Micro-motion phase-finding method and system for linear motor system, and storage medium

Abstract

The present invention relates to the field of linear motor control technology, and discloses a linear motor system micro-phase search method and system, and a storage medium. The method comprises the following steps: S1, injecting D-axis excitation current into the motor for open-loop motion control to perform current excitation, wherein an initial given electrical angle m 0 =180°; S2, after stopping the current excitation, judge according to the change in the grating scale D: First, judge whether |D|<θ min / N or e‑f≤θ min If so, then with different given electrical angles m j Repeat the current excitation until |D|≥θ is satisfied min / N and e‑f>θ min ; If not, that is, when |D|≥θ min / N and e‑f>θ min When θ is 0, it indicates that the current excitation produces displacement, and the iterative search phase is performed until |D|<θ is satisfied. min / N or e‑f≤θ min The entire positioning process of this solution has a small current and a small movement displacement, and does not require additional sensors. It effectively avoids the problems of structural interference and collision caused by long displacement and high speed, and the judgment logic is simple.

Description

Technical Field

[0001] The present invention relates to the technical field of linear motor control, and in particular to a micro-motion phase-finding method and system, and a storage medium for a linear motor system. Background Art

[0002] Linear motor servo control system is an automatic control system that enables the output controlled quantities such as the position, orientation, and state of the linear motor to follow any changes in the input target (or given value). Generally, the linear motor is equipped with an incremental grating ruler as position feedback, and the driver drives the coil to generate current and thrust to drive the mover. It is currently widely used in motion control systems for high-precision positioning platforms, and the industries include semiconductors, processing and manufacturing, and other automation fields.

[0003] When the actual linear motor is running, the initial electrical angle of the initial power-on needs to be determined so that the driver can drive the motor to move in the correct operating mode. For example, the invention patent CN115441795A discloses a method and system for positioning the initial given electrical angle of a linear motor system, and designs a binary given electrical angle search algorithm based on the pulse counting of the incremental grating ruler, which can ensure that when the motor current is small, a small current is used to generate a thrust torque, but it is not enough to drive the mover to move the distance.

[0004] However, when an actual linear motor is looking for a given electrical angle of phase, it is necessary to avoid long displacement and high speed as much as possible: for example, the traditional binary phase-finding method, pre-positioning method and other phase-finding methods cause the motor to move from a certain position θ to θ0, and the maximum operating angle may exceed 180°. This open-loop control when looking for a given electrical angle of phase is an uncontrollable movement, and long displacement and high speed may cause structural interference, collision, etc. Therefore, a micro-motion phase-finding solution is needed to ensure that the motor can find the initial electrical angle at a very small distance to avoid the problem of structural interference and collision caused by long displacement and high speed. Summary of the invention

[0005] In order to solve the problems in the prior art, an object of the present invention is to provide a micro-motion phase-finding method and system, and a storage medium for a linear motor system.

[0006] In order to achieve the above object, the present invention provides a first aspect of a linear motor system micro-motion phase-finding method, comprising the following steps:

[0007] S1, inject D-axis excitation current into the motor for open-loop motion control to perform current excitation, where the initial given electrical angle m0=180°;

[0008] S2. After stopping the current excitation, judge according to the change in the grating ruler D:

[0009] First, determine whether |D|<θ min / N or ef≤θ min If so, then with different given electrical angles m j Repeat the current excitation until |D|≥θ is satisfied min / N and ef>θ min ;

[0010] If not, that is, when |D|≥θ min / N and ef>θ min When θ is 0, it indicates that the current excitation produces displacement, and the iterative search phase is performed until |D|<θ is satisfied. min / N or ef≤θ min , and m i is not equal to 180°, the micro-motion phase search is completed; where θ min is the minimum given electrical angle at which the torque thrust causes the motor rotor to micro-move. The value of N is determined according to the micro-motion situation in the actual application of the motor. j is the number of repeated current excitations, j=0,1,2,...,m j Not equal to m0, m i It is an iterative search for a given electrical angle for phase search, i is the number of iterations, i=0,1,2,..., [f,e] is the range of the given electrical angle, m i ϵ[f,e].

[0011] Preferably, the given electrical angles m are different j Repeat the current excitation until |D|≥θ is satisfied min / N and ef>θ min , the specific process is:

[0012] m j =m j -M is a current excitation for a given electrical angle, and the grating scale change measurement D is obtained in real time until |D|>N'*θ min Or the excitation current ≥ the maximum phase-seeking current, stop current excitation, the values ​​of N' and M are determined according to the micro-motion situation in the actual application of the motor, M>N'*θ min ;

[0013] Determine the current m j Is it greater than 0? If so, go to step S1-S2; if not, it is determined that the phase search has failed.

