A servo motor control method and device, electronic equipment and storage medium

Abstract

This invention discloses a servo motor control method, device, electronic device, and storage medium. The method mainly includes the following steps: establishing a target position coordinate system DQ based on the target position. * , compare the target location with D * Shaft coincidence; D calculated based on encoder feedback position * The angle θ between the shaft and the D-axis of the rotor coordinate system DQ; combining the two coordinate systems DQ * And DQ, select an appropriate direct-axis current Id * Calculate the electromagnetic torque Te output by the servo motor; when the load increases, set the first control strategy of Id*; when the speed increases, set Id*. * The second control strategy involves increasing the servo loop's immunity by modifying the direct-axis current Id*, without increasing the regulator's gain or adding an additional disturbance observer. This enables high-rigidity control of the servo motor in applications requiring low speed and high stability.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, and in particular to a servo motor control method, device, electronic device, and storage medium. Background Technology

[0002] In current servo drive control solutions for permanent magnet synchronous motors, most employ space vector algorithms, and the control block diagram is as follows: Figure 1 As shown, in the rotating coordinate system DQ, the stator current is divided into direct-axis current Id and quadrature-axis current Iq, which are orthogonal vectors. The direction of Id coincides with the direction of the permanent magnet flux linkage of the permanent magnet motor. The control strategy is usually Id = 0, and Id < 0 during high-speed field weakening of the motor. The direction of Iq is perpendicular to the flux linkage direction, and the magnitude of Iq is proportional to the electromagnetic torque output by the servo motor.

[0003] Output electromagnetic torque:

[0004] When the control strategy of Id=0 is adopted, Equation 1 simplifies to:

[0005] In the formula, the parameters are defined as follows: Id: direct-axis current; Iq: quadrature-axis current; Te: electromagnetic torque; Pn: number of motor stage pairs; ψ m Motor flux linkage.

[0006] Control block diagram as follows Figure 2 As shown, the current loop is simplified to a transfer function of 1:

[0007] Transfer function of relative velocity of load disturbance:

[0008] In the formula, the parameters are defined as follows: J: motor inertia; K p : Velocity loop proportional gain; K i : Integral coefficient of the velocity loop.

[0009] Besides high precision and high response, noise immunity is also an important performance indicator for servo motor systems. As can be seen from Equation 4, there are two main ways to reduce errors:

[0010] One approach is to increase the proportional gain K of the speed loop PI regulator. p This method is feasible, but it has a drawback: K p The increase of K will also increase the sampling error of the feedback loop and reduce the phase margin of the entire loop. According to the Nyquist theorem, K p If the increase reaches a certain level, it will cause instability in the entire system.

[0011] Secondly, by using a disturbance observer to monitor changes in load torque and then providing torque current compensation in the current loop, this method does not reduce system stability. However, due to the bandwidth limitation of the disturbance observer, the compensation has a lag and cannot achieve the desired effect. Summary of the Invention

[0012] To address the aforementioned technical problems, this invention proposes a servo motor control method, device, electronic equipment, and storage medium. This control method does not require increasing the gain of the regulator or adding an additional disturbance observer; instead, it controls the direct-axis current Id by changing the direct-axis current. * The size of the variable is adjusted to increase the immunity of the servo loop. This enables high-rigidity control in applications requiring low speed and high stability.

[0013] According to a first aspect of the present invention, a servo motor control method is provided, comprising the following steps:

[0014] The servo driver receives position commands and determines the target position;

[0015] Establish the target position coordinate system DQ based on the target position. * , compare the target location with D * Axis coincidence;

[0016] Calculate D based on encoder feedback position * The angle θ between the shaft and the D-axis of the rotor coordinate system DQ;

[0017] Combining two coordinate systems DQ * And DQ, set an appropriate direct-axis current Id * Calculate the electromagnetic torque Te output by the servo motor:

[0018]

[0019] In the formula, Iq is the quadrature-axis current in the rotor coordinate system DQ, and Id is the quadrature-axis current. * The target position coordinate system is DQ * The direct-axis current, Pn is the number of motor stage pairs, ψ m Ld represents the motor flux linkage, and Lq represents the inductance of the D-axis and Q-axis, respectively.

