and control method thereof

Abstract

The invention relates to a fuel cell engine hydrogen supply system and a control method thereof.The fuel cell engine hydrogen supply system comprises a hydrogen storage bottle, a heat exchanger, a stop valve, a double-proportional-valve ejector assembly, an in-stack pressure sensor, a fuel cell stack and a controller which are sequentially connected in the hydrogen supply direction; the double-proportion ejector assembly comprises two sub-assemblies which are connected in parallel, one sub-assembly comprises a first proportional valve and a first ejector which are connected in series, and the other sub-assembly comprises a second proportional valve and a second ejector which are connected in series; the controller is connected with the in-pile pressure sensor and is used for performing PI closed-loop control on the first proportional valve and the second proportional valve according to the deviation between the hydrogen in-pile target pressure and the actual pressure until the hydrogen pressure is stabilized at the hydrogen in-pile target pressure; therefore, the hydrogen flow and pressure under the transient working condition can be effectively adjusted to ensure the stability of hydrogen supply, so that the service life of the proportional valve is ensured.

Description

Technical Field

[0001] The present application relates to the field of engine technology, and in particular to a fuel cell engine hydrogen supply system and a control method thereof. Background Art

[0002] Fuel cells are essentially devices that convert the chemical energy of fuel into electrical energy. As hydrogen energy has the advantages of high energy density and zero carbon, especially proton exchange membrane fuel cells (PEMFC) have the advantages of high hydrogen energy utilization, low starting temperature, long life, and zero pollution, it is widely recognized as the preferred choice for vehicle-mounted new energy power. In the fuel cell system, the hydrogen supply system is particularly critical as one of its core subsystems. With the future demand for high-power fuel cell systems, the hydrogen flow rate will inevitably increase. For a single proportional valve structure, this will lead to the need to increase the aperture parameters of the proportional valve. Under small load conditions, large-aperture proportional valves are difficult to achieve stability and accuracy of hydrogen pressure. Similarly, under large load conditions, due to the characteristics of the proportional valve, when the opening exceeds a large degree, the proportional valve is in a high duty cycle frequency range, and the hydrogen pressure at the inlet of the stack is unstable and cannot be accurately controlled.

[0003] The fuel cell dual-proportional system in the related art includes a dual-proportional valve group, a controller and a hydrogen inlet sensor, the dual-proportional valves are connected in parallel, and the first proportional valve is smaller than the second proportional valve, the controller includes a pressure difference processor, a total opening controller and a dual-proportional valve opening decomposition controller, and the dual-proportional valve system control method is to calculate the deviation between the target pressure and the actual pressure of hydrogen inlet, and transmit the deviation to the total opening controller, and the dual-proportional valve duty cycle output by the total opening controller is transmitted to the first proportional valve and the second proportional valve via the dual-proportional valve opening decomposition controller, and finally the two proportional valves are opened one by one. However, although the above scheme realizes the precise control of hydrogen pressure and flow to a certain extent and meets the high power demand, when there is a certain transient working condition, the hydrogen demand pressure makes the first proportional valve in the maximum duty cycle state and the second proportional valve switches back and forth between the open and closed states, which will cause pressure instability and reduce the service life of the proportional valve. Summary of the invention

[0004] Based on this, it is necessary to provide a fuel cell engine hydrogen supply system and a control method thereof to address the problem in the related art that the service life of the proportional valve is reduced due to unstable pressure.

[0005] In a first aspect, the present application provides a fuel cell engine hydrogen supply system, comprising:

[0006] Hydrogen storage bottles;

[0007] Heat exchangers;

[0008] Stop valve;

[0009] A dual proportional valve ejector assembly, the dual proportional ejector assembly comprising two subassemblies connected in parallel, wherein one subassembly comprises a first proportional valve and a first ejector connected in series, and the other subassembly comprises a second proportional valve and a second ejector connected in series;

[0010] Stack pressure sensor; and

[0011] Fuel cell stack;

[0012] The fuel cell engine hydrogen supply system also includes a controller, which is connected to the stack pressure sensor. The controller is used to calculate the hydrogen stack target pressure based on the target power of the fuel cell stack under the current operating conditions, and is used to receive the actual pressure from the stack pressure sensor, calculate the deviation from the hydrogen stack target pressure, and perform PI closed-loop control on the first proportional valve and the second proportional valve according to the deviation until the hydrogen pressure stabilizes at the hydrogen stack target pressure.

