Closed loop control system and method for axial piston pump and pump controlled motor

Abstract

The application provides a closed-loop control system and method of an axial piston pump and a pump-controlled motor, and the closed-loop control system of the axial piston pump comprises: an instruction generation module for generating a first control instruction quantity; a displacement control module for generating a first control analog quantity according to the first control instruction quantity; a driving module for generating a first driving current according to the first control analog quantity to drive the axial piston pump to work; and a displacement detection module for detecting a first piston displacement quantity or a first swash plate angle of the axial piston pump and generating a corresponding first displacement conversion quantity; wherein the displacement control module further generates a second control analog quantity according to the first displacement conversion quantity and the first control instruction quantity, the driving module further generates a second driving current according to the second control analog quantity, and the second driving current is input into the axial piston pump to control the displacement of the axial piston pump to reach a target displacement. Thus, the displacement of the axial piston pump can be accurately controlled.

Description

Technical Field

[0001] This invention relates to the field of hydraulic component control technology, specifically to a closed-loop control system and method for an axial piston pump and a pump-controlled motor. Background Technology

[0002] In related technologies, when an axial piston pump adopts an open-loop electro-proportional displacement control method, the displacement of the axial piston pump will be affected by factors such as proportional electromagnet hysteresis, load pressure changes, and engine speed changes, thus making it impossible to accurately control the displacement of the axial piston pump. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention provides a control method for an axial piston pump, which adopts an electro-proportional displacement closed-loop control method to perform closed-loop control of the axial piston pump, thereby accurately controlling the displacement of the axial piston pump.

[0004] The technical solution adopted in this invention is as follows:

[0005] A closed-loop control system for an axial piston pump includes: a command generation module, configured to receive a user-inputted input transformation quantity and generate a first control command quantity based on the input transformation quantity, wherein the input transformation quantity is an input command transformation quantity or an input speed transformation quantity; a displacement control module, configured to receive the first control command quantity and generate a first control analog quantity based on the first control command quantity; and a drive module, configured to receive the first control analog quantity, generate a first drive current based on the first control analog quantity, and input the first drive current into the axial piston pump to drive it. The axial piston pump is operated; a displacement detection module is used to detect the first piston displacement or the first swashplate angle of the axial piston pump, and generate a corresponding first displacement change value based on the first piston displacement or the first swashplate angle; wherein, the displacement control module is further used to generate a second control analog value based on the first displacement change value and the first control command value, and the drive module is further used to receive the second control analog value, generate a second drive current based on the second control analog value, and input the second drive current into the axial piston pump to control the displacement of the axial piston pump to reach the target displacement.

[0006] In one embodiment of the present invention, the displacement control module is specifically used to: calculate a first error between the first displacement change quantity and the first control command quantity, and perform closed-loop dynamic adjustment on the first error to generate the second control analog quantity.

[0007] A closed-loop control system for a pump-controlled motor, wherein the pump-controlled motor is a fixed-displacement hydraulic motor, the inlet of which is connected to the outlet of an axial piston pump, and power transmission between the fixed-displacement hydraulic motor and the axial piston pump is achieved through an oil circuit. The closed-loop control system for the pump-controlled motor includes: a closed-loop control system for the axial piston pump; a speed detection module, which detects a first speed of the pump-controlled motor and generates a feedback speed change quantity based on the first speed; wherein a command generation module receives the feedback speed change quantity and generates a second control command quantity based on the input command change quantity and the feedback speed change quantity; a displacement control module receives the second control command quantity and generates a third control analog quantity based on the second control command quantity; and a drive module receives the third control analog quantity, generates a third drive current based on the third control analog quantity, and inputs the third drive current into the axial piston pump to adjust the displacement of the axial piston pump, wherein the axial piston pump drives the pump-controlled motor to operate at a target speed.

[0008] In one embodiment of the present invention, the closed-loop control system of the pump-controlled motor further includes: an oil pressure detection module, which is used to detect the inlet oil pressure and outlet oil pressure of the pump-controlled motor, calculate a first pressure difference between the inlet oil pressure and the outlet oil pressure, and generate a pressure difference transformation quantity based on the first pressure difference; wherein, the command generation module is further used to receive the pressure difference transformation quantity, and generate a third control command quantity based on the input speed transformation quantity, the feedback speed transformation quantity, and the pressure difference transformation quantity; the displacement control module is further used to receive the third control command quantity, and generate a fourth control analog quantity based on the third control command quantity; the drive module is further used to receive the fourth control analog quantity, generate a fourth drive current based on the fourth control analog quantity, and input the fourth drive current into the axial piston pump to adjust the displacement of the axial piston pump, wherein the axial piston pump drives the pump-controlled motor to operate at a target power.

[0009] In one embodiment of the present invention, the instruction generation module is specifically used to: calculate a second error between the input instruction transformation amount and the feedback speed transformation amount, and perform closed-loop dynamic adjustment on the second error to generate the second control instruction amount.

[0010] In one embodiment of the present invention, the instruction generation module is specifically used to: calculate the equivalent power of the pump-controlled motor using an equivalent power algorithm based on the feedback speed change and the pressure difference change; correct the rated power setting of the engine using a power correction algorithm based on the input speed change to obtain a corresponding corrected power; calculate a third error between the equivalent power and the corrected power, perform closed-loop dynamic adjustment on the third error, and generate the third control instruction quantity based on the adjustment result.

[0011] A closed-loop control method for an axial piston pump includes the following steps: receiving an input transformation quantity input by a user, and generating a first control command quantity based on the input transformation quantity, wherein the input transformation quantity is an input command transformation quantity or an input speed transformation quantity; receiving the first control command quantity, and generating a first control analog quantity based on the first control command quantity; receiving the first control analog quantity, and generating a first drive current based on the first control analog quantity, and inputting the first drive current into the axial piston pump to drive the axial piston pump to operate; detecting a first piston displacement or a first swashplate angle of the axial piston pump, and generating a corresponding first displacement transformation quantity based on the first piston displacement or the first swashplate angle; generating a second control analog quantity based on the first displacement transformation quantity and the first control command quantity, receiving the second control analog quantity, and generating a second drive current based on the second control analog quantity, and inputting the second drive current into the axial piston pump to control the displacement of the axial piston pump to reach a target displacement.

