Fuel cell variable injection flow off-line model control device

Abstract

The invention discloses a fuel cell variable injection flow off-line model control device which is characterized in that in the working process of the device, when a fuel cell system finishes starting and enters a running state, a target current is firstly calculated according to a required power instruction received by a fuel cell system FCU and a current stack voltage; meanwhile, the fuel cell system FCU checks single deviation data of the blind end of the electric pile and makes correction judgment; and looking up a table according to the target current obtained in the previous step to obtain a target injection flow, summing the target injection flow with a single deviation correction value, outputting a correction injection flow, and carrying out deviation and comparison on the value and an injection flow actual value obtained subsequently, namely, carrying out closed-loop control, and outputting an injection flow correction value. The device can dynamically adjust the injection flow, so that the service life of a fuel cell system is prolonged; compared with a control process of adding a sensor, the cost is reduced, and the reliability of the fuel cell system is improved.

Description

Technical Field

[0001] The invention relates to the technical field of fuel cells, and in particular to an off-line model control device for a fuel cell with a variable injection flow rate. Background Art

[0002] As a new type of energy device, the fuel cell system has the characteristics of zero emission, high power density, outstanding energy conversion efficiency, strong low-temperature start-up capability, and excellent reliability, and is increasingly valued by companies and research institutions in various countries. The fuel cell system converts the chemical energy in hydrogen fuel into electrical energy through the electrochemical reaction of hydrogen and oxygen. While generating electricity and releasing heat, a certain amount of water will be generated on the cathode side of the fuel cell. Due to the characteristics of proton exchange membrane fuel cells, both the positive and negative electrodes need to maintain appropriate humidity. Based on the research on water management, people hope that the water in the membrane and on both sides of the positive and negative electrodes can be evenly distributed, which is conducive to improving battery performance, working stability and durability. However, in fact, since the water generated by the chemical reaction is at the cathode, the cathode is always richer in water than the anode. Therefore, without the use of external humidification, the anode hydrogen circulation method is usually used to achieve self-humidification. The traditional solution is to use a hydrogen circulation pump or an ejector, but the former is large in size and has parasitic power consumption, while the latter is small in size, light in weight, and highly reliable, but the ejection flow rate is generally not adjustable.

[0003] At present, the hydrogen circulation pump is more commonly used for the hydrogen circulation of fuel cell anodes, while the ejector is relatively rare. Even though it has the advantages of small size, low cost and high reliability, its disadvantages of small ejector flow coverage and passive flow regulation cannot be ignored.

[0004] With the advancement of technology, dual-injection solutions and single-injection variable-section solutions have gradually emerged to solve the problem of small injection flow coverage. However, due to the lack of dynamic monitoring of the flow, it is impossible to perform real-time calculation, adjustment and correction according to the current operating status of the fuel cell stack, and there is a lack of closed-loop control means.

[0005] To ensure that the fuel cell is in the best hydrothermal management state, the anode hydrogen injection flow rate is not the larger the better. With the changes in ambient temperature, coolant temperature, cathode air flow, pressure and humidity, as well as the cumulative operating time of the fuel cell under a certain working condition, the hydrogen injection flow rate should be changed accordingly, but if the injection flow rate feedback value is not obtained, it is obviously difficult to make quantitative adjustments. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention discloses a fuel cell variable ejection flow rate offline model control device, comprising: a high-pressure hydrogen source, the output end of the high-pressure hydrogen source is connected to a double ejector, one output end of the double ejector is connected to a hydrogen heater, the output end of the hydrogen heater is connected to a hydrogen humidifier, the output end of the hydrogen humidifier is connected to a simulated fuel cell stack, the output end of the simulated fuel cell stack is connected to a water separator, and the output end of the water separator is connected to the input end of the double ejector;

