Portable hydrogen fuel cell hydrogen supply system and control method thereof

Abstract

The present application relates to the technical field of fuel cell, in particular to a portable hydrogen fuel cell hydrogen supply system and a control method thereof, comprising a fuel cell stack, a controller, a hydrogen supply system, a chargeable energy storage unit and a switch; the hydrogen supply system comprises a water storage tank, a water pump, a check valve, a hydrogen generator, a buffer tank, a first pressure sensor, a proportional valve, a second pressure sensor and a purge solenoid valve. The water in the water storage tank is injected into the hydrogen generator by the water pump, reacts with the metal hydride to generate hydrogen, and is supplied to the anode of the fuel cell stack by the proportional valve after being buffered in the buffer tank. The controller controls the start and stop of the water pump according to the detection value of the first pressure sensor to maintain the pressure of the buffer tank, and controls the opening degree of the proportional valve according to the detection value of the second pressure sensor to stabilize the pressure of the fuel cell stack, realizing double-layer decoupling control. The present application can realize accurate and stable control of the anode pressure without accurate control of the hydrogen production rate, effectively improving the portability and safety of the system.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and more specifically to a portable hydrogen fuel cell hydrogen supply system and its control method. Background Technology

[0002] With the rapid development of portable power technology for new energy sources, the demand for long-endurance, zero-pollution distributed power supply devices is continuously increasing for outdoor operations, emergency power supply, individual soldier equipment, and small mobile devices. Proton exchange membrane hydrogen fuel cells (PEMFCs) offer advantages such as high energy density and long operating time, effectively compensating for the shortcomings of lithium-ion batteries, such as short operating time and long charging time. The hydrogen supply system, as a core component of hydrogen fuel cells, directly determines the operational stability, power generation efficiency, and safety of the fuel cell stack.

[0003] Existing portable hydrogen fuel cell solutions mostly employ high-pressure gaseous hydrogen storage combined with a simple pressure reduction and regulation structure. This results in low system integration, large size and weight, making them unsuitable for lightweight, portable applications. Furthermore, conventional hydrogen supply control logic cannot accurately adjust hydrogen pressure and flow according to load changes, easily leading to unstable anode pressure. In addition, high-pressure hydrogen storage poses safety hazards for special applications such as individual soldier equipment, and refueling is difficult to achieve in field environments.

[0004] Several portable hydrogen fuel cell hydrogen supply solutions are disclosed in the prior art. For example, patent CN103579651B discloses a portable proton exchange membrane fuel cell power system. This system uses a metal hydrogen storage cylinder to store hydrogen, and the outlet of the storage cylinder is equipped with a manual pressure regulating valve. This technology uses a metal hydrogen storage cylinder, which increases material costs and safety hazards, and does not achieve automatic control of hydrogen pressure. Another example is patent CN102800875B, which discloses a portable polymer fuel cell and hydrogen production and power generation integrated system. This technology produces hydrogen by reacting aluminum metal with an alkaline solution in a reactor. A safety valve is connected to the reactor to prevent excessive instantaneous pressure. This invention uses metal hydrogen production technology to avoid the safety hazards of high-pressure hydrogen storage. However, hydrogen production requires carrying aluminum metal and an alkaline solution, increasing the burden on the user. In addition, this invention does not provide a detailed description of the hydrogen control method. Yet another example is CN108033428B, which discloses a portable hydrogen production and supply device and a hydrogen fuel cell system. The system's water pump delivers water from a water storage container to a reaction vessel, where it reacts with a hydrolyzed hydrogen production material to generate hydrogen. This invention controls the flow rate and volume of water entering the reaction vessel by adjusting the pump voltage, thereby controlling the hydrogen production rate and quantity. However, this method can only roughly control the flow rate of the reaction water and cannot precisely control the hydrogen production rate. If the hydrogen production rate does not match the hydrogen consumption rate of the fuel cell stack, the anode hydrogen pressure will become over- or under-pressured after long-term operation. Similarly, patent CN108264019A discloses a portable hydrogen production and supply device and a hydrogen fuel cell system. Water stored in an elastic water storage container can enter the reaction vessel through a water supply pipe and react with the hydrolysis hydrogen production material to produce hydrogen. This method also cannot precisely control the hydrogen production rate and poses a risk of pressure instability. Furthermore, patent CN111342080A discloses a portable fuel cell system that eliminates the hydrogen storage tank in traditional fuel cell systems, reducing the system's mass and volume, while also reducing the risk of explosion and improving safety. However, this invention does not involve a method for precise control of hydrogen pressure and flow rate.