[0014] Preferably, the iterative search is a sequential search, a binary search, a difference search or a Fibonacci search method.

[0015] Preferably, the iterative search is a binary search, and the iterative search phase finding is specifically:

[0016] If the motor electrical angle direction is consistent with the grating ruler feedback direction, the angle movement increment D>0, or the motor electrical angle direction is opposite to the grating ruler feedback direction, the angle movement increment D<0: then set the new search interval e=m i -1, f=f; number of iterations: i=i+1; given electrical angle update: m i =(f+e) / 2, given the electrical angle m i Conducting current excitation;

[0017] If the motor electrical angle direction is consistent with the grating ruler feedback direction, the angle movement increment D is less than 0; or if the motor electrical angle direction is opposite to the grating ruler feedback direction, the angle movement increment D is greater than 0: set the new search interval f=m i +1, e=e; Number of iterations: i=i+1; Update of given electrical angle: m i =(f+e) / 2, given the electrical angle m i Current excitation.

[0018] Preferably, the verification after completing the micro-motion phase finding includes the following process:

[0019] Inject Q-axis excitation current into the motor for closed-loop motion control to perform current excitation. According to the real-time acquired grating scale change measurement D, if |D|>N'*θ min Or if the excitation current is ≥ the maximum phase-seeking current, the current excitation is stopped;

[0020] According to the real-time acquired grating ruler change measurement D, first enter the verification stage 1: if the motor electrical angle direction is consistent with the grating ruler feedback direction, the angle movement increment D>0, or the motor electrical angle direction is opposite to the grating ruler feedback direction, the angle movement increment D<0, then the movement direction is correct, and the verification stage 1 verification is successful, otherwise the direction is opposite, and the phase search fails;

[0021] Let ΔI=-ΔI, and inject negative current to the motor for Q-axis excitation closed-loop motion control to perform current excitation again. After stopping the current excitation, enter the verification stage 2: if the electrical angle direction of the motor is consistent with the feedback direction of the grating ruler, the angle movement increment D is less than 0 at this time, or the electrical angle direction of the motor is opposite to the feedback direction of the grating ruler, the angle movement increment D is greater than 0 at this time, then the movement direction is correct, the verification stage 2 verification is successful, and the overall phase-seeking process is successfully completed, otherwise the direction is opposite and the phase-seeking fails; wherein, ΔI is the current unit increment of the current excitation process.

[0022] Preferably, the specific process of the current excitation is:

[0023] Inject the motor with increasing excitation current of D axis to perform open-loop motion control, and obtain the grating scale change measurement D in real time;

[0024] Determine whether the current phase-seeking stage is phase-seeking stage 1 or phase-seeking stage 2:

[0025] When it is phase-seeking stage 1, if |D|≥θ min Or if the excitation current is ≥ the maximum phase-seeking current, the excitation current decreases to 0 and the current excitation stops, otherwise the excitation current continues to be applied;

[0026] When it is phase-seeking stage 2, |D|>N'*θ min Or the excitation current ≥ the maximum phase-seeking current, the excitation current decreases to 0 and the current excitation stops, otherwise the excitation current continues to be applied; wherein, the current excitation is performed at the initial given electrical angle m0=180° and at the given electrical angle m i The current excitation for iterative phase search is the phase search stage 1; with different given electrical angles m j Repeating the current excitation is the phase-seeking stage 2.

[0027] Preferably, the method also includes initializing parameters before step S1, initializing the given electrical angle interval f=0°, e=360°, the initial excitation given electrical angle m0=180°, i=0, j=0, and the grating scale feedback change angle D=0°; setting the maximum phase-seeking current and the phase-seeking time, calculating the current unit increment ΔI through the maximum phase-seeking current and the phase-seeking time, and the initial phase-seeking stage=1.

[0028] A second aspect of the present invention provides a micro-motion phase-finding system for a linear motor system, comprising:

[0029] The current excitation open-loop control module is used to inject D-axis excitation current into the motor for open-loop motion control to perform current excitation, wherein the initial given electrical angle m0=180°;

[0030] The phase-finding module is used to determine the change in the grating scale D after stopping the current excitation:

[0031] First, determine whether |D|<θ min / N or ef≤θ min If so, then with different given electrical angles m j Repeat the current excitation until |D|≥θ is satisfied min / N and ef>θ min ;

[0032] If not, that is, when |D|≥θ min / N and ef>θ min When θ is 0, it indicates that the current excitation produces displacement, and the iterative search phase is performed until |D|<θ is satisfied. min / N or ef≤θ min , and m iis not equal to 180°, the micro-motion phase search is completed; where θ min is the minimum given electrical angle at which the torque thrust causes the motor rotor to micro-move. The value of N is determined according to the micro-motion situation in the actual application of the motor. j is the number of repeated current excitations, j=0,1,2,...,m j Not equal to m0, m i It is an iterative search for a given electrical angle for phase search, i is the number of iterations, i=0,1,2,..., [f,e] is the range of the given electrical angle, m i ϵ[f,e].

