Excavator electric slewing system and control method

Abstract

An excavator electric slewing system. The system comprises a joystick, tilt sensors (1, 2, 3, 4), a slew angle sensor (5), a weighing system, a main machine controller, a power supply system, a braking resistor, a slewing motor, and brakes; the joystick and the sensors are connected to an input terminal of the main machine controller; an output terminal of the main machine controller is connected to a control terminal of the brakes, and a communication port of the main machine controller is connected to a communication port of a motor controller and a communication port of the weighing system; and the motor controller is connected to the power supply system, the slewing motor, and the braking resistor, and the slewing motor is mechanically connected to the brakes and a reducer. The excavator electric slewing system improves both acceleration stability and stopping stability during the rotation process, preventing the problem of insufficient regenerative braking force of the motor at low speeds. Also disclosed is a control method for the excavator electric slewing system.

Description

Excavator electric rotary system and control method TECHNICAL FIELD

[0001] The present application belongs to the technical field of excavator rotary system, and particularly relates to an excavator electric rotary system and a control method. BACKGROUND

[0002] The hydraulic rotary system of an excavator cannot adjust the maximum working pressure of a rotary motor during rotation, which results in a large difference in acceleration and deceleration speed under different rotational inertia, and cannot achieve stable acceleration and deceleration, and the accurate operation of the rotary system relies on the experience of the driver. On the other hand, with the development of unmanned and remote control technology, the uncertainty of such a hydraulic rotary system cannot meet the requirements of accurate positioning of unmanned operation.

[0003] An electric rotary system can benefit from the flexibility of motor control, and more control methods and strategies can be adopted, but according to the working characteristics of the excavator rotary system, there are still some technical problems to be solved. For example, the braking of the motor can adopt energy consumption braking, electromagnetic braking, mechanical braking and the like, and the control strategy needs to be formulated according to the working characteristics, for example, when the excavator works on a slope, the rotary system needs to be braked to prevent the rotary system from sliding down the slope, and long-time energy consumption braking will cause the problem of motor heating and energy loss, and electromagnetic and mechanical braking will cause the problem of working load impact on the service life of the excavator.

[0004] For an electric rotary system, on the one hand, the system needs to be designed according to the working requirements of the equipment, and on the other hand, the control method needs to be designed according to the working condition characteristics. SUMMARY

[0005] To solve the above technical problems, the present application provides an excavator electric rotary system and a control method, which utilizes sensors, controllers and execution elements to perceive the working state changes of the excavator, and realizes the deceleration, stop, parking and safe and smooth rotary control under special working conditions of the electric rotary system through the algorithm of the built-in controller.

[0006] To achieve the above purpose, the present application adopts the following technical solutions:

[0007] A excavator electric slewing system, comprising: a handle, an inclination sensor I, an inclination sensor II, an inclination sensor III, an inclination sensor IV, a slewing angle sensor, a weighing system, a whole machine controller, a power supply system, a braking resistor, a slewing motor, an electromagnetic brake, a mechanical brake, a speed reducer; wherein the handle, the inclination sensor I, the inclination sensor II, the inclination sensor III, the inclination sensor IV, the slewing angle sensor are connected with the input port of the whole machine controller; the output port of the whole machine controller is connected with the control port of the electromagnetic brake and the mechanical brake, the communication port of the whole machine controller is connected with the communication port of the motor controller and the weighing system; the motor controller is connected with the power supply system, the slewing motor and the braking resistor, and the slewing motor is mechanically connected with the electromagnetic brake, the mechanical brake and the speed reducer.

[0008] The motor controller receives the motor control mode instruction sent by the whole machine controller, and controls the rotation speed and torque of the slewing motor.

[0009] Further, a control method of the excavator electric slewing system, comprising a start control method, a motion braking control method and a stop braking control method.

[0010] The start control method: in the acceleration initial t1 stage, the rotation angle acceleration design value α of the slewing motor is taken as the control target, the whole machine controller calculates and outputs the required slewing motor driving torque to the motor controller; when the target rotation speed of the slewing motor minus the actual rotation speed is lower than Δω, the whole machine controller sends the slewing motor control mode to the rotation speed control mode, and the motor rotation speed reaches the target rotation speed according to the design rule.

[0011] The motion braking control method: when the actual rotation speed of the slewing motor minus the target rotation speed is less than ω1, the regenerative braking and the electromagnetic braking are combined to brake; when the actual rotation speed of the slewing motor minus the target rotation speed is greater than or equal to ω1 or the actual rotation speed of the slewing motor is greater than ω2, the regenerative braking is adopted to brake.