[0013] In one embodiment, the fuel cell engine hydrogen supply system also includes a water-hydrogen separator assembly, which is connected to the outlet end of the fuel cell stack and is used to discharge waste and assist in pressure reduction.

[0014] In one embodiment, the water hydrogen separator assembly includes:

[0015] a water-hydrogen separator connected to the outlet end of the fuel cell stack;

[0016] A water storage tank connected to the first outlet end of the water-hydrogen separator;

[0017] an exhaust valve connected to the second outlet end of the water-hydrogen separator; and

[0018] A drain valve is connected to the outlet end of the water storage tank.

[0019] In one embodiment, the fuel cell engine hydrogen supply system also includes a hydrogen circulation pump, the inlet end of the hydrogen circulation pump is connected to the third outlet end of the water-hydrogen separator, and the outlet end of the hydrogen circulation pump is connected between the second proportional valve and the second ejector.

[0020] In one embodiment, the diameter of the first proportional valve is smaller than the diameter of the second proportional valve.

[0021] In one of the embodiments, a safety valve is further included, and the safety valve is connected between the stack entry pressure sensor and the second ejector.

[0022] In a second aspect, the present application provides a control method, which is applied to any fuel cell engine hydrogen supply system provided in the first aspect, and the control method comprises the following steps:

[0023] Receive the actual pressure from the stack pressure sensor and calculate the deviation between the actual pressure and the target pressure of hydrogen entering the stack, where the target pressure of hydrogen entering the stack is obtained according to the target power under the current working conditions;

[0024] The first proportional valve and the second proportional valve are subjected to PI closed-loop control according to the deviation until the hydrogen pressure is stabilized at the target pressure for hydrogen entering the stack.

[0025] In one embodiment, performing PI closed-loop control on the first proportional valve and the second proportional valve according to the deviation includes:

[0026] Performing PI closed-loop control on the first proportional valve according to the deviation, and when the opening of the first proportional valve is not less than a preset first threshold, controlling the opening value of the first proportional valve to reach a preset maximum opening value, and performing PI closed-loop control on the second proportional valve;

[0027] When the opening degree of the first proportional valve is less than the preset first threshold value, the method returns to performing PI closed-loop control on the first proportional valve according to the deviation.

[0028] In one embodiment, performing PI closed-loop control on the second proportional valve includes:

[0029] Determine whether the opening of the second proportional valve is not greater than a preset second threshold value. If the opening of the second proportional valve is not greater than the preset second threshold value, close the second proportional valve. If the opening of the second proportional valve is greater than the preset second threshold value, return to controlling the opening value of the first proportional valve to reach the preset maximum opening value, and perform PI closed-loop control on the second proportional valve.

[0030] In one embodiment, after closing the second proportional valve, the method further comprises:

[0031] Calculate the total number of closing times of the second proportional valve within a preset time length, and determine whether the total number of closing times is not less than a preset number threshold;

[0032] When the total closing times is not less than the preset times threshold, the opening of the second proportional valve is controlled to reach the preset opening threshold, and the first proportional valve is re-controlled by PI closed loop;

[0033] When the total closing times is less than the preset times threshold, the process returns to calculating the total closing times of the second proportional valve within the preset time length, and determines whether the total closing times is not less than the preset times threshold.

