Variable-speed variable-displacement electro-hydraulic power source control method and hydraulic system

Abstract

The invention relates to the technical field of hydraulic transmission, and provides a variable-speed variable-displacement electro-hydraulic power source control method and a hydraulic system.The method comprises the specific steps that the system pressure and the system flow at the current moment are obtained; the initial rotating speed of the servo motor at the current moment is detected, and the initial displacement of the two-way variable pump at the current moment is obtained; a genetic algorithm is used for obtaining the optimal displacement of the two-way variable pump and the optimal rotating speed of the servo motor; the servo motor is adjusted according to the optimal rotating speed of the servo motor, so that the two-way variable pump works at the combination point of the optimal displacement and the optimal rotating speed; and during the working period of the two-way variable pump, the steps are cyclically executed to realize real-time regulation and control of the electro-hydraulic power source. According to the method, the efficiency model and the dynamic response model of the electro-hydraulic power source are established, the intelligent optimization algorithm is used for conducting multi-target dynamic optimization on the efficiency and the response time of the electro-hydraulic power source, the rotating speed of the servo motor and the displacement of the two-way variable pump are controlled in a coordinated mode, and the electro-hydraulic power source works in a high-efficiency and high-response area.

Description

Technical Field

[0001] The invention belongs to the technical field of hydraulic transmission, and in particular relates to a control method for a variable speed and variable displacement electro-hydraulic power source and a hydraulic system. Background Art

[0002] The speed regulation methods of hydraulic systems include throttling speed regulation and volumetric speed regulation. The throttling speed regulation circuit controls and adjusts the flow entering or flowing out of the actuator by controlling the flow area of ​​the valve to achieve the purpose of speed regulation. Because of throttling loss, a large amount of energy is lost in the form of heat energy, so the overall efficiency of the system is not high. The volumetric speed regulation circuit controls and adjusts the flow entering or flowing out of the actuator by changing the displacement of the bidirectional variable pump and the speed of the servo motor. The flow output by the hydraulic pump is always adapted to the load flow. Compared with the throttling speed regulation circuit, there is no throttling or overflow loss, and it has a larger power-to-weight ratio.

[0003] There are three combinations of electro-hydraulic power sources in the volumetric speed control loop: variable speed fixed displacement electro-hydraulic power source, fixed speed variable displacement electro-hydraulic power source, and variable speed variable displacement electro-hydraulic power source. Among them, the variable speed variable displacement electro-hydraulic power source is a power module composed of a servo motor and a bidirectional variable pump to provide power for the volumetric speed control loop. The purpose of speed regulation is achieved by changing the displacement of the bidirectional variable pump and the speed of the servo motor. Power matching is achieved through composite control of speed and displacement. During system operation, the motor speed and hydraulic pump displacement can be dynamically adjusted according to the load power demand to improve system efficiency and reduce noise and heat. However, the dual variable coordinated control lacks a comprehensive control strategy that takes into account work performance, energy recovery efficiency, etc., and the control method is complex, and the system model is relatively idealized.

[0004] Therefore, it is necessary to propose a variable speed and variable displacement electro-hydraulic power source control method and hydraulic system. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a variable speed and variable displacement electro-hydraulic power source control method and hydraulic system. By establishing an electro-hydraulic power source efficiency model and a dynamic response model, an intelligent optimization algorithm is used to perform multi-objective dynamic optimization on the efficiency and response time of the electro-hydraulic power source, and the servo motor speed and the displacement of the bidirectional variable pump are coordinated and controlled to enable the electro-hydraulic power source to operate in a high efficiency and high response area.

[0006] The present invention discloses a variable speed and variable displacement electro-hydraulic power source control method, the steps comprising:

[0007] S1, obtain the current system pressure and system flow;

[0008] S2, detecting the initial speed of the servo motor at the current moment, and calculating the initial displacement of the bidirectional variable pump at the current moment;

[0009] S3, using genetic algorithm to obtain the optimal displacement of the bidirectional variable pump and the optimal speed of the servo motor;

[0010] S31, the expression of the multi-objective dynamic optimization model for the electro-hydraulic power source taking into account both efficiency and response time is as follows:

[0011] ;

[0012] Among them, h is the multi-objective dynamic optimization model of the electro-hydraulic power source that takes into account both efficiency and response time, among which T(V) is the dynamic response time of the electro-hydraulic power source, η (V) is the efficiency of the electro-hydraulic power source;

[0013] S32, create the initial population;

[0014] S33, using the initial population, taking the displacement of the bidirectional variable pump as the optimization variable, and using a genetic algorithm to perform multi-objective optimization based on a multi-objective dynamic optimization model that takes into account both efficiency and response time of the electro-hydraulic power source;

[0015] S34, select the individual with the highest fitness and output it as the optimization result;

[0016] S35, according to the output optimization result value, the optimal displacement of the bidirectional variable pump is obtained, and then the optimal speed of the servo motor is obtained according to the system flow in S1;

[0017] S4, adjusting the servo motor according to the optimal speed of the servo motor so that the bidirectional variable pump operates at a combination point of the obtained optimal displacement of the bidirectional variable pump and the optimal speed of the servo motor;

[0018] S5, during the operation of the bidirectional variable pump, S1-S4 are executed cyclically to achieve real-time regulation of the electro-hydraulic power source until the bidirectional variable pump stops working.

