Hydraulic pressure maintaining system for galvanic pile of high-pressure water electrolyser and control method

Abstract

The invention discloses a hydraulic pressure maintaining system for an electric pile of a high-pressure water electrolyser and a control method, and belongs to the technical field of new energy and high-efficiency energy conservation. The system comprises a water electrolyser galvanic pile, a hydraulic system, a sensing unit and a control unit. The hydraulic system is used for applying adjustable clamping force to the electric pile of the water electrolyser; the sensing unit acquires a contact resistance signal and a back pressure signal of the electric pile in real time; the control unit receives the signals, adjusts the output pressure of the hydraulic system, and maintains the effective contact pressure of the galvanic pile. The hydraulic system comprises a structural assembly and a hydraulic driving assembly, wherein the hydraulic driving assembly comprises a hydraulic cylinder, a hydraulic pump, an oil tank, an electromagnetic valve and the like. The control method comprises the three steps of collecting parameters in real time, calculating a target pressure value and controlling the hydraulic system to apply corresponding clamping force, and pressure adjustment is divided into a pressure increasing stage, a pressure maintaining stage and a pressure reducing stage. The clamping force can be automatically adjusted according to the running state of the galvanic pile, and the problem that the sealing performance and contact resistance of the galvanic pile change in the high-pressure water electrolysis process is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of new energy and energy-efficient technology, specifically to a hydraulic pressure-maintaining system and control method for a high-pressure water electrolyzer stack. Background Technology

[0002] Global energy development is transitioning towards a green and low-carbon model. New energy technologies, as the core force of this transition, are essential for humanity to address energy security, environmental pollution, and climate change. They are also a key driver of global energy transition and sustainable economic and social development. While my country has made significant achievements in several fields, including solar energy and hydrogen energy storage, it also faces challenges such as the lack of independent control over some core technologies and resource dependence.

[0003] During operation of the fuel cell stack, the solubility of gas in the liquid increases with increasing pressure. However, the situation is more complex in the micropores of the porous transport layer and catalyst layer of a PEMWE (proton exchange membrane electrolyzer). When the system operates at very high back pressures (e.g., above 30 bar), the gas in the electrolyte may reach a supersaturated state. These bubbles expand in volume during nucleation, growth, and merging. These bubbles generated on the pore surface exert a thrust on the porous transport layer above, and even the entire membrane electrode and bipolar plate, causing the internal structure of the fuel cell stack to be "spread out." The fuel cell stack is assembled by applying a huge clamping force to the end plates to ensure good contact and minimal resistance between the components. However, the thrust generated by the gas under high back pressure will offset part of the effective clamping force, resulting in a decrease in the actual effective contact pressure between the components. Furthermore, insufficient effective contact pressure will lead to increased contact resistance, causing a decrease in the performance of the water electrolyzer and even damage and leakage. Moreover, insufficient effective contact pressure may also make it easier for impurities or moisture to accumulate at the contact interface, further increasing the interfacial resistance.

[0004] Currently, many pressure holding and clamping devices for fuel cell stacks are available on the market. Traditional clamping devices utilize end plates and multiple screws to provide clamping force, and spring washers to apply preload torque. However, controlling the preload is difficult, and it is susceptible to loosening due to temperature changes and vibration, leading to increased contact resistance and performance degradation. Furthermore, it is difficult to ensure uniform pressure throughout large fuel cell stacks, easily resulting in "edge effects" or localized stress concentrations. While integrally packaged clamping devices allow for fixed-size assembly, they lack flexibility, cannot handle different fuel cell stack assemblies, and have poor maintainability. Therefore, based on existing technology, there is a need to design a more precise, dynamically adjustable hydraulic pressure holding system, along with auxiliary systems such as hydraulic pumps, solenoid valves, and external piping, to meet the testing performance and lifespan requirements of fuel cell stacks and promote research into related mechanisms. Summary of the Invention

