A method for zero position identification of a three-phase alternating current permanent magnet synchronous linear motor under spring load

Abstract

The application relates to a method for identifying zero position of a three-phase alternating current permanent magnet synchronous linear motor under spring load, which comprises the following steps: moving a motor mover to an initial position of a magnetic pole according to a pole pitch, reading a grating ruler reading of 0 as an initial zero position angle of the motor mover, obtaining a motor mover position reading by the grating ruler, obtaining balance formulas of fe1, fe2 and fe3 respectively according to a force balance formula; obtaining theta by a trigonometric function cos(A-B) operation; calculating the initial zero position angle of the motor mover; and obtaining the initial zero position angle of the motor mover through the grating ruler reading corresponding to the initial position of the motor rotor and the theta c after obtaining the theta. The application mainly indirectly calculates the initial zero position angle of the motor rotor according to motor rotor position information fed back by the grating ruler, through a force balance formula and an angle operation formula.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of permanent magnet synchronous linear motor, in particular to a method for identifying zero position of three-phase alternating current permanent magnet synchronous linear motor under spring load. BACKGROUND

[0002] At present, the permanent magnet synchronous linear motor mainly comprises a shell, a linear track arranged in the shell and a motor mover arranged on the linear track, a spring is arranged between the motor mover and the shell, a stator magnetic block is arranged on one side adjacent to the motor mover, and a grating ruler is arranged on the other side adjacent to the motor mover, a reading head device for reading the reading of the grating ruler is arranged on the motor mover, and the reading head and the grating ruler are used for measuring the mover electric angle of the motor mover. Figure 1 As shown in the description, the permanent magnet synchronous linear motor generates a magnetic field through the stator magnetic block (schematic diagram F), and the winding of the motor mover (schematic diagram C) is supplied with alternating current, and the energized winding generates a force in the magnetic field generated by the stator magnetic block, thereby pushing the motor mover to move up and down.

[0003] As shown in the description, Figure 1 The place where the energized coil (the motor current flows from outside to inside, such as the direction of the figure) and the magnetic pole N are completely perpendicular is the zero position of the motor; for the permanent magnet synchronous linear motor, the initial position of the motor zero position is an important factor in control, and the accuracy of the initial position of the motor directly affects the motion performance of the motor. In the prior art, the automatic identification method of the motor zero position is to output a force of a corresponding size to a specified position, and then the motor mover of the permanent magnet synchronous motor is turned to the specified position, which is the initial zero position of the motor. However, in actual application, the motor mover will carry a certain load when moving. According to the foregoing manner, the motor rotor does not run to the specified position. Once the zero position of the linear motor mover is identified incorrectly or a certain error occurs, the permanent magnet synchronous linear motor will appear reverse motion or out of step when starting, which will cause the failure of starting, and further affect the vector control of the permanent magnet synchronous linear motor. Therefore, it is urgent to design a zero phase initial method to solve the problem. SUMMARY

[0004] The present application provides a method for identifying the zero position of a three-phase alternating current permanent magnet synchronous linear motor under spring load, to solve the problem that the zero position of the traditional linear motor mover is identified incorrectly during operation and cannot accurately run to the zero position.

[0005] To solve the above technical problems, the present application provides a method for identifying the zero position of a three-phase alternating current permanent magnet synchronous linear motor under spring load, which comprises the following steps:

[0006] Step one, run the motor mover to the initial position of the magnetic pole according to the pole pitch, read the grating ruler reading as 0, and set the initial zero position angle of the motor mover as Θc;

[0007] Step two, given an electromagnetic force fe1, after the motor runs stably, assume that the motor reaches position 1, read the grating ruler reading as x1, and set the position distance zero angle as θ;

[0008] Step three, given an electromagnetic force fe2 (fe2> fe1), after the motor runs stably, assume that the motor reaches position 2, read the grating ruler reading as x2, the motor moves θ1 angle more than under the electromagnetic force fe1, θ1 angle = Θc (x1-x2);

[0009] Step four, given an electromagnetic force fe3 (fe3> fe2), after the motor runs stably, assume that the motor reaches position 3, read the grating ruler reading as x3, the motor moves θ2 angle more than under the electromagnetic force fe1, θ2 = Θc (x3-x1);

[0010] Step five, when the motor is at rest, the grating ruler obtains the motor position reading, and the balance formulas of fe1, fe2 and fe3 are obtained according to the force balance formula;

[0011] Step six, θ is obtained by the operation of the trigonometric function cos (A-B);

[0012] Step seven, the initial zero angle of the motor is calculated; after θ is obtained, the initial zero angle of the motor is obtained according to the grating ruler reading corresponding to the initial position of the motor rotor.