[0019] Preferably, in step S32, the initial population is composed of the bidirectional variable pump displacement ratio β, and all β values ​​in the initial population are between 0 and 1; the β expression is:

[0020] ;

[0021] Wherein, V is the displacement of the bidirectional variable pump, and V0 is the maximum displacement of the bidirectional variable pump.

[0022] Preferably, in step S31, the dynamic response time T(V) of the electro-hydraulic power source and the efficiency of the electro-hydraulic power source η (V) are obtained from the dynamic response time model of the electro-hydraulic power source and the efficiency model of the electro-hydraulic power source, respectively, as follows:

[0023] The expression of the dynamic response time model of the electro-hydraulic power source is as follows:

[0024] ;

[0025] Among them, T i1 is the duration of displacement change of the bidirectional variable pump under the i-th scheme, T i2 is the duration of the servo motor speed change under the i-th scheme; j is the number of schemes where the system flow changes from one steady-state value to another, and different speeds and displacements form different schemes; f min is the minimum dynamic response time;

[0026] The expression of the efficiency model of the electro-hydraulic power source is as follows:

[0027] ;

[0028] Among them, μ is the dynamic viscosity of the oil, p1 is the system pressure, q is the system flow, C v is the laminar flow resistance coefficient, C m is the mechanical resistance coefficient, β is the displacement ratio of the bidirectional variable pump, T s is the torque loss constant, V0 is the maximum displacement of the bidirectional variable pump, V is the displacement of the bidirectional variable pump, C s is the laminar leakage coefficient, T e is the output torque of the servo motor, ω is the output speed of the servo motor, P me is the mechanical loss of the servo motor, P Fe is the iron loss of the servo motor, P Cu is the copper loss of the servo motor, P dr is the servo motor drive loss.

[0029] Preferably, in step S31, the efficiency model of the electro-hydraulic power source is obtained according to the following expression:

[0030] ;

[0031] ;

[0032] ;

[0033] ;

[0034] in, η pm is the mechanical efficiency of the bidirectional variable pump, η pv is the volumetric efficiency of the bidirectional variable pump, η m is the servo motor efficiency, μ is the oil dynamic viscosity, p1 is the system pressure, n is the speed, C v is the laminar flow resistance coefficient, Cm is the mechanical resistance coefficient, β is the displacement ratio of the bidirectional variable pump, T s is the torque loss constant, V0 is the maximum displacement of the bidirectional variable pump, V is the displacement of the bidirectional variable pump, C s is the laminar leakage coefficient, T e is the output torque of the servo motor, ω is the output speed of the servo motor, P me is the mechanical loss of the servo motor, P Fe is the iron loss of the servo motor, P Cu is the copper loss of the servo motor, P dr is the servo motor drive loss.

[0035] Preferably, in step S31, the dynamic response time model of the electro-hydraulic power source is jointly effected by the dynamic response model of the bidirectional variable pump in the electro-hydraulic power source and the dynamic response of the servo motor in the electro-hydraulic power source, wherein the expression of the dynamic response model of the bidirectional variable pump in the electro-hydraulic power source is as follows:

[0036] ;

[0037] Among them, V2 is the displacement of the bidirectional variable pump corresponding to the target demand flow, V1 is the initial displacement of the bidirectional variable pump, T1 is the duration of displacement change of the bidirectional variable pump, α is the speed of displacement change, when the system pressure is constant, the speed of displacement change of the bidirectional variable pump is regarded as a constant value;

[0038] The expression of the dynamic response model of the servo motor in the electro-hydraulic power source is as follows:

[0039] ;

[0040] Where n1 is the initial speed of the servo motor, n2 is the speed of the servo motor corresponding to the target demand flow, p1 is the system pressure, V(t) is the function of the displacement of the bidirectional variable pump over time, which is given by the equipment parameters, J is the moment of inertia of the servo motor, T2 is the duration of the servo motor speed change, T max is the maximum output torque of the servo motor.

[0041] Preferably, the dynamic response model of the bidirectional variable pump in the electro-hydraulic power source and the dynamic response model of the servo motor in the electro-hydraulic power source are simplified to obtain:

[0042] When the servo motor speed change duration T2 is less than or equal to the bidirectional variable pump displacement change duration T1:

[0043] ;

[0044] When the duration T2 of the servo motor speed change is greater than the duration T1 of the bidirectional variable pump displacement change:

[0045] ;

[0046] When the system pressure is a certain value, the system flow changes from one steady-state value to another. Different speeds and displacements form different schemes, and different T1 and T2 values ​​are obtained. The maximum value is selected from the corresponding T1 and T2 as the dynamic response time of the electro-hydraulic power source of this scheme. The scheme with the shortest dynamic response time of the electro-hydraulic power source among different schemes is the optimal scheme for the dynamic response of the electro-hydraulic power source.