[0005] The purpose of this invention is to address the common problems in existing fuel cell stack clamping devices, such as difficulty in controlling preload force, uneven stress distribution, poor stability, low flexibility, and difficulty in handling internal gas expansion in high-back-pressure water electrolyzers. Combining the advantages of hydraulic mechanisms, this invention proposes a novel hydraulic pressure-holding system and control method for high-pressure water electrolyzer fuel cell stacks. This system can apply a uniform clamping force to the fuel cell stack, and the contact pressure can be precisely and flexibly adjusted and locked within a certain range. When the fuel cell stack is running stably, the increased contact resistance due to internal gas expansion can be effectively increased by the system through PID control. When the back pressure of the fuel cell stack is reduced by the operator, the system can effectively reduce the pressure, thereby achieving automatic adjustment of the hydraulic system pressure and ensuring that the fuel cell stack is in good working condition.

[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: In a first aspect, the present invention provides a hydraulic pressure-maintaining system for a high-pressure water electrolyzer stack, comprising: Electrolytic cell stack; A hydraulic system for applying an adjustable clamping force to the water electrolyzer stack; The sensing unit is used to collect the contact resistance signal and back pressure signal of the water electrolyzer stack in real time. The control unit is electrically connected to the hydraulic system and the sensing unit respectively. The control unit receives the contact resistance signal and the back pressure signal and is used to adjust the output pressure of the hydraulic system to maintain the effective contact pressure of the water electrolyzer stack.

[0007] As a preferred embodiment of the present invention, the water electrolysis cell stack includes an electrolysis cell, an upper end plate, a lower end plate, and a support screw. The bottom end of the support screw is fixedly connected to the lower end plate, and its top end extends upward through the upper end plate and is equipped with a nut. The distance between the upper end plate and the lower end plate is adjustable.

[0008] As a preferred embodiment of the present invention, the back pressure signal is acquired from the back pressure of the cathode outlet of the upper end plate, and the sensing unit includes a back pressure sensor adapted to the cathode outlet. The back pressure sensor is used to display and feed back the back pressure value to the control unit.

[0009] As a preferred embodiment of the present invention, the sensing unit further includes a contact resistance sensor, which is electrically connected to the current collector of the electrolytic cell via an electrode tab, and is used to collect the contact resistance signal of the water electrolytic cell stack and transmit it to the control unit.

[0010] As a preferred embodiment of the present invention, the hydraulic system includes a structural component and a hydraulic drive component. The structural component includes a chassis, a column fixed on the chassis, and a lifting platform disposed on the column. The water electrolyzer stack is placed on the chassis. The hydraulic drive component is used to apply an adjustable clamping force to the water electrolyzer stack.

[0011] As a preferred embodiment of the present invention, the hydraulic drive assembly includes a hydraulic cylinder, a hydraulic pump, an oil tank, a two-position three-way solenoid valve, and a three-position four-way solenoid valve. The hydraulic cylinder is fixed to the lifting platform, and a pressure plate is fixed to the front end of the piston rod of the hydraulic cylinder. The pressure plate is correspondingly arranged with the upper end plate of the water electrolysis cell stack to transmit clamping force. The inlet of the hydraulic pump is connected to the oil tank, and its outlet is connected to the inlet of the two-position three-way solenoid valve. The inlet of the two-position three-way solenoid valve is also connected to an overflow valve, and the two-position three-way solenoid valve is connected to the oil tank through a return port. The outlet of the two-position three-way solenoid valve is connected to the inlet of the three-position four-way solenoid valve through a throttle valve, and the two outlets of the three-position four-way solenoid valve are respectively connected to the oil inlet and oil outlet of the hydraulic cylinder.

[0012] As a preferred embodiment of the present invention, the control unit includes a PID controller and a contact pressure controller. The PID controller calculates the required pressure value based on the changes in the contact resistance signal and the back pressure signal, sets the target pressure value in the contact pressure controller, and outputs a control signal to adjust the hydraulic system to switch between pressurization, pressure holding, or pressure reduction states. The contact pressure controller is used to detect the pressure value applied by the hydraulic system to the water electrolysis cell stack and transmit the signal to the PID controller and / or manually adjust the output pressure of the hydraulic system.

