A dual variable power source hydraulic system and control method for electric loader boom

Abstract

The present invention discloses a dual-variable power source hydraulic system and control method for an electric loader boom, belonging to the field of energy-saving technology for electric engineering machinery. The hydraulic system configuration is composed of a permanent magnet synchronous servo motor and an electro-hydraulic proportional variable device to form a dual-variable power source direct-drive arm hydraulic cylinder. The one-way valve realizes the oil cylinder, motor oil replenishment and flow reproduction functions according to the hydraulic cylinder working condition. The direct-acting overflow valve realizes the overflow protection of the hydraulic system. The two-position two-way electromagnetic reversing valve realizes the hydraulic cylinder pressure-maintaining function. The control method of the hydraulic system configuration is that the host computer outputs the target instruction to the dual-variable parameter optimization controller, and then the dual-variable parameter optimization controller outputs the optimal speed or displacement signal to the motor pump group, and the pressure closed loop is realized by feedback of the pressure signal by the pump outlet pressure sensor. The present invention can effectively realize the energy recovery function in configuration, and can greatly improve the energy efficiency characteristics of the power source in control method, and effectively improve the endurance time of the electric loader.

Description

Technical Field

[0001] The invention relates to the technical field of energy-saving of electric engineering machinery, and in particular to a dual-variable power source hydraulic system and a control method for an electric loader boom. Background Art

[0002] Electric loaders are engineering machinery for large load operations. Their endurance cannot meet the needs of their production operation time due to the inherent technical defects of the system configuration. As the core transmission system of the working device of the electric loader, it is particularly important to achieve high energy efficiency. The hydraulic system of the traditional electric loader is a quantitative hydraulic power source configuration, that is, a three-phase asynchronous motor drives a quantitative pump. This configuration cannot achieve accurate matching of the power source of the electric loader with the load power, and there is serious system throttling loss. At the same time, the system lacks energy recovery capabilities, which leads to the problem of serious lack of endurance of the electric loader. Therefore, achieving accurate power matching of the electric loader hydraulic system can directly affect the operation capacity of the electric loader.

[0003] In order to make up for the problems of fixed variable power source configuration and low energy utilization rate of traditional electric loaders, the present invention proposes a dual variable power source hydraulic system and a control method for an electric loader boom. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a dual-variable power source hydraulic system and control method for the boom of an electric loader, which can achieve precise power matching of the electric loader, effectively improve the endurance time of the electric loader, and improve the inherent technical defects of the hydraulic system such as low integration and poor anti-pollution ability.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A dual-variable power source hydraulic system for an electric loader boom, comprising a permanent magnet synchronous servo motor, a servo driver, a dual-variable parameter optimization controller, a pressure sensor, a boom hydraulic cylinder, an electro-hydraulic proportional variable device, an oil tank and a valve block;

[0007] The output shaft of the permanent magnet synchronous servo motor is connected to the input shaft of the electro-hydraulic proportional variable device through a coupling; a low-pressure channel, a high-pressure channel and a low-pressure oil replenishment channel are provided in the valve block; the first pressure outlet of the electro-hydraulic proportional variable device is connected to the rodless chamber of the boom hydraulic cylinder through the high-pressure channel, the second pressure outlet of the electro-hydraulic proportional variable device is connected to the rod chamber of the boom hydraulic cylinder through the low-pressure channel, and the oil drain port of the electro-hydraulic proportional variable device is connected to the oil tank; the low-pressure oil replenishment channel is connected to the oil tank; the pressure sensor is arranged on the high-pressure channel and is connected to the dual-variable parameter optimization controller; the dual-variable parameter optimization controller receives the pressure or flow target instruction given by the host computer, and outputs the displacement instruction to the electro-hydraulic proportional variable device and the speed instruction to the servo driver through the dual-variable parameter optimization control algorithm; the servo driver controls the action of the permanent magnet synchronous servo motor to realize the system pressure closed-loop control.

[0008] A further improvement of the technical solution of the present invention is that the electro-hydraulic proportional variable device is an electro-hydraulic proportional variable pump or an electro-hydraulic proportional variable motor.

[0009] A further improvement of the technical solution of the present invention is that it also includes a first one-way valve, a second one-way valve and a back-pressure one-way valve; the oil inlet of the first one-way valve is connected to the low-pressure channel, and the oil outlet is connected to the high-pressure channel; the oil inlet of the second one-way valve is connected to the low-pressure oil replenishment channel, and the oil outlet is connected to the low-pressure channel; the oil inlet of the back-pressure one-way valve is connected to the low-pressure channel, and the oil outlet is connected to the low-pressure oil replenishment channel;

