A control method and a hydraulic system for a variable-speed and variable-displacement electro-hydraulic power source

Abstract

The present invention relates to the technical field of hydraulic transmission, and provides a control method and a hydraulic system for a variable-speed variable-displacement electro-hydraulic power source. The specific steps are as follows: Obtain the system pressure and system flow rate at the current moment; Detect the initial speed of the servo motor at the current moment to obtain the initial displacement of the bidirectional variable pump at the current moment; Use a genetic algorithm to obtain the optimal displacement of the bidirectional variable pump and the optimal speed of the servo motor; Adjust the servo motor according to the optimal speed of the servo motor so that the bidirectional variable pump operates at the combination point of the optimal displacement and the optimal speed; During the operation of the bidirectional variable pump, the above steps are cyclically executed to achieve real-time control of the electro-hydraulic power source. By establishing an efficiency model and a dynamic response model of the electro-hydraulic power source, the present invention uses an intelligent optimization algorithm to perform multi-objective dynamic optimization on the efficiency and response time of the electro-hydraulic power source, and coordinately controls the speed of the servo motor and the displacement of the bidirectional variable pump, so that the electro-hydraulic power source operates in a high-efficiency and high-response area.

Description

Technical Field

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

[0002] The speed regulation methods of hydraulic systems include throttle speed regulation and volume speed regulation. Among them, the throttle speed regulation circuit controls and adjusts the flow rate entering or leaving the actuator by changing the flow area of the control valve to achieve the purpose of speed regulation. Due to the existence of throttle losses in throttle speed regulation, a large amount of energy is dissipated in the form of heat, so the overall efficiency of the system is not high. The volume speed regulation circuit controls and adjusts the flow rate entering or leaving the actuator by changing the displacement of the bidirectional variable pump and the speed of the servo motor. The flow rate output by the hydraulic pump is always adapted to the load flow rate. Compared with the throttle speed regulation circuit, there are no throttle and overflow losses, and it has a large power-to-weight ratio.

[0003] There are three combination schemes for the electro-hydraulic power source in the volume speed regulation circuit: 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 consists of a power module composed of a servo motor and a bidirectional variable pump, which provides power for the volume speed regulation circuit. By changing the displacement of the bidirectional variable pump and the speed of the servo motor, the purpose of speed regulation is achieved. Through the composite control of speed and displacement, power matching is realized. During the operation of the system, the motor speed and the displacement of the hydraulic pump can be dynamically adjusted according to the load power demand, improving the system efficiency, reducing noise and heat generation. However, the dual-variable coordinated control lacks a comprehensive control strategy that takes into account aspects such as working performance and energy recovery efficiency, and the control method is complex, and the system model is relatively idealized.

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

[0005] Aiming at the problems existing in the prior art, the present invention provides a control method and a hydraulic system for a variable-speed and variable-displacement electro-hydraulic power source. By establishing an efficiency model and a dynamic response model of the electro-hydraulic power source, a multi-objective dynamic optimization is performed on the efficiency and response time of the electro-hydraulic power source using an intelligent optimization algorithm, and the speed of the servo motor and the displacement of the bidirectional variable pump are coordinately controlled to make the electro-hydraulic power source work in a high-efficiency and high-response area.

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

[0007] S1, obtaining the system pressure and system flow rate at the current moment;

[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. Use the genetic algorithm to obtain the optimal displacement of the bidirectional variable pump and the optimal speed of the servo motor;

[0010] S31. Establish the expression of the multi-objective dynamic optimization model of the electro-hydraulic power source that takes into account both efficiency and response time as follows:

[0011] ;

[0012] where h is the multi-objective dynamic optimization model of the electro-hydraulic power source that takes into account both efficiency and response time. Among them, 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 an initial population;

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

[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, obtain the optimal displacement of the bidirectional variable pump, and then obtain the optimal speed of the servo motor according to the system flow rate in S1;

[0017] S4. Adjust the servo motor according to the optimal speed of the servo motor so that the bidirectional variable pump works at the combined 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, loop through S1 - S4 to achieve real-time control 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 displacement ratio β of the bidirectional variable pump. All values of β in the initial population range from 0 to 1; the expression of β is:

[0020] ;

[0021] where V is the displacement of the bidirectional variable pump, and V 0 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 η (V) of the electro-hydraulic power source 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] where, T i1 is the duration of the displacement change of the bidirectional variable pump under the i-th scheme, and T i2 is the duration of the rotational speed change of the servo motor under the i-th scheme; j is the number of different schemes composed of different rotational speeds and displacements when the system flow rate changes from one steady-state value to another; f min is the minimum value of the dynamic response time;

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

[0027] ;

[0028] where, μ is the dynamic viscosity of the oil, p 1 is the system pressure, q is the system flow rate, 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, V 0 is the maximum displacement of the bidirectional variable pump, V is the displacement of the bidirectional variable pump, C s is the laminar flow leakage coefficient, T e is the output torque of the servo motor, ω is the output rotational 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 loss of the servo motor driver.