[0007] A hydrogen consumption flowmeter is provided on the connecting pipeline between the high-pressure hydrogen source and the double ejector, a temperature sensor T3, a pressure sensor P3 and a hydrogen humidity sensor H1 are provided on the connecting pipeline between the hydrogen humidifier and the simulated fuel cell, a temperature sensor T2 and a pressure sensor P2 are provided on the connecting pipeline between the simulated fuel cell and the water separator, a hydrogen circulation flowmeter and a flow resistance regulating valve are provided on the connecting pipeline between the water separator and the double ejector, and a temperature sensor T1 and a pressure sensor P1 are also provided, and a simulated hydrogen consumption valve is provided on the output pipeline between the simulated fuel cell and the atmosphere;

[0008] Based on the data information collected by pressure sensor P1, pressure sensor P2, pressure sensor P3 and hydrogen consumption flow meter, the pressure before and after the fuel cell stack and the hydrogen consumption information are determined by adjusting the simulated stack, simulated hydrogen consumption valve and flow resistance regulating valve;

[0009] Based on the data information detected by the temperature sensor T1 , the temperature sensor T2 , the temperature sensor T3 and the hydrogen humidity sensor H1 , the hydrogen heater and the hydrogen humidifier are controlled to adjust the boundary range value of the test system.

[0010] The double ejector comprises a hydrogen inlet, a stack inlet, a hydrogen return inlet, a proportional valve 1 and a proportional valve 2, wherein the output end of the hydrogen consumption flowmeter is connected to the hydrogen inlet, the stack inlet is connected to the input end of the hydrogen heater, and the hydrogen return inlet is connected to the output end of the flow resistance regulating valve, wherein fresh hydrogen enters the double ejector from the hydrogen inlet, mixes with the mixed cycle hydrogen entering from the hydrogen return inlet, and enters the fuel cell stack from the stack inlet, wherein the hydrogen output by the fuel cell stack enters the hydrogen return inlet; when high-pressure hydrogen enters the double ejector, it passes through the proportional valve 1 and the proportional valve 2 and the hydrogen supply channel in which they are located in turn, with the hydrogen inlet pressure as the target, the proportional valve 1 is used for steady-state control, and the proportional valve 2 is used for dynamic adjustment, a double ejector flow calculation model is generated by data fitting, the duty cycle of the proportional valve 1 is obtained by the model, and the fuel cell system dynamically adjusts the duty cycle of the proportional valve 2 based on the current hydrogen inlet pressure demand.

[0011] According to the hydrogen operating conditions of the fuel cell under different working conditions, the offline calibration model is output according to the duty cycle of proportional valve 1 and proportional valve 2, the current hydrogen inlet pressure and temperature information, and the actual value of the current dual injection flow rate is output, compared with the corrected injection flow rate, and the deviation is summed and output as a correction value, ultimately achieving dynamic closed-loop control.

[0012] The simulated hydrogen consumption valve monitors the pressure difference between the pressure sensor P3 and the pressure sensor P2, and the output parameters of the hydrogen consumption flowmeter, so as to simulate the hydrogen consumption of the fuel cell under different working conditions. The flow resistance regulating valve realizes the actual flow resistance of the simulated pipeline by controlling the target feedback value of the pressure sensor P1.

[0013] The water separator integrates the internal water and hydrogen discharge solenoid valve, separates the liquid water of the entire device through the centrifugal impact water separation structure, and simulates the actual operation state of the fuel cell system by controlling the switching frequency of the solenoid valve, while protecting the working process of the hydrogen circulation flow meter.

[0014] When the deviation of the blind-end cell of the stack is greater than the set threshold, the difference between the deviation value and the set threshold is converted and output as a corresponding correction value. The sum of the correction value and the target injection flow rate is used as part of the input value of the dual injection flow calculation model at this stage.

[0015] The deviation between the corrected ejection flow rate and the actual flow rate is compared, and the difference obtained and the corrected ejection flow rate are summed as the final input value of the double ejection flow calculation model.

