Phase searching method, controller and servo system

Abstract

The application discloses a phase searching method, a controller and a servo system. The method comprises the following steps: inputting a given current into a motor of the servo system, increasing the given current amplitude of the motor according to a preset current increasing step to perform a phase searching action, and detecting the motion distance of a motor rotor of the motor in the phase searching action; when the motion distance reaches a preset distance, the input of the given current is stopped, the current motion direction of the motor rotor in the phase searching action is determined, the target motion direction and the target current electric angle are determined according to the current motion direction and a preset limit direction; the direction of the current electric angle of the given current is adjusted towards the target motion direction, and the given current is configured as the target current electric angle to enter the next phase searching action; and when the given current amplitude reaches a preset current amplitude for a preset number of times, the phase searching is ended. In the embodiment of the application, the judgment of the limit direction is added in the phase searching process, so that the accuracy of the phase searching under different working conditions can be improved.

Description

Technical Field

[0001] This application relates to the field of motor drive technology, and in particular to a phase-finding method, controller and servo system. Background Technology

[0002] Servo control systems, with their advantages of high precision, high efficiency, and fast dynamic response, are widely used in various fields of modern industry. Servo control systems often employ field-oriented control (FOC) strategies to achieve precise motor control. This control strategy requires detecting the rotor position to achieve accurate field orientation. In motors with incremental encoders, since the initial electrical angle of the rotor is unknown, an accurate initial electrical angle must be obtained before each start-up; this process is called phase finding. If the phase finding result is inaccurate, it may lead to reduced motor efficiency or even motor runaway.

[0003] However, current phase-finding methods cannot control the direction of motor movement, making them unsuitable for applications with positional constraints. Furthermore, during phase-finding, hard-limit motors may stall, which could lead to a false positive of successful phase finding and reduce accuracy. Summary of the Invention

[0004] This application provides a phase-finding method, controller, and servo system. By incorporating a direction restriction judgment during the phase-finding process, the accuracy of phase-finding under different operating conditions can be improved.

[0005] In a first aspect, embodiments of this application provide a phase-finding method applied to a servo system, the method comprising: A given current is supplied to the motor of the servo system, and the amplitude of the given current of the motor is increased by a preset current increment step to perform a phase-finding action, and the movement distance of the motor rotor during this phase-finding action is detected. When the movement distance reaches the preset distance, the given current is stopped, the current movement direction of the motor rotor in this phase-finding action is determined, and the target movement direction and target current electrical angle are determined according to the current movement direction and the preset limiting direction. Adjust the direction of the current electrical angle of the given current toward the target direction of movement, and configure the given current to the target current electrical angle to enter the next phase-finding action; The phase search ends when the given current amplitude reaches the preset current amplitude a preset number of times.

[0006] The phase-finding method according to the first aspect of this application has at least the following beneficial effects: First, a given current is supplied to the motor of the servo system, and the amplitude of the given current of the motor is increased by a preset current increment step to perform a phase-finding action. Simultaneously, the movement distance of the motor rotor during this phase-finding action is detected in real time, i.e., real-time detection of the actual distance of the motor rotor is achieved. When the movement distance reaches a preset distance, the supplied current is stopped to prevent the motor rotor from exceeding the predetermined position and avoid overshoot. At the same time, the current movement direction of the motor rotor during this phase-finding action is determined, and the target movement direction and target current electrical angle are determined based on the current movement direction and the preset limiting direction. This allows for the inclusion of direction constraint judgment during phase finding, facilitating subsequent adjustment of the current electrical angle under positional constraints. The current electrical angle of the given current is then adjusted towards the target motion direction, and the given current is configured to the target current electrical angle to proceed to the next phase finding action. This achieves phase finding under the current operating parameters, enabling precise adjustment of the current electrical angle under positional constraints, thus improving the accuracy of phase finding. The entire phase finding process ends when the given current amplitude reaches the preset current amplitude a preset number of times. This allows for phase finding of the motor rotor under positional constraints, improving the accuracy of phase finding under different operating conditions and further enhancing the reliability of the servo system.

[0007] In some embodiments of this application, before applying a given current to the motor, the method further includes: Record the initial position of the motor rotor in the servo system; After the phase search is completed, the method further includes: The motor rotor is displacement compensated based on the current angle after phase finding and the initial position.

[0008] In some embodiments of this application, determining the target motion direction and the target current electrical angle based on the current motion direction and the preset limiting direction includes: Determine the electrical angle adjustment value and historical movement direction of the previous phase-finding action, and determine the adjustment direction of the electrical angle adjustment value; If the current direction of motion is a preset restricted direction, the target direction of motion of the current electrical angle is determined as an unrestricted direction, and the electrical angle adjustment value is determined as the target current electrical angle, wherein the unrestricted direction is opposite to the restricted direction; If the current direction of motion is an unrestricted direction, the target direction of motion and the target current electrical angle are determined based on the historical direction of motion, the current direction of motion, and the adjustment direction.

[0009] In some embodiments of this application, determining the target motion direction and the target current electrical angle based on the historical motion direction, the current motion direction, and the adjustment direction includes: If the current direction of motion is the same as the historical direction of motion, the electrical angle adjustment value is determined as the target current electrical angle, and the target direction of motion is determined as the adjustment direction; If the current direction of motion is opposite to the historical direction of motion, the electrical angle adjustment value is reduced to obtain the target current electrical angle, and the target direction of motion is determined as the opposite direction of the adjustment direction.

[0010] In some embodiments of this application, the displacement compensation of the motor rotor based on the current electrical angle after phase finding and the initial position includes: The electrical angle of the current after phase finding is adjusted by a preset angle so that the electrical angle of the current coincides with the preset position; Determine the current position of the motor rotor, and adjust the given current based on the current position and the initial position; The motor rotor is displaced according to the adjusted given current.