[0010] The function of the first one-way valve and the second one-way valve is that when the boom hydraulic cylinder is fully retracted, the rodless chamber of the boom hydraulic cylinder no longer provides high-pressure oil to the electro-hydraulic proportional variable device. However, the electro-hydraulic proportional variable device still reverses due to inertia. In order to prevent the first pressure outlet of the electro-hydraulic proportional variable device from being sucked empty, the hydraulic system replenishes oil to the first pressure outlet of the electro-hydraulic proportional variable device through the first one-way valve and the second one-way valve. Since the rodless chamber of the boom hydraulic cylinder is in a high-pressure state under any working condition, the first one-way valve is guaranteed not to interfere with the extension or retraction of the boom hydraulic cylinder. The back pressure of the back-pressure one-way valve ensures that after the oil flows out from the second pressure outlet of the electro-hydraulic proportional variable device, the oil is preferentially supplied to the rod chamber of the boom hydraulic cylinder.

[0011] A further improvement of the technical solution of the present invention is that it also includes a first two-position two-way solenoid reversing valve and a second two-position two-way solenoid reversing valve connected to the dual-variable parameter optimization controller, which provide a pressure maintaining function for the boom hydraulic cylinder; the first two-position two-way solenoid reversing valve is arranged on the high-pressure channel and connected to the rodless chamber of the boom hydraulic cylinder; the second two-position two-way solenoid reversing valve is arranged on the low-pressure channel and connected to the rod chamber of the boom hydraulic cylinder.

[0012] A further improvement of the technical solution of the present invention is that it also includes a direct-acting overflow valve that can implement overflow protection for the hydraulic system; the oil inlet of the direct-acting overflow valve is connected to the high-pressure channel, and the oil outlet is connected to the oil tank.

[0013] A control method for a dual-variable power source hydraulic system of an electric loader boom, comprising the following contents: the power source of the hydraulic system is a dual-variable coordinated control, that is, the upper computer gives the flow or pressure target instruction to the dual-variable parameter optimization controller, and the improved NSGA-Ⅲ federated learning multi-objective optimization algorithm based on the redundant and optimal point set initialization processing strategy is used to obtain the optimal motor speed and the optimal pump displacement parameters under the working condition of the electric loader boom. Then, the dual-variable parameter optimization controller outputs the motor target speed to the servo driver, and the dual-variable parameter optimization controller controls the swash plate swing angle of the electro-hydraulic proportional variable device, so as to achieve the system target displacement requirement;

[0014] The pressure sensor feeds back the pressure signal to the dual-variable parameter optimization controller to realize closed-loop control of the system pressure; the motor pump group adopts a closed pump control configuration, and the inlet and outlet oil ports of the electro-hydraulic proportional variable device are connected to the two chambers of the boom hydraulic cylinder through the valve block, and work together with the permanent magnet synchronous servo motor to control the extension and retraction of the boom hydraulic cylinder. When the boom hydraulic cylinder is in the retracted condition, this condition belongs to the energy recovery condition. The hydraulic system can realize the energy recovery conversion of gravitational potential energy-hydraulic energy-electric energy. At this stage, the electro-hydraulic proportional variable device works in the motor condition, and the permanent magnet synchronous servo motor works in the generator condition.

[0015] An overall logic control method for a dual-variable power source hydraulic system of an electric loader boom includes the following contents: when an operator issues a target command using a boom handle, a dual-variable parameter optimization controller receives a system target pressure or flow command, and the dual-variable parameter optimization controller iteratively calculates the optimal speed of a permanent magnet synchronous servo motor and the optimal displacement of an electro-hydraulic proportional variable device in this working condition of the system through an improved NSGA-Ⅲ federated learning multi-objective optimization algorithm based on a redundant and optimal point set initialization processing strategy, and outputs a speed command to a servo driver, so that the servo driver controls the permanent magnet synchronous servo motor to run at the optimal speed, and the dual-variable parameter optimization controller simultaneously controls the opening of a pilot proportional control valve inside the electro-hydraulic proportional variable device, thereby controlling the action of a variable displacement hydraulic cylinder of the electro-hydraulic proportional variable device, and finally drives the variable displacement mechanism to swing to an angle so that the electro-hydraulic proportional variable device reaches an optimal displacement value;

[0016] The dual variable parameter optimization controller will perform classification control and judgment of working conditions in real time according to the boom handle operation instructions:

[0017] When the boom handle target speed v=0, it means that the boom hydraulic cylinder is in the instantaneous stop and pressure maintenance condition, so the dual variable parameter optimization controller controls the motor pump group to stop working, the first two-position two-way solenoid reversing valve and the second two-position two-way solenoid reversing valve are powered off and closed, and the first check valve is automatically turned on by the pressure difference characteristic of the hydraulic system to replenish oil for the electro-hydraulic proportional variable device, and finally the boom hydraulic cylinder achieves instantaneous stop and pressure maintenance;