[0005] In summary, the existing portable hydrogen fuel cell hydrogen supply system has the following technical defects: (1) using high-pressure or metal hydrogen storage cylinders to store hydrogen increases the system volume, weight, cost and safety risks; (2) using the scheme of producing hydrogen with metal and alkaline solution increases the burden on users due to the increased reactants; (3) the existing hydrogen storage cylinders and hydrogen production schemes do not involve precise control methods for hydrogen pressure and flow, and cannot achieve dynamic stability of anode pressure. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention aims to provide a portable hydrogen fuel cell hydrogen supply system. It utilizes the reaction of metal hydrides with water to produce hydrogen. The reactant water can be easily replenished outdoors where there is a water source. Users only need to carry the metal hydride, improving the system's portability. Furthermore, this system employs a hydrogen buffer tank and pressure feedback control technology, eliminating the need for precise control of the reaction water flow rate and hydrogen generation rate. Instead, it focuses on precise control of the fuel cell anode pressure, preventing excessive hydrogen generation and storage, and improving operational safety.

[0007] The basic solution provided by this invention is a portable hydrogen fuel cell hydrogen supply system, comprising a fuel cell stack, a fuel cell controller, a hydrogen supply system, a rechargeable energy storage unit, and a switch; The hydrogen supply system includes a water storage tank, a water pump, a one-way valve, a hydrogen generator, a hydrogen buffer tank, a first pressure sensor, a proportional valve, a second pressure sensor, and a purge solenoid valve. The water storage tank is used to store water, and the water storage tank is connected to the water inlet of the hydrogen generator through the water pump and the one-way valve. The hydrogen generator is used to contain metal hydrides. Water enters the hydrogen generator and reacts with the metal hydrides to generate hydrogen. The outlet of the hydrogen generator is connected to the inlet of the hydrogen buffer tank, and the outlet of the hydrogen buffer tank is connected to the anode inlet of the fuel cell stack through the proportional valve. The purge solenoid valve is installed on the anode outlet pipe of the fuel cell stack. The purge solenoid valve is used to control the opening and closing of the anode outlet. The first pressure sensor is installed on the hydrogen buffer tank and is used to detect the hydrogen pressure inside the tank; The second pressure sensor is installed on the pipeline between the proportional valve and the fuel cell stack to detect the hydrogen pressure entering the stack. The fuel cell controller has a power input interface and a power output interface. The power input interface is connected to the fuel cell stack, and the power output interface is connected to the rechargeable energy storage unit through the switch. The rechargeable energy storage unit is used to provide system startup power and instantaneous load power. The fuel cell controller is connected to the water pump, the proportional valve, the purge solenoid valve, the first pressure sensor, and the second pressure sensor respectively. It is used to control the start and stop of the water pump according to the detection value of the first pressure sensor, to control the opening degree of the proportional valve in a closed loop according to the detection value of the second pressure sensor, and to control the opening or closing of the purge solenoid valve.

[0008] Furthermore, the fuel cell controller controls the water pump to start when the pressure value detected by the first pressure sensor is lower than a preset lower threshold, and controls the water pump to stop after a preset time has elapsed since the water pump started or when the pressure value detected by the first pressure sensor is higher than a preset upper threshold.

[0009] Furthermore, the metal hydride is calcium hydride.

[0010] Furthermore, the rechargeable energy storage unit is a lithium battery pack.

[0011] Furthermore, the fuel cell controller includes a microcontroller, a power input interface, a power output interface, a relay, a programmable DC / DC converter, a voltage monitoring module, a signal input / output module, and a controller power supply module; The microcontroller is connected to the water pump, the proportional valve, the purge solenoid valve, the first pressure sensor, and the second pressure sensor via the signal input / output module. The voltage monitoring module is used to detect the voltage of each cell in the fuel cell stack. The programmable DC / DC converter is used to control the output current of the fuel cell stack according to the instructions of the microcontroller.

[0012] The principle of this invention lies in decoupling the hydrogen production side from the hydrogen supply side to achieve precise control of the hydrogen pressure at the fuel cell anode, thereby improving the portability and safety of the system, as detailed below: When the system is working, the rechargeable energy storage unit (such as a lithium battery pack) first provides starting power for the fuel cell controller and auxiliary equipment such as water pumps. The fuel cell controller controls the water pump to inject water from the storage tank into the hydrogen generator in a metered manner. The water reacts chemically with metal hydrides (such as calcium hydride) to produce hydrogen. The produced hydrogen enters the hydrogen buffer tank for buffering and gas-liquid separation. The separated hydrogen is then transported to the anode of the fuel cell stack after being pressure regulated by a proportional valve.

[0013] In terms of control strategy, this invention constructs a two-layer control architecture for the hydrogen production side and the hydrogen supply side. Specifically: Hydrogen production side control: A first pressure sensor monitors the hydrogen pressure in the hydrogen buffer tank in real time. When the pressure in the tank falls below a preset lower threshold (e.g., 100 kPa), the fuel cell controller controls the water pump to start for a preset duration to replenish water, restoring the hydrogen pressure in the buffer tank to a preset maximum operating pressure (e.g., 400 kPa). The water pump stops after the preset duration or when the pressure in the tank exceeds a preset upper threshold. This hysteresis control strategy ensures that the water pump only starts replenishing water when the pressure reaches the lower limit, significantly reducing the pump's start-stop frequency, extending its lifespan, and making the hydrogen production side insensitive to load changes, resulting in strong system robustness.