[0034] The above-mentioned fuel cell engine hydrogen supply system includes a hydrogen storage bottle, a heat exchanger, a stop valve, a dual-proportional valve ejector assembly, an inlet pressure sensor, a fuel cell stack and a controller connected in sequence along the hydrogen supply direction. The dual-proportional ejector assembly includes two sub-assemblies connected in parallel, one of which includes a first proportional valve and a first ejector connected in series, and the other sub-assembly includes a second proportional valve and a second ejector connected in series; the controller is connected to the inlet pressure sensor, and the controller is used to calculate the hydrogen inlet target pressure according to the target power of the fuel cell stack under the current working conditions, and is used to receive the actual pressure from the inlet pressure sensor, calculate the deviation from the hydrogen inlet target pressure, and perform PI closed-loop control on the first proportional valve and the second proportional valve according to the deviation until the hydrogen pressure stabilizes at the hydrogen inlet target pressure. The fuel cell engine hydrogen supply system in the present application detects the deviation between the hydrogen inlet pressure and the target pressure in real time through a controller, and can effectively adjust the hydrogen flow and pressure under transient conditions through a dual proportional valve ejector assembly and a PI closed-loop control strategy, especially in the case of sudden load changes, and can timely adjust the opening of the proportional valve to ensure the stability of the hydrogen supply, that is, the stability of the gas pressure, thereby ensuring the service life of the proportional valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] FIG1 is a schematic diagram of the structure of a hydrogen supply system for a fuel cell engine in some embodiments of the present application;

[0037] FIG2 is a flow chart of a control method for a fuel cell engine hydrogen supply system in some embodiments of the present application;

[0038] FIG3 is a flow chart showing a control method for a hydrogen supply system of a fuel cell engine in other embodiments of the present application.

[0039] Description of Figure Numbers:

[0040] 101. Hydrogen storage bottle; 102. Heat exchanger; 103. Stop valve; 104. First proportional valve; 105. First ejector; 106. Second proportional valve; 107. Second ejector; 108. Stack inlet pressure sensor; 109. Fuel cell stack; 110. Water-hydrogen separator; 111. Water storage tank; 112. Exhaust valve; 113. Drain valve; 114. Hydrogen circulation pump; 115. Safety valve. DETAILED DESCRIPTION

[0041] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0042] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", "vertical", "horizontal", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0043] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0044] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances. It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there can be a intermediate element at the same time.

[0045] In order to solve the problem of reduced service life of the proportional valve due to unstable pressure in the related art, in the first aspect, referring to FIG. 1 , an embodiment of the present application provides a fuel cell engine hydrogen supply system, comprising a hydrogen storage bottle 101, a heat exchanger 102, a stop valve 103, a dual proportional valve ejector assembly, a stack pressure sensor 108, a fuel cell stack 109 and a controller connected in sequence along the hydrogen supply direction, the dual proportional ejector assembly comprising two subassemblies connected in parallel, one of which comprises a first proportional valve 104 and a first ejector 105 connected in series, and the other comprises a second proportional valve 106 and a second ejector 107 connected in series; the controller is connected to the stack pressure sensor 108, and the controller is used to calculate the hydrogen stack target pressure according to the target power of the fuel cell stack 109 under the current working condition, and to receive the actual pressure from the stack pressure sensor 108, calculate the deviation from the hydrogen stack target pressure, and perform PI closed-loop control on the first proportional valve 104 and the second proportional valve 106 according to the deviation until the hydrogen pressure stabilizes at the hydrogen stack target pressure.

[0046] Among them, PI closed-loop control is a control method mainly used to adjust the output of the system to achieve the expected target value. PI stands for proportional and integral. The basic principle is to generate a control output based on the current error, that is, the gap between the target value and the actual value. The larger the error, the stronger the control effect, so that the output value gradually approaches the target value. The openings of the first proportional valve 104 and the second proportional valve 106 are inconsistent. The small-diameter proportional valve can provide more accurate flow and pressure control at low load, while the large-diameter proportional valve can handle higher flow requirements at high load, thereby meeting the gas flow requirements under different working conditions. The arrows in Figure 1 indicate a direction from right to left, so the hydrogen supply direction in this embodiment is from right to left.

[0047] Specifically, in a fuel cell system, the control of the hydrogen inlet pressure is a typical closed-loop control scenario. The target pressure is determined by the current operating conditions, and the actual pressure is measured by the sensor and transmitted to the controller. The controller adjusts the opening of the proportional valve through the PI control strategy based on the deviation between the target pressure and the actual pressure, so that the actual pressure approaches the target pressure. In other words, through reasonable proportional gain and integral gain settings, PI closed-loop control can effectively achieve stable and rapid adjustment to ensure the dynamic performance and steady-state accuracy of the system.

