An electric drive hydraulic system and an adaptive control method

Abstract

The present invention discloses an electric-drive hydraulic system and an adaptive control method. The electric-drive hydraulic system includes: a hydraulic pump, a drive motor, a motor controller, a vehicle controller, a pressure sensor, a battery system, and a hydraulic system operating mechanism. The vehicle controller is used to adaptively control the drive motor-hydraulic pump based on the hydraulic pump outlet pressure and output a motor speed control instruction to the motor controller. The adaptive control method establishes an optimal speed model for the drive motor based on the hydraulic pump pressure range and the corresponding motor speed range. The drive motor-hydraulic pump is adaptively controlled using a model reference adaptive control algorithm, using the established optimal speed model for the drive motor as a reference model, the hydraulic pump outlet pressure as input, and the motor speed control instruction as output. The present invention can adjust the motor speed in real time according to the actual hydraulic load so that it approaches the optimal speed, thereby reducing battery energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering machinery, and in particular to an electric drive hydraulic system and an adaptive control method. Background Art

[0002] With society's growing emphasis on environmental protection, traditional excavators, with their high levels of exhaust emissions, are no longer suitable for these new environmental requirements. Electric excavators are gradually replacing traditional excavators as a new development direction. Currently, most electric excavators utilize a motor + hydraulic pump drive system. Compared to electric hydraulic excavators, traditional excavators are limited by the narrow operating speed range of their diesel engines, resulting in less time spent operating within the energy-efficient range. Therefore, the motor + hydraulic pump drive system better meets the requirements of hydraulic load adaptive control.

[0003] Currently, most adaptive control technologies for motor + hydraulic pump drive methods use set load thresholds or load ranges to perform adaptive control of motor speed and hydraulic pump load. However, this control method has problems such as low control accuracy and inaccurate threshold settings, which will affect the effective control of the electric drive hydraulic system.

[0004] Chinese invention patent CN 106707753A discloses an adaptive control method for linear motors used in pumps. This method combines traditional PID control strategies with fuzzy PID control strategies. It can adaptively adjust the linear motor's PID parameters when the system load or operating speed changes, improving the robustness of the linear motor-driven plunger pump system and achieving vibration and noise reduction. However, its disadvantage is that the PID parameters are manually set, resulting in low accuracy. Chinese invention patent CN113818515A discloses a method, system, and device for adaptive power control of an electric excavator. The method includes: obtaining actual pressure values on the inlet and outlet oil lines of a hydraulic main pump; obtaining the initial speed of the drive motor and the initial current of the hydraulic main pump solenoid valve based on the gear set by the electric excavator; calculating the instantaneous power of the hydraulic main pump based on the obtained initial speed, initial current, and actual pressure values; calculating the calculated speed of the drive motor and the calculated current of the hydraulic main pump solenoid valve based on a pre-set speed range setting value and the instantaneous power of the hydraulic main pump; calculating the real-time set speed of the drive motor and the real-time set current of the hydraulic main pump solenoid valve; outputting the set speed value to a motor controller and outputting the set current to the hydraulic main pump solenoid valve, which controls the hydraulic main pump to achieve adaptive regulation. However, the disadvantage is that this calculation method has an oscillation range, which is not conducive to stable control of the motor. Chinese invention patent CN110836202A discloses a hydraulic source load adaptive system and adaptive control method. After the hydraulic source system is started, the speed of the DC synchronous motor reaches an initial value. As the load is turned off, all the oil flows through the relief valve and overflows back to the tank. The system pressure stabilizes at the relief pressure of the relief valve, and the system enters a relief state. When the load hydraulic cylinder moves to its farthest end or the load is maintaining pressure, the hydraulic source system enters a relief state. At this time, the pressure differential across the adjustable throttle valve is significantly greater than a reference value. However, when the system detects this condition, load adaptive control is disabled. If the detection system confirms the absence of an operating signal or a motion signal from the load hydraulic cylinder, the DC synchronous motor speed is reduced to a minimum value through differential pressure feedback from the adjustable throttle valve, reducing power consumption during load maintenance or system standby. However, this method's disadvantage is that it relies solely on the pressure differential across the throttle valve, which can easily lead to significant errors. Chinese invention patent CN110295635A discloses an electric bulldozer system and its power adaptive control method. The vehicle controller collects handle and throttle signals, outputs corresponding instructions to the motor controller, hydraulic pump, and hydraulic motor, and determines the current load based on feedback signals from the motor controller, hydraulic pump, and hydraulic motor. A first preset load and a second preset load are set, and the speed and torque of the bulldozer are adjusted based on the relationship between the current load and the two preset loads, as well as the current output to the hydraulic pump and hydraulic motor. However, the system's disadvantage is that the motor speed is adjusted based on the set load range within which the current load falls, resulting in low accuracy and poor adaptive control. Summary of the Invention