[0014] Hydrogen supply side control section: The second pressure sensor is set between the proportional valve and the fuel cell stack to detect the hydrogen pressure entering the stack in real time. The fuel cell controller continuously adjusts the opening of the proportional valve in a closed-loop manner according to the real-time feedback value of the second pressure sensor, so that the hydrogen pressure entering the stack is accurately and stably maintained at the set value (such as 50 kPa), unaffected by pressure fluctuations in the buffer tank.

[0015] The hydrogen buffer tank, acting as an intermediary between the hydrogen production and supply sides, plays a crucial role in decoupling the hydrogen production rate from the hydrogen consumption rate. Specifically, the buffer tank's volume absorbs the rate difference between the two, allowing the intermittent water pump replenishment control and the continuous pressure regulation control of the proportional valve to operate independently without interference. The water pump no longer needs to frequently start and stop to adapt to load changes, and the proportional valve no longer needs to cope with drastic fluctuations in the hydrogen production rate. This decoupling architecture overcomes the technical limitations of existing technologies that require precise control of the hydrogen production rate to match the hydrogen consumption rate, achieving high-precision and stable control of the anode pressure without relying on high-precision flow control.

[0016] Furthermore, this invention accurately calculates the total amount of hydrogen required before system startup using Faraday's law, and then precisely calculates the required mass of metal hydride and the volume of water based on the chemical reaction equation. Users only need to carry the calculated amount of metal hydride; water can be replenished locally at outdoor water sources. There is no need to carry alkaline solutions or other auxiliary reactants, significantly reducing the carrying burden. During shutdown, a programmable DC / DC converter controls the fuel cell stack to discharge with a small current, actively consuming any remaining hydrogen in the system until the individual cell voltage drops below a safe threshold, ensuring no hydrogen remains in the system after shutdown and eliminating the safety hazard of hydrogen leakage.

[0017] Compared to existing technologies, this invention eliminates the need for high-pressure or metal hydrogen storage cylinders, fundamentally eliminating the risk of high-pressure hydrogen leakage or explosion. Simultaneously, it controls the system operating pressure far below the safe range of high-pressure hydrogen storage (the buffer tank's maximum operating pressure is only 400 kPa, and the pressure from the proportional valve outlet to the stack anode is typically in the range of 50-100 kPa). Even in the event of a leak under abnormal conditions, the damage is far less than that of a high-pressure hydrogen storage system. Furthermore, it overcomes the deficiency in existing hydrogen production methods that cannot precisely control the anode pressure, providing a safe, lightweight, and precisely controllable hydrogen supply solution for portable hydrogen fuel cells.

[0018] The beneficial effects of this invention are as follows: 1. Hydrogen production is achieved through the reaction of metal hydrides with water. Users only need to carry solid metal hydrides, and water can be obtained locally outdoors. There is no need to carry auxiliary reactants such as alkaline solutions, significantly reducing the system weight and carrying burden. At the same time, the system's operating pressure is much lower than that of traditional high-pressure hydrogen storage solutions (the maximum operating pressure of the buffer tank is only 400 kPa, and the pressure from the proportional valve outlet to the stack anode is usually in the range of 50~100 kPa), eliminating the risk of high-pressure hydrogen leakage or explosion; when shutting down, residual hydrogen is consumed through active discharge, improving operational safety.

[0019] 2. A dual-layer decoupled architecture, employing buffer tank pressure hysteresis control and proportional valve closed-loop feedback control, achieves precise and stable control of the hydrogen inlet pressure. Specifically, the buffer tank decouples the hydrogen production side from the hydrogen supply side, allowing the intermittent water replenishment control of the pump and the continuous pressure regulation control of the proportional valve to operate independently without interference. This maintains the anode inlet pressure precisely at the set value without relying on high-precision flow control. Simultaneously, the pump employs a hysteresis control strategy, resulting in extremely low start-stop frequency, extending pump lifespan, and demonstrating strong robustness to fluctuations in the hydrogen production rate.

[0020] 3. The rechargeable energy storage unit provides the system with startup power and instantaneous load power, ensuring reliable startup of the system in a cold state and providing instantaneous power supplementation when the load power changes suddenly, ensuring the continuity of power supply. The entire energy conversion process is clean and pollution-free, that is, the products of the reaction between metal hydride and water are metal hydroxide and hydrogen. Hydrogen reacts in the fuel cell to produce water, with no harmful emissions.