[0011] In some embodiments of this application, adjusting the given current based on the current position and the initial position includes: If the current position is less than the initial position, increase the given current; If the current position is greater than the initial position, decrease the given current.

[0012] In some embodiments of this application, after performing displacement compensation on the motor rotor according to the adjusted given current, the method further includes: Detect the compensated movement distance of the motor rotor; When the compensated movement distance reaches the preset distance, the given current is stopped, and the compensated position of the motor rotor displacement after compensation is determined. The displacement compensation operation ends when the compensation position coincides with the initial position.

[0013] In some embodiments of this application, the method further includes: When the given current amplitude reaches the preset current amplitude for the first time, and the movement distance does not reach the preset distance, the given current is stopped, and the direction of the electrical angle of the given current is reversed.

[0014] Thirdly, embodiments of this application also provide a controller, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the phase-finding method as described in the first aspect.

[0015] Fourthly, embodiments of this application also provide a servo system, including the controller described in the second aspect.

[0016] Fifthly, embodiments of this application also provide a computer-readable storage medium storing computer-executable instructions for causing a computer to perform the phase-finding method as described in the first aspect.

[0017] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the description and the accompanying drawings. Attached Figure Description

[0018] The accompanying drawings are used to provide a further understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0019] Figure 1 This is a flowchart of a phase-finding method provided in one embodiment of this application; Figure 2 This is a flowchart of determining the target motion direction and the target current electrical angle provided in an embodiment of this application; Figure 3 This is a flowchart provided in an embodiment of the present application for determining the target motion direction and the target current electrical angle based on the historical motion direction, the current motion direction, and the adjustment direction; Figure 4 This is a flowchart of the displacement compensation of the motor rotor based on the current electrical angle and initial position after phase finding, provided in an embodiment of this application. Figure 5 This is a flowchart of adjusting a given current based on the current position and the initial position, provided in an embodiment of this application; Figure 6 This is a flowchart of a phase-finding method provided in another embodiment of this application; Figure 7 This is a flowchart of a phase-finding method provided in another embodiment of this application; Figure 8 This is a flowchart of a phase-finding method provided in another embodiment of this application; Figure 9 This is a flowchart of phase finding for a motor rotor provided as an example in this application; Figure 10 This is a flowchart of adjusting the electrical angle of the current provided in one example of this application; Figure 11This is a flowchart of displacement compensation for a motor rotor provided as an example in this application; Figure 12 This is a schematic diagram illustrating the comparison of current and electrical angle adjustments provided in an example of this application; Figure 13 This is a schematic diagram of a controller provided in one embodiment of this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various implementations. Simultaneously, the steps or actions described in the method description can be rearranged or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various orders in the specification and drawings are merely for the clear description of a particular embodiment and do not imply a mandatory order, unless otherwise stated that a particular order must be followed.

[0021] In the description of this application, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0022] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0023] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0024] Servo control systems, with their advantages of high precision, high efficiency, and fast dynamic response, are widely used in various fields of modern industry. Servo control systems often employ field-oriented control (FOC) strategies to achieve precise motor control. This control strategy requires detecting the rotor position to achieve accurate field orientation. In motors with incremental encoders, since the initial electrical angle of the rotor is unknown, an accurate initial electrical angle must be obtained before each start-up; this process is called phase finding. If the phase finding result is inaccurate, it may lead to reduced motor efficiency or even motor runaway.

[0025] The binary search method is a commonly used phase-finding method with advantages such as small displacement and low risk. Its specific implementation involves giving a rated current vector for a certain phase, and then adjusting the phase of the given current according to the motor's direction of motion using the binary search method until the motor stops moving after the given current is applied. At this point, the phase of the given current is the initial phase of the motor rotor.

[0026] However, current phase-finding methods cannot control the direction of motor movement, making them unsuitable for applications with positional constraints. Furthermore, during phase-finding, hard-limit motors may stall, which could lead to a false positive of successful phase finding and reduce accuracy.

[0027] Based on the above, this application provides a phase-finding method, controller, and servo system. First, a given current is supplied to the motor of the servo system, and the amplitude of the given current is increased by a preset step size to perform the phase-finding action. Simultaneously, the movement distance of the motor rotor during this phase-finding action is detected in real time, i.e., real-time detection of the actual distance of the motor rotor. When the movement distance reaches a preset distance, the supplied current is stopped to prevent the motor rotor from exceeding the predetermined position and avoid overshoot. At the same time, the current movement direction of the motor rotor during this phase-finding action is determined, and the target movement direction and target current angle are determined based on the current movement direction and the preset limiting direction. This allows for the inclusion of direction constraint judgment during phase finding, facilitating subsequent adjustment of the current electrical angle under positional constraints. The current electrical angle of the given current is then adjusted towards the target direction of movement, and the given current is configured to the target current electrical angle to proceed to the next phase finding action. This achieves phase finding under the current operating parameters, enabling precise adjustment of the current electrical angle under positional constraints, thus improving the accuracy of phase finding. The entire phase finding process ends when the given current amplitude reaches the preset current amplitude a preset number of times. This allows for phase finding of the motor rotor under positional constraints, improving the accuracy of phase finding under different operating conditions and further enhancing the reliability of the servo system.

[0028] The embodiments of this application will be further described below with reference to the accompanying drawings.

[0029] like Figure 1 As shown, Figure 1 This is a flowchart of a phase-finding method provided in one embodiment of this application. The phase-finding method in this embodiment includes, but is not limited to, steps S101 to S104.

