Heating control device and method for proton exchange membrane fuel cell ejector

Abstract

This invention relates to a heating control device and method for a proton exchange membrane fuel cell ejector, belonging to the field of fuel cell control technology. The device uses a high-pressure hydrogen source to generate high-pressure hydrogen gas that enters the ejector. The ejector heating device heats the ejector valve body. The high-pressure hydrogen gas enters the fuel cell stack via the ejector, and the mixed gas discharged from the stack enters a hydrogen circulation device. Finally, residual hydrogen gas flows back to the ejector. The controller is electrically connected to both the temperature sensor in the ejector heating device and the flow sensor in the ejector. Based on the flow rate detection value, the operating status of the ejector is determined. Heating is initiated when the real-time flow rate is abnormal and the temperature is below the set value. An improved PID algorithm is used to output the optimal heating power. This invention solves the problems of uncontrollable valve opening and sealing ring failure in extreme low-temperature environments of -43°C and below, achieving precise temperature control of the ejector and reliable startup of the fuel cell system.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell control technology, specifically relating to a heating control device and method for a proton exchange membrane fuel cell ejector. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) are an important direction in the development of new energy sources. They use hydrogen as fuel and convert chemical energy directly into electrical energy through an electrochemical reaction, with water as the only byproduct. They have significant advantages such as high energy conversion efficiency, high energy density, and environmental friendliness, and have been widely used in civilian vehicles, military equipment, and portable power supplies.

[0003] The ejector is a core component of the hydrogen supply system on the anode side of a fuel cell. It operates based on Bernoulli's principle: high-pressure hydrogen is jetted through a nozzle to create a low-pressure zone in the ejector chamber, which entrains the unreacted hydrogen, water vapor, and nitrogen mixture returning from the anode outlet of the fuel cell stack. This mixture is then mixed with fresh hydrogen and reintroduced into the stack. This process not only achieves hydrogen recycling and improves hydrogen utilization efficiency, but the returned mixture also humidifies the hydrogen at the stack inlet, helping to maintain the water content of the proton exchange membrane. Since the ejector is powered by the high-pressure hydrogen source itself, it requires no additional electrical energy, thus contributing to improved overall efficiency of the fuel cell stack system.

[0004] However, the factory-specified operating temperature of ejector valves (especially proportional valves) in existing technologies is typically above -40°C. In extreme low-temperature conditions below -35°C, ejector valves exhibit inconsistent operation and uncontrollable valve opening, resulting in hydrogen fuel flow rates failing to match the power requirements of the fuel cell stack, and the fuel cell system malfunctioning. More seriously, existing ejectors cannot meet the operating requirements at extreme temperatures of -43°C and below, severely restricting the application of fuel cells in cold regions and high-altitude low-temperature environments.

[0005] Existing cryogenic start-up technologies mostly focus on heating the fuel cell stack itself (such as using heated coolant, additional DC power, air heating wire, etc.) or auxiliary heating solutions for icing at the ejector inlet. These solutions have the following shortcomings: First, using coolant circulation to heat the ejector is an indirect heating method, with high thermal inertia and poor real-time performance, making it unable to quickly respond to the ejector valve's temperature-sensitive requirements; second, it does not consider the hardening, embrittlement, and decreased elasticity of the ejector valve seals at extreme low temperatures, and seal failure will lead to the valve's inability to accurately regulate hydrogen flow; third, it lacks a refined control strategy for heating power, and does not comprehensively consider the coupled effects of multiple factors such as valve self-heating, cold hydrogen heat absorption, and waste heat from circulating hydrogen, resulting in high energy consumption and low temperature control accuracy. Summary of the Invention

[0006] To address the problems in the prior art, this invention proposes a heating control device and method for the ejector of a proton exchange membrane fuel cell, which solves the technical problems in the prior art where the valve opening of the ejector is uncontrollable and the sealing ring fails, causing the fuel cell system to malfunction under low temperature conditions, and meets the working requirements of fuel cells in extreme low temperature environments of -43℃ and below.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a heating control device for a proton exchange membrane fuel cell ejector, including a high-pressure hydrogen source, wherein the high-pressure hydrogen source supplies hydrogen to the ejector; The ejector includes a switching valve, a first proportional valve, a second proportional valve, a flow sensor, and an ejector body; the valve bodies of the three valves are integrated into the ejector body and are all electrically connected to the controller. The switching valve controls the opening and closing of the hydrogen path, and the first proportional valve and the second proportional valve are both used to regulate the hydrogen flow rate. The flow sensor is located between the first proportional valve and the second proportional valve and the fuel cell stack. Both valves are electrically connected to the controller and are used to detect the hydrogen flow rate before entering the fuel cell stack in real time. It also includes an ejector heating device, which includes an explosion-proof flame-retardant heat-insulating shell, an electric heating wire, a first temperature sensor, a second temperature sensor, and an electromechanical switch; The explosion-proof, flame-retardant, and heat-insulating outer shell is fitted around the outer wall of the ejector body and is slightly larger than the ejector body structure to reduce heat loss. An electric heating wire is installed in the gap, and the electric heating wire is evenly wrapped around the outer wall of the ejector body. Heat is conducted to each valve sealing ring through the metal wall surface. The first temperature sensor is located in the middle of the first proportional valve body, and the second temperature sensor is located in the middle of the second proportional valve body. Both temperature sensors are electrically connected to the controller and are used to monitor the temperature of the two proportional valves in real time. The electromechanical switch is located at the bottom of the ejector and is electrically connected to the controller to adjust the opening degree to prevent overheating. It also includes a hydrogen circulation device, which includes a gas-water separator, a drain valve, and a nitrogen discharge valve. The drain valve and the nitrogen discharge valve are located downstream of the gas-water separator and are both electrically connected to the controller.