[0012] A closed-loop control method for a pump-controlled motor, wherein the pump-controlled motor is a fixed-displacement hydraulic motor, the inlet of which is connected to the outlet of an axial piston pump, and power transmission between the fixed-displacement hydraulic motor and the axial piston pump is achieved through an oil circuit. The closed-loop control method for the pump-controlled motor includes the following steps: receiving a user-input command transformation quantity and generating a first control command quantity based on the input command transformation quantity; receiving the first control command quantity and generating a first control analog quantity based on the first control command quantity; receiving the first control analog quantity and generating a first drive current based on the first control analog quantity; and inputting the first drive current into the axial piston pump to drive the pump. An axial piston pump operates, wherein the axial piston pump drives the pump-controlled motor to operate; a first rotational speed of the pump-controlled motor is detected, and a feedback rotational speed change is generated based on the first rotational speed; the feedback rotational speed change is received, and a second control command is generated based on the input command change and the feedback rotational speed change; the second control command is received, and a third control analog quantity is generated based on the second control command; the third control analog quantity is received, and a third drive current is generated based on the third control analog quantity; and the third drive current is input to the axial piston pump to adjust the displacement of the axial piston pump, wherein the axial piston pump drives the pump-controlled motor to operate at a target rotational speed.

[0013] The beneficial effects of this invention are:

[0014] (1) The present invention uses an electro-proportional displacement closed-loop control method to perform closed-loop control on the axial piston pump, which can accurately control the displacement of the axial piston pump.

[0015] (2) By performing closed-loop control on the pump-controlled motor, the present invention can accurately perform constant speed or constant power adaptive control on the pump-controlled motor. Attached Figure Description

[0016] Figure 1 This is a block diagram of the closed-loop control system of the axial piston pump according to an embodiment of the present invention;

[0017] Figure 2 This is a schematic diagram of the control logic of the current control unit according to an embodiment of the present invention;

[0018] Figure 3 This is a schematic diagram of the control logic of a power amplifier unit according to an embodiment of the present invention;

[0019] Figure 4 This is a logic diagram of a control method combining PID control and feedforward compensation according to an embodiment of the present invention;

[0020] Figure 5This is a schematic diagram of the control method of Active Disturbance Rejection Control (ADRC) according to an embodiment of the present invention;

[0021] Figure 6 This is a block diagram of a closed-loop control system for a pump-controlled motor according to an embodiment of the present invention.

[0022] Figure 7 This is a block diagram of a closed-loop control system for a pump-controlled motor according to an embodiment of the present invention.

[0023] Figure 8 This is a schematic diagram of the control logic of an instruction generation module according to an embodiment of the present invention;

[0024] Figure 9 This is a flowchart of a closed-loop control method for an axial piston pump according to an embodiment of the present invention;

[0025] Figure 10 This is a flowchart of a closed-loop control method for a pump-controlled motor according to an embodiment of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Figure 1 This is a block diagram of a closed-loop control system for an axial piston pump according to an embodiment of the present invention.

[0028] like Figure 1 As shown, the closed-loop control system 10 of the axial piston pump in this embodiment of the invention may include: a command generation module 100, a displacement control module 200, a drive module 300, and a displacement detection module 400.

[0029] The system includes the following components: Command generation module 100 receives user-inputted input transformation quantities and generates a first control command quantity based on these quantities, wherein the input transformation quantity is either an input command transformation quantity or an input speed transformation quantity; Displacement control module 200 receives the first control command quantity and generates a first control analog quantity based on these quantities; Drive module 300 receives the first control analog quantity, generates a first drive current based on these quantities, and inputs the first drive current into the axial piston pump to drive it; Displacement detection module 400 detects the first piston displacement or the first swashplate angle of the axial piston pump and generates a corresponding first displacement transformation quantity based on these quantities; Displacement control module 200 further generates a second control analog quantity based on the first displacement transformation quantity and the first control command quantity; Drive module 300 further receives the second control analog quantity, generates a second drive current based on these quantities, and inputs the second drive current into the axial piston pump to control its displacement to reach the target displacement.

[0030] Specifically, such as Figure 1 As shown, one possible implementation involves inputting a dimensionless speed conversion quantity. Specifically, the user can control the engine speed via the accelerator pedal. The engine speed sensor can collect this speed and convert it into a corresponding analog input speed quantity (voltage / current). This analog input speed quantity is then input to the speed conversion module, which converts it into a dimensionless input speed conversion quantity. Another possible implementation involves inputting a dimensionless command conversion quantity. Specifically, the user can directly input an analog command quantity (voltage / current, for example, via a mobile terminal) to the input conversion module. In this case, the input conversion module can convert the analog command quantity into a dimensionless input command conversion quantity.

[0031] The instruction generation module 100 generates a corresponding first control instruction quantity based on the input transformation quantity (which can be an input instruction transformation quantity or an input speed transformation quantity), and inputs the first control instruction quantity into the displacement control module 200. The displacement control module 200 generates a dimensionless first control analog quantity based on the first control instruction, and inputs the first control analog quantity into the drive module 300. At this time, the drive module 300 can generate a first drive current based on the first control analog quantity.

[0032] Specifically, such as Figure 1 As shown, the drive module 300 may include a current control unit 310 and a power amplifier unit 320.

[0033] First, the current control unit 310 receives a first control analog quantity and generates a first control current based on the first control analog quantity using the following formula:

[0034]

[0035] Among them, V in V is the first control analog quantity; out The first control current output by the current control unit 310; V min Set the trigger dead zone to the minimum value of the first control current output; V max Limit the amplitude of the first control current output, thus limiting the maximum operating current of the proportional electromagnet; V0 is V min The activation point trigger value is set to avoid triggering V due to minor changes in the input signal. min .

