Variable speed and variable displacement control method and device for inhibiting hydrogen compressor reversing impact

Abstract

The application provides a variable-speed variable-displacement control method and device for inhibiting reversing impact of a liquid-driven hydrogen compressor, and relates to the field of reversing of a liquid-driven hydrogen compressor. The method comprises the following steps: S1, cosine trajectory planning is adopted to obtain a variable-load forward trajectory equation and a variable-load return trajectory equation; S2, differential operation is adopted to obtain the speed and acceleration of two working conditions; S3, the total efficiency of the liquid-driven hydrogen compressor is constructed according to the loss of each core link of the liquid-driven hydrogen compressor, and the dynamic response time is combined to finally obtain an optimization evaluation coefficient; S4, a particle swarm algorithm is adopted to obtain an optimal parameter combination; and S5, based on the optimal parameter combination, the speed of a servo motor and the displacement of a bidirectional variable pump are adjusted to make the motion trajectory fit the planning trajectory. The application solves the technical problems of high piston impact speed, large inertial force and large fluid pressure coupling impact peak value in the reversing process of the existing liquid-driven hydrogen compressor, and effectively inhibits the reversing impact and significantly reduces the vibration level of the whole machine.

Description

Technical Field

[0001] This invention relates to the field of commutation of liquid-driven hydrogen compressors, and more specifically to a variable speed and variable displacement control method and device for suppressing commutation shock in liquid-driven hydrogen compressors. Background Technology

[0002] Hydrogen compression is a crucial booster step in the hydrogen energy industry chain, with its core equipment often being a liquid-driven hydrogen compressor. A liquid-driven hydrogen compressor uses a hydraulic cylinder to drive a piston in reciprocating motion to change the gas volume, thereby compressing and transporting hydrogen. However, in actual operation, due to the wide-frequency transient switching of the hydraulic system and sudden changes in load pressure, the piston is prone to severe reversing shocks at the end of its stroke. Existing methods for suppressing reversing shocks in liquid-driven hydrogen compressors have the following main shortcomings: 1. Existing technologies mainly focus on passive or semi-active control methods such as adding accumulators and throttling buffer devices to the hydraulic system circuit. However, these methods have inherent defects such as limited buffering effect and response lag when facing the complex operating environment of hydrogen compressors with varying loads and operating conditions, making it difficult to actively adjust the buffering strategy according to real-time changes in operating conditions.

[0003] 2. Currently, liquid-driven hydrogen compressors generally use a control method where limit switches or proximity switches trigger the directional valve. The electro-hydraulic directional valve only responds and reverses direction after the piston reaches the end of its stroke and triggers the switch signal. Due to the inherent time delay between switch triggering and valve core movement, the piston may continue to travel a short distance due to inertia after triggering the limit switch, easily leading to piston collision. Furthermore, risks such as missing contact signals and insufficient pressure resistance of components further reduce the system's reliability.

[0004] 3. Under traditional control strategies, the piston approaches the dead center with a high initial velocity at the end of its stroke. The velocity and acceleration undergo a drastic change at the moment of reversal, resulting in a significant impact peak caused by the coupling effect of inertial force and fluid pressure. Existing methods fail to flexibly plan and actively dampen the velocity and acceleration at the piston's end from the kinematic source, and therefore cannot fundamentally reduce the reversal impact.

[0005] 4. Existing hydraulic drive systems mostly adopt an open hydraulic scheme with a fixed displacement pump and a reversing valve, or only adjust the servo motor speed as a single variable. Such schemes have an inherent contradiction between system efficiency, response speed and control accuracy - throttling losses result in considerable heat generation in high-power systems, while the single-variable control method makes it difficult to optimize system efficiency while ensuring output power and motion accuracy.

[0006] In summary, the existing liquid-driven hydrogen compressors suffer from high piston impact speed and large peak impact due to the coupling of inertial force and fluid pressure during commutation. There is an urgent need for a control method that can actively adapt to changes in operating conditions, achieve flexible deceleration at the piston end through motion trajectory planning, and collaboratively optimize the operating parameters of the power source, so as to effectively suppress the commutation impact of the liquid-driven hydrogen compressor and comprehensively improve the overall performance of the machine. Summary of the Invention

[0007] To address the shortcomings of the prior art, the present invention aims to provide a variable speed and variable displacement control method and device for suppressing the reversing impact of a liquid-driven hydrogen compressor. This method and device can achieve flexible deceleration at the piston end through motion trajectory planning and control the motion trajectory by optimizing the operating parameters of the power source, thereby effectively suppressing the reversing impact of the bidirectional variable pump and the overall vibration level of the machine.