[0047] Another aspect of the present invention provides a variable speed and variable displacement electro-hydraulic power source hydraulic system for the above-mentioned variable speed and variable displacement electro-hydraulic power source control method, which includes a servo motor, a coupling, a two-way variable pump, a one-way valve, a relief valve, a pressure relay, a temperature sensor, a hydraulic cylinder, a pressure measuring joint, an accumulator, a controller, an electromagnetic reversing valve, a stop valve, a cooler, a valve block, a high-pressure oil circuit, a low-pressure oil circuit, an oil drain channel, a cooling oil circuit, a high-pressure channel, a low-pressure channel and a flow meter;

[0048] The valve block is provided with a high-pressure channel, a low-pressure channel and an oil drain channel;

[0049] The output shaft of the servo motor is connected to the input shaft of the bidirectional variable pump through a coupling;

[0050] The oil port of the bidirectional variable pump is installed in close contact with the wall surface of the valve block;

[0051] The first oil port of the bidirectional variable pump is connected to the hydraulic cylinder through the high-pressure hole and the high-pressure oil circuit in sequence;

[0052] The second oil port of the bidirectional variable pump is connected to the hydraulic cylinder through the low-pressure hole and the low-pressure oil circuit in sequence;

[0053] The third oil port of the bidirectional variable pump is connected to the oil drain channel;

[0054] The accumulator is connected to the oil drain hole;

[0055] The flow meter is connected in series to the high-pressure orifice, and the flow meter is connected to the controller.

[0056] Preferably, it further comprises a first pressure relay and a second pressure relay;

[0057] The first pressure relay is arranged on the high-pressure channel, the second pressure relay is arranged on the low-pressure channel, and both the first pressure relay and the second pressure relay are connected to the controller.

[0058] Preferably, it further comprises a first overflow valve and a second overflow valve;

[0059] The oil inlet of the first relief valve is connected to the high-pressure channel, the oil inlet of the second relief valve is connected to the low-pressure channel, and the oil outlets of the first relief valve and the second relief valve are both connected to the oil drain channel.

[0060] Preferably, it further comprises a first one-way valve and a second one-way valve;

[0061] The oil outlet of the first one-way valve is connected to the high-pressure channel, the oil outlet of the second one-way valve is connected to the low-pressure channel, and the oil inlets of the first one-way valve and the second one-way valve are both connected to the oil drain channel;

[0062] The cooling oil circuit is connected in parallel to the low-pressure duct, and the cooler is arranged on the cooling oil circuit;

[0063] The stop valve is arranged on the cooling oil circuit and is connected in series with the cooler;

[0064] The electromagnetic reversing valve is arranged on the low-pressure channel, and the oil inlet and outlet of the electromagnetic reversing valve are respectively connected to the cooling oil circuit.

[0065] Compared with the prior art, the present invention has the following advantages:

[0066] 1. Compared with the conventional variable speed fixed displacement and fixed speed variable displacement electro-hydraulic power source control methods, the variable speed variable displacement electro-hydraulic power source control method of the present invention has a larger speed regulation range and can adapt to more complex working conditions.

[0067] 2. A variable speed and variable displacement electro-hydraulic power source control method of the present invention uses a genetic algorithm to perform multi-objective dynamic optimization on the dynamic response time and working efficiency of a servo motor and a bidirectional variable pump. When the load or flow rate changes, optimization can be quickly performed under the new working condition to obtain a new speed and displacement combination point with high efficiency and high dynamic response, and the servo motor and the bidirectional variable pump are adjusted to work at the speed and displacement combination point. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 It is a control flow chart of the variable speed and variable displacement electro-hydraulic power source control method of the present invention;

[0069] Figure 2 It is a schematic diagram of the hydraulic principle of the variable speed and variable displacement electro-hydraulic power source hydraulic system of the present invention;

[0070] Figure 3 It is a functional block diagram of the variable speed and variable displacement electro-hydraulic power source hydraulic system of the present invention;

[0071] Figure 4 This is a simulation result diagram comparing the responses of three power units under flow rate changes from 5L / min to 10L / min in an embodiment of the present invention;

[0072] Figure 5This is a simulation result diagram comparing the energy efficiency of three power units under flow rate changes from 5L / min to 10L / min in an embodiment of the present invention;

[0073] Figure 6 This is a simulation result diagram comparing the responses of three power units under flow rate changes from 10L / min to 15L / min in an embodiment of the present invention;

[0074] Figure 7 This is a diagram showing the energy consumption simulation results of three power units responding to flow changes from 10L / min to 15L / min in an embodiment of the present invention.

[0075] Main reference numerals:

[0076] 1. Servo motor; 2. Coupling; 3. Bidirectional variable pump; 31. First oil port of bidirectional variable pump; 32. Second oil port of bidirectional variable pump; 33. Third oil port of bidirectional variable pump; 4. First one-way valve; 5. Second one-way valve; 6. First overflow valve; 7. Second overflow valve; 8. First pressure relay; 9. Second pressure relay; 10. Hydraulic cylinder; 11. Accumulator; 12. Controller; 13. Solenoid reversing valve; 14. Stop valve; 15. Cooler; 16. Valve block; 17. High-pressure oil circuit; 18. Low-pressure oil circuit; 19. Oil drain channel; 20. Cooling oil circuit; 21. High-pressure channel; 22. Low-pressure channel; 23. Flow meter. DETAILED DESCRIPTION

[0077] In order to fully describe the technical content, objectives and effects of the present invention, the following will be described in detail with reference to the accompanying drawings.

