Resonance suppression method for flexible system structure of low-rigidity heavy-load permanent magnet synchronous motor

Abstract

The invention discloses a low-rigidity heavy-load permanent magnet synchronous motor flexible system structure resonance suppression method, and relates to the technical field of permanent magnet synchronous motor control, and the method comprises the steps: carrying out the dynamic filtering of an input position signal through setting a TD tracking differentiator, and generating a smooth planning instruction and a differential signal thereof; based on the planned instruction differential signal, a speed feed-forward control method is adopted to introduce feed-forward compensation in a position closed loop; constructing a disturbance observer according to the electromagnetic torque equation of the motor, estimating the actual wheelbase of the system in real time, and performing disturbance compensation; based on system resonance characteristics, an IP control method is adopted to perform pole assignment, and proportional gain and integral gain are set to suppress structure resonance and optimize closed-loop response. According to the method, a relatively good resonance suppression effect can be achieved without displacement, speed or acceleration signals of a load end and information such as very accurate load resonant frequency, relatively good dynamic response is achieved, and the requirement on hardware is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of permanent magnet synchronous motor control, and particularly to a method for suppressing the structural resonance of a flexible system of a permanent magnet synchronous motor with low stiffness and large load. Background Art

[0002] A permanent magnet synchronous motor control system generally includes a servo motor, a transmission mechanism, a connecting mechanism, a load, etc. Its simplified block diagram is as Figure 2 shown, where K is the mechanical stiffness of the system, is the mass of the motor, is the mass of the transmission structure and the connecting mechanism, is the mass of the load, is the moment of inertia of the motor and the transmission mechanism, and x respectively represent the motor rotation angle and the linear displacement, and respectively represent the electromagnetic torque of the motor and the external load. Due to constraints in aspects such as structural space, volume, and weight, generally, the permanent magnet synchronous motor control system uses lightweight materials in its structure, and the mechanical stiffness K is not high. Under large load conditions, it causes structural deformation, is prone to resonance, inaccurate positioning, and even leads to system instability.

[0003] For a flexible system, the load object cannot be simply modeled as a first-order inertial link. The flexible structure enables the load to be decomposed into a series of an inertial link and a resonator in the frequency domain. The phase lag characteristic of the resonance point will affect the stability of the control system, and the anti-resonance point will increase the amplitude-frequency of the position closed-loop, thus causing jitter during positioning. Generally, a notch filter can be used to suppress resonance, but a fatal disadvantage of the notch filter is that the passband range corresponds to a certain phase angle lag, and the wider the passband, the more serious the phase angle lag; moreover, from the perspective of the suppression depth, the wider the passband, the less obvious the suppression effect; selecting a narrow-bandwidth notch filter is mostly affected by the accuracy of the identification of the resonance frequency band.

[0004] Therefore, a method for suppressing the structural resonance of a flexible system of a permanent magnet synchronous motor with low stiffness and large load is proposed. Summary of the Invention

[0005] The purpose of the present invention is to design a method for suppressing the structural resonance of a flexible system of a permanent magnet synchronous motor with low stiffness and large load, which is used to solve problems such as system mechanism resonance, resulting in low control performance and weak system stability under the state of low stiffness and large load. The aim is to improve the control accuracy and dynamic response ability of the load end of the permanent magnet synchronous motor flexible system and suppress structural resonance.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: In a first aspect, an embodiment of the present invention provides a method for suppressing the structural resonance of a flexible system of a low-stiffness and large-load permanent magnet synchronous motor, including: Tracking differentiator path planning: Dynamically filtering the input position signal through a set TD tracking differentiator to generate a smooth planning instruction and its differential signal; Speed feedforward control: Based on the planned instruction differential signal, introducing a feedforward compensation in the position closed-loop by using the speed feedforward method; Establishment and compensation of a disturbance observer: Constructing a disturbance observer according to the motor electromagnetic torque equation, estimating the actual shaft pitch of the system in real time and performing disturbance compensation; Pole configuration of the IP controller: Based on the resonance characteristics of the system, performing pole configuration by using the IP control method, and setting the proportional gain and integral gain to suppress the structural resonance and optimize the closed-loop response.

[0007] As a preferred solution of the method for suppressing the structural resonance of the flexible system of the low-stiffness and large-load permanent magnet synchronous motor according to the present invention, wherein: The TD tracking differentiator is based on the fastest synthesis function, combines the set tracking acceleration factor and filtering factor, realizes the smooth transition and differential output of the position signal, and reduces the lag error introduced in the planning process through phase compensation.