[0033] A third aspect of the present invention provides a machine-readable storage medium having instructions stored thereon, the instructions being used to enable a machine to execute the micro-motion phase-finding method of the linear motor system described above in the present application.

[0034] A fourth aspect of the present invention provides a processor for running a program, wherein the program, when run, is used to execute the steps of a micro-motion phase-finding method for a linear motor system.

[0035] Through the above technical scheme, a given electrical angle micro-motion search algorithm based on the incremental grating scale pulse counting is designed, which can ensure that when the motor moves a very small distance, after the grating scale pulse appears to judge the torque direction, the initial electrical angle can be found by a search method including but not limited to binary search, and special processing is done for the initial electrical angle of 0° or 180°. Finally, the given electrical angle verification is performed to determine whether the initial electrical angle found is correct; the entire positioning process has a small current and a small motion displacement, and no additional sensors are required, which effectively avoids the problems of structural interference and collision caused by long displacement and high speed; and the judgment logic is simple, the algorithm can be embedded in the servo drive, and can be widely used in linear motor control systems.

[0036] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0038] Figure 1 is a micro-motion phase-finding flow chart of a linear motor system according to an embodiment of the present invention;

[0039] Figure 2 This is a flow chart of verification after completing micro-motion phase finding in an embodiment of the present invention;

[0040] Figure 3is a schematic diagram of current vector injection according to an embodiment of the present invention;

[0041] Figure 4 It is a schematic diagram of open-loop motion control for injecting excitation current into a motor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0043] In fact, for a given electrical angle θ' at a certain position, the preset given electrical angle is θ0, and the counterclockwise direction is defined as the positive direction of the grating ruler movement, and the clockwise direction is defined as the negative direction of the grating ruler movement; when θ'>θ0, the torque thrust causes the mover to slightly move in the clockwise direction, corresponding to the negative direction of the grating ruler movement, and when θ'<θ0, the torque thrust direction is counterclockwise, corresponding to the positive direction of the grating ruler movement. When θ'=θ0, it indicates that the D-axis torque at this time basically coincides with the current given electrical angle, and the given electrical angle can be determined without movement. Due to factors such as motor load and friction, there is a blind spot θ in the torque thrust. min If the angle is not enough to make the actuator move slightly, the judgment range of the given electrical angle is θ0-θ min ≤θ'≤θ0+θ min .

[0044] Based on the above analysis, a first aspect of an embodiment of the present invention provides a micro-motion phase-finding method of a linear motor system to find an actual given electrical angle, comprising the following steps:

[0045] S1, inject D-axis excitation current into the motor for open-loop motion control to perform current excitation, where the initial given electrical angle m0=180°;

[0046] S2. After stopping the current excitation, judge according to the change in the grating ruler D:

[0047] First, determine whether |D|<θ min / N or ef≤θ min If yes, it means that the initial given electrical angle coincides with the current angle, and there is basically no displacement when using m0=180° excitation. j Repeat the current excitation until |D|≥θ is satisfied min / N and ef>θ min ;

[0048] If not, that is, when |D|≥θ min / N and ef>θ min When θ is 0, it indicates that the current excitation produces displacement, and the iterative search phase is performed until |D|<θ is satisfied. min / N or ef≤θ min , and m i is not equal to 180°, the micro-motion phase search is completed; where θ min is the minimum given electrical angle at which the torque thrust causes the motor rotor to micro-move. The value of N is determined according to the micro-motion situation in the actual application of the motor. j is the number of repeated current excitations, j=0,1,2,...,m j Not equal to m0, m i It is an iterative search for a given electrical angle for phase search, i is the number of iterations, i=0,1,2,..., [f,e] is the range of the given electrical angle, m i ϵ[f, e]. If the excitation current reaches the maximum phase-seeking current, but the displacement |D| is less than θ min / N, it means that only a small displacement is generated under the current electrical angle excitation, and the electrical angle can be preliminarily judged to be basically accurate; the N value should not be set too small, the smaller the electrical angle error, but it should not be set too large. In theory, the larger the N value, the more accurate the electrical angle. However, during the current excitation process, the motor will have a force release effect after the current increases from 0, and a certain amount of displacement will be generated. For example, N can be 2, 5, 8, 10, 15 or 20, etc.