[0078] like Figure 1 As shown, the present invention provides a variable speed and variable displacement electro-hydraulic power source control method, and the specific implementation steps are:

[0079] S1, obtain the current system pressure and system flow;

[0080] Usually the system pressure is set within a certain range, and the system flow rate varies with the actual situation.

[0081] S2, detecting the initial speed of the servo motor at the current moment, and calculating the initial displacement of the bidirectional variable pump at the current moment;

[0082] According to the existing relationship formula between speed, displacement and flow: speed = flow / displacement, it can be known that the initial displacement of the bidirectional variable pump can be obtained through the initial speed of the servo motor and the system flow.

[0083] S3, using genetic algorithm to obtain the optimal displacement of the bidirectional variable pump and the optimal speed of the servo motor;

[0084] S31, the expression of establishing a multi-objective dynamic optimization model that takes into account both efficiency and response time of the electro-hydraulic power source is as follows:

[0085] ; (1)

[0086] Among them, h is the multi-objective dynamic optimization model of the electro-hydraulic power source that takes into account both efficiency and response time, among which T(V) is the dynamic response time of the electro-hydraulic power source, which is obtained from the dynamic response time model of the electro-hydraulic power source. η (V) is the efficiency of the electro-hydraulic power source, which is obtained from the efficiency model of the electro-hydraulic power source; the two models are described in detail below.

[0087] The dynamic response time model expression of the electro-hydraulic power source used in formula (1) is as follows:

[0088] ; (2)

[0089] Where, T(V) is the dynamic response time of the electro-hydraulic power source, T i1 is the duration of displacement change of the bidirectional variable pump under the i-th scheme, T i2 is the duration of the servo motor speed change under the i-th scheme; j is the number of different schemes consisting of different speeds and displacements when the system flow changes from one steady-state value to another; f min is the minimum dynamic response time;

[0090] In the present invention, a speed and flow rate constitute a scheme, and the speed and flow rate in the scheme also need to meet the speed = flow rate / displacement. When the system pressure is a certain value, the system flow rate changes from one steady-state value to another steady-state value. Different speeds and displacements constitute different schemes, and different T1 and T2 values ​​are obtained. The maximum value is selected from the corresponding T1 and T2 as the dynamic response time of the electro-hydraulic power source of this scheme, and then the scheme with the smallest dynamic response time of the electro-hydraulic power source is selected from different schemes, which is the optimal scheme for the dynamic response of the electro-hydraulic power source.

[0091] From each scheme, the dynamic response time of the electro-hydraulic power source is related to the duration of the displacement change of the bidirectional variable pump and the duration of the speed change of the servo motor, and depends on the longer response time. The duration of the displacement change of the bidirectional variable pump can be obtained from the dynamic response model of the bidirectional variable pump in the electro-hydraulic power source, and the duration of the speed change of the servo motor can be obtained from the dynamic response model of the servo motor in the electro-hydraulic power source.

[0092] The expression of the dynamic response model of the bidirectional variable pump in the electro-hydraulic power source is as follows:

[0093] ; (3)

[0094] Among them, V2 is the displacement of the bidirectional variable pump corresponding to the target demand flow, V1 is the initial displacement of the bidirectional variable pump, T1 is the duration of displacement change of the bidirectional variable pump, α is the speed of displacement change, when the system pressure is constant, the speed of displacement change of the bidirectional variable pump is regarded as a constant value;

[0095] The expression of the dynamic response model of the servo motor in the electro-hydraulic power source is as follows:

[0096] ; (4)

[0097] Where n1 is the initial speed of the servo motor, n2 is the speed of the servo motor corresponding to the target demand flow, p1 is the system pressure, V(t) is the function of the displacement of the bidirectional variable pump over time, which is given by the equipment parameters, J is the moment of inertia of the servo motor, T2 is the duration of the servo motor speed change, T max is the maximum output torque of the servo motor.

[0098] The dynamic response model of the bidirectional variable pump in the electro-hydraulic power source and the dynamic response model of the servo motor in the electro-hydraulic power source are simplified to obtain:

[0099] When the servo motor speed change duration T2 is less than or equal to the bidirectional variable pump displacement change duration T1:

[0100] ; (5)

[0101] When the duration T2 of the servo motor speed change is greater than the duration T1 of the bidirectional variable pump displacement change:

[0102] ; (6)

[0103] Formulas (5) and (6) can simplify the solution of T1 and T2 for each solution.

[0104] For T1 and T2 of the i-th solution among j solutions, we can use T i1 and T i2 Then, according to formula (2), the dynamic response time T(V) of the electro-hydraulic power source is obtained.

