Design method of permanent magnet linear motor and permanent magnet linear motor

Abstract

This invention discloses a design method and a permanent magnet linear motor, relating to the field of motors. According to a preset motor unit selection strategy, N motor sub-units are selected, satisfying preset pole and slot selection conditions and arranged sequentially. The total number of stator slots in the N motor sub-units is equal to the total number of permanent magnets to ensure the same pole and slot characteristics of the motor. Based on a combined cogging force and a preset size correction strategy, the first dimension of the initial rectangular teeth of the first motor sub-unit and the second dimension of the final rectangular teeth of the last motor sub-unit are corrected to ensure that the combined edge force and combined cogging force meet preset cancellation conditions within the allowable design error range. This achieves phase superposition and amplitude cancellation between the combined cogging force and the combined edge force, effectively weakening the positioning force. This results in a low-positioning-force, same-pole, same-slot permanent magnet linear motor, which is more conducive to practical production applications.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and more specifically, to a design method for a permanent magnet linear motor and the permanent magnet linear motor itself. Background Technology

[0002] Permanent magnet linear motors, as key components in high-precision machining and manufacturing, are widely used in various scenarios such as rail transportation and precision testing. These motors often employ a slotted structure; however, in this structure, the motor's permeability typically exhibits periodic fluctuations between the slotted and unslotted areas. This results in thrust fluctuations in the permanent magnet linear motor. More specifically, these thrust fluctuations are primarily caused by positioning forces, which are composed of the superposition of cogging forces and edge forces. Current technologies mainly aim to reduce these two forces separately to decrease the positioning force, such as by using skewed poles or slots. However, this approach weakens the motor's thrust while reducing the positioning force. Therefore, designing an effective solution to reduce the positioning force is a pressing issue that needs to be addressed. Summary of the Invention

[0003] The problem solved by this invention is to provide a design method and a permanent magnet linear motor. By canceling the amplitude of the phase superposition between the combined cogging force and the combined edge force, the positioning force is effectively weakened, resulting in a permanent magnet linear motor with low positioning force and the same pole and slot, which is more conducive to practical production applications.

[0004] To address the above problems, this invention provides a design method for a permanent magnet linear motor, comprising:

[0005] N motor sub-units are selected according to a preset motor unit selection strategy, which meet the preset pole slot selection conditions and are arranged sequentially. N is an integer greater than 1. The preset pole slot selection condition is that the total number of stator slots included in the N motor sub-units is equal to the total number of permanent magnets included.

[0006] Determine the combined cogging force corresponding to N motor subunits;

[0007] The first dimension of the initial rectangular tooth of the first motor subunit and the second dimension of the last rectangular tooth of the last motor subunit are corrected according to the combined cogging force and the preset dimension correction strategy, so that the combined edge force obtained by superimposing the first edge force corresponding to the corrected initial rectangular tooth and the second edge force corresponding to the corrected last rectangular tooth and the combined cogging force satisfy the preset cancellation condition within the allowable design error range. The preset cancellation condition is that the amplitude of the combined cogging force and the combined edge force are equal and the phase is opposite.

[0008] The beneficial effects of this invention are as follows: by canceling the amplitude of the phase superposition between the combined cogging force and the combined edge force, the positioning force is effectively weakened, resulting in a low positioning force permanent magnet linear motor with the same pole and same slot, which is more conducive to practical production applications.

[0009] Furthermore, based on a preset motor unit selection strategy, N motor sub-units that meet preset pole slot selection conditions and are arranged sequentially are selected, including:

[0010] S21: Select the pole-slot ratio and size of the first motor subunit to obtain the first motor subunit that meets the preset size design requirements; the first motor subunit includes a permanent magnet corresponding to the target number of poles with the pole-slot ratio, and also includes an initial rectangular tooth, a middle rectangular tooth, an end rectangular tooth, and a stator slot located between the teeth and corresponding to the target number of slots with the pole-slot ratio.