[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] where, η pm is the mechanical efficiency of the bidirectional variable pump, η pv is the volumetric efficiency of the bidirectional variable pump, η mis the efficiency of the servo motor, μ is the dynamic viscosity of the oil, p 1 is the system pressure, n is the rotational speed, C v is the laminar flow resistance coefficient, C m is the mechanical resistance coefficient, β is the displacement ratio of the bi-directional variable pump, T s is the torque loss constant, V 0 is the maximum displacement of the bi-directional variable pump, V is the displacement of the bi-directional variable pump, C s is the laminar flow leakage coefficient, T e is the output torque of the servo motor, ω is the output rotational 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 loss of the servo motor driver.

[0035] Preferably, in step S31, the dynamic response time model of the electro-hydraulic power source is the combined action of the dynamic response model of the bi-directional variable pump in the electro-hydraulic power source and the dynamic response of the servo motor in the electro-hydraulic power source. Among them, the expression of the dynamic response model of the bi-directional variable pump in the electro-hydraulic power source is as follows:

[0036] ;

[0037] Among them, V 2 is the displacement of the bi-directional variable pump corresponding to the target demand flow rate, V 1 is the initial displacement of the bi-directional variable pump, T 1 is the duration of the displacement change of the bi-directional variable pump, α is the speed of the displacement change. When the system pressure is constant, the speed of the displacement change of the bi-directional 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] Among them, n 1 is the initial rotational speed of the servo motor, n 2 is the rotational speed of the servo motor corresponding to the target demand flow rate, p 1 is the system pressure, V(t) is the function of the displacement of the bi-directional variable pump changing with time, which is given by the equipment parameters, J is the moment of inertia of the servo motor, T 2 is the duration of the rotational speed change of the servo motor, T max is the maximum output torque of the servo motor.

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

[0042] When the duration T of the change in the rotational speed of the servo motor 2 is less than or equal to the duration T of the change in the displacement of the bi-directional variable pump 1 then:

[0043] ;

[0044] When the duration T of the change in the rotational speed of the servo motor 2 is greater than the duration T of the change in the displacement of the bi-directional variable pump 1 then:

[0045] ;

[0046] When the system pressure is a certain value, the system flow rate changes from one steady-state value to another steady-state value. Different rotational speeds and displacements form different schemes, resulting in different values of T 1 and T 2 values. The maximum value is selected from the corresponding T 1 and T 2 as the dynamic response time of the electro-hydraulic power source for this scheme. The scheme with the minimum 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] On the other hand, the present invention provides a variable-speed variable-displacement electro-hydraulic power source hydraulic system for the above-mentioned variable-speed variable-displacement electro-hydraulic power source control method, which includes a servo motor, a coupling, a bi-directional variable pump, a check valve, a relief valve, a pressure relay, a temperature sensor, a hydraulic cylinder, a pressure measuring joint, an accumulator, a controller, an electromagnetic directional valve, a stop valve, a cooler, a valve block, a high-pressure oil circuit, a low-pressure oil circuit, an oil drain passage, a cooling oil circuit, a high-pressure passage, a low-pressure passage, and a flow meter;

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

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

[0050] The oil ports of the bi-directional variable pump are fitted and installed with the wall surface of the valve block;

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

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

[0053] The third oil port of the bi-directional variable pump is connected to the oil drain passage;

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

[0055] The flowmeter is connected in series to the high-pressure passage, and the flowmeter is connected to the controller.

[0056] Preferably, a first pressure relay and a second pressure relay are further included;

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

[0058] Preferably, a first overflow valve and a second overflow valve are further included;

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

[0060] Preferably, a first check valve and a second check valve are further included;

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

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

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

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

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

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

[0067] 2. The variable-speed 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 the servo motor and the bidirectional variable pump. When the load or the flow rate changes, it can quickly perform optimization under the new working conditions to obtain a new high-efficiency and high-dynamic-response speed-displacement combination point, and adjust the servo motor and the bidirectional variable pump to work at this speed-displacement combination point. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0069] Figure 2 This 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 This is a schematic diagram of the functional blocks 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 of the response comparison of three power units under the flow rate change from 5 L / min to 10 L / min in the embodiment of the present invention;

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

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

[0074] Figure 7 This is a simulation result diagram of the response energy consumption of three power units under the flow rate change from 10 L / min to 15 L / min in the embodiment of the present invention.

