A method for compensating thrust fluctuation of a moving magnet independent winding linear motor

Abstract

A method for compensating thrust fluctuation of a dynamic magnet type independent winding linear motor relates to an independent winding permanent magnet synchronous linear motor. In order to solve the problem that the existing harmonic injection method cannot solve the problem that the back electromotive force of the winding near the end is distorted, resulting in poor dynamic performance and positioning accuracy. The present invention selects a winding whose primary is fully coupled with the secondary of the motor and does not correspond to the secondary end as a compensation winding; and passes a compensation current; the solution formula of the compensation current is: #imgabs0# where i c Indicates the compensation current flowing through the compensation winding, E sum It represents the sum of the no-load back EMF of all compensation windings, F end Indicates the motor secondary end effect force, F H Indicates the ripple thrust of the motor, F T Represents the cogging force of the motor. The beneficial effect is that the dynamic performance and positioning accuracy of the motor are greatly improved.

Description

Technical Field

[0001] The invention relates to an independent winding permanent magnet synchronous linear motor. Background Art

[0002] In an iron core permanent magnet linear synchronous motor, due to the breakage of both ends of the primary iron core, the air gap magnetic field at the end is distorted, resulting in a longitudinal end effect. In addition, similar to a rotating motor, the air gap magnetic field distribution of an iron core permanent magnet linear synchronous motor will change at the core slot, which is the so-called slot effect. Usually, this thrust fluctuation caused by the end effect and the slot effect, which causes the change in magnetic resistance of the magnetic circuit, is called positioning force or magnetic resistance force. The positioning force represents a basic performance indicator of a permanent magnet synchronous linear motor and is an inherent characteristic of the linear motor. Its size and direction are independent of the motor's operating conditions. The main components of these two thrust fluctuations of a linear motor reduce the dynamic performance and positioning accuracy of the linear motor and are the goals of the linear motor body design and drive control optimization. In order to reduce the thrust fluctuation output by the motor, the armature winding is usually used to compensate for the thrust fluctuation by introducing harmonics. This method introduces the same current harmonics into all windings, and the resulting compensating thrust compensates for the thrust fluctuation component, thereby achieving the purpose of reducing the thrust fluctuation output by the motor. However, due to the existence of the end effect, the back electromotive force of the winding near the end is distorted, and the existing harmonic injection method cannot produce an ideal compensation force. Summary of the invention

[0003] The purpose of the present invention is to solve the problem that the existing harmonic injection method cannot solve the distortion of the winding back electromotive force near the end, resulting in poor dynamic performance and positioning accuracy, and proposes a thrust fluctuation compensation method for a moving magnet independent winding linear motor.

[0004] The method for compensating thrust fluctuation of a moving magnet type independent winding linear motor described in the present invention comprises the following steps:

[0005] Step 1: Select a winding whose primary is completely coupled with the secondary of the motor and whose area does not correspond to the end of the secondary as a compensation winding;

[0006] Step 2: Passing a compensation current through the compensation winding selected in step 1;

[0007] The solution formula for the compensation current is:

[0008]

[0009] Among them, i c Indicates the compensation current flowing through the compensation winding, E sum It represents the sum of the no-load back EMF of all compensation windings, F end Indicates the motor secondary end effect force, F H Indicates the ripple thrust of the motor, F T Indicates the cogging force of the motor.

[0010] The beneficial effects of the present invention are as follows: by adopting the optimization design method of the present invention, the thrust fluctuation amplitude of the motor is reduced from 5.027N, which has never been adopted, to 0.693N; the dynamic performance and positioning accuracy of the motor are greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of compensation position selection of compensation winding for a 4-pole 3-slot long stator permanent magnet linear synchronous motor in a specific implementation mode 1; (a) indicates that the 4-pole 3-slot long stator permanent magnet linear synchronous motor is in a state of primary and secondary full coupling, and (b) indicates that the 4-pole 3-slot long stator permanent magnet linear synchronous motor is in an initial transition stage;