[0036] In other words, such as Figure 2 As shown, the first control analog quantity of the input current control unit 310 is processed sequentially through current dead zone trigger setting, control current range setting and control current algorithm, and can output the first control current.

[0037] Next, the first control current is input to the power amplifier unit 320. The power amplifier unit 320 receives the first control current and generates the first drive current according to the following formula:

[0038]

[0039] Where I is the first drive current, I c The rated current set in the rated current setting of the proportional valve, V out The first control current output by the current control unit 310, D A D is the chatter amplitude value set in the proportional valve chatter parameter settings. f This refers to the chatter frequency set in the proportional valve chatter parameter settings.

[0040] In other words, such as Figure 3 As shown, the rated current I in the power amplifier unit 320 can be set separately. c (i.e., rated drive current setting), flutter amplitude D A and flutter frequency D f (i.e., proportional valve chatter parameter settings) and PWM pulse width modulation parameter settings, and set the rated current I c Flutter amplitude D A Flutter frequency D f and the first control current V out (That is, the control current) is used to perform power amplifier calculations through formula (2) to generate the first drive current I.

[0041] Then, the first drive current can be input into the axial piston pump to drive the axial piston pump to work. That is, the left drive current is output to the left proportional electromagnet through the left electromagnet drive circuit module, and the right drive current is output to the right proportional electromagnet through the right electromagnet drive circuit module.

[0042] It is understandable that if the first drive current is generated into the axial piston pump in the above manner to drive the axial piston pump to work, the displacement of the axial piston pump will be affected by factors such as the proportional electromagnet hysteresis, load pressure changes, and engine speed changes, thus making it impossible to accurately control the displacement of the axial piston pump.

[0043] Therefore, in this embodiment of the invention, after the axial piston pump is driven to work in the above manner, the first piston displacement or the first swashplate angle of the axial piston pump can be detected by the displacement detection module 400, and a corresponding first displacement change amount can be generated according to the first piston displacement or the first swashplate angle.

[0044] Specifically, such as Figure 1 As shown, the displacement detection module 400 may include a displacement detection unit 410 and a displacement conversion unit 420.

[0045] First, the displacement detection unit 410 can detect the first piston displacement or the first swashplate angle of the axial piston pump, generate a first displacement analog quantity (voltage / current) based on the first piston displacement or the first swashplate angle, and input the first displacement analog quantity into the displacement conversion unit 420.

[0046] Secondly, the first displacement conversion value can be generated by the displacement conversion unit 420 based on the first displacement analog value using the following formula:

[0047]

[0048] Among them, U in U is the input analog quantity. out For example, if the input analog quantity is the first displacement analog quantity, the output transformation quantity is the first displacement transformation quantity, U max For U in The maximum value, i.e., the input range, such as U max =10V or U max =20mA. Where, K i and C i Let U be two constants, such that the output transformation quantity U out It satisfies the set linearized linear function. For example, suppose the input analog quantity is U. in1 The corresponding output transformation quantity is U. out1 The input analog quantity is U in2 The corresponding output transformation quantity is U.out2 ,but

[0049]

[0050]

[0051] Finally, the displacement conversion unit 420 inputs the generated first displacement conversion value into the displacement control module 200. At this time, the displacement control module 200 can generate a second control analog value based on the first displacement conversion value and the first control command value.

[0052] Specifically, in one embodiment of the present invention, the displacement control module 200 is specifically used to: calculate the first error between the first displacement change quantity and the first control command quantity, and perform closed-loop dynamic adjustment on the first error to generate a second control analog quantity.

[0053] Specifically, such as Figure 4 As shown, the displacement control module 200 can use a control method combining PID control and feedforward compensation to generate a second control analog quantity based on the first displacement change quantity and the first control command quantity. Specifically, the first error e(t) between the first displacement change quantity and the first control command quantity can be calculated first, and then the first error e(t) can be adjusted by PID to generate the second control analog quantity.

[0054] The mathematical expression for the algorithm used by the displacement control module 200 is as follows:

[0055]

[0056] Among them, K p For the ratio -P; K p / T i s is the integral -I; K p T d s / (Ns+1) is the differential -D; K is the feedforward -K.

[0057] As another possible implementation, such as Figure 5 As shown, the displacement control module 200 can also use an active disturbance rejection control (ADRC) mode to generate a second control analog quantity based on the first displacement change quantity and the first control command quantity. Specifically, the first control command quantity can be input to the tracking differentiator TD, and the first displacement change quantity can be input to the extended state observer ESO. The errors between the output value of the tracking differentiator TD and the output value of the extended state observer ESO, namely errors e1 and e2, are calculated. Then, errors e1 and e2 are input to the nonlinear error feedback control law NLSEF to obtain the second control analog quantity.

[0058] Furthermore, the drive module 300 receives a second control analog quantity, generates a second drive current based on the second control analog quantity, and inputs the second drive current into the axial piston pump to control the displacement of the axial piston pump to achieve the target displacement. The method by which the drive module 300 generates the second drive current based on the second control analog quantity is the same as the method by which it generates the first drive current based on the first control analog quantity in the above embodiment; to avoid redundancy, it will not be described in detail here.

[0059] Therefore, the present invention uses an electro-proportional displacement closed-loop control method to perform closed-loop control of the axial piston pump, which can accurately control the displacement of the axial piston pump.

[0060] It should be noted that, as one possible implementation, the user-inputted variable is the input speed variable (dimensionless). In this mode, the control system can automatically change the displacement of the axial piston pump according to changes in engine speed, achieving adaptive adjustment of engine power. For example, changing the angle of the engine throttle pedal or changing the load condition (climbing, heavy load) will cause changes in engine speed. When the engine speed increases, the displacement of the axial piston pump is increased according to the input speed variable to fully utilize the engine power; when the engine speed decreases, the displacement of the axial piston pump is decreased according to the input speed variable to prevent the engine from stalling. As another possible implementation, the input variable can be the input command variable. In this mode, the input command variable (voltage or current) and the output displacement of the axial piston pump conform to a linear function V = kU + b, where V is the output displacement of the axial piston pump, U is the analog input command (voltage or current), and k and b represent coefficients related to the linear function curve.