[0011] S22: Determine the amplitude and phase of the first cogging force corresponding to the first motor subunit;

[0012] S23: Determine the pole slot ratio and size of the remaining motor sub-units according to the preset pole slot selection conditions, the first amplitude, and the first phase;

[0013] S24: Determine the amplitude and phase of the second cogging force corresponding to each of the remaining motor sub-units;

[0014] S25: The first tooth cogging force and the second tooth cogging force are superimposed to obtain the undetermined combined tooth cogging force;

[0015] S26: Determine whether the amplitude of the undetermined combined cogging force is less than the preset combined force amplitude. If not, return to S23 to select a new remaining motor subunit; if yes, proceed to the step of determining the combined cogging force corresponding to N motor subunits.

[0016] In this scheme, this setting can effectively ensure that the amplitude of the undetermined combined cogging force corresponding to the selected N motor sub-units is less than the preset resultant force amplitude, thus meeting the design requirements.

[0017] Furthermore, the first dimension of the initial rectangular teeth of the first motor subunit and the second dimension of the final rectangular teeth of the last motor subunit are corrected according to the synthesized cogging force and the preset size correction strategy, including:

[0018] S31: Select the first dimension of the initial rectangular teeth of the first motor subunit and the second dimension of the final rectangular teeth of the last motor subunit according to the preset size design requirements.

[0019] S32: The first end force corresponding to the corrected initial rectangular tooth is superimposed with the second end force of the corrected final rectangular tooth to determine the undetermined composite end force;

[0020] S33: The undetermined composite edge force is superimposed with the composite tooth groove force to obtain the undetermined positioning force;

[0021] S34: Determine whether the amplitude of the positioning force to be determined is less than the amplitude of the preset positioning force; if yes, end the loop; if no, return to S31 to select a new first dimension and a second dimension.

[0022] In this scheme, the size of the initial rectangular teeth and the final rectangular teeth on both sides of the permanent magnet linear motor can be effectively selected through this setting, so as to effectively reduce the positioning force.

[0023] Furthermore, after determining the combined cogging force corresponding to the N motor sub-units, the following also includes:

[0024] The third dimension of the auxiliary rectangular tooth is selected based on the combined cogging force and is located between at least one set of adjacent motor sub-units, so that the combined end force after the first end force, the second end force and the third end force corresponding to the auxiliary rectangular tooth are superimposed and the combined cogging force satisfies the preset cancellation condition within the allowable range of design error.

[0025] This solution further suggests that auxiliary rectangular teeth can be set together with the corrected initial rectangular teeth and the final rectangular teeth to adjust the combined edge force, so as to ensure that the undetermined positioning force meets the design requirements.

[0026] The present invention also provides a permanent magnet linear motor, which is obtained according to the steps of the design method of permanent magnet linear motor as described above. The permanent magnet linear motor includes a mover and N motor sub-units arranged in sequence, where N is an integer greater than 1.

[0027] Each motor subunit includes multiple permanent magnets disposed on the mover, and also includes an initial rectangular tooth, an intermediate rectangular tooth, an end rectangular tooth arranged in sequence, and multiple stator slots located between the rectangular teeth within the motor subunit.

[0028] Furthermore, at least one set of adjacent motor sub-units is provided with auxiliary rectangular teeth.

[0029] In this solution, by setting auxiliary rectangular teeth, the combined end force is specifically obtained by superimposing the first end force, the second end force, and the third end force corresponding to the auxiliary rectangular teeth, which can better adjust the combined end force of the permanent magnet linear motor.

[0030] Furthermore, the first length of the auxiliary rectangular tooth along the x-axis is less than the second length, where the second length is the distance along the x-axis between the ending rectangular tooth of the preceding motor subunit and the initial rectangular tooth of the following motor subunit.

[0031] Furthermore, the second length is an odd multiple of the pole pitch corresponding to the permanent magnet.

