A pump-controlled hydraulic system and method for wave compensation

Abstract

The present application relates to a kind of wave compensation-oriented pump control hydraulic system and method, system includes power module, flow asymmetric compensation module, oil supplement module, safety overflow module, pressure temperature detection module, actuator module and for the connection between each element hydraulic valve block, power module, pressure temperature detection module and a part of oil supplement module are connected to the upper side of hydraulic valve block, safety overflow module is connected to the right side and front side of hydraulic valve block, flow asymmetric compensation module is connected to the left and right sides of hydraulic valve block, pressure temperature detection module is connected to the front side of hydraulic valve block.The present application proposes a kind of wave compensation control method, the four-quadrant of pump control system is combined with wave motion situation analysis corresponding working condition, displacement compensation and energy effective utilization are carried out under corresponding working condition using pump control hydraulic system, effectively combine the four-quadrant of pump control system and common dc bus technology, realizes the energy management of pump control system and the high-performance control of hydraulic system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hydraulic pump control, in particular to a pump-controlled hydraulic system and method for wave compensation. BACKGROUND

[0002] The wave compensation system is a new type of hoisting operation system generated along with the increasing offshore replenishment operation. Ship will appear heave, roll and other movements due to the influence of waves and ocean currents in complex marine environment, which seriously affects the cargo replenishment rate. In order to eliminate these adverse factors, it is necessary to compensate for the waves of the ship crane.

[0003] The active wave compensation control system not only has the requirements of fast tracking, smooth operation, accurate positioning and other static and dynamic characteristics, but also overcomes the adverse effects of nonlinear factors, has certain robustness, and can realize stable operation under various working conditions, and achieves adaptability. Therefore, a new offshore replenishment wave compensation hydraulic control system is needed to avoid the impact of the relative motion of the replenishment material and bring safety hazards to the offshore workers. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a wave compensation hydraulic pump control system, which has the advantages of traditional wave compensation device control precision, and avoids the disadvantages of poor anti-pollution ability, low integration, serious energy waste, high equipment installation cost and inconvenient maintenance.

[0005] Specifically, the present application provides a wave compensation hydraulic pump control system, which comprises a hydraulic valve block, a power module, a safety overflow module, an oil supplementing module, a pressure and temperature detection module, a flow asymmetric compensation module, an actuator and a control system, wherein the power module, the safety overflow module, the oil supplementing module, the pressure and temperature detection module, the flow asymmetric compensation module and the actuator are respectively connected to the periphery of the hydraulic valve block.

[0006] The power module comprises a servo motor variable displacement hydraulic pump motor, and the servo motor is connected with the variable displacement hydraulic pump motor through a shaft coupling.

[0007] The actuator comprises a servo hydraulic cylinder, when the variable displacement hydraulic pump motor is in pump working condition, the oil outlet of the pump motor outputting high pressure oil is connected with the rod cavity of the servo hydraulic cylinder, and the oil outlet of the pump motor outputting low pressure oil is connected with the rodless cavity of the servo hydraulic cylinder, when the variable displacement hydraulic pump motor is in motor working condition, the oil outlet of the pump motor outputting low pressure oil is connected with the rod cavity of the servo hydraulic cylinder, and the oil outlet of the pump motor outputting high pressure oil is connected with the rodless cavity of the servo hydraulic cylinder.

[0008] The safety overflow module includes two safety overflow valves, the oil inlets of the two safety overflow valves are connected with the rod cavity and the rodless cavity of the oil cylinder respectively, the oil outlets of the two safety overflow valves are connected with the main oil circuit through the check valves, and the safety overflow module is used for stabilizing the system pressure in a preset range when the pressure overload occurs.

[0009] The oil compensation module is used for compensating the external leakage of the system and is connected with the hydraulic motor through the hydraulic control check valve and the check valve.

[0010] The pressure and temperature detection module is used for monitoring the system pressure and the temperature of the system in real time.

[0011] The flow asymmetric compensation module includes the hydraulic control check valves and the check valves, the hydraulic control check valves are connected on the two sides of the hydraulic pump motor respectively, the hydraulic control check valves are opened through the control oil circuit, and the check valves are reversed through the cooperation of the oil compensation module.

[0012] The control system is divided into four quadrant working conditions according to whether the resultant force and the movement direction of the hydraulic cylinder piston rod are the same or different, and the four quadrant working conditions are a first quadrant working condition, a second quadrant working condition, a third quadrant working condition and a fourth quadrant working condition.

[0013] When the hydraulic cylinder piston rod is stretched upwards, the first quadrant working condition and the fourth quadrant working condition are present, when the resultant force and the movement direction of the hydraulic cylinder piston rod are the same, that is, both are upwards, the first quadrant working condition is present, at this time, the variable displacement hydraulic pump motor is in the motor working condition, and the system charges the common DC bus; when the resultant force and the movement direction of the hydraulic cylinder piston rod are different, that is, the resultant force is downwards, the fourth quadrant working condition is present, at this time, the variable displacement hydraulic pump motor is in the pump working condition, and the power grid and the common DC bus discharge the system.

