Servo motor, driver, control system and its control method

Abstract

The present invention provides a control system for a servo motor, which adopts a closed-loop control system and includes a first current controller, a second current controller, and a third current controller. The first current controller is used to implement the current closed-loop control of the servo motor, and the output of the first current controller serves as the output of the control system. The second current controller is set as the outer loop of the first current controller and is used to implement the speed closed-loop control of the servo motor. The third current controller is set as the outer loop of the second current controller and is used to implement the position closed-loop control of the servo motor. The closed-loop control system further includes a fourth current controller, which is set as the outer loop of the first current controller and the second current controller and is used to implement the closed-loop control of a fourth parameter of the servo motor. When the fourth parameter changes, the current and / or speed of the servo motor can be directly controlled and adjusted through the output signal of the fourth current controller.

Description

Technical Field

[0001] The present invention relates to the technical field of servo motor control, and particularly to a servo motor driver, a control system and a control method thereof. Background Art

[0002] The control system block diagram of a traditional servo motor is as Figure 1 shown. A servo motor includes a driver 10, and the driver 10 includes a control system 11. Among them, the control system 11 establishes a three-closed-loop control circuit for feedback of motor current, motor speed, and motor position to the servo driver according to a three-loop control scheme of current loop, speed loop, and position loop. Generally, the closed-loop design structure is from the inside out, designing the current loop, speed loop, and position loop in sequence. Among them, the current loop and speed loop are the inner loops of the position loop, and the current loop is the inner loop of the speed loop, that is, the output of the current loop is used as the output of the driver; the output of the speed loop is used as the input of the current loop, and the current of the servo motor is used as the negative feedback of the current loop; the output of the position loop is used as the input of the speed loop, and the speed of the servo motor is used as the negative feedback of the speed loop.

[0003] In addition to the three control parameters of current, speed, and position, other control parameters, such as pressure control parameters, etc., are to connect the feedback signal of the pressure sensor to the upper computer, and the output of the upper computer is used as the input of the position loop of the servo motor and connected to the control system of the servo motor. Due to the delay of internal and external communication of the servo motor and the calculation loop delay of the PID closed-loop control system, the control accuracy of the servo motor is low and the response speed is slow. Summary of the Invention

[0004] The purpose of the present invention is to provide a control method for a servo motor that can improve the control accuracy of the servo motor.

[0005] Corresponding to the purpose of the invention, another purpose of the present invention is to provide a control system, a driver and a servo motor for a servo motor that can improve the control accuracy of the servo motor.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] As an improved technical solution of the present invention:

[0008] A control method for a servo motor forms a four-loop control system through four current controllers. Among them, for the first closed-loop control system, the current closed-loop control of the servo motor is achieved through the first current controller; for the second closed-loop control system, by setting the second current controller as the outer loop of the first current controller, the speed closed-loop control of the servo motor is achieved; for the third closed-loop control system, by setting the third current controller as the outer loop of the second current controller, the position closed-loop control of the servo motor is achieved; for the fourth closed-loop control system, by setting the fourth current controller as the outer loop of the first current controller and the second current controller, the closed-loop control of the fourth parameter of the servo motor is achieved; when the fourth parameter changes, the current and / or speed of the servo motor can be directly controlled and adjusted through the output signal of the fourth current controller.

[0009] Preferably, the first current controller is a PI controller, the second current controller is a PI controller, the third current controller is a P controller, and the fourth current controller is a P controller.

[0010] The present invention also provides a control method for a servo system, which is a four-loop control system composed of a current loop, a speed loop, a position loop, and a pressure loop. The pressure loop and the position loop are the outer loops of the current loop and the speed loop, and the current loop is the inner loop of the speed loop. Among them, the pressure loop calculates and generates the output of the pressure loop according to the pressure detection data. The output of the pressure loop and the output of the position loop jointly serve as the input of the speed loop, and the output of the pressure loop also jointly serves as the input of the current loop with the output of the speed loop. When the pressure changes, the speed loop and / or the current loop can be directly controlled and adjusted through the output signal of the pressure loop.

[0011] Preferably, the current loop is a PI controller, the speed loop is a PI controller, the position loop is a P controller, and the pressure loop is a P controller.