[0048] The fuel cell engine hydrogen supply system in this embodiment detects the deviation between the hydrogen inlet pressure and the target pressure in real time through the controller, and can effectively adjust the hydrogen flow and pressure under transient conditions through the dual proportional valve ejector assembly and the PI closed-loop control strategy. Especially in the case of sudden load changes, the opening of the proportional valve can be adjusted in time to ensure the stability of the hydrogen supply, that is, the stability of the gas pressure, thereby ensuring the service life of the proportional valve.

[0049] 1 , in some embodiments, the fuel cell engine hydrogen supply system further includes a water-hydrogen separator 110 assembly, which is connected to the outlet end of the fuel cell stack 109 and is used to discharge waste and assist in pressure reduction.

[0050] Specifically, during the power generation process, the fuel cell stack 109 not only generates electricity and water, but also produces some unreacted hydrogen, nitrogen and a small amount of other gases. The water-hydrogen separator 110 assembly can effectively discharge these waste gases to ensure the clean and stable operation of the system, and help reduce the waste of unreacted hydrogen, improve fuel utilization, and thus improve the overall operating efficiency of the system.

[0051] 1 , in some embodiments, the water-hydrogen separator 110 assembly includes a water-hydrogen separator 110, a water storage tank 111, an exhaust valve 112 and a drain valve 113, the water-hydrogen separator 110 is connected to the outlet end of the fuel cell stack 109; the water storage tank 111 is connected to the first outlet end of the water-hydrogen separator 110; the exhaust valve 112 is connected to the second outlet end of the water-hydrogen separator 110; and the drain valve 113 is connected to the outlet end of the water storage tank 111.

[0052] Specifically, the combination of the water hydrogen separator 110, the water storage tank 111, the exhaust valve 112 and the drain valve 113 forms a complete water hydrogen management system, ensuring the safe and efficient operation of the fuel cell. The advantages of the various components after coordination not only improve the performance and safety of the system, but also optimize the utilization of resources, reduce the frequency of shutdown maintenance, and help improve the economy and sustainability of the entire fuel cell system.

[0053] Referring to the figure, in some embodiments, the fuel cell engine hydrogen supply system also includes a hydrogen circulation pump 114, the inlet end of the hydrogen circulation pump 114 is connected to the third outlet end of the water-hydrogen separator 110, and the outlet end of the hydrogen circulation pump 114 is connected between the second proportional valve 106 and the second ejector 107.

[0054] Among them, the setting of the hydrogen circulation pump 114 significantly improves the circulation efficiency of hydrogen and further reduces the pressure instability caused by frequent opening and closing. When using a traditional single proportional valve, pressure fluctuations caused by changes in hydrogen demand may occur, and the circulation pump can keep the flow and pressure of hydrogen in the system uniform, fundamentally improving the response speed of the system. In addition, due to the setting of the first proportional valve 104 and the second proportional valve 106, and matching a suitable ejector, the full power range can be covered, and the hydrogen circulation effect is good. If the cost is considered, the hydrogen circulation pump 114 may not be added.

[0055] 1 , in some embodiments, the diameter of the first proportional valve 104 is smaller than the diameter of the second proportional valve 106 .

[0056] Specifically, setting the caliber of the first proportional valve 104 to be smaller than the caliber of the second proportional valve 106 can provide finer adjustment capabilities in low-flow and high-precision control scenarios. When precise flow control is required, the small-caliber proportional valve can provide higher accuracy and avoid system fluctuations caused by excessive or small flow. In addition, the small-caliber first proportional valve 104 can reduce pressure loss under low-flow working conditions and keep the pressure in the system relatively stable, thereby avoiding problems caused by local high or low pressure.

[0057] 1 , in some embodiments, the fuel cell engine hydrogen supply system further includes a safety valve 115 , which is connected between the stack pressure sensor 108 and the second ejector 107 .