[0030] In some embodiments, the phase-finding method of this application is applied to, but not limited to, a servo system. The servo system includes a motor rotor and has two orthogonal coordinate axes, the q-axis and the d-axis, which are perpendicular to each other. In vector control, the motor current is decomposed into components along the d-axis and q-axis. By precisely controlling these two components, precise control of the motor torque and speed can be achieved, thereby improving the dynamic performance and efficiency of the system.

[0031] Step S101: Apply a given current to the motor of the servo system, and increase the given current amplitude of the motor by a preset current increment step to perform phase-finding action, and detect the movement distance of the motor rotor during this phase-finding action.

[0032] In step S101 of some embodiments, a given current is supplied to the motor of the servo system, and the amplitude of the given current of the motor is increased by a preset current increment step to perform phase-finding action. By gradually increasing the given current amplitude, the movement of the motor rotor can be controlled more precisely, avoiding damage to the servo system caused by sudden large current surges. Furthermore, during the phase-finding process, the embodiments of this application will detect the movement distance of the motor rotor in real time during this phase-finding action, which is convenient for subsequent judgment on whether the motor rotor needs to continue to rotate, thereby improving the stability of the servo system.

[0033] It should be noted that the current increase step size in this application embodiment refers to the fixed amount by which the given current value of the motor increases each time it is adjusted. The current increase step size can be set according to the user's needs or the historical operating parameters of the servo system. This application embodiment does not impose any specific limitations.

[0034] It is worth noting that, in this embodiment of the application, before increasing the given current amplitude of the motor by a preset current increment step, an initial phase of the given current is set, and then the given current amplitude is increased based on the initial phase.

[0035] Step S102: When the movement distance reaches the preset distance, stop the given current, determine the current movement direction of the motor rotor in this phase-finding action, and determine the target movement direction and target current electrical angle based on the current movement direction and the preset limiting direction.

[0036] In step S102 of some embodiments, when the movement distance reaches the preset distance, it indicates that the motor rotor has reached the set maximum distance. If the motor rotor continues to rotate after reaching the predetermined angle, it may cause overshoot. At this time, it is necessary to remove the given current, that is, stop the given current from being supplied, so as to prevent overshoot and avoid damage to the motor due to overload. In this embodiment, the current movement direction of the motor rotor in this phase-finding action will also be determined, and the current movement direction of the motor rotor will be compared with the preset limiting direction to determine the target movement direction of the current electrical angle and the target current electrical angle, that is, to determine the adjustment direction and adjustment angle of the current electrical angle. This allows for more precise control of the motor rotor operation, ensuring that it moves in the predetermined direction, facilitating phase finding when there are position restrictions, and further maintaining the stability of the servo system.

[0037] It is worth noting that in the embodiments of this application, the target motion direction is the adjustment direction of the current electrical angle, and the limiting direction is the motion direction of the motor rotor that is set in advance. For example, the positive motion direction of the motor rotor is set as the limiting direction, or the negative motion direction of the motor rotor is set as the limiting direction.

[0038] It should be noted that the preset distance in this application embodiment is the maximum distance that the motor rotor can reach during a single phase search process. The preset distance can be set according to the user's needs or the historical operation parameters of the servo system. This application embodiment does not impose any specific limitations.

[0039] Step S103: Adjust the direction of the current electrical angle of the given current toward the target direction of motion, and configure the given current to the target current electrical angle to enter the next phase-finding action.

[0040] In step S103 of some embodiments, after determining the target motion direction and the target current electrical angle, the current electrical angle direction and angle of the given current can be adjusted according to the target motion direction and the target current electrical angle. Specifically, the current electrical angle direction of the given current is adjusted towards the target motion direction. For example, if the target motion direction is positive, the current electrical angle direction of the given current is adjusted in the positive direction; if the target motion direction is negative, the current electrical angle direction of the given current is adjusted in the negative direction. The given current is then configured to the target current electrical angle, that is, the current electrical angle is adjusted to the target current electrical angle to enter the next phase-finding operation, thereby enabling the next phase-finding operation to be entered according to the specified direction and angle.

[0041] Step S104: When the number of times the given current amplitude reaches the preset current amplitude is the preset number, the phase search ends.

[0042] In step S104 of some embodiments, since the given current amplitude of the motor is increased by a preset current increment step size in this embodiment, the given current amplitude may reach the preset current amplitude during the phase finding operation. When the number of times the given current amplitude reaches the preset current amplitude is a preset number, it proves that the phase finding result is correct and the phase finding operation can be terminated, thereby completing the entire phase finding process. By setting a preset number of times, misjudgment of the motor rotor stall is prevented, the accuracy of phase finding is improved, and phase finding errors are avoided.

[0043] It should be noted that the preset number of times and preset current amplitude in the embodiments of this application can be set according to the user's needs or the historical operating parameters of the servo system, and the embodiments of this application do not impose specific limitations.

[0044] Specifically, in this embodiment, the preset number of attempts is two. That is, if the given current amplitude reaches the preset current amplitude twice consecutively, it proves that the phase finding result is correct. If the given current amplitude reaches the preset current amplitude for the first time, it may be that the motor rotor has stalled, for example, the motor rotor has touched a wall or obstacle, etc. If the phase finding is stopped at this time, the phase finding result will be inaccurate. Therefore, this embodiment will continue to perform phase finding in reverse to improve the accuracy of the phase finding result.

[0045] In some embodiments, before applying a given current to the motor, the phase-finding method of this application also needs to record the initial position of the motor rotor in the servo system, that is, the initial physical position of the motor rotor, so as to compensate for the displacement generated during the phase-finding process in the subsequent displacement compensation stage.