[0021] Correspondingly, the present invention also discloses a control method for the above-mentioned portable hydrogen fuel cell hydrogen supply system, comprising the following steps: S1: Based on the target output current, number of single battery cells and target operating time, calculate the required molar amount of hydrogen using Faraday's law, and then calculate the required mass of metal hydride and the required volume of water based on the chemical reaction equation. S2: Add the calculated mass of metal hydride to the hydrogen generator and the calculated volume of water to the water storage tank; S3: When the switch is closed, the controller power module outputs a stable DC power, and the fuel cell controller starts working. S4: The fuel cell controller controls the proportional valve and purge solenoid valve to open, controls the water pump to start for a preset time to inject water into the hydrogen generator, and controls the air supply to the stack cathode. The preset time is calculated based on the volume of the hydrogen buffer tank and the preset maximum working pressure, so that the hydrogen pressure in the hydrogen buffer tank reaches the preset maximum working pressure after a single water injection. S5: Determine whether the minimum single cell voltage of the fuel cell stack is higher than the preset open circuit voltage threshold. If not, return to step S4 to continue feeding hydrogen and air into the stack. If yes, confirm that the fuel cell stack has established an open circuit voltage. S6: Determine whether the system has received a shutdown command. If yes, proceed to step S11; otherwise, proceed to step S7. S7: The fuel cell controller controls the purge solenoid valve to open in a periodic pulse manner, and the proportional valve adjusts its opening degree according to the set hydrogen pressure value and the feedback value of the second pressure sensor, while controlling the output current of the fuel cell stack to the target output current. S8: Determine whether the hydrogen pressure detected by the first pressure sensor in the hydrogen buffer tank is less than the preset lower threshold. If not, return to step S6. S9: The fuel cell controller controls the water pump to start for the preset duration to replenish water; S10: After a preset delay, return to step S6; S11: The fuel cell controller stops the water pump and closes the proportional valve and purge solenoid valve, thus stopping hydrogen from entering the anode channel of the fuel cell stack. S12: Control the fuel cell stack to discharge at a preset discharge current, consuming the hydrogen remaining in the fuel cell stack. S13: Determine whether the minimum single cell voltage of the fuel cell stack is less than the preset shutdown threshold. If not, return to step S12 to continue discharging. S14: Control the output current of the programmable DC / DC converter to zero, and the system will stop.

[0022] Furthermore, in step S1, the metal hydride is calcium hydride, and the formula for calculating the required molar amount of hydrogen is as follows:

[0023] in, The required molar amount of hydrogen. The target output current, The number of cells in the single battery cell. The target running time, It is Faraday's constant; The chemical reaction equation is as follows:

[0024] The required mass of calcium hydride is obtained based on the reaction formula. The volume of water required is grams. milliliters.

[0025] Furthermore, the method for calculating the preset duration is as follows: According to the ideal gas law Calculate the amount of hydrogen moles that the hydrogen buffer tank can store at the preset maximum operating pressure. In the formula The preset maximum working pressure, The volume of the hydrogen buffer tank. The gas constant is... The gas temperature; The molar amount of hydrogen gas is determined according to the chemical reaction equation. Convert to the required volume of water; According to the flow rate of the water pump Convert the required water volume into time.

[0026] The above control method achieves safe, stable, and efficient operation of the portable hydrogen production fuel cell system under conditions where precise control of the hydrogen production rate is not required through the coordinated operation of six stages: material feedforward calculation, system power-on and start-up preparation, constant volume water replenishment, start-up pressure build-up judgment, normal operation adjustment and hysteresis water replenishment coordination, and safe shutdown. The details are as follows: Steps S1 to S2 constitute the material feedforward calculation stage: using Faraday's law to accurately calculate the total amount of hydrogen required during the operating time, and then using the stoichiometric ratio of the chemical reaction equation to calculate the required mass of metal hydride and the volume of water, ensuring that the amount of material added just meets the needs of the entire operating period. This avoids both the interruption of operation due to insufficient material and the waste caused by excessive material and the potential safety hazards caused by residual reactants after shutdown.

[0027] Step S3 is the system power-on and startup preparation stage: by closing the switch, the rechargeable energy storage unit is connected to the system, and the controller power module converts the bus voltage into stable DC power to provide working power for the fuel cell controller and its various functional modules.

[0028] Step S4 is the constant-volume water replenishment process: The fuel cell controller first controls the proportional valve and purge solenoid valve to open, ensuring unobstructed hydrogen flow. Then, it controls the water pump to operate for a preset duration to inject water into the hydrogen generator. This preset duration is calculated based on the ideal gas law, the volume of the hydrogen buffer tank, and the preset maximum operating pressure, ensuring that each water replenishment precisely restores the buffer tank pressure from a lower level to the preset maximum operating pressure. This quantitative control method of hydrogen production based on tank volume ensures precise control over hydrogen production, avoiding potential safety hazards caused by excessive hydrogen production.

[0029] Step S5 is the start-up pressure judgment step: by judging whether the lowest single cell voltage is higher than the preset open circuit voltage threshold (such as 1.2V), it is confirmed whether the fuel cell stack has successfully established an open circuit voltage, ensuring that the system enters normal operation only after the stack has the ability to generate electricity; if the pressure is not established, return to step S4 to continue to introduce hydrogen and air into the stack, and wait for the open circuit voltage to continue to rise until the condition is met.