[0105] The expression of the efficiency model of the electro-hydraulic power source is as follows: ;

[0106] in, η (V) is the efficiency of the electro-hydraulic power source, μ is the dynamic viscosity of the oil, p1 is the system pressure, q is the system flow, C v is the laminar flow resistance coefficient, C m is the mechanical resistance coefficient, β is the displacement ratio of the bidirectional variable pump, Ts is the torque loss constant, V0 is the maximum displacement of the bidirectional variable pump, V is the displacement of the bidirectional variable pump, C s is the laminar leakage coefficient, T e is the output torque of the servo motor, ω is the output speed of the servo motor, P me is the mechanical loss of the servo motor, P Fe is the iron loss of the servo motor, P Cu is the copper loss of the servo motor, P dr is the servo motor drive loss.

[0107] The efficiency model of the electro-hydraulic power source used in formula (1) is obtained according to the following expression:

[0108] ;

[0109] ;

[0110] ;

[0111] ;

[0112] in, η (V) is the efficiency model of the electro-hydraulic power source, η pm is the mechanical efficiency of the bidirectional variable pump, η pv is the volumetric efficiency of the bidirectional variable pump, η m is the servo motor efficiency, μ is the oil dynamic viscosity, p1 is the system pressure, n is the speed, C v is the laminar flow resistance coefficient, C m is the mechanical resistance coefficient, β is the displacement ratio of the bidirectional variable pump, T s is the torque loss constant, V0 is the maximum displacement of the bidirectional variable pump, V is the displacement of the bidirectional variable pump, C s is the laminar leakage coefficient, T e is the output torque of the servo motor, ω is the output speed of the servo motor, P me is the mechanical loss of the servo motor, P Fe is the iron loss of the servo motor, P Cu is the copper loss of the servo motor, P dr is the servo motor drive loss.

[0113] S32, create the initial population;

[0114] The initial population is composed of the bidirectional variable pump displacement ratio β, and all β values ​​in the initial population are between 0 and 1; the β expression is:

[0115] ;

[0116] Wherein, V is the displacement of the bidirectional variable pump, and V0 is the maximum displacement of the bidirectional variable pump.

[0117] S33, using the initial population, taking the displacement V of the bidirectional variable pump as the optimization variable, and using a genetic algorithm to perform multi-objective optimization based on a multi-objective dynamic optimization model that takes into account both efficiency and response time of the electro-hydraulic power source;

[0118] The specific process of the genetic algorithm is: calculate the fitness of each individual in the population; randomly select individuals in the population to generate the next generation of population; calculate the fitness of each individual in the new generation of population; determine whether the termination condition is met; if so, execute step S34; if not, continue to generate the next generation of population and calculate the fitness.

[0119] S34, select the individual with the highest fitness and output it as the optimization result;

[0120] S35, according to the output optimization result β value, the optimal displacement of the bidirectional variable pump is obtained, and then the optimal speed of the servo motor is obtained according to the system flow q in S1;

[0121] S4, adjusting the servo motor according to the optimal speed of the servo motor so that the bidirectional variable pump operates at a combination point of the obtained optimal displacement of the bidirectional variable pump and the optimal speed of the servo motor;

[0122] S5, during the operation of the bidirectional variable pump, S1-S4 are executed cyclically, and the real-time control of the electro-hydraulic power source is achieved by defining the control of the servo motor speed. The control of the servo motor is not ended until the bidirectional variable pump stops working.

[0123] Another aspect of the present invention, as Figure 2As shown, a variable speed and variable displacement electro-hydraulic power source hydraulic system for a variable speed and variable displacement electro-hydraulic power source control method is provided, comprising a servo motor 1, a coupling 2, a bidirectional variable pump 3, a first oil port 31 of the bidirectional variable pump, a second oil port 32 of the bidirectional variable pump, a third oil port 33 of the bidirectional variable pump, a first one-way valve 4, a second one-way valve 5, a first overflow valve 6, a second overflow valve 7, a first pressure relay 8, a second pressure relay 9, a hydraulic cylinder 10, an accumulator 11, a controller 12, an electromagnetic reversing valve 13, a stop valve 14, a cooler 15, a valve block 16, a high-pressure oil circuit 17, a low-pressure oil circuit 18, an oil drain channel 19, a cooling oil circuit 20, a high-pressure channel 21, a low-pressure channel 22 and a flow meter 23. The output shaft of the servo motor 1 is connected to the input shaft of the bidirectional variable pump 3 through the coupling 2. The oil port of the bidirectional variable pump 3 is mounted in contact with the wall of the valve block 16. The first oil port 31 of the two-way variable pump is connected to the hydraulic cylinder 10 through the high-pressure channel 21 and the high-pressure oil circuit 17 in sequence, the second oil port 32 of the two-way variable pump is connected to the hydraulic cylinder 10 through the low-pressure channel 22 and the low-pressure oil circuit 18 in sequence, and the third oil port 33 of the two-way variable pump is connected to the oil drain channel 19. The accumulator 11 is connected to the oil drain channel 19. The oil inlet of the first relief valve 6 is connected to the high-pressure channel 21, the oil inlet of the second relief valve 7 is connected to the low-pressure channel 22, and the oil outlets of the first relief valve 6 and the second relief valve 7 are both connected to the oil drain channel 19. The oil outlet of the first check valve 4 is connected to the high-pressure channel 21, the oil outlet of the second check valve 5 is connected to the low-pressure channel 22, and the oil inlets of the first check valve 4 and the second check valve 5 are both connected to the oil drain channel 19. The flow meter 23 is connected in series with the high-pressure channel 21, and the flow meter 23 is connected to the controller 12. The first pressure relay 8 is arranged on the high-pressure channel 21, and the first pressure relay 8 is connected to the controller 12. The second pressure relay 9 is arranged on the low-pressure channel 22, and the second pressure relay 9 is connected to the controller 12. The cooling oil circuit 20 is connected in parallel with the low-pressure channel 22. The cooler 15 is arranged on the cooling oil circuit. The stop valve 14 is arranged on the cooling oil circuit and is connected in series with the cooler 15.