[0005] The purpose of the present invention is to provide an electric drive hydraulic system and an adaptive control method, which adopts a model reference adaptive control algorithm to adaptively control the drive motor-hydraulic pump, so as to achieve real-time adjustment of the motor speed according to the actual hydraulic load so that it approaches the optimal speed, thereby achieving the purpose of reducing battery energy consumption.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides an electric drive hydraulic system, comprising: a hydraulic pump, a drive motor, a motor controller, a vehicle controller, a pressure sensor, a battery system and a hydraulic system operating mechanism;

[0008] The driving motor is connected to the hydraulic pump and is used to provide power to the hydraulic pump;

[0009] The motor controller is connected to the drive motor and the vehicle controller, and is used to receive the motor speed control instruction and vehicle status transmitted by the vehicle controller, and control the speed of the drive motor and the start and stop of the drive motor;

[0010] The vehicle controller is connected to the motor controller, the battery system, the pressure sensor and the hydraulic system operating mechanism; the battery system is connected to the motor controller;

[0011] The vehicle controller is used to obtain the hydraulic pump outlet pressure data collected by the pressure sensor and the hydraulic load provided by the hydraulic system operating mechanism, control the motor controller; and manage the battery system.

[0012] Furthermore, the pressure sensor is installed at the outlet of the hydraulic pump.

[0013] Furthermore, the vehicle controller is specifically used to:

[0014] Parse the driver's operating instructions, monitor the vehicle status, and send vehicle control instructions and vehicle status to the motor controller; the vehicle control instructions include starting and stopping the drive motor.

[0015] Furthermore, the vehicle controller is specifically used to:

[0016] Obtain the hydraulic pump outlet pressure collected by the pressure sensor;

[0017] The drive motor-hydraulic pump is adaptively controlled based on the hydraulic pump outlet pressure, and the motor speed control command is output to the motor controller.

[0018] Furthermore, the vehicle controller is specifically used to:

[0019] When the hydraulic load changes, the motor speed is adjusted and a motor speed control instruction is output to the motor controller.

[0020] Furthermore, the vehicle controller is also used to:

[0021] The idle speed of the drive motor is controlled according to the hydraulic load and the hydraulic pump outlet pressure.

[0022] The present invention further provides an adaptive control method for an electric drive hydraulic system, for adaptively controlling the aforementioned electric drive hydraulic system, the method comprising:

[0023] Pre-collect the hydraulic pump outlet pressure and the corresponding motor speed within a certain period of time, and divide the hydraulic pump pressure range and the corresponding motor speed range;

[0024] Optimize the divided motor speed ranges to obtain the optimal speed corresponding to the hydraulic pump pressure range, and establish the optimal speed model of the drive motor;

[0025] Taking the established optimal speed model of the drive motor as the reference model, the outlet pressure of the hydraulic pump as the input, and the motor speed control command as the output, the model reference adaptive control algorithm is used to perform drive motor-hydraulic pump adaptive control.

[0026] Furthermore, the division of the hydraulic pump pressure range and the corresponding motor speed range includes:

[0027] Collect the hydraulic pump outlet pressure and the corresponding motor speed within a certain period of time, and supplement the singular values and missing data values;

[0028] According to the hydraulic pump outlet pressure range, the hydraulic pump pressure is divided into n different pressure intervals, namely (P0, P1), (P1, P2) ... (P n-1 ,P n );

[0029] According to the hydraulic pump outlet pressure, the corresponding motor speed range (n0,n1), (n1,n2)...(n n-1 ,n n ).

[0030] Furthermore, the divided motor speed intervals are optimized to obtain the optimal speed corresponding to the hydraulic pump pressure interval, and an optimal speed model for the drive motor is established, including:

[0031] The K-mean clustering algorithm is used to search for the optimal speed in the corresponding motor speed range for each hydraulic pump pressure range to obtain the corresponding optimal speed. The optimal speed corresponding to each hydraulic pump pressure range is then combined into the optimal speed model of the drive motor.