[0030] Steps S6-S10 constitute the normal operation collaborative control loop, which includes three parallel sub-logic: First, step S6 continuously monitors shutdown commands to ensure the system can respond to the operator's shutdown request in a timely manner; Second, step S7 performs regulation and anode management: the proportional valve continuously adjusts its opening in a closed-loop manner based on the real-time feedback value of the second pressure sensor to accurately stabilize the hydrogen pressure entering the reactor at the set value, while the purge solenoid valve opens periodically in a pulse manner (closed most of the time, periodically opened briefly), ensuring that the anode is in a dead-end state to improve hydrogen utilization, while periodically discharging the liquid water accumulated in the anode channel and the nitrogen permeating from the cathode to prevent the reactor stack performance degradation caused by the accumulation of liquid water and nitrogen; Third, steps S8-S10 perform hysteresis water replenishment control: when the buffer tank pressure is lower than the preset lower limit threshold, water replenishment is initiated, and after water replenishment, a preset time is delayed to wait for the pressure to stabilize before returning to the main loop for judgment. This hysteresis control strategy ensures that the pump only starts when the pressure reaches the lower limit, resulting in an extremely low start-stop frequency that is independent of load changes. This extends the pump's lifespan and also makes the system highly robust to fluctuations in the hydrogen production rate.

[0031] Steps S11-S14 constitute the safe shutdown process: First, the hydrogen supply is cut off (the water pump, proportional valve, and purge solenoid valve are shut down). Then, the fuel cell stack is controlled by a programmable DC / DC converter to discharge at a preset small current, actively consuming the residual hydrogen in the pipes and anode channels until the cell voltage drops below the preset shutdown threshold. Finally, the output is completely cut off. This active residual hydrogen consumption strategy ensures that there is no residual hydrogen in the system after shutdown, eliminating the safety hazard of hydrogen leakage, and avoiding the hazards such as reverse polarity or corrosion caused by residual hydrogen inside the fuel cell stack after shutdown. Attached Figure Description

[0032] Figure 1 This is a system block diagram of an embodiment of a portable hydrogen fuel cell hydrogen supply system according to the present invention.

[0033] Figure 2 This is a flowchart of a control method for a portable hydrogen fuel cell hydrogen supply system according to the present invention.

[0034] The reference numerals in the accompanying drawings include: fuel cell stack 1, fuel cell controller 2; microcontroller 201, power input interface 202, power output interface 203, relay 204, programmable DC / DC converter 205, voltage monitoring module 206, signal input / output module 207, controller power module 208, hydrogen supply system 3, water tank 301, water pump 302, one-way valve 303, hydrogen generator 304, calcium hydride powder 305, discharge port 306, hydrogen buffer tank 307, drain port 308, first pressure sensor 309, proportional valve 310, second pressure sensor 311, purge solenoid valve 312, rechargeable energy storage unit 4, switch 401, load 402. Detailed Implementation

[0035] The following detailed description illustrates the specific implementation method: The basic implementation examples are as follows: Figure 1 As shown: A portable hydrogen fuel cell hydrogen supply system includes a fuel cell stack 1, a fuel cell controller 2, a hydrogen supply system 3, a rechargeable energy storage unit 4, and a switch 401.

[0036] The hydrogen supply system 3 includes a water storage tank 301, a water pump 302, a one-way valve 303, a hydrogen generator 304, a discharge port 306, a hydrogen buffer tank 307, a drain port 308, a first pressure sensor 309, a proportional valve 310, a second pressure sensor 311, and a purge solenoid valve 312.

[0037] The water storage tank 301 is used to store water, and it is connected to the inlet of the hydrogen generator 304 via the water pump 302 and the one-way valve 303. The one-way valve 303 is used to prevent hydrogen generated in the hydrogen generator 304 from flowing back into the water storage tank 301 along the water supply channel.

[0038] The hydrogen generator 304 is used to contain the metal hydride. Water enters the hydrogen generator 304 and reacts with the metal hydride to generate hydrogen. A discharge port 306 is provided on the hydrogen generator 304 for discharging waste materials after the reaction and adding new metal hydride. In this embodiment, the metal hydride is preferably calcium hydride powder 305. It should be noted that the metal hydride described in this invention refers to a metal hydride that reacts stably with water and whose hydrogen production rate can be controlled by controlling the amount of water injected. Those skilled in the art will understand that other metal hydrides that react stably with water and have a controllable hydrogen production rate can also be used to implement this invention using the same system architecture and control logic.

[0039] The outlet of the hydrogen generator 304 is connected to the inlet of the hydrogen buffer tank 307, and the outlet of the hydrogen buffer tank 307 is connected to the anode inlet of the fuel cell stack 1 via the proportional valve 310. The hydrogen buffer tank 307 is used to store the hydrogen generated by the reaction and to separate liquid water. The separated hydrogen flows out from the outlet pipe located above the hydrogen buffer tank 307. A drain outlet 308 is provided on the hydrogen buffer tank 307.