[0046] In some embodiments, after the phase search is completed, since the actual displacement of the motor rotor generated during the phase search process may deviate from the theoretical displacement, the present application embodiments will adjust the actual displacement and the theoretical displacement. Specifically, the phase search method of the present application embodiments further includes: performing displacement compensation on the motor rotor according to the current electrical angle and initial position after phase search, thereby compensating for the displacement generated during the phase search process. Furthermore, by performing displacement compensation on the motor rotor, it is possible to determine whether the actual movement direction of the motor is consistent with the theoretical direction, thereby preventing the phase search result from converging to the S pole and causing the motor to run away, and reducing instability caused by control errors.

[0047] Reference Figure 2 , Figure 2 This is a flowchart of determining the target motion direction and target current electrical angle provided in the embodiments of this application. The method includes, but is not limited to, steps S201 to S203.

[0048] Step S201: Determine the electrical angle adjustment value and historical movement direction of the previous phase-finding action, and determine the adjustment direction of the electrical angle adjustment value.

[0049] In step S201 of some embodiments, the electrical angle adjustment value and historical movement direction of the previous phase-finding action are determined, that is, the movement direction of the motor rotor of the previous phase-finding action is determined, and the adjustment direction of the electrical angle adjustment value is determined, that is, whether the previous phase-finding action was a positive or negative direction for adjusting the current electrical angle.

[0050] Step S202: If the current direction of motion is a preset restricted direction, the target direction of motion of the current electrical angle is determined as an unrestricted direction, and the electrical angle adjustment value is determined as the target current electrical angle.

[0051] It should be noted that the unrestricted direction is opposite to the restricted direction.

[0052] Step S203: If the current direction of motion is an unrestricted direction, determine the target direction of motion and the target current angle based on the historical direction of motion, the current direction of motion, and the adjustment direction.

[0053] In steps S202 to S203 of some embodiments, during the process of determining the target motion direction and the target current electrical angle, this embodiment of the application will determine whether the current motion direction is consistent with the preset restriction direction. Specifically, the current motion direction is compared with the preset restriction direction. If the current motion direction is the preset restriction direction, the non-restricted direction opposite to the restriction direction is directly taken as the target motion direction, so that the next motion direction of the motor rotor is the non-restricted direction, and the electrical angle adjustment value of the previous phase-finding action is taken as the target current electrical angle, thereby restricting the displacement of the motor in the restriction direction during the phase-finding process, which is convenient for phase-finding when there is a position restriction. If the current motion direction is the non-restricted direction, the target motion direction and the target current electrical angle need to be determined according to the historical motion direction and adjustment direction of the previous phase-finding action and the current motion direction of the motor rotor, thereby enhancing the accuracy of the phase-finding result and improving the phase-finding efficiency.

[0054] It is worth noting that, in this embodiment of the application, after setting the restricted direction, if the direction of movement of the motor rotor is the restricted direction in each phase-finding action, the direction of movement of the motor rotor in the next phase-finding action will definitely be the non-restricted direction, thereby restricting the displacement of the motor in the restricted direction during the phase-finding process, which facilitates phase-finding when there are position restrictions.

[0055] Reference Figure 3 , Figure 3 This is a flowchart provided in the embodiments of this application for determining the target motion direction and the target current electrical angle based on the historical motion direction, the current motion direction and the adjustment direction. The method includes, but is not limited to, steps S301 to S302.

[0056] Step S301: If the current direction of motion is the same as the historical direction of motion, determine the electrical angle adjustment value as the target current electrical angle, and determine the target direction of motion as the adjustment direction.

[0057] In step S301 of some embodiments, during the process of determining the target motion direction and the target current electrical angle, firstly, the current motion direction and the historical motion direction are compared. If the current motion direction and the historical motion direction are the same, the electrical angle adjustment value of the previous phase-finding action can be directly determined as the target current electrical angle, and the target motion direction can be directly determined as the adjustment direction of the previous phase-finding action. For example, the electrical angle adjustment value of the previous phase-finding action is 45 degrees, and the adjustment direction is positive. If the motor rotor moves positively in the current phase-finding action, and the motor rotor also moves positively in the previous phase-finding action, then the current motion direction and the historical motion direction of the motor rotor are the same, both being positive. At this time, the target current electrical angle is 45 degrees, and the target motion direction is positive. Subsequently, the current electrical angle of the given current is adjusted by 45 degrees in the positive direction.

[0058] Step S302: If the current direction of motion is opposite to the historical direction of motion, reduce the electrical angle adjustment value to obtain the target current electrical angle, and determine the target direction of motion as the opposite direction of the adjustment direction.

[0059] In step S302 of some embodiments, if the current direction of motion is opposite to the historical direction of motion, it means that the current electrical angle adjustment has crossed the motor rotor, resulting in a change in the relative position direction of the current electrical angle and the motor rotor. If the electrical angle adjustment is too large, it may cause the motor rotor to move excessively and move away from the target position. At this time, it is necessary to reduce the electrical angle adjustment value to obtain the target current electrical angle, and determine the target direction of motion as the opposite direction of the adjustment direction of the previous phase-finding action, so as to more accurately locate the phase position of the motor rotor and improve the efficiency and accuracy of the phase-finding process.

[0060] It is worth noting that when the current direction of motion is opposite to the historical direction of motion, the target current electrical angle in this embodiment is half of the electrical angle adjustment value, that is, the target current electrical angle is obtained by halving the electrical angle adjustment value.

[0061] Specifically, taking the electrical angle adjustment value of the previous phase-finding action as 45 degrees and the adjustment direction as positive as an example, if the motor rotor moves in the positive direction in the current phase-finding action and the motor rotor moved in the negative direction in the previous phase-finding action, the current movement direction of the motor rotor is opposite to the historical movement direction. At this time, the electrical angle adjustment value of the previous phase-finding action needs to be halved to obtain the target current electrical angle, that is, the target current electrical angle is 22.5 degrees, and the target movement direction is reversed. Subsequently, the current electrical angle of the given current is adjusted in the opposite direction by an angle of 22.5 degrees.