[0013] Secondly, the present invention also provides a hydraulic pressure holding control method for a high-pressure water electrolyzer stack, comprising the following steps: The contact resistance and back pressure parameters of the water electrolyzer stack are collected in real time by the sensing unit. The contact resistance parameters and back pressure parameters are transmitted to the control unit, which calculates the target pressure value based on a preset control model. The control unit controls the hydraulic system to apply a corresponding clamping force to the water electrolyzer stack according to the target pressure value, so as to maintain the effective contact pressure of the water electrolyzer stack.

[0014] As a preferred embodiment of the present invention, the pressure regulation of the hydraulic system includes a pressure boosting stage, a pressure holding stage, and a pressure reducing stage. When the contact resistance parameter increases, the system enters the pressure boosting stage, where the control unit calculates the target pressure boosting value and controls the hydraulic system to increase the clamping force to the target pressure boosting value in stages. When the contact resistance parameter stabilizes within a preset range, the system enters the pressure holding stage to maintain the current clamping force. When the back pressure parameter decreases to below a preset value, the system enters the pressure reducing stage, where the control unit calculates the target pressure reducing value and controls the hydraulic system to decrease the clamping force to the target pressure reducing value in stages.

[0015] As a preferred technical solution of the present invention, during the pressure holding stage, the continuous pressure holding of the water electrolyzer stack is achieved by closing the hydraulic oil return channel or reducing the output flow of the hydraulic pump to compensate for the natural leakage of the system.

[0016] Compared with the prior art, the beneficial effects of the present invention include: (1) The hydraulic system designed for water electrolyzers / fuel cell stacks in this invention is equipped with a replaceable centering pressure plate that can adapt to stack end plates with different surface areas. The pressure is uniformly transmitted from the center of the end plate to the surrounding area, completely solving the "edge effect" and local stress concentration problems of traditional mechanical clamping. The uniform clamping force ensures close contact between the internal components of the stack, significantly reducing contact resistance, which not only improves electrolysis efficiency but also avoids performance degradation caused by poor contact, indirectly increasing the power density of the stack.

[0017] (2) This invention utilizes PID control technology, which has a simple structure, strong robustness and high reliability. It uses the dual parameters of fuel cell contact resistance and back pressure as input factors, making it easy to implement and debug, and can accurately control the pressure. It also supports both automatic adjustment and manual operation modes. The contact pressure controller can provide real-time feedback of pressure signals and can also manually adjust the output pressure to meet the flexible adaptation needs of different test scenarios and working conditions.

[0018] (3) By designing a hydraulic pressure holding system for the high-pressure water electrolyzer stack, without making major changes to the existing hydraulic system and stack assembly, the output pressure can be automatically adjusted by the PID controller and hydraulic system. Only external conditions need to be monitored and adjusted, thereby achieving continuous high-performance operation of the water electrolyzer stack.

[0019] (4) The hydraulic pressure holding system mainly operates through processes such as pressurization, continuous pressure holding, and pressure reduction. Compared to traditional mechanical clamping devices, it can save 90%-95% of the time and significantly improve work efficiency. Moreover, the hydraulic system's overload protection function can automatically cut off the pressure source when the pressure exceeds the set value, preventing damage to the workpiece or clamp. Attached Figure Description

[0020] Figure 1This is a three-dimensional schematic diagram of a hydraulic pressure holding system for a high-pressure water electrolyzer stack according to the present invention.

[0021] Figure 2 This is a schematic diagram of the hydraulic system drive principle of the present invention.