[0012] Figure 2 Schematic diagram of compensation position selection of compensation winding for 8-pole 7-slot long stator permanent magnet linear synchronous motor in specific implementation mode 1; (a) represents the 8-pole 7-slot long stator permanent magnet linear synchronous motor in a fully coupled state, and (b) represents the 8-pole 7-slot long stator permanent magnet linear synchronous motor in an incompletely coupled state;

[0013] Figure 3 This is a thrust fluctuation comparison diagram after compensation by the dynamic magnet type independent winding linear motor thrust fluctuation compensation method described in the first specific implementation mode; wherein the dotted line represents the thrust diagram of the motor output when there is no compensation; the dotted and solid lines represent the thrust diagram of the motor output after compensation by the dynamic magnet type independent winding linear motor thrust fluctuation compensation method described in the first specific implementation mode;

[0014] Figure 4 Schematic diagram of compensation position selection for the compensation winding of the slotless independent winding linear motor in the first specific implementation mode; wherein (a) represents the primary pole matching state, and (b) represents the primary pole mismatching state; in the figure, 1 is the secondary iron yoke; 2 is the primary iron yoke; 3 is the winding; 4 is the permanent magnet;

[0015] Figure 5 Schematic diagram of compensation position selection for the compensation winding of a linear motor with slotted independent windings in the first specific implementation mode; wherein (a) represents the initial pole matching state, and (b) represents the initial pole mismatching state;

[0016] Figure 6 This is a schematic diagram of compensation position selection for the compensation winding of a slotted multi-phase independent winding linear motor in a specific implementation mode 1; wherein (a) represents the initial pole matching state, and (b) represents the initial pole mismatching state. DETAILED DESCRIPTION

[0017] Specific implementation method 1: Combination Figures 1 to 6The present embodiment describes a method for compensating thrust fluctuation of a moving magnet type independent winding linear motor, and the method comprises the following steps:

[0018] Step 1: Select a winding whose primary is completely coupled with the secondary of the motor and whose area does not correspond to the end of the secondary as a compensation winding;

[0019] Step 2: Passing a compensation current through the compensation winding selected in step 1;

[0020] The solution formula for the compensation current is:

[0021]

[0022] Among them, i c Indicates the compensation current flowing through the compensation winding, E sum It represents the sum of the no-load back EMF of all compensation windings, F end Indicates the motor secondary end effect force, F H Indicates the ripple thrust of the motor, F T Indicates the cogging force of the motor.

[0023] In this embodiment, due to the proposed compensation winding switching strategy, E sum There is no zero crossing point, and the compensation winding can always compensate for thrust fluctuations. The comparison chart of finite element simulation results obtained using maxwell2D is as follows Figure 3 As shown, by adopting the optimization design method of the present invention, the thrust fluctuation amplitude of the motor is reduced from 5.027N which has never been adopted to 0.693N.

[0024] In a preferred embodiment, the motor described in step 1 is a moving magnet independent winding linear motor;

[0025] Each coil of the stator winding of the moving magnet type independent winding linear motor is equipped with a driving circuit, and the coils are independently controlled; current compensation is performed only on certain windings.

[0026] In a preferred embodiment, for a 4-pole 3-slot long-stator permanent magnet synchronous linear motor, 4 pole pitches correspond to 3 winding widths; the compensation winding selects a winding that is fully coupled with the secondary, that is, when the long-stator permanent magnet synchronous linear motor is in a state of primary and secondary full coupling, the compensation winding selects winding No. 4; when the long-stator permanent magnet synchronous linear motor is in an initial transition stage, the compensation winding selects winding No. 4 and winding No. 5, where the winding numbers are arranged in sequence from left to right starting from No. 1.