[0061] In summary, the closed-loop control system of the axial piston pump according to the embodiments of the present invention receives input command change quantity or input speed change quantity input by the user through the command generation module, and generates a first control command quantity based on the input command change quantity or input speed change quantity; receives the first control command quantity through the displacement control module, and generates a first control analog quantity based on the first control command quantity; receives the first control analog quantity through the drive module, and generates a first drive current based on the first control analog quantity; and inputs the first drive current into the axial piston pump to drive the axial piston pump to work; detects the first piston displacement quantity or the first swashplate angle of the axial piston pump through the displacement detection module, and generates a corresponding first displacement change quantity based on the first piston displacement quantity or the first swashplate angle; generates a second control analog quantity through the displacement control module based on the first displacement change quantity and the first control command quantity; receives the second control analog quantity through the drive module, and generates a second drive current based on the second control analog quantity; and inputs the second drive current into the axial piston pump to control the displacement of the axial piston pump to achieve the target displacement. Therefore, by using an electro-proportional displacement closed-loop control method to control the axial piston pump, the displacement of the axial piston pump can be accurately controlled.

[0062] Corresponding to the closed-loop control system of the axial piston pump in the above embodiments, the present invention also proposes a closed-loop control system for a pump-controlled motor.

[0063] Figure 6 This is a block diagram of a closed-loop control system for a pump-controlled motor according to an embodiment of the present invention.

[0064] It should be noted that, as Figure 6 As shown, the pump-controlled motor is a fixed-displacement hydraulic motor. The oil inlet of the fixed-displacement hydraulic motor is connected to the oil outlet of the axial piston pump. Power transmission between the fixed-displacement hydraulic motor and the axial piston pump is achieved through an oil circuit.

[0065] like Figure 6 As shown, the closed-loop control system 20 for the pump-controlled motor in this embodiment of the invention may include: a closed-loop control system 10 for an axial piston pump and a speed detection module 500. The speed detection module 500 detects a first speed of the pump-controlled motor and generates a feedback speed change quantity based on the first speed. The command generation module 100 receives the feedback speed change quantity and generates a second control command quantity based on the input command change quantity and the feedback speed change quantity. The displacement control module 200 receives the second control command quantity and generates a third control analog quantity based on the second control command quantity. The drive module 300 receives the third control analog quantity, generates a third drive current based on the third control analog quantity, and inputs the third drive current into the axial piston pump to adjust the displacement of the axial piston pump. The axial piston pump drives the pump-controlled motor to operate at a target speed.

[0066] It should be noted that when the pump-controlled motor is controlled at a constant speed, the instruction generation module 100 only needs to receive the input instruction transformation quantity input by the user. Therefore, in this control mode, the input transformation quantity is the input instruction transformation quantity.

[0067] Specifically, when the closed-loop control system 10 of the axial piston pump controls the operation of the axial piston pump, power transmission can be achieved by connecting the oil circuit between the fixed displacement hydraulic motor and the axial piston pump, thereby driving the pump-controlled motor to operate. During the operation of the pump-controlled motor, the first speed of the pump-controlled motor can be detected by the speed detection module 500, and a feedback speed change amount can be generated based on the first speed.

[0068] Specifically, such as Figure 6 As shown, the speed detection module 500 may include a speed sensor 510 and a speed conversion unit 520.

[0069] First, the first speed of the pump-controlled motor can be detected by the speed sensor 510, and an analog speed value can be generated based on the first speed value, and the analog speed value can be input into the speed conversion unit 520.

[0070] Secondly, the analog speed quantity can be converted into a corresponding feedback speed conversion quantity through the speed conversion unit 520. Among them, the analog speed quantity can be converted into a corresponding speed conversion quantity (dimensionless) using formula (3).

[0071] Finally, the speed conversion unit 520 inputs the speed conversion amount to the command generation module 100. At this time, the command generation module 100 can generate a second control command amount based on the input command conversion amount and the feedback speed conversion amount.

[0072] Specifically, in one embodiment of the present invention, the instruction generation module 100 is specifically used to: calculate a second error between the input instruction change amount and the feedback speed change amount, and perform closed-loop dynamic adjustment on the second error to generate a second control instruction amount.

[0073] Specifically, the method by which the instruction generation module 100 generates the second control instruction quantity based on the input instruction change quantity and the feedback speed change quantity is similar to the method by which the displacement control module 200 generates the second control analog quantity based on the first displacement change quantity and the first control instruction quantity in the above embodiment. That is, a control method combining PID control and feedforward compensation or an active disturbance rejection (ADRC) control method can be used to generate the second control instruction quantity based on the input instruction change quantity and the feedback speed change quantity. To avoid redundancy, details will not be elaborated here.

[0074] Furthermore, the displacement control module 200 receives the second control command quantity and generates a third control analog quantity based on the second control command quantity.

[0075] Specifically, after receiving the second control command, the displacement control module 200 can convert the second control command into a dimensionless third control analog quantity.

[0076] It should be noted that, to further ensure that the axial piston pump's displacement reaches the target displacement, the displacement detection module 400 can also detect the second piston displacement or the second swashplate angle of the axial piston pump, and generate a corresponding second displacement change quantity based on the second piston displacement or the second swashplate angle, and input the second displacement change quantity into the displacement control module 200. The displacement control module 200 can generate a dimensionless third control analog quantity based on the second control command quantity and the second displacement change quantity. For specific implementation methods, please refer to the above embodiments; to avoid redundancy, they will not be detailed here.

[0077] Furthermore, the drive module 300 receives a third control analog signal, generates a third drive current based on the third control analog signal, and inputs the third drive current into the axial piston pump to adjust the displacement of the axial piston pump. The axial piston pump drives the pump-controlled motor to operate at the target speed. The method by which the drive module 300 generates the third drive current based on the third control analog signal is the same as the method by which it generates the first drive current based on the first control analog signal in the above embodiment; to avoid redundancy, it will not be described in detail here.