[0022] In the diagram: 1. Electrolytic cell stack; 101. Electrolytic cell; 102. Upper end plate; 103. Lower end plate; 104. Support screw; 105. Nut; 2. Hydraulic system; 201. Chassis; 202. Column; 203. Lifting platform; 204. Hydraulic cylinder; 205. Oil inlet; 206. Oil outlet; 207. Pressure plate; 208. Hydraulic pump; 209. Oil tank; 210. Two-position three-way solenoid valve; 211. Three-position four-way solenoid valve; 212. Throttle valve; 213. Oil return port; 214. Relief valve; 3. Back pressure sensor; 4. Contact resistance sensor; 5. Tab; 6. PID controller; 7. Contact pressure controller; 8. Electromagnetic joystick. Detailed Implementation

[0023] To make the technical solution, objectives, and advantages of the present invention clearer, the high-pressure water electrolyzer stack hydraulic pressure holding system and control method of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and do not constitute a limitation thereof; the accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of protection of this patent. Some components may be omitted, enlarged, or reduced in the accompanying drawings, and their proportions do not represent the actual product dimensions; for those skilled in the art, the omission of some well-known structures and descriptions in the accompanying drawings is understandable, and the positional relationships described in the accompanying drawings are for illustrative purposes only and do not constitute a limitation thereof.

[0024] The core advantage of the fuel cell stack hydraulic pressure holding system lies in its ability to provide a powerful and stable clamping force. This uniform pressure generated by the hydraulic press ensures that the internal components of the fuel cell stack (such as membrane electrode assemblies and bipolar plates) maintain precise alignment and close contact during assembly and operation, thereby significantly reducing contact resistance, improving reaction efficiency, and effectively preventing media leakage. Through the coordinated operation of hydraulic pumps and precision control valves, based on PID control, the system can achieve stepless smooth adjustment of clamping force and long-term stable pressure holding. Its built-in overload protection mechanism can also automatically unload in case of abnormal pressure, providing reliable safety for expensive core components of the fuel cell stack. It is suitable for fuel cell or water electrolyzer test benches that have extremely high requirements for pressure control accuracy and long-term operational stability.

[0025] Example 1 like Figure 1 and Figure 2As shown, this embodiment relates to a high-pressure water electrolyzer stack hydraulic pressure holding system, which includes a water electrolyzer stack 1, a hydraulic system 2, a sensing unit, and a control unit.

[0026] The water electrolyzer stack 1 includes an electrolyzer 101, an upper end plate 102, a lower end plate 103, and supporting screws 104. The bottom end of the supporting screw 104 is fixedly connected to the lower end plate 103, and its top end extends upward through the upper end plate 102 and is fitted with a nut 105. The distance between the upper end plate 102 and the lower end plate 103 can be changed by adjusting the nut 105. Multiple supporting screws 104 are distributed along the side of the end plates, and the upper end plate 102 and the lower end plate 103 are connected by the supporting screws 104 and the nuts 105 to clamp the electrolyzer 101.

[0027] The upper plate 102 is equipped with an anode inlet / outlet (oxygen side) and a cathode inlet / outlet (hydrogen side) for the entry and exit of gas and liquid during electrolysis. A high back pressure is set at the cathode outlet, while the oxygen side is maintained at a low pressure or atmospheric pressure. Hydrogen is the target product, and its storage and subsequent utilization typically require higher pressure. Applying a high back pressure directly to the cathode side can significantly reduce or even eliminate the downstream compression stage, saving energy and reducing costs for the system.

[0028] The sensing unit includes a back pressure sensor 3 and a contact resistance sensor 4. The back pressure sensor 3 is adapted to the cathode outlet to collect the back pressure signal at the cathode outlet and feeds back the back pressure value to the control unit in real time. The contact resistance sensor 4 is electrically connected to the current collector of the electrolyzer 101 via tab 5, and is used to collect the contact resistance signal of the water electrolyzer stack 1 and transmit it to the control unit. These two signals are important references for the control unit to adjust the output pressure of the hydraulic system 2. The measurement of contact resistance is crucial for maintaining the performance of the stack. In the experiment, the four-wire method (Kelvin connection method) was used to measure the stack contact resistance, which is the most commonly used and accurate measurement method. It uses two leads to inject current into the contact resistance measuring tab 5, and the other two leads measure the voltage drop as close as possible to the connection to be tested. This method effectively eliminates the influence of the resistance of the test leads themselves and the contact resistance, thereby obtaining a more accurate sample body resistance value.