[0014] When the hydraulic cylinder piston rod is retracted downwards, the second quadrant working condition and the third quadrant working condition are present, when the resultant force and the movement direction of the hydraulic cylinder piston rod are the same, that is, both are downwards, the third quadrant working condition is present, at this time, the variable displacement hydraulic pump motor is in the motor working condition, the system charges the common DC bus, and the system is in the generator state; when the resultant force and the movement direction of the hydraulic cylinder piston rod are different, that is, the resultant force is upwards, the second quadrant working condition is present, at this time, the variable displacement hydraulic pump motor is in the pump working condition, the power grid and the common DC bus discharge the system, and the system is in the motor state.

[0015] When working, the control system detects the working state of the system, if the system is in the generator state, an energy management strategy is adopted, if the system is in the motor state, a high-performance control strategy is adopted, and speed closed-loop or displacement closed-loop control is performed according to the actual situation.

[0016] Then the position and speed of the oil cylinder are collected in real time, and the position and speed of the oil cylinder are respectively subtracted from the predetermined position and predetermined speed of the active wave compensation instruction, if the difference is within the threshold, it is determined that the control strategy reaches the control accuracy, and the position and speed of the oil cylinder are kept, if the difference is outside the threshold, it is determined that the control strategy does not reach the control accuracy, and the position and speed of the oil cylinder are adjusted until the control strategy reaches the control accuracy.

[0017] Preferably, the oil module is an accumulator connected with the hydraulic pump motor through a one-way valve and a hydraulic control one-way valve.

[0018] Preferably, the pressure and temperature detection module comprises a pressure sensor and a temperature sensor, the pressure sensor is connected to the two oil paths connected with the hydraulic pump motor and the hydraulic cylinder respectively, and the temperature sensor is connected to the oil path connected with the hydraulic pump motor and the accumulator.

[0019] Preferably, the controller of the control system is connected with the upper computer through a bus or a hardware cable signal, so as to realize the output force instruction given and the force signal feedback of the upper computer and the controller, and to realize the real-time monitoring of the alarm fault information of the system.

[0020] Another aspect of the present application also provides a control method of a wave compensation hydraulic pump control system, comprising the following steps:

[0021] S1, when the system is started, the control instruction is given, and the pressure and temperature of the system are monitored by the pressure and temperature detection module, if the high-pressure cavity pressure is too high, the low-pressure cavity pressure is too low, the system oil temperature is too high or the system oil temperature is too low, the system calls the motor open-loop control subroutine, and the motor is in standby state;

[0022] S2, the control system is divided into four quadrant working conditions according to the different combined external force and the movement direction of the hydraulic cylinder piston rod, the four quadrant working conditions are first quadrant working condition, second quadrant working condition, third quadrant working condition and fourth quadrant working condition respectively; the variable displacement hydraulic pump motor is in motor working condition and the servo motor is in generator state in the first quadrant working condition and the third quadrant working condition, the variable displacement hydraulic pump motor is in pump working condition and the servo motor is in motor state in the second quadrant working condition and the fourth quadrant working condition;

[0023] S3, when the pressure and temperature detection module feedbacks that the system pressure and temperature are normal, the system is ready for control, the active wave compensation control instruction is given, the working state of the system is detected, if it is generator state, the energy management strategy is adopted, if it is motor state, the high-performance control strategy is adopted, and the speed closed loop or displacement closed loop control is carried out according to the actual working state;

[0024] The specific judgment method is: the current efficiency of the hydraulic pump and the current efficiency of the servo motor are respectively calculated through the following formula:

[0025]

[0026] wherein, η P is the current efficiency of the hydraulic pump, η M is the current efficiency of the servo motor, η AP is the high efficiency zone efficiency of the hydraulic pump, η AM is the high efficiency zone efficiency of the servo motor, f(η P ) is a function between the efficiency of the hydraulic pump and the pressure flow, f(η M ) is a function between the efficiency of the servo motor and the speed torque, N is the speed, D p is the displacement of the variable displacement hydraulic pump motor.

[0027] The current efficiency of the hydraulic pump and the high efficiency zone efficiency of the hydraulic pump, the current efficiency of the servo motor and the high efficiency zone efficiency of the servo motor are respectively calculated by difference, such as the current efficiency of the hydraulic pump is less than the high efficiency zone efficiency of the hydraulic pump but the current efficiency of the servo motor is greater than or equal to the high efficiency zone efficiency of the servo motor, then the displacement closed loop control is adopted; such as the current efficiency of the servo motor is less than the high efficiency zone efficiency of the servo motor but the current efficiency of the hydraulic pump is greater than or equal to the high efficiency zone efficiency of the hydraulic pump, then the speed closed loop control is adopted; such as the current efficiency of the hydraulic pump is less than the high efficiency zone efficiency of the hydraulic pump and the current efficiency of the servo motor is less than or equal to the high efficiency zone efficiency of the servo motor, then the speed closed loop control and the displacement closed loop control are simultaneously adopted.

[0028] S4, the position and speed of the oil cylinder are collected in real time, and the position and speed of the oil cylinder are respectively subtracted from the target position and target speed of the active wave compensation instruction, if the difference is within the preset threshold, it is determined that the control strategy reaches the control accuracy, and the position and speed of the oil cylinder are kept; if the difference is outside the preset threshold, it is determined that the control strategy does not reach the control accuracy, and the position and speed of the oil cylinder are adjusted until the control strategy reaches the control accuracy.