[0078] In this control mode, each input command analog quantity / speed analog quantity (voltage or current) can correspond to a constant output speed of a pump-controlled motor. When the command analog quantity / speed analog quantity (voltage or current) remains unchanged, the pump-controlled motor can maintain a stable and accurate constant speed, and is not affected by factors such as changes in the speed of the axial piston pump or changes in the motor load conditions.

[0079] In one embodiment of the present invention, such as Figure 7 As shown, the closed-loop control system 20 of the pump-controlled motor may include: an oil pressure detection module 600. The oil pressure detection module 600 is used to detect the inlet and outlet oil pressures of the pump-controlled motor, calculate a first pressure difference between the inlet and outlet oil pressures, and generate a pressure difference transformation quantity based on the first pressure difference. The command generation module 100 is also used to receive the pressure difference transformation quantity and generate a third control command quantity based on the input speed transformation quantity, the feedback speed transformation quantity, and the pressure difference transformation quantity. The displacement control module 200 is also used to receive the third control command quantity and generate a fourth control analog quantity based on the third control command quantity. The drive module 300 is also used to receive the fourth control analog quantity and generate a fourth drive current based on the fourth control analog quantity, and input the fourth drive current into the axial piston pump to adjust the displacement of the axial piston pump. The axial piston pump drives the pump-controlled motor to operate at a target power. This target power is matched with the engine power, realizing the motor's power adaptation control to the engine.

[0080] It should be noted that when performing constant power adaptive control on the pump-controlled motor, the instruction generation module 100 only needs to receive the input speed change amount input by the user. Therefore, in this control mode, the input change amount is the input speed change amount.

[0081] Specifically, when the closed-loop control system 10 of the axial piston pump controls the operation of the axial piston pump, power transmission can be achieved by connecting the oil circuit between the fixed displacement hydraulic motor and the axial piston pump, thereby driving the pump-controlled motor to operate. During the operation of the pump-controlled motor, in addition to detecting the first speed of the pump-controlled motor through the speed detection module 500 and generating a speed change amount based on the first speed, the oil pressure detection module 600 can also detect the oil pressure at the inlet and outlet of the pump-controlled motor, calculate the first pressure difference between the inlet and outlet oil pressures, and generate a pressure difference change amount based on the first pressure difference.

[0082] Specifically, such as Figure 7 As shown, the oil pressure detection module 600 may include an oil pressure detection sensor 610 and a differential pressure conversion unit 620.

[0083] First, the oil pressure at the inlet and outlet of the pump-controlled motor can be detected by the oil pressure detection sensor 610, and the first pressure difference between the inlet and outlet oil pressures can be calculated. The first pressure difference is then converted into an analog pressure difference quantity, and the analog pressure difference quantity is input into the pressure difference conversion unit 620.

[0084] Secondly, the differential pressure analog quantity can be converted into the corresponding differential pressure transformed quantity through the differential pressure transformation unit 620. Among them, the differential pressure analog quantity can be converted into the corresponding differential pressure transformed quantity (dimensionless) using formula (3).

[0085] Finally, the differential pressure conversion unit 620 inputs the differential pressure conversion amount to the instruction generation module 100, and simultaneously, the speed conversion unit 520 inputs the feedback speed conversion amount to the instruction generation module 100. At this time, the instruction generation module 100 can generate a third control instruction amount based on the input speed conversion amount, the feedback speed conversion amount, and the differential pressure conversion amount.

[0086] Specifically, in one embodiment of the present invention, the instruction generation module 100 is specifically used to: calculate the equivalent power of the pump-controlled motor using an equivalent power algorithm based on the feedback speed change and pressure difference change; correct the rated power setting of the engine using a power correction algorithm based on the input speed change to obtain the corresponding corrected power; calculate the third error between the equivalent power and the corrected power, perform closed-loop dynamic adjustment on the third error, and generate a third control instruction quantity based on the adjustment result.

[0087] Specifically, firstly, the input feedback speed change and pressure difference change are used to calculate the equivalent power of the pump-controlled motor according to the equivalent power algorithm. Secondly, after the input speed change is processed by the power correction algorithm, the initial rated power setting of the engine is corrected to generate the corresponding corrected power.

[0088] The equivalent power algorithm for the motor can be as follows:

[0089]

[0090] Among them, P m Indicates motor power (kW); V g Indicates motor displacement (ml / r); Δp represents the differential pressure between the motor inlet and outlet (MPa); η mh This represents the motor's mechanical efficiency; n represents the motor's rotational speed (r / min).

[0091] in,

[0092]

[0093] Where n′ represents the feedback speed change (dimensionless), ΔP′ represents the pressure change (dimensionless), K1 and C1 represent the speed change coefficients (r / min), and K2 and C2 represent the pressure change coefficients (MPa).

[0094] Combining formula (7) and formula (8), we can obtain the equivalent power of the motor:

[0095] P m =K0·(K1n′+C1)·(K2Δp′+C2) (9)

[0096] The engine power correction algorithm can be:

[0097]

[0098] Among them, P e Indicates the engine's rated speed n e Rated power (kW) at (r / min); P e 1 This represents the actual power (kW) at the actual engine speed n (r / min); m represents the interval of the piecewise function, i.e., the trigger dead zone for engine power correction; K3, C3, K4, and C4 represent the power correction coefficients.

[0099] Then, the third error between the equivalent power and the corrected power is calculated, and the third error is dynamically adjusted in a closed loop. A third control command is generated based on the adjustment result. This third control command can be generated by the power conversion unit in the command generation module 100 based on the adjustment result. Similarly, a control method combining PID control and feedforward compensation, or an active disturbance rejection (ADRC) control method, can be used to generate the third control command. Refer to the above embodiments; to avoid redundancy, details are omitted here.

[0100] Furthermore, the displacement control module 200 receives the third control command quantity and generates the fourth control analog quantity based on the third control command quantity.