[0008] As a preferred solution of the method for suppressing the structural resonance of the flexible system of the low-stiffness and large-load permanent magnet synchronous motor according to the present invention, wherein: The speed feedforward control calculates a feedforward torque signal according to the planned speed signal, and superimposes the feedforward torque and the feedback control torque to compensate for the hysteresis caused by the rotational inertia of the motor.

[0009] As a preferred solution of the method for suppressing the structural resonance of the flexible system of the low-stiffness and large-load permanent magnet synchronous motor according to the present invention, wherein: The disturbance observer estimates the disturbance based on the feedback speed signal and the motor output torque signal, the observer uses the filtering frequency parameter to suppress high-frequency noise, and the observed shaft pitch output is used to compensate for the low-stiffness effect caused by the flexible structure.

[0010] As a preferred solution of the method for suppressing the structural resonance of the flexible system of the low-stiffness and large-load permanent magnet synchronous motor according to the present invention, wherein: The electromagnetic torque in the disturbance observer is obtained by calculating the shaft current feedback, multiplying the torque coefficient and the current signal to obtain the electromagnetic torque signal to participate in the disturbance observation operation.

[0011] As a preferred solution of the method for suppressing the structural resonance of the flexible system of the low-stiffness and large-load permanent magnet synchronous motor according to the present invention, wherein: The proportional gain and integral gain of the IP controller are calculated and determined according to the load resonance frequency, system rotational inertia and mechanical stiffness parameters, and the pole configuration gives priority to improving the system damping ratio, reducing the resonance peak amplitude, and making a trade-off between the overshoot and the response speed according to different application requirements.

[0012] As a preferred solution of the method for suppressing the structural resonance of the flexible system of the low-rigidity and high-load permanent magnet synchronous motor of the present invention, wherein: the resonant frequency is calculated based on the structural stiffness of the servo system and the load mass, specifically, Determine, where K is the structural stiffness of the servo system, The load mass is calculated and the resonance characteristics are corrected according to the total transmission ratio of the servo system to guide the parameter setting of the IP controller.

[0013] In the second aspect, in order to further solve the problems existing in the control of permanent magnet synchronous motors, the present invention provides a low-rigidity and large-load permanent magnet synchronous motor flexible system structural resonance suppression system in an embodiment, which includes: a path planning module, which uses a tracking differentiator to filter and plan the path of the position command signal; a feedforward and feedback control module, which is used to perform position loop closed-loop control and speed feedforward compensation based on the reference signal generated by the path planning module; a disturbance observation module, which is used to estimate the vibration disturbance of the flexible structure in real time according to the motor operating parameters, and output a disturbance compensation signal; a pole configuration and IP control module, which is used to use an IP controller to configure the poles of the system according to the output result of the disturbance observation module.

[0014] In a third aspect, an embodiment of the present invention provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program is executed by the processor, any step of the method for suppressing structural resonance of a flexible system of a low-stiffness and large-load permanent magnet synchronous motor as described in the first aspect of the present invention is implemented.

[0015] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, any step of the method for suppressing structural resonance of a flexible system of a low-stiffness and large-load permanent magnet synchronous motor as described in the first aspect of the present invention is implemented.

[0016] The beneficial effects of the present invention are: 1. This method does not require displacement, velocity or acceleration signals at the load end, nor does it require very accurate information such as the load resonance frequency. It can also achieve good resonance suppression effects and has good dynamic response, reducing the demand for hardware; 2. The present invention is based on the system control principle diagram and can be used for fast system simulation. At the same time, the scheme is easy to adjust parameters. The bandwidth of the TD tracking differentiator is determined by the system dynamic requirements. IP control takes into account the requirements of overshoot and dynamic response by selecting different coefficients. The dynamic and static performance of the system is improved by the speed feedforward coefficient; 3. The present invention is closely integrated with the structural parameters of the servo system, and the resonance characteristics can be obtained in the mechanical design stage of the servo system. At the same time, the dynamic response limit reached by the position closed-loop system can be predicted, providing a reference for mechanical design and controller parameter design. Description of the Drawings

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings. Among them: Figure 1 It is the implementation flowchart of the present invention in Embodiment 1; Figure 2 It is the simplified model of the permanent magnet synchronous motor system; Figure 3 It is the system control schematic diagram; Figure 4 It is the disturbance observer block diagram. Detailed Embodiments

[0018] To make the above objects, features, and advantages of the present invention more obvious and understandable, the detailed embodiments of the present invention will be described below with reference to the drawings of the specification.