[0008] Specifically, on the one hand, the present invention provides a variable speed and variable displacement control method for suppressing reversing shock in a liquid-driven hydrogen compressor, which includes the following steps: S1. Using cosine trajectory planning, the motion trajectory of the liquid-driven hydrogen compressor is planned to minimize the peak value of acceleration, thus obtaining the outward trajectory equation and return trajectory equation for the variable load. , ; , ; in, The equation for the outbound trajectory is... The equation for the return trajectory is... To compress time, For compressed length, For compression cycle; S2. Differential operations are used to differentiate the trajectory equation step by step to obtain the velocity and acceleration for the two working conditions; S3. Based on the speed and acceleration under two operating conditions, the overall efficiency of the liquid-driven hydrogen compressor is constructed according to the losses of each core component. The dynamic response time is then constructed based on the response efficiencies of the bidirectional variable pump and servo motor, ultimately yielding the optimization evaluation coefficients. Specifically, this includes: S31. Based on the speed and acceleration of the two working conditions, establish efficiency sub-models for each core component, and finally obtain the total efficiency of the liquid-driven hydrogen compressor through the product relationship of the efficiencies of each component. S32. Based on the displacement change rate of the bidirectional variable pump and the rotational inertia of the servo motor, construct the dynamic response time; S33. With the dual optimization objectives of maximizing the total efficiency of the liquid-driven hydrogen compressor and minimizing the dynamic response time, the total efficiency and dynamic response time of the liquid-driven hydrogen compressor are normalized, and the optimization evaluation coefficient is constructed by weighted summation. S4. Using the optimization evaluation coefficient as the fitness evaluation criterion, the particle swarm algorithm is used to perform a global search in the two-dimensional parameter space composed of the servo motor speed and the bidirectional variable pump displacement to obtain the optimal parameter combination. S5. Based on the optimal parameter combination, the piston position and speed signals are collected in real time, and the servo motor speed and bidirectional variable pump displacement are adjusted to make the motion trajectory conform to the planned trajectory.

[0009] Preferably, the speed and acceleration of the liquid-driven hydrogen compressor under both operating conditions include the outward speed. Return speed outbound acceleration and return acceleration ; , ; , ; , ; , .

[0010] Preferably, S31 includes: S311. Based on the velocity and acceleration of the two working conditions obtained in S2, calculate the displacement of the bidirectional variable pump and the system pressure difference; S312. Based on the displacement of the bidirectional variable pump and the system pressure difference, combined with the fluid dynamics lubrication theory and the law of viscous friction, a quantitative relationship between mechanical loss power and operating parameters is established to obtain the mechanical efficiency of the bidirectional variable pump. S313. Based on the displacement of the bidirectional variable pump and the system pressure difference, combined with the relationship between the pressure difference and leakage characteristics of the liquid-driven hydrogen compressor, the system pressure difference, oil dynamic viscosity, servo motor speed and bidirectional variable pump displacement are used as key influencing parameters to obtain the volumetric efficiency of the bidirectional variable pump. S314. Based on the energy balance relationship of the servo motor, calculate the input mechanical power, and after deducting mechanical friction loss, iron loss and copper loss, obtain the output mechanical power and the servo motor efficiency. S315. Based on the system pressure difference, the actual input power is represented by the product of the piston force and the movement speed, and the ideal compression power is represented by the product of the pressure and flow rate in the compression chamber, thus obtaining the hydraulic cylinder efficiency. S316. Considering that efficiency losses accumulate at each stage in the entire power chain from servo motor input to compressor cylinder output, based on the power flow series transmission characteristics, the overall efficiency of the liquid-driven hydrogen compressor is constructed. for: ; in, For the mechanical efficiency of a bidirectional variable pump, For the volumetric efficiency of a bidirectional variable pump, For servo motor efficiency, For hydraulic cylinder efficiency.

[0011] Preferably, the dynamic response time in S32 for: ; ; ; in, The first system response time, For the response time of the second system, This represents the initial steady-state displacement. The displacement corresponding to the target demand flow. This refers to the rate of change of displacement of a bidirectional variable pump. The rotational speed under initial steady state. The rotational speed corresponding to the target required flow rate. This refers to the equivalent rotational inertia of the servo motor and the pump. This represents the maximum output torque of the servo motor. This is the load torque referred to the servo motor shaft; S33 Optimization Evaluation Coefficient for: ; in, To find the optimal first weight coefficient, To find the optimal second weighting coefficient, + =1, To find the optimal first normalized reference value, To find the optimal second normalized benchmark value.