[0049] Further, in step S2, at different given electrical angles m j Repeat the current excitation until |D|≥θ is satisfied min / N and ef>θ min , the specific process is:

[0050] First, the initial given electrical angle m i When current excitation is performed with m0=180°, or the condition |D|<θmin / N or ef≤θmin is satisfied, it indicates that the 180° electrical angle excitation has basically no displacement and cannot be pulled. At this time, the actual electrical angle may be 0° or 180°. In order to avoid this situation, m0 is used again. j =m j -M is a current excitation for a given electrical angle, the purpose of which is to pull the electrical angle away from 180° or 0°. j =m j -M is a current excitation for a given electrical angle, and the grating scale change measurement D is obtained in real time until |D|>N'*θ min Or the excitation current ≥ the maximum phase-seeking current, stop current excitation, the values ​​of N' and M are determined according to the micro-motion situation in the actual application of the motor, M>N'*θ min ; The value of M is determined according to the actual application, and can be 10°, 20°, 30°, or 50°, etc.;

[0051] Determine the current m jIs it greater than 0? If so, go to step S1-S2; if not, it is determined that the phase search has failed.

[0052] Furthermore, in step S2, the iterative search may be a sequential search, a binary search, a difference search or a Fibonacci search method, preferably a binary search. Taking the binary search as an example, the iterative search for phase finding is specifically as follows:

[0053] If the motor electrical angle direction is consistent with the grating ruler feedback direction, the angle movement increment D>0, or the motor electrical angle direction is opposite to the grating ruler feedback direction, the angle movement increment D<0: then set the new search interval e=m i -1, f=f; number of iterations: i=i+1; given electrical angle update: m i =(f+e) / 2, given the electrical angle m i Conducting current excitation;

[0054] If the motor electrical angle direction is consistent with the grating ruler feedback direction, the angle movement increment D is less than 0; or if the motor electrical angle direction is opposite to the grating ruler feedback direction, the angle movement increment D is greater than 0: set the new search interval f=m i +1, e=e; Number of iterations: i=i+1; Update of given electrical angle: m i =(f+e) / 2, given the electrical angle m i Current excitation.

[0055] In another embodiment of the present invention, the above embodiment performs verification after completing the micro-motion phase search to verify whether the given electrical angle found in the phase search stage is valid. Figure 1 After the micro-motion phase-finding process shown in the figure is completed, the corresponding relationship between the motor handover and the grating ruler feedback value can be obtained according to the current grating ruler feedback value and the actual initial electrical angle after micro-motion phase-finding. The subsequent process is as follows Figure 2 As shown, the following process is included:

[0056] Inject Q-axis excitation current into the motor for closed-loop motion control to perform current excitation. According to the real-time acquired grating scale change measurement D, if |D|>N'*θ min Or if the excitation current is ≥ the maximum phase-seeking current, the current excitation is stopped;

[0057] According to the real-time acquired grating ruler change measurement D, first enter the verification stage 1: if the motor electrical angle direction is consistent with the grating ruler feedback direction, the angle movement increment D>0, or the motor electrical angle direction is opposite to the grating ruler feedback direction, the angle movement increment D<0, then the movement direction is correct, and the verification stage 1 verification is successful, otherwise the direction is opposite, and the phase search fails;

[0058] Let ΔI=-ΔI, and inject negative current to the motor for Q-axis excitation closed-loop motion control to perform current excitation again. After stopping the current excitation, enter the verification stage 2: if the electrical angle direction of the motor is consistent with the feedback direction of the grating ruler, the angle movement increment D is less than 0 at this time, or the electrical angle direction of the motor is opposite to the feedback direction of the grating ruler, the angle movement increment D is greater than 0 at this time, then the movement direction is correct, the verification stage 2 verification is successful, and the overall phase-seeking process is successfully completed, otherwise the direction is opposite and the phase-seeking fails; wherein, ΔI is the current unit increment of the current excitation process.

[0059] In the embodiment of the present invention, the specific process of current excitation is:

[0060] Inject the motor with increasing excitation current of D axis to perform open-loop motion control, and obtain the grating scale change measurement D in real time;

[0061] Determine whether the current phase-seeking stage is phase-seeking stage 1 or phase-seeking stage 2:

[0062] When it is phase-seeking stage 1, if |D|≥θ min Or if the excitation current is ≥ the maximum phase-seeking current, the excitation current decreases to 0 and the current excitation stops, otherwise the excitation current continues to be applied;

[0063] When it is phase-seeking stage 2, |D|>N'*θ min Or the excitation current ≥ the maximum phase-seeking current, the excitation current decreases to 0 and the current excitation stops, otherwise the excitation current continues to be applied; wherein, the current excitation is performed at the initial given electrical angle m0=180° and at the given electrical angle m i The current excitation for iterative phase search is the phase search stage 1; with different given electrical angles m j Repeating the current excitation is the phase-seeking stage 2.