[0019] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0020] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that can be included in at least one implementation manner of the present invention. The "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that excludes other embodiments.

[0021] Embodiment 1 Refer to Figures 1 to 4 , which is the first embodiment of the present invention. This embodiment provides a method for suppressing the structural resonance of a low-stiffness and large-load permanent magnet synchronous motor flexible system, aiming to improve the control accuracy and dynamic response ability of the load end of the permanent magnet synchronous motor flexible system and suppress the structural resonance, including the following steps: Step S1: Use a tracking differentiator to perform path planning on the position command signal to obtain the planned command and the differential signal of the command.

[0022] Specifically, adopt a TD tracking differentiator to perform transition processing on the position signal to obtain the planned and the differential signal of the command , which can be specifically reflected by the following formula: ; ; ; wherein, is the position command, and are the planned commands at the (k + 1)-th and k-th moments respectively, and are the command differential signals at the (k + 1)-th and k-th moments respectively, and h is the calculation step size.

[0023] Exemplarily, the above parameters adopt the fastest synthesis function , and can be specifically expressed as: ; ; ; ; ; ; ; ; ; wherein, r is the tracking acceleration factor, which determines the bandwidth of the tracking differentiator, , where is the position loop bandwidth; is the filtering factor, , generally taking an integer multiple of the step size, and the larger the value, the better the filtering effect; is the sign function.

[0024] Since filtering will cause a certain phase lag in the planned , therefore, the phase compensation processing of the command can be reflected by the following formula: ; wherein, n is an integer.

[0025] It should be noted that in this step, the input position signal is dynamically filtered by setting a TD tracking differentiator to achieve smooth transition of the original command signal and extraction of differential information. The TD differentiator is constructed using the fastest synthesis function, and the tracking acceleration factor and filtering factor are set so that the planned trajectory of the output position signal is continuous and smooth, and carries speed and acceleration estimation information that can be used in subsequent control links. Considering that filtering may introduce phase lag, this step also designs a phase compensation strategy to reduce the planning error, and finally outputs the reference command and its differential signal for closed-loop control, effectively improving the controllability and real-time performance of the system response feedforward channel.

[0026] Step S2: Use the planned command to participate in the position loop closed-loop control, and at the same time adopt speed feedforward control in the speed loop to improve the dynamic response.

[0027] Specifically, it can be reflected by the following formula: The position loop closed-loop control formula is as follows: ; In the formula, is the position feedback; is the speed command; is the amplification coefficient, .

[0028] The speed feedforward formula is as follows: ; In the formula, is the feedforward compensation coefficient, which takes values in the interval [0,1], the larger it is, the better the phase compensation effect, generally ; It should be noted that after obtaining the path planning signal, this step constructs a speed feedforward channel based on its derivative term, and compensates for the response lag of the system through a predictive control strategy. Specifically, the speed feedforward signal is superimposed on the output of the position closed-loop control to generate a more accurate torque input command, thereby reducing the dynamic lag caused by the system inertia. The speed feedforward compensation coefficient can be adjusted between [0,1] to balance the dynamic overshoot and response speed of the system. This step significantly improves the system's response ability to rapid target changes, and enhances the tracking accuracy and anti-disturbance ability.

[0029] Step S3: Establish a disturbance observer to obtain the system wheelbase for subsequent pole placement to improve the system damping.

[0030] Specifically, the disturbance observer specifically refers to Figure 4 as shown, from the motor electromagnetic torque equation , the disturbance observer formula is obtained as follows: ; In the formula, is the actual wheelbase; is the observed wheelbase; is the speed feedback; is the moment of inertia of the motor and the transmission structure; is the damping coefficient, generally 0; is the filtering frequency, used to filter the influence of noise; Exemplarily, the above parameters for the motor electromagnetic torque can be reflected by the following formula: ; In the formula, is the torque coefficient; is the q-axis current feedback.

[0031] It should be noted that in this step, the electromagnetic torque equation of the motor is used to construct a disturbance observer to estimate the influence of the flexible structure vibration on the system wheelbase. The observer input includes the speed feedback signal and the motor output torque signal, and the filtering frequency parameter is designed to weaken the high-frequency noise interference. The core idea is to calculate the electromagnetic torque through the torque and current feedback , and combine the inertia model to estimate the disturbance influence, and output an observed wheelbase for wheelbase error compensation . This compensation mechanism significantly improves the stability and control accuracy of the system under the action of the flexible structure.