[0029] Hydraulic system 2 includes structural components and hydraulic drive components. The structural components include a chassis 201, a column 202 fixed to the chassis 201, and a lifting platform 203 mounted on the column 202. The water electrolyzer stack 1 is mounted on the chassis 201, and proper alignment is required during installation. The structural components are used to install and secure all components, withstand all pressure generated during operation, and ensure precise guidance of moving parts. The hydraulic drive components apply an adjustable clamping force to the water electrolyzer stack 1, ensuring tight contact between all components inside the stack and reducing contact resistance. When hydraulic system 2 is operating, the lifting platform 203 descends, bringing the pressure plate 207 into direct contact with the upper end plate 102. The pressure plate 207 is centered on the upper end plate 102 to distribute pressure evenly from the center to the surrounding area.

[0030] The hydraulic drive assembly comprises a hydraulic cylinder 204, a hydraulic pump 208, an oil tank 209, a two-position three-way solenoid valve 210, and a three-position four-way solenoid valve 211. The hydraulic cylinder 204 is fixed to the lifting platform 203. A pressure plate 207 is fixed to the front end of the piston rod of the hydraulic cylinder 204. The pressure plate 207 is correspondingly positioned with the upper end plate 102 of the water electrolysis cell stack 1 and is used to transmit clamping force. The inlet of the hydraulic pump 208 is connected to the oil tank 209, and its outlet is connected to the inlet of the two-position three-way solenoid valve 210. An overflow valve 214 is also connected to the inlet of the two-position three-way solenoid valve 210 to control the system's maximum pressure and also to provide safety overflow. The two-position three-way solenoid valve 210 is connected to the oil tank 209 through the return port 213, forming a circuit. The outlet of the two-position three-way solenoid valve 210 is connected to the inlet of the three-position four-way solenoid valve 211 via a throttle valve 212. The throttle valve 212 controls the flow rate of hydraulic oil, thereby controlling the rate of pressure change. The two outlets of the three-position four-way solenoid valve 211 are respectively connected to the oil inlet 205 and oil outlet 206 of the hydraulic cylinder 204, and are used to control the extension and retraction of the hydraulic cylinder 204. This hydraulic drive assembly has few components and a simple structure.

[0031] Furthermore, the pressure plate 207, which is in direct contact with the upper end plate 102 of the fuel cell stack, is removable and replaceable, and is made of insulating material. Since the fuel cell stack operates at relatively high temperatures, to avoid affecting the pressure plate 207, a material with good heat dissipation should be selected; for example, the pressure plate 207 can be coated with a ceramic matrix composite material.

[0032] The control unit includes a PID controller 6 and a contact pressure controller 7. The PID controller 6 calculates the required pressure value based on changes in the contact resistance and back pressure signals, and sets the target pressure value in the contact pressure controller 7. Simultaneously, the PID controller 6 outputs a control signal to regulate the hydraulic system 2, switching between pressurization, pressure holding, and pressure reduction states to achieve precise control of the clamping force of the water electrolyzer stack 1. The contact pressure controller 7 detects the pressure applied to the water electrolyzer stack 1 by the hydraulic system 2 and transmits the signal to the PID controller 6, forming a closed-loop control. The contact pressure controller 7 can also manually adjust the output pressure of the hydraulic system 2 to meet operational requirements under different working conditions.

[0033] During system operation, the sensing unit collects the contact resistance and back pressure signals of the water electrolyzer stack 1 in real time. The control unit calculates and adjusts the output pressure of the hydraulic system 2 based on these signals. When the contact resistance is too high, the control unit instructs the hydraulic system 2 to increase the clamping force; when the back pressure is too high, the control unit appropriately reduces the clamping force to prevent excessive internal pressure in the stack from causing seal failure or component damage. Through this real-time adjustment mechanism, the system can maintain the effective contact pressure of the water electrolyzer stack 1, ensuring electrolysis efficiency and system safety.