[0032] In this scheme, this setting ensures that the magnetomotive force star diagram of the entire permanent magnet linear motor is symmetrical. Attached Figure Description

[0033] Figure 1 A flowchart illustrating a design method for a permanent magnet linear motor provided by this invention;

[0034] Figure 2 A schematic diagram of the structure of a permanent magnet linear motor comprising a first motor subunit with 7 poles and 6 slots and a second motor subunit with 5 poles and 6 slots, for a total of 12 poles and 12 slots, provided by the present invention.

[0035] Explanation of reference numerals in the attached figures:

[0036] In the first motor subunit: 11-initial rectangular tooth, 12-first intermediate rectangular tooth, 13-second intermediate rectangular tooth, 14-third intermediate rectangular tooth, 15-fourth intermediate rectangular tooth, 16-fifth intermediate rectangular tooth, 17-final rectangular tooth, 41-permanent magnet; In the second motor subunit: 21-initial rectangular tooth, 22-first intermediate rectangular tooth, 23-second intermediate rectangular tooth, 24-third intermediate rectangular tooth, 25-fourth intermediate rectangular tooth, 26-fifth intermediate rectangular tooth, 27-final rectangular tooth, 42-permanent magnet; 5-auxiliary rectangular tooth, τ3-second length, W3-first length of auxiliary rectangular tooth along the x-axis, τ-pole pitch, W1-first dimension, W2-second dimension. Detailed Implementation

[0037] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0038] Please refer to Figure 1 , Figure 1 A flowchart illustrating a design method for a permanent magnet linear motor provided by this invention.

[0039] The design method of this permanent magnet linear motor includes:

[0040] S11: Select N motor sub-units that meet the preset pole slot selection conditions and are arranged sequentially according to the preset motor unit selection strategy. N is an integer greater than 1. The preset pole slot selection condition is that the total number of stator slots included in the N motor sub-units is equal to the total number of permanent magnets included.

[0041] S12: Determine the combined cogging force corresponding to N motor sub-units;

[0042] S13: Correct the first dimension of the initial rectangular tooth of the first motor subunit and the second dimension of the last rectangular tooth of the last motor subunit according to the combined cogging force and the preset dimension correction strategy, so that the combined edge force and the combined cogging force obtained by superimposing the first edge force corresponding to the corrected initial rectangular tooth and the second edge force corresponding to the corrected last rectangular tooth meet the preset cancellation condition within the allowable range of design error. The preset cancellation condition is that the amplitude of the combined cogging force and the combined edge force are equal and the phase is opposite.

[0043] Specifically, there is no particular limitation on the number N of the motor sub-units; multiple units can be set within the allowable range of the design length to meet the low positioning force requirements of the entire permanent magnet linear motor. It is understood that after step S13, various design parameters for assembling the permanent magnet linear motor can be output, including pole-slot ratios and dimensional information.

[0044] It should also be noted that the allowable range of design error takes into account the effects of various factors such as actual processing losses. It is only necessary to ensure that the amplitudes of the combined tooth groove force and the combined edge force are as close as possible and that their phases are as different as 180 degrees to achieve phase reversal. Therefore, the combined tooth groove force and the combined edge force meet the preset cancellation conditions within the allowable range of design error.

[0045] As can be seen, this application achieves the same pole and same slot of the motor by setting the total number of stator slots to be equal to the total number of permanent magnets, and by satisfying the preset cancellation condition by canceling the phase superposition amplitude between the combined cogging force and the combined edge force, a lower positioning force can be obtained. This effectively weakens the positioning force and results in a low positioning force permanent magnet linear motor with the same pole and same slot, which is more conducive to practical production applications.