[0027] In this embodiment, for the moving magnet type independent winding linear motor, each coil of the stator winding is equipped with a drive circuit, and the coils can be independently controlled without affecting each other. Therefore, current compensation can be performed only on certain windings. The selection of the compensation winding follows the law of winding back-EMF distortion. For the long stator permanent magnet synchronous linear motor, the secondary and primary sizes are matched with each other during design. Taking a 4-pole 3-slot motor as an example, 4 pole pitches correspond to 3 winding widths. However, during the operation of the motor, the coils at both ends will be partially coupled to the secondary, causing changes in the back-EMF of the end coils. In addition, the end effect generated at the secondary end will also cause distortion to the back-EMF of the end winding. Therefore, the compensation winding should be selected to be fully coupled with the secondary; Figure 1 For example, for Figure 1 (a), the motor is in the state of full primary-secondary coupling, windings 3 and 5 are located in the secondary end area, the back EMF will be distorted, so the compensation winding is selected as winding 4; Figure 1 (b), the motor is in the transition stage of windings 3 and 6. Windings 3 and 6 are coupled with the secondary part and contain back-EMF harmonics, so windings 4 and 5 are selected as compensation windings.

[0028] In a preferred embodiment, when the number of pole pairs of the moving magnet independent winding linear motor is greater than 2, the compensation winding selects two adjacent coils.

[0029] In a preferred embodiment, for the 8-pole 7-slot long stator permanent magnet synchronous linear motor, windings No. 4 to No. 7 are all in a fully coupled state, and the compensation windings select windings No. 5 and No. 6. As the 8-pole 7-slot long stator permanent magnet synchronous linear motor runs, there is a zero point in the back EMF of winding No. 5, that is, when winding No. 5 passes through the back EMF zero point, it switches to winding No. 7; winding No. 6 passes through the back EMF zero point and switches to winding No. 8, where the windings are numbered from left to right starting from No. 1.

[0030] In this embodiment, for a moving magnet type independent winding linear motor with a large number of pole pairs, the compensation winding can select two adjacent coils; Figure 2 For example, the motor is in a state of full primary and secondary coupling, and windings 4 to 7 are all in a state of full coupling. At this time, windings 5 ​​and 6 can be selected as compensation windings. As the motor runs, the back electromotive force of winding 5 has a zero point. At this time, the compensation current of the winding will not be able to generate compensation thrust, so when the winding passes the zero point, the compensation winding needs to be switched, that is, when winding 5 passes the back electromotive force zero point, it is switched to winding 7; winding 6 passes the back electromotive force zero point and is switched to winding 8, and so on.

[0031] In a preferred embodiment, the motor described in step one is a slotless independent winding linear motor. When the primary and secondary are matched, winding No. 3 is selected as the compensation winding; when the primary and secondary are not matched, winding No. 3 and winding No. 4 are selected as the compensation windings; the winding numbers are arranged in sequence from left to right starting from No. 1.

[0032] In this embodiment, if Figure 4 As shown, primary-secondary matching means that the lengths of the primary yoke and the secondary yoke correspond exactly. For a two-pole linear motor, the length of the secondary yoke corresponds to three primary yoke lengths. However, as the secondary yoke moves, the number of windings coupled by the primary yoke becomes four, i.e., the primary-secondary pole is not matched.

[0033] In a preferred embodiment, the motor described in step one is a linear motor with slotted independent windings. When the primary and secondary are matched, winding No. 3 is selected as the compensation winding; when the primary and secondary are not matched, winding No. 3 and winding No. 4 are selected as the compensation windings; the windings are numbered from left to right starting from No. 1.

[0034] In this embodiment, if Figure 5 As shown, primary-secondary matching means that the lengths of the primary yoke and the secondary yoke correspond exactly. For a two-pole linear motor, the length of the secondary yoke corresponds to three primary yoke lengths. However, as the secondary yoke moves, the number of windings coupled by the primary yoke becomes four, i.e., the primary-secondary pole is not matched.

[0035] In a preferred embodiment, the motor described in step one is a slotted multi-phase independent winding linear motor. When the primary and secondary are matched, windings No. 3, No. 4 and No. 5 are selected as compensation windings; when the primary and secondary are not matched, windings No. 3, No. 4, No. 5 and No. 6 are selected as compensation windings; the windings are numbered in sequence from left to right starting from No. 1.