[0008] Furthermore, the controller uses an improved PID algorithm to output an optimal power setpoint to adjust the electric heating wire. The formula for calculating the optimal power setpoint is: K is the control coefficient, the subscript p represents the proportional control coefficient (response speed), the subscript i represents the integral control coefficient (eliminating steady error), and the subscript d represents the derivative control coefficient (suppressing oscillation). To set the deviation between the current temperature and the set temperature, t represents the time variable; when When operating at full power, According to the formula above, when Stop working; Current traffic; This represents the maximum flow rate of the ejector. Represents heating power percentage; The positive impact of the valve's self-generated heat on the percentage of heating power; The negative impact of cold hydrogen entering the ejector on the percentage of heating power; The positive effect of hydrogen entering the ejector during thermal cycling on the percentage of heating power; The controller is based on the current minimum temperature of the two proportional valves. The interval in which it is located implements a segmented control strategy: when When the heating element is at full power, the electric heating wire operates at full power; when When, calculate and output according to the above formula; when At that time, the electric heating wire stops working.

[0009] Furthermore, the gas-water separator consists of a rotating device and a cooling baffle, used to separate the mixed gas containing unreacted hydrogen, nitrogen and liquid water discharged from the anode of the fuel cell stack; the liquid water is separated by the rotating device under centrifugal force and is captured by impacting the cooling baffle; when the liquid water accumulates to a first threshold, the drain valve opens; when the nitrogen concentration in the mixed gas reaches a second threshold, the nitrogen discharge valve opens; the separated hydrogen is returned to the ejector for recycling.

[0010] Furthermore, the electromechanical switch is a bimetallic strip temperature control switch or a shape memory alloy driven switch. When the temperature of the ejector body exceeds the safety threshold, it automatically cuts off or reduces the power supply of the electric heating wire. The electromechanical switch is electrically connected to the controller via a hard wire.

[0011] Furthermore, the explosion-proof, flame-retardant, and heat-insulating outer shell has a multi-layer composite structure, consisting of a high-temperature resistant ceramic fiber layer, an aerogel insulation layer, and a stainless steel protective layer from the inside out.

[0012] Furthermore, the winding density of the electric heating wire at the valve sealing ring connection of the switching valve, the first proportional valve, and the second proportional valve is 1.5-3 times that of the main body winding density.

[0013] Furthermore, the high-pressure hydrogen source is an on-board hydrogen storage cylinder group with an outlet pressure of 35-70 MPa, which provides 0.5-2.0 MPa of hydrogen to the ejector after pressure reduction.

[0014] Furthermore, the controller acquires analog signals from the first temperature sensor, the second temperature sensor, and the flow sensor through a built-in ADC module, and uses them for control calculations after digital filtering; the controller drives a solid-state relay through a built-in PWM timer output after optocoupler isolation, thereby adjusting the on / off duty cycle of the electric heating wire and realizing continuous adjustment of the heating power.

[0015] Furthermore, the switching valve, the first proportional valve, the second proportional valve, the drain valve, and the nitrogen discharge valve are all electrically connected to the controller via a CAN bus. The CAN bus has hardware-level error detection and priority arbitration mechanisms to ensure real-time and reliable transmission of control commands in extreme low-temperature environments.

[0016] Furthermore, the method using the heating control device for the proton exchange membrane fuel cell ejector according to claims 1-9 comprises the following steps: Step 1: The system is powered on and initialized. The controller acquires the real-time temperature value from the first temperature sensor. Real-time temperature value of the second temperature sensor ,Pick and the real-time flow value of the flow sensor. ; Step 2: Controller Judgment Is it within the preset traffic threshold range? If the flow rate is within the preset threshold range, it is further determined whether it meets the current low-power operating requirements. If it meets the current low-power operating requirements, it is determined that the ejector is working normally and returns to step one. If it does not meet the current low-power operating requirements, it switches to PID control mode and proceeds to step three. If the flow rate is not within the preset threshold range, it is not necessary to switch to PID control mode and proceeds directly to step three. Step 3: The controller makes further judgments. Is it below the set temperature? If yes, start the electric heating wire to heat the ejector and proceed to step four; if no, report a valve mechanical malfunction. Step 4: Set a preset interval Then, obtain the real-time traffic value again. Then return to step two for judgment until the ejector returns to normal operation or reaches the maximum heating time limit.

[0017] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. This invention integrates three valves (on / off valve and dual proportional valve) into the ejector body, employs a synergistic design including an electric heating wire uniformly covering a metal shell, dense winding at the sealing ring, independent monitoring and minimum value taking by dual temperature sensors, independent protection of the flow sensor, multi-factor dynamic compensation using an improved PID algorithm, hardware-level over-temperature protection for the electromechanical switch, hydrogen circulation waste heat recovery, and a multi-layer composite insulation shell. This achieves rapid and accurate temperature control and reliable start-up of the ejector valves in extreme low-temperature environments of -43 ℃ and below, solves the problem of uncontrollable flow caused by low-temperature sealing ring failure, improves hydrogen utilization efficiency, reduces heating energy consumption, and ensures system safety.

[0018] 2. The present invention, through a specially designed ejector heating device, can rapidly increase the temperature of the ejector valve and sealing ring in extreme low temperature environments of -43 ℃ and below, restore the controllability of valve opening, meet the requirements of extreme temperature operation, and solve the problem of starting up in extreme low temperatures.

[0019] 3. The valve bodies of the switching valve, the first proportional valve, and the second proportional valve of the present invention are integrated into the ejector body. The electric heating wire is uniformly wrapped around the metal shell of the ejector body. The heat is conducted to the three valve bodies through the metal wall and the wire is densely wound at the connection of the three valve sealing rings to achieve targeted enhanced heating of all key sealing parts, effectively alleviating the problem of low-temperature hardening and embrittlement of the sealing rings. The three valves are integrated to enhance heating.

[0020] 4. This invention employs dual-valve independent temperature monitoring. Since the first proportional valve and the second proportional valve are physically separated and have independent thermal inertia, this invention sets temperature sensors on each of the two valves and takes the lower value as the control basis to ensure that heating is started when either valve has not reached the minimum operating temperature, preventing flow control failure due to insufficient temperature of a single valve and achieving reliable coverage of all operating conditions.

[0021] 5. The flow sensor of the present invention is independent of the heating area of ​​the electric heating wire, avoiding measurement temperature drift caused by external heating; a preheating section is set in the upstream pipeline to prevent condensate from freezing, ensuring the accuracy and reliability of flow detection.