[0018] When the boom handle target speed v>0, it means that the boom hydraulic cylinder is in the extension working condition at this time, so the dual variable parameter optimization controller controls the first two-position two-way solenoid reversing valve and the second two-position two-way solenoid reversing valve to be energized, and the second one-way valve is automatically turned on due to the asymmetric cylinder characteristics of the hydraulic system to replenish oil for the electro-hydraulic proportional variable device, and finally the boom hydraulic cylinder realizes the extension command;

[0019] When the target speed v of the boom handle is less than 0, it indicates that the boom hydraulic cylinder is in the retracted condition at this time, and thus the dual-variable parameter optimization controller controls the first two-position two-way solenoid reversing valve and the second two-position two-way solenoid reversing valve to be energized, and the back-pressure check valve is automatically turned on due to the pressure characteristics of the hydraulic system, and the excess oil in the system is discharged back to the oil tank through the low-pressure oil replenishing channel of the valve block, and finally the boom hydraulic cylinder realizes the retraction command.

[0020] A dual variable parameter optimization control method for a dual variable power source hydraulic system of an electric loader boom comprises the following contents: an improved NSGA-III federated learning multi-objective optimization algorithm based on a redundant and optimal point set initialization processing strategy, and adding power unit energy efficiency and response characteristics as constraints to obtain an optimal speed displacement combination under the optimal energy efficiency characteristics of a permanent magnet synchronous servo motor and an electro-hydraulic proportional variable device; the initial input parameters of the hydraulic system are the initial displacement V of a variable pump, the speed n of a servo motor, a system target pressure p and a system target flow q, and the optimal point set initialization processing is performed with the power unit energy efficiency characteristics and response characteristics as constraints, so as to generate a reference point after performing non-dominated sorting on the parent generation, and then select the first generation parent generation population for crossover mutation to generate a new offspring generation, and perform fast non-dominated sorting and population evaluation to select dominant individuals to form a new population, and iterate repeatedly until a Pareto optimal solution is output.

[0021] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is:

[0022] 1. The present invention adopts a dual-variable power source configuration to replace the traditional quantitative power source configuration. According to different working conditions of the actuator, a reasonable control strategy can be used to adapt to changes in the working environment with higher energy efficiency characteristics and dynamic response characteristics, thereby improving the overall energy efficiency in terms of power matching, while reducing system heating and flow loss. In addition, the hydraulic configuration is applied to the hydraulic system of the working device of the electric loader to realize the energy recovery function, converting the gravitational potential energy into hydraulic energy and then into electrical energy.

[0023] 2. The control method of the present invention adopts an improved NSGA-Ⅲ federated learning multi-objective optimization algorithm based on redundant and optimal point set initialization processing strategy, and adds the power unit energy efficiency and response characteristics as constraints to obtain the optimal speed and displacement combination under the optimal energy efficiency characteristics of the permanent magnet synchronous servo motor and the electro-hydraulic proportional variable pump. Compared with other control strategies, this method has higher optimization ability and optimization accuracy while ensuring dynamic response characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 It is a hydraulic principle diagram of a dual variable power source hydraulic system of an electric loader boom provided in an embodiment of the present invention;

[0026] Figure 2is an overall logic control flow chart in an embodiment of the present invention;

[0027] Figure 3 is a dual variable parameter optimization logic control flow chart in an embodiment of the present invention;

[0028] Among them, 1. Coupling; 2. Permanent magnet synchronous servo motor; 3. Servo drive; 4. Dual variable parameter optimization controller; 5. Direct-acting overflow valve; 6. Pressure sensor; 7-1. First two-position two-way solenoid reversing valve; 7-2. Second two-position two-way solenoid reversing valve; 8. Boom hydraulic cylinder; 9-1. First one-way valve; 9-2. Second one-way valve; 10. Back pressure one-way valve; 11. Electro-hydraulic proportional variable device; 11-1. First pressure outlet; 11-2. Second pressure outlet; 11-3. Oil drain port; 12. Oil tank; 13. Valve block; 14. Low-pressure channel; 15. High-pressure channel; 16. Low-pressure oil replenishment channel. DETAILED DESCRIPTION

[0029] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or apparatus.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0031] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "several" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0032] The present invention is further described in detail below with reference to the accompanying drawings and embodiments:

[0033] like Figure 1As shown, a dual-variable power source hydraulic system of an electric loader boom includes a coupling 1, a permanent magnet synchronous servo motor 2, a servo driver 3, a dual-variable parameter optimization controller 4, a direct-acting relief valve 5, a pressure sensor 6, a first two-position two-way electromagnetic reversing valve 7-1, a second two-position two-way electromagnetic reversing valve 7-2, a boom hydraulic cylinder 8, a first one-way valve 9-1, a second one-way valve 9-2, a back pressure one-way valve 10, an electro-hydraulic proportional variable device 11, an oil tank 12, and a valve block 13.