[0032] Furthermore, the drive motor-hydraulic pump adaptive control is performed using a model reference adaptive control algorithm with the established drive motor optimal speed model as a reference model, the hydraulic pump outlet pressure as input, and the motor speed control instruction as output, including:

[0033] The optimal speed model of the driving motor is used as the reference model in the model reference adaptive control to output the reference speed;

[0034] An adjustable controller is designed with the hydraulic pump outlet pressure as input and the drive motor speed control instruction as output. The output of the adjustable controller is expressed as:

[0035] n=f(P)+n g ;

[0036] Among them, n is the driving motor speed, P is the hydraulic pump outlet pressure, n g is the speed gain of the driving motor, the initial value is 0;

[0037] A controlled model of the drive motor is established with the drive motor as the controlled object, the control signal of the adjustable controller as the input, and the actual speed of the drive motor as the output;

[0038] The error Δn between the optimal speed output by the reference model and the actual speed output by the controlled object, and the hydraulic pump output pressure P are used as input to drive the motor speed gain n g For output, fuzzy rules are formulated, fuzzy adaptive mechanisms are constructed, and the speed gain of the driving motor is calculated in real time;

[0039] The calculated speed gain is input into the adjustable controller to obtain the speed control instruction of the drive motor.

[0040] Furthermore, the fuzzy rule is:

[0041] The fuzzy subset of the speed error Δn is defined as {-1000,-600,-200,0,200,600,1000}, and the corresponding linguistic variables are {nb,nm,ns,z,ps,pm,pb}; the fuzzy subset of the hydraulic pump outlet pressure P is defined as

[0042] {0,20,60,100}, the corresponding language variables are {z,s,m,b}; the speed gain of the driving motor is n g The fuzzy subset is defined as {-1000,-600,-200,0,200,600,1000}, and the corresponding linguistic variables are set to

[0043] {lb,lm,ls,z,rs,rm,rb}.

[0044] Furthermore, the control method further includes the step of automatically controlling the idle speed of the drive motor, as follows:

[0045] S1. Obtain the hydraulic load value of the hydraulic system operating mechanism at the current moment and compare it with the hydraulic load value at the previous moment. If there is no change, proceed to S2; if there is a change, proceed to S3;

[0046] S2. Obtain the current hydraulic pump outlet pressure and compare it with the pressure at the previous moment. If the difference between the two is less than the set idle pressure threshold and the duration is greater than the set idle time threshold, send a motor idle speed control command to the motor controller to control the drive motor to operate at the set idle speed, so that the entire machine enters the automatic idle state; otherwise, enter S3;

[0047] S3. Perform drive motor-hydraulic pump adaptive control based on the model reference adaptive control algorithm according to the current hydraulic pump outlet pressure, output the motor speed control command to the motor controller, control the drive motor to work according to the motor speed control command, and the whole machine exits the automatic idle state.

[0048] The beneficial effects of the present invention are:

[0049] This invention provides an electric-drive hydraulic system and adaptive control method. By collecting hydraulic pump pressure and the corresponding pump drive motor speed, a model for optimal motor speed is established. An adaptive motor speed adjustment mechanism is designed to adjust the motor speed in real time based on the actual hydraulic load, bringing it closer to the optimal speed and reducing battery energy consumption. This method can achieve real-time adjustment of the pump drive motor speed based on the hydraulic load, enabling adaptive control of the pump drive motor and also implementing adaptive process motor idle speed control. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A schematic diagram of the adaptive control principle of the electric drive hydraulic system provided by an embodiment of the present invention;

[0051] Figure 2 A diagram showing the fuzzy rule effect of the model reference adaptive adjustment mechanism provided by an embodiment of the present invention;

[0052] Figure 3 A model reference adaptive control flow chart provided by an embodiment of the present invention;

[0053] Figure 4 This is a flow chart of automatic idle control of an electric drive hydraulic system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0054] The present invention will be further described below. The following examples are only used to more clearly illustrate the technical solution of the present invention and are not intended to limit the scope of protection of the present invention.

[0055] Example 1

[0056] This embodiment provides an electric drive hydraulic system, including a hydraulic pump, a drive motor, a motor controller, a vehicle controller, a pressure sensor, a battery system and a hydraulic system operating mechanism.