[0020] Furthermore, the servo motor control method further includes:

[0021] When the load T L As the value of Iq increases, the output current of the driver is approximately I ≈ (Iq) 2 +(Id * ) 2 ) 1 / 2 Let Id * Given a value of C, the driver current output limit is I.lim ;

[0022] According to Iq, C, and I lim Size relationship, set Id * The first control strategy.

[0023] Furthermore, the first control strategy is as follows:

[0024] Id * =C; when Iq≤(I lim 2 -C 2 ) 1 / 2 ;

[0025] Id * =(I lim 2 -Iq 2 ) 1 / 2 When Iq > (I lim 2 -C 2 ) 1 / 2 .

[0026] Furthermore, the servo motor control method further includes:

[0027] As the servo motor speed increases, the second control strategy of Id* is set according to the servo motor speed ω.

[0028] Furthermore, the second control strategy is as follows:

[0029] Id * =C; when ω≤V1;

[0030] Id * =(V2-ω)×C / (V2-V1); when V1<ω<V2;

[0031] Id * =0; when V2≤ω;

[0032] In the formula, C represents Id. * Given a size, V1 is the set first threshold for rotational speed ω, and V2 is the set second threshold for rotational speed ω.

[0033] According to a second aspect of the present invention, a servo motor control device is provided, comprising the following modules:

[0034] The target position determination module is used to determine the target position based on the position command received by the servo driver;

[0035] The DQ* coordinate system establishment module is used to establish the target position coordinate system DQ based on the target position. * , compare the target location with D* Axis coincidence;

[0036] The included angle calculation module is used to calculate D based on the encoder feedback position. * The angle θ between the shaft and the D-axis of the rotor coordinate system DQ;

[0037] The electromagnetic torque calculation module is used to integrate two coordinate systems, DQ. * And DQ, set an appropriate direct-axis current Id * Calculate the electromagnetic torque Te output by the servo motor:

[0038]

[0039] In the formula, Iq is the quadrature-axis current in the rotor coordinate system DQ, and Id is the quadrature-axis current. * The target position coordinate system is DQ * The direct-axis current, Pn is the number of motor stage pairs, ψ m Ld represents the motor flux linkage, and Lq represents the inductance of the D-axis and Q-axis, respectively.

[0040] Furthermore, it also includes:

[0041] The first control strategy setting module is used when the load T L As the value of Iq increases, the output current of the driver is approximately I ≈ (Iq) 2 +(Id * ) 2 ) 1 / 2 Let Id * Given a value of C, the driver current output limit is I. lim According to Iq, C and I lim Size relationship, set Id * The first control strategy.

[0042] Furthermore, it also includes:

[0043] The second control strategy setting module is used to set the second control strategy of Id* according to the magnitude of the servo motor speed ω when the servo motor speed increases.

[0044] According to a third aspect of the present invention, an electronic device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the servo motor control method.

[0045] According to a fourth aspect of the invention, the invention also provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the servo motor control method described above.

[0046] The technical solution provided by this invention has the following beneficial effects:

[0047] 1. This invention constructs a coordinate system DQ* based on the target position and controls the D-axis current Id* under this coordinate system to realize a control strategy that enhances the rigidity of the servo motor.

[0048] 2. This invention improves system stability by providing an Id* current in steady state. Since the proportional gain of the velocity loop is not increased, the system's phase margin is not reduced, the system loop stability remains unchanged, and the rigidity is enhanced.

[0049] 3. This invention also takes into account that as the load increases, since the given Id* occupies a portion of the current, a corresponding Id* setting strategy is designed in order to achieve maximum torque output.

[0050] 4. This invention also takes into account the effect of increased rotational speed on Id. * A given positive value will increase the back EMF constant. To achieve maximum speed output, a corresponding Id is designed. * The given strategy. Attached Figure Description

[0051] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0052] Figure 1 Here is a speed control block diagram;

[0053] Figure 2 A simplified diagram of the velocity loop;

[0054] Figure 3 This is an overall flowchart of a servo motor control method according to an embodiment of the present invention;

[0055] Figure 4 The target position coordinate system in this embodiment of the invention is DQ*;

[0056] Figure 5 This is an improved velocity loop diagram in an embodiment of the present invention;

[0057] Figure 6 This is a schematic diagram of the structure of a servo motor control device according to an embodiment of the present invention;

[0058] Figure 7 This is a schematic diagram of the physical structure of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0059] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0060] In this embodiment, to increase the immunity of the servo motor system without sacrificing system stability, a new servo motor control method is adopted. This control method uses the target position coordinate system Id * The strategy of setting the torque to >0 increases the electromagnetic torque in steady state, thereby improving system stability. Furthermore, it smoothly exits torque compensation as the speed increases, without affecting the motor's maximum speed.