[0064] In another embodiment of the present invention, the parameters are initialized before step S1 of the above embodiment, the given electrical angle interval f=0°, e=360°, the initial excitation given electrical angle m0=180°, i=0, j=0, and the grating scale feedback change angle D=0°; the maximum phase-seeking current and the phase-seeking time are set, and the current unit increment ΔI is calculated through the maximum phase-seeking current and the phase-seeking time, and the initial phase-seeking stage = 1.

[0065] For example, Figure 1 Shown and Figure 2 As shown, a micro-motion phase-finding method for a linear motor system includes the following steps:

[0066] 1) Initialize the given electrical angle interval f=0°, e=360°, the initial given electrical angle m0=180°, the number of iterations i=0, the grating ruler feedback change angle D=0°; i=0, j=0, that is, m j=0=180° is used to handle a special case when the initial electrical angle is 0° or 180°; the current unit increment ΔI is calculated by setting the phase-seeking current and phase-seeking time; the initial phase-seeking stage = 1, the initial verification stage = 1.

[0067] 2) According to Figure 3 The current vector injection diagram shown in Figure 4 The vector current injection timing diagram shown in the figure injects D-axis current into the motor for open-loop motion control with an initial given electrical angle m0=180°. The excitation current increases by ΔI. The position changes, causing the grating ruler to generate pulse changes. If the moving distance is greater than θ min Or if the excitation current reaches the maximum phase-seeking current, the current excitation is stopped and subsequent judgment begins.

[0068] 3) In Figure 4 Before the current is injected, the grating ruler position P(T0) and the position P(T1) where the current is maximum are recorded, and the grating ruler change is calculated = P(T1)-P(T0), and the pulse change is converted into degrees D.

[0069] 4) Judge based on the change in the grating scale D:

[0070] If |D|<θ min / 10 or ef<=θ min : It means that the initial positioning given electrical angle coincides with the current angle; if m=180° at this time, it means that there is basically no displacement when using m=180° excitation, and the specific given electrical angle cannot be determined when the initial electrical angle is 0° or 180°. j Represents a given electrical angle, pull the initial electrical angle away from 0° or 180° and then find the given electrical angle again: m j =m j -30, m=m j , enter the phase-finding stage = 2; in the phase-finding stage 2, the current excitation pulls the given electrical angle to 10*θ min Then re-search the phase and go to step 2). If m j The corresponding given electrical angle cannot be pulled until m j =0, indicating that the motor has a stall problem and the phase search fails; if m is not equal to 180° at this time, it means that the given electrical angle has been found, and the verification phase begins, and go to step 7);

[0071] Otherwise if |D|≥θ min / 10 and ef>θ min : It shows that a certain displacement D is generated under the initial given electrical angle m0=180° excitation;

[0072] If (the feedback direction of the motor and the grating ruler is opposite, MotorFdbDir=0 and D>0) or (the feedback direction of the motor and the grating ruler is opposite, MotorFdbDir=1 and D<0): it indicates forward operation (the motor running direction is consistent with the current direction), go to step 5);

[0073] If (the feedback direction of the motor and the grating ruler are opposite, MotorFdbDir=0 and D<0) or (the feedback direction of the motor and the grating ruler are opposite, MotorFdbDir=1 and D>0): it indicates reverse operation (when the electrical angle direction of the motor is consistent with the feedback direction of the grating ruler, the angle movement increment D>0, or when the electrical angle direction of the motor is opposite to the feedback direction of the grating ruler, the angle movement increment D<0), go to step 6).

[0074] 5) Set a new search interval e=m-1, f=f; number of iterations: i=i+1; given electrical angle update: m=(f+e) / 2; go to step 2).

[0075] 6) Set a new search interval f=m+1, e=e; Number of iterations: i=i+1; Given electrical angle update: m=(f+e) / 2; Go to step 2). Step 1) - Step 6) Figure 1 shown.

[0076] After the phase search is completed, the verification phase begins. Figure 2 Steps shown:

[0077] 7) Calculate the actual initial given electrical angle through the current grating scale feedback value and the current given electrical angle m excitation.

[0078] 8) Inject D-axis current into the motor for closed-loop motion control. The excitation current increases by ΔI. The position changes, causing the grating ruler to produce pulse changes. If the moving distance is greater than 10*θ min Or if the excitation current reaches the maximum phase-seeking current, the current excitation is stopped and subsequent judgment begins.

[0079] 9) Before injection, record the grating ruler position P(T0) and the position of maximum current P(T1), calculate the grating ruler change = P(T1)-P(T0), and convert the pulse change into degrees D.