[0034] The dual variable parameter optimization controller 4 receives the pressure or flow target instruction given by the host computer, and outputs the displacement instruction to the electro-hydraulic proportional variable device 11 and the speed instruction to the servo driver 3 through the dual variable parameter optimization control algorithm; the servo driver 3 controls the action of the permanent magnet synchronous servo motor 2; the output shaft of the permanent magnet synchronous servo motor 2 is connected to the input shaft of the electro-hydraulic proportional variable device 11 through the coupling 1; the valve block 13 is provided with a high pressure channel 15, a low pressure channel 14 and a low pressure oil replenishment channel 16, and the electro-hydraulic proportional variable device 11 is connected to the output shaft of the permanent magnet synchronous servo motor 2 ... electro-hydraulic proportional variable device 11 is connected to the output shaft of the permanent magnet synchronous servo motor 2 The first pressure outlet 11-1 of the electro-hydraulic proportional variable device 11 is connected to the rodless chamber of the boom hydraulic cylinder 8 through the high-pressure channel 15 of the valve block 13, the second pressure outlet 11-2 of the electro-hydraulic proportional variable device 11 is connected to the rod chamber of the boom hydraulic cylinder 8 through the low-pressure channel 14 of the valve block 13, and the oil drain port 11-3 of the electro-hydraulic proportional variable device 11 is connected to the oil tank 12; the pressure sensor 6 is arranged on the high-pressure channel 15 of the valve block 13 and is connected to the dual-variable parameter optimization controller 4, thereby realizing system pressure closed-loop control.

[0035] Furthermore, the electro-hydraulic proportional variable device 11 is an electro-hydraulic proportional variable pump or an electro-hydraulic proportional variable motor.

[0036] Furthermore, the low-pressure oil replenishment channel 16 of the valve block 13 is connected to the oil tank 12; the oil inlet of the second one-way valve 9-2 is connected to the low-pressure oil replenishment channel 16 of the valve block 13, and the oil outlet of the second one-way valve 9-2 is connected to the low-pressure channel 14 of the valve block 13; the oil inlet of the one-way valve 10 is connected to the low-pressure channel 14 of the valve block 13, and the oil outlet of the back-pressure one-way valve 10 is connected to the low-pressure oil replenishment channel 16 of the valve block 13; the oil inlet of the first one-way valve 9-1 is connected to the low-pressure channel 14 of the valve block 13, and the oil outlet of the second one-way valve 9-2 is connected to the high-pressure channel 15 of the valve block 13.

[0037] The function of the first one-way valve 9-1 and the second one-way valve 9-2 is that when the boom hydraulic cylinder 8 is fully retracted, the rodless chamber of the boom hydraulic cylinder 8 no longer supplies high-pressure oil to the electro-hydraulic proportional variable device 11. However, the electro-hydraulic proportional variable device 11 still reverses due to inertia. In order to prevent the first pressure outlet 11-1 of the electro-hydraulic proportional variable device 11 from being sucked empty, the hydraulic system replenishes oil to the first pressure outlet 11-1 of the electro-hydraulic proportional variable device 11 through the first one-way valve 9-1 and the second one-way valve 9-2. Since the rodless chamber of the boom hydraulic cylinder 8 is in a high-pressure state under any working condition, the first one-way valve 9-1 is guaranteed not to interfere with the extension or retraction of the boom hydraulic cylinder 8. The back pressure of the back pressure one-way valve 10 ensures that after the oil flows out from the second pressure outlet 11-2 of the electro-hydraulic proportional variable device 11, the oil is preferentially supplied to the rod chamber of the boom hydraulic cylinder 8.

[0038] Furthermore, the first two-position two-way solenoid reversing valve 7-1 is arranged on the high-pressure channel 15 of the valve block 13 and is connected to the rodless chamber of the boom hydraulic cylinder 8. The second two-position two-way solenoid reversing valve 7-2 is arranged on the low-pressure channel 14 of the valve block 13 and is connected to the rod chamber of the boom hydraulic cylinder 8. The first two-position two-way solenoid reversing valve 7-1 and the second two-position two-way solenoid reversing valve 7-2 provide a pressure maintaining function for the boom hydraulic cylinder 8.

[0039] Furthermore, the direct-acting relief valve 5 can implement overflow protection for the hydraulic system. The oil inlet of the direct-acting relief valve 5 is connected to the high-pressure channel 15 of the valve block 13 , and the oil outlet is connected to the oil tank 12 .

[0040] A control method for a dual-variable power source hydraulic system of an electric loader boom specifically includes the following contents: the power source of the hydraulic system is dual-variable coordinated regulation, that is, the upper computer gives the flow or pressure target instruction to the dual-variable parameter optimization controller 4 through multi-objective parameter optimization, thereby obtaining the optimal motor speed and optimal pump displacement parameters under the corresponding electric loader boom working condition, and then the dual-variable parameter optimization controller 4 outputs the motor target speed to the servo driver 3, and the dual-variable parameter optimization controller 4 controls the swash plate swing angle of the electro-hydraulic proportional variable device 11, thereby achieving the system target displacement requirement.