[0075] Main reference numerals:

[0076] 1. Servo motor; 2. Coupling; 3. Bidirectional variable pump; 31. First oil port of the bidirectional variable pump; 32. Second oil port of the bidirectional variable pump; 33. Third oil port of the 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. Electromagnetic directional valve; 14. Stop valve; 15. Cooler; 16. Valve block; 17. High-pressure oil circuit; 18. Low-pressure oil circuit; 19. Drainage hole; 20. Cooling oil circuit; 21. High-pressure hole; 22. Low-pressure hole; 23. Flowmeter. Detailed implementation manners

[0077] To elaborate on the technical content, achieved objectives and effects of the present invention, the following will be described in detail with reference to the accompanying drawings of the specification.

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

[0079] S1. Obtain the system pressure and system flow rate at the current moment;

[0080] Generally, the system pressure is set within a certain range, and the system flow rate changes according to the actual situation.

[0081] S2. Detect the initial rotational speed of the servo motor at the current moment, and calculate the initial displacement of the bidirectional variable pump at the current moment.

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

[0083] S3. Use the genetic algorithm to obtain the optimal displacement of the bidirectional variable pump and the optimal rotational speed of the servo motor.

[0084] S31. Establish the expression of the multi-objective dynamic optimization model of the electro-hydraulic power source that takes into account both efficiency and response time 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 them, 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 following will explain these two models in detail respectively.

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

[0088] ; (2)

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

[0090] In the present invention, one rotational speed and flow rate form one scheme, and the rotational speed and flow rate in the scheme also need to conform to rotational 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, and different rotational speeds and displacements form different schemes, obtaining different T 1 and T 2 values. Select the maximum value from the corresponding T 1 and T 2 as the dynamic response time of the electro-hydraulic power source for this scheme, and then select the scheme with the minimum dynamic response time of the electro-hydraulic power source from different schemes, which is the optimal scheme of the dynamic response of the electro-hydraulic power source.

[0091] From each solution, the dynamic response time of the electro-hydraulic power source is related to the duration of the displacement change of the bi-directional variable pump and the duration of the rotational speed change of the servo motor, and depends on the one with the longer response time. The duration of the displacement change of the bi-directional variable pump can be obtained from the dynamic response model of the bi-directional variable pump in the electro-hydraulic power source, and the duration of the rotational 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 bi-directional variable pump in the electro-hydraulic power source is as follows:

[0093] ; (3)

[0094] Wherein, V 2 is the displacement of the bi-directional variable pump corresponding to the target demand flow rate, V 1 is the initial displacement of the bi-directional variable pump, T 1 is the duration of the displacement change of the bi-directional variable pump, α is the speed of the displacement change, and when the system pressure is constant, the speed of the displacement change of the bi-directional 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] Wherein, n 1 is the initial rotational speed of the servo motor, n 2 is the rotational speed of the servo motor corresponding to the target demand flow rate, p 1 is the system pressure, V(t) is the function of the displacement of the bi-directional variable pump changing with time, which is given by the equipment parameters, J is the moment of inertia of the servo motor, T 2 is the duration of the rotational speed change of the servo motor, T max is the maximum output torque of the servo motor.

[0098] Simplify the dynamic response model of the bi-directional variable pump in the electro-hydraulic power source and the dynamic response model of the servo motor in the electro-hydraulic power source, and obtain:

[0099] When the duration of the rotational speed change of the servo motor T 2 is less than or equal to the duration of the displacement change of the bi-directional variable pump T 1 :

[0100] ; (5)

[0101] When the duration of the rotational speed change of the servo motor T 2 is greater than the duration of the displacement change of the bi-directional variable pump T 1 :

[0102] ; (6)

[0103] Equations (5) and (6) can simplify the solution of T for each scheme 1 and T 2 .

[0104] For the T 1 and T 2 of the i-th scheme among the j schemes, T i1 and T i2 can be used to represent. Then, according to Equation (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] ;

[0107] where η (V) is the efficiency of the electro-hydraulic power source, μ is the dynamic viscosity of the oil, p 1 is the system pressure, q is the system flow rate, C v is the laminar flow resistance coefficient, C m is the mechanical resistance coefficient, β is the displacement ratio of the bi-directional variable pump, T s is the torque loss constant, V 0 is the maximum displacement of the bi-directional variable pump, V is the displacement of the bi-directional variable pump, C s is the laminar flow 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 loss of the servo motor driver.