[0013] As a further improvement of the application, in step five, when the motor runs stably and is at rest, the whole system is in a force balance state, and the following balance formulas of fe1, fe2 and fe3 can be obtained:

[0014] fe1*cos(θ)+G=f*x1 (1)

[0015] fe2*cos(θ-θ1)+G=f*x2 (2)

[0016] fe3*cos(θ-θ2)+G=f*x3 (3)

[0017] In the formula, f is the spring elastic coefficient, θ is the to-be-identified quantity, θ1, θ2, fe1, fe2, fe3, x1, x2 and x3 are obtained in the above steps and are known quantities.

[0018] As a further improvement of the application, in step five, by (2)-(1), (3)-(1), G is eliminated, and the following formula can be obtained:

[0019] fe2*cos(θ-θ1)-fe1*cos(θ)=f(x2-x1) (4)

[0020] fe3*cos(θ-θ2)-fe1*cos(θ)=f(x3-x1) (5)

[0021] As a further improvement of the present application, in step six, assuming x2-x1=a1, x3-x1=a2; eliminating variable f can obtain: a2(fe2*cos(θ-θ1)-fe1*cos(θ))-a1(fe3*cos(θ-θ2)-fe1*cos(θ))=0 (6)

[0022] In formula (6), the only variable is θ, and according to the principle of trigonometric function, the following can be obtained:

[0023] cos(A-B)=cos(A)cos(B)-sin(A)sin(B) (7)

[0024] Substituting formula (7) into formula (6), the relationship between sin(θ) and cos(θ) can be obtained, and then θ can be calculated according to the trigonometric function relationship sin2(θ)+cos2(θ)=1 (8).

[0025] As a further improvement of the present application, in step five, the spring force f is equal to the gravity G when the motor rotor is at rest.

[0026] The present application also provides a three-phase alternating current permanent magnet synchronous linear motor zero position identification system under spring load, comprising a storage unit and a processor, the storage unit stores instructions for the processor to process to realize the steps of the above-mentioned three-phase alternating current permanent magnet synchronous linear motor zero position identification method under spring load.

[0027] The present application has the beneficial effect that the present application mainly calculates the initial zero position angle of the motor rotor indirectly through the force balance formula and the angle operation formula according to the motor rotor position information fed back by the grating ruler. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The embodiment structure diagram of the alternating current permanent magnet synchronous linear motor is shown. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the related drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0030] It should be noted that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements can also be present. Where an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements can also be present.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application.

[0032] The concept of pole pitch is the distance between the same name magnetic poles in a phase of linear motor, that is, the distance between adjacent two magnetic poles in the same phase, mm unit. The pole pitch of linear motor is equivalent to the distance of rotor of rotary motor for one round, because linear motor is a pair of magnetic poles, two-pole motor. That is, the motor runs through a pole pitch in a pulse frequency period, which is equivalent to one round of rotary motor. The rotor of motor changes a period relative to the ground for each pair of magnetic poles, that is 360 degrees, and the electric angle is related to the pole pitch of motor rotor running.

[0033] The existing permanent magnet synchronous linear motor for zero phase recognition, as shown in Figure 1 The motor zero position is the place where the energized coil (the motor current flows from outside to inside, such as the direction of the figure) and the magnetic pole N are completely perpendicular. The existing automatic recognition method of zero position of permanent magnet synchronous linear motor: when ignoring the spring force fx and gravity G, a fixed electric angle is usually given, and a force fe of appropriate size is given to make the motor runner move to the place where the magnetic pole N is perpendicular, and the position of the motor at this time is the initial zero position of the motor. That is, when ignoring the spring force fx and gravity G, a fixed electric angle is usually given, and a force fe of appropriate size is given to make the motor runner move to the place where the magnetic pole N is perpendicular, and the position of the motor at this time is the initial zero position of the motor.