[0022] 6. This invention achieves refined control through multi-factor coupling. The improved PID algorithm comprehensively considers multiple factors such as temperature deviation, real-time flow rate, valve self-heating, cold hydrogen heat absorption, and circulating hydrogen waste heat to achieve dynamic optimization of heating power, avoid overheating or underheating, and reduce energy consumption.

[0023] 7. This invention uses abnormal flow rate as the criterion for valve failure and the lowest temperature of the dual valves as the heating trigger condition, forming a closed-loop logic of "flow rate diagnosis → temperature judgment → heating control → flow rate re-inspection", which ensures accurate diagnosis and reliable control.

[0024] 8. The electromechanical switch of the present invention provides over-temperature protection independently of the controller, which can prevent the ejector from overheating even if the controller fails, thereby improving system safety.

[0025] 9. The hydrogen circulation device of the present invention effectively separates liquid water and nitrogen, improving hydrogen utilization efficiency. Simultaneously, the returned circulating hydrogen carries residual heat, providing auxiliary heating for the ejector (corresponding to the formula). (Item), further reducing heating energy consumption. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the heating control device for the proton exchange membrane fuel cell ejector according to the present invention; Figure 2 This is a partial cross-sectional view of the ejector heating device of the present invention; Figure 3 This is a flowchart of the heating control device for the proton exchange membrane fuel cell ejector according to the present invention.

[0027] Explanation of reference numerals in the attached figures: 1. High-pressure hydrogen source; 2. Ejector; 21. Switch valve; 22. First proportional valve; 23. Second proportional valve; 24. Flow sensor; 25. Ejector body; 3. Ejector heating device; 31. Explosion-proof flame-retardant heat-insulating shell; 32. Electric heating wire; 331. First temperature sensor; 332. Second temperature sensor; 34. Electromechanical switch; 6. Controller; 4. Fuel cell stack; 5. Hydrogen circulation device; 51. Gas-liquid separator; 52. Drain valve; 53. Nitrogen discharge valve. Detailed Implementation

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0029] In the description of this invention, it is important to understand that CAN stands for Controller Area Network, a serial communication protocol standard initially developed by Bosch in Germany for automotive applications in 1986, and has now become one of the most widely used fieldbuses in the industrial field. ADC stands for Analog-to-Digital Converter, an electronic device that converts continuous analog signals into discrete digital signals, serving as a crucial interface connecting the physical world (analog signals) and digital systems (processors). PWM stands for Pulse Width Modulation Timer, a dedicated hardware module in microcontrollers used to generate precise pulse width modulation signals. The Ziegler-Nichols tuning method, or ZN method for short, is a classic PID controller parameter engineering tuning method proposed by John Ziegler and Nathaniel Nichols in 1942, used to quickly determine PID parameters based on the dynamic characteristics of the controlled object. The technical terms "inner," "outer," "front," "outer wall," "middle," "bottom," and "downstream," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention. The terms "first," "second," and similar words used in the embodiments of the present invention do not indicate any order, quantity, or importance, but are only used to distinguish different components.

[0030] Words such as "include" or "contain" mean that the element preceding the word covers the elements listed after the word and their equivalents, without excluding other elements. Words such as "connect," "connect," or "fix" are not limited to a single connection or fixing method, but can include multiple connection or fixing methods, such as screw fastening, threaded connection, welding, etc.

[0031] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. A heating control device and method for a proton exchange membrane fuel cell ejector includes: a high-pressure hydrogen source 1, an ejector 2, a switching valve 21, a first proportional valve 22, a second proportional valve 23, a flow sensor 24, an ejector body 25, an ejector heating device 3, an explosion-proof and flame-retardant heat-insulating shell 31, an electric heating wire 32, a first temperature sensor 331, a second temperature sensor 332, an electromechanical switch 34, a controller 6, a fuel cell stack 4, a hydrogen circulation device 5, a gas-liquid separator 51, a drain valve 52, and a nitrogen discharge valve 53.

[0032] High-pressure hydrogen source 1 generates high-pressure hydrogen that enters ejector 2, and then enters fuel cell stack 4. Fuel cell stack 4 generates mixed gas that enters hydrogen circulation device 5, and finally the residual hydrogen is recycled back to ejector 2. The ejector heating device 3 heats the ejector 2 to ensure that the ejector 2 works normally.

[0033] Preferably, the controller 6 uses an improved PID algorithm to output the optimal power setting value to adjust the electric heating wire, enabling rapid start-up at extreme low temperatures, avoiding PID integral saturation and slow response at low temperatures, quickly restoring the elasticity of the sealing ring, and providing refined energy consumption management to avoid oscillations of "overheating at full power" or "insufficient power". Compared with simple PID, energy consumption is reduced by about 10-15%.

[0034] Preferably, the gas-liquid separator 51 consists of a rotating device and a cooling baffle, used to separate the mixed gas containing unreacted hydrogen, nitrogen and liquid water discharged from the anode of the fuel cell stack 4; the liquid water is separated by the rotating device under centrifugal force and is captured by impacting the cooling baffle; when the liquid water accumulates to the first threshold, the drain valve 52 opens; when the nitrogen concentration in the mixed gas reaches the second threshold, the nitrogen discharge valve 53 opens; the separated hydrogen is returned to the ejector for recycling. The gas-liquid separator 51 adopts a combination structure of centrifugal rotating device and cooling baffle to achieve two-stage high-efficiency separation of liquid water and hydrogen, with a separation efficiency of over 95%. With automatic drainage based on liquid level threshold and automatic nitrogen removal based on nitrogen concentration threshold, it ensures that the hydrogen water content and nitrogen concentration returning to ejector 2 are below 5%, effectively preventing performance degradation caused by water flooding, low-temperature freezing, and nitrogen accumulation in fuel cell stack 4. At the same time, it utilizes the waste heat of circulating hydrogen to reduce heating energy consumption, thereby increasing the hydrogen utilization rate to over 90%.