[0058] Specifically, the main function of the safety valve 115 is to open automatically when the system pressure exceeds the set value to release excess gas, thereby reducing the pressure in the system, thereby preventing the hydrogen supply system from being damaged or malfunctioning due to overpressure, and improving the stability and safety of the system operation.

[0059] In a second aspect, an embodiment of the present application provides a control method, which is applied to any one of the fuel cell engine hydrogen supply systems provided in the first aspect (as shown in FIG. 1 ), and the control method comprises the following steps:

[0060] Receive the actual pressure from the stack pressure sensor and calculate the deviation between the actual pressure and the target pressure of hydrogen entering the stack, where the target pressure of hydrogen entering the stack is obtained according to the target power under the current working conditions;

[0061] The first proportional valve and the second proportional valve are subjected to PI closed-loop control according to the deviation until the hydrogen pressure is stabilized at the target pressure for hydrogen entering the stack.

[0062] Among them, the target power refers to the electricity that the fuel cell needs to output under specific working conditions, and the target pressure of hydrogen entering the stack can be calculated based on the hydrogen flow rate and the gas state equation.

[0063] Specifically, the first proportional valve is controlled by PI closed loop according to the target pressure of hydrogen entering the stack and the actual pressure of hydrogen entering the stack until the hydrogen pressure stabilizes at the target pressure. The PI closed loop control is the duty cycle of the first proportional valve obtained according to the hydrogen pressure deviation, the proportional coefficient and the integral action coefficient. The second proportional valve is similar, as shown in the formula:

[0064] ;

[0065] Where, u represents the proportional valve control duty cycle; k p Indicates the proportionality coefficient; k i represents the integral action coefficient; dt represents the time parameter; e represents the deviation between the target pressure and the actual pressure of hydrogen entering the stack, e=P dmd -P act , P dmd Indicates the target pressure of hydrogen entering the reactor, P act Indicates the actual pressure of hydrogen entering the reactor.

[0066] In some embodiments, performing PI closed-loop control on the first proportional valve and the second proportional valve according to the deviation includes:

[0067] Performing PI closed-loop control on the first proportional valve according to the deviation, and when the opening of the first proportional valve is not less than a preset first threshold, controlling the opening value of the first proportional valve to reach a preset maximum opening value, and performing PI closed-loop control on the second proportional valve;

[0068] When the opening degree of the first proportional valve is less than the preset first threshold value, the method returns to performing PI closed-loop control on the first proportional valve according to the deviation.

[0069] The setting of the preset first threshold is based on the working characteristics and control requirements of the system. The preset first threshold may be the minimum opening value that meets the basic flow requirements of the system. In the fuel cell system, this threshold may correspond to the initial hydrogen flow required at startup or low power output. In addition, the preset first threshold is less than the maximum opening value to ensure the safety and stability of the system during operation.

[0070] Specifically, when the opening of the first proportional valve is not less than a preset first threshold, the opening of the first proportional valve and the second proportional valve can be dynamically adjusted using PI closed-loop control, so that the system can efficiently utilize fuel or gas resources and avoid unnecessary waste.

[0071] In some embodiments, performing PI closed-loop control on the second proportional valve includes:

[0072] Determine whether the opening of the second proportional valve is not greater than a preset second threshold value. If the opening of the second proportional valve is not greater than the preset second threshold value, close the second proportional valve. If the opening of the second proportional valve is greater than the preset second threshold value, return to controlling the opening value of the first proportional valve to reach the preset maximum opening value, and perform PI closed-loop control on the second proportional valve.

[0073] Among them, the setting of the preset second threshold is based on the working characteristics and control requirements of the system. The second threshold of the second proportional valve is usually set to an opening value that meets the maximum flow requirement of the system. For example, in a fuel cell system, this threshold may correspond to the maximum hydrogen flow required for high power output.