[0012] Preferably, S4 includes: S41. Based on the servo motor speed and the bidirectional variable pump displacement, a two-dimensional parameter space is constructed. S42. Based on the coupling relationship between servo motor speed and bidirectional variable pump displacement, the particle swarm algorithm is used to perform a global search in the two-dimensional parameter space to obtain the optimal parameter combination. S43. Evaluate the overall performance of the optimal parameter combination using the optimization evaluation coefficient. If the current optimal parameter combination fails to make the actual piston motion trajectory conform to the motion trajectory planned in S1 or the overall performance fails to reach the target range, continue to iterate and update the particle parameters. Specifically, the particle swarm optimization formula is as follows: ; ; in, For the first iteration For the i-th particle The particle velocity vector of the iteration step. For the i-th particle The particle velocity vector of the iteration step. For the i-th particle in the... The two-dimensional position vector of the iteration step. For the i-th particle in the... The two-dimensional position vector of the iteration step. For inertial weights, As the first learning factor, As the second learning factor, The first random number in the interval [0,1] The second random number in the interval [0,1] This represents the historical best position of the i-th particle. This is the globally optimal position for the entire population.

[0013] Preferably, the mechanical efficiency of the bidirectional variable pump is: ; in, This is the mechanical drag coefficient. The dynamic viscosity of the oil. For servo motor speed, For system pressure difference, This refers to the displacement of a bidirectional variable pump.

[0014] Preferably, the volumetric efficiency of the bidirectional variable pump is: ; in, The laminar leakage coefficient is... The dynamic viscosity of the oil. For servo motor speed, For system pressure difference, This refers to the displacement of a bidirectional variable pump.

[0015] Preferably, the servo motor efficiency is: ; in, For the servo motor output torque, For the angular velocity of the servo motor, For the mechanical losses of the servo motor, For the iron loss of the servo motor, This refers to the copper loss of the servo motor.

[0016] Preferably, the hydraulic cylinder efficiency for: ; in, For the output force of the hydraulic cylinder, For the speed of the hydraulic cylinder, For system pressure difference, Input flow rate to the hydraulic cylinder.

[0017] On the other hand, the present invention provides an apparatus for the variable speed and variable displacement control method for suppressing the reversing impact of the above-mentioned liquid-driven hydrogen compressor, comprising: a servo motor, a bidirectional variable pump, and a hydraulic cylinder; the servo motor is connected to the bidirectional variable pump via a coupling, and the two oil outlets of the bidirectional variable pump are respectively connected to the two oil inlets of the hydraulic cylinder, driving the piston of the hydraulic cylinder to reciprocate, and the piston drives the compression chamber to complete the hydrogen compression; the hydraulic cylinder is equipped with a displacement sensor and a speed sensor to detect the displacement and movement speed of the hydraulic cylinder piston in real time; a first pressure sensor and a second pressure sensor are respectively installed at the connection between the bidirectional variable pump and the hydraulic cylinder to detect the system pressure in real time; the displacement sensor, speed sensor, first pressure sensor and second pressure sensor convert the collected data into electrical signals and feed them back to the controller, the controller outputs a control signal to the driver according to the electrical signal, the driver drives the servo motor to adjust the speed, and at the same time the controller directly controls the displacement of the bidirectional variable pump to realize closed-loop control; A hot oil shuttle valve is also installed between the bidirectional variable pump and the hydraulic cylinder. The outlet of the hot oil shuttle valve is connected to the third relief valve, which is connected to the water-cooled oil inlet of the servo motor. The water-cooled oil outlet of the servo motor is connected to the cooler, together forming a heat exchange circuit. The high-temperature hot oil of the system is introduced into the cooling channel of the servo motor and then returned to the accumulator to realize thermal management.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Based on the power architecture of a servo motor-driven bidirectional variable pump, this invention actively plans the entire compression process of a liquid-driven hydrogen compressor, employing a cosine trajectory to achieve a smooth transition between piston speed and acceleration, thus establishing a flexible flow transition mechanism. This active planning strategy allows for pre-setting the end-effector trajectory according to changes in operating conditions, significantly reducing hydraulic pipeline pressure pulsation, effectively suppressing reversing shocks, and extending the fatigue life of hydraulic components and mechanical transmission parts.