[0012] The stop braking control method: when the upper vehicle of the excavator does not move, the electric slewing system adopts the mechanical brake, otherwise, the electric slewing system adopts the torque brake.

[0013] Further, the slewing motor driving torque calculation method in the start control method is:

[0014] The required slewing motor driving torque is calculated according to the real-time rotation inertia of the whole machine, the rotation angle acceleration design value of the whole machine and the inclination of the whole machine:

[0015] N=Jα+N θ +N f

[0016] In the formula:

[0017] J-Real-time moment of inertia of the whole machine converted to the moment of inertia of the output shaft of the rotary motor;

[0018] α-Designed angular acceleration of the rotary motor during acceleration;

[0019] N θ -Real-time moment of inertia of the whole machine converted to the moment of inertia of the output shaft of the rotary motor;

[0020] N f -Real-time moment of inertia of the whole machine converted to the moment of inertia of the output shaft of the rotary motor;

[0021] Further, the method for converting the real-time moment of inertia of the whole machine to the moment of inertia of the output shaft of the rotary motor is:

[0022] J = J0 + J1 + J2 + J3 + J w

[0023] In the formula:

[0024] J0-Real-time moment of inertia of the whole machine converted to the moment of inertia of the output shaft of the rotary motor;

[0025] J1-Real-time moment of inertia of the component measured by the tilt angle sensor I converted to the moment of inertia of the output shaft of the rotary motor;

[0026] J2-Real-time moment of inertia of the component measured by the tilt angle sensor II converted to the moment of inertia of the output shaft of the rotary motor;

[0027] J3-Real-time moment of inertia of the component measured by the tilt angle sensor III converted to the moment of inertia of the output shaft of the rotary motor;

[0028] J w -Real-time moment of inertia of the component measured by the tilt angle sensor III converted to the moment of inertia of the output shaft of the rotary motor;

[0029] Further, in the braking control method during motion, regenerative braking is controlled to convert the rotary motor into a generator working state, generate a torque opposite to the rotation direction, and output electric energy.

[0030] Further, in the braking control method during motion, when the rotary motor is in regenerative braking, the regenerated electric energy is consumed through a brake resistor by a motor controller.

[0031] Further, in the braking control method during motion, when the rotary motor is in regenerative braking, the regenerated electric energy is input into a power supply system by a motor controller.

[0032] Further, in the motion-time braking control method, the rotary motor regenerative braking torque calculation method is:

[0033] According to the real-time moment of inertia of the whole machine, the design value of the angular acceleration of the whole machine, and the inclination angle, a required rotary motor driving torque is calculated:

[0034] N z = J z -N θ -N f

[0035] In the formula: J is the moment of inertia of the real-time rotary motor output shaft;

[0036] α z is the design value of the angular acceleration of the rotary motor rotation deceleration;

[0037] N θ is the torque of the whole machine inclination torque converted to the rotary motor output shaft;

[0038] N f is the rotary torque of the whole machine friction torque converted to the rotary motor output shaft.

[0039] Compared with the prior art, the advantages of the present application are:

[0040] The present application calculates the real-time torque value of the rotary motor by using the dynamic moment of inertia, which can improve the acceleration stability during rotation.

[0041] When the rotary motion stops, the present application adopts a combination of regenerative braking and electromagnetic braking, which avoids the problem of insufficient regenerative braking force of the motor at low speed.

[0042] When the rotary motion stops, the present application calculates the real-time deceleration torque value of the rotary motor by using the dynamic moment of inertia, which can improve the stability during rotation stop.

[0043] When the rotary system stops, the present application adopts a combination of torque braking and mechanical braking, which is more widely applicable and more reliable. BRIEF DESCRIPTION OF DRAWINGS

[0044] Fig. 1 is a structural schematic diagram of an electric rotary system of an excavator;

[0045] Fig. 2 is a schematic diagram of the installation positions of various sensors of the electric rotary system of the excavator;

[0046] Fig. 3 is an example of the angular acceleration and angular velocity of the rotary motor;

[0047] In Fig. 2: 1 is an inclination angle sensor I; 2 is an inclination angle sensor II; 3 is an inclination angle sensor III; 4 is an inclination angle sensor IV; 5 is a rotary angle sensor;

[0048] In Fig. 3: a, angular acceleration of the rotary motor; b, angular velocity of the rotary motor. DETAILED DESCRIPTION

[0049] The technical solutions of the present application will be described in detail below with reference to the drawings and specific embodiments. It should be understood that the embodiments and specific features in the embodiments of the present application are detailed descriptions of the technical solutions of the present application, and not limitations of the technical solutions of the present application. In the case of no conflict, the technical features in the embodiments and the embodiments of the present application can be combined with each other.