[0062] Reference Figure 4 , Figure 4 This is a flowchart of the displacement compensation of the motor rotor based on the current electrical angle and initial position after phase finding, provided in the embodiments of this application. The method includes, but is not limited to, steps S401 to S403.

[0063] Step S401: Adjust the current electrical angle after phase finding by a preset angle so that the current electrical angle coincides with the preset position.

[0064] Step S402: Determine the current position of the motor rotor and adjust the given current based on the current position and the initial position.

[0065] Step S403: Perform displacement compensation on the motor rotor according to the adjusted given current.

[0066] In steps S401 to S403 of some embodiments, during the displacement compensation of the motor rotor, the embodiments of this application first adjust the current electrical angle after phase finding by a preset angle so that the current electrical angle coincides with the preset position. In this embodiment, the preset position is the q-axis in the servo system, which can be regarded as the current control mode. Then, the current position of the motor rotor is determined, and the given current is adjusted according to the current position and the initial position. By comparing the difference between the current position and the initial position, it can be determined whether the motor rotor has reached or exceeded the predetermined position, thereby achieving more precise positioning control. Then, the displacement compensation of the motor rotor is performed according to the adjusted given current, thereby realizing the adjustment of the displacement generated during the phase finding process, reducing the cumulative error, preventing the occurrence of motor runaway, and improving the positioning accuracy and reducing system oscillation caused by phase finding error.

[0067] Reference Figure 5 , Figure 5 This is a flowchart of adjusting a given current based on the current position and the initial position provided in the embodiments of this application. The method includes, but is not limited to, steps S501 to S502.

[0068] Step S501: If the current position is less than the initial position, increase the given current.

[0069] Step S502: If the current position is greater than the initial position, decrease the given current.

[0070] In steps S501 to S502 of some embodiments, during the process of adjusting the given current based on the current position and the initial position, the magnitudes of the current position and the initial position are determined. Specifically, if the current position is less than the initial position, it means that the current position of the motor rotor has not reached the initial position, and the motor rotor needs to move to a larger position value. At this time, the given current is increased by controlling the positive increment of the given current. Increasing the positive component of the current can provide the necessary torque to make the motor rotor move in the correct direction. If the current position is greater than the initial position, it means that the current position of the motor rotor has exceeded the initial position. Continuing to increase the current positively may cause the motor rotor to exceed the initial position, i.e., overshoot. At this time, the given current is decreased by controlling the negative increment of the given current. The negative increment of the current can reduce this risk. This embodiment of the application determines the direction of the increase of the given current by judging the position difference between the current position and the initial position, thereby realizing the positioning control of the motor rotor, ensuring that the motor rotor moves in a predetermined direction, preventing overshoot or runaway, and improving the stability of the servo system.

[0071] Reference Figure 6 , Figure 6 This is a flowchart of a phase-finding method provided in another embodiment of this application. The phase-finding method in this embodiment includes, but is not limited to, steps S601 to S603.

[0072] It should be noted that steps S601 to S603 occur after the motor rotor is displacement compensated according to the adjusted given current.

[0073] Step S601: Detect the compensated movement distance of the motor rotor.

[0074] Step S602: When the compensation movement distance reaches the preset distance, stop the given current and determine the compensation position after the motor rotor displacement compensation.

[0075] Step S603: When the compensation position coincides with the initial position, the displacement compensation operation ends.

[0076] In steps S601 to S603 of some embodiments, after the motor rotor is displaced according to the adjusted given current, the present application embodiment will detect the compensated movement distance of the motor rotor again, and then determine whether the compensated movement distance of the motor rotor has reached the preset distance. When the compensated movement distance reaches the preset distance, it means that the motor rotor has reached the set maximum distance. If the motor rotor continues to rotate after reaching the predetermined angle, it may cause overshoot. At this time, the given current needs to be removed, that is, the given current is stopped to prevent overshoot and avoid motor overload and damage. The present application embodiment will also determine the compensated position of the motor rotor after displacement compensation, and then judge the compensated position and the initial position to determine whether the motor rotor has reached the initial position. When the compensated position coincides with the initial position, it means that the position of the motor rotor after position compensation has reached the initial position, and there is no need to perform displacement compensation operation again. At this time, the displacement compensation operation can be directly ended to achieve accurate compensation of the displacement of the motor rotor and avoid the situation of motor rotor misalignment.

[0077] Reference Figure 7 , Figure 7 This is a flowchart of a phase-finding method provided in another embodiment of this application. The phase-finding method in this embodiment includes, but is not limited to, steps S701 to S703.

[0078] It should be noted that steps S701 to S703 occur after the compensation position of the motor rotor displacement has been determined.

[0079] Step S701: When the compensation position does not coincide with the initial position, determine the number of compensation cycles for the motor rotor.

[0080] Step S702: When the number of compensation attempts has not reached the preset threshold, adjust the given current according to the compensation position and the initial position to perform the next displacement compensation operation.

[0081] Step S703: When the number of compensation attempts reaches the preset threshold, the displacement compensation operation ends.

[0082] In steps S701 to S703 of some embodiments, after determining the compensated position of the motor rotor displacement compensation, it is determined whether the compensated position coincides with the initial position. If the compensated position does not coincide with the initial position, it indicates that the compensated position is inconsistent with the initial position. It is necessary to determine the number of compensations for the motor rotor and determine whether the number of compensations has reached a preset threshold. If the number of compensations has not reached the preset threshold, the displacement compensation operation can continue, that is, the given current is adjusted according to the compensated position and the initial position, and steps S402 to S403 are repeated to perform the next displacement compensation operation. The specific displacement compensation operation can be referred to the above steps S402 to S403, steps S501 to S502, and steps S601 to S602, which will not be repeated here in the embodiments of this application. When the number of compensations has reached the preset threshold, the displacement compensation operation is directly terminated.