[0019] 2. This invention uses closed-loop feedback to collect piston displacement and speed data in real time, enabling dynamic adjustment of the servo motor speed and bidirectional variable pump displacement to adapt to different load conditions. By continuously correcting the actual piston trajectory to the planned curve, the risk of cylinder collision caused by switching signal delay is eliminated, achieving precise control and flexible decay of the piston stroke at the end, significantly improving system reliability and operational safety.

[0020] 3. This invention pre-designs a cosine deceleration trajectory at the end of the stroke, ensuring that the piston's velocity and acceleration smoothly transition to zero continuously according to a cosine law as it approaches the dead center, thus avoiding abrupt changes in velocity and acceleration. Through this flexible attenuation mechanism, this invention fundamentally reduces the impact peak caused by the coupling of inertial force and fluid pressure, achieving active suppression of reversing impacts in liquid-driven hydrogen compressors.

[0021] 4. This invention constructs a comprehensive evaluation function and utilizes a particle swarm optimization algorithm to perform a global bivariate search on the target speed of the servo motor and the target displacement of the bidirectional variable pump to determine the optimal power coupling parameters under different load conditions. The combination of speed and displacement obtained through this method can ensure that the servo motor and pump system always operate in the high-efficiency range while maintaining output power and motion accuracy. This significantly reduces system power loss and heat generation, achieving a dual improvement in overall energy efficiency and dynamic control accuracy. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the variable speed and variable displacement control method for suppressing reversing impact in a liquid-driven hydrogen compressor according to the present invention. Figure 2 This is a schematic diagram of the device structure of the present invention; Figure 3 This is a schematic diagram of the motion trajectory control method of the present invention; Figure 4 This is a diagram of the planned trajectory displacement curve of the present invention; Figure 5 This is a diagram of the planned trajectory velocity curve of the present invention; Figure 6 This is a graph showing the acceleration curve of the planned trajectory in this invention.

[0023] Key reference numerals in the attached drawings: 1. Servo motor; 2. Coupling; 3. Bidirectional variable pump; 41. First check valve; 42. Second check valve; 51. First relief valve; 52. Second relief valve; 6. Hot oil shuttle valve; 7. Third relief valve; 81. First pressure sensor; 82. Second pressure sensor; 9. Hydraulic cylinder; 10. Cooler; 11. Accumulator; 12. Displacement sensor; 13. Speed ​​sensor; 14. Controller; 15. Driver. Detailed Implementation

[0024] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0025] This invention provides a variable speed and variable displacement control method for suppressing commutation shock in a liquid-driven hydrogen compressor, such as... Figure 1 and Figure 3 As shown, it includes the following steps: S1. Cosine trajectory planning is used to plan the motion trajectory of the liquid-driven hydrogen compressor, ensuring minimal impact while minimizing peak acceleration and making the acceleration smoother, thus obtaining the outward trajectory equation for the variable load. Equation of return trajectory : , ; , ; in, To compress time, For compressed length, This is the compression cycle.

[0026] Specifically, the compression length is determined by the length of the compression cylinder of different hydrogen compressors, and the compression cycle is the preset required single compression time.

[0027] In a preferred embodiment, the planned trajectory displacement curve is shown below. Figure 4 As shown, the acceleration curve of the planned trajectory is as follows: Figure 6 As shown.

[0028] S2. Differential operations are used to differentiate the trajectory equation obtained in S1 step by step to obtain the velocity and acceleration of the liquid-driven hydrogen compressor under two operating conditions.

[0029] Specifically, the speed and acceleration of the liquid-driven hydrogen compressor under two operating conditions include the outward speed. Return speed outbound acceleration and return acceleration .

[0030] , ; , ; , ; , ; In a preferred embodiment, the planned trajectory velocity curve is as follows: Figure 5 As shown.

[0031] S3. Based on the speed and acceleration obtained in S2 for the two working conditions, the total efficiency of the liquid-driven hydrogen compressor is constructed according to the losses of each core component of the liquid-driven hydrogen compressor, and the dynamic response time is constructed based on the response efficiencies of the bidirectional variable pump and servo motor, and finally the optimization evaluation coefficient is obtained.

[0032] S31. Based on the speed and acceleration of the two working conditions obtained in S2, the power flow topology analysis method is used to track the energy flow and loss characteristics step by step along the power transmission link, establish the efficiency sub-model of each core link, and finally obtain the total efficiency of the liquid-driven hydrogen compressor through the product relationship of the efficiencies of each link.

[0033] S311. Based on the velocity and acceleration of the two working conditions obtained in S2, calculate the displacement of the bidirectional variable pump and the system pressure difference; ; in, For the bidirectional variable pump displacement, A is the effective compression area inside the hydraulic cylinder, va is the piston speed, and n is the motor speed.