[0029] Preferably, when the system fails, the control system alarms the upper computer and completes the pressure rapid unloading and closes the inlet valve.

[0030] Preferably, the speed closed loop control adjusts the speed of the servo motor according to the S-shaped speed curve of the servo motor.

[0031] The function relationship of the S-shaped speed curve of the motor is as follows:

[0032]

[0033] In the formula, V current is the current speed, V start is the initial speed, V target is the target speed, flexible is the curve stretching degree, t is the speed regulation time, T max is the speed regulation time span.

[0034] Preferably, the displacement closed-loop control specifically comprises the following sub-steps:

[0035] a. Calculate the stroke S of the piston of the variable displacement hydraulic pump motor p (α):

[0036]

[0037] b. Calculate the displacement D of the variable displacement hydraulic pump motor p (α):

[0038]

[0039] Wherein, α is the swash plate swing angle of the variable pump, unit: rad; β is the inclination angle between the swash plate and the piston of the variable displacement hydraulic pump motor when the swash plate is zero, unit: rad; A p is the area of the piston of the variable displacement hydraulic pump motor per unit angle, unit: m 2 / rad;

[0040] c. Calculate the transfer function G of the displacement closed-loop control PID (s):

[0041]

[0042] Wherein, K ap , K ai , K ad are the proportional, integral and differential coefficients of the displacement closed-loop controller of the amplifier respectively.

[0043] Preferably, the hydraulic system is connected with a common DC bus, when the direction of the impact force of the wave is the same as the direction of the movement of the hydraulic cylinder, that is, the direction of the oil movement is consistent with the direction of the combined external force, the system is in the first quadrant working condition or the third quadrant working condition, at this time, the servo motor is in the generator working condition, the variable displacement hydraulic pump motor is in the motor working condition, and the system charges the common DC bus;

[0044] When the direction of the impact force of the wave is opposite to the direction of the movement of the hydraulic cylinder, that is, the direction of the oil movement is opposite to the direction of the combined external force, the system is in the second quadrant working condition or the fourth quadrant working condition, at this time, the servo motor is in the motor working condition, the variable displacement hydraulic pump motor is in the pump working condition, the power grid and the common DC bus charge the system, and the energy of the power grid is consumed.

[0045] Compared with the prior art, the present application has the following beneficial effects:

[0046] (1) The overall structure of the present application adopts an integrated pipe-free connection mode, greatly improving the integration of the system; at the same time, the pump control system solution solves the problem of high requirement of the system on the cleanliness of the working medium oil, improves the reliability of the system; the control system adopts a control system composed of three parts of logic control, position closed loop control and system alarm control to ensure the high reliability of the system.

[0047] (2) The wave compensation hydraulic pump control system provided by the present application adopts the four-quadrant principle of the pump control system to divide the hydraulic system used for supply on the sea level into four working conditions, can make the system more clearly perform energy recovery and energy supply based on the movement of the wave, reduce energy loss and prolong the service life of the motor and other components.

[0048] (3) The wave compensation hydraulic pump control system provided by the present application adopts the common DC bus technology design, effectively combines the four-quadrant principle of the pump control system and the common DC bus recovery, reduces the energy waste of the system, and improves the energy reuse rate. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 is the hydraulic control principle diagram of the wave compensation hydraulic pump control system of the present application;

[0050] Figure 2 is the energy control block diagram of the wave compensation hydraulic pump control system of the present application;

[0051] Figure 3 is the functional block diagram of the wave compensation hydraulic pump control system of the present application;

[0052] Figure 4 is the logic control flow chart of the wave compensation hydraulic pump control system of the present application;

[0053] Figure 5 is the four-quadrant diagram of the wave compensation hydraulic pump control system of the present application;

[0054] Figure 6 is the right view of the wave compensation hydraulic pump control device of the present application;

[0055] Figure 7 is the left view of the wave compensation hydraulic pump control device of the present application.

[0056] Some of the attached diagrams are labeled as follows: 1-Servo motor; 2-Variable displacement hydraulic pump motor; 31-First hydraulic check valve; 32-Second hydraulic check valve; 41-First check valve; 42-Second check valve; 51-First relief valve; 52-Second relief valve; 61-First pressure sensor; 62-Second pressure sensor; 7-Temperature sensor; 8-Accumulator; 9-Servo hydraulic cylinder; 10-Power module; 11-Flow asymmetry compensation module; 12-Safety relief module; 13-Pressure and temperature detection module; 14-Replenishment module; 15-Actuator module. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0058] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "setting," and "connection" 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. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0059] Specifically, the present invention provides a hydraulic system for a press pump control system, which includes a hydraulic valve block, a power module, a safety relief module, a replenishment module, a pressure and temperature detection module, a flow asymmetry compensation module, an actuator, and a control system. The power module, the safety relief module, the replenishment module, the pressure and temperature detection module, the flow asymmetry compensation module, and the actuator are respectively connected to the periphery of the hydraulic valve block.