[0041] The pressure sensor 6 feeds back the pressure signal to the dual variable parameter optimization controller 4 to realize the closed loop control of the system pressure. The motor pump group adopts a closed pump control configuration, and the inlet and outlet of the electro-hydraulic proportional variable device 11 are connected to the two chambers of the boom hydraulic cylinder 8 through the valve block 13, and cooperates with the permanent magnet synchronous servo motor 2 to control the extension and retraction of the boom hydraulic cylinder 8.

[0042] When the boom hydraulic cylinder 8 of the hydraulic system is in the extended condition, the first pressure outlet 11-1 of the electro-hydraulic proportional variable device 11 outputs high-pressure oil. The high-pressure oil passes through the high-pressure channel 15 of the valve block 13, and then flows to the rodless chamber of the boom hydraulic cylinder 8 through the first two-position two-way solenoid reversing valve 7-1. The oil in the rod chamber of the boom hydraulic cylinder 8 passes through the low-pressure channel 14 of the valve block 13, flows through the second two-position two-way solenoid reversing valve 7-2, and finally flows into the second pressure outlet 11-2 of the electro-hydraulic proportional variable device 11. Since the volume of the rod chamber of the boom hydraulic cylinder 8 is smaller than that of the rodless chamber, the second pressure outlet 11-2 of the electro-hydraulic proportional variable device 11 will replenish oil to the low-pressure channel 14 of the valve block 13 through the second one-way valve 9-2. The replenished oil passes through the oil tank 12, flows through the low-pressure oil replenishment channel 16 of the valve block 13, and flows into the oil inlet of the second one-way valve 9-2.

[0043] When the boom hydraulic cylinder 8 of the hydraulic system is in the retracted state, this state belongs to the energy recovery state, and the system can realize the energy recovery conversion of gravitational potential energy-hydraulic energy-electric energy. At this stage, the electro-hydraulic proportional variable device 11 works in the motor state, and the permanent magnet synchronous servo motor 2 works in the generator state. The high-pressure oil flows from the rodless chamber of the boom hydraulic cylinder 8 into the high-pressure channel 15 of the valve block 13, and flows into the first pressure outlet 11-1 of the electro-hydraulic proportional variable device 11 through the first two-position two-way electromagnetic reversing valve 7-1, thereby driving the electro-hydraulic proportional variable device 11 to reverse and drive the permanent magnet synchronous servo motor 2 to reverse and generate electricity. At the same time, the oil flows out from the second pressure outlet 11-2 of the electro-hydraulic proportional variable device 11 to the low-pressure channel 14 of the valve block 13, and finally flows into the rod chamber of the boom hydraulic cylinder 8 through the second two-position two-way electromagnetic reversing valve 7-2. Since the volume of the rodless chamber of the boom hydraulic cylinder 8 is larger than the volume of the rod chamber, when the rod chamber is filled with oil, the oil flowing out of the second pressure outlet 11-2 of the electro-hydraulic proportional variable device 11 will flow into the oil inlet of the back pressure check valve 10, and finally flow into the oil tank 12 through the low-pressure oil replenishment channel 16 of the valve block 13.

[0044] When the boom hydraulic cylinder 8 is fully retracted, the rodless chamber of the boom hydraulic cylinder 8 no longer provides high-pressure oil to the electro-hydraulic proportional variable device 11. However, the electro-hydraulic proportional variable device 11 still reverses due to inertia. To prevent the first pressure outlet 11-1 of the electro-hydraulic proportional variable device 11 from being sucked empty, the system replenishes oil to the first pressure outlet 11-1 of the electro-hydraulic proportional variable device 11 through the first check valve 9-1 and the second check valve 9-2. Since the rodless chamber of the boom hydraulic cylinder 8 is in a high-pressure state under any working condition, it can be ensured that the first check valve 9-1 will not interfere with the working conditions such as the extension or retraction of the boom hydraulic cylinder 8. The back pressure of the back pressure check valve 10 ensures that after the oil flows out of the second pressure outlet 11-2 of the electro-hydraulic proportional variable device 11, the oil is preferentially supplied to the rod chamber of the boom hydraulic cylinder 8.

[0045] If the boom hydraulic cylinder 8 needs to keep the boom stopped during extension or retraction, two two-position two-way solenoid reversing valves (the first two-position two-way solenoid reversing valve 7-1 and the second two-position two-way solenoid reversing valve 7-2) are used to cut off the oil, thereby realizing the pressure maintaining function of the boom hydraulic cylinder 8.