[0057] Specifically, a hydraulic pump refers to a hydraulic component that provides pressurized liquid for hydraulic transmission and can convert the mechanical energy of the drive motor into the pressure energy of the liquid.

[0058] The drive motor and motor controller refer to the drive system that provides power to the hydraulic pump. In this embodiment, the drive motor is connected to the hydraulic pump to provide power to the hydraulic pump; the motor controller is connected to the drive motor and the vehicle controller to receive the motor speed control command or vehicle status transmitted by the vehicle controller, and control the drive motor speed and the start or stop of the drive motor.

[0059] The vehicle controller is the control center of the entire machine. In this embodiment, the vehicle controller is connected to the motor controller, battery system, pressure sensor and hydraulic system operating mechanism.

[0060] The vehicle controller is used to analyze the driver's operating instructions, monitor the vehicle status, and send vehicle control instructions and vehicle status to the motor controller;

[0061] The vehicle controller is also used to obtain the hydraulic pump outlet pressure collected by the pressure sensor, perform adaptive control of the drive motor-hydraulic pump based on the hydraulic pump pressure, and output the motor speed control command to the motor controller.

[0062] The vehicle controller is also used to obtain the load of the hydraulic system operating mechanism, adjust the motor speed when the hydraulic load changes, and control the idle speed of the drive motor according to the hydraulic load.

[0063] The vehicle controller is also used to manage the battery system.

[0064] In this embodiment, the pressure sensor is used to collect the pressure or flow at the outlet of the hydraulic pump and transmit the collected data to the vehicle controller. The pressure sensor is installed at the outlet of the hydraulic pump.

[0065] The battery system provides power to the electric drive system to ensure the normal operation of the entire electric drive system. In this embodiment, the battery system is connected to the motor controller.

[0066] In this embodiment, the hydraulic system operating mechanism is used to adjust the flow or pressure of the hydraulic system to achieve load regulation of the hydraulic system.

[0067] The electric drive hydraulic system provided in this embodiment can adjust the speed of the pump drive motor in real time according to the hydraulic load, realize dynamic adaptive control of the pump drive motor, and also realize adaptive process motor idle speed control.

[0068] Example 2

[0069] This embodiment provides an adaptive control method for an electric drive hydraulic system, which is used to implement the adaptive control process of the electric drive hydraulic system of embodiment 1. The basic principle of this method is shown in FIG. Figure 1 Specifically, the method includes: collecting the hydraulic pump output port pressure and the corresponding motor speed, dividing the hydraulic pump pressure range and the corresponding motor speed range; using the k-mean clustering algorithm to optimize each hydraulic pump pressure range, calculating the optimal motor speed for each pressure range, and establishing the optimal speed model of the drive motor, which is used as the motor reference speed; constructing a motor model, taking the hydraulic pump pressure value and the motor speed gain as input, controlling the motor model, and outputting the actual motor speed; constructing a fuzzy adaptive mechanism, taking the error value between the motor reference speed and the motor actual speed as input, and taking the motor speed gain as output, to perform drive motor-hydraulic pump adaptive control.

[0070] The specific implementation process of this method is as follows:

[0071] Pre-collect the hydraulic pump outlet pressure and the corresponding motor speed within a certain period of time, and divide the hydraulic pump pressure range and the corresponding motor speed range;

[0072] Optimize the divided motor speed ranges to obtain the optimal speed corresponding to the hydraulic pump pressure range, and establish the optimal speed model of the drive motor;

[0073] Taking the established optimal speed model of the driving motor as the theoretical model, the hydraulic pump pressure value as the input, and the motor speed control command as the output, the model reference adaptive control algorithm is used to perform motor-hydraulic pump adaptive control.

[0074] In this embodiment, the hydraulic pump pressure range and the corresponding motor speed range are divided, and the specific implementation process is as follows:

[0075] A pressure sensor is installed at the output end of the hydraulic pump to collect the pressure at the hydraulic pump output port and the corresponding motor speed over a certain period of time, and to supplement singular values and missing data values.

[0076] According to the pressure range of the hydraulic pump output port, the hydraulic pump pressure is divided into n different pressure intervals, namely (P0, P1), (P1, P2)... (P n-1 ,P n ), and obtain the corresponding speed range (n0,n1), (n1,n2)...(nn-1 ,n n ).