[0040] The anode outlet pipe of the fuel cell stack 1 is equipped with the purge solenoid valve 312, which is used to control the opening and closing of the anode outlet. During normal operation, the fuel cell controller 2 controls the purge solenoid valve 312 to open in a periodic pulse manner: it is closed most of the time to keep the anode in a dead end state to improve hydrogen utilization, and it is opened briefly periodically to discharge liquid water and nitrogen accumulated in the anode channel.

[0041] The first pressure sensor 309 is mounted on the hydrogen buffer tank 307 to detect the hydrogen pressure inside the tank and feed it back to the fuel cell controller 2. The fuel cell controller 2 controls the start and stop of the water pump 302 based on the detection value of the first pressure sensor 309: when the pressure value detected by the first pressure sensor 309 is lower than a preset lower threshold (e.g., 100 kPa), the water pump 302 is turned on; when the detected pressure value is higher than a preset upper threshold (e.g., 400 kPa), the water pump 302 is stopped. This hysteresis control strategy ensures that the water pump 302 only starts replenishing water when the pressure reaches the lower limit, significantly reducing the start and stop frequency of the water pump 302.

[0042] The second pressure sensor 311 is installed on the pipeline between the proportional valve 310 and the fuel cell stack 1, and is used to detect the hydrogen pressure entering the stack and feed it back to the fuel cell controller 2. The fuel cell controller 2 controls the opening of the proportional valve 310 in a closed loop based on the real-time feedback value of the second pressure sensor 311, so that the hydrogen pressure entering the stack is maintained at a set value. It should be noted that the feedback signal on which the closed-loop control of the proportional valve 310 is based comes from the second pressure sensor 311 (not the first pressure sensor 309 installed on the buffer tank). The first pressure sensor 309 is used to control the start and stop of the water pump 302, and the functions of the two are clearly defined.

[0043] The fuel cell controller 2 includes a microcontroller 201, a power input interface 202, a power output interface 203, a relay 204, a programmable DC / DC converter 205, a voltage monitoring module 206, a signal input / output module 207, and a controller power module 208. The power input interface 202 is connected to the fuel cell stack 1. The power output interface 203 is connected to the rechargeable energy storage unit 4 via a switch 401 and is directly connected to the load 402. The rechargeable energy storage unit 4 provides system startup power and instantaneous power to the load 402. The switch 401 controls the connection between the power output interface 203 and the rechargeable energy storage unit 4. The microcontroller 201 is the core of the system, responsible for input acquisition, output driving, logic control, protection judgment, and communication storage. The relay 204 controls the connection between the power input interface 202 and the programmable DC / DC converter 205; its switching state is controlled by the microcontroller 201. The programmable DC / DC converter 205 controls the output current of the fuel cell stack 1 according to the instructions of the microcontroller 201. The voltage monitoring module 206 detects the voltage of each cell in the fuel cell stack 1 and transmits the cell voltage information to the microcontroller 201. The signal input / output module 207 receives signals from external sensors (including signals from the first pressure sensor 309 and the second pressure sensor 311) and sends them to the microcontroller 201, and outputs control signals according to the instructions of the microcontroller 201 to drive valves (including proportional valve 310 and purge solenoid valve 312) and water pump 302 to perform actions. The controller power supply module 208 converts the unstable DC voltage on the bus into stable DC voltage (such as 12V) to provide operating power for the fuel cell controller 2.

[0044] In this embodiment, the rechargeable energy storage unit 4 is a lithium battery pack, used to provide system startup power and instantaneous power for load 402. It should be noted that the rechargeable energy storage unit described in this invention is not limited to lithium battery packs; other energy storage devices capable of energy storage and power supply functions (such as lead-acid batteries, nickel-metal hydride batteries, supercapacitors, etc.) can be used as substitutes.

[0045] The fuel cell controller 2 is connected to the water pump 302, the proportional valve 310, the purge solenoid valve 312, the first pressure sensor 309, and the second pressure sensor 311, respectively.

[0046] As attached Figure 2 As shown, the control method for the aforementioned portable hydrogen fuel cell hydrogen supply system includes the following steps: S1: Based on the target output current, number of single battery cells, and target operating time, calculate the required molar amount of hydrogen using Faraday's law, and then calculate the required mass of metal hydride and the required volume of water based on the chemical reaction equation.

[0047] In this embodiment, the metal hydride is calcium hydride, and the formula for calculating the required molar amount of hydrogen is as follows:

[0048] in, The required molar amount of hydrogen. The target output current, The number of cells in the single battery cell. The target running time, It is Faraday's constant; The chemical equation for the reaction of calcium hydride with water is:

[0049] Based on the reaction equation, the required mass of calcium hydride is: The volume of water required is grams. milliliters.

[0050] S2: Add the calculated mass of metal hydride (calcium hydride powder 305 in this embodiment) to the hydrogen generator 304, and add the calculated volume of water to the water storage tank 301.