[0083] It should be noted that the preset threshold in this application embodiment can be set according to the user's needs or the historical operation parameters of the servo system. Specifically, the preset threshold in this application embodiment is three times, that is, after the compensation number reaches three times, even if the compensation position does not coincide with the initial position, the displacement compensation operation will not be performed again, and the entire displacement compensation process will end directly.

[0084] Reference Figure 8 , Figure 8 This is a flowchart of a phase-finding method provided in another embodiment of this application. The phase-finding method in this embodiment includes, but is not limited to, step S801.

[0085] Step S801: When the given current amplitude reaches the preset current amplitude for the first time, and the movement distance does not reach the preset distance, stop the given current from flowing, and reverse the direction of the electrical angle of the given current.

[0086] In step S801 of some embodiments, when the given current amplitude reaches the preset current amplitude for the first time and the movement distance does not reach the preset distance, it is necessary to stop the given current and reverse the direction of the current electrical angle of the given current, thereby preventing the motor from outputting an incorrect phase finding result due to hitting a hard limit and improving the phase finding accuracy.

[0087] It is worth noting that, in this embodiment of the application, the current electrical angle is reversed after the phase-finding operation is completed to verify whether the phase-finding failure is caused by a hard limit.

[0088] To explain the above phase-finding method more clearly, a specific example will be provided below.

[0089] Example 1: Example 1 provides a detailed description of the phase-finding method, controller, servo system, and storage medium.

[0090] The phase-finding method in this example mainly includes parameter setting, phase-finding, and displacement compensation. Each step will be explained in detail below.

[0091] In the parameter setting stage, this example allows you to set the maximum single movement distance (Degmax), maximum phase-finding current (Imax), current increment step, time interval between two movements, and movement restriction direction during the phase-finding process according to the current operating conditions and performance requirements of the servo system. This will enhance the accuracy of the phase-finding results under different operating conditions and improve the adaptability of the phase-finding function.

[0092] It is worth noting that after the phase-finding parameters are set and before entering the phase-finding stage, the initial position of the motor rotor before phase-finding needs to be recorded so that the displacement generated during the phase-finding process can be compensated in the displacement compensation stage.

[0093] During the phase-finding process, the electrical angle of the given current is continuously adjusted according to the direction of the motor rotor's movement until the true position of the motor rotor is found. First, the initial phase of the given current is set to 180°. Then, the given current amplitude is gradually increased according to the current increment step set in the parameter setting section. Simultaneously, it is monitored in real time whether the motor rotor's movement distance reaches Degmax or whether the current amplitude reaches Imax. When the motor current amplitude reaches Imax, but the motor rotor's movement distance is still less than Degmax, the electrical angle of the current is considered to be the actual position of the rotor's d-axis.

[0094] In some embodiments, the present application sets parameters according to the system operating conditions in the parameter setting stage before phase finding begins, thereby enhancing the accuracy of the phase finding results and improving the adaptability of this phase finding method.

[0095] The phase-finding process will be explained in detail below.

[0096] refer to Figure 9 , Figure 9 This is a flowchart of phase finding for a motor rotor provided as an example in this application.

[0097] Step S1: Gradually increase the given current amplitude of the motor and detect the motor status.

[0098] Step S2: If the movement distance of the motor rotor reaches the maximum single movement distance Degmax, remove the given current.

[0099] Step S3: Adjust the given current electrical angle according to the direction of motor movement and the direction of movement restriction.

[0100] Step S4: If the amplitude of the given current to the motor reaches the maximum phase-finding current Imax, and the movement distance of the motor rotor is less than the maximum single movement distance Degmax, then the given current is removed.

[0101] Step S5: Determine whether this is the first time the state of step S4 has been reached.

[0102] Step S6: If so, take the reverse current electrical angle.

[0103] Step S7: If not, output the current electrical angle after phase finding.

[0104] In some embodiments, during the phase-finding process, the given current amplitude of the motor is gradually increased while the motor status is monitored. If the motor rotor travels a distance of Degmax, the given current is removed, and the electrical angle of the given current is adjusted according to the direction of the motor rotor's movement and the set limiting direction. Specifically, if the direction of movement is positive, the electrical angle is adjusted in the negative direction; if the direction of movement is negative, the electrical angle is adjusted in the positive direction. After waiting for a set interval and the motor stops moving, the given current amplitude is gradually increased again. If the given current amplitude of the motor reaches Imax and the motor travels a distance less than Degmax, the given current is removed. When this state is reached for the first time, the electrical angle of the current needs to be reversed to prevent the motor from outputting an incorrect phase-finding result due to hitting a hard limit and stalling. If the given current amplitude reaches Imax twice consecutively, it proves that the phase-finding result is correct, and the displacement compensation stage begins.

[0105] refer to Figure 10 , Figure 10 This is a flowchart of adjusting the electrical angle of the current provided in one example of this application.

[0106] Step S8: Obtain the direction of motor movement for this phase-finding action.

[0107] Step S9: Determine whether the direction of this movement is a restricted direction.

[0108] Step S10: If the direction of motion is not a restricted direction, determine whether the directions of motion in the two preceding and subsequent movements are consistent.

[0109] Step S11: If the directions of the two movements are consistent, continue to adjust the given current electrical angle according to the previous electrical angle adjustment value.

[0110] Step S12: If the directions of the two movements are opposite, adjust the electrical angle to half and then adjust the electrical angle again.