[0077] In this embodiment, the divided motor speed intervals are optimized to obtain the optimal speed corresponding to the hydraulic pump pressure interval, and an optimal speed model for the drive motor is established, including:

[0078] The K-mean clustering algorithm is used to find the optimal speed corresponding to each hydraulic pump pressure range, and the optimal speed of each hydraulic pump pressure range is combined into the optimal speed model of the drive motor.

[0079] The specific implementation process is as follows:

[0080] (1) Select the initial center value,

[0081] Select an initial value in each speed range, namely k1, k2...k n , as the initial center value of the k-mean clustering algorithm;

[0082] (2) Perform clustering optimization,

[0083] Calculate the distance between each sample and the initial center value within the speed range, and calculate the class to which any speed within the speed range should belong. Use the Euclidean distance measurement method. The larger the distance, the greater the difference between individuals.

[0084] (3) Re-clustering,

[0085] Re-determine the center value based on the calculation results;

[0086] (4) Iteration completed,

[0087] When the objective function reaches the optimal value or the maximum number of iterations is reached, the clustering optimization is terminated and the final cluster center k is obtained. o1 、k o2 ...k on , as the optimal speed value corresponding to each hydraulic pump pressure range, the corresponding speed values are n o1 、n o2 ...n on ;

[0088] (5) The optimal speed value n corresponding to each hydraulic pump pressure range o1 、n o2 ...n on Establish the optimal speed model of the drive motor.

[0089] It should be noted that, in other embodiments, a similar clustering algorithm may also be used to build an optimal speed model for the pump drive motor.

[0090] In this embodiment, the established optimal speed model of the drive motor is used as the theoretical model, the hydraulic pump pressure value is used as the input, and the motor speed control instruction is used as the output. The model reference adaptive control algorithm is used to perform motor-hydraulic pump adaptive control. The specific implementation process is as follows:

[0091] (1) The optimal speed model of the driving motor is used as the reference model in the model reference adaptive control to output the reference speed in the driving motor-hydraulic pump adaptive control method;

[0092] (2) An adjustable controller is designed with the hydraulic pump output pressure as input and the drive motor speed control instruction as output. The drive motor speed is a function of the hydraulic pump output pressure, and its calculation formula is as follows:

[0093] n=f(P)+n g ;

[0094] Where n is the output speed of the driving motor, P is the output pressure of the hydraulic pump, n g is the speed gain of the driving motor, the initial value is 0;

[0095] (3) Establish a controlled model of the drive motor with the drive motor as the controlled object, the control signal of the adjustable controller as the input, and the actual speed of the drive motor as the output;

[0096] (4) Using the fuzzy control method, a fuzzy adaptive mechanism is designed, with the error Δn between the optimal speed of the reference model and the actual speed of the controlled object and the output pressure P of the hydraulic pump as input to drive the motor speed gain n g For output, fuzzy rules are formulated to calculate the speed gain of the driving motor in real time.

[0097] The input variables of the fuzzy control algorithm are the speed error Δn and the hydraulic pump output pressure P, and the output variable is the drive motor speed gain n g The fuzzy subset of the speed error Δn is defined as {-1000,-600,-200,0,200,600,1000}, and the corresponding linguistic variables are {nb,nm,ns,z,ps,pm,pb}; the fuzzy subset of the hydraulic pump output pressure P is defined as {0,20,60,100}, and the corresponding linguistic variables are {z,s,m,b}; the drive motor speed gain n is defined as g The fuzzy subset is defined as {-1000,-600,-200,0,200,600,1000}, and the corresponding linguistic variables are set as {lb,lm,ls,z,rs,rm,rb}. The established fuzzy control rules are as follows: Figure 2 shown.

[0098] (5) The speed gain calculated by the fuzzy adaptive mechanism is input into the adjustable controller to obtain the speed control command of the drive motor. This algorithm modifies the motor speed control command of the adjustable controller in real time using the speed gain calculated by the fuzzy adaptive mechanism, so that the actual motor speed output by the controlled object approaches the corresponding speed of the optimal speed model.

[0099] It should be noted that in other embodiments, other algorithms may also be used to implement the same adaptive control function.