[0060] The power module includes a servo motor 1 and a variable displacement hydraulic pump motor 2. The servo motor 1 is connected to the variable displacement hydraulic pump motor 2 via a coupling. The power module serves as the power source for the system, providing the system with the required pressure and flow.

[0061] The flow asymmetry compensation module includes a first hydraulically controlled check valve 31, a second hydraulically controlled check valve 32, a first check valve 41, and a second check valve 42. These two sets of valves are connected to the oil lines of the hydraulic pump motor and the servo hydraulic cylinder, respectively. Because the rod-side and rodless chambers of the servo hydraulic cylinder have different volumes, the different fluid inflow and outflow during operation can cause insufficient oil supply or suction from the hydraulic pump motor. The hydraulically controlled check valve group and the check valve group work together to compensate for the deficiencies in oil supply and suction of the asymmetric cylinder.

[0062] The safety overflow module includes a first overflow valve 51 and a second overflow valve 52. When the system experiences a pressure overload during normal operation, the first overflow valve 51 and the second overflow valve 52 can stabilize the system pressure within a preset safe range.

[0063] The oil replenishment module is an accumulator 8, which is directly connected to the variable displacement hydraulic pump motor 2. The oil replenishment module can compensate for external leakage in the system and solve the problem of asymmetrical flow in the pump-controlled asymmetrical servo cylinder.

[0064] The pressure and temperature detection module can detect the system pressure and temperature in real time to ensure the safe operation of the system. The pressure and temperature detection module includes a first pressure sensor 61, a second pressure sensor 62, and a temperature sensor 7. The first pressure sensor 61 and the second pressure sensor 62 are respectively connected to the oil circuit of the variable displacement hydraulic pump motor 2 and the servo hydraulic cylinder 9, and the temperature sensor 7 is connected to the oil circuit of the variable displacement hydraulic pump motor 2 and the accumulator 8.

[0065] The actuator module includes a servo hydraulic cylinder 9. When the system is in motor mode, the high-pressure oil circuit of the variable displacement hydraulic pump motor 2 is the output oil circuit, flowing out of the servo hydraulic cylinder 9, and the low-pressure oil circuit is the input oil circuit, flowing into the servo hydraulic cylinder 9. When the system is in pump mode, the low-pressure oil circuit of the variable displacement hydraulic pump motor 2 is the output oil circuit, flowing out of the servo hydraulic cylinder 9, and the high-pressure oil circuit is the input oil circuit, flowing into the servo hydraulic cylinder 9.

[0066] like Figure 1 As shown, the entire wave compensation hydraulic pump control system consists of a servo motor 1, a variable displacement hydraulic pump motor 2, a first hydraulically controlled check valve 31, a second hydraulically controlled check valve 32, a first check valve 41, a second check valve 42, a first relief valve 51, a second relief valve 52, a first pressure sensor 61, a second pressure sensor 62, a temperature sensor 7, an accumulator 8, a servo hydraulic cylinder 9, and hydraulic valve blocks for connecting the various components. The variable displacement hydraulic pump motor 2 starts working under the drive of the servo motor 1. Hydraulic oil directly enters the rodless chamber of the servo hydraulic cylinder 9 through the channels in the hydraulic valve block, driving the servo cylinder 9 to extend. When the system generates abnormally high pressure and requires an overflow module, the relief valve 5 opens, and the high-pressure oil in the rodless chamber flows away through the relief valve 5.

[0067] The control system can be functionally divided into three equivalent parts: logic control, output force closed-loop control, and system alarm control. It can transmit output force commands and force signal feedback between the host computer and the controller via bus or hardware cable signals, and monitor system alarms and other fault information in real time to ensure stable system operation and reliable signal transmission. The controller can implement system logic control and high-performance force closed-loop control, and transmit control signals to the servo driver via bus or analog signals to achieve fast and stable operation of the servo motor.

[0068] In the specific operation process, the control system divides the working conditions into four quadrants based on whether the resultant external force and the direction of movement of the hydraulic cylinder piston rod are the same or different. The four quadrant working conditions are the first quadrant working condition, the second quadrant working condition, the third quadrant working condition and the fourth quadrant working condition.

[0069] When the hydraulic cylinder piston rod extends upward, there are first-quadrant and fourth-quadrant operating conditions. When the direction of the net external force is the same as the direction of movement of the hydraulic cylinder piston rod, that is, both are upward, it is the first-quadrant operating condition. At this time, the variable displacement hydraulic pump motor is in motor operating condition, and the system charges the common DC bus. When the direction is different from the direction of movement of the hydraulic cylinder piston rod, that is, the net external force is downward, it is the fourth-quadrant operating condition. At this time, the variable displacement hydraulic pump motor is in pump operating condition, and the power grid and the common DC bus discharge to the system.

[0070] When the hydraulic cylinder piston rod retracts downwards, there are two operating conditions: the second quadrant and the third quadrant. When the resultant external force and the direction of movement of the hydraulic cylinder piston rod are the same, i.e., both downwards, it is the third quadrant. At this time, the variable displacement hydraulic pump motor is in motor mode, the system charges the common DC bus, and the system is in generator mode. When the direction is different from the direction of movement of the hydraulic cylinder piston rod, i.e., the resultant external force is upwards, it is the second quadrant. At this time, the variable displacement hydraulic pump motor is in pump mode, the power grid and the common DC bus discharge to the system, and the system is in motor mode.