[0012] The present invention further provides a control system for a servo motor, which adopts a closed-loop control system, including a closed-loop control system composed of a current loop, a speed loop, and a position loop. The output of the speed loop serves as the input of the current loop, and the current of the servo motor serves as the negative feedback of the current loop; the output of the position loop serves as the input of the speed loop, and the speed of the servo motor serves as the negative feedback of the speed loop. Among them, the closed-loop control system further includes a pressure loop to form a four-loop control system. The pressure loop calculates and generates the output of the pressure loop according to the pressure detection data. The output of the pressure loop and the output of the position loop jointly serve as the input of the speed loop, and the output of the pressure loop also jointly serves as the input of the current loop with the output of the speed loop. When the pressure changes, the speed loop and / or the current loop can be directly controlled and adjusted through the output signal of the pressure loop.

[0013] Preferably, the current loop is a PI controller, the speed loop is a PI controller, the position loop is a P controller, and the pressure loop is a P controller.

[0014] The present invention further provides a control system for a servo motor. The closed-loop control system includes a first current controller, a second current controller, and a third current controller. The first current controller is used to achieve current closed-loop control of the servo motor, and the output of the first current controller serves as the output of the control system. The second current controller is set as the outer loop of the first current controller and is used to achieve speed closed-loop control of the servo motor. The third current controller is set as the outer loop of the second current controller and is used to achieve position closed-loop control of the servo motor. Among them, the closed-loop control system further includes a fourth current controller. The fourth current controller is set as the outer loop of the first current controller and the second current controller and is used to achieve pressure closed-loop control of the servo motor, and together with the first current controller, the second current controller, and the third current controller, it forms a four-loop control system. When the pressure changes, the current and / or speed of the servo motor can be directly controlled and adjusted through the output signal of the fourth current controller.

[0015] Preferably, the first current controller is a PI controller, the second current controller is a PI controller, the third current controller is a P controller, and the fourth current controller is a P controller.

[0016] The present invention further provides a driver for a servo motor, which includes the above-mentioned control system for the servo motor, and further includes a PWM generator and a power inverter. The output of the control system for the servo motor serves as the input of the PWM generator, the output of the PWM generator serves as the input of the power inverter, and the output of the power inverter is used to supply power to the motor. When the fourth parameter pressure changes, the current and / or speed of the servo motor can be directly controlled and adjusted within the control system for the servo motor through the output signal of the pressure loop.

[0017] The present invention further provides a servo motor, which includes the above-mentioned driver for the servo motor, and further includes a motor controlled by the driver. The control accuracy of the servo motor is in the microsecond level, and collision protection can be achieved.

[0018] Through the above improvements, on the basis of the traditional three-loop (position loop, speed loop, current loop) control structure of the servo motor of the present invention, a pressure loop is added to form a four-loop control system. That is, according to the four-loop control scheme of current loop, speed loop, position loop, and pressure loop, a four-loop control circuit for current feedback, speed feedback, position feedback, and pressure feedback of the motor to the driver of the servo motor is established. Sampling sensor data and calculating errors can be realized inside the servo motor, so that the control and adjustment of the fourth parameter such as pressure can be completed at the same calculation speed as the control loops such as the current loop. The beneficial effects of the servo motor of the present invention are:

[0019] 1. Significantly improve the accuracy and response speed of pressure detection / control, and reduce costs;

[0020] 2. It can achieve double closed-loop mutual protection of pressure and position, avoid losses caused by out-of-control, and improve efficiency.

[0021] 3. It can achieve collision protection and can conveniently realize the design of protection functions for pressure or other fourth-parameter types. Description of the Drawings

[0022] Figure 1 It is a control system block diagram of an existing servo motor.

[0023] Figure 2 It is a control system block diagram of the servo motor of the present invention.