[0061] refer to Figure 3 The servo motor control method specifically includes the following steps:

[0062] S1: The servo driver receives the position command and determines the target position;

[0063] S2: Establish the target position coordinate system DQ based on the target position. * , compare the target location with D * Axis coincidence; Target position coordinate system DQ * like Figure 4 As shown;

[0064] S3: Calculate D based on encoder feedback position * The angle θ between the shaft and the D-axis of the rotor coordinate system DQ is detailed in the reference [reference needed]. Figure 4 ;

[0065] S4: Combining two coordinate systems DQ * And DQ, set an appropriate direct-axis current Id * Calculate the electromagnetic torque Te output by the servo motor:

[0066]

[0067] In the formula, Iq is the quadrature-axis current in the rotor coordinate system DQ, and Id is the quadrature-axis current. * The target position coordinate system is DQ * The direct-axis current, Pn is the number of motor stage pairs, ψ m Ld and Lq represent the inductance of the motor magnetic flux and the inductance of the D-axis and Q-axis, respectively.

[0068] S5: When the load T L As the value of Iq increases, the output current of the driver is approximately I ≈ (Iq) 2 +(Id * ) 2 ) 1 / 2 Let Id * Given a value of C, the driver current output limit is I. lim According to Iq, C, and I lim Size relationship, set Id * The first control strategy is as follows:

[0069] Id* =C; when Iq≤(I lim 2 -C 2 ) 1 / 2 ;

[0070] Id * =(I lim 2 -Iq 2 ) 1 / 2 When Iq > (I lim 2 -C 2 ) 1 / 2 ;

[0071] This way, the maximum torque output is not affected, and the system rigidity is increased under medium and low load conditions.

[0072] In this embodiment, let C = I N / 2,I lim =2I N ;I N This is the rated current of the motor.

[0073] Id * =I N / 2,;When Iq≤(4I N 2 -I N 2 / 4) 1 / 2 ≈1.94I N ;

[0074] Id * =(4I N 2 -Iq 2 ) 1 / 2 When Iq > (I lim 2 -C 2 ) 1 / 2 ≈1.94I N .

[0075] S6: Considering that as the rotational speed ω increases, Id * A value greater than 0 will increase the back EMF time constant of the motor, thus reducing the maximum speed the motor can reach. Therefore, when ω increases to a certain speed, Id needs to be adjusted. * The value will gradually decrease to 0 to ensure the motor's maximum output speed. Therefore, based on the servo motor's speed ω, the second control strategy for Id* is set as follows:

[0076] Id * =C; when ω≤V1;

[0077] Id *=(V2-ω)×C / (V2-V1); when V1<ω<V2;

[0078] Id * =0; when V2≤ω;

[0079] In the formula, C represents Id. * Given a size, V1 is the set first threshold for rotational speed ω, and V2 is the set second threshold for rotational speed ω.

[0080] In this embodiment, let V1 = V N / 2, V2=V N V N Rated speed of the motor.

[0081] Id * =I N / 2; when ω≤V N / 2;

[0082] Id * =(V N -ω)×I N / V N When V N / 2<ω<V N ;

[0083] Id * =0; when V N ≤ω.

[0084] The speed loop improvement diagram corresponding to this control method is as follows: Figure 5 As shown, the rigidity of the system can be improved in the following three ways:

[0085] 1. The first part of Formula 5 make Due to Id * The effect of this is that, and generally Ld>Lq, therefore (Ld-Lq)Id * ×cosθ>0Kt * >Kt, it can be seen that the torque provided by the same Iq increases.

[0086] Therefore, by giving an Id * The method of >0 improves torque output and system immunity.