[0071] During operation, the control system detects the system's operating status. If it is in generator mode, an energy management strategy is adopted; if it is in motor mode, a high-performance control strategy is adopted, and speed closed-loop or displacement closed-loop control is performed according to the actual situation.

[0072] Then, the position and speed of the hydraulic cylinder are collected in real time, and the difference between the position and speed of the hydraulic cylinder and the predetermined position and speed of the active wave compensation command are calculated. If the difference is within a threshold, it is determined that the control strategy has achieved control accuracy, and the position and speed of the hydraulic cylinder are maintained; if the difference is outside the threshold, it is determined that the control strategy has not achieved control accuracy, and the position and speed of the hydraulic cylinder are adjusted until the control strategy achieves control accuracy. A schematic diagram of the energy control block diagram of the wave compensation hydraulic pump control system of the present invention is shown below. Figure 2 As shown. In practical applications, the value of this threshold can be set according to the required control precision, as long as it meets the required control precision.

[0073] Another aspect of the present invention provides a pump control method based on the above-described pump control system, the steps of which are as follows:

[0074] S1. When the system is turned on, a control command is given, and the pressure and temperature detection module monitors whether the system pressure and temperature are normal. If the high pressure chamber pressure is too high, the low pressure chamber pressure is too low, the system oil temperature is too high or the system oil temperature is too low, the system calls the motor open-loop control subroutine, and the motor is in standby mode.

[0075] S2. The control system is divided into four quadrant working conditions according to the different directions of the resultant external force and the movement of the hydraulic cylinder piston rod. The four quadrant working conditions are the first quadrant working condition, the second quadrant working condition, the third quadrant working condition and the fourth quadrant working condition. In the first quadrant working condition and the third quadrant working condition, the variable displacement hydraulic pump motor is in motor working condition and the servo motor is in generator working condition. In the second quadrant working condition and the fourth quadrant working condition, the variable displacement hydraulic pump motor is in pump working condition and the servo motor is in motor working condition.

[0076] S3. When the pressure and temperature detection module reports that the system pressure and temperature are normal, the system control is ready. An active wave compensation control command is given, and the system's working status is detected. If it is in generator status, an energy management strategy is adopted; if it is in motor status, a high-performance control strategy is adopted. Speed ​​closed-loop and displacement closed-loop control are performed according to different working states.

[0077] To simultaneously achieve displacement control and energy recovery, it is difficult to achieve both objectives with only adjustable speed as an input. Therefore, a displacement closed-loop control is further implemented. The displacement closed-loop control controls the pump outlet flow by adjusting the pump's displacement. The pump outlet flow is related to both speed and displacement. Thus, by adjusting the overall control strategy, the speed loop and displacement loop can work simultaneously to achieve the best control effect for displacement, speed, and energy recovery.

[0078] The specific determination method is as follows: calculate the current efficiency of the hydraulic pump and the current efficiency of the servo motor using the following formulas respectively:

[0079]

[0080] Where, η P η represents the current efficiency of the hydraulic pump. M η represents the current efficiency of the servo motor. AP For the high-efficiency range of the hydraulic pump, η AM For the high-efficiency zone efficiency of the servo motor, f(η) P f(η) is a function of the hydraulic pump efficiency and pressure / flow rate. M ) is a function relating servo motor efficiency to speed and torque.

[0081] The difference between the current efficiency of the hydraulic pump and its high-efficiency zone efficiency, and between the current efficiency of the servo motor and its high-efficiency zone efficiency, are calculated separately. If the current efficiency of the hydraulic pump is less than its high-efficiency zone efficiency but the current efficiency of the servo motor is greater than or equal to its high-efficiency zone efficiency, then displacement closed-loop control is adopted. If the current efficiency of the servo motor is less than its high-efficiency zone efficiency but the current efficiency of the hydraulic pump is greater than or equal to its high-efficiency zone efficiency, then speed closed-loop control is adopted. If the current efficiency of the hydraulic pump is less than its high-efficiency zone efficiency and the current efficiency of the servo motor is less than or equal to its high-efficiency zone efficiency, then both speed closed-loop control and displacement closed-loop control are adopted simultaneously.

[0082] When a system malfunctions, the control system sends an alarm to the host computer and quickly unloads the pressure, closing the intake valve.

[0083] Preferably, the speed closed-loop control adjusts the speed of the servo motor according to the S-shaped speed curve of the servo motor;

[0084] The S-curve speed curve of the motor has the following functional relationship:

[0085]

[0086] In the formula, V current V is the current speed. start Let V be the initial velocity. target The target speed is T, flexible is the curve stretching, and t is the speed adjustment time. max This refers to the time span for speed adjustment.

[0087] Preferably, the displacement closed-loop control specifically includes the following sub-steps:

[0088] a. Calculate the piston stroke S of the variable displacement hydraulic pump motor. p (α):

[0089]

[0090] b. Calculate the displacement D of the variable displacement hydraulic pump motor. p (α):

[0091]

[0092] Where α is the swashplate angle of the variable displacement pump, in rad; β is the tilt angle between the variable displacement hydraulic pump motor piston and the swashplate when the swashplate is at zero, in rad; A p The area per unit angle of the piston in a variable displacement hydraulic pump motor is expressed in meters (m²). 2 / rad;

[0093] c. Calculate the transfer function G for displacement closed-loop control. PID (s):

[0094]

[0095] In the formula K ap K ai K ad These are the proportional, integral, and derivative coefficients of the amplifier displacement closed-loop controller, respectively.