[0034] This high-pressure water electrolyzer stack hydraulic pressure holding system effectively reduces the contact resistance inside the stack and improves electrolysis efficiency by precisely controlling the clamping force. Simultaneously, the system can automatically adjust the clamping force according to changes in back pressure, avoiding safety hazards caused by excessive tightness or looseness and extending the equipment's service life.

[0035] Example 2 Based on a general inventive concept, this embodiment provides a hydraulic pressure holding control method for a high-pressure water electrolyzer stack. This method achieves optimized control of the stack performance by precisely controlling the clamping force applied by the hydraulic system 2 to the water electrolyzer stack 1. The method includes the following steps: Before applying pressure, ensure the fuel cell stack is precisely positioned. Place the assembled fuel cell stack on the chassis 201, ensuring the upper end plate 102 of the stack is precisely aligned with the pressure plate 207. Check the oil level in the hydraulic system 2's tank 209 and the pipeline connections, confirming that the sensors and other monitoring devices are functioning correctly. After clamping, immediately perform a leak test to determine if the seal is satisfactory.

[0036] The contact resistance and back pressure parameters of the water electrolyzer stack 1 are collected in real time by a sensing unit. The sensing unit includes a resistance sensor and a back pressure sensor 3 installed at key locations in the water electrolyzer stack 1. The resistance sensor adopts a four-wire measurement method to monitor the contact resistance changes of each cell inside the stack in real time, with a sampling frequency of 10Hz. The back pressure sensor 3 is installed on the pipeline at the cathode outlet of the stack to monitor the back pressure value inside the stack in real time, with an accuracy of ±0.1MPa.

[0037] The contact resistance and back pressure parameters are transmitted to the control unit, which calculates the target pressure value based on a preset control model. The control unit employs a PID control algorithm combined with fuzzy logic control. Based on the received contact resistance and back pressure parameters, and referring to a pre-established fuel cell stack performance model, it calculates the optimal target pressure value under the current operating conditions. This control model is based on extensive experimental data and considers the influence of multiple factors, such as fuel cell stack temperature, current density, and operating time, on the contact resistance.

[0038] The control unit controls the hydraulic system 2 to apply a corresponding clamping force to the water electrolyzer stack 1 based on the target pressure value, in order to maintain the effective contact pressure of the water electrolyzer stack 1. The hydraulic system 2 achieves precise adjustment of the stack clamping force by accurately controlling the flow and pressure of the hydraulic oil. The response time of the hydraulic system 2 is less than 200ms, and the pressure control accuracy reaches ±0.5%.

[0039] The pressure regulation of hydraulic system 2 includes a pressure boosting stage, a pressure holding stage, and a pressure reduction stage, which are implemented as follows: When the contact resistance parameter rises, the pressurization stage begins. The control unit detects that the fuel cell stack contact resistance parameter has risen above a preset threshold and immediately initiates the pressurization program. Based on the rate and magnitude of the contact resistance increase, combined with the fuel cell stack's operating state, the control unit calculates the target pressurization value and sets it in the contact pressure controller 7. The pressurization process employs a phased strategy: the hydraulic pump 208 draws oil from the oil tank 209, the PID controller transmits a control signal to the electromagnetic lever 8, which controls the solenoid valve to the right position, opening the drain valve in one direction, and lowering the pressure plate 207 to apply pressure in stages (e.g., 30%, 50%, 80% of the total target) until the predetermined value is reached, preventing pressure overshoot that could damage the fuel cell stack. During the pressurization process, the contact pressure controller 7 continuously monitors pressure changes; once the target pressurization value is reached, pressurization stops and the system enters the pressure holding stage.