[0080] 10) Determine based on the change in the grating scale D:

[0081] If it is verification phase 1, the current is forward:

[0082] If (the feedback direction of the motor and the grating ruler is opposite, MotorFdbDir=0 and D>0) or (the feedback direction of the motor and the grating ruler is opposite, MotorFdbDir=1 and D<0): it indicates forward operation, ΔI=-ΔI, verification stage=2, go to step 8); otherwise, the movement direction is opposite, and the phase search fails and ends;

[0083] If it is verification phase 2, the current is reversed:

[0084] If (the feedback direction of the motor and the grating ruler is opposite, MotorFdbDir=0 and D<0) or (the feedback direction of the motor and the grating ruler is opposite, MotorFdbDir=1 and D>0): it means reverse operation, the direction is correct, the verification is successful, and the phase search is successful; otherwise, the movement direction is opposite, the phase search fails and ends.

[0085] The above method is used to perform actual micro-motion phase-finding. The practical operation process is as follows: Example

[0086] There is a motor angle θ0=60°, and the positioning blind area θ min = 1. A binary search strategy can be designed with an initial given electrical angle interval of [f, e] = [0, 360°]:

[0087] First, the initial given electrical angle is set to 180°, and the current is increased and the current is open-loop controlled. Since θ0<180°, the torque generated will cause the motor to move slightly in the positive direction. According to the increase in the number of grating scale pulses, it can be judged that θ0 is between [0, 180°]. min is 1°, and the actual electrical angle is 61°;

[0088] Set the given electrical angle to (0+180°) / 2=90°, and use the current increasing and current open-loop control mode. Since θ0<90°, the torque generated will cause the motor to move slightly in the positive direction. According to the increase in the number of grating ruler pulses, it can be judged that θ0 is between [0, 90°]. Since the motion threshold is 1°, the actual electrical angle is 62° at this time.

[0089] Set the given electrical angle to (0+90°) / 2=45°, and use the current increasing and current open-loop control mode. Since θ0>45°, the torque generated will cause the motor to slightly move in the negative direction. According to the decrease in the number of grating scale pulses, it can be judged that θ0 is between [45°, 90°]. Since the motion threshold is 1°, the actual electrical angle is 61° at this time.

[0090] Set the given electrical angle to (90°+45°) / 2=67.5°≈67°, and use the current increasing and current open-loop control mode. Since θ0<67°, the torque generated will cause the motor to slightly move in the positive direction. According to the increase in the number of grating ruler pulses, it can be judged that θ0 is between [45°, 67°]. Since the motion threshold is 1°, the actual electrical angle is 62° at this time.

[0091] Set the given electrical angle to (67°+45°) / 2=56°, and use the current increasing and current open-loop control mode. Since θ0>56°, the torque generated will cause the motor to slightly move in the negative direction. According to the decrease in the number of grating scale pulses, it can be judged that θ0 is between [56°, 67°]. Since the motion threshold is 1°, the actual electrical angle is 61° at this time.

[0092] Set the given electrical angle to (67°+56°) / 2=61.5°≈61°, and use the current increasing and current open loop control mode. Since the given electrical angle error is only 0.5° at this time, the torque generated may sometimes be insufficient to drive the motor to move slightly, that is, |D|<θ min / 10; (or when the binary search interval size is smaller than the positioning blind area or the required accuracy of a given electrical angle, such as (ef)<=θ min ),

[0093] Record the current grating ruler position P0. Based on the P0 corresponding to the current actual electrical angle of 61°, the given electrical angle corresponding to the number of grating ruler pulses at each position can be calculated later.

[0094] The electrical angle is verified by the control method of current increment and current closed loop. Since the electrical angle is accurate, the electrical angle will be positively biased when a positive current is applied. If the motor current direction is opposite to the feedback, D>0, otherwise D<0; the electrical angle will be reversely biased when a negative current is applied. If the motor current direction is opposite to the feedback, D<0, otherwise D>0;

[0095] Verification is successful and phase search is completed. Example

[0096] There is a motor angle θ0 = 0° or 180°, and the positioning blind area θ min = 1. A binary search strategy can be designed with an initial given electrical angle interval of [f, e] = [0, 360°]:

[0097] First, the initial given electrical angle is set to 180°, and the current is increased and the current is open-loop controlled. Since θ0=0° or 180°, the torque generated is sometimes not enough to drive the motor to move slightly, that is, |D|<θ min / 10; enter phase-seeking stage 2, m j =m j -30=150°, m=mj ;

[0098] Entering the phase-finding stage 2, use m=150° for excitation. Since the motion threshold is θ min *10, the motor angle θ0 will be pulled to 170° or 10°. After the excitation is completed, it will re-enter the phase-finding stage 1, m=180° and repeat the phase-finding as in Example 1.