[0046] As a preferred embodiment, N motor sub-units that meet preset pole slot selection conditions and are arranged sequentially are selected according to a preset motor unit selection strategy, including:

[0047] S21: Select the pole-slot ratio and size of the first motor subunit to obtain the first motor subunit that meets the preset size design requirements; the first motor subunit includes a permanent magnet corresponding to the target number of poles with the pole-slot ratio, as well as an initial rectangular tooth, a middle rectangular tooth, an end rectangular tooth, and a stator slot located between the teeth and corresponding to the target number of slots with the pole-slot ratio.

[0048] S22: Determine the amplitude and phase of the first cogging force corresponding to the first motor subunit;

[0049] S23: Determine the pole slot ratio and dimensions of the remaining motor sub-units based on the preset pole slot selection conditions, the first amplitude, and the first phase;

[0050] S24: Determine the amplitude and phase of the second cogging force corresponding to each remaining motor subunit;

[0051] S25: The first tooth cogging force and the second tooth cogging force are superimposed to obtain the undetermined combined tooth cogging force;

[0052] S26: Determine whether the amplitude of the unknown combined cogging force is less than the preset combined force amplitude. If not, return to S23 to select a new remaining motor subunit; if yes, proceed to the step of determining the combined cogging force corresponding to N motor subunits.

[0053] In this embodiment, the preset size design requirements take into account basic design information such as size constraints. Based on this, the pole-slot ratio and size of the first motor sub-unit are first selected, such as... Figure 1 As shown, if the first motor subunit with 7 poles and 6 slots is selected, then the target number of poles is 7, which includes 7 permanent magnets, and the target number of slots is 6, which includes 6 stator slots. Specifically, S22 can be calculated based on the cogging force generated by a single stator slot and the phase difference between each stator slot, combined with the amplitude of the cogging force generated by each stator slot, to obtain the amplitude and phase of the first cogging force corresponding to the first motor subunit.

[0054] The preset pole and slot selection condition is that the total number of stator slots in the N motor sub-units is equal to the total number of permanent magnets. Accordingly, in S23, taking the first motor sub-unit as having 7 poles and 6 slots as an example, a second motor sub-unit with (3k-1) poles and (3k) slots can be selected to form a permanent magnet linear motor with the same pole and slot, where k is an integer not less than 2. Therefore, the following can be selected: Figure 1 The second motor subunit with 5 poles and 6 slots is selected as the remaining motor subunit, and the amplitude and phase of the second cogging force corresponding to the second motor subunit are then determined. The phases of the cogging forces generated by each motor subunit are different, and their superposition can reduce the amplitude, resulting in the undetermined composite cogging force.

[0055] Determine whether the amplitude of the unknown combined cogging force is less than the preset combined force amplitude. If yes, it means that the selection is correct and proceed to the step of determining the combined cogging force corresponding to N motor sub-units. If no, it means that further adjustment is needed and return to S23. Specifically, assuming that the second motor sub-unit with 5 poles and 6 slots cannot meet the design requirements, after returning to S23, you can select the second motor sub-unit with 8 poles and 9 slots, 11 poles and 12 slots, etc.

[0056] It should also be noted that the remaining motor sub-units here are multiple motor sub-units when N is an integer not less than 3; the specific value of the preset resultant force amplitude can be flexibly determined according to actual needs; the distance between the ending rectangular teeth of the previous motor sub-unit and the initial rectangular teeth of the next motor sub-unit must be an odd multiple of the pole pitch, specifically including but not limited to 3 times.

[0057] As a preferred embodiment, correcting the first dimension W1 of the initial rectangular teeth of the first motor subunit and the second dimension W2 of the final rectangular teeth of the last motor subunit according to the combined cogging force and a preset size correction strategy includes:

[0058] S31: Select the first dimension W1 of the initial rectangular teeth of the first motor subunit and the second dimension W2 of the final rectangular teeth of the last motor subunit according to the preset size design requirements.