[0108] The efficiency model of the electro-hydraulic power source used in Equation (1) is obtained according to the following expression:

[0109] ;

[0110] ;

[0111] ;

[0112] ;

[0113] where η (V) is the efficiency model of the electro-hydraulic power source, η pm is the mechanical efficiency of the bi-directional variable pump, ηpv is the volumetric efficiency of the bidirectional variable pump, η m is the efficiency of the servo motor, μ is the dynamic viscosity of the oil, p 1 is the system pressure, n is the rotational 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, V 0 is the maximum displacement of the bidirectional variable pump, V is the displacement of the bidirectional variable pump, C s is the laminar flow leakage coefficient, T e is the output torque of the servo motor, ω is the output rotational 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 loss of the servo motor driver.

[0114] S32, create the initial population;

[0115] The initial population is composed of the displacement ratio β of the bidirectional variable pump. All values of β in the initial population range from 0 to 1; the expression of β is:

[0116] ;

[0117] where, V is the displacement of the bidirectional variable pump, V 0 is the maximum displacement of the bidirectional variable pump.

[0118] S33, use the initial population, take the displacement V of the bidirectional variable pump as the optimization variable, and perform multi-objective optimization using the genetic algorithm according to the multi-objective dynamic optimization model that takes into account the efficiency and response time of the electro-hydraulic power source;

[0119] 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 the population; calculate the fitness of each individual in the new generation of the population; judge whether the termination condition is met; if so, execute step S34; if not, continue to generate the next generation of the population and calculate the fitness.

[0120] S34, select the individual with the highest fitness and output it as the optimization result;

[0121] S35, according to the output optimization result β value, obtain the optimal displacement of the bidirectional variable pump, and then obtain the optimal rotational speed of the servo motor according to the system flow rate q in S1;

[0122] S4, adjust the servo motor according to the optimal rotational speed of the servo motor so that the bidirectional variable pump operates at the combined point of the obtained optimal displacement of the bidirectional variable pump and the optimal rotational speed of the servo motor;

[0123] During the operation of the S5 two-way variable pump, S1 - S4 are executed cyclically. By defining the regulation of the servo motor speed, the real-time regulation of the electro-hydraulic power source is achieved. The regulation of the servo motor ends only when the two-way variable pump stops working.

[0124] On the other hand of the present invention, as Figure 2 shown, a variable-speed variable-displacement electro-hydraulic power source hydraulic system for a variable-speed variable-displacement electro-hydraulic power source control method is provided, including a servo motor 1, a coupling 2, a two-way variable pump 3, a first oil port 31 of the two-way variable pump, a second oil port 32 of the two-way variable pump, a third oil port 33 of the two-way 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 directional 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 passage 19, a cooling oil circuit 20, a high-pressure passage 21, a low-pressure passage 22, and a flowmeter 23. The output shaft of the servo motor 1 is connected to the input shaft of the two-way variable pump 3 through the coupling 2. The oil ports of the two-way variable pump 3 are fitted and installed on the wall surface 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 passage 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 passage 22 and the low-pressure oil circuit 18 in sequence. The third oil port 33 of the two-way variable pump is connected to the oil drain passage 19. The accumulator 11 is connected to the oil drain passage 19. The inlet port of the first overflow valve 6 is connected to the high-pressure passage 21. The inlet port of the second overflow valve 7 is connected to the low-pressure passage 22. And the outlet ports of the first overflow valve 6 and the second overflow valve 7 are both connected to the oil drain passage 19. The outlet port of the first one-way valve 4 is connected to the high-pressure passage 21. The outlet port of the second one-way valve 5 is connected to the low-pressure passage 22. And the inlet ports of the first one-way valve 4 and the second one-way valve 5 are both connected to the oil drain passage 19. The flowmeter 23 is connected in series with the high-pressure passage 21 and is connected to the controller 12. The first pressure relay 8 is arranged on the high-pressure passage 21 and is connected to the controller 12. The second pressure relay 9 is arranged on the low-pressure passage 22 and is connected to the controller 12. The cooling oil circuit 20 is connected in parallel with the low-pressure passage 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.

[0125] As Figure 3 shown, the power module A includes a servo motor 1. The servo motor 1 is connected to the two-way variable pump 3 through the coupling 2 and serves as the power source of the system to provide the required power for the system.

[0126] The oil replenishment module B is used to compensate for the leakage of the system and at the same time absorb the flow pulsation of the system.

[0127] The safety overflow module C is composed of a first overflow valve 6 and a second overflow valve 7. When the system operation has pressure overload, it stabilizes the system pressure within a safe range.