[0096] S4. Real-time acquisition of cylinder position and speed, and difference between cylinder position and speed and predetermined position and speed of active wave compensation command. If the difference is within the threshold, the control strategy is determined to have achieved control accuracy, and the cylinder position and speed are maintained. If the difference is within the threshold, the control strategy is determined to have not achieved control accuracy, and the cylinder position and speed are adjusted until the control strategy achieves control accuracy.

[0097] The structure and working principle of the present invention will be further explained below with reference to embodiments:

[0098] A functional block diagram of the wave-compensated hydraulic pump control system of the present invention is shown below. Figure 3 As shown, it includes: a wave-compensated hydraulic pump control system comprising a power module 10, a flow asymmetry compensation module 11, a safety overflow module 12, a pressure and temperature detection module 13, an oil replenishment module 14, and an actuator module 15. These modules cooperate with each other to achieve high-precision output force control. The functions of each module are described in detail below.

[0099] The power module 10 serves as the system's power source, providing the necessary pressure and flow. The flow asymmetry compensation module 11 addresses the difference in oil discharge and suction flow caused by cylinder asymmetry, ensuring more stable operation of the hydraulic cylinder. The safety relief module 12 stabilizes the system pressure within a safe range when abnormally high pressure occurs during normal system operation. The pressure and temperature detection module 13 ensures safe system operation by real-time monitoring of system pressure and temperature. The oil replenishment module 14 serves two purposes: compensating for external leakage and working with the flow asymmetry compensation module 11 to resolve the flow asymmetry problem of the pump-controlled asymmetric servo cylinder. The actuator module 15 executes the extension and retraction of the servo hydraulic cylinder.

[0100] The logic control flowchart of the wave compensation pump control system of the present invention is as follows: Figure 4 As shown. A detailed explanation follows:

[0101] The control logic of the wave compensation pump control system is as follows: After the system starts up, an active wave compensation control command is given, and the working status of the system is detected. If it is in generator status, an energy management strategy is adopted; if it is in motor status, a high-performance control strategy is adopted. Based on different strategies, the speed closed loop is achieved, and then the displacement closed loop is achieved. The feedback value of the cylinder position and speed is compared with the active wave compensation command to see if the control accuracy is achieved. If not, the signal is retransmitted to the speed closed loop; if it is achieved, the position is maintained.

[0102] A four-quadrant schematic diagram of the wave-compensated hydraulic pump control system of the present invention is shown below. Figure 5 As shown, the details are as follows:

[0103] like Figure 5 As shown, the pump is divided into four operating conditions based on different resultant external forces and velocity directions. Considering the vertical impact of waves on the ship during at-sea replenishment operations, it is assumed that the ship is subjected to an upward accelerating impact. Considering the movement direction of the servo hydraulic cylinder piston rod, when the piston rod extends outward, the velocity is upward. Considering the downward gravity of the external load, the impact force is upward. At this point, by comparing the magnitude of the forces, two possible resultant external force directions are identified. When both the resultant external force and velocity are upward, the system is in the first quadrant operating condition, which is the motor operating condition. The system will charge the common DC bus. When the force is downward and the velocity is upward, the system is in the fourth quadrant, which is the pump condition, and the power grid and common DC bus are discharging. Similarly, when the piston rod in the cylinder retracts inward, there are also two directions of the resultant external force. When the resultant external force is upward and the velocity is downward, the system is in the second quadrant, which is the pump condition, and the power grid and common DC bus are discharging. When both the resultant external force and the velocity are downward, the system is in the third quadrant, which is the motor condition, and the system will charge the common DC bus. By coordinating different charging and discharging conditions with the common DC bus, the system can effectively control energy recovery and efficient output.

[0104] Right view of the actual wave-compensating hydraulic pump control device of the present invention, as shown in the figure. Figure 6 As shown, the details are as follows:

[0105] like Figure 6 As shown, the hydraulic valve block connects the various components in the hydraulic system together. The power module 10 and the oil replenishment module 14 are connected to the upper surface of the hydraulic valve block. The first pressure sensor 61, which is part of the pressure and temperature detection module 13, is connected to the upper surface of the hydraulic valve block. The first hydraulically controlled check valve 31, which is part of the flow asymmetry compensation module 11, is connected to the front surface of the hydraulic valve block. The second pressure sensor 62, which is part of the pressure and temperature detection module 13, is connected to the front surface of the hydraulic valve block. The first relief valve 51, which is part of the safety relief module 12, is connected to the right surface of the hydraulic valve block. The first hydraulically controlled check valve 32, which is part of the flow asymmetry compensation module 11, is connected to the right surface of the hydraulic valve block. The execution module 15 is connected to the rear surface of the hydraulic valve block.