[0059] S32: The first end force corresponding to the corrected initial rectangular tooth is superimposed with the second end force of the corrected final rectangular tooth to determine the undetermined composite end force;

[0060] S33: The unknown composite edge force and the composite tooth groove force are superimposed to obtain the unknown positioning force;

[0061] S34: Determine whether the amplitude of the positioning force to be determined is less than the amplitude of the preset positioning force; if yes, end the loop; if no, return to S31 to select a new first size W1 and a second size W2.

[0062] In this embodiment, in order to ensure the design requirements of the composite edge force, the first dimension W1 and the second dimension W2 need to be corrected, as described above, and will not be repeated here. It should also be noted that the phase of the finally determined positioning force to be determined is different from the phase of the preset positioning force, with a difference of nearly 180 degrees, and the amplitudes of the two are close to satisfy the principle of opposite phases and canceling amplitudes. The specific value of the preset positioning force amplitude can be set according to actual needs.

[0063] As a preferred embodiment, after determining the combined cogging force corresponding to the N motor subunits, the method further includes:

[0064] The third dimension of the auxiliary rectangular tooth is selected based on the first resultant force amplitude and the first resultant force phase, and is set between at least one set of adjacent motor sub-units, so that the combined end force and the combined tooth cogging force after the first end force, the second end force and the third end force corresponding to the auxiliary rectangular tooth are superimposed, satisfy the preset cancellation condition within the allowable range of design error.

[0065] In this embodiment, auxiliary rectangular teeth can also be set between at least one set of adjacent motor sub-units, and the third end force corresponding to the auxiliary rectangular teeth participates in the superposition and synthesis of the combined end force.

[0066] Please refer to Figure 2 , Figure 2 This is a schematic diagram of the structure of a permanent magnet linear motor provided by the present invention.

[0067] The permanent magnet linear motor is obtained according to the steps of the design method of permanent magnet linear motor as described above. The permanent magnet linear motor includes a mover and N motor sub-units arranged in sequence, where N is an integer greater than 1.

[0068] Each motor subunit includes multiple permanent magnets mounted on the mover, as well as initial rectangular teeth, intermediate rectangular teeth, and final rectangular teeth arranged in sequence, and multiple stator slots located between the rectangular teeth within the motor subunit.

[0069] In this embodiment, the description of the permanent magnet linear motor provided in this invention is provided in the embodiment of the design method for the permanent magnet linear motor described above, and will not be repeated here. It should also be noted that the N motor sub-units can be arranged sequentially along the x-axis. The initial rectangular teeth, intermediate rectangular teeth, and final rectangular teeth in any motor sub-unit are arranged sequentially along the x-axis, and the permanent magnet is mounted on the mover, positioned below the aforementioned teeth along the z-axis; please refer to... Figure 2 , Figure 2 Taking N=2, i.e., two motor sub-units, as an example: The first motor sub-unit can be a 7-pole, 6-slot unit, including an initial rectangular tooth 11, a first intermediate rectangular tooth 12, a second intermediate rectangular tooth 13, a third intermediate rectangular tooth 14, a fourth intermediate rectangular tooth 15, a fifth intermediate rectangular tooth 16, and an ending rectangular tooth 17. These teeth form 6 stator slots (stator slots are used to place the motor windings). Figure 2The diagram directly shows the phase connection method of the windings in each stator slot, including phases A, X, Z, C, B, and Y; permanent magnet 41 (there are 7 permanent magnets below the 6 stator slots in the first motor subunit; to avoid confusion, only the leftmost permanent magnet is shown in the attached diagram); the second motor subunit can be a 5-pole 6-slot unit, including initial rectangular tooth 21, first middle rectangular tooth 22, second middle rectangular tooth 23, third middle rectangular tooth 24, fourth middle rectangular tooth 25, fifth middle rectangular tooth 26, and ending rectangular tooth 27, forming 6 stator slots (these slots are also used to place the windings). Figure 2 The diagram provides a specific arrangement for winding phases, and permanent magnet 42 (there are 5 permanent magnets below the 6 stator slots in the second motor subunit; to avoid confusion in wiring, only the rightmost permanent magnet is shown in the attached diagram).