[0016] A fuel cell variable injection flow offline model control device, the control method of the device is as follows:

[0017] S1, the fuel cell system starts and enters the operating state;

[0018] S2. Calculate the target current based on the required power and the current stack voltage, and check the single-cell deviation value at the blind end of the stack at the same time;

[0019] S3, according to the target current, the target induced flow rate value is obtained by looking up the table, and the flow rate correction value is obtained according to the monomer deviation value. The two are summed to obtain the corrected induced flow rate as the calculation input value;

[0020] S4, after summing up the secondary correction of the corrected ejection flow and the comparison flow deviation, input the final value into the double ejection flow calculation model, and output a duty cycle of the proportional valve;

[0021] S5. According to the control target of hydrogen inlet pressure under the current working condition, dynamically adjust the proportional valve 2 and output the duty ratio of the proportional valve 2;

[0022] S6. Use the offline calibration model to obtain the input value of the duty cycle of proportional valve 1 and proportional valve 2. At the same time, according to the current hydrogen inlet pressure and temperature information, output the current actual value of the dual injection flow rate, and return the data at the same time. Compare the corrected injection flow rate in S3 for secondary correction, so that the duty cycle of proportional valve 1 and proportional valve 2 can be dynamically adjusted in a closed loop.

[0023] Due to the adoption of the above-mentioned technical scheme, the present invention provides a fuel cell variable injection flow offline model control device, which can realize online monitoring and closed-loop control of the injection flow without changing the structural design of the fuel cell system adopting a dual injection route, and without adding sensors and related hardware; the device can dynamically adjust the injection flow, and make timely adjustments according to the current health status of the fuel cell stack, so as to ensure the stable operation of the fuel cell system and extend the service life of the fuel cell system; compared with the control process of adding sensors, the present invention reduces costs and improves the reliability of the fuel cell system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is a structural diagram of the off-line model control device for variable injection flow of a fuel cell according to the present invention;

[0026] Figure 2 It is a working principle diagram of the variable injection flow rate off-line model control device for a fuel cell of the present invention;

[0027] Figure 3 It is a specific structural diagram of the double ejector of the present invention. DETAILED DESCRIPTION

[0028] In order to make the technical solutions and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention:

[0029] like Figure 1A fuel cell variable ejection flow offline model control device is shown. During the operation of the device, the fuel cell system completes startup and enters the operating state. At the same time, the target current is first calculated based on the required power instruction received by the fuel cell system FCU and the current stack voltage. At the same time, the fuel cell system FCU checks the blind-end cell deviation data of the stack and makes a correction judgment; the target ejection flow is obtained by looking up the table according to the target current obtained in the previous step, and after summing it with the cell deviation correction value, the corrected ejection flow is output. This value is deviated and compared with the actual value of the ejection flow obtained subsequently, that is, closed-loop control, and the ejection flow correction value is output. After the dual-injection flow calculation model obtains the flow value input, it calculates and outputs the duty cycle of proportional valve one. At this time, the fuel cell system FCU dynamically adjusts the duty cycle of proportional valve two based on the duty cycle of proportional valve one and the hydrogen inlet pressure as the control target. At the same time, the duty cycles of proportional valves one and two are output to the offline calibration model in real time. Based on the current hydrogen inlet pressure and temperature information, the offline calibration model outputs the actual value of the current dual-injection flow through a multi-dimensional table lookup. This value is dynamically closed-loop with the corrected injection flow value and outputs the corrected value. The program runs back and forth in this way.

[0030] The variable ejection flow rate offline model testing device includes a high-pressure hydrogen source 1, wherein the output end of the high-pressure hydrogen source 1 is connected to a double ejector 2, one output end of the double ejector 2 is connected to a hydrogen heater 3, the output end of the hydrogen heater 3 is connected to a hydrogen humidifier 4, the output end of the hydrogen humidifier 4 is connected to a simulated fuel cell 5, the output end of the simulated fuel cell 5 is connected to a water separator 7, and the output end of the water separator 7 is connected to the input end of the double ejector 2. A hydrogen consumption flowmeter 10 is arranged on the connecting pipeline between the high-pressure hydrogen source 1 and the double ejector 2, a temperature sensor T3, a pressure sensor P3 and a hydrogen humidity sensor H1 are arranged on the connecting pipeline between the hydrogen humidifier 4 and the simulated fuel cell 5, a temperature sensor T2 and a pressure sensor P2 are arranged on the connecting pipeline between the simulated fuel cell 5 and the water separator 7, a hydrogen circulation flowmeter 8 and a flow resistance regulating valve 9 are arranged on the connecting pipeline between the water separator 7 and the double ejector 2, and a temperature sensor T1 and a pressure sensor P1 are also arranged, and a simulated hydrogen consumption valve 6 is arranged on the output pipeline between the simulated fuel cell 5 and the atmosphere end.