[0099] Based on the same inventive concept, a second aspect of an embodiment of the present invention provides a micro-motion phase-finding system for a linear motor system, comprising:

[0100] The current excitation open-loop control module is used to inject D-axis excitation current into the motor for open-loop motion control to perform current excitation, wherein the initial given electrical angle m0=180°;

[0101] The phase-finding module is used to determine the change in the grating scale D after stopping the current excitation:

[0102] First, determine whether |D|<θ min / N or ef≤θ min If so, then with different given electrical angles m j Repeat the current excitation until |D|≥θ is satisfied min / N and ef>θ min ;

[0103] If not, that is, when |D|≥θ min / N and ef>θ min When θ is 0, it indicates that the current excitation produces displacement, and the iterative search phase is performed until |D|<θ is satisfied. min / N or ef≤θ min , and m i is not equal to 180°, the micro-motion phase search is completed; where θ min is the minimum given electrical angle at which the torque thrust causes the motor rotor to micro-move. The value of N is determined according to the micro-motion situation in the actual application of the motor. j is the number of repeated current excitations, j=0,1,2,...,m j Not equal to m0, m i It is an iterative search for a given electrical angle for phase search, i is the number of iterations, i=0,1,2,..., [f,e] is the range of the given electrical angle, m i ϵ[f,e].

[0104] A third aspect of an embodiment of the present invention provides a machine-readable storage medium having instructions stored thereon, the instructions being used to enable a machine to execute the micro-motion phase-finding method of the linear motor system described above in the present application.

[0105] A fourth aspect of an embodiment of the present invention provides a processor for running a program, wherein the program, when being run, is used to execute: the micro-motion phase-finding method of the linear motor system as described above.

[0106] To sum up, the technical solution of the present invention designs a given electrical angle micro-motion search algorithm based on the incremental grating scale pulse counting, which can ensure that when the motor moves a very small distance, after the grating scale appears a pulse to judge the torque direction, the initial electrical angle can be found by a search method including but not limited to binary search, and special processing is done for the initial electrical angle of 0° or 180°. Finally, the given electrical angle verification is performed to determine whether the initial given electrical angle found is correct; the entire positioning process has a small current and a small motion displacement, and no additional sensors are required, which effectively avoids the problems of structural interference and collision caused by long displacement and high speed; and the judgment logic is simple, the algorithm can be embedded in a servo drive, and can be widely used in linear motor control systems.

[0107] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity, or apparatus.

[0108] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A micro-motion phase-finding method for a linear motor system, characterized in that: The following steps are involved: S1, inject D-axis excitation current into the motor for open-loop motion control to perform current excitation, where the initial given electrical angle m0=180°; S2. After stopping the current excitation, judge according to the change in the grating ruler D: First, determine whether |D|<θ min / N or ef≤θ min If so, then with different given electrical angles m j Repeat the current excitation until |D|≥θ is satisfied min / N and ef>θ min ; If not, that is, when |D|≥θ min / N and ef>θ min When θ is 0, it indicates that the current excitation produces displacement, and the iterative search phase is performed until |D|<θ is satisfied. min / N or ef≤θ min , and m i is not equal to 180°, the micro-motion phase search is completed; where, θ min is the minimum given electrical angle at which the torque thrust causes the motor rotor to micro-move. The value of N is determined according to the micro-motion situation in the actual application of the motor. j is the number of repeated current excitations, j=0,1,2,...,m j Not equal to m0, m i It is an iterative search for a given electrical angle for phase search, i is the number of iterations, i=0,1,2,..., [f,e] is the range of the given electrical angle, m i ϵ[f, e]; set a new search interval during the iteration: e=m i -1, f=f or f=m i +1, e=e; Number of iterations: i=i+1.

2. The method according to claim 1, characterized in that The given electrical angle m j Repeat the current excitation until |D|≥θ is satisfied min / N and ef>θ min , the specific process is: m j =m j -M is a current excitation for a given electrical angle, and the grating scale change measurement D is obtained in real time until |D|>N'*θ min Or the excitation current ≥ the maximum phase-seeking current, stop current excitation, the values ​​of N' and M are determined according to the micro-motion situation in the actual application of the motor, M>N'*θ min ; Determine the current m j Is it greater than 0? If so, go to step S1-S2; if not, it is determined that the phase search has failed.

3. The method according to claim 2, characterized in that The iterative search is a sequential search, a binary search, a difference search or a Fibonacci search method.

4. The method according to claim 3, characterized in that The iterative search is a binary search, and the iterative search phase finding is specifically: If the motor electrical angle direction is consistent with the grating ruler feedback direction, the angle movement increment D>0, or the motor electrical angle direction is opposite to the grating ruler feedback direction, the angle movement increment D<0: then set the new search interval e=m i -1, f=f; number of iterations: i=i+1; given electrical angle update: m i =(f+e) / 2, given the electrical angle m i Conducting current excitation; If the motor electrical angle direction is consistent with the grating ruler feedback direction, the angle movement increment D is less than 0; or if the motor electrical angle direction is opposite to the grating ruler feedback direction, the angle movement increment D is greater than 0: set the new search interval f=m i +1, e=e; number of iterations: i=i+1; given electrical angle update: m i =(f+e) / 2, given the electrical angle m i Current excitation.