[0035] Preferably, the electromechanical switch 34 is a bimetallic strip temperature control switch or a shape memory alloy driven switch, which automatically cuts off or reduces the power supply of the electric heating wire when the temperature of the ejector body 25 exceeds the safety threshold. The electromechanical switch 34 is electrically connected to the controller 6 through a hard wire. The electromechanical switch 34 adopts a bimetallic strip temperature control switch or a shape memory alloy driven switch, which is connected in series in the power supply circuit of the electric heating wire. When the temperature of the ejector body 25 exceeds the safety threshold (such as 85 ℃), the power supply is automatically cut off, forming a hardware-level over-temperature protection independent of the controller. At the same time, the electromechanical switch 34 feeds back the status signal to the GPIO port of the controller 6 through hard wiring. After the controller 6 detects the jump signal, it records the fault event and stops the PWM timer output, forming a dual safety linkage mechanism of "hardware cut-off + software stop", which effectively prevents thermal runaway caused by controller failure and improves the system safety integrity level.

[0036] Preferably, the explosion-proof, flame-retardant, and heat-insulating shell 31 has a multi-layer composite structure, consisting of a high-temperature resistant ceramic fiber layer, an aerogel insulation layer, and a stainless steel protective layer from the inside out. More preferably, the explosion-proof, flame-retardant, and heat-insulating outer shell 31 has a multi-layer composite structure. The inner layer is a 3 mm ceramic fiber felt with a temperature resistance of 1200℃ and a thermal conductivity of 0.03 W / (m·K). The middle layer is a 5 mm aerogel felt with a thermal conductivity of only 0.015 W / (m·K). The outer layer is a 1 mm 304 stainless steel plate that provides mechanical protection and sealing. The three layers work together with a 5 mm gap static air layer to form a multi-level thermal resistance series, reducing heat loss to less than 5% of the heating power. At the same time, it achieves lightweight (total weight of about 0.3 kg), flame retardancy, explosion protection, and corrosion resistance, ensuring that the outer shell does not burn or melt under extreme working conditions, thereby improving system safety and energy efficiency.

[0037] Preferably, the electric heating wire 32 is densely wound at the valve sealing ring connection of the switching valve 21, the first proportional valve 22, and the second proportional valve 23, with the winding density increased to 1.5-3 times that of the main body (e.g., the pitch is increased from 10 mm to 4 mm), thereby increasing the power density at the sealing ring by 2-3 times. This targeted enhanced heating quickly crosses the glass transition temperature range of the sealing ring material (the time from -43 ℃ to -35 ℃ is shortened from ~90 s to ~35 s), eliminating the local low-temperature dead zone where "the valve body is hot but the sealing ring is still cold", ensuring that the elasticity of the three valve sealing rings recovers synchronously, increasing the success rate of opening under all working conditions to over 95%, while reducing the accumulation of thermal stress in the embrittlement zone of the sealing ring and extending the low-temperature cycle life by 2-3 times.

[0038] Preferably, the high-pressure hydrogen source 1 uses an on-board 35 MPa or 70 MPa hydrogen storage cylinder group, which is reduced to 0.5-2.0 MPa by a first-stage pressure reducing valve before supplying the ejector 2; high-pressure hydrogen storage increases the mass / volume hydrogen storage density by more than 40%, meeting the requirements for long-range vehicle operation; after pressure reduction, the pressure matches the optimal operating range of the ejector's Bernoulli effect (ejection ratio 2~4, hydrogen utilization rate >90%), while simultaneously reducing most of the system's pipelines to a medium-low pressure safety level; the Joule-Thomson temperature drop effect during the pressure reduction process is incorporated into the PID algorithm. Dynamic compensation ensures that the heating power is precisely matched to the heat absorption requirements of cold hydrogen at extreme low temperatures.

[0039] Preferably, the controller 6 acquires analog signals from the first temperature sensor 331, the second temperature sensor 332, and the flow sensor 24 through a built-in ADC module, and uses them for control calculations after digital filtering; the controller 6 drives a solid-state relay through a built-in PWM timer output after optocoupler isolation, and adjusts the duty cycle of the electric heating wire to achieve continuous adjustment of the heating power. More preferably, controller 6 uses an STM32F407 microcontroller as its core, with a built-in 12-bit ADC module that acquires analog signals from temperature and flow sensors at a rate of 2.4 MSPS. After median filtering and moving average filtering, the signal-to-noise ratio is improved by more than 20 dB, ensuring the input accuracy of control operations. It also has a built-in 16-bit PWM timer that outputs the duty cycle signal with hardware-level timing. This signal is then driven by a solid-state relay via optocoupler isolation (with withstand voltage >2500 V), enabling continuous adjustment of the on / off duty cycle of the heating wire. The power resolution is 0.2 W, and the frequency is stable without jitter. This closed-loop control system, which integrates "ADC acquisition → digital filtering → PID calculation → PWM output → optocoupler isolation → solid-state relay driving," has a response time of <5 ms and a temperature control accuracy of ±0.3 ℃. At the same time, optocoupler isolation cuts off the high-voltage fault propagation path, and the solid-state relay has a contactless lifespan of over 10 million cycles, significantly improving system reliability and energy efficiency.

[0040] Preferably, the switching valve 21, the first proportional valve 22, the second proportional valve 23, the drain valve 52, and the nitrogen discharge valve 53 are all electrically connected to the controller 6 via a CAN bus. The CAN bus has hardware-level error detection and priority arbitration mechanisms to ensure real-time and reliable transmission of control commands in extreme low-temperature environments. The CAN bus uses differential signal transmission and features hardware-level CRC error detection, ACK response confirmation, and a non-destructive priority arbitration mechanism. In extreme low-temperature environments of -43 ℃, compared to traditional point-to-point wiring harnesses, the CAN bus reduces the number of wiring harnesses from 10 to 2, reducing weight by approximately 0.5 kg. At the same time, it ensures that emergency cut-off commands (such as over-temperature protection) preempt bus transmission within <1ms through identifier priority, while non-emergency commands are automatically queued to prevent packet loss. The status of each valve is transmitted back to the controller 6 in real time, forming a closed-loop diagnosis of 'command issuance - execution verification - status feedback', improving system reliability and maintainability.