[0074] Specifically, when the opening of the second proportional valve is not greater than the preset second threshold value, closing the valve can avoid unnecessary flow output, optimize the use of system resources, and reduce energy waste; in addition, by dynamically adjusting the opening of the first proportional valve and the second proportional valve, the system can achieve efficient flow and pressure control under different working conditions and improve overall operating efficiency; in addition, when the valve reaches the maximum opening, the system will close the second proportional valve to avoid the risk of leakage due to excessive flow, especially in high pressure or dangerous environments, thereby ensuring the service life of the proportional valve.

[0075] In some embodiments, after closing the second proportional valve, the control method further includes:

[0076] Calculate the total number of closing times of the second proportional valve within a preset time length, and determine whether the total number of closing times is not less than a preset number threshold;

[0077] When the total closing times is not less than the preset times threshold, the opening of the second proportional valve is controlled to reach the preset opening threshold, and the first proportional valve is re-controlled by PI closed loop;

[0078] When the total closing times is less than the preset times threshold, the process returns to calculating the total closing times of the second proportional valve within the preset time length, and determines whether the total closing times is not less than the preset times threshold.

[0079] Among them, since the regular opening of the exhaust valve will lead to an increase in the duty cycle of the proportional valve to compensate for the lack of hydrogen inlet pressure, at this time, even under the condition of unchanged target power, the exhaust valve will still cause the second proportional valve to be opened repeatedly, thereby affecting the life and stability. Therefore, when the present embodiment switches from a state where both the dual proportional valves are working to a state where the first proportional valve is working alone, in order to avoid frequent closing of the second proportional valve, a method for judging the number of times the second proportional valve is closed is added.

[0080] Specifically, by presetting a threshold value, the number of times the valve is opened and closed within a certain period of time can be limited, which can effectively reduce valve wear and extend its service life. In addition, by re-performing PI closed-loop control after the number of valve closing times reaches the preset threshold, the valve opening can be adjusted more accurately, thereby improving the control accuracy and response speed of the system.

[0081] 2 , in a detailed embodiment, a method for controlling a fuel cell engine hydrogen supply system includes the following steps:

[0082] Step 201, obtaining hydrogen inlet pressure according to target power;

[0083] Step 202, the controller calculates the deviation between the hydrogen inlet pressure and the actual pressure;

[0084] Step 203, close-loop control of the first proportional valve to continuously reduce the deviation between the hydrogen inlet pressure and the target pressure. When the actual pressure does not reach the target pressure, the opening of the first proportional valve continues to increase, and step 204 is executed;

[0085] Step 204, determine the opening degree X of the first proportional valve 1 Is it not less than the first threshold value Xa? 1 ≥Xa, the shift exchange is triggered, wherein the first threshold value Xa can be set to any opening value close to 100%. At this time, the first proportional valve has output the maximum allowable opening but still cannot reach the target pressure, and step 205 needs to be executed; otherwise, at Xa 1 <Xa, return to step 203;

[0086] Step 205, the first proportional valve outputs the maximum allowable opening, and closes the loop to control the second proportional valve until the actual pressure of hydrogen entering the reactor is equal to the target pressure;

[0087] Step 206: When the target pressure decreases continuously, the opening of the second proportional valve decreases gradually, and the opening of the second proportional valve is determined. 2 Is it not less than the second threshold value X? b , in X 1 ≤X b In the case of, cancel the trigger shift exchange, and execute step 207, wherein X b It can be set to any opening value close to 0%; otherwise, return to step 205;

[0088] Step 207, closing the second proportional valve, and the controller calculates the number of times the second proportional valve is closed within a time period of T;

[0089] Step 208, determine whether the number of times N that the second proportional valve is closed within time T is not less than N b , when N ≥ N bIn the case of, step 209 is executed, wherein N b The value of varies with the power of the fuel-electric system; otherwise, when N<N b In the case of , return to step 207;

[0090] Step 209: the second proportional valve outputs an opening X Nb (preset calibration amount) and close the loop to control the first proportional valve.