[0101] It should be noted that, to further ensure that the axial piston pump's displacement reaches the target displacement, the displacement detection module 400 can also detect the third piston displacement or the third swashplate angle of the axial piston pump, and generate a corresponding third displacement change quantity based on the third piston displacement or the third swashplate angle, which is then input into the displacement control module 200. The displacement control module 200 can generate a dimensionless fourth control analog quantity based on the third control command quantity and the third displacement change quantity. For specific implementation methods, please refer to the above embodiments; to avoid redundancy, details will not be elaborated here.

[0102] Furthermore, the drive module 300 receives a fourth control analog quantity, generates a fourth drive current based on the fourth control analog quantity, and inputs the fourth drive current into the axial piston pump to adjust the displacement of the axial piston pump. The axial piston pump drives the pump-controlled motor to operate at the target power. The method by which the drive module 300 generates the fourth drive current based on the fourth control analog quantity is the same as the method by which it generates the first drive current based on the first control analog quantity in the above embodiment; to avoid redundancy, it will not be described in detail here.

[0103] The power correction is affected by changes in engine speed. In this mode, when the engine speed increases to a value greater than the rated speed, it indicates that the engine output power is greater than the set power. After the input speed change is processed by the power correction algorithm, the corrected power is made greater than the set power. The closed-loop control system of the pump-controlled motor will increase the control command, thereby increasing the drive current to the proportional displacement valve, and ultimately increasing the displacement, power, and power of the axial piston pump and the pump-controlled motor to fully utilize the engine power. Conversely, when the engine speed decreases to a value less than the rated speed, the closed-loop control system of the pump-controlled motor will decrease the displacement, power, and power of the axial piston pump and the pump-controlled motor to prevent the engine from stalling, thus achieving constant power adaptive control of the pump-controlled motor for the engine.

[0104] It should be noted that the closed-loop control system 20 for the pump-controlled motor in this embodiment of the invention, or the closed-loop control system for the axial piston pump in the above embodiment, can integrate a control card with information storage and programming functions, consisting of a digital chip or analog chip and a circuit board. The control card is equipped with external interfaces including a CAN bus interface, a PC software interface, and a signal acquisition interface. The CAN bus interface is used to output drive current from the control system to the electro-proportional displacement valve of the axial piston pump. The PC software interface is used to enable communication between the control system and the PC debugging software, set parameters for each module in the control system, and save the program. The signal acquisition interface is used to receive voltage or current from the displacement detection module 400, the engine speed sensor, the motor speed sensor, the speed sensor 510, and input analog commands.

[0105] Specifically, in one specific embodiment of the present invention, such as Figure 8 As shown, in practical applications, the instruction generation module 100 can select different control modes to generate corresponding control instruction quantities according to specific control requirements. Specifically, when it is necessary to control the displacement of the axial piston pump, control mode 1 can be selected, that is, receiving the input command change amount or the input speed change amount, and generating the corresponding first control command amount according to the input command change amount or the input speed change amount, as can be referred to in the above embodiment; when it is necessary to perform constant speed control on the pump-controlled motor, control mode 2 can be selected, that is, receiving the input command change amount, and generating the corresponding second control command amount according to the input command change amount through the first controller in the command generation module 100, as can be referred to in the above embodiment; when it is necessary to perform constant power adaptive control on the pump-controlled motor, control mode 3 can be selected, that is, receiving the input speed change amount, using the equivalent power algorithm to calculate the equivalent power of the pump-controlled motor according to the feedback speed change amount and the pressure difference change amount, using the power correction algorithm to correct the rated power setting value of the engine according to the input speed change amount to obtain the corresponding corrected power, calculating the third error of the equivalent power and the corrected power through the first controller, and performing closed-loop dynamic adjustment on the third error, and generating the third control command amount according to the adjustment result through the power conversion unit.

[0106] In summary, the closed-loop control system for the pump-controlled motor according to an embodiment of the present invention detects a first speed of the pump-controlled motor through a speed detection module and generates a feedback speed change quantity based on the first speed. It also receives the feedback speed change quantity through a command generation module and generates a second control command quantity based on the input command change quantity and the feedback speed change quantity. Furthermore, it receives the second control command quantity through a displacement control module and generates a third control analog quantity based on the second control command quantity. Finally, it receives the third control analog quantity through a drive module and generates a third drive current based on the third control analog quantity. The third drive current is then input to the axial piston pump to adjust the displacement of the axial piston pump, wherein the axial piston pump drives the pump-controlled motor to operate at the target speed. Therefore, by performing closed-loop control on the pump-controlled motor, accurate constant speed control of the pump-controlled motor can be achieved.

[0107] Corresponding to the closed-loop control system of the axial piston pump in the above embodiments, the present invention also proposes a closed-loop control method for the axial piston pump.

[0108] like Figure 9 As shown, the closed-loop control method for the axial piston pump in this embodiment of the invention may include the following steps:

[0109] S601: Receive the input transformation quantity input by the user, and generate a first control command quantity based on the input transformation quantity. The input transformation quantity can be an input command transformation quantity or an input speed transformation quantity.

[0110] S602, receive the first control command quantity, and generate the first control analog quantity according to the first control command quantity.

[0111] S603 receives a first control analog quantity, generates a first drive current based on the first control analog quantity, and inputs the first drive current into the axial piston pump to drive the axial piston pump to work.

[0112] S604 detects the first piston displacement or the first swashplate angle of the axial piston pump and generates a corresponding first displacement change based on the piston displacement or the first swashplate angle.

[0113] S605 generates a second control analog quantity based on the first displacement change quantity and the first control command quantity.

[0114] In one embodiment of the present invention, generating a second control analog quantity based on a first displacement change quantity and a first control command quantity may include: calculating a first error between the first displacement change quantity and the first control command quantity, and performing closed-loop dynamic adjustment on the first error to generate the second control analog quantity.

[0115] S606 receives a second control analog quantity, generates a second drive current based on the second control analog quantity, and inputs the second drive current into the axial piston pump to control the displacement of the axial piston pump to achieve the target displacement.