[0031] Based on the data information collected by the pressure sensor P1, the pressure sensor P2, the pressure sensor P3 and the hydrogen consumption flow meter 10, the pressure before and after the fuel cell stack and the hydrogen consumption information are determined by adjusting the simulated stack 5, the simulated hydrogen consumption valve 6 and the flow resistance regulating valve 10;

[0032] Based on the data information detected by the temperature sensor T1 , the temperature sensor T2 , the temperature sensor T3 and the hydrogen humidity sensor H1 , the hydrogen heater 3 and the hydrogen humidifier 4 are controlled to adjust the boundary range value of the test system.

[0033] Further, such as Figure 3 As shown, the double ejector 2 includes a hydrogen inlet, a stack inlet, a hydrogen return inlet, a proportional valve 1 and a proportional valve 2, wherein the output end of the hydrogen consumption flowmeter 10 is connected to the hydrogen inlet, the stack inlet is connected to the input end of the hydrogen heater 3, and the hydrogen return inlet is connected to the output end of the flow resistance regulating valve 9, wherein fresh hydrogen enters the double ejector 2 from the hydrogen inlet, mixes with the mixed cycle hydrogen entering from the hydrogen return inlet, and enters the fuel cell stack from the stack inlet, wherein the hydrogen output by the fuel cell stack enters the hydrogen return inlet; when the high-pressure hydrogen enters the double ejector 2, it passes through the proportional valve 1 and the proportional valve 2 and the hydrogen supply channel where they are located in turn, and the proportional valve 1 is used for steady-state control and the proportional valve 2 is used for dynamic adjustment with the hydrogen inlet pressure as the target, and a double ejector flow calculation model is generated by data fitting, and the duty cycle of the proportional valve 1 is obtained by the model, and the fuel cell system dynamically adjusts the duty cycle of the proportional valve 2 based on the current hydrogen inlet pressure demand.

[0034] Furthermore, the simulated hydrogen consumption valve 6 monitors the pressure difference between the pressure sensor P3 and the pressure sensor P2, and the output parameters of the hydrogen consumption flowmeter 10, so as to simulate the hydrogen consumption of the fuel cell under different working conditions. The flow resistance regulating valve 9 realizes the actual flow resistance of the simulated pipeline by controlling the target feedback value of the pressure sensor P1.

[0035] Furthermore, the water separator 7 integrates the water and hydrogen discharge solenoid valve therein, and separates the liquid water of the entire device through the centrifugal impact water separation structure. By controlling the switching frequency of the solenoid valve, the actual operating state of the fuel cell system is simulated, and at the same time, the working process of the hydrogen circulation flowmeter 8 is protected.

[0036] After the fuel cell system is started up, the state jumps to operation. The fuel cell system FCU receives the required power instruction, obtains the target current through internal calculation, and obtains the target injection flow based on the current table lookup. The injection flow is summed with the correction value calculated based on the stack cell deviation, and the corrected injection flow is output. It should be added that when the cell deviation does not exceed the set limit, the injection flow correction value based on the cell deviation is zero, that is, the target injection flow is equal to the corrected injection flow.

[0037] After the secondary correction calculation, the corrected injection flow is input into the double injection flow calculation model, and the duty cycle of proportional valve one is output. This duty cycle and the current hydrogen inlet temperature and pressure conditions are used as the input of the offline calibration model. At the same time, the duty cycle of proportional valve one is used as the basic value for the control of proportional valve two, and the hydrogen inlet pressure is used as the control target value. The two work together to ensure that both the hydrogen supply demand and the internal circulation demand are met at the same time.

[0038] The duty cycle of proportional valve 1 and proportional valve 2, as well as the current hydrogen inlet pressure and hydrogen inlet temperature are the input values ​​of the offline calibration model, which outputs the model value of the current double injection flow, that is, the actual value in the control model. The actual value is compared with the corrected injection flow model for deviation, and the correction value is output according to the deviation. In this process, if the deviation is too small, the correction value is output as zero, avoiding the occurrence of unstable control.