[0046] like Figure 2 As shown, an overall logic control method of a dual-variable power source hydraulic system of an electric loader boom specifically includes the following contents:

[0047] When the operator uses the boom handle to issue a target instruction, the dual-variable parameter optimization controller 4 receives the system target pressure or flow instruction. The dual-variable parameter optimization controller 4 iteratively calculates the optimal speed of the permanent magnet synchronous servo motor 2 and the optimal displacement of the electro-hydraulic proportional variable device 11 in this working condition of the system through an improved NSGA-Ⅲ federated learning multi-objective optimization algorithm based on redundant and optimal point set initialization processing strategy, and outputs the speed instruction to the servo driver 3. The servo driver 3 thereby controls the permanent magnet synchronous servo motor 2 to operate at the optimal speed. The dual-variable parameter optimization controller 4 simultaneously controls the opening of the pilot proportional control valve inside the electro-hydraulic proportional variable device 11, and then controls the action of the variable displacement hydraulic cylinder of the electro-hydraulic proportional variable device 11, and finally pushes the variable displacement mechanism to swing to a certain angle so that the electro-hydraulic proportional variable device 11 reaches the optimal displacement value.

[0048] The dual variable parameter optimization controller 4 will perform classification control and judgment of working conditions according to the boom handle operation instructions in real time:

[0049] When the boom handle target speed v=0, it indicates that the boom hydraulic cylinder 8 is in the instantaneous stop and pressure maintenance working condition, so the dual variable parameter optimization controller 4 controls the motor pump group to stop working, the first two-position two-way electromagnetic reversing valve 7-1 and the second two-position two-way electromagnetic reversing valve 7-2 are powered off and closed, and the first one-way valve 9-1 is automatically turned on by the pressure difference characteristic of the hydraulic system to replenish oil for the electro-hydraulic proportional variable device 11, and finally the boom hydraulic cylinder 8 achieves instantaneous stop and pressure maintenance;

[0050] When the boom handle target speed v>0, it indicates that the boom hydraulic cylinder 8 is in the extension working condition at this time, so the dual variable parameter optimization controller 4 controls the first two-position two-way electromagnetic reversing valve 7-1 and the second two-position two-way electromagnetic reversing valve 7-2 to be energized, and the second one-way valve 9-2 is automatically turned on due to the asymmetric cylinder characteristics of the hydraulic system, and the electro-hydraulic proportional variable device 11 is replenished with oil, and finally the boom hydraulic cylinder 8 realizes the extension command;

[0051] When the target speed v of the boom handle is less than 0, it indicates that the boom hydraulic cylinder 8 is in the retracted condition at this time, and thus the dual-variable parameter optimization controller 4 controls the first two-position two-way solenoid reversing valve 7-1 and the second two-position two-way solenoid reversing valve 7-2 to be energized, and the back-pressure check valve 10 is automatically turned on due to the pressure characteristics of the hydraulic system, and the excess oil in the system is discharged back to the oil tank 12 through the valve block 13, and finally the boom hydraulic cylinder 8 realizes the retraction command.

[0052] like Figure 3 As shown, a dual variable parameter optimization control method for a dual variable power source hydraulic system of an electric loader boom specifically includes the following contents:

[0053] An improved NSGA-Ⅲ federated learning multi-objective optimization algorithm based on the redundant and optimal point set initialization processing strategy is used, and the energy efficiency and response characteristics of the power unit are added as constraints to obtain the optimal speed and displacement combination under the optimal energy efficiency characteristics of the permanent magnet synchronous servo motor 2 and the electro-hydraulic proportional variable device 11;

[0054] The initial input parameters of the hydraulic system are the initial displacement V of the variable pump, the speed n of the servo motor, the system target pressure p and the system target flow q. The energy efficiency characteristics and response characteristics of the power unit are used as constraints to initialize the optimal point set, so as to generate a reference point after non-dominated sorting of the parent generation. Subsequently, the first generation parent population is cross-mutated to generate a new offspring, and a fast non-dominated sorting and population evaluation are performed to select dominant individuals to form a new population. This is repeated iteratively until the Pareto optimal solution is output.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dual variable power source hydraulic system for an electric loader boom, characterized in that: It comprises a permanent magnet synchronous servo motor (2), a servo driver (3), a dual variable parameter optimization controller (4), a pressure sensor (6), a boom hydraulic cylinder (8), an electro-hydraulic proportional variable device (11), an oil tank (12) and a valve block (13); The output shaft of the permanent magnet synchronous servo motor (2) is connected to the input shaft of the electro-hydraulic proportional variable device (11) via a coupling (1); a low-pressure channel (14), a high-pressure channel (15) and a low-pressure oil replenishment channel (16) are provided in the valve block (13); a first pressure outlet (11-1) of the electro-hydraulic proportional variable device (11) is connected to the rodless chamber of the boom hydraulic cylinder (8) via the high-pressure channel (15); a second pressure outlet (11-2) of the electro-hydraulic proportional variable device (11) is connected to the rod chamber of the boom hydraulic cylinder (8) via the low-pressure channel (14); and the electro-hydraulic proportional variable device (11) The oil drain port (11-3) is connected to the oil tank (12); the low-pressure oil replenishment channel (16) is connected to the oil tank (12); the pressure sensor (6) is arranged on the high-pressure channel (15) and is connected to the dual-variable parameter optimization controller (4); the dual-variable parameter optimization controller (4) receives a pressure or flow target instruction from a host computer, and outputs a displacement instruction to the electro-hydraulic proportional variable device (11) and a speed instruction to the servo driver (3) through a dual-variable parameter optimization control algorithm; the servo driver (3) controls the permanent magnet synchronous servo motor (2) to operate, thereby realizing closed-loop control of system pressure.