[0111] Step S13: If the direction of motion is a restricted direction, adjust the current angle directly in the opposite direction to the current motor motion.

[0112] In some embodiments, it is necessary to obtain the motor movement direction of this phase-finding action. Then, it is determined whether this movement direction is a restricted direction. If the movement direction is not a restricted direction, the current angle needs to be adjusted based on the previous and subsequent motor movement directions. If the previous and subsequent movement directions are the same, it means that the current angle relative to the motor rotor has not changed, so the given current angle is adjusted according to the previous adjustment value. If the previous and subsequent movement directions are opposite, it means that the current angle adjustment has crossed the motor rotor, causing a change in the current angle relative to the motor rotor. Therefore, the current angle needs to be halved before further adjustment. If the movement direction is a restricted direction, the halving of the current angle adjustment value is skipped, and the current angle is directly adjusted in the opposite direction to the current motor movement, thus making the next motor movement direction an unrestricted direction.

[0113] In this embodiment of the application, after setting the restricted direction, if the motor movement direction is the restricted direction in each phase-finding action, the motor movement direction will definitely be the non-restricted direction in the next phase-finding action, thereby restricting the displacement of the motor in the restricted direction during the phase-finding process, which facilitates phase-finding when there are position restrictions.

[0114] After completing the phase-finding action of the motor rotor, the displacement compensation stage in this embodiment will compensate for the motor rotor displacement generated in the phase-finding stage, and at the same time detect whether the motor movement direction is consistent with the theoretical direction during the compensation process. If they are inconsistent, it means that the phase-finding result converges to the s pole of the rotor d-axis.

[0115] refer to Figure 11 , Figure 11 This is a flowchart of displacement compensation for a motor rotor provided as an example in this application.

[0116] Step S14: Add 90° to the electrical angle of the current.

[0117] Step S15: Determine the direction of current increase based on the difference between the current position and the initial position before phase search.

[0118] Step S16: Gradually increase the given current amplitude in the direction of current increase.

[0119] Step S17: Determine whether the movement distance of the motor rotor has reached the maximum single movement distance Degmax.

[0120] Step S18: If the movement distance of the motor rotor reaches the maximum single movement distance Degmax, determine whether the current position coincides with the initial position.

[0121] Step S19: If the current position coincides with the initial position, the displacement compensation process ends.

[0122] Step S20: If the current position does not coincide with the initial position, determine whether the displacement compensation count is greater than or equal to 3 times.

[0123] It should be noted that if the number of displacement compensations is less than 3, steps S15 to S20 are repeated; if the number of displacement compensations is greater than or equal to 3, the displacement compensation process ends.

[0124] In some embodiments, after entering the displacement compensation stage, the current electrical angle is first increased by 90° so that the current electrical angle coincides with the q-axis position; this can be considered as current control mode. Then, the current increase direction is determined based on the difference between the current position and the initial position before phase finding. If the current position is greater than the initial position, the current increases negatively; if the current position is less than the initial position, the current increases positively. When the movement distance reaches Degmax, the current is removed, and the difference between the updated current position and the initial position is recalculated. If the current position coincides with the initial position, the displacement compensation stage ends; otherwise, the next current increase direction is determined based on the position difference, and displacement compensation is performed again, with a maximum of 3 compensation cycles.

[0125] It should be noted that in the displacement compensation stage, this application determines whether the actual direction of motor movement is consistent with the theoretical direction, thereby preventing the phase search result from converging to the S pole and causing the motor to run away.

[0126] Example 2: Example 2 is a comparison example of current electrical angle adjustment before and after setting the limiting direction.

[0127] refer to Figure 12 , Figure 12 This is a schematic diagram illustrating the comparison of current and electrical angle adjustments provided in an example of this application.

[0128] Before setting the direction constraint, in the nth phase-finding operation, the motor rotor's direction of motion is positive, and the angle difference between the current electrical angle and the motor rotor is less than 22.5°. The current electrical angle of the given current is adjusted 45° in the negative direction, crossing the motor rotor position. Therefore, in the (n+1)th phase-finding operation, the motor's direction of motion is negative. Since the first two directions of motion are inconsistent, the current electrical angle adjustment value is halved to 22.5°. At this time, the current electrical angle is adjusted 22.5° in the positive direction, but the relative position with the rotor remains unchanged. Therefore, in the (n+2)th phase-finding operation, the motor's direction of motion is still negative. Since the first two directions of motion are consistent, the electrical angle adjustment value remains unchanged. The current electrical angle is adjusted 22.5° in the positive direction, crossing the motor rotor. Therefore, in the (n+3)th phase-finding operation, the motor's direction of motion is positive.

[0129] With the negative direction set as the limiting direction, in the nth phase-finding operation, the motor rotor's movement direction is positive, and the current angle is smaller than the motor rotor's angle (less than 22.5°). The given current angle is adjusted 45° in the negative direction, crossing the motor rotor's position; therefore, in the (n+1)th phase-finding operation, the motor's movement direction is negative. Since the (n+1)th motor movement direction is the limiting direction, the current adjustment value is halved, remaining at 45°. Because the motor rotor's movement direction is negative and the current adjustment value remains unchanged, the current angle is adjusted to the value of the angle during the previous positive direction movement; therefore, in the (n+2)th phase-finding operation, the motor's movement direction is positive. Since the first two movements are opposite, the current angle adjustment value is halved to 22.5°. The current angle is adjusted 22.5° in the negative direction, resulting in a negative movement direction in the (n+3)th phase-finding operation. In summary, after setting the restricted direction, each time the motor moves in the restricted direction, the motor current angle will be adjusted back to the value of the previous non-restricted direction. This ensures that the motor moves in the non-restricted direction during the next phase-finding action, thereby restricting the motor's movement in the restricted direction during the phase-finding process.