[0039] like Figure 2 As shown, a control method of a fuel cell variable injection flow offline model control device is as follows:

[0040] S1, the fuel cell system starts and enters the operating state;

[0041] S2. Calculate the target current based on the required power and the current stack voltage, and check the single-cell deviation value at the blind end of the stack at the same time;

[0042] S3, according to the target current, the target induced flow rate value is obtained by looking up the table, and the flow rate correction value is obtained according to the monomer deviation value. The two are summed to obtain the corrected induced flow rate as the calculation input value;

[0043] S4, after summing up the secondary correction of the corrected ejection flow and the comparison flow deviation, input the final value into the double ejection flow calculation model, and output a duty cycle of the proportional valve;

[0044] S5. According to the control target of hydrogen inlet pressure under the current working condition, dynamically adjust the proportional valve 2 and output the duty ratio of the proportional valve 2;

[0045] S6. Use the offline calibration model to obtain the input value of the duty cycle of proportional valve 1 and proportional valve 2. At the same time, according to the current hydrogen inlet pressure and temperature information, output the current actual value of the dual injection flow rate, and return the data at the same time. Compare the corrected injection flow rate in S3 for secondary correction, so that the duty cycle of proportional valve 1 and proportional valve 2 can be dynamically adjusted in a closed loop.

[0046] Furthermore, the hydrogen circulation flowmeter 8 and the hydrogen consumption flowmeter 10 are volume or mass flowmeters capable of realizing online measurement of hydrogen flow. The normal working range of the hydrogen circulation flowmeter 8 is (0-400) kPaA, and the normal working range of the hydrogen consumption flowmeter 10 is (1000-2000) kPaA.

[0047] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A fuel cell variable injection flow offline model control device, characterized in that include: A high-pressure hydrogen source (1), wherein an output end of the high-pressure hydrogen source (1) is connected to a double ejector (2), an output end of the double ejector (2) is connected to a hydrogen heater (3), an output end of the hydrogen heater (3) is connected to a hydrogen humidifier (4), an output end of the hydrogen humidifier (4) is connected to a simulated battery stack (5), an output end of the simulated battery stack (5) is connected to a water separator (7), and an output end of the water separator (7) is connected to an input end of the double ejector (2); A hydrogen consumption flowmeter (10) is provided on the connecting pipeline between the high-pressure hydrogen source (1) and the double ejector (2); a temperature sensor T3, a pressure sensor P3 and a hydrogen humidity sensor H1 are provided on the connecting pipeline between the hydrogen humidifier (4) and the simulated fuel cell (5); a temperature sensor T2 and a pressure sensor P2 are provided on the connecting pipeline between the simulated fuel cell (5) and the water separator (7); a hydrogen circulation flowmeter (8) and a flow resistance regulating valve (9) are provided on the connecting pipeline between the water separator (7) and the double ejector (2); and a temperature sensor T1 and a pressure sensor P1 are also provided; and a simulated hydrogen consumption valve (6) is provided on the output pipeline between the simulated fuel cell (5) and the atmosphere end; Based on the data information collected by the pressure sensor P1, the pressure sensor P2, the pressure sensor P3 and the hydrogen consumption flow meter (10), the pressure before and after the fuel cell stack and the hydrogen consumption information are determined by adjusting the simulated stack (5), the simulated hydrogen consumption valve (6) and the flow resistance regulating valve (10); Based on the data information detected by the temperature sensor T1, the temperature sensor T2, the temperature sensor T3 and the hydrogen humidity sensor H1, the hydrogen heater (3) and the hydrogen humidifier (4) are controlled to adjust the boundary range value of the test system.