[0051] S3: When switch 401 is closed, the controller power module 208 outputs a stable DC power (such as 12V), and the fuel cell controller 2 starts to work.

[0052] S4: The fuel cell controller 2 controls the proportional valve 310 and the purge solenoid valve 312 to open, ensuring unobstructed hydrogen flow; it also controls the water pump 302 to open for a preset time. Water is injected into the hydrogen generator 304; air supply is controlled to the cathode of the fuel cell stack. The preset duration... The calculation is based on the volume of the hydrogen buffer tank 307 and the preset maximum working pressure, so that the hydrogen pressure in the hydrogen buffer tank 307 reaches the preset maximum working pressure after a single water injection.

[0053] In this embodiment, the preset maximum working pressure is 400 kPa, and the preset duration is... The calculation method is as follows: based on the ideal gas law Calculate the hydrogen buffer tank 307 at the preset maximum working pressure. The amount of hydrogen that can be stored at (400 kPa) In the formula The volume of hydrogen buffer tank 307. The gas constant is 8.314 J / mol. -1 k -1 T is the gas temperature (e.g., 298K); the molar amount of hydrogen is determined according to the chemical reaction equation. Converted to the required volume of water (18) (ml); based on the flow rate of water pump 302 (mL / s) converts the required water volume into time, i.e. .

[0054] S5: Determine whether the lowest single-cell voltage of fuel cell stack 1 is higher than the preset open-circuit voltage threshold (e.g., 1.2V). If not, return to step S4 to continue feeding hydrogen and air into the stack; if yes, confirm that fuel cell stack 1 has established an open-circuit voltage and the system is ready to enter normal operation.

[0055] S6: Determine whether the system has received a stop command (e.g., by detecting the on / off signal of a key switch). If yes, proceed to step S11; otherwise, proceed to step S7.

[0056] S7: The fuel cell controller 2 controls the purge solenoid valve 312 to open periodically in a pulsed manner (closed most of the time, periodically opened briefly) to discharge the liquid water and nitrogen accumulated in the anode channel; the proportional valve 310 adjusts its opening degree according to the set hydrogen pressure value and the feedback value of the second pressure sensor 311 to make the hydrogen pressure entering the stack precisely stable at the set value (e.g., 50 kPa); at the same time, the fuel cell controller 2 controls the output current of the fuel cell stack 1 to the target output current. .

[0057] S8: Determine whether the hydrogen pressure detected by the first pressure sensor 309 in the hydrogen buffer tank 307 is less than a preset lower threshold (e.g., 100 kPa). If not, return to step S6; if yes, proceed to step S9.

[0058] S9: The fuel cell controller 2 controls the water pump 302 to start for the preset duration. To replenish water, the hydrogen pressure in the buffer tank is restored to the preset maximum working pressure. It should be noted that the preset duration in step S4... Compared with the preset duration in step S9 The same duration value is calculated based on the same buffer tank volume and preset maximum working pressure.

[0059] S10: After a preset delay (e.g., 1 minute), return to step S6.

[0060] S11: The fuel cell controller 2 controls the water pump 302 to stop working, controls the proportional valve 310 and the purge solenoid valve 312 to close, so that hydrogen stops entering the anode flow channel of the fuel cell stack 1.

[0061] S12: Control the fuel cell stack 1 to discharge at a preset discharge current (e.g., 0.5A) to consume the hydrogen remaining in the fuel cell stack 1.

[0062] S13: Determine whether the lowest single-cell voltage of fuel cell stack 1 is less than the preset shutdown threshold (e.g., 0.4V). If not, return to step S12 to continue discharging; if yes, the discharge ends and proceed to step S14.

[0063] S14: Control the output current of the programmable DC / DC converter 205 to zero, and the system will stop.

[0064] The above are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A portable hydrogen fuel cell hydrogen supply system, characterized in that, This includes fuel cell stacks, fuel cell controllers, hydrogen supply systems, rechargeable energy storage units, and switches; The hydrogen supply system includes a water storage tank, a water pump, a one-way valve, a hydrogen generator, a hydrogen buffer tank, a first pressure sensor, a proportional valve, a second pressure sensor, and a purge solenoid valve. The water storage tank is used to store water, and the water storage tank is connected to the water inlet of the hydrogen generator through the water pump and the one-way valve. The hydrogen generator is used to contain metal hydrides. Water enters the hydrogen generator and reacts with the metal hydrides to generate hydrogen. The outlet of the hydrogen generator is connected to the inlet of the hydrogen buffer tank, and the outlet of the hydrogen buffer tank is connected to the anode inlet of the fuel cell stack through the proportional valve. The purge solenoid valve is installed on the anode outlet pipe of the fuel cell stack. The purge solenoid valve is used to control the opening and closing of the anode outlet. The first pressure sensor is installed on the hydrogen buffer tank and is used to detect the hydrogen pressure inside the tank; The second pressure sensor is installed on the pipeline between the proportional valve and the fuel cell stack to detect the hydrogen pressure entering the stack. The fuel cell controller has a power input interface and a power output interface. The power input interface is connected to the fuel cell stack, and the power output interface is connected to the rechargeable energy storage unit through the switch. The rechargeable energy storage unit is used to provide system startup power and instantaneous load power. The fuel cell controller is connected to the water pump, the proportional valve, the purge solenoid valve, the first pressure sensor, and the second pressure sensor respectively. It is used to control the start and stop of the water pump according to the detection value of the first pressure sensor, to control the opening degree of the proportional valve in a closed loop according to the detection value of the second pressure sensor, and to control the opening or closing of the purge solenoid valve.