[0124] like Figure 3 As shown, the power module A includes a servo motor 1, which is connected to a bidirectional variable pump 3 through a coupling 2, serving as a power source for the system to provide the required power for the system.

[0125] The oil replenishment module B is used to compensate for the leakage of the system and absorb the flow pulsation of the system.

[0126] The safety relief module C is composed of a first relief valve 6 and a second relief valve 7. When pressure overload occurs during system operation, the system pressure is stabilized within a safe range.

[0127] Cooling module D: When the system is overheated, the cooling module starts working to reduce the system temperature.

[0128] The system parameter detection module E ensures the safe operation of the system by detecting the flow and pressure of the system in real time, and inputs the detected parameters into the controller 12.

[0129] The actuator module F, including the hydraulic cylinder 10, converts the hydraulic energy of the system into mechanical energy.

[0130] The controller module G, including the controller 12, calculates the collected data, finds the best working point and acts on the servo motor and the bidirectional variable pump.

[0131] A further technical solution is that the oil replenishment module B includes an accumulator 11 , and the accumulator 11 is connected to the oil drain channel 19 .

[0132] A further technical solution is that the safety overflow module C includes a first overflow valve 6, a second overflow valve 7, a first check valve 4 and a second check valve 5, the oil inlets of the first overflow valve 6 and the second overflow valve 7 are respectively connected to the high-pressure channel 21 and the low-pressure channel 22, and the oil outlets are both connected to the oil drain channel 19 and are respectively connected to the high-pressure channel 21 and the low-pressure channel 22 through the first check valve 4 and the second check valve 5.

[0133] A further technical solution is that the cooling module D includes an electromagnetic reversing valve 13, a cooler 15, a stop valve 14 and a cooling oil circuit 20, the electromagnetic reversing valve 13 is connected in series to the low-pressure channel 22, the cooling oil circuit 20 is connected in parallel to the low-pressure channel 22, the cooler 15 is arranged on the cooling oil circuit 20, and the stop valve 14 is arranged on the cooling oil circuit 20 and is connected in series with the cooler 15.

[0134] A further technical solution is that the system parameter detection module E includes a flow meter 23, a first pressure relay 8 and a second pressure relay 9, the flow meter 23 and the first pressure relay 8 are connected to the high-pressure channel 21 and connected to the controller 12, and the second pressure relay 9 is connected to the low-pressure channel 22 and connected to the controller 12.

[0135] The following is a further description of a variable speed and variable displacement electro-hydraulic power source control method of the present invention in conjunction with an embodiment:

[0136] In this specific embodiment, the variable speed and variable displacement electro-hydraulic power source control method of the present invention is simulated and verified.

[0137] The system overflow valve pressure is set to 4MPa, and the control oil pressure of the bidirectional variable pump is given to be 5MPa. When the system flow rate changes from 5L / min to 10L / min, and from 10L / min to 15L / min, the response characteristics and power input of the dual variable power unit, the fixed speed variable displacement power unit and the variable speed fixed displacement power unit using the variable speed and variable displacement electro-hydraulic power source control method are simulated and verified. The corresponding simulation results are shown in the figure below. Figure 4 , Figure 5 , Figure 6 and Figure 7 shown.

[0138] like Figure 4 and Figure 5 As shown in the figure, when the system flow changes from 5L / min to 10L / min, the flow response rise time of the dual variable power unit using the variable speed and variable displacement electro-hydraulic power source control method is 38ms, and the input power is 0.68kW. The flow response rise time of the fixed speed and variable displacement power unit is 57ms, and the input power is 0.73kW. The flow response rise time of the variable speed and fixed displacement power unit is 96ms, and the input power is 0.96kW, Figure 4 Among them, 41 is variable speed fixed displacement, 42 is fixed speed variable displacement, and 43 is variable speed variable displacement. Figure 5 Among them, 51 is variable speed fixed displacement, 52 is constant speed variable displacement, and 53 is variable speed variable displacement. It can be seen from the simulation results that the dual variable power unit using the variable speed variable displacement electro-hydraulic power source control method has both faster response and higher energy efficiency.