[0087] 2. In the second part of Equation 5, the electromagnetic torque is increased by Id. * Provides torque component The system is subjected to load T L When disturbed, θ increases, this component increases, naturally forming negative feedback, which partially cancels out T. L This reduces the impact on the rotational speed ω and improves the anti-interference capability.

[0088] 3. External disturbance, according to Equation 4, error transfer function: Under the new control method, Kt becomes Kt * The new error transfer function becomes:

[0089]

[0090] As can be seen from Equation 6, when kp remains constant, the denominator of Equation 6 is greater than that of Equation 4. The disturbance of load torque has a smaller impact on the speed, thus improving the system's disturbance rejection capability.

[0091] The servo motor control device provided by the present invention is described below. The servo motor control device described below can be referred to in correspondence with the servo motor control method described above.

[0092] like Figure 6 As shown, a servo motor control device includes the following modules:

[0093] Target position determination module 01 is used to determine the target position according to the position command received by the servo driver. Coordinate system establishment module 02 is used to establish the target position coordinate system DQ based on the target position. * , compare the target location with D * Axis coincidence;

[0094] Angle calculation module 03 is used to calculate D based on the encoder feedback position. * The angle θ between the shaft and the D-axis of the rotor coordinate system DQ;

[0095] Electromagnetic torque calculation module 04 is used to integrate two coordinate systems DQ. * And DQ, set an appropriate direct-axis current Id * Calculate the electromagnetic torque Te output by the servo motor:

[0096]

[0097] In the formula, Iq is the quadrature-axis current in the rotor coordinate system DQ, and Id is the quadrature-axis current. * The target position coordinate system is DQ * The direct-axis current, Pn is the number of motor stage pairs, ψ m Ld and Lq represent the inductance of the motor magnetic flux and the inductance of the D-axis and Q-axis, respectively.

[0098] The first control strategy setting module 05 is used to set the load T when... L As the value of Iq increases, the output current of the driver is approximately I ≈ (Iq) 2 +(Id * ) 2 ) 1 / 2 Let Id *Given a value of C, the driver current output limit is I. lim According to Iq, C and I lim Size relationship, set Id * The first control strategy.

[0099] The second control strategy setting module 06 is used to set the second control strategy of Id* according to the magnitude of the servo motor speed ω when the servo motor speed increases.

[0100] Based on the above device, the first control strategy is set as follows:

[0101] Id * =C; when Iq≤(I lim 2 -C 2 ) 1 / 2 ;

[0102] Id * =(I lim 2 -Iq 2 ) 1 / 2 When Iq > (I lim 2 -C 2 ) 1 / 2 .

[0103] Based on the above device, the second control strategy is set as follows:

[0104] Id * =C; when ω≤V1;

[0105] Id * =(V2-ω)×C / (V2-V1); when V1<ω<V2;

[0106] Id * =0; when V2≤ω;

[0107] In the formula, C represents Id. * Given a size, V1 is the set first threshold for rotational speed ω, and V2 is the set second threshold for rotational speed ω.

[0108] The device changes the direct-axis current Id * The size of the variable is adjusted to increase the immunity of the servo loop. No increase in regulator gain or additional disturbance observer is required, enabling high-rigidity control of servo motors in applications requiring low speed and high stability.

[0109] like Figure 7The diagram illustrates the physical structure of an electronic device, which may include a processor 610, a communication interface 620, a memory 630, and a communication bus 640. The processor 610, communication interface 620, and memory 630 communicate with each other via the communication bus 640. The processor 610 can call logical instructions from the memory 630 to execute the steps of a servo motor control method, specifically including: establishing a target position coordinate system DQ based on the target position. * , compare the target location with D * Shaft coincidence; D is calculated based on encoder feedback position. * The angle θ between the shaft and the D-axis of the rotor coordinate system DQ; combining the two coordinate systems DQ * And DQ, select an appropriate direct-axis current Id * Calculate the electromagnetic torque Te output by the servo motor; when the load increases, set the first control strategy of Id*; when the speed increases, set Id*. * The second control strategy.