2. The portable hydrogen fuel cell hydrogen supply system according to claim 1, characterized in that, The fuel cell controller controls the water pump to start when the pressure value detected by the first pressure sensor is lower than a preset lower threshold, and controls the water pump to stop after a preset time has elapsed since the water pump started or when the pressure value detected by the first pressure sensor is higher than a preset upper threshold.

3. The portable hydrogen fuel cell hydrogen supply system according to claim 1, characterized in that, The metal hydride is calcium hydride.

4. The portable hydrogen fuel cell hydrogen supply system according to claim 1, characterized in that, The rechargeable energy storage unit is a lithium battery pack.

5. The portable hydrogen fuel cell hydrogen supply system according to claim 1, characterized in that, The fuel cell controller includes a microcontroller, a power input interface, a power output interface, a relay, a programmable DC / DC converter, a voltage monitoring module, a signal input / output module, and a controller power supply module. The microcontroller is connected to the water pump, the proportional valve, the purge solenoid valve, the first pressure sensor, and the second pressure sensor via the signal input / output module. The voltage monitoring module is used to detect the voltage of each cell in the fuel cell stack. The programmable DC / DC converter is used to control the output current of the fuel cell stack according to the instructions of the microcontroller.

6. A control method for a portable hydrogen fuel cell hydrogen supply system as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1: Based on the target output current, number of single battery cells and target operating time, calculate the required molar amount of hydrogen using Faraday's law, and then calculate the required mass of metal hydride and the required volume of water based on the chemical reaction equation. S2: Add the calculated mass of metal hydride to the hydrogen generator and the calculated volume of water to the water storage tank; S3: When the switch is closed, the controller power module outputs a stable DC power, and the fuel cell controller starts working. S4: The fuel cell controller controls the proportional valve and purge solenoid valve to open, controls the water pump to start for a preset time to inject water into the hydrogen generator, and controls the air supply to the stack cathode. The preset time is calculated based on the volume of the hydrogen buffer tank and the preset maximum working pressure, so that the hydrogen pressure in the hydrogen buffer tank reaches the preset maximum working pressure after a single water injection. S5: Determine whether the minimum single cell voltage of the fuel cell stack is higher than the preset open circuit voltage threshold. If not, return to step S4 to continue feeding hydrogen and air into the stack. If yes, confirm that the fuel cell stack has established an open circuit voltage. S6: Determine if the system has received a shutdown command. If so, proceed to step S11. Otherwise, proceed to step S7; S7: The fuel cell controller controls the purge solenoid valve to open in a periodic pulse manner, and the proportional valve adjusts its opening degree according to the set hydrogen pressure value and the feedback value of the second pressure sensor, while controlling the output current of the fuel cell stack to the target output current. S8: Determine whether the hydrogen pressure detected by the first pressure sensor in the hydrogen buffer tank is less than the preset lower threshold. If not, return to step S6. S9: The fuel cell controller controls the water pump to start for the preset duration to replenish water; S10: After a preset delay, return to step S6; S11: The fuel cell controller stops the water pump and closes the proportional valve and purge solenoid valve, thus stopping hydrogen from entering the anode channel of the fuel cell stack. S12: Control the fuel cell stack to discharge at a preset discharge current, consuming the hydrogen remaining in the fuel cell stack. S13: Determine whether the minimum single cell voltage of the fuel cell stack is less than the preset shutdown threshold. If not, return to step S12 to continue discharging. S14: Control the output current of the programmable DC / DC converter to zero, and the system will stop.

7. The control method according to claim 6, characterized in that, In step S1, the metal hydride is calcium hydride, and the formula for calculating the required molar amount of hydrogen is: in, The required molar amount of hydrogen. The target output current, The number of cells in the single battery cell. The target running time, It is Faraday's constant; The chemical reaction equation is as follows: The required mass of calcium hydride is obtained based on the reaction formula. The volume of water required is grams. milliliters.

8. The control method according to claim 6, characterized in that, The method for calculating the preset duration is as follows: According to the ideal gas law Calculate the amount of hydrogen moles that the hydrogen buffer tank can store at the preset maximum operating pressure. In the formula The preset maximum working pressure, The volume of the hydrogen buffer tank. The gas constant is... The gas temperature; The molar amount of hydrogen gas is determined according to the chemical reaction equation. Convert to the required volume of water; According to the flow rate of the water pump Convert the required water volume into time.

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