[0024] Figure 3 It is a structural block diagram of the control system of the servo motor of the present invention. Detailed Embodiment

[0025] The servo motor of the present invention includes a driver, and the driver includes a control system. The control system adopts a closed-loop control method and includes a first current controller, a second current controller, a third current controller, and a fourth current controller. The first current controller is used to achieve current closed-loop control of the servo motor, and the output of the first current controller is used as the output of the control system. The second current controller is set as the outer loop of the first current controller and is used to achieve speed closed-loop control of the servo motor. The third current controller is set as the outer loop of the second current controller and is used to achieve position closed-loop control of the servo motor. The fourth current controller is set as the outer loop of the first current controller and the second current controller and is used to achieve closed-loop control of the fourth parameter of the servo motor. When the fourth parameter changes, the current and / or speed of the servo motor can be directly controlled and adjusted through the output signal of the fourth current controller.

[0026] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] As Figure 2As shown in the figure, it is the control system block diagram of the servo motor of the present invention. A servo motor includes a driver 10, and the driver 10 includes a control system 11. The control system 11 adopts a closed-loop control method, including a current loop, a speed loop, a position loop, and a pressure loop. The pressure loop and the position loop are the outer loops of the current loop and the speed loop, and the current loop is the inner loop of the speed loop. That is, the output of the current loop is used as the output of the driver; the output of the current loop is used as the output of the control system; the output of the speed loop is used as the input of the current loop, and the current of the servo motor is used as the negative feedback of the current loop; the output of the position loop is used as the input of the speed loop, and the speed of the servo motor is used as the negative feedback of the speed loop; the pressure loop calculates and generates the output of the pressure loop according to the pressure detection data. The output of the pressure loop and the output of the position loop together are used as the input of the speed loop, and the output of the pressure loop is also used as the input of the current loop together with the output of the speed loop. When the pressure changes, the control adjustment of the speed loop and / or the current loop can be directly carried out through the output signal of the pressure loop. The pressure loop and the position loop of the control system of the servo motor of the present invention work independently. The pressure loop feedback can come from an external pressure sensor or an internal current feedback.

[0028] Preferably, the current loop is a PI controller (i.e., a proportional-integral controller), the speed loop is a PI controller (i.e., a proportional-integral controller), the position loop is a P controller (i.e., a proportional controller), and the pressure loop is a P controller (i.e., a proportional controller). The calculation formula of the pressure loop is (pressure command - pressure feedback) * Kp. By adjusting the size of the proportional coefficient Kp and cooperating with the parameter adjustment of the position loop, the speed loop, and the current loop, the speed of the pressure response and the detection accuracy can be adjusted.

[0029] The control principle of the servo motor of the present invention is to form a four-loop control system through four current controllers. Among them,

[0030] The first closed-loop control system realizes the current closed-loop control of the servo motor through the current loop, and the output of the current loop is used as the output of the control system;

[0031] The second closed-loop control system realizes the speed closed-loop control of the servo motor by setting the speed loop as the outer loop of the current loop;

[0032] The third closed-loop control system realizes the position closed-loop control of the servo motor by setting the position loop as the outer loop of the speed loop;

[0033] The fourth closed-loop control system realizes the pressure closed-loop control of the servo motor by setting the pressure loop as the outer loop of the current loop and the speed loop, that is, realizes the closed-loop control of the fourth parameter of the servo motor;

[0034] When the pressure changes, the control adjustment of the current and / or speed of the servo motor can be directly carried out through the output signal of the pressure loop.

[0035] The servo motor of the present invention, according to the four-loop control scheme of current loop, speed loop, position loop, and pressure loop, establishes a four-loop control circuit for current feedback, speed feedback, position feedback, and pressure feedback of the motor to the driver of the servo motor, that is, realizes the sampling sensor data and calculation error of the fourth parameter such as pressure in the servo motor, and then completes the control and adjustment of the servo motor, so as to be free from the delay interference of the communication bus, and enables the control and adjustment of the fourth parameter such as pressure to be processed at the same calculation speed as the internal loops such as the current loop of the servo motor, making the control accuracy of the servo motor of the present invention far exceed the current traditional methods. Compared with the prior art, the control system of the servo motor of the present invention can significantly improve the accuracy and response speed of pressure detection / control, reduce costs, and at the same time can achieve mutual protection of the pressure and position double closed loops, avoid losses caused by out-of-control, and improve efficiency.