5. The method according to claim 2, characterized in that: After completing the micro-motion phase search, verification is performed, including the following process: Inject Q-axis excitation current into the motor for closed-loop motion control to perform current excitation. According to the real-time acquired grating scale change measurement D, if |D|>N'*θ min Or if the excitation current is ≥ the maximum phase-seeking current, the current excitation is stopped; According to the real-time acquired grating ruler change measurement D, first enter the verification stage 1: if the motor electrical angle direction is consistent with the grating ruler feedback direction, the angle movement increment D>0, or the motor electrical angle direction is opposite to the grating ruler feedback direction, the angle movement increment D<0, then the movement direction is correct, and the verification stage 1 verification is successful, otherwise the direction is opposite, and the phase search fails; Let ΔI=-ΔI, and inject negative current to the motor for Q-axis excitation closed-loop motion control to perform current excitation again. After stopping the current excitation, enter the verification stage 2: if the electrical angle direction of the motor is consistent with the feedback direction of the grating ruler, the angle movement increment D is less than 0 at this time, or the electrical angle direction of the motor is opposite to the feedback direction of the grating ruler, the angle movement increment D is greater than 0 at this time, then the movement direction is correct, the verification stage 2 verification is successful, and the overall phase-seeking process is successfully completed, otherwise the direction is opposite and the phase-seeking fails; wherein, ΔI is the current unit increment of the current excitation process.

6. The method according to any one of claims 1 to 4, characterized in that: The specific process of current excitation is as follows: Inject the motor with increasing excitation current of D axis to perform open-loop motion control, and obtain the grating scale change measurement D in real time; Determine whether the current phase-seeking stage is phase-seeking stage 1 or phase-seeking stage 2: When it is phase-seeking stage 1, if |D|≥θ min Or if the excitation current is ≥ the maximum phase-seeking current, the excitation current decreases to 0 and the current excitation stops, otherwise the excitation current continues to be applied; When it is phase-seeking stage 2, |D|>N'*θ min Or the excitation current ≥ the maximum phase-seeking current, the excitation current decreases to 0 and the current excitation stops, otherwise the excitation current continues to be applied; wherein, the current excitation is performed at the initial given electrical angle m0=180° and at the given electrical angle m i The current excitation for iterative phase search is the phase search stage 1; with different given electrical angles m j Repeating the current excitation is the phase-seeking stage 2.

7. The method according to claim 6, characterized in that The method also includes initializing parameters before step S1, initializing a given electrical angle interval f=0°, e=360°, an initial excitation given electrical angle m0=180°, i=0, j=0, and a grating scale feedback change angle D=0°; setting a maximum phase-seeking current and a phase-seeking time, calculating a current unit increment ΔI through the maximum phase-seeking current and the phase-seeking time, and an initial phase-seeking stage=1.

8. A micro-motion phase-finding system for a linear motor system, characterized in that: include: The current excitation open-loop control module is used to inject D-axis excitation current into the motor for open-loop motion control to perform current excitation, wherein the initial given electrical angle m0=180°; The phase-finding module is used to determine the change in the grating scale D after stopping the current excitation: First, determine whether |D|<θ min / N or ef≤θ min If so, then with different given electrical angles m j Repeat the current excitation until |D|≥θ is satisfied min / N and ef>θ min ; If not, that is, when |D|≥θ min / N and ef>θ min When θ is 0, it indicates that the current excitation produces displacement, and the iterative search phase is performed until |D|<θ is satisfied. min / N or ef≤θ min , and m i is not equal to 180°, the micro-motion phase search is completed; where, θ min is the minimum given electrical angle at which the torque thrust causes the motor rotor to micro-move. The value of N is determined according to the micro-motion situation in the actual application of the motor. j is the number of repeated current excitations, j=0,1,2,...,m j Not equal to m0, m i It is an iterative search for a given electrical angle for phase search, i is the number of iterations, i=0,1,2,..., [f,e] is the range of the given electrical angle, m i ϵ[f, e]; set a new search interval during the iteration: e=m i -1, f=f or f=m i +1, e=e; Number of iterations: i=i+1.

9. A machine-readable storage medium having instructions stored thereon, wherein the instructions are used to enable a machine to execute the method of any one of claims 1 to 7 of the present application.

10. A processor, characterized in that: Used to run a program, wherein the program, when run, is used to execute: the micro-motion phase-finding method for a linear motor system as described in any one of claims 1-7.

Images