[0034] ; in, For system pressure difference, Let A be the piston acceleration, A be the effective compression area inside the hydraulic cylinder, and m be the total equivalent mass of the moving parts.

[0035] S312. Based on the displacement of the bidirectional variable pump and the system pressure difference, combined with fluid dynamics lubrication theory and the law of viscous friction, a quantitative relationship between mechanical loss power and operating parameters is established to obtain the mechanical efficiency of the bidirectional variable pump. for: ; in, This is the mechanical drag coefficient. The dynamic viscosity of the oil. For servo motor speed, For system pressure difference, This refers to the displacement of a bidirectional variable pump.

[0036] S313. Based on the displacement of the bidirectional variable pump and the system pressure difference, combined with the relationship between the pressure difference and leakage characteristics of the liquid-driven hydrogen compressor, and taking the system pressure difference, oil dynamic viscosity, servo motor speed, and bidirectional variable pump displacement as key influencing parameters, the volumetric efficiency of the bidirectional variable pump is obtained. for: ; in, This is the laminar leakage coefficient.

[0037] S314. Considering the power loss during the conversion of electrical energy to mechanical energy in a servo motor, based on the energy balance relationship of the servo motor, the input mechanical power is represented by the product of electromagnetic torque and speed. After deducting mechanical friction loss, iron loss, and copper loss, the output mechanical power is obtained, thus yielding the servo motor efficiency. for: ; in, For the servo motor output torque, For the angular velocity of the servo motor, For the mechanical losses of the servo motor, For the iron loss of the servo motor, This refers to the copper loss of the servo motor.

[0038] S315. Based on the system pressure difference, and considering that the actual compression process of hydrogen in the compression chamber is non-isothermal, resulting in the actual hydraulic energy consumed being higher than the theoretical compression work, the actual input power is represented by the product of the piston force and the movement speed, and the ideal compression power is represented by the product of the pressure and the flow rate in the compression chamber, thus obtaining the hydraulic cylinder efficiency. for: ; in, For the output force of the hydraulic cylinder, For the speed of the hydraulic cylinder, Input flow rate to the hydraulic cylinder.

[0039] S316. Considering that efficiency losses accumulate at each stage in the entire power chain from servo motor input to compressor cylinder output, based on the power flow series transmission characteristics, the overall efficiency of the liquid-driven hydrogen compressor is constructed. for: .

[0040] S32. Based on the rate of change of displacement of the bidirectional variable pump and the moment of inertia of the servo motor, construct a dynamic response time that can characterize the relationship between the time of displacement change of the bidirectional variable pump and the speed of the servo motor. for: ; ; ; in, The first system response time, For the response time of the second system, This represents the initial steady-state displacement. The displacement corresponding to the target demand flow. This refers to the rate of change of displacement of a bidirectional variable pump. The rotational speed under initial steady state. The rotational speed corresponding to the target required flow rate. This refers to the equivalent rotational inertia of the servo motor and the pump. This represents the maximum output torque of the servo motor. This is the load torque referred to the servo motor shaft.

[0041] S33. With the dual optimization objectives of maximizing the total efficiency of the liquid-driven hydrogen compressor and minimizing the dynamic response time, the total efficiency of the liquid-driven hydrogen compressor obtained in S31 and the dynamic response time obtained in S32 are normalized, and an optimization evaluation is constructed by weighted summation. for: ; in, To find the optimal first weight coefficient, To find the optimal second weighting coefficient, + =1, To find the optimal first normalized reference value, To find the optimal second normalized benchmark value.

[0042] Specifically, the larger the optimization evaluation coefficient value, the better the system performance, the higher the efficiency, and the faster the response under the current combination of speed and displacement.

[0043] S4. Using the optimization evaluation coefficients constructed in S33 as fitness evaluation criteria, the particle swarm algorithm is used to perform a global search in the two-dimensional parameter space composed of the servo motor speed and the bidirectional variable pump displacement to obtain the parameter combination that optimizes the overall performance of the system.

[0044] S41. Based on the servo motor speed and the bidirectional variable pump displacement, a two-dimensional parameter space is constructed.

[0045] ; ; in, For the j-th parameter combination in the two-dimensional parameter space, Let j be the servo motor speed for the j-th parameter combination. For the j-th parameter combination, the displacement of the bidirectional variable pump is... Let j be the iteration step size of the j-th parameter combination. The iteration step size of the j-th parameter combination in the motor speed dimension. The iteration step size of the j-th parameter combination in the bidirectional variable pump displacement dimension, where Tβ is the transpose vector.