[0040] When the contact resistance parameter stabilizes within the preset range, the pressure holding stage begins. During this stage, the current clamping force remains constant, and continuous pressure holding of the water electrolysis cell stack 1 is achieved by closing the hydraulic oil return channel or reducing the output flow of the hydraulic pump 208 to the leakage compensation flow. Specifically, the PID controller issues a command to control the three-position four-way solenoid valve 211 to the neutral position via the electromagnetic lever 8, forming a closed loop to prevent hydraulic oil backflow; or the output flow of the hydraulic pump 208 is adjusted to the minimum value that can only compensate for the system's natural leakage, maintaining a constant system pressure. This method is more suitable for applications with longer pressure holding times and higher system efficiency requirements. During the pressure holding stage, the contact resistance and back pressure parameters are continuously monitored, and if any significant change occurs, the corresponding pressure adjustment stage is immediately initiated.

[0041] When the back pressure parameter decreases below the preset value, the decompression stage begins. The control unit detects the decrease in back pressure, calculates the target decompression value, and sets the target decompression value in the contact pressure controller 7. The control system 2 then reduces the clamping force in stages to the target decompression value. The decompression process also employs a staged strategy. The PID controller transmits control signals to the electromagnetic lever 8, which controls the solenoid valve to the left position, opens the suction valve in one direction, and moves the pressure plate 207 upward, gradually reducing the pressure to the predetermined value (e.g., 80%, 50%, 30% of the total target) to ensure the fuel cell stack sealing performance is not affected. During the decompression process, changes in the back pressure parameter are continuously monitored. Once the back pressure begins to rise and reaches the preset safety value, the decompression is stopped, and the system status is reassessed.

[0042] The above method enables intelligent control of hydraulic pressure holding of the water electrolyzer stack 1, effectively extending the stack's service life, improving electrolysis efficiency, reducing energy consumption, and ensuring that the stack maintains optimal contact pressure under various operating conditions.

[0043] Based on the description and accompanying drawings of this invention, those skilled in the art can easily manufacture or use the high-pressure water electrolyzer stack hydraulic pressure holding system and control method of this invention, and can produce the positive effects described in this invention.

[0044] Unless otherwise specified, in this invention, terms such as "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" 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 this invention and 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, the terms used to describe orientation or positional relationships in this invention are for illustrative purposes only and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood in conjunction with the accompanying drawings and according to the specific circumstances.

[0045] Unless otherwise explicitly specified and limited, the terms "set up," "connected," and "linked" in this invention should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A hydraulic pressure-maintaining system for a high-pressure water electrolyzer stack, characterized in that, include: Water electrolyzer stack (1); A hydraulic system (2) is used to apply an adjustable clamping force to the water electrolyzer stack (1); The sensing unit is used to collect the contact resistance signal and back pressure signal of the water electrolysis cell stack (1) in real time; The control unit is electrically connected to the hydraulic system (2) and the sensing unit respectively. The control unit receives the contact resistance signal and the back pressure signal and is used to adjust the output pressure of the hydraulic system (2) to maintain the effective contact pressure of the water electrolysis cell stack (1).

2. The high-pressure water electrolyzer stack hydraulic pressure holding system according to claim 1, characterized in that, The water electrolysis cell stack (1) includes an electrolysis cell (101), an upper end plate (102), a lower end plate (103), and a support screw (104). The bottom end of the support screw (104) is fixedly connected to the lower end plate (103), and its top end extends upward through the upper end plate (102) and is equipped with a nut (105). The distance between the upper end plate (102) and the lower end plate (103) is adjustable.

3. The high-pressure water electrolyzer stack hydraulic pressure holding system according to claim 2, characterized in that, The back pressure signal is acquired from the back pressure of the cathode outlet of the upper end plate (102). The sensing unit includes a back pressure sensor (3) adapted to the cathode outlet. The back pressure sensor (3) is used to display and feed back the back pressure value to the control unit.

4. The high-pressure water electrolyzer stack hydraulic pressure holding system according to claim 3, characterized in that, The sensing unit also includes a contact resistance sensor (4), which is electrically connected to the current collector of the electrolytic cell (101) via a tab (5) to collect the contact resistance signal of the water electrolytic cell stack (1) and transmit it to the control unit.