[0034] However, in actual application, the motor runner is pulled by a spring, and the resultant force of the spring tension and gravity (i.e. fx+G) is an upward force. In this case, a fixed force fe is given, and the linear motor runner is difficult to ensure that the linear motor runner runs to the zero position (initial position) under the influence of the resultant force (fx+G). Once the zero position recognition of the linear motor runner is wrong or has a certain error, it will cause the linear motor runner to move in the opposite direction or out of step when the permanent magnet synchronous linear motor starts, resulting in failure to start, and also affect the vector control of the permanent magnet synchronous linear motor. Therefore, it is urgent to design a zero phase initial method to solve the problem.

[0035] As shown in Figure 1As shown, in order to solve the technical problems in the prior art, the embodiment of the present application provides a method for identifying zero position of three-phase alternating current permanent magnet synchronous linear motor under spring load, and the identification method comprises the following steps:

[0036] Step one, according to the pole pitch, the motor mover is run to the initial position of the magnetic pole, the reading of the grating ruler is 0, the initial zero position angle of the motor mover is set as Θc;

[0037] Step two, a given electromagnetic force fe1 is given, after the motor mover is stably run, it is assumed that the motor mover reaches position 1, the reading of the grating ruler is x1, and the position distance from the zero position angle is θ;

[0038] Step three, a given electromagnetic force fe2 (fe2> fe1) is given, after the motor mover is stably run, it is assumed that the motor mover reaches position 2, the reading of the grating ruler is x2, the motor mover moves θ1 angle more than under the electromagnetic force fe1, θ1 angle = Θc (x1-x2);

[0039] Step four, a given electromagnetic force fe3 (fe3> fe2) is given, after the motor mover is stably run, it is assumed that the motor mover reaches position 3, the reading of the grating ruler is x3, the motor mover moves θ2 angle more than under the electromagnetic force fe1, θ2 = Θc (x3-x1);

[0040] Step five, when the motor mover is at rest, the grating ruler obtains the motor mover position reading, and the balance formulas of fe1, fe2 and fe3 are obtained according to the force balance formula; when the motor mover is stably run and at rest, the whole system is in a force balance state, and the following balance formulas of fe1, fe2 and fe3 can be obtained:

[0041] fe1*cos(θ)+G=f*x1 (1)

[0042] fe2*cos(θ-θ1)+G=f*x2 (2)

[0043] fe3*cos(θ-θ2)+G=f*x3 (3)

[0044] In the formula, f is a spring elastic coefficient, θ is a to-be-identified quantity, θ1, θ2, fe1, fe2, fe3, x1, x2 and x3 are obtained in the above steps and are known quantities.

[0045] From (2)-(1) and (3)-(1), G can be eliminated, and the following formula can be obtained:

[0046] fe2*cos(θ-θ1)-fe1*cos(θ)=f(x2-x1) (4)

[0047] fe3*cos(θ-θ2)-fe1*cos(θ)=f(x3-x1) (5)

[0048] Step six, by the operation of the trigonometric function cos(A-B) to obtain θ;

[0049] In step six, assuming x2-x1=a1, x3-x1=a2; eliminating the variable f can be obtained: a2(fe2*cos(θ-θ1)-fe1*cos(θ))-a1(fe3*cos(θ-θ2)-fe1*cos(θ))=0 (6)

[0051] In formula (6), the only variable is θ, and according to the principle of trigonometric function, the following can be obtained:

[0052] cos(A-B)=cos(A)cos(B)-sin(A)sin(B) (7)

[0053] By substituting formula (7) into formula (6), the relationship between sin(θ) and cos(θ) can be obtained, and then θ can be calculated according to the trigonometric function relationship sin2(θ)+cos2(θ)=1 (8).

[0054] Step seven, calculating the initial zero position angle of the motor mover; after obtaining θ, the initial zero position angle of the motor mover is obtained according to the grating ruler reading corresponding to the initial position of the motor rotor.

[0055] From the above process, it can be seen that the present application mainly calculates the initial zero position angle of the motor rotor according to the motor rotor position information fed back by the grating ruler, through the force balance formula and the angle operation formula. The initial identification problem of the zero phase of the three-phase alternating current permanent magnet synchronous linear motor under the spring load can be solved, the present application has strong applicability, is suitable for both with load and without load, and meets the actual working condition, and is technically realizable.

[0056] As a further improvement of the present application, in step five, when the motor mover is at rest, the spring force f is equal to the gravity G.