2. A fuel cell variable injection flow offline model control device according to claim 1, characterized in that include: The double ejector (2) comprises a hydrogen inlet, a stack inlet, a hydrogen return inlet, a proportional valve 1 and a proportional valve 2, wherein the output end of a hydrogen consumption flow meter (10) is connected to the hydrogen inlet, the stack inlet is connected to the input end of a hydrogen heater (3), and the hydrogen return inlet is connected to the output end of a flow resistance regulating valve (9), wherein fresh hydrogen enters the double ejector (2) from the hydrogen inlet, mixes with mixed circulating hydrogen entering from the hydrogen return inlet, and enters the fuel cell stack from the stack inlet, wherein hydrogen output from the fuel cell stack enters the hydrogen return inlet; when high-pressure hydrogen enters the double ejector (2) and sequentially passes through the proportional valve 1 and the proportional valve 2 and the hydrogen supply channel where they are located, the proportional valve 1 is used for steady-state control and the proportional valve 2 is used for dynamic adjustment with the hydrogen inlet pressure as the target, a double ejector flow calculation model is generated by data fitting, the duty cycle of the proportional valve 1 is obtained by the model, and the fuel cell system dynamically adjusts the duty cycle of the proportional valve 2 based on the current hydrogen inlet pressure demand.

3. A fuel cell variable injection flow offline model control device according to claim 2, characterized in that include: According to the hydrogen operating conditions of the fuel cell under different working conditions, the offline calibration model is output according to the duty cycle of proportional valve 1 and proportional valve 2, the current hydrogen inlet pressure and temperature information, and the actual value of the current dual injection flow rate is output, compared with the corrected injection flow rate, and the deviation is summed and output as a correction value, ultimately achieving dynamic closed-loop control.

4. A fuel cell variable injection flow rate off-line model control device according to claim 3, characterized in that: The simulated hydrogen consumption valve (6) monitors the pressure difference between the pressure sensor P3 and the pressure sensor P2, and the output parameter of the hydrogen consumption flowmeter (10), so as to simulate the hydrogen consumption of the fuel cell under different working conditions. The flow resistance regulating valve (9) realizes the actual flow resistance of the simulated pipeline by controlling the target feedback value of the pressure sensor P1.

5. A fuel cell variable injection flow rate off-line model control device according to claim 1, characterized in that: The water separator (7) integrates a water and hydrogen discharge electromagnetic valve therein, separates liquid water from the entire device through a centrifugal impact water separation structure, and controls the switching frequency of the electromagnetic valve to simulate the actual operating state of the fuel cell system while protecting the working process of the hydrogen circulation flow meter (8).

6. A fuel cell variable injection flow rate off-line model control device according to claim 2, characterized in that: When the deviation of the blind-end cell of the stack is greater than the set threshold, the difference between the deviation value and the set threshold is converted and output as a corresponding correction value. The sum of the correction value and the target injection flow rate is used as part of the input value of the dual injection flow calculation model at this stage.

7. A fuel cell variable injection flow rate off-line model control device according to claim 6, characterized in that: The deviation between the corrected ejection flow rate and the actual flow rate is compared, and the difference obtained and the corrected ejection flow rate are summed as the final input value of the double ejection flow calculation model.

8. A fuel cell variable injection flow rate off-line model control device according to claims 1 to 7, characterized in that: The control method of the device is as follows: S1, the fuel cell system starts and enters the operating state; S2. Calculate the target current based on the required power and the current stack voltage, and check the single-cell deviation value at the blind end of the stack at the same time; S3, according to the target current, the target induced flow rate value is obtained by looking up the table, and the flow rate correction value is obtained according to the monomer deviation value. The two are summed to obtain the corrected induced flow rate as the calculation input value; S4, after summing up the secondary correction of the corrected ejection flow and the comparison flow deviation, input the final value into the double ejection flow calculation model, and output a duty cycle of the proportional valve; S5. According to the control target of hydrogen inlet pressure under the current working condition, dynamically adjust the proportional valve 2 and output the duty ratio of the proportional valve 2; S6. Use the offline calibration model to obtain the input value of the duty cycle of proportional valve 1 and proportional valve 2. At the same time, according to the current hydrogen inlet pressure and temperature information, output the current actual value of the dual injection flow rate, and return the data at the same time. Compare the corrected injection flow rate in S3 for secondary correction, so that the duty cycle of proportional valve 1 and proportional valve 2 can be dynamically adjusted in a closed loop.

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