[0036] After testing the servo motor prototypes of the same power level, the control accuracy of the servo motor of the prior art is at the millisecond level. While the control accuracy of the servo motor of the present invention can reach the microsecond level. The servo motor of the present invention can also achieve collision protection and can conveniently realize the design of protection functions for pressure type or other fourth parameter types.

[0037] As Figure 3 shown, it is the structural block diagram of the control system of the servo motor of the present invention, where the motor can be a three-phase motor. A servo motor includes a driver 10, and the driver 10 includes a control system 11. The control system 11 adopts a closed-loop control method, including a current loop, a speed loop, a position loop, and a pressure loop. The pressure loop and the position loop are the outer loops of the current loop and the speed loop, and the current loop is the inner loop of the speed loop.

[0038] The driver 10 further includes a PWM generator and a power inverter. The output of the control system 11 of the servo motor is used as the input of the PWM generator, the output of the PWM generator is used as the input of the power inverter, and the output of the power inverter is used to supply the three-phase motor.

[0039] The difference in control between the present invention and the prior art is that a closed-loop control circuit for the fourth parameter is added. The fourth parameter is preferably a pressure parameter. When the pressure changes, through the output signal of the pressure loop, the control and adjustment of the current and / or speed of the servo motor can be directly realized within the control system of the servo motor.

[0040] The above is only the preferred embodiment of the present invention. It should be noted that the above preferred embodiment should not be regarded as a limitation of the present invention. For those of ordinary skill in the art, without departing from the spirit and scope of the present invention, several improvements and retouches can still be made, and these improvements and retouches should also be regarded as the protection scope of the present invention. The protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A control method for a servo system, which is a four-loop control system composed of a current loop, a speed loop, a position loop, and a pressure loop. The pressure loop and the position loop are the outer loops of the current loop and the speed loop, and the current loop is the inner loop of the speed loop. Among them, The pressure loop calculates and generates the output of the pressure loop based on the pressure detection data. The output of the pressure loop and the output of the position loop jointly serve as the input of the speed loop, and the output of the pressure loop also jointly serves as the input of the current loop with the output of the speed loop. When the pressure changes, the speed loop and / or the current loop can be directly controlled and adjusted through the output signal of the pressure loop.

2. The control method for a servo system according to claim 1, characterized in that: The current loop is a PI controller, the speed loop is a PI controller, the position loop is a P controller, and the pressure loop is a P controller.

3. A control system for a servo motor, which adopts a closed-loop control system, including a first current controller, a second current controller, and a third current controller. The first current controller is used to implement the current closed-loop control of the servo motor, and the output of the first current controller serves as the output of the control system; the second current controller is set as the outer loop of the first current controller and is used to implement the speed closed-loop control of the servo motor; the third current controller is set as the outer loop of the second current controller and is used to implement the position closed-loop control of the servo motor. characterized in that: The closed-loop control system further includes a fourth current controller, which is set as the outer loop of the first current controller and the second current controller and is used to implement the closed-loop control of the servo motor. Among them, The output of the fourth current controller and the output of the third current controller jointly serve as the input of the second current controller, and the output of the fourth current controller also jointly serves as the input of the first current controller with the output of the second current controller. When the fourth parameter changes, the current and / or speed of the servo motor can be directly controlled and adjusted through the output signal of the fourth current controller.

4. The control system for a servo motor according to claim 3, characterized in that: The first current controller is a PI controller, the second current controller is a PI controller, the third current controller is a P controller, and the fourth current controller is a P controller.

5. A driver for a servo motor, characterized in that: It includes the control system for a servo motor according to claim 3 or 4, and further includes a PWM generator and a power inverter. The output of the control system for a servo motor serves as the input of the PWM generator, the output of the PWM generator serves as the input of the power inverter, and the output of the power inverter is used to supply power to the motor. When the fourth parameter pressure changes, the current and / or speed of the servo motor can be directly controlled and adjusted within the control system for a servo motor through the output signal of the pressure loop.

6. A servo motor, characterized in that: It includes the driver for a servo motor according to claim 5, and further includes a motor controlled by the driver. The control accuracy of the servo motor is at the microsecond level, and collision protection can be achieved.

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