[0046] S42. Based on the coupling relationship between servo motor speed and bidirectional variable pump displacement, a particle swarm optimization algorithm is used to perform a global search in the two-dimensional parameter space to obtain the optimal parameter combination.

[0047] Specifically, the particle swarm optimization algorithm formula is as follows: ; ; in, For the first iteration For the i-th particle The particle velocity vector of the iteration step. For the i-th particle The particle velocity vector of the iteration step. For the i-th particle in the... The two-dimensional position vector of the iteration step. For the i-th particle in the... The two-dimensional position vector of the iteration step. For inertial weights, As the first learning factor, As the second learning factor, The first random number in the interval [0,1] The second random number in the interval [0,1] This represents the historical best position of the i-th particle. This is the globally optimal position for the entire population.

[0048] S43. The optimization evaluation coefficient constructed by S33 is used to evaluate the comprehensive performance of the optimal parameter combination. If the current optimal parameter combination fails to make the actual piston motion trajectory conform to the motion trajectory planned by S1 or the comprehensive performance fails to reach the target range, the particle parameters are iteratively updated.

[0049] S5. Based on the optimal parameter combination obtained from S4, and combined with the displacement sensor and speed sensor inside the compression chamber to collect piston position and speed signals in real time, adjust the servo motor speed and bidirectional variable pump displacement to make the motion trajectory conform to the planned trajectory.

[0050] On the other hand, the present invention provides an apparatus for a variable speed and variable displacement control method to suppress commutation shock in a liquid-driven hydrogen compressor, such as... Figure 2 As shown, the core components include: servo motor 1, coupling 2, bidirectional variable pump 3, first check valve 41, second check valve 42, first relief valve 51, second relief valve 52, third relief valve 7, first pressure sensor 81, second pressure sensor 82, hot oil shuttle valve 6, hydraulic cylinder 9, cooler 10, accumulator 11, displacement sensor 12, speed sensor 13, controller 14, and driver 15.

[0051] Specifically, the connection relationships of the core components of the suppressor liquid-driven hydrogen compressor are as follows: Servo motor 1 is connected to bidirectional variable pump 3 via coupling 2, serving as a power source to provide the required pressure and flow to the system. The two outlets of bidirectional variable pump 3 are connected to the two inlets of hydraulic cylinder 9, driving the piston of hydraulic cylinder 9 to reciprocate. The piston drives the compression chamber to compress hydrogen. Hydraulic cylinder 9 is equipped with displacement sensor 12 and speed sensor 13 to detect the displacement and speed of the piston in real time. A first pressure sensor 81 and a second pressure sensor 82 are respectively installed at the connection between bidirectional variable pump 3 and hydraulic cylinder 9 to detect the system pressure in real time. Displacement sensor 12, speed sensor 13, first pressure sensor 81, and second pressure sensor 82 convert the collected data into electrical signals and feed them back to controller 14. Controller 14 outputs control signals to driver 15 based on the electrical signals. Driver 15 drives servo motor 1 to adjust its speed, while controller 14 directly regulates the displacement of bidirectional variable pump 3, achieving closed-loop control.

[0052] The bidirectional variable pump 3 is connected to the accumulator 11 through the leakage oil circuit L1. The oil port of the accumulator 11 is connected to the first overflow valve 51 and the second overflow valve 52 respectively. The three together form a system safety overflow module to overflow to the accumulator 11 to stabilize the pressure when the pressure exceeds the limit. The accumulator 11 cooperates with the first check valve 41 and the second check valve 42 to automatically replenish oil when the system oil is missing.

[0053] A hot oil shuttle valve 6 is also provided between the bidirectional variable pump 3 and the hydraulic cylinder 9. The oil outlet of the hot oil shuttle valve 6 is connected to the third relief valve 7. The third relief valve 7 is connected to the water-cooled oil inlet L2 of the servo motor 1. The water-cooled oil outlet L3 of the servo motor 1 is connected to the cooler 10. Together, they form a heat exchange circuit, which introduces the high-temperature hot oil of the system into the cooling channel of the servo motor 1 and then returns it to the accumulator 11 to achieve thermal management.

[0054] Specifically, the two main oil circuits between the bidirectional variable pump 3 and the hydraulic cylinder 9 are respectively led out to the two oil inlets of the shuttle valve 6, and the third relief valve 7 is connected to the oil outlet of the hot oil shuttle valve 6.