[0116] It should be noted that a more specific embodiment of the closed-loop control method for the axial piston pump of the present invention can be found in the embodiment of the closed-loop control system for the axial piston pump described above. To avoid redundancy, it will not be described in detail here.

[0117] According to an embodiment of the present invention, a closed-loop control method for an axial piston pump receives a user-inputted input transformation quantity, which is either an input command transformation quantity or an input speed transformation quantity. A first control command quantity is generated based on this quantity. The method also receives the first control command quantity and generates a first control analog quantity based on it. Furthermore, the method receives the first control analog quantity and generates a first drive current based on it. The first drive current is then input into the axial piston pump to drive the pump. The method also detects a first piston displacement or a first swashplate angle and generates a corresponding first displacement transformation quantity based on this displacement or angle. A second control analog quantity is generated based on the first displacement transformation quantity and the first control command quantity. Finally, the method receives the second control analog quantity and generates a second drive current based on it. This second drive current is then input into the axial piston pump to control its displacement to reach a target displacement. Therefore, by employing an electro-proportional displacement closed-loop control method, the displacement of the axial piston pump can be accurately controlled.

[0118] Corresponding to the closed-loop control system of the pump-controlled motor in the above embodiments, the present invention also proposes a closed-loop control method for the pump-controlled motor.

[0119] The pump-controlled motor is a fixed-displacement hydraulic motor. The oil inlet of the fixed-displacement hydraulic motor is connected to the oil outlet of the axial piston pump. Power is transmitted between the fixed-displacement hydraulic motor and the axial piston pump through an oil circuit.

[0120] like Figure 10 As shown, the closed-loop control method for a pump-controlled motor according to an embodiment of the present invention may include the following steps:

[0121] S701 receives the input instruction change quantity from the user and generates a first control instruction quantity based on the input instruction change quantity.

[0122] S702 receives the first control command quantity and generates the first control analog quantity based on the first control command quantity.

[0123] S703 receives a first control analog signal, generates a first drive current based on the first control analog signal, and inputs the first drive current into the axial piston pump to drive the axial piston pump to work. The axial piston pump drives the pump control motor.

[0124] S704 detects the first speed of the pump-controlled motor and generates a feedback speed change amount based on the first speed.

[0125] S705 receives the feedback speed change amount and generates a second control command amount based on the input command change amount and the feedback speed change amount.

[0126] In one embodiment of the present invention, generating a second control command quantity based on the input command change quantity and the feedback speed change quantity includes: calculating a second error between the input command change quantity and the feedback speed change quantity, and performing closed-loop dynamic adjustment on the second error to generate the second control command quantity.

[0127] S706 receives the second control command quantity and generates a third control analog quantity based on the second control command quantity.

[0128] S707 receives a third control analog signal, generates a third drive current based on the third control analog signal, and inputs the third drive current into the axial piston pump to adjust the displacement of the axial piston pump. The axial piston pump drives the pump control motor to operate at the target speed.

[0129] In one embodiment of the present invention, the closed-loop control method for the pump-controlled motor further includes: detecting the inlet oil pressure and outlet oil pressure of the pump-controlled motor, calculating a first pressure difference between the inlet oil pressure and the outlet oil pressure, and generating a pressure difference transformation quantity based on the first pressure difference; receiving the pressure difference transformation quantity, and generating a third control command quantity based on the input speed transformation quantity, the feedback speed transformation quantity, and the pressure difference transformation quantity; receiving the third control command quantity, and generating a fourth control analog quantity based on the third control command quantity; receiving the fourth control analog quantity, and generating a fourth drive current based on the fourth control analog quantity, and inputting the fourth drive current into the axial piston pump to adjust the displacement of the axial piston pump, wherein the axial piston pump drives the pump-controlled motor to operate at a target power, thereby achieving constant power adaptive control of the hydraulic motor to match the engine power.

[0130] In one embodiment of the present invention, generating a third control command quantity based on the input speed change quantity, the feedback speed change quantity, and the differential pressure change quantity includes: calculating the equivalent power of the pump-controlled motor using an equivalent power algorithm based on the feedback speed change quantity and the differential pressure change quantity; correcting the rated power setting value of the engine using a power correction algorithm based on the input speed change quantity to obtain a corresponding corrected power; calculating a third error between the equivalent power and the corrected power, and performing closed-loop dynamic adjustment on the third error to generate the third control command quantity.

[0131] It should be noted that more specific embodiments of the closed-loop control method for the pump-controlled motor of the present invention can be found in the embodiments of the closed-loop control system for the pump-controlled motor described above. To avoid redundancy, they will not be described in detail here.

[0132] According to an embodiment of the closed-loop control method for a pump-controlled motor, the method receives a user-inputted input command change quantity or input speed change quantity, generates a first control command quantity based on the input command change quantity or input speed change quantity, receives the first control command quantity, generates a first control analog quantity based on the first control command quantity, receives the first control analog quantity, generates a first drive current based on the first control analog quantity, and inputs the first drive current into an axial piston pump to drive the axial piston pump to work. The method also detects a first piston displacement or a first swashplate angle of the axial piston pump, generates a corresponding first displacement change quantity based on the first piston displacement or the first swashplate angle, generates a second control analog quantity based on the first displacement change quantity and the first control command quantity, receives the second control analog quantity, generates a second drive current based on the second control analog quantity, and inputs the second drive current into the axial piston pump to control the displacement of the axial piston pump to reach a target displacement.

[0133] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. "A plurality of" means two or more, unless otherwise explicitly specified.