[0032] Step S4: Through IP control, perform pole placement on the system to suppress structural resonance.

[0033] Specifically, IP control is used for system pole placement to improve the system damping. Since IP control does not generate zeros, it can better suppress resonance, which can be specifically reflected by the following formula: ; ; In the formula, is the motor electromagnetic torque command; a takes values in the interval [0,1], generally a = 0.5. By selecting different values, the requirements of overshoot and dynamic response are taken into account. Increasing a improves the system resonance suppression ability and reduces overshoot; decreasing a improves the dynamic response of the system; and are the amplification coefficient and the integral coefficient respectively; k is the wheelbase compensation coefficient; Exemplarily, the above parameters can be specifically expressed as: ; In the formula, is axis current command; ; ; In the formula, is the moment of inertia of the motor and the transmission mechanism, is the system resonance frequency, , where K is the structural stiffness of the servo system, is the load mass.

[0034] ; In the formula, i is the total transmission ratio of the servo system.

[0035] It should be noted that, in order to suppress the structural resonance that may occur in the flexible system under low stiffness and large load, this step introduces a zero-free IP controller (proportional-integral control), and optimizes the closed-loop response of the system through pole placement. The proportional gain and the integral gain of the IP controller are set according to the system resonance frequency , the moment of inertia and the mechanical structure stiffness K, to ensure that the system has a high damping ratio, suppress the resonance peak, and at the same time achieve a balance between overshoot and response speed. By adjusting the controller parameters, the resonance frequency matching and dynamic characteristic optimization can also be realized, so as to ensure the stable operation of the system.

[0036] In summary, this method does not require the displacement, velocity or acceleration signals at the load end, nor does it require very accurate information such as the load resonance frequency, and can still achieve good resonance suppression effect, and has good dynamic response, reducing the demand for hardware; in addition, based on the system control schematic diagram, the present invention can be used for fast system simulation, and at the same time, this scheme is convenient for parameter adjustment, and determines the bandwidth of the TD tracking differentiator according to the system dynamic requirements. The IP control takes into account the requirements of overshoot and dynamic response by selecting different coefficients. Through the velocity feedforward coefficient, the dynamic and static performance of the system is improved. And it is closely combined with the structural parameters of the servo system, and the resonance characteristics can be obtained at the mechanical design stage of the servo system, and at the same time, the dynamic response limit that the position closed-loop system can reach can be predicted, providing a reference for mechanical design and controller parameter design.

[0037] Embodiment 2 Embodiment 2 is the second embodiment of the present invention. The difference between this embodiment and the first embodiment is that it also provides a structural resonance suppression system for a flexible system of a permanent magnet synchronous motor with low stiffness and large load, including: A path planning module, configured to perform filtering processing and path planning on the position command signal by using a tracking differentiator, and generate a continuous and smooth reference position signal, velocity signal and acceleration signal; The feedforward and feedback control module is used to perform closed-loop control of the position loop and speed feedforward compensation based on the reference signal generated by the path planning module, so as to improve the dynamic response and tracking accuracy of the system; The disturbance observation module is used to estimate the vibration disturbance of the flexible structure in real time according to the motor operation parameters and output a disturbance compensation signal; The pole placement and IP control module is used to perform pole placement on the system by using an IP controller according to the output result of the disturbance observation module, suppress resonance and improve the system damping.

[0038] This embodiment also provides a computer device, which is applicable to a situation of a method for suppressing the structural resonance of a flexible system of a low-rigidity large-load permanent magnet synchronous motor, including: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement a method for suppressing the structural resonance of a flexible system of a low-rigidity large-load permanent magnet synchronous motor as proposed in the above embodiment.

[0039] This computer device can be a terminal. The computer device includes a processor, a memory, a communication interface, a display screen, and an input device connected through a system bus. Among them, the processor of this computer device is used to provide computing and control capabilities. The memory of this computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of this computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, a carrier network, NFC (near field communication) or other technologies. The display screen of this computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of this computer device can be a touch layer covered on the display screen, or a button, a trackball or a touchpad set on the shell of the computer device, or an external keyboard, a touchpad or a mouse, etc.