[0100] It should be noted that, see Figure 3 The speed gain is adjusted based on the speed error and the hydraulic pump output pressure. If the speed error is positive, the motor speed control command is less than the optimal motor speed, and the speed gain is positive, outputting a speed increase control command. If the speed error is negative, the motor speed control command is greater than the optimal motor speed, and a speed decrease control command is output until the motor error is zero. Then the motor idle speed determination is entered.

[0101] In another embodiment of the present invention, the control method further includes a process for automatically idling the drive motor. Automatic idle control refers to the process of automatically idling the entire machine when there is no input from the hydraulic system operating mechanism and the hydraulic load remains stable at a certain value for a long period of time. In this embodiment, whether the entire machine has entered the automatic idle state is determined based on the input signal from the hydraulic system operating mechanism and the hydraulic pump pressure signal transmitted by the pressure sensor. If there is no input from the hydraulic system operating mechanism and the hydraulic pump pressure signal remains at a certain value, the entire machine is determined to have entered the automatic idle state; otherwise, the entire machine does not enter the automatic idle state.

[0102] join Figure 4 In this embodiment, the automatic idle speed control of the drive motor includes:

[0103] S1. Obtain the hydraulic load value of the hydraulic system operating mechanism at the current moment and compare it with the hydraulic load value at the previous moment. If there is no change, proceed to S2; if there is a change, proceed to S3;

[0104] S2. Obtain the current hydraulic pump output pressure and compare it with the pressure at the previous moment. If the difference between the two is less than the set idle pressure threshold and the duration is greater than the set idle time threshold, send a motor idle speed control command to the motor controller to control the drive motor to operate at the set idle speed, so that the entire machine enters the automatic idle state; otherwise, enter S3;

[0105] S3. Perform motor-hydraulic pump adaptive control based on the model reference adaptive control algorithm according to the current hydraulic pump output pressure, output the motor speed control command to the motor controller, control the drive motor to work according to the motor speed control command, and the whole machine exits the automatic idle state.

[0106] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of this technology.

Claims

1. An adaptive control method for an electric drive hydraulic system, characterized in that: The method comprises: Pre-collect the hydraulic pump outlet pressure and the corresponding motor speed within a certain period of time, and divide the hydraulic pump pressure range and the corresponding motor speed range; Optimize the divided motor speed ranges to obtain the optimal speed corresponding to the hydraulic pump pressure range, and establish the optimal speed model of the drive motor; Taking the established optimal speed model of the drive motor as the reference model, the outlet pressure of the hydraulic pump as the input, and the motor speed control command as the output, the model reference adaptive control algorithm is used to perform drive motor-hydraulic pump adaptive control.

2. The adaptive control method of an electric drive hydraulic system according to claim 1, characterized in that: The electric drive hydraulic system includes: a hydraulic pump, a drive motor, a motor controller, a vehicle controller, a pressure sensor, a battery system and a hydraulic system operating mechanism; The driving motor is connected to the hydraulic pump and is used to provide power to the hydraulic pump; The motor controller is connected to the drive motor and the vehicle controller, and is used to receive the motor speed control instruction and vehicle status transmitted by the vehicle controller, and control the speed of the drive motor and the start and stop of the drive motor; The vehicle controller is connected to the motor controller, the battery system, the pressure sensor and the hydraulic system operating mechanism; the battery system is connected to the motor controller; The vehicle controller is used to obtain the hydraulic pump outlet pressure data collected by the pressure sensor and the hydraulic load provided by the hydraulic system operating mechanism, control the motor controller; and manage the battery system.

3. The adaptive control method of an electric drive hydraulic system according to claim 2, characterized in that: The pressure sensor is installed at the outlet of the hydraulic pump.

4. The adaptive control method of an electric drive hydraulic system according to claim 2, characterized in that: The vehicle controller is specifically used to: Parse the driver's operating instructions, monitor the vehicle status, and send vehicle control instructions and vehicle status to the motor controller; the vehicle control instructions include starting and stopping the drive motor.

5. The adaptive control method of an electric drive hydraulic system according to claim 3, characterized in that: The vehicle controller is specifically used to: Obtain the hydraulic pump outlet pressure collected by the pressure sensor; The drive motor-hydraulic pump is adaptively controlled based on the hydraulic pump outlet pressure, and the motor speed control command is output to the motor controller.

6. The adaptive control method of an electric drive hydraulic system according to claim 2, characterized in that: The vehicle controller is specifically used to: When the hydraulic load changes, the motor speed is adjusted and a motor speed control instruction is output to the motor controller.