[0091] Preferably, referring to FIG. 3 , in another detailed embodiment, the control method of the fuel cell engine hydrogen supply system is based on the above control method, except that the optimized control method adds a judgment of a high power limit state, and executes different dual proportional valve control methods based on the judgment result, that is, the maximum opening of the dual proportional valve is limited by the high power limit mode to avoid a high duty cycle of the proportional valve. The specific steps of the method are as follows:

[0092] Step 301, obtaining the hydrogen inlet pressure according to the target power;

[0093] Step 302, the controller calculates the deviation between the target pressure of hydrogen entering the stack and the actual pressure;

[0094] Step 303, close-loop control of the first proportional valve to continuously reduce the deviation between the actual pressure of hydrogen entering the reactor and the target pressure;

[0095] Step 304, determining whether to enter the high power limit mode, if it has entered the high power limit mode, executing step 305, wherein when the fuel cell system receives the high power limit mode instruction, it is determined to enter the high power limit mode; otherwise, executing step 311;

[0096] Step 305: Determine the opening degree X of the first ratio 1 Is it not less than the preset third threshold value Xa? 1 , in X 1 ≥Xa 1 In the case of a shift exchange, the shift exchange is triggered and step 306 is executed, wherein a third threshold value Xa is preset. 1 It is necessary to refer to the specific design and experience of the proportional valve; otherwise, 1 <Xa 1 In the case of , return to step 303;

[0097] Step 306: The first proportional valve outputs a preset opening and closes the loop to control the second proportional valve. At this time, the second proportional valve is controlled by PI close loop according to the deviation between the target pressure and the actual pressure of hydrogen entering the stack, until the actual pressure of hydrogen entering the stack is equal to the target pressure. When the target pressure decreases continuously, the opening of the second proportional valve gradually decreases, and step 307 needs to be executed.

[0098] Step 307, determine the opening degree X of the second proportional valve 2 Is it not less than the second threshold value X? b1 , in X 1 ≤X b1 In the case of X, cancel the trigger shift exchange and execute step 308; otherwise, 1 >X b1 In the case of , return to step 306;

[0099] Step 308, closing the second proportional valve, and the controller calculates the number of times the second proportional valve is closed within a time period of T;

[0100] Step 309, determine whether the number of times N that the second proportional valve is closed within time T is not less than N b , when N ≥ N b If the condition is , execute step 310; otherwise, return to step 308;

[0101] Step 310: the second proportional valve outputs an opening X Nb (preset calibration quantity), and close-loop control the first proportional valve. At this time, only PI closed-loop control of the first proportional valve is required. When the current operating conditions change, it is necessary to return to step 303 to continue controlling the hydrogen inlet pressure.

[0102] Step 311, determine the opening degree X of the first proportional valve 1 Is it not less than the first threshold value Xa? 1 ≥Xa, execute step 312; otherwise, return to step 303;

[0103] Step 312, the first proportional valve outputs the maximum allowable opening, and closes the loop to control the second proportional valve;

[0104] Step 313, determine the opening degree X of the second proportional valve 2 Is it not less than the second threshold value X? b , in X 1 ≤X b If yes, execute step 308; otherwise, return to step 312.

[0105] In summary, after the introduction of the dual proportional valve ejector assembly and the hydrogen circulation pump, the fuel cell engine hydrogen supply system of the present application can effectively avoid the risk of poor hydrogen circulation effect. The control method provided for the fuel cell engine hydrogen supply system describes in detail the control method of opening and closing the dual proportional valves in the form of shift exchange one by one, and by counting the number of times the second proportional valve is closed within a period of time, it can effectively solve the problems of unstable hydrogen pressure and shortened life caused by frequent switching of the second proportional valve under certain transient conditions. In addition, the proposed optimization control method adds a judgment on whether to adopt a high power limit mode. When high power is not required within a certain period of time, the opening of the two proportional valves can be limited to a preset opening, thereby avoiding the use of a high duty cycle of the proportional valve, thereby improving the stability and accuracy of the hydrogen pressure.