[0041] The heating control device and method for a proton exchange membrane fuel cell ejector are detailed below: 1. Device Structure Configuration The proton exchange membrane fuel cell ejector heating control device of this embodiment includes a high-pressure hydrogen source 1, an ejector 2, an ejector heating device 3, a fuel cell stack 4, a hydrogen circulation device 5, and a controller 6.

[0042] 1) Composition of High-Pressure Hydrogen Source 1: High-pressure hydrogen source 1 uses an on-board 35 MPa hydrogen storage cylinder group, electrically connected to controller 6. During system startup, controller 6 first checks if the ejector 2 temperature meets the standard, then sequentially opens high-pressure hydrogen source 1 and switch valve 21 to prevent damage to the sealing ring caused by high-pressure hydrogen impact at low temperatures. High-pressure hydrogen source 1 provides high-pressure hydrogen to the system, reducing the pressure to the required inlet pressure range of 0.5-2.0 MPa for ejector 2 via a primary pressure reducing valve. High-pressure hydrogen source 1 and ejector 2 are connected via a high-pressure pipeline, on which a manual shut-off valve, filter, and safety relief valve are sequentially installed along the hydrogen flow direction. Under low-temperature startup conditions, the cold hydrogen output from high-pressure hydrogen source 1 has the same temperature as the ambient temperature (-43 ℃). This cold hydrogen, upon entering ejector 2, produces a significant endothermic effect, which has a negative impact on the improved PID algorithm. China will provide compensation.

[0043] 2) Composition of Ejector 2: Ejector 2 includes a switching valve 21, a first proportional valve 22, a second proportional valve 23, a flow sensor 24, and an ejector body 25. The valve bodies of the switching valve 21, the first proportional valve 22, and the second proportional valve 23 are integrated within the ejector body 25. The switching valve 21 is a solenoid shut-off valve with a coil resistance of approximately 15 Ω and a rated voltage of 24 V. During system startup, the controller 6 first detects... The system checks whether the requirements are met before issuing an opening command to prevent forced opening at low temperatures from damaging the sealing rings and to control the opening and closing of the main hydrogen pipeline. The first proportional valve 22 has a flow regulation range of 0-30% of rated flow, used for low-power applications (0-30% of rated power), while the second proportional valve 23 has a flow regulation range of 20-100% of rated flow, used for high-power applications (30-100% of rated power). The two proportional valves are physically separated, approximately 150 mm apart, and each has independent thermal inertia. All three valves receive commands from controller 6 via a CAN bus for switching. The flow sensor 24 is installed between the first proportional valve 22 and the second proportional valve 23 and the fuel cell stack 4, independent of the heating area of ​​the electric heating wire 32, with a range of 0-500 NL / min and an accuracy of ±1% FS, and is used to detect the flow rate of hydrogen before entering the fuel cell stack 4.

[0044] 3) Composition of ejector heating device 3: ejector heating device 3 includes explosion-proof flame-retardant heat-insulating shell 31, electric heating wire 32, temperature sensor 33 and electromechanical switch 34; The explosion-proof, flame-retardant, and heat-insulating outer shell 31 is made of a high-temperature resistant, non-flammable material with low thermal conductivity, and its size is slightly larger than that of the hydrogen ejector body 25. The explosion-proof, flame-retardant, and heat-insulating outer shell 31 has a three-layer structure: the inner layer is a 3 mm thick ceramic fiber felt (temperature resistance 1200℃, thermal conductivity 0.03 W / (m·K)), the middle layer is a 5 mm thick aerogel felt (thermal conductivity 0.015 W / (m·K)), and the outer layer is a 1 mm thick 304 stainless steel plate. A 5 mm gap is left between the explosion-proof, flame-retardant, and heat-insulating outer shell 31 and the outer wall of the ejector body 25, and the electric heating wire 32 is placed in this gap. The heating wire 32 is a nickel-chromium alloy wire (Cr20Ni80), with a diameter of 0.5 mm and a resistivity of approximately 1.09 Ω·mm. 2 The total power is designed to be 200 W, powered by a 24 V system power supply (rated current approximately 8.3 A). The heating wire 32 is evenly wrapped around the metal shell of the ejector body 25. The metal shell of the ejector body 25 integrates the valve bodies of the switching valve 21, the first proportional valve 22, and the second proportional valve 23. The heat from the heating wire 32 is conducted to the valve sealing rings through the metal wall. The main body has a winding pitch of 10 mm, while at the connection points of the three valve sealing rings (each approximately 30 mm in length), the winding pitch is increased to 4 mm (density 2.5 times that of the main body) to enhance independent heating of the three valve sealing rings. The flow sensor 24 is independent of the heating area of ​​the electric heating wire 32. The flow sensor 24 is a thermal mass flow meter, and the upstream pipeline is naturally preheated through heat conduction from the ejector body 25 to prevent condensate from freezing and clogging, thus ensuring the accuracy and reliability of flow detection. The temperature sensors include a first temperature sensor 331 and a second temperature sensor 332, which are located at the valve of the hydrogen ejector 2 to monitor the operating temperature of the hydrogen ejector 2 in real time. Both the first temperature sensor 331 and the second temperature sensor 332 are PT100 platinum resistance thermometers. The first temperature sensor 331 is located in the middle of the valve body of the first proportional valve 22, and the second temperature sensor 332 is located in the middle of the valve body of the second proportional valve 23, for real-time monitoring of the valve temperature. Since the two proportional valves are physically separate and have independent thermal inertia, they need to be monitored separately to ensure temperature controllability under all operating conditions. The controller 6 collects the temperature values ​​of the two valves and selects the lower value. As a control basis, ensure that heating is activated when any valve has not reached the minimum operating temperature, to prevent flow control failure due to insufficient temperature of a single valve; The electromechanical switch 34 is a KSD301 bimetallic strip temperature control switch with an operating temperature set at 85℃ and a reset temperature of 60℃. It is connected in series in the power supply circuit of the electric heating wire 32 and installed on the metal base at the bottom of the ejector 2.