[0139] like Figure 6 and Figure 7 As shown in the figure, when the system flow changes from 10L / min to 15L / min, the flow response rise time of the dual variable power unit using the variable speed and variable displacement electro-hydraulic power source control method is 34ms, and the input power is 1.19kW. The flow response rise time of the fixed speed and variable displacement power unit is 39ms, and the input power is 1.21kW. The flow response rise time of the variable speed and fixed displacement power unit is 96ms, and the input power is 1.57kW. Figure 6 Among them, 61 is variable speed fixed displacement, 62 is fixed speed variable displacement, and 63 is variable speed variable displacement. Figure 7 Among them, 71 is variable speed fixed displacement, 72 is fixed speed variable displacement, and 73 is variable speed variable displacement. It can be seen from the simulation results that the dual variable power unit using the variable speed variable displacement electro-hydraulic power source control method also has faster response and higher energy efficiency under this working condition. In summary, the optimal matching control method based on genetic algorithm proposed in this paper can effectively take into account the dynamic response of the overall flow of the power unit and realize the efficient matching of the servo motor and the bidirectional variable pump.

[0140] The embodiments described above are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A variable speed and variable displacement electro-hydraulic power source control method, characterized in that: The steps include: S1, obtain the current system pressure and system flow; S2, detecting the initial speed of the servo motor at the current moment, and calculating the initial displacement of the bidirectional variable pump at the current moment; S3, using genetic algorithm to obtain the optimal displacement of the bidirectional variable pump and the optimal speed of the servo motor; S31, the expression of establishing a multi-objective dynamic optimization model that takes into account both efficiency and response time of the electro-hydraulic power source is as follows: ； Among them, h is the multi-objective dynamic optimization model of the electro-hydraulic power source that takes into account both efficiency and response time, among which T(V) is the dynamic response time of the electro-hydraulic power source, η (V) is the efficiency of the electro-hydraulic power source; S32, create the initial population; S33, using the initial population, taking the displacement of the bidirectional variable pump as the optimization variable, and using a genetic algorithm to perform multi-objective optimization based on a multi-objective dynamic optimization model that takes into account both efficiency and response time of the electro-hydraulic power source; S34, select the individual with the highest fitness and output it as the optimization result; S35, according to the output optimization result value, the optimal displacement of the bidirectional variable pump is obtained, and then the optimal speed of the servo motor is obtained according to the system flow in S1; S4, adjusting the servo motor according to the optimal speed of the servo motor so that the bidirectional variable pump operates at a combination point of the obtained optimal displacement of the bidirectional variable pump and the optimal speed of the servo motor; S5, during the operation of the bidirectional variable pump, S1-S4 are executed cyclically to achieve real-time regulation of the electro-hydraulic power source until the bidirectional variable pump stops working.

2. The variable speed and variable displacement electro-hydraulic power source control method according to claim 1, characterized in that: In step S32, the initial population is composed of the bidirectional variable pump displacement ratio β, and all β in the initial population are between 0 and 1; the β expression is: ； Wherein, V is the displacement of the bidirectional variable pump, and V0 is the maximum displacement of the bidirectional variable pump.

3. The variable speed and variable displacement electro-hydraulic power source control method according to claim 1, characterized in that: In step S31, the dynamic response time T(V) of the electro-hydraulic power source and the efficiency of the electro-hydraulic power source are calculated. η (V) are obtained from the dynamic response time model of the electro-hydraulic power source and the efficiency model of the electro-hydraulic power source, respectively, as follows: The expression of the dynamic response time model of the electro-hydraulic power source is as follows: ； Among them, T i1 is the duration of displacement change of the bidirectional variable pump under the i-th scheme, T i2 is the duration of the servo motor speed change under the i-th scheme; j is the number of schemes where the system flow changes from one steady-state value to another, and different speeds and displacements form different schemes; f min is the minimum dynamic response time; The expression of the efficiency model of the electro-hydraulic power source is as follows: ； Among them, μ is the dynamic viscosity of the oil, p1 is the system pressure, q is the system flow, C v is the laminar flow resistance coefficient, C m is the mechanical resistance coefficient, β is the displacement ratio of the bidirectional variable pump, T s is the torque loss constant, V0 is the maximum displacement of the bidirectional variable pump, V is the displacement of the bidirectional variable pump, C s is the laminar leakage coefficient, T e is the output torque of the servo motor, ω is the output speed of the servo motor, P me is the mechanical loss of the servo motor, P Fe is the iron loss of the servo motor, P Cu is the copper loss of the servo motor, P dr is the servo motor drive loss.

4. The variable speed and variable displacement electro-hydraulic power source control method according to claim 3, characterized in that: In step S31, the efficiency model of the electro-hydraulic power source is obtained according to the following expression: ； ； ； ； in, η pm is the mechanical efficiency of the bidirectional variable pump, η pv is the volumetric efficiency of the bidirectional variable pump, η m is the servo motor efficiency, μ is the oil dynamic viscosity, p1 is the system pressure, n is the speed, C v is the laminar flow resistance coefficient, C m is the mechanical resistance coefficient, β is the displacement ratio of the bidirectional variable pump, T s is the torque loss constant, V0 is the maximum displacement of the bidirectional variable pump, V is the displacement of the bidirectional variable pump, C s is the laminar leakage coefficient, T e is the output torque of the servo motor, ω is the output speed of the servo motor, P me is the mechanical loss of the servo motor, P Fe is the iron loss of the servo motor, P Cu is the copper loss of the servo motor, P dr is the servo motor drive loss.