[0040] This embodiment also provides a storage medium, on which a computer program is stored. When the program is executed by a processor, it implements the method for suppressing the resonance of a flexible system structure of a low-stiffness and large-load permanent magnet synchronous motor as proposed in the above embodiment. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM for short), electrically erasable programmable read-only memory (EEPROM for short), erasable programmable read-only memory (EPROM for short), programmable read-only memory (PROM for short), read-only memory (ROM for short), magnetic memory, flash memory, magnetic disk or optical disc.

[0041] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A method for suppressing structural resonance of a low-rigidity, high-load permanent magnet synchronous motor flexible system, characterized in that: include: S1, tracking differentiator path planning: by setting the TD tracking differentiator to dynamically filter the input position signal, a smooth planning instruction and its differential signal are generated; S2, speed feedforward control: Based on the planned command differential signal, the speed feedforward control method is used to introduce feedforward compensation in the position closed loop; S3, disturbance observer establishment and compensation: According to the electromagnetic torque equation of the motor, a disturbance observer is constructed to estimate the actual wheelbase of the system in real time and perform disturbance compensation; S4, IP controller pole configuration: Based on the system resonance characteristics, the IP control method is used for pole configuration, and the proportional gain and integral gain are set to suppress structural resonance and optimize the closed-loop response.

2. The method for suppressing structural resonance of a low-rigidity, high-load permanent magnet synchronous motor flexible system according to claim 1, characterized in that: The TD tracking differentiator is based on the fastest comprehensive function and combines the set tracking acceleration factor and filtering factor to achieve smooth transition and differential output of the position signal, and reduce the lag error introduced in the planning process through phase compensation.

3. The method for suppressing structural resonance of a low-rigidity, high-load permanent magnet synchronous motor flexible system according to claim 2, characterized in that: The speed feedforward control calculates a feedforward torque signal according to the planned speed signal, and superimposes the feedforward torque with the feedback control torque to compensate for the hysteresis caused by the rotational inertia of the motor.

4. The method for suppressing structural resonance of a low-rigidity, high-load permanent magnet synchronous motor flexible system according to claim 3, characterized in that: The disturbance observer estimates disturbance based on the feedback speed signal and the motor output torque signal. The observer uses a filter frequency parameter to suppress high-frequency noise. The output observation wheelbase is used to compensate for the low stiffness effect caused by the flexible structure.

5. The method for suppressing structural resonance of a low-rigidity, high-load permanent magnet synchronous motor flexible system according to claim 4, characterized in that: The electromagnetic torque of the motor in the disturbance observer is obtained by shaft current feedback calculation, and the torque coefficient is multiplied by the current signal to obtain an electromagnetic torque signal to participate in the disturbance observation operation.

6. The method for suppressing structural resonance of a low-rigidity, high-load permanent magnet synchronous motor flexible system according to claim 5, characterized in that: The proportional gain and integral gain of the IP controller are determined by calculating the load resonant frequency, system moment of inertia and mechanical structure stiffness parameters. The pole configuration gives priority to improving the system damping ratio and reducing the resonance peak amplitude, and makes a trade-off between overshoot and response speed according to different application requirements.

7. The method for suppressing structural resonance of a low-rigidity, high-load permanent magnet synchronous motor flexible system according to claim 6, characterized in that: The resonant frequency is calculated based on the servo system structural stiffness and load mass, specifically: Determine, where K is the structural stiffness of the servo system, The load mass is calculated and the resonance characteristics are corrected according to the total transmission ratio of the servo system to guide the parameter setting of the IP controller.

8. A low-rigidity and high-load permanent magnet synchronous motor flexible system structural resonance suppression system, based on the low-rigidity and high-load permanent magnet synchronous motor flexible system structural resonance suppression method according to any one of claims 1 to 7, characterized in that: include, A path planning module, used for filtering and path planning the position command signal using a tracking differentiator; A feedforward and feedback control module, used for performing position loop closed-loop control and speed feedforward compensation based on the reference signal generated by the path planning module; The disturbance observation module is used to estimate the vibration disturbance of the flexible structure in real time according to the motor operating parameters and output a disturbance compensation signal; The pole configuration and IP control module is used to configure the poles of the system using an IP controller based on the output results of the disturbance observation module.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method for suppressing structural resonance of a flexible system of a low-rigidity and high-load permanent magnet synchronous motor as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for suppressing structural resonance of a flexible system of a low-rigidity and high-load permanent magnet synchronous motor as described in any one of claims 1 to 7 are implemented.

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