[0128] The cooling module D starts to work when the system overheats to reduce the system temperature.

[0129] The system parameter detection module E ensures the safe operation of the system by detecting the flow rate and pressure of the system in real time, and at the same time inputs the detected parameters into the controller 12.

[0130] The actuator module F includes a hydraulic cylinder 10, which converts the hydraulic energy of the system into mechanical energy.

[0131] The controller module G includes a controller 12, which calculates the collected data to find the optimal operating point and acts on the servo motor and the bidirectional variable pump.

[0132] A further technical solution lies in that the oil replenishing module B includes an accumulator 11, and the accumulator 11 is connected to the oil drain passage 19.

[0133] A further technical solution lies in 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 inlet ports of the first overflow valve 6 and the second overflow valve 7 are respectively connected to the high-pressure passage 21 and the low-pressure passage 22, and the outlet ports are both connected to the oil drain passage 19 and are respectively connected to the high-pressure passage 21 and the low-pressure passage 22 through the first check valve 4 and the second check valve 5.

[0134] A further technical solution lies in that the cooling module D includes an electromagnetic directional valve 13, a cooler 15, a stop valve 14 and a cooling oil passage 20. The electromagnetic directional valve 13 is connected in series on the low-pressure passage 22, the cooling oil passage 20 is connected in parallel with the low-pressure passage 22, the cooler 15 is arranged on the cooling oil passage 20, and the stop valve 14 is arranged on the cooling oil passage 20 and is connected in series with the cooler 15.

[0135] A further technical solution lies in that the system parameter detection module E includes a flowmeter 23, a first pressure relay 8 and a second pressure relay 9. The flowmeter 23 and the first pressure relay 8 are connected to the high-pressure passage 21 and are connected to the controller 12, and the second pressure relay 9 is connected to the low-pressure passage 22 and is connected to the controller 12.

[0136] The following further describes a variable-speed variable-displacement electro-hydraulic power source control method of the present invention in conjunction with embodiments:

[0137] In this specific embodiment, the variable-speed variable-displacement electro-hydraulic power source control method of the present invention is verified by simulation.

[0138] Set the system relief valve pressure to 4 MPa, and give a control oil pressure of 5 MPa to the bidirectional variable pump. When the system flow rate changes from 5 L / min to 10 L / min and from 10 L / min to 15 L / min, respectively, for the dual-variable power unit, fixed-speed variable-displacement power unit, and variable-speed fixed-displacement power unit using the variable-speed variable-displacement electro-hydraulic power source control method, carry out simulation verification work on the response characteristics and power input of the three, and the corresponding simulation results are respectively as Figure 4 , Figure 5 , Figure 6 and Figure 7 shown.

[0139] As Figure 4 and Figure 5 shown, when the system flow rate changes from 5 L / min to 10 L / min, the rise time of the flow rate response of the dual-variable power unit using the variable-speed variable-displacement electro-hydraulic power source control method is 38 ms, and the input power is 0.68 kW. The rise time of the flow rate response of the fixed-speed variable-displacement power unit is 57 ms, and the input power is 0.73 kW. The rise time of the flow rate response of the variable-speed fixed-displacement power unit is 96 ms, and the input power is 0.96 kW. Figure 4 In it, 41 is variable-speed fixed-displacement, 42 is fixed-speed variable-displacement, 43 is variable-speed variable-displacement, Figure 5 In it, 51 is variable-speed fixed-displacement, 52 is fixed-speed variable-displacement, 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.

[0140] As Figure 6 and Figure 7 shown, when the system flow rate changes from 10 L / min to 15 L / min, the rise time of the flow rate response of the dual-variable power unit using the variable-speed variable-displacement electro-hydraulic power source control method is 34 ms, and the input power is 1.19 kW. The rise time of the flow rate response of the fixed-speed variable-displacement power unit is 39 ms, and the input power is 1.21 kW. The rise time of the flow rate response of the variable-speed fixed-displacement power unit is 96 ms, and the input power is 1.57 kW. Figure 6 In it, 61 is variable-speed fixed-displacement, 62 is fixed-speed variable-displacement, 63 is variable-speed variable-displacement, Figure 7 In it, 71 is variable-speed fixed-displacement, 72 is fixed-speed variable-displacement, 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 optimization matching control method based on genetic algorithm proposed in this paper can effectively balance the dynamic response of the overall flow rate of the power unit and achieve efficient matching of the servo motor and the bidirectional variable pump.

[0141] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall 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 servo motor copper loss, 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 servo motor copper loss, 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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