5. The variable speed and variable displacement electro-hydraulic power source control method according to claim 3, characterized in that: In step S31, the dynamic response time model of the electro-hydraulic power source is jointly operated by the dynamic response model of the bidirectional variable pump in the electro-hydraulic power source and the dynamic response of the servo motor in the electro-hydraulic power source, wherein the expression of the dynamic response model of the bidirectional variable pump in the electro-hydraulic power source is as follows: ； Among them, V2 is the displacement of the bidirectional variable pump corresponding to the target demand flow, V1 is the initial displacement of the bidirectional variable pump, T1 is the duration of displacement change of the bidirectional variable pump, α is the speed of displacement change, when the system pressure is constant, the speed of displacement change of the bidirectional variable pump is regarded as a constant value; The expression of the dynamic response model of the servo motor in the electro-hydraulic power source is as follows: ； Where n1 is the initial speed of the servo motor, n2 is the speed of the servo motor corresponding to the target demand flow, p1 is the system pressure, V(t) is the function of the displacement of the bidirectional variable pump over time, which is given by the equipment parameters, J is the moment of inertia of the servo motor, T2 is the duration of the servo motor speed change, T max is the maximum output torque of the servo motor.

6. The variable speed and variable displacement electro-hydraulic power source control method according to claim 5, characterized in that: The dynamic response model of the bidirectional variable pump in the electro-hydraulic power source and the dynamic response model of the servo motor in the electro-hydraulic power source are simplified to obtain: When the servo motor speed change duration T2 is less than or equal to the bidirectional variable pump displacement change duration T1: ； When the duration T2 of the servo motor speed change is greater than the duration T1 of the bidirectional variable pump displacement change: ； When the system pressure is a certain value, the system flow changes from one steady-state value to another. Different speeds and displacements form different schemes, and different T1 and T2 values ​​are obtained. The maximum value is selected from the corresponding T1 and T2 as the dynamic response time of the electro-hydraulic power source of this scheme. The scheme with the shortest dynamic response time of the electro-hydraulic power source among different schemes is the optimal scheme for the dynamic response of the electro-hydraulic power source.

7. A variable speed and variable displacement electro-hydraulic power source hydraulic system, the variable speed and variable displacement electro-hydraulic power source hydraulic system is used in the variable speed and variable displacement electro-hydraulic power source control method according to any one of claims 1 to 6, characterized in that: It includes a servo motor, a coupling, a two-way variable pump, a one-way valve, a relief valve, a pressure relay, a temperature sensor, a hydraulic cylinder, a pressure measuring joint, an accumulator, a controller, an electromagnetic reversing valve, a stop valve, a cooler, a valve block, a high-pressure oil circuit, a low-pressure oil circuit, an oil drain channel, a cooling oil circuit, a high-pressure channel, a low-pressure channel and a flow meter; The valve block is provided with a high-pressure channel, a low-pressure channel and an oil drain channel; The output shaft of the servo motor is connected to the input shaft of the bidirectional variable pump through a coupling; The oil port of the bidirectional variable pump is installed in close contact with the wall surface of the valve block; The first oil port of the bidirectional variable pump is connected to the hydraulic cylinder through the high-pressure hole and the high-pressure oil circuit in sequence; The second oil port of the bidirectional variable pump is connected to the hydraulic cylinder through the low-pressure hole and the low-pressure oil circuit in sequence; The third oil port of the bidirectional variable pump is connected to the oil drain channel; The accumulator is connected to the oil drain hole; The flow meter is connected in series to the high-pressure orifice, and the flow meter is connected to the controller.

8. The variable speed and variable displacement electro-hydraulic power source hydraulic system according to claim 7, characterized in that: Also includes a first pressure relay and a second pressure relay; The first pressure relay is arranged on the high-pressure channel, the second pressure relay is arranged on the low-pressure channel, and both the first pressure relay and the second pressure relay are connected to the controller.

9. The variable speed and variable displacement electro-hydraulic power source hydraulic system according to claim 7, characterized in that: Also includes a first relief valve and a second relief valve; The oil inlet of the first relief valve is connected to the high-pressure channel, the oil inlet of the second relief valve is connected to the low-pressure channel, and the oil outlets of the first relief valve and the second relief valve are both connected to the oil drain channel.

10. The variable speed and variable displacement electro-hydraulic power source hydraulic system according to claim 7, characterized in that: Also includes a first one-way valve and a second one-way valve; The oil outlet of the first one-way valve is connected to the high-pressure channel, the oil outlet of the second one-way valve is connected to the low-pressure channel, and the oil inlets of the first one-way valve and the second one-way valve are both connected to the oil drain channel; The cooling oil circuit is connected in parallel to the low-pressure duct, and the cooler is arranged on the cooling oil circuit; The stop valve is arranged on the cooling oil circuit and is connected in series with the cooler; The electromagnetic reversing valve is arranged on the low-pressure channel, and the oil inlet and outlet of the electromagnetic reversing valve are respectively connected to the cooling oil circuit.

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