[0134] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0135] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0136] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0137] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0138] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0139] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0140] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A closed-loop control system for an axial piston pump, characterized in that, include: The instruction generation module is used to receive input transformation quantities input by the user and generate a first control instruction quantity based on the input transformation quantities, wherein the input transformation quantities are input instruction transformation quantities or input speed transformation quantities; A displacement control module, wherein the displacement control module is used to receive the first control command quantity and generate a first control analog quantity according to the first control command quantity; A drive module is configured to receive the first control analog quantity, generate a first drive current based on the first control analog quantity, and input the first drive current into the axial piston pump to drive the axial piston pump to work. The displacement detection module is used to detect the first piston displacement or the first swashplate angle of the axial piston pump, and generate a corresponding first displacement change based on the first piston displacement or the first swashplate angle; wherein... The displacement control module is further configured to generate a second control analog quantity based on the first displacement change quantity and the first control command quantity. The drive module is also used to receive the second control analog quantity, generate a second drive current according to the second control analog quantity, and input the second drive current into the axial piston pump to control the displacement of the axial piston pump to reach the target displacement.

2. The closed-loop control system for the axial piston pump according to claim 1, characterized in that, The displacement control module is specifically used for: Calculate the first error between the first displacement change quantity and the first control command quantity, and perform closed-loop dynamic adjustment on the first error to generate the second control analog quantity.

3. A closed-loop control system for a pump-controlled motor, characterized in that, The pump-controlled motor is a fixed-displacement hydraulic motor. The inlet of the fixed-displacement hydraulic motor is connected to the outlet of the axial piston pump. Power transmission between the fixed-displacement hydraulic motor and the axial piston pump is achieved through an oil circuit. The closed-loop control system of the pump-controlled motor includes: The closed-loop control system of the axial piston pump as described in claim 1; A speed detection module is used to detect a first speed of the pump-controlled motor and generate a feedback speed change amount based on the first speed; wherein, The instruction generation module is further configured to receive the feedback speed change amount and generate a second control instruction amount based on the input instruction change amount and the feedback speed change amount. The displacement control module is also used to receive the second control command quantity and generate a third control analog quantity based on the second control command quantity. The drive module is also used to receive the third control analog quantity, generate a third drive current according to the third control analog quantity, and input the third drive current into the axial piston pump to adjust the displacement of the axial piston pump, wherein the axial piston pump drives the pump control motor to operate at a target speed.

4. The closed-loop control system for the pump-controlled motor according to claim 3, characterized in that, Also includes: The oil pressure detection module is used to detect the inlet oil pressure and outlet oil pressure of the pump-controlled motor, calculate a first pressure difference between the inlet oil pressure and the outlet oil pressure, and generate a pressure difference transformation quantity based on the first pressure difference; wherein, The instruction generation module is further configured to receive the differential pressure change quantity, and generate a third control instruction quantity based on the input speed change quantity, the feedback speed change quantity, and the differential pressure change quantity. The displacement control module is also used to receive the third control command quantity and generate a fourth control analog quantity based on the third control command quantity. The drive module is also used to receive the fourth control analog quantity, generate a fourth drive current according to the fourth control analog quantity, and input the fourth drive current into the axial piston pump to adjust the displacement of the axial piston pump, wherein the axial piston pump drives the pump control motor to operate at the target power.

5. The closed-loop control system for the pump-controlled motor according to claim 3, characterized in that, The instruction generation module is specifically used for: Calculate the second error between the input command change and the feedback speed change, and perform closed-loop dynamic adjustment on the second error to generate the second control command.

6. The closed-loop control system for the pump-controlled motor according to claim 4, characterized in that, The instruction generation module is specifically used for: The equivalent power of the pump-controlled motor is calculated using an equivalent power algorithm based on the feedback speed change and the pressure difference change. A power correction algorithm is used to correct the engine's rated power setting based on the input speed change, so as to obtain the corresponding corrected power. Calculate the third error between the equivalent power and the corrected power, perform closed-loop dynamic adjustment on the third error, and generate the third control command quantity based on the adjustment result.

7. A closed-loop control method for an axial piston pump, characterized in that, Includes the following steps: The system receives an input transformation quantity from the user and generates a first control command quantity based on the input transformation quantity, wherein the input transformation quantity is an input command transformation quantity or an input speed transformation quantity; Receive the first control command quantity, and generate a first control analog quantity based on the first control command quantity; The system receives the first control analog quantity, generates a first drive current based on the first control analog quantity, and inputs the first drive current into the axial piston pump to drive the axial piston pump to work. The first piston displacement or the first swashplate angle of the axial piston pump is detected, and a corresponding first displacement change is generated based on the first piston displacement or the first swashplate angle. A second control analog quantity is generated based on the first displacement change quantity and the first control command quantity; The system receives the second control analog quantity, generates a second drive current based on the second control analog quantity, and inputs the second drive current into the axial piston pump to control the displacement of the axial piston pump to reach the target displacement.

8. A closed-loop control method for a pump-controlled motor, characterized in that, The pump-controlled motor is a fixed-displacement hydraulic motor. The oil inlet of the fixed-displacement hydraulic motor is connected to the oil outlet of the axial piston pump. Power transmission between the fixed-displacement hydraulic motor and the axial piston pump is achieved through an oil circuit. The closed-loop control method of the pump-controlled motor includes the following steps: Receive the input instruction transformation quantity from the user, and generate a first control instruction quantity based on the input instruction transformation quantity; Receive the first control command quantity, and generate a first control analog quantity based on the first control command quantity; The system receives the first control analog quantity, generates a first drive current based on the first control analog quantity, and inputs the first drive current into the axial piston pump to drive the axial piston pump to work, wherein the axial piston pump drives the pump control motor to operate. The first rotational speed of the pump-controlled motor is detected, and a feedback rotational speed change is generated based on the first rotational speed. The system receives the feedback speed change amount and generates a second control command amount based on the input command change amount and the feedback speed change amount. The system receives the second control command quantity and generates a third control analog quantity based on the second control command quantity; wherein, the system detects the second piston displacement or the second swashplate angle of the axial piston pump and generates a corresponding second displacement change quantity based on the second piston displacement or the second swashplate angle, and generates a third control analog quantity based on the second control command quantity and the second displacement change quantity. The system receives the third control analog quantity, generates a third drive current based on the third control analog quantity, and inputs the third drive current into the axial piston pump to adjust the displacement of the axial piston pump, wherein the axial piston pump drives the pump control motor to operate at a target speed.

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