[0110] Furthermore, the logical instructions in the aforementioned memory 630 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0111] In another aspect, embodiments of the present invention also provide a storage medium storing a computer program, which, when executed by a processor, implements the steps of a servo motor control method, specifically including: establishing a target position coordinate system DQ based on the target position. * , compare the target location with D * Shaft coincidence; D is calculated based on encoder feedback position. * The angle θ between the shaft and the D-axis of the rotor coordinate system DQ; combining the two coordinate systems DQ * And DQ, select an appropriate direct-axis current Id *Calculate the electromagnetic torque Te output by the servo motor; when the load increases, set the first control strategy of Id*; when the speed increases, set Id*. * The second control strategy.

[0112] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0113] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. In the unit claims listing several devices, several of these devices may be embodied by the same hardware item. The use of the terms first, second, and third, etc., does not indicate any order and can be interpreted as identifiers.

[0114] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method of controlling a servo motor, characterized by, The method comprises the following steps: The servo driver receives a position instruction and determines a target position; According to the target position, a target position coordinate system DQ is established * The target position is coincided with the D * axis D is calculated from the encoder feedback position * the angle θ between the D-axis of the shaft and rotor coordinate system DQ; DQ * and DQ, set appropriate direct-axis current Id * , calculate the electromagnetic torque Te output by the servo motor where Iq is the quadrature axis current in the rotor coordinate system DQ, Id * is the direct axis current in the target position coordinate system DQ * , Pn is the number of motor pole pairs, ψ m is the motor flux, and Ld and Lq represent the inductances of the D-axis and Q-axis, respectively.

2. The servo motor control method of claim 1, wherein Further comprising: When the load T L increases, the value of Iq increases, and the output current I of the driver becomes I 2 ≈ (Iq * + Id 2 ) 1 / 2 , assuming that the given size of Id * is C, and the limit value of the output current of the driver is I lim , According to the size relationship of Iq, C and I lim , the first control strategy of Id * is set.

3. The method of claim 2, wherein The first control strategy is as follows: Id * = C; when Iq < (I lim 2 - C 2 ) 1 / 2 ; Id * = (I lim 2 -Iq 2 ) 1 / 2 ; when Iq > (I lim 2 -C 2 ) 1 / 2 .

4. The method of claim 1, wherein Further comprising: When the servo motor speed increases, a second control strategy of Id* is set according to the size of the servo motor speed ω.

5. The method of claim 4, wherein, The second control strategy is as follows: Id * = C; when ω < V1; Id * = (V2 - ω) x C / (V2 - V1); When V1 < ω < V2; Id * = 0; when V2≤ ω; where C is Id * of a given size, V1 is a set rotational speed ω first threshold value, and V2 is a set rotational speed ω second threshold value.

6. A servo motor control device for implementing the method according to any one of claims 1 to 5, characterized in that The method comprises the following modules: A target position determination module is configured to determine a target position according to a position instruction received by the servo driver; The DQ coordinate system establishing module is configured to establish a target position coordinate system DQ according to the target position * The target position is matched with the D * The axes are coincident; An angle calculation module is configured to calculate D * an angle θ between the D-axis of the shaft and rotor coordinate system DQ; An electromagnetic torque calculation module is used to synthesize the two coordinate systems DQ * and DQ, set appropriate direct axis current Id * , calculate the electromagnetic torque Te output by the servo motor: where Iq is the quadrature axis current in the rotor coordinate system DQ, Id * is the direct axis current in the target position coordinate system DQ * Pn is the motor order, ψ m is the motor flux, and Ld, Lq represent the inductances of the D and Q axes, respectively.

7. The servo motor control device of claim 6, wherein Further comprising: The first control strategy setting module is configured to set a first control strategy of Id L when the load T 2 increases, the value of Iq increases, and the output current I of the driver is approximately equal to (Iq * +(Id 2 ) 1 / 2 , where Id * is given a size C, and the output current limit value of the driver is I lim . According to the size relationship among Iq, C, and I lim , the first control strategy of Id * is set.

8. The servo motor control device of claim 6, wherein Further comprising: A second control strategy setting module is configured to set a second control strategy of Id* according to the size of the servo motor speed ω when the servo motor speed increases.

9. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the program to implement the steps of the servo motor control method according to any one of claims 1-5.

10. A storage medium having stored thereon a computer program, characterized in that The computer program is executed by the processor to implement the steps of the servo motor control method according to any one of claims 1-5.

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