2. A dual variable power source hydraulic system for an electric loader boom according to claim 1, characterized in that: The electro-hydraulic proportional variable device (11) is an electro-hydraulic proportional variable pump or an electro-hydraulic proportional variable motor.

3. The dual variable power source hydraulic system of an electric loader boom according to claim 1, characterized in that: It also includes a first one-way valve (9-1), a second one-way valve (9-2) and a back-pressure one-way valve (10); the oil inlet of the first one-way valve (9-1) is connected to the low-pressure channel (14), and the oil outlet is connected to the high-pressure channel (15); the oil inlet of the second one-way valve (9-2) is connected to the low-pressure oil replenishment channel (16), and the oil outlet is connected to the low-pressure channel (14); the oil inlet of the back-pressure one-way valve (10) is connected to the low-pressure channel (14), and the oil outlet is connected to the low-pressure oil replenishment channel (16); The first one-way valve (9-1) and the second one-way valve (9-2) function to prevent the first pressure outlet (11-1) of the electro-hydraulic proportional variable device (11) from sucking air, so that when the boom hydraulic cylinder (8) is fully retracted, the rodless chamber of the boom hydraulic cylinder (8) no longer supplies high-pressure oil to the electro-hydraulic proportional variable device (11). However, the electro-hydraulic proportional variable device (11) still reverses due to inertia. To prevent the first pressure outlet (11-1) of the electro-hydraulic proportional variable device (11) from being sucked air, the hydraulic system supplies high-pressure oil to the first one-way valve (9-1) and the second one-way valve (9-2). The first pressure outlet (11-1) of the electro-hydraulic proportional variable device (11) is replenished with oil; since the rodless chamber of the boom hydraulic cylinder (8) is in a high-pressure state under any working condition, it is ensured that the first check valve (9-1) will not interfere with the extension or retraction working condition of the boom hydraulic cylinder (8), and the back pressure of the back pressure check valve (10) ensures that after the oil flows out of the second pressure outlet (11-2) of the electro-hydraulic proportional variable device (11), the oil is preferentially supplied to the rod chamber of the boom hydraulic cylinder (8).

4. A dual variable power source hydraulic system for an electric loader boom according to claim 1, characterized in that: It also includes a first two-position two-way electromagnetic reversing valve (7-1) and a second two-position two-way electromagnetic reversing valve (7-2), both of which are connected to the dual-variable parameter optimization controller (4) and provide a pressure-maintaining function for the boom hydraulic cylinder (8); the first two-position two-way electromagnetic reversing valve (7-1) is arranged on the high-pressure channel (15) and is connected to the rodless chamber of the boom hydraulic cylinder (8); the second two-position two-way electromagnetic reversing valve (7-2) is arranged on the low-pressure channel (14) and is connected to the rod chamber of the boom hydraulic cylinder (8).

5. The dual variable power source hydraulic system of an electric loader boom according to claim 1, characterized in that: It also includes a direct-acting overflow valve (5) capable of implementing overflow protection for the hydraulic system; the oil inlet of the direct-acting overflow valve (5) is connected to the high-pressure duct (15), and the oil outlet is connected to the oil tank (12).

6. A control method for a dual-variable power source hydraulic system of an electric loader boom, using the dual-variable power source hydraulic system of an electric loader boom as claimed in any one of claims 1 to 5, characterized in that: Includes the following: The power source of the hydraulic system is a dual variable coordinated control, that is, the upper computer gives the flow or pressure target instruction to the dual variable parameter optimization controller (4), and the optimal motor speed and optimal pump displacement parameters corresponding to the working condition of the electric loader boom are obtained through the improved NSGA-Ⅲ federated learning multi-objective optimization algorithm based on the redundant and optimal point set initialization processing strategy. Then, the dual variable parameter optimization controller (4) outputs the motor target speed to the servo driver (3), and the dual variable parameter optimization controller (4) controls the swash plate swing angle of the electro-hydraulic proportional variable device (11), so as to achieve the system target displacement requirement; The pressure sensor (6) feeds back a pressure signal to the dual variable parameter optimization controller (4) to realize closed-loop control of the system pressure. The motor pump group adopts a closed pump control configuration. The inlet and outlet oil ports of the electro-hydraulic proportional variable device (11) are connected to the two chambers of the boom hydraulic cylinder (8) through the valve block (13), and cooperate with the permanent magnet synchronous servo motor (2) to control the extension and retraction of the boom hydraulic cylinder (8). When the boom hydraulic cylinder (8) is in a retracted working condition, this working condition belongs to an energy recovery working condition. The hydraulic system can realize energy recovery conversion of gravitational potential energy-hydraulic energy-electric energy. At this stage, the electro-hydraulic proportional variable device (11) works in a motor working condition, and the permanent magnet synchronous servo motor (2) works in a generator working condition.