[0130] like Figure 13 As shown, Figure 13 This is a schematic diagram of a controller 1000 provided in one embodiment of this application.

[0131] An embodiment of this application also provides a controller 1000, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the phase-finding method described above.

[0132] Specifically, the controller 1000 in this embodiment includes at least one processor and a memory for communicatively connecting to the at least one processor; the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the control method as described in the above embodiment.

[0133] The controller 1000 in this embodiment includes one or more processors 1001 and a memory 1002. Figure 13 The example uses a processor 1001 and a memory 1002.

[0134] Processor 1001 and memory 1002 can be connected via a bus or other means. Figure 13 Taking the example of a connection between China and Israel via a bus.

[0135] Memory 1002, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory 1002 may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory 1002 may optionally include memory 1002 remotely located relative to processor 1001, and these remote memories can be connected to controller 1000 via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0136] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network nodes. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0137] It is worth noting that this embodiment also provides a servo system, including Figure 13 The controller shown, the specific implementation method and technical effects of the servo system in this application embodiment, can be referred to the specific implementation method and technical effects of the phase-finding method in any of the above embodiments.

[0138] The device or system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0139] Furthermore, one embodiment of this application provides a computer-readable storage medium storing computer-executable instructions that are executed by a processor or controller.

[0140] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory may optionally include memory remotely located relative to the processor, and these remote memories can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0141] The non-transient software program and instructions required to implement the phase-finding method of the above embodiments are stored in memory and executed by the processor, thus executing the above embodiments.

[0142] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer-readable storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer-readable storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer-readable storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0143] The above provides a detailed description of the preferred embodiments of this application. However, this application is not limited to the above-described embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application. All such equivalent modifications or substitutions are included within the scope defined by this application.

Claims

1. A phase-finding method, characterized in that, Applied to a servo system, the method includes: A given current is supplied to the motor of the servo system, and the amplitude of the given current of the motor is increased by a preset current increment step to perform a phase-finding action, and the movement distance of the motor rotor during this phase-finding action is detected. When the movement distance reaches the preset distance, the given current is stopped, the current movement direction of the motor rotor in this phase-finding action is determined, and the target movement direction and target current electrical angle are determined according to the current movement direction and the preset limiting direction. Adjust the direction of the current electrical angle of the given current toward the target direction of movement, and configure the given current to the target current electrical angle to enter the next phase-finding action; The phase search ends when the given current amplitude reaches the preset current amplitude a preset number of times. The step of determining the target motion direction and the target current electrical angle based on the current motion direction and the preset limiting direction includes: Determine the electrical angle adjustment value and historical movement direction of the previous phase-finding action, and determine the adjustment direction of the electrical angle adjustment value; If the current direction of motion is a preset restricted direction, the target direction of motion of the current electrical angle is determined as an unrestricted direction, and the electrical angle adjustment value is determined as the target current electrical angle, wherein the unrestricted direction is opposite to the restricted direction; If the current direction of motion is an unrestricted direction, the target direction of motion and the target current electrical angle are determined based on the historical direction of motion, the current direction of motion, and the adjustment direction.

2. The phase-finding method according to claim 1, characterized in that, Before applying a given current to the motor, the process also includes: Record the initial position of the motor rotor in the servo system; After the phase search is completed, the method further includes: The motor rotor is displacement compensated based on the current angle after phase finding and the initial position.

3. The phase-finding method according to claim 1, characterized in that, Determining the target motion direction and target current electrical angle based on the historical motion direction, the current motion direction, and the adjustment direction includes: If the current direction of motion is the same as the historical direction of motion, the electrical angle adjustment value is determined as the target current electrical angle, and the target direction of motion is determined as the adjustment direction; If the current direction of motion is opposite to the historical direction of motion, the electrical angle adjustment value is reduced to obtain the target current electrical angle, and the target direction of motion is determined as the opposite direction of the adjustment direction.

4. The phase-finding method according to claim 2, characterized in that, The displacement compensation of the motor rotor based on the current electrical angle after phase finding and the initial position includes: The electrical angle of the current after phase finding is adjusted by a preset angle so that the electrical angle of the current coincides with the preset position; Determine the current position of the motor rotor, and adjust the given current based on the current position and the initial position; The motor rotor is displaced according to the adjusted given current.

5. The phase-finding method according to claim 4, characterized in that, The step of adjusting the given current based on the current position and the initial position includes: If the current position is less than the initial position, increase the given current; If the current position is greater than the initial position, decrease the given current.

6. The phase-finding method according to claim 4, characterized in that, After performing displacement compensation on the motor rotor according to the adjusted given current, the method further includes: Detect the compensated movement distance of the motor rotor; When the compensated movement distance reaches the preset distance, the given current is stopped, and the compensated position of the motor rotor displacement after compensation is determined. The displacement compensation operation ends when the compensation position coincides with the initial position.

7. The phase-finding method according to claim 6, characterized in that, After determining the compensated position of the motor rotor displacement, the method further includes: When the compensation position does not coincide with the initial position, the number of compensation cycles for the motor rotor is determined. If the number of compensation attempts does not reach a preset threshold, the given current is adjusted based on the compensation position and the initial position to perform the next displacement compensation operation. or, When the number of compensation attempts reaches a preset threshold, the displacement compensation operation ends.

8. The phase-finding method according to claim 1, characterized in that, The method further includes: When the given current amplitude reaches the preset current amplitude for the first time, and the movement distance does not reach the preset distance, the given current is stopped, and the direction of the electrical angle of the given current is reversed.

9. A controller, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the phase-finding method as described in any one of claims 1 to 8.

10. A servo system, characterized in that, Includes the controller as described in claim 9.

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