[0106] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0107] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0108] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A fuel cell engine hydrogen supply system, characterized in that: The fuel cell engine hydrogen supply system comprises: Hydrogen storage bottles; Heat exchangers; Stop valve; A dual proportional valve ejector assembly, the dual proportional ejector assembly comprising two subassemblies connected in parallel, wherein one of the subassemblies comprises a first proportional valve and a first ejector connected in series, and the other subassembly comprises a second proportional valve and a second ejector connected in series; Stack pressure sensor; and Fuel cell stack; The fuel cell engine hydrogen supply system also includes a controller, which is connected to the stack entry pressure sensor. The controller is used to calculate the hydrogen stack entry target pressure according to the target power of the fuel cell stack under the current operating conditions, and is used to receive the actual pressure from the stack entry pressure sensor, calculate the deviation from the hydrogen stack entry target pressure, and perform PI closed-loop control on the first proportional valve and the second proportional valve according to the deviation until the hydrogen pressure is stabilized at the hydrogen stack entry target pressure.

2. The fuel cell engine hydrogen supply system according to claim 1, characterized in that: The fuel cell engine hydrogen supply system also includes a water-hydrogen separator assembly, which is connected to the outlet end of the fuel cell stack and is used to discharge waste and assist in pressure reduction.

3. The fuel cell engine hydrogen supply system according to claim 2, characterized in that: The water-hydrogen separator assembly comprises: a water-hydrogen separator connected to the outlet end of the fuel cell stack; A water storage tank connected to the first outlet end of the water-hydrogen separator; an exhaust valve connected to the second outlet end of the water-hydrogen separator; and A drain valve is connected to the outlet end of the water storage tank.

4. The fuel cell engine hydrogen supply system according to claim 3, characterized in that: The fuel cell engine hydrogen supply system also includes a hydrogen circulation pump, the inlet end of the hydrogen circulation pump is connected to the third outlet end of the water-hydrogen separator, and the outlet end of the hydrogen circulation pump is connected between the second proportional valve and the second ejector.

5. The fuel cell engine hydrogen supply system according to claim 1, characterized in that: The diameter of the first proportional valve is smaller than that of the second proportional valve.

6. The fuel cell engine hydrogen supply system according to claim 1, characterized in that: The system further includes a safety valve connected between the stack entry pressure sensor and the second ejector.

7. A control method, applicable to the hydrogen supply system of a fuel cell engine according to any one of claims 1 to 6, characterized in that: The control method comprises the following steps: receiving an actual pressure from a stack entry pressure sensor, and calculating a deviation between the actual pressure and a target pressure of hydrogen gas entering the stack, wherein the target pressure of hydrogen gas entering the stack is obtained according to a target power under a current operating condition; The first proportional valve and the second proportional valve are subjected to PI closed-loop control according to the deviation until the hydrogen pressure is stabilized at the hydrogen inlet target pressure.

8. The control method according to claim 7, characterized in that: The performing PI closed-loop control on the first proportional valve and the second proportional valve according to the deviation comprises: Performing PI closed-loop control on the first proportional valve according to the deviation, and when the opening of the first proportional valve is not less than a preset first threshold, controlling the opening value of the first proportional valve to reach a preset maximum opening value, and performing PI closed-loop control on the second proportional valve; When the opening degree of the first proportional valve is smaller than the preset first threshold, the process returns to the PI closed-loop control of the first proportional valve according to the deviation.

9. The control method according to claim 8, characterized in that: The performing PI closed-loop control on the second proportional valve comprises: Determine whether the opening of the second proportional valve is not greater than a preset second threshold value, and if the opening of the second proportional valve is not greater than the preset second threshold value, close the second proportional valve; if the opening of the second proportional valve is greater than the preset second threshold value, return to the control of the opening value of the first proportional valve to reach a preset maximum opening value, and perform PI closed-loop control on the second proportional valve.

10. The control method according to claim 9, characterized in that: After closing the second proportional valve, the method further includes: Calculating the total number of closing times of the second proportional valve within a preset time period, and determining whether the total number of closing times is not less than a preset number threshold; When the total closing times is not less than the preset times threshold, controlling the opening of the second proportional valve to reach the preset opening threshold, and re-performing PI closed-loop control on the first proportional valve; When the total closing times is less than the preset times threshold, the method returns to the step of calculating the total closing times of the second proportional valve within the preset time length, and determines whether the total closing times is not less than the preset times threshold.

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