7. The adaptive control method of an electric drive hydraulic system according to claim 6, characterized in that: The vehicle controller is also used to: The idle speed of the drive motor is controlled according to the hydraulic load and the hydraulic pump outlet pressure.

8. The adaptive control method of an electric drive hydraulic system according to claim 1, characterized in that: The division of the hydraulic pump pressure range and the corresponding motor speed range includes: Collect the hydraulic pump outlet pressure and the corresponding motor speed within a certain period of time, and supplement the singular values and missing data values; According to the hydraulic pump outlet pressure range, the hydraulic pump pressure is divided into n different pressure intervals, namely (P0, P1), (P1, P2) ... (P n-1 ,P n ); According to the hydraulic pump outlet pressure, the corresponding motor speed range (n0,n1), (n1,n2)...(n n-1 ,n n ).

9. The adaptive control method of an electric drive hydraulic system according to claim 8, characterized in that: Optimizing the divided motor speed intervals to obtain the optimal speed corresponding to the hydraulic pump pressure interval and establishing the optimal speed model of the drive motor includes: The K-mean clustering algorithm is used to search for the optimal speed in the corresponding motor speed range for each hydraulic pump pressure range to obtain the corresponding optimal speed. The optimal speed corresponding to each hydraulic pump pressure range is then combined into the optimal speed model of the drive motor.

10. The adaptive control method of an electric drive hydraulic system according to claim 9, characterized in that: The method uses the established optimal speed model of the drive motor as a reference model, the outlet pressure of the hydraulic pump as input, and the motor speed control instruction as output to perform the drive motor-hydraulic pump adaptive control using a model reference adaptive control algorithm, including: The optimal speed model of the driving motor is used as the reference model in the model reference adaptive control to output the reference speed; An adjustable controller is designed with the hydraulic pump outlet pressure as input and the drive motor speed control instruction as output. The output of the adjustable controller is expressed as: n=f(P)+n g ; Among them, n is the driving motor speed, P is the hydraulic pump outlet pressure, n g is the speed gain of the driving motor, the initial value is 0; A controlled model of the drive motor is established with the drive motor as the controlled object, the control signal of the adjustable controller as the input, and the actual speed of the drive motor as the output; The error Δn between the optimal speed output by the reference model and the actual speed output by the controlled object, and the hydraulic pump output pressure P are used as input to drive the motor speed gain n g For output, fuzzy rules are formulated, fuzzy adaptive mechanisms are constructed, and the speed gain of the driving motor is calculated in real time; The calculated speed gain is input into the adjustable controller to obtain the speed control instruction of the drive motor.

11. The adaptive control method of an electric drive hydraulic system according to claim 10, characterized in that: The fuzzy rules are: The fuzzy subset of the speed error Δn is defined as {-1000,-600,-200,0,200,600,1000}, and the corresponding linguistic variables are {nb,nm,ns,z,ps,pm,pb}; the fuzzy subset of the hydraulic pump outlet pressure P is defined as {0,20,60,100}, and the corresponding linguistic variables are {z,s,m,b}; the drive motor speed gain n is defined as g The fuzzy subset is defined as {-1000,-600,-200,0,200,600,1000}, and the corresponding linguistic variables are set to {lb,lm,ls,z,rs,rm,rb}.

12. The adaptive control method of an electric drive hydraulic system according to claim 10, characterized in that: The control method further includes the step of automatically controlling the idle speed of the drive motor, as follows: S1. Obtain the hydraulic load value of the hydraulic system operating mechanism at the current moment and compare it with the hydraulic load value at the previous moment. If there is no change, proceed to S2; if there is a change, proceed to S3; S2. Obtain the current hydraulic pump outlet pressure and compare it with the pressure at the previous moment. If the difference between the two is less than the set idle pressure threshold and the duration is greater than the set idle time threshold, send a motor idle speed control command to the motor controller to control the drive motor to operate at the set idle speed, so that the entire machine enters the automatic idle state; otherwise, enter S3; S3. Perform drive motor-hydraulic pump adaptive control based on the model reference adaptive control algorithm according to the current hydraulic pump outlet pressure, output the motor speed control command to the motor controller, control the drive motor to work according to the motor speed control command, and the whole machine exits the automatic idle state.

Images