[0036] In this embodiment, if Figure 6 As shown, primary-secondary matching means that the lengths of the primary yoke and the secondary yoke correspond exactly. For a two-pole linear motor, the length of the secondary yoke corresponds to three primary yoke lengths. However, as the secondary yoke moves, the number of windings coupled by the primary yoke becomes four, i.e., the primary-secondary pole is not matched.

[0037] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for compensating thrust fluctuation of a moving magnet independent winding linear motor, characterized in that: The fluctuation compensation method comprises the following steps: Step 1: Select a winding whose primary is completely coupled with the secondary of the motor and whose area does not correspond to the end of the secondary as a compensation winding; Step 2: Passing a compensation current through the compensation winding selected in step 1; The solution formula for the compensation current is: Among them, i c Indicates the compensation current flowing through the compensation winding, E sum It represents the sum of the no-load back EMF of all compensation windings, F end Indicates the motor secondary end effect force, F H Indicates the ripple thrust of the motor, F T Indicates the cogging force of the motor.

2. The method for compensating thrust fluctuation of a moving magnet independent winding linear motor according to claim 1, characterized in that: The motor described in step 1 is a moving magnet independent winding linear motor; Each winding of the stator winding of the moving magnet type independent winding linear motor is equipped with a driving circuit, and the windings are independently controlled.

3. The method for compensating thrust fluctuation of a moving magnet independent winding linear motor according to claim 1, characterized in that: For the 4-pole 3-slot long stator permanent magnet synchronous linear motor, 4 pole pitches correspond to 3 winding widths; the compensation winding selects a winding that is fully coupled with the secondary, that is, when the long stator permanent magnet synchronous linear motor is in a state of primary and secondary full coupling, the compensation winding selects winding No. 4; when the long stator permanent magnet synchronous linear motor is in the initial transition stage, the compensation winding selects winding No. 4 and winding No. 5, where the winding numbers are arranged in sequence from left to right starting from No.

1.

4. The method for compensating thrust fluctuation of a moving magnet independent winding linear motor according to claim 1, characterized in that: When the number of pole pairs of the moving magnet independent winding linear motor is greater than 2, the compensation winding selects two adjacent windings.

5. The method for compensating thrust fluctuation of a moving magnet independent winding linear motor according to claim 4, characterized in that: For the 8-pole 7-slot long stator permanent magnet synchronous linear motor, windings 4 to 7 are all in a fully coupled state, and the compensation windings select windings 5 ​​and 6. As the 8-pole 7-slot long stator permanent magnet synchronous linear motor runs, there is a zero point in the back EMF of winding 5, that is, when winding 5 passes through the back EMF zero point, it switches to winding 7; winding 6 passes through the back EMF zero point and switches to winding 8, where the winding numbers are arranged from left to right starting from No.

1.

6. The method for compensating thrust fluctuation of a moving magnet independent winding linear motor according to claim 1, characterized in that: The motor described in step 1 is a slotless independent winding linear motor. When the primary and secondary are matched, winding No. 3 is selected as the compensation winding; when the primary and secondary are not matched, winding No. 3 and winding No. 4 are selected as the compensation windings; the winding numbers are arranged from left to right starting from No.

1.

7. The method for compensating thrust fluctuation of a moving magnet independent winding linear motor according to claim 1, characterized in that: The motor described in step 1 is a linear motor with slotted independent windings. When the primary and secondary are matched, winding No. 3 is selected as the compensation winding; when the primary and secondary are not matched, winding No. 3 and winding No. 4 are selected as the compensation windings; the winding numbers are arranged from left to right starting from No.

1.

8. The method for compensating thrust fluctuation of a moving magnet independent winding linear motor according to claim 1, characterized in that: The motor described in step one is a slotted multi-phase independent winding linear motor. When the primary and secondary are matched, windings No. 3, No. 4 and No. 5 are selected as compensation windings; when the primary and secondary are not matched, windings No. 3, No. 4, No. 5 and No. 6 are selected as compensation windings; the winding numbers are arranged from left to right starting from No. 1.

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