7. An overall logic control method of a dual-variable power source hydraulic system of an electric loader boom, using the dual-variable power source hydraulic system of an electric loader boom as claimed in any one of claims 1 to 5, characterized in that: Includes the following: When the operator issues a target command using the boom handle, the dual variable parameter optimization controller (4) receives the system target pressure or flow command. The dual variable parameter optimization controller (4) iteratively calculates the optimal speed of the permanent magnet synchronous servo motor (2) and the optimal displacement of the electro-hydraulic proportional variable device (11) in this working condition of the system through an improved NSGA-Ⅲ federated learning multi-objective optimization algorithm based on a redundant and optimal point set initialization processing strategy, and outputs a speed command to the servo driver (3). The servo driver (3) controls the permanent magnet synchronous servo motor (2) to run at the optimal speed. The dual variable parameter optimization controller (4) simultaneously controls the opening of the pilot proportional control valve inside the electro-hydraulic proportional variable device (11), thereby controlling the action of the variable displacement hydraulic cylinder of the electro-hydraulic proportional variable device (11), and finally promotes the swing angle of the variable displacement mechanism to make the electro-hydraulic proportional variable device (11) reach the optimal displacement value; The dual variable parameter optimization controller (4) will perform classification control and judgment of the working conditions in real time according to the boom handle operation instructions: When the boom handle target speed v=0, it indicates that the boom hydraulic cylinder (8) is in a momentary stop and pressure maintenance condition, so the dual variable parameter optimization controller (4) controls the motor pump group to stop working, the first two-position two-way electromagnetic reversing valve (7-1) and the second two-position two-way electromagnetic reversing valve (7-2) are powered off and closed, and the first check valve (9-1) is automatically turned on by the pressure difference characteristic of the hydraulic system to replenish oil for the electro-hydraulic proportional variable device (11), and finally the boom hydraulic cylinder (8) achieves momentary stop and pressure maintenance; When the boom handle target speed v>0, it indicates that the boom hydraulic cylinder (8) is in the extension working condition at this time, so the dual variable parameter optimization controller (4) controls the first two-position two-way electromagnetic reversing valve (7-1) and the second two-position two-way electromagnetic reversing valve (7-2) to be energized, and the second one-way valve (9-2) is automatically turned on due to the asymmetric cylinder characteristics of the hydraulic system, and oil is replenished to the electro-hydraulic proportional variable device (11), and finally the boom hydraulic cylinder (8) realizes the extension command; When the boom handle target speed v is less than 0, it indicates that the boom hydraulic cylinder (8) is in the retracting condition at this time, so the dual variable parameter optimization controller (4) controls the first two-position two-way electromagnetic reversing valve (7-1) and the second two-position two-way electromagnetic reversing valve (7-2) to be energized, and the back pressure check valve (10) is automatically turned on due to the pressure characteristics of the hydraulic system, and the excess oil in the system is discharged back to the oil tank (12) through the low-pressure oil replenishing channel (16) of the valve block (13), and finally the boom hydraulic cylinder (8) realizes the retracting command.

8. A dual variable parameter optimization control method for a dual variable power source hydraulic system of an electric loader boom, using the dual variable power source hydraulic system of an electric loader boom as claimed in any one of claims 1 to 4, characterized in that: Includes the following: An improved NSGA-III federated learning multi-objective optimization algorithm based on redundant and optimal point set initialization processing strategy is used, and the power unit energy efficiency and response characteristics are added as constraints to obtain the optimal speed displacement combination under the optimal energy efficiency characteristics of the permanent magnet synchronous servo motor (2) and the electro-hydraulic proportional variable device (11); the initial input parameters of the hydraulic system are the initial displacement V of the variable pump, the servo motor speed n, the system target pressure p and the system target flow q, and the power unit energy efficiency characteristics and response characteristics are used as constraints to perform optimal point set initialization processing, so as to generate reference points after non-dominated sorting of the parent generation, and then select crossover mutation of the first generation parent population to generate new offspring, and perform fast non-dominated sorting and population evaluation to select dominant individuals to form a new population, and iterate repeatedly until the Pareto optimal solution is output.

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