[0050] The term "and / or" herein is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " herein generally represents that the front and rear associated objects have an "or" relationship.

[0051] As shown in Figs. 1 to 3, the present application provides an excavator electric rotary system, which uses sensors, controllers and execution elements to perceive the change of the working state of the excavator, and realizes the speed reduction, stop, parking and safe and smooth rotary control in special working conditions of the electric rotary system through the algorithm of the built-in controller.

[0052] An excavator electric rotary system, comprising: a handle, an inclination sensor I1, an inclination sensor II2, an inclination sensor III3, an inclination sensor IV4, a rotary angle sensor 5, a weighing system, a whole machine controller, a motor controller, a power supply system, a braking resistor, a rotary motor, an electromagnetic brake, a mechanical brake, a speed reducer. The handle, the inclination sensor I1, the inclination sensor II2, the inclination sensor III3, the inclination sensor IV4 and the rotary angle sensor 5 are connected with the input port of the whole machine controller, the output port of the whole machine controller is connected with the control port of the electromagnetic brake and the mechanical brake, and the communication port of the whole machine controller is connected with the communication port of the motor controller and the weighing system. The motor controller is connected with the power supply system, the rotary motor and the braking resistor, and the rotary motor is mechanically connected with the electromagnetic brake, the mechanical brake and the speed reducer.

[0053] The handle outputs forward rotary control signal, reverse rotary control signal and signal size.

[0054] The inclination sensor I1, the inclination sensor II2, the inclination sensor III3 and the inclination sensor IV4 are respectively installed on the excavator bucket, the bucket rod, the boom and the turret, and are used for testing the attitude angle of the bucket, the attitude angle of the bucket rod, the attitude angle of the boom and the attitude angle of the turret.

[0055] The rotary angle sensor 5 is installed on the turret of the excavator and is used for testing the rotary angle of the turret and the rotary motor rotation angular acceleration.

[0056] The weighing system is used to weigh the material in the excavator bucket, and can send the weighing data to the whole machine controller.

[0057] The whole machine controller collects the inclination sensor signals and communicates with the weighing system and the motor controller.

[0058] The power supply system is used to supply power to the electric rotary system.

[0059] The braking resistor is used to consume the electric energy generated by the motor during motor regenerative braking.

[0060] The rotary motor is used to drive the rotation of the rotary system.

[0061] The electromagnetic brake can control the braking force through an electric control signal.

[0062] The mechanical brake is used to brake the electric rotary system in a mechanical manner.

[0063] The speed reducer is used to convert the high rotational speed output by the rotary motor into a low rotational speed for driving the equipment to rotate.

[0064] The whole machine controller collects the inclination sensor I1, inclination sensor II2, inclination sensor III3, and inclination sensor IV4 parameters, and then calculates the whole machine rotational inertia in real time according to the structure and center of gravity parameters of each moving part of the excavator. Through communication with the weighing system, the current material mass in the bucket is obtained, the default material center of gravity is assumed to coincide with the bucket center of gravity, and the material rotational inertia is calculated.

[0065] The excavator electric rotary system startup control method uses the rotary motor rotational angular acceleration design value α as the control target in the acceleration initial t1 stage, and the whole machine controller calculates and outputs the required rotary motor driving torque to the motor controller. When the target rotational speed of the rotary motor minus the actual rotational speed is lower than Δω, the whole machine controller sends the rotary motor control mode to the rotational speed control mode, and the motor rotational speed reaches the target rotational speed according to the design law.

[0066] Δω represents the degree to which the actual rotational speed approaches the target rotational speed in the startup process, and is a design value. When the target rotational speed of the rotary motor minus the actual rotational speed is < Δω, it indicates that the actual rotational speed approaches the target rotational speed.

[0067] The rotary motor driving torque calculation method is:

[0068] The required rotary motor driving torque is calculated according to the whole machine real-time rotational inertia, the whole machine rotational angular acceleration design value, and the whole machine inclination.