[0055] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A variable speed and variable displacement control method for suppressing commutation shock in a liquid-driven hydrogen compressor, characterized in that the steps include... include: S1. Using cosine trajectory planning, the motion trajectory of the liquid-driven hydrogen compressor is planned to minimize the peak value of acceleration, thus obtaining the outward trajectory equation and return trajectory equation for the variable load. ， ； ， ； in, The equation for the outbound trajectory is... The equation for the return trajectory is... To compress time, For compressed length, For compression cycle; S2. Differential operations are used to differentiate the trajectory equation step by step to obtain the velocity and acceleration for the two working conditions; S3. Based on the speed and acceleration under two operating conditions, the overall efficiency of the liquid-driven hydrogen compressor is constructed according to the losses of each core component. The dynamic response time is then constructed based on the response efficiencies of the bidirectional variable pump and servo motor, ultimately yielding the optimization evaluation coefficients. Specifically, this includes: S31. Based on the speed and acceleration of the two working conditions, establish efficiency sub-models for each core component, and finally obtain the total efficiency of the liquid-driven hydrogen compressor through the product relationship of the efficiencies of each component. S32. Based on the displacement change rate of the bidirectional variable pump and the rotational inertia of the servo motor, construct the dynamic response time; S33. With the dual optimization objectives of maximizing the total efficiency of the liquid-driven hydrogen compressor and minimizing the dynamic response time, the total efficiency and dynamic response time of the liquid-driven hydrogen compressor are normalized, and the optimization evaluation coefficient is constructed by weighted summation. S4. Using the optimization evaluation coefficient as the fitness evaluation criterion, the particle swarm algorithm is used to perform a global search in the two-dimensional parameter space composed of the servo motor speed and the bidirectional variable pump displacement to obtain the optimal parameter combination. S5. Based on the optimal parameter combination, the piston position and speed signals are collected in real time, and the servo motor speed and bidirectional variable pump displacement are adjusted to make the motion trajectory conform to the planned trajectory.

2. The variable speed and variable displacement control method for suppressing reversing impact in a liquid-driven hydrogen compressor according to claim 1, characterized in that, Speed ​​and acceleration of the liquid-driven hydrogen compressor under two operating conditions, including outward speed Return speed outbound acceleration and return acceleration ; ， ； ， ； ， ； ， 。 3. The variable speed and variable displacement control method for suppressing reversing impact in a liquid-driven hydrogen compressor according to claim 1, characterized in that, S31 includes: S311. Based on the velocity and acceleration of the two working conditions obtained in S2, calculate the displacement of the bidirectional variable pump and the system pressure difference; S312. Based on the displacement of the bidirectional variable pump and the system pressure difference, combined with the fluid dynamics lubrication theory and the law of viscous friction, a quantitative relationship between mechanical loss power and operating parameters is established to obtain the mechanical efficiency of the bidirectional variable pump. S313. Based on the displacement of the bidirectional variable pump and the system pressure difference, combined with the relationship between the pressure difference and leakage characteristics of the liquid-driven hydrogen compressor, the system pressure difference, oil dynamic viscosity, servo motor speed and bidirectional variable pump displacement are used as key influencing parameters to obtain the volumetric efficiency of the bidirectional variable pump. S314. Based on the energy balance relationship of the servo motor, calculate the input mechanical power, and after deducting mechanical friction loss, iron loss and copper loss, obtain the output mechanical power and the servo motor efficiency. S315. Based on the system pressure difference, the actual input power is represented by the product of the piston force and the movement speed, and the ideal compression power is represented by the product of the pressure and flow rate in the compression chamber, thus obtaining the hydraulic cylinder efficiency. S316. Considering that efficiency losses accumulate at each stage in the entire power chain from servo motor input to compressor cylinder output, based on the power flow series transmission characteristics, the overall efficiency of the liquid-driven hydrogen compressor is constructed. for: ； in, For the mechanical efficiency of a bidirectional variable pump, For the volumetric efficiency of a bidirectional variable pump, For servo motor efficiency, For hydraulic cylinder efficiency.

4. The variable speed and variable displacement control method for suppressing reversing impact in a liquid-driven hydrogen compressor according to claim 3, characterized in that, Dynamic response time in S32 for: ； ； ； in, The first system response time, For the response time of the second system, This represents the initial steady-state displacement. The displacement corresponding to the target demand flow. This refers to the rate of change of displacement of a bidirectional variable pump. The rotational speed under initial steady state. The rotational speed corresponding to the target required flow rate. This refers to the equivalent rotational inertia of the servo motor and the pump. This represents the maximum output torque of the servo motor. This is the load torque referred to the servo motor shaft; S33 Optimization Evaluation Coefficient for: ； in, To find the optimal first weight coefficient, To find the optimal second weighting coefficient, + =1, To find the optimal first normalized reference value, To find the optimal second normalized benchmark value.