[0045] 4) Composition of the hydrogen circulation device 5: The hydrogen circulation device 5 includes a gas-liquid separator 51, a drain valve 52, and a nitrogen discharge valve 53. The gas-liquid separator 51 consists of a rotating device and a cooling baffle. The gas-liquid separator 51 adopts a centrifugal structure, with the rotating device rotating at 3000 rpm, and the cooling baffle is made of stainless steel corrugated plate. The gas-liquid separator 51 is a passively operating mechanical structure. The rotating device is driven to rotate by the mixed gas flow discharged from the anode of the fuel cell stack 4, requiring no external power or control signal, and continuously performs gas-liquid separation. The drain valve 52 is a solenoid valve, electrically connected to the controller 6, and its opening is controlled by the controller 6 based on the liquid level sensor signal; the nitrogen discharge valve 53 is a proportional valve, electrically connected to the controller 6, and its opening degree is controlled by the controller 6 based on the nitrogen concentration sensor signal. The mixed gas discharged from the anode of fuel cell stack 4 contains unreacted hydrogen, nitrogen diffused from the cathode to the anode, and liquid water. The liquid water is separated from the mixed gas by centrifugal force through a rotating device, and then continues to impact the cooling baffle due to inertia, where it is captured. When the liquid level sensor detects that the liquid water has accumulated to a threshold of 50 mL, the drain valve 52 opens, and the liquid water enters the atmosphere via the tailpipe. When the nitrogen concentration sensor detects that the nitrogen concentration in the mixed gas exceeds 5% (a preset concentration), the nitrogen vent valve 53 opens to ensure the hydrogen concentration returning to ejector 2, and the nitrogen enters the atmosphere via the tailpipe. Finally, after the liquid water and nitrogen are separated from the mixed gas, the residual hydrogen is recycled back to ejector 2, which improves the hydrogen utilization efficiency.

[0046] 5) Structure of controller 6: Controller 6 is a fuel cell system controller (FCU), which is installed in the system control box and is electrically connected to flow sensor 24, first temperature sensor 331, second temperature sensor 332, electromechanical switch 34, switching valve 21, first proportional valve 22, second proportional valve 23, drain valve 52 and nitrogen discharge valve 53 through the vehicle wiring harness. The controller 6 is based on an STM32F407 microcontroller and integrates a multi-channel 12-bit ADC module, a PWM timer, and a CAN bus communication interface. The ADC module collects voltage signals from the first temperature sensor 331 and the second temperature sensor 332 to obtain the real-time temperature of the two valves, using the lower value to determine whether heating needs to be activated. The ADC module also collects the voltage signal from the flow sensor 24 after signal conditioning to obtain the real-time hydrogen flow rate before entering the fuel cell stack 4, thus determining whether the ejector 2 valve is functioning correctly. The PWM timer output, after optocoupler isolation, drives a solid-state relay to adjust the duty cycle of the heating wire 32, achieving continuous adjustment of the heating power. The CAN bus interface connects to the vehicle's CAN bus network, sending signals to the first proportional valve 22 and the second proportional valve 332. For example, valve 23 sends an opening command to adjust the hydrogen flow rate, receives a power demand signal from the vehicle controller to coordinate the heating control and the operating status of the fuel cell stack 4, and feeds back the temperature and flow rate of ejector 2 and the operating status of ejector heating device 3 to the vehicle controller; the switching status of electromechanical switch 34 is input to the GPIO port of controller 6 via hardwire. When electromechanical switch 34 cuts off the power supply circuit of electric heating wire 32 due to overheating, controller 6 detects the state transition signal, records the overheating protection event, and stops outputting PWM timer heating commands, forming a dual safety mechanism of hardware-level overheat protection and software control linkage.

[0047] 2. A method for heating control of a proton exchange membrane fuel cell ejector: 1) Control parameter calibration method Control parameters in the improved PID algorithm , , and compensation coefficient , , The following offline experimental calibration method was used to determine: a. PID basic parameter calibration: At room temperature (25 ℃), ejector 2 is placed in a constant temperature environment, hydrogen circulation device 5 is disconnected, and a step power (from 0 W to 100 W) is applied to electric heating wire 32. The temperature response curves at the two valves are recorded. Based on the delay time L and time constant T of the response curve, the initial PID parameters are calculated using the Ziegler-Nichols tuning method. The final values ​​are then determined through multiple fine-tuning experiments under low temperature conditions (-40 ℃, -30 ℃, -20 ℃). b. Negative influence coefficient of cold hydrogen Calibration: Under steady-state heating conditions (maintaining) Hydrogen gas at different temperatures (-40℃, -30℃, -20℃) and flow rates (10, 50, 100 NL / min) was introduced, and the increase in heating power required to maintain the temperature was recorded. The results were then fitted to obtain... The relationship between hydrogen inlet temperature and flow rate; c. Positive influence coefficient of valve self-generated heat Calibration: Under the same steady-state conditions, adjust the first proportional valve 22 and the second proportional valve 23 to different opening degrees, record the reduction in heating power required to maintain the temperature, and establish an opening degree-self-generated heat calibration curve; d. Positive influence coefficient of waste heat from circulating hydrogen Calibration: Connect the hydrogen circulation device 5, adjust the output power of the fuel cell stack 4 to change the temperature of the circulating hydrogen, and record the reduction in heating power required to maintain the temperature of the ejector 2.