[0069] N = Jα + N θ +N f

[0070] In the formula:

[0071] J- the real-time moment of inertia of the whole machine converted to the moment of inertia of the output shaft of the rotary motor;

[0072] α- the designed angular acceleration value when the rotary motor rotates at high speed;

[0073] N θ - the torque of the whole machine converted to the torque of the output shaft of the rotary motor, which is the torque generated by the inclination, and is determined by real-time calculation of the inclination sensor IV, the rotary angle sensor 5, the state of the whole machine affected by gravity, the transmission ratio, etc.

[0074] N f - the friction torque of the whole machine converted to the rotational torque of the output shaft of the rotary motor.

[0075] The calculation method of the real-time moment of inertia of the whole machine converted to the moment of inertia of the output shaft of the rotary motor is:

[0076] J = J0 + J1 + J2 + J3 + J w

[0077] In the formula:

[0078] J0- the moment of inertia of the whole machine relative to the unchanged part of the rotary center of the whole machine, converted to the moment of inertia of the output shaft of the rotary motor;

[0079] J1- the moment of inertia of the component measured by the inclination sensor I relative to the rotary center of the whole machine, converted to the moment of inertia of the output shaft of the rotary motor;

[0080] J2- the moment of inertia of the component measured by the inclination sensor II relative to the rotary center of the whole machine, converted to the moment of inertia of the output shaft of the rotary motor;

[0081] J3- the moment of inertia of the component measured by the inclination sensor III relative to the rotary center of the whole machine, converted to the moment of inertia of the output shaft of the rotary motor;

[0082] J w - the moment of inertia of the material measured by the weighing system relative to the rotary center of the whole machine, converted to the moment of inertia of the output shaft of the rotary motor;

[0083] The braking control method of the electric rotary system of the excavator when moving, when the actual speed of the rotary motor minus the target speed is less than ω1, the regenerative braking and electromagnetic braking are combined, when the actual speed of the rotary motor minus the target speed is greater than or equal to ω1 or the actual speed of the rotary motor is greater than ω2, the regenerative braking is used to brake.

[0084] ω1, ω2 represent the degree of actual speed of the motor approaching the target speed, and are design values, ω1 represents the actual speed of the motor approaching the target speed, and ω2 represents the actual speed of the motor being relatively high, ω1 < ω2. When the actual speed of the motor minus the target speed is less than ω1, it indicates that the actual speed of the motor is relatively low, and the regenerative braking force is too small due to the low speed, and the electromagnetic brake needs to be added to provide a larger braking force. When the actual speed of the motor minus the target speed is greater than or equal to ω1 or the actual speed of the motor is greater than ω2, the actual speed of the motor is not lower than the target speed, or is much higher than the target speed, at this time, the regenerative braking force is large enough to meet the braking demand, and the braking adopts regenerative braking.

[0085] The regenerative braking is to control the motor to convert to a generator working state to generate a torque opposite to the rotation direction and emit electric energy.

[0086] When the regenerative braking of the motor is in effect, the motor controller is used to dissipate the regenerated electric energy through a braking resistor.

[0087] When the regenerative braking of the motor is in effect, the motor controller is used to input the regenerated electric energy into the power supply system.

[0088] The calculation method of the regenerative braking torque of the motor is:

[0089] The required motor driving torque is calculated according to the whole machine moment of inertia, the whole machine angular acceleration design value, and the whole machine tilt angle, etc.

[0090] N z = Jα z -N θ -N f

[0091] In the formula, J is the real-time moment of inertia of the whole machine converted to the moment of inertia of the motor output shaft;

[0092] α z is the angular acceleration design value when the motor is decelerating;

[0093] N θ is the torque of the whole machine tilt converted to the torque of the motor output shaft;

[0094] N f is the friction torque of the whole machine converted to the rotational torque of the motor output shaft.

[0095] The braking control method of the electric motor system of the excavator when it is stopped is that when the upper vehicle of the excavator is not moving, the electric motor system uses mechanical braking, otherwise, the electric motor system uses torque braking.