5. The variable speed and variable displacement control method for suppressing reversing impact in a liquid-driven hydrogen compressor according to claim 1, characterized in that, S4 include: S41. Based on the servo motor speed and the bidirectional variable pump displacement, a two-dimensional parameter space is constructed. S42. Based on the coupling relationship between servo motor speed and bidirectional variable pump displacement, the particle swarm algorithm is used to perform a global search in the two-dimensional parameter space to obtain the optimal parameter combination. S43. Evaluate the overall performance of the optimal parameter combination using the optimization evaluation coefficient. If the current optimal parameter combination fails to make the actual piston motion trajectory conform to the motion trajectory planned in S1 or the overall performance fails to reach the target range, continue to iterate and update the particle parameters. Specifically, the particle swarm optimization algorithm formula is as follows: ； ； in, For the first iteration For the i-th particle The particle velocity vector of the iteration step. For the i-th particle The particle velocity vector of the iteration step. For the i-th particle in the... The two-dimensional position vector of the iteration step. For the i-th particle in the... The two-dimensional position vector of the iteration step. For inertial weights, As the first learning factor, As the second learning factor, The first random number in the interval [0,1] The second random number in the interval [0,1] The historical best position of the i-th particle. This is the globally optimal position for the entire population.

6. The variable speed and variable displacement control method for suppressing reversing impact in a liquid-driven hydrogen compressor according to claim 3, characterized in that, The mechanical efficiency of the bidirectional variable pump is: ； in, This is the mechanical drag coefficient. The dynamic viscosity of the oil. For servo motor speed, For system pressure difference, This refers to the displacement of a bidirectional variable pump.

7. The variable speed and variable displacement control method for suppressing reversing impact in a liquid-driven hydrogen compressor according to claim 3, characterized in that, The volumetric efficiency of the bidirectional variable pump is: ； in, The laminar leakage coefficient is... The dynamic viscosity of the oil. For servo motor speed, For system pressure difference, This refers to the displacement of a bidirectional variable pump.

8. The variable speed and variable displacement control method for suppressing reversing impact in a liquid-driven hydrogen compressor according to claim 3, characterized in that, The efficiency of the servo motor is: ； in, For the servo motor output torque, For the angular velocity of the servo motor, For the mechanical losses of the servo motor, For the iron loss of the servo motor, This refers to the copper loss of the servo motor.

9. The variable speed and variable displacement control method for suppressing reversing impact in a liquid-driven hydrogen compressor according to claim 3, characterized in that, Hydraulic cylinder efficiency for: ； in, For the output force of the hydraulic cylinder, For the speed of the hydraulic cylinder, For system pressure difference, Input flow rate to the hydraulic cylinder.

10. An apparatus for the variable speed and variable displacement control method for suppressing reversing impact in a liquid-driven hydrogen compressor as described in any one of claims 1-9, characterized in that, It includes a servo motor, a bidirectional variable pump, and a hydraulic cylinder. The servo motor is connected to the bidirectional variable pump via a coupling. The two outlets of the bidirectional variable pump are connected to the two inlets of the hydraulic cylinder, driving the piston of the hydraulic cylinder to reciprocate. The piston drives the compression chamber to compress hydrogen. The hydraulic cylinder is equipped with a displacement sensor and a speed sensor to detect the displacement and speed of the piston in real time. A first pressure sensor and a second pressure sensor are respectively installed at the connection between the bidirectional variable pump and the hydraulic cylinder to detect the system pressure in real time. The displacement sensor, speed sensor, first pressure sensor, and second pressure sensor convert the collected data into electrical signals and feed them back to the controller. The controller outputs a control signal to the driver based on the electrical signal. The driver drives the servo motor to adjust its speed. At the same time, the controller directly controls the displacement of the bidirectional variable pump to achieve closed-loop control. A hot oil shuttle valve is also installed between the bidirectional variable pump and the hydraulic cylinder. The outlet of the hot oil shuttle valve is connected to the third relief valve, which is connected to the water-cooled oil inlet of the servo motor. The water-cooled oil outlet of the servo motor is connected to the cooler, together forming a heat exchange circuit. The high-temperature hot oil of the system is introduced into the cooling channel of the servo motor and then returned to the accumulator to realize thermal management.

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