[0106] Left view of the actual wave-compensating hydraulic pump control device of the present invention, as shown in the figure. Figure 7 As shown, the details are as follows:

[0107] like Figure 7 As shown, the hydraulic valve block connects the various components of the hydraulic system together. Throttle valve 41 and throttle valve 42 are part of the flow asymmetry compensation module 11 and are connected to the left surface of the hydraulic valve block. Temperature sensor 7 is part of the pressure and temperature detection module 13 and is connected to the front surface of the hydraulic valve block. Second relief valve 52 is part of the safety relief module 12 and is connected to the front surface of the hydraulic valve block.

[0108] 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 hydraulic pump control method for wave compensation, characterized in that: The pump control hydraulic system of the hydraulic pump control method includes a hydraulic valve block, a power module, a safety relief module, a replenishment module, a pressure and temperature detection module, a flow asymmetry compensation module, an actuator, and a control system. The power module includes a servo motor and a variable displacement hydraulic pump motor. The actuator includes a servo hydraulic cylinder. When the variable displacement hydraulic pump motor is in pump mode, the oil port of the pump motor outputting high-pressure oil is connected to the rod chamber of the servo hydraulic cylinder, and the oil port of the pump motor outputting low-pressure oil is connected to the rodless chamber of the servo hydraulic cylinder. When the variable displacement hydraulic pump motor is in motor mode, the oil port of the pump motor outputting low-pressure oil is connected to the rod chamber of the servo hydraulic cylinder, and the oil port of the pump motor outputting high-pressure oil is connected to the rodless chamber of the hydraulic cylinder. The hydraulic pump control method includes the following steps: S1. When the system is turned on, a control command is given, and the pressure and temperature detection module monitors whether the system pressure and temperature are normal. If the high pressure chamber pressure is too high, the low pressure chamber pressure is too low, the system oil temperature is too high or the system oil temperature is too low, the system calls the motor open-loop control subroutine and the motor is in standby mode. S2. The control system is divided into four quadrant working conditions according to the different directions of the resultant external force and the piston rod movement of the hydraulic cylinder. The four quadrant working conditions are the first quadrant working condition, the second quadrant working condition, the third quadrant working condition and the fourth quadrant working condition. In the first quadrant working condition and the third quadrant working condition, the variable displacement hydraulic pump motor is in motor working condition and the servo motor is in generator working condition. In the second quadrant working condition and the fourth quadrant working condition, the variable displacement hydraulic pump motor is in pump working condition and the servo motor is in motor working condition. S3. When the pressure and temperature detection module reports that the system pressure and temperature are normal, the system gives an active wave compensation control command to detect the system's working status. If it is in generator status, an energy management strategy is adopted; if it is in motor status, a high-performance control strategy is adopted. Based on the actual working status, speed closed-loop control, displacement closed-loop control, or both speed closed-loop control and displacement closed-loop control are adopted simultaneously. The specific determination method is as follows: calculate the current efficiency of the hydraulic pump and the current efficiency of the servo motor using the following formulas respectively: ； in, The current efficiency of the hydraulic pump. This represents the current efficiency of the servo motor. For the high-efficiency zone of the hydraulic pump, For the high-efficiency zone of the servo motor, The efficiency of the hydraulic pump is a function of pressure and flow rate. The efficiency of the servo motor is a function of its speed and torque, where N is the speed. The displacement of the variable displacement hydraulic pump motor; The difference between the current efficiency of the hydraulic pump and its high-efficiency zone efficiency, and between the current efficiency of the servo motor and its high-efficiency zone efficiency, are calculated separately. If the current efficiency of the hydraulic pump is less than its high-efficiency zone efficiency but the current efficiency of the servo motor is greater than or equal to its high-efficiency zone efficiency, then displacement closed-loop control is adopted. If the current efficiency of the servo motor is less than its high-efficiency zone efficiency but the current efficiency of the hydraulic pump is greater than or equal to its high-efficiency zone efficiency, then speed closed-loop control is adopted. If the current efficiency of the hydraulic pump is less than its high-efficiency zone efficiency and the current efficiency of the servo motor is less than or equal to its high-efficiency zone efficiency, then both speed closed-loop control and displacement closed-loop control are adopted simultaneously. The speed closed-loop control adjusts the servo motor speed based on its S-curve speed curve; the functional relationship of the motor's S-curve speed curve is as follows. ； In the formula, At the current speed, The initial velocity, For the target speed, The curve stretching is represented by t, where t is the speed adjustment time. For the speed adjustment time span; Displacement closed-loop control specifically includes the following sub-steps: a. Calculate the piston stroke of the variable displacement hydraulic pump motor. : ； b. Calculate the displacement of the variable displacement hydraulic pump motor. : ； in, The swashplate angle of the variable pump is expressed in rad. The tilt angle between the variable displacement hydraulic pump motor plunger and the swashplate when the swashplate is zeroed, in rad. This refers to the area per unit angle of the piston in a variable displacement hydraulic pump motor, with units of... / rad; c. Calculate the transfer function of the displacement closed-loop control. : ； In the formula , , These are the proportional, integral, and derivative coefficients of the amplifier displacement closed-loop controller, respectively. S4. Real-time acquisition of cylinder position and speed, and difference between cylinder position and speed and target position and target speed of active wave compensation command. If the difference is within the preset threshold, the control strategy is determined to have achieved control accuracy, and the cylinder position and speed are maintained. If the difference is outside the preset threshold, the control strategy is determined to have not achieved control accuracy, and the cylinder position and speed are adjusted until the control strategy achieves control accuracy.