[0048] 2) Low-temperature start-up control process Step 1: Set the ambient temperature to -43℃, and the fuel cell system receives the start command. The system is powered on and initialized. Controller 6 collects the readings from the first temperature sensor 331. The readings of the second temperature sensor 332 and the flow sensor 24 are collected. ,Pick Real-time flow rate values ​​are obtained by collecting readings from flow sensor 24. At this time, the three valves are closed due to the hardening of the low-temperature sealing rings, and no hydrogen flows into the fuel cell stack 4; Step 2: Controller 6 makes a judgment Not within the preset threshold range Internal (Settings) , The threshold is determined based on the minimum hydrogen demand of fuel cell stack 4 under idling conditions and 96% of the full scale of flow sensor 24, indicating that ejector valve 2 has failed. Step 3: (This setting is determined based on the low-temperature embrittlement transition temperature of the valve sealing ring material, nitrile rubber, and the valve's minimum operating temperature.) Controller 6 activates the electric heating wire 32 at full power (200 W). Due to... Controller 6 directly enters full-power heating mode and does not enable PID calculation; Step 4: Interval Then, controller 6 collects real-time flow values ​​again. During this 60-second full-power heating period, the temperature of the ejector body 25 rose from -43 ℃ to -38 ℃, with an actual effective temperature rise of The temperature rise was verified by estimating the equivalent heat capacity and heating power of ejector 2: the ejector body 25 (stainless steel) weighs approximately 2 kg, with an equivalent specific heat capacity of approximately 500 J / (kg·K), and an equivalent heat capacity of... Theoretical temperature rise After considering the heat dissipation loss of the explosion-proof, flame-retardant, and thermally insulating shell 31, the heat absorption of cold hydrogen, and the heat conduction loss of the metal bracket, the actual effective temperature rise is... Approximately 5°C, consistent with the actual temperature rise to -38°C; At this point, the sealing ring partially regains its elasticity, allowing the valve to open slightly. The measurement... Although this flow rate is higher than the minimum idle speed threshold (A value below this indicates complete valve failure, meaning the valve is still closed or stuck), but below the target flow rate for the current low-temperature start-up self-test condition. (This target value is determined based on a comprehensive calibration of 20% of the rated power of fuel cell stack 4 under low load conditions and a hydrogen stoichiometry ratio of 1.5, corresponding to the maximum flow rate of ejector 2.) (20% of the original value). Therefore, controller 6 determines that ejector 2 is in a partially failed state and needs to continue heating until it is fully restored. Controller 6 switches to PID control mode and calculates the heating power percentage according to the improved PID formula. The heating device is adjusted using a PID algorithm to output the optimal power setpoint. The formula for calculating the optimal power setpoint is as follows: K is the control coefficient, the subscript p represents the proportional control coefficient (response speed), the subscript i represents the integral control coefficient (eliminating steady error), and the subscript d represents the derivative control coefficient (suppressing oscillation). To set the deviation between the current temperature and the set temperature, t represents the time variable; when When operating at full power, According to the formula above, when Stop working; Current traffic; This represents the maximum flow rate of ejector 2; Represents heating power percentage; The positive impact of the valve's self-generated heat on the percentage of heating power; The negative impact of cold hydrogen entering ejector 2 on the percentage of heating power; The positive effect of hydrogen entering ejector 2 during thermal cycling on the percentage of heating power; The basis for setting each parameter and the calculation process are as follows: Step 4.1 Deviation Item set up , Deviation items: Step 4.2 Proportional Term set up (Obtained through step response method experimental calibration) Proportional term: Step 4.3 Integration Term During the first 60 seconds of full-power heating, the deviation... From initial value It decays exponentially to its current value. , Its time integral is estimated using the trapezoidal method. set up (Integral time constant) Therefore ) Integral term: Step 4.4 Differential Term The current temperature rises by 5°C in 60 seconds, therefore the current temperature rise rate is... Therefore (The negative sign indicates that the deviation is decreasing) Differential coefficients , ,in ( Taking 1 / 4 of the ejector's thermal inertia time constant, which is approximately 1 s as measured by step response experiments (and conservatively considering the increased thermal resistance of the sealing ring under low-temperature conditions), therefore... This is used to suppress temperature overshoot; Differential term: Step 4.5 Flow Correction Coefficient Current traffic Ejector 2 maximum flow rate (With the same range as the flow sensor), therefore ; Step 4.6 Compensation Item Calibration Value At a small opening, the equivalent power from throttling and self-generated heat by the electromagnetic coil is approximately 10 W, accounting for 5% of the total power of the electric heating wire (200 W). The value is determined by the valve opening-power consumption calibration experiment; The equivalent power of the cold hydrogen gas absorbing heat is approximately 16 W, accounting for 8% of the total power of the electric heating wire (200 W). ; The equivalent power of the waste heat from the circulating hydrogen is approximately 4 W, as determined by the heat balance experiment of the hydrogen circulation device 5. Substituting into the formula, we get: = (6 + 33 - 0.042) × 0.03 - 5 + 8 - 2 = 38.958 × 0.03 + 1 =2.17% Because the calculated value is low and still in During the interval, controller 6 maintains a moderate heating power (controller 6 is set to a minimum output limit of 20% duty cycle, approximately 40 W) to prevent localized overheating of the surface of electric heating wire 32 in a low temperature and high humidity environment, while ensuring temperature response speed and continuing to heat up; In 60 seconds, , , All three valves are fully restored. (Meets the requirements of current low-power operation) Within the threshold range, ejector 2 is determined to be working normally, controller 6 stops heating, and the system enters normal operation mode.

[0049] 3) Over-temperature protection verification When controller 6 malfunctions and continues to output full power for heating, the temperature of ejector body 25 rises to 85 ℃. At this point, electromechanical switch 34 (bimetallic strip) activates, cutting off the power supply circuit to heating wire 32, and ejector 2 stops heating. When the temperature drops to 60 ℃, the switch resets. However, if controller 6 still malfunctions, it will heat up to 85 ℃ again to cut off the circuit, forming a cyclic protection system to ensure that ejector 2 will not overheat and be damaged.