5. The high-pressure water electrolyzer stack hydraulic pressure holding system according to claim 1, characterized in that, The hydraulic system (2) includes a structural component and a hydraulic drive component. The structural component includes a chassis (201), a column (202) fixed on the chassis (201), and a lifting platform (203) set on the column (202). The water electrolyzer stack (1) is placed on the chassis (201). The hydraulic drive component is used to apply an adjustable clamping force to the water electrolyzer stack (1).

6. The high-pressure water electrolyzer stack hydraulic pressure holding system according to claim 5, characterized in that, The hydraulic drive assembly includes a hydraulic cylinder (204), a hydraulic pump (208), an oil tank (209), a two-position three-way solenoid valve (210), and a three-position four-way solenoid valve (211). The hydraulic cylinder (204) is fixed on the lifting platform (203). A pressure plate (207) is fixed to the front end of the piston rod of the hydraulic cylinder (204). The pressure plate (207) is correspondingly arranged with the upper end plate (102) of the water electrolysis cell stack (1) to transmit clamping force. The inlet of the hydraulic pump (208) is connected to the oil tank (209), and its outlet is connected to the... The inlet of the two-position three-way solenoid valve (210) is connected; the inlet of the two-position three-way solenoid valve (210) is also connected to an overflow valve (214); the two-position three-way solenoid valve (210) is connected to the oil tank (209) through the return port (213); the outlet of the two-position three-way solenoid valve (210) is connected to the inlet of the three-position four-way solenoid valve (211) through a throttle valve (212); the two outlets of the three-position four-way solenoid valve (211) are respectively connected to the oil inlet (205) and oil outlet (206) of the hydraulic cylinder (204).

7. The high-pressure water electrolyzer stack hydraulic pressure holding system according to claim 1, characterized in that, The control unit includes a PID controller (6) and a contact pressure controller (7). The PID controller (6) calculates the required pressure value based on the changes in the contact resistance signal and the back pressure signal, sets the target pressure value in the contact pressure controller (7), and outputs a control signal to adjust the hydraulic system (2) to switch between pressurization, pressure holding, or pressure reduction states. The contact pressure controller (7) is used to detect the pressure value applied by the hydraulic system (2) to the water electrolysis cell stack (1) and transmit the signal to the PID controller (6) and / or manually adjust the output pressure of the hydraulic system (2).

8. A method for hydraulic pressure holding control of a high-pressure water electrolyzer stack, characterized in that, Includes the following steps: The contact resistance parameters and back pressure parameters of the water electrolyzer stack (1) are collected in real time by the sensing unit. The contact resistance parameters and back pressure parameters are transmitted to the control unit, which calculates the target pressure value based on a preset control model. The control unit controls the hydraulic system (2) to apply a corresponding clamping force to the water electrolyzer stack (1) according to the target pressure value, so as to maintain the effective contact pressure of the water electrolyzer stack (1).

9. The hydraulic pressure holding control method for the high-pressure water electrolyzer stack according to claim 8, characterized in that, The pressure regulation of the hydraulic system (2) includes a pressure boosting stage, a pressure holding stage, and a pressure reduction stage. When the contact resistance parameter rises, the system enters the pressure boosting stage. The control unit calculates the target pressure boosting value and controls the hydraulic system (2) to increase the clamping force to the target pressure boosting value in stages. When the contact resistance parameter stabilizes within a preset range, the system enters the pressure holding stage to maintain the current clamping force. When the back pressure parameter decreases to below the preset value, the system enters the pressure reduction stage. The control unit calculates the target pressure reduction value and controls the hydraulic system (2) to decrease the clamping force to the target pressure reduction value in stages.

10. The hydraulic pressure holding control method for the high-pressure water electrolyzer stack according to claim 9, characterized in that, During the pressure holding stage, the water electrolysis cell stack (1) is kept under continuous pressure by closing the hydraulic oil return channel or reducing the output flow of the hydraulic pump (208) to compensate for the natural leakage of the system.

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