[0096] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present application, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. An excavator electric swing system, characterized by, It comprises a handle, an inclination sensor I, an inclination sensor II, an inclination sensor III, an inclination sensor IV, a rotation angle sensor, a weighing system, a whole machine controller, a power supply system, a braking resistor, a rotary motor, an electromagnetic brake, a mechanical brake, and a speed reducer, wherein the handle, the inclination sensor I, the inclination sensor II, the inclination sensor III, the inclination sensor IV, and the rotation angle sensor are connected with an input port of the whole machine controller; an output port of the whole machine controller is connected with control ports of the electromagnetic brake and the mechanical brake; a communication port of the whole machine controller is connected with a communication port of a motor controller and a communication port of the weighing system; the motor controller is connected with the power supply system, the rotary motor, and the braking resistor; and the rotary motor is mechanically connected with the electromagnetic brake, the mechanical brake, and the speed reducer. The motor controller receives a motor control mode instruction sent by the whole machine controller, and controls the rotation speed and the torque of the rotary motor. The control method comprises a start control method, a movement braking control method, and a stop braking control method.

2. A control method of the excavator electric swing system according to claim 1, characterized by, In the start control method, at an acceleration initial t1 stage, a rotary motor rotation angle acceleration design value α is taken as a control target, the whole machine controller calculates and outputs a required rotary motor driving torque to the motor controller; when a rotary motor target rotation speed minus an actual rotation speed is lower than Δω, the whole machine controller sends a rotary motor control mode as a rotation speed control mode, and the motor rotation speed reaches the target rotation speed according to a design rule. In the movement braking control method, when the rotary motor actual rotation speed minus the target rotation speed is less than ω1, a regenerative braking and an electromagnetic braking are combined; when the rotary motor actual rotation speed minus the target rotation speed is greater than or equal to ω1 or the rotary motor actual rotation speed is greater than ω2, a regenerative braking is adopted. In the stop braking control method, when the excavator upper vehicle is not in action, the electric rotary system adopts the mechanical braking; otherwise, the electric rotary system adopts the torque braking. In the start control method, the rotary motor driving torque calculation method is as follows:

3. The control method of the excavator electric swing system according to claim 2, characterized by, The required rotary motor driving torque is calculated according to the whole machine real-time moment of inertia, the whole machine rotation angle acceleration design value, and the whole machine inclination. In the formula, J is the whole machine real-time moment of inertia converted to the moment of inertia of the rotary motor output shaft; and α is the rotary motor rotation acceleration design value. N = Jα + N θ + N f In the formula, J0 is the whole machine moment of inertia relative to the whole machine rotary center constant part converted to the moment of inertia of the rotary motor output shaft; J1 is the moment of inertia of the component measured by the inclination sensor I relative to the whole machine rotary center converted to the moment of inertia of the rotary motor output shaft; J2 is the moment of inertia of the component measured by the inclination sensor II relative to the whole machine rotary center converted to the moment of inertia of the rotary motor output shaft; and J3 is the moment of inertia of the component measured by the inclination sensor III relative to the whole machine rotary center converted to the moment of inertia of the rotary motor output shaft. In the movement braking control method, the regenerative braking is to control the rotary motor to convert to a generator working state to generate a torque opposite to the rotation direction and to output electric energy. In the movement braking control method, when the rotary motor regenerative braking works, the motor controller is used to consume the regenerated electric energy through the braking resistor. N θ - the whole machine tilting torque converted to the rotary electric machine output shaft torque; N f - The whole machine friction torque is converted to the rotating torque of the motor output shaft.

4. The control method of the excavator electric swing system according to claim 3, characterized by, The method for converting the real-time moment of inertia of the whole machine to the moment of inertia of the output shaft of the rotary motor is: J=J0+J1+J2+J3+J w ​ ​ ​ ​ ​ J w - the relative moment of inertia of the material measured by the weighing system, converted to the moment of inertia of the output shaft of the rotary motor.

5. The control method of the excavator electric swing system according to claim 2, characterized by, ​ 6. The control method of the excavator electric swing system according to claim 2, characterized by, ​ 7. The control method of the excavator electric swing system according to claim 2, characterized by, In the motion braking control method, when the rotary motor works in the regenerative braking mode, the motor controller inputs the regenerated electric energy into the power supply system.

8. The control method of the excavator electric swing system according to claim 2, characterized by, In the motion braking control method, the rotary motor regenerative braking torque calculation method is: The required rotary motor driving torque is calculated according to the whole machine rotational inertia, the whole machine rotational angular acceleration design value, and the whole machine inclination angle, etc. N s = Jα s -N θ -N f In the formula, J is the whole machine real-time rotational inertia converted to the rotational inertia of the rotary motor output shaft. alpha z - the design value of the angular acceleration of the rotary electric machine at the time of deceleration N θ - the whole machine tilting torque converted to the rotary electric machine output shaft torque; N f - The whole machine friction torque is converted to the rotating torque of the motor output shaft.

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