[0050] The above description is merely a detailed account of one embodiment of the present invention, but it is only a preferred embodiment and should not be considered as limiting the scope of the invention. All equivalent variations and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A heating control device for a proton exchange membrane fuel cell ejector, characterized in that: A heating control device for a proton exchange membrane fuel cell ejector includes a high-pressure hydrogen source that supplies hydrogen to the ejector; The ejector includes a switching valve, a first proportional valve, a second proportional valve, a flow sensor, and an ejector body; the valve bodies of the three valves are integrated into the ejector body and are all electrically connected to the controller. The switching valve controls the opening and closing of the hydrogen path, and the first proportional valve and the second proportional valve are both used to regulate the hydrogen flow rate. The flow sensor is located between the first proportional valve and the second proportional valve and the fuel cell stack. Both valves are electrically connected to the controller and are used to detect the hydrogen flow rate before entering the fuel cell stack in real time. It also includes an ejector heating device, which includes an explosion-proof flame-retardant heat-insulating shell, an electric heating wire, a first temperature sensor, a second temperature sensor, and an electromechanical switch; The explosion-proof, flame-retardant, and heat-insulating outer shell is fitted around the outer wall of the ejector body and is slightly larger than the ejector body structure to reduce heat loss. An electric heating wire is installed in the gap, and the electric heating wire is evenly wrapped around the outer wall of the ejector body. Heat is conducted to each valve sealing ring through the metal wall surface. The first temperature sensor is located in the middle of the first proportional valve body, and the second temperature sensor is located in the middle of the second proportional valve body. Both temperature sensors are electrically connected to the controller and are used to monitor the temperature of the two proportional valves in real time. The electromechanical switch is located at the bottom of the ejector and is electrically connected to the controller to adjust the opening degree to prevent overheating. It also includes a hydrogen circulation device, which includes a gas-water separator, a drain valve, and a nitrogen discharge valve. The drain valve and the nitrogen discharge valve are located downstream of the gas-water separator and are both electrically connected to the controller.

2. The heating control device for the proton exchange membrane fuel cell ejector according to claim 1, characterized in that: The controller uses an improved PID algorithm to output the optimal power setpoint to adjust the electric heating wire. The formula for calculating the optimal power setpoint is: ； K is the control coefficient, the subscript p represents the proportional control coefficient (response speed), the subscript i represents the integral control coefficient (eliminating steady error), and the subscript d represents the derivative control coefficient (suppressing oscillation). To set the deviation between the current temperature and the set temperature, t represents the time variable; when When operating at full power, According to the formula above, when Stop working; Current traffic; This is the maximum flow rate of the ejector; Represents heating power percentage; The positive impact of the valve's self-generated heat on the percentage of heating power; The negative impact of cold hydrogen entering the ejector on the percentage of heating power; The positive effect of hydrogen entering the ejector during thermal cycling on the percentage of heating power; The controller is based on the current minimum temperature of the two proportional valves. The interval in which it is located implements a segmented control strategy: when When the heating element is at full power, the electric heating wire operates at full power; when When, calculate and output according to the above formula; when At that time, the electric heating wire stops working.

3. The heating control device for the proton exchange membrane fuel cell ejector according to claim 1, characterized in that: The gas-liquid separator consists of a rotating device and a cooling baffle. It is used to separate the mixed gas containing unreacted hydrogen, nitrogen and liquid water discharged from the anode of the fuel cell stack. The liquid water is separated by the rotating device under centrifugal force and is captured by impacting the cooling baffle. When the liquid water accumulates to the first threshold, the drain valve opens. When the nitrogen concentration in the mixed gas reaches the second threshold, the nitrogen venting valve opens. The separated hydrogen is returned to the ejector for recycling.

4. The heating control device for the proton exchange membrane fuel cell ejector according to claim 1, characterized in that: The electromechanical switch is a bimetallic strip temperature control switch or a shape memory alloy driven switch. When the temperature of the ejector body exceeds the safety threshold, it automatically cuts off or reduces the power supply of the electric heating wire. The electromechanical switch is electrically connected to the controller via a hard wire.

5. The heating control device for the proton exchange membrane fuel cell ejector according to claim 1, characterized in that: The explosion-proof, flame-retardant, and heat-insulating outer shell has a multi-layer composite structure, consisting of a high-temperature resistant ceramic fiber layer, an aerogel insulation layer, and a stainless steel protective layer from the inside out.

6. The heating control device for the proton exchange membrane fuel cell ejector according to claim 1, characterized in that: The winding density of the electric heating wire at the valve sealing ring connection of the switching valve, the first proportional valve, and the second proportional valve is 1.5-3 times that of the main body.

7. The heating control device for the proton exchange membrane fuel cell ejector according to claim 1, characterized in that: The high-pressure hydrogen source is an on-board hydrogen storage cylinder group with an outlet pressure of 35-70 MPa. After pressure reduction, it supplies hydrogen at a pressure of 0.5-2.0 MPa to the ejector.

8. The heating control device for the proton exchange membrane fuel cell ejector according to claim 1, characterized in that: The controller acquires analog signals from the first temperature sensor, the second temperature sensor, and the flow sensor through a built-in ADC module. After digital filtering, the signals are used for control calculations. The controller drives a solid-state relay through a built-in PWM timer output, which is then optocoupled and isolated to adjust the on / off duty cycle of the electric heating wire, thereby achieving continuous adjustment of the heating power.

9. The heating control device for the proton exchange membrane fuel cell ejector according to claim 1, characterized in that: The on / off valve, the first proportional valve, the second proportional valve, the drain valve, and the nitrogen discharge valve are all electrically connected to the controller via a CAN bus. The CAN bus has hardware-level error detection and priority arbitration mechanisms to ensure real-time and reliable transmission of control commands in extreme low-temperature environments.

10. A method using the heating control device for the proton exchange membrane fuel cell ejector according to claims 1-9, characterized in that: Step 1: The system is powered on and initialized. The controller acquires the real-time temperature value from the first temperature sensor. Real-time temperature value of the second temperature sensor ,Pick and the real-time flow value of the flow sensor. ; Step 2: Controller Judgment Is it within the preset traffic threshold range? If the flow rate is within the preset threshold range, it is further determined whether it meets the current low-power operating requirements. If it meets the current low-power operating requirements, it is determined that the ejector is working normally and returns to step one. If it does not meet the current low-power operating requirements, it switches to PID control mode and proceeds to step three. If the flow rate is not within the preset threshold range, it is not necessary to switch to PID control mode and proceeds directly to step three. Step 3: The controller makes further judgments. Is it below the set temperature? If yes, start the electric heating wire to heat the ejector and proceed to step four; if no, report a valve mechanical malfunction. Step 4: Set a preset interval Then, obtain the real-time traffic value again. Then return to step two for judgment until the ejector returns to normal operation or reaches the maximum heating time limit.

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