2. The hydraulic pump control method for wave compensation according to claim 1, characterized in that: When a system malfunctions, the control system sends an alarm to the host computer and quickly unloads the pressure, closing the intake valve.

3. The hydraulic pump control method for wave compensation according to claim 2, characterized in that: The hydraulic system is connected to a common DC bus. When the impact force of the wave is in the same direction as the movement of the hydraulic cylinder, that is, when the direction of the oil movement is in the same direction as the resultant external force, the system is in the first quadrant or the third quadrant. At this time, the servo motor is in generator mode, the variable displacement hydraulic pump motor is in motor mode, and the system charges the common DC bus. When the impact force of the wave is opposite to the direction of the hydraulic cylinder's movement, that is, when the direction of the oil movement is opposite to the direction of the net external force, the system is in the second quadrant or the fourth quadrant. At this time, the servo motor is in motor mode, the variable displacement hydraulic pump motor is in pump mode, and the power grid and common DC bus charge the system, consuming the power grid's energy.

4. The hydraulic pump control method for wave compensation according to claim 1, characterized in that: The safety relief module includes two safety relief valves. The oil inlets of the two safety relief valves are connected to the rod chamber and rodless chamber of the oil cylinder, respectively. The oil outlets of the two safety relief valves are connected to the main oil circuit through a check valve. The safety relief module is used to stabilize the system pressure within a preset range when pressure overload occurs. The oil replenishment module is used to compensate for external leakage of the system and is connected to the hydraulic motor through a hydraulically controlled check valve and a check valve. The pressure and temperature detection module is used to monitor the system pressure and temperature in real time. The flow asymmetry compensation module includes a hydraulically controlled check valve and a check valve, which are respectively connected to both sides of the hydraulic pump motor. The hydraulically controlled check valve is opened by controlling the oil circuit, and in conjunction with the oil replenishment module, the check valve is made to flow backward. The control system is divided into four quadrant working conditions based on whether the resultant external force and the direction of movement of the hydraulic cylinder piston rod are the same or different. The four quadrant working conditions are the first quadrant working condition, the second quadrant working condition, the third quadrant working condition and the fourth quadrant working condition. When the hydraulic cylinder piston rod extends upward, there are first-quadrant and fourth-quadrant operating conditions. When the direction of the net external force is the same as the direction of movement of the hydraulic cylinder piston rod, that is, both are upward, it is the first-quadrant operating condition. At this time, the variable displacement hydraulic pump motor is in motor operating condition, and the system charges the common DC bus. When the direction is different from the direction of movement of the hydraulic cylinder piston rod, that is, the net external force is downward, it is the fourth-quadrant operating condition. At this time, the variable displacement hydraulic pump motor is in pump operating condition, and the power grid and the common DC bus discharge to the system. When the hydraulic cylinder piston rod retracts downwards, there are two operating conditions: the second quadrant and the third quadrant. When the resultant external force and the direction of movement of the hydraulic cylinder piston rod are the same, i.e., both downwards, it is the third quadrant. At this time, the variable displacement hydraulic pump motor is in motor mode, the system charges the common DC bus, and the system is in generator mode. When the direction is different from the direction of movement of the hydraulic cylinder piston rod, i.e., the resultant external force is upwards, it is the second quadrant. At this time, the variable displacement hydraulic pump motor is in pump mode, the power grid and the common DC bus discharge to the system, and the system is in motor mode. During operation, the control system detects the system's operating status. If it is in generator mode, an energy management strategy is adopted; if it is in motor mode, a high-performance control strategy is adopted, and speed closed-loop or displacement closed-loop control is performed according to the actual situation. Then, the position and speed of the hydraulic cylinder are collected in real time, and the difference between the position and speed of the hydraulic cylinder and the predetermined position and speed of the active wave compensation command are calculated. If the difference is within the threshold, it is determined that the control strategy has achieved the control accuracy, and the position and speed of the hydraulic cylinder are maintained. If the difference is outside the threshold, it is determined that the control strategy has not achieved the control accuracy, and the position and speed of the hydraulic cylinder are adjusted until the control strategy achieves the control accuracy.

5. The hydraulic pump control method for wave compensation according to claim 1, characterized in that: The oil replenishment module is an accumulator, which is connected to the hydraulic pump motor via a check valve and a hydraulically controlled check valve.

6. The hydraulic pump control method for wave compensation according to claim 1, characterized in that: The pressure and temperature detection module includes a pressure sensor and a temperature sensor. The pressure sensor is connected to two oil lines connecting the hydraulic pump motor and the hydraulic cylinder, respectively, and the temperature sensor is connected to the oil line connecting the hydraulic pump motor and the accumulator.

7. The hydraulic pump control method for wave compensation according to claim 1, characterized in that: The controller of the control system communicates with the host computer via a bus or hardware cable signal, enabling the host computer to provide output force commands and force signal feedback to the controller, and to monitor the alarm and fault information of the system in real time.

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