[0057] The present application also provides a spring load three-phase alternating current permanent magnet synchronous linear motor zero position identification system, which comprises a storage unit and a processor, and the storage unit stores instructions for the processor to process to realize the steps of the spring load three-phase alternating current permanent magnet synchronous linear motor zero position identification method.

[0058] To solve the above technical problems, the application provides a zero position identification system of a three-phase alternating current permanent magnet synchronous linear motor under spring load, which comprises a storage unit and a processor, and the storage unit stores instructions for the processor to process to realize the steps of the zero position identification method of the three-phase alternating current permanent magnet synchronous linear motor under spring load.

[0059] The technical features of the above embodiments can be combined in any manner, and to make the description concise, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the description.

[0060] The above embodiments only express the preferred embodiments of the application, the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the application, a number of modifications and improvements can be made, which belong to the protection scope of the application. Therefore, the protection scope of the patent of the application should be subject to the appended claims.

Claims

1. A method for zero-position identification of a three-phase AC permanent magnet synchronous linear motor under spring load, characterized in that: Its identification method includes the following steps: Step 1: Move the motor mover to the initial position of the magnetic pole according to the pole pitch, and read the grating ruler reading as 0. The initial zero position angle of the motor mover is set as Θc. Step 2: Given an electromagnetic force fe1, after the motor mover stabilizes, assume the motor mover reaches position 1 and reads the grating ruler reading as x1. Let the angle between this position and the zero position be θ. Step 3: Given an electromagnetic force fe2 (fe2>fe1), after the motor mover stabilizes, assume the motor mover reaches position 2 and the reading on the grating ruler is x2. The motor mover moves an additional angle θ1 compared to the electromagnetic force fe1. Angle θ1=Θc(x1-x2). Step 4: Given an electromagnetic force fe3 (fe3 > fe2), after the motor mover stabilizes, assume the motor mover reaches position 3 and reads the grating ruler reading as x3. The motor mover moves an additional angle θ2 compared to the electromagnetic force fe1, θ2 = Θc(x3 - x1). Step 5: When the motor mover is stationary, the grating ruler obtains the position reading of the motor mover, and obtains the balance formulas for fe1, fe2, and fe3 respectively according to the force balance formula. Step 6: Obtain θ using the trigonometric function cos(AB); Step 7: Calculate the initial zero-position angle of the motor mover; after obtaining θ, use the grating ruler reading corresponding to the initial position of the motor rotor to determine the initial zero-position angle of the motor mover through Θc. In step five, when the motor rotor is running stably and at rest, the entire system is in a state of force equilibrium, and the following equilibrium formulas for fe1, fe2, and fe3 can be obtained: fe1*cos(θ)+G=f*x1 (1) fe2*cos(θ-θ1)+G=f*x2 (2) fe3*cos(θ-θ2)+G=f*x3 (3) In the formula: f is the spring constant, θ is the quantity to be identified, and θ1, θ2, fe1, fe2, fe3, x1, x2, and x3 are all obtained in the above steps and are known quantities; In step five, by eliminating G from (2)-(1) and (3)-(1), we can obtain: fe2*cos(θ-θ1)-fe1*cos(θ)=f(x2-x1) (4) fe3*cos(θ-θ2)-fe1*cos(θ)=f(x3-x1)(5); In step six, assume x2-x1 = a1, x3-x1 = a2; eliminating variable f yields: a2(fe2*cos(θ-θ1)-fe1*cos(θ))-a1(fe3*cos(θ-θ2)-fe1*cos(θ))=0 (6) In equation (6), the only variable is θ. According to the principle of trigonometric functions, we can obtain: cos(AB)=cos(A)cos(B)-sin(A)sin(B))(7) Equation (7) can be inserted into equation (6) to obtain the relationship between sin(θ) and cos(θ). Then, θ can be calculated from the trigonometric function relationship sin2(θ)+cos2(θ)=1(8).

2. The method for zero-position identification of a three-phase AC permanent magnet synchronous linear motor under spring load according to claim 1, characterized in that: In step five, when the motor rotor is stationary, the spring force f is equal to the gravity G.

3. A zero-position identification system for a three-phase AC permanent magnet synchronous linear motor under spring load, characterized in that, It includes a storage unit and a processor, wherein the storage unit stores instructions for the processor to process in order to implement the steps of the zero-position identification method for a three-phase AC permanent magnet synchronous linear motor under spring load as described in any one of claims 1-2.

Images