[0070] In a preferred embodiment, at least one set of adjacent motor subunits is provided with auxiliary rectangular teeth 5.

[0071] In this scheme, to further ensure that the combined end force of the permanent magnet linear motor meets the design requirements, an auxiliary rectangular tooth 5 can be set. The combined end force is then obtained by superimposing the first end force, the second end force, and the third end force corresponding to the auxiliary rectangular tooth 5. Please refer to... Figure 2 An auxiliary rectangular tooth 5 is provided in the gap between the ending rectangular tooth 17 in the first motor subunit and the initial rectangular tooth 21 in the second motor subunit. The combined end force is specifically obtained by superimposing the first end force, the second end force and the third end force.

[0072] In a preferred embodiment, the first length of the auxiliary rectangular tooth 5 along the x-axis is less than the second length τ3, where the second length τ3 is the distance along the x-axis between the ending rectangular tooth of the preceding motor subunit and the initial rectangular tooth of the following motor subunit.

[0073] In this plan, please refer to Figure 2 The first length of the auxiliary rectangular tooth 5 along the x-axis is W3, and the second length τ3 is the length between the ending rectangular tooth 17 of the first motor subunit and the initial rectangular tooth 21 of the second motor subunit.

[0074] In a preferred embodiment, the second length τ3 is an odd multiple of the pole pitch τ corresponding to the permanent magnet.

[0075] In this scheme, this setting ensures the symmetry of the magnetomotive force star diagram of the entire permanent magnet linear motor. It should be noted that the pole pitch τ corresponding to the permanent magnets here is as follows: Figure 2 As shown; this odd multiple includes, but is not limited to, 3 times.

[0076] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

[0077] It should also be noted that in this specification, relational terms such as first, second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not imply any such actual relationship or order between these entities or operations.

Claims

1. A design method for a permanent magnet linear motor, characterized in that, include: N motor sub-units are selected according to a preset motor unit selection strategy, which meet the preset pole slot selection conditions and are arranged sequentially. N is an integer greater than 1. The preset pole slot selection condition is that the total number of stator slots included in the N motor sub-units is equal to the total number of permanent magnets included. Determine the combined cogging force corresponding to N motor subunits; The first dimension of the initial rectangular tooth of the first motor subunit and the second dimension of the last rectangular tooth of the last motor subunit are corrected according to the combined cogging force and the preset size correction strategy, so that the combined edge force obtained by superimposing the first edge force corresponding to the corrected initial rectangular tooth and the second edge force corresponding to the corrected last rectangular tooth and the combined cogging force satisfy the preset cancellation condition within the allowable design error range. The preset cancellation condition is that the amplitude of the combined cogging force and the combined edge force are equal and the phase is opposite. Specifically, the first dimension of the initial rectangular tooth of the first motor subunit and the second dimension of the final rectangular tooth of the last motor subunit are corrected according to the combined cogging force and the preset size correction strategy, as follows: S31: Select the first dimension of the initial rectangular teeth of the first motor subunit and the second dimension of the final rectangular teeth of the last motor subunit according to the preset size design requirements. S32: The first end force corresponding to the corrected initial rectangular tooth is superimposed with the second end force of the corrected final rectangular tooth to determine the undetermined composite end force; S33: The undetermined composite edge force is superimposed with the composite tooth groove force to obtain the undetermined positioning force; S34: Determine whether the amplitude of the positioning force to be determined is less than the amplitude of the preset positioning force; if yes, end the loop; if no, return to S31 to select a new first dimension and a second dimension.

2. The design method of the permanent magnet linear motor as described in claim 1, characterized in that, N motor sub-units that meet the preset pole slot selection conditions and are arranged sequentially are selected according to the preset motor unit selection strategy, including: S21: Select the pole-slot ratio and size of the first motor subunit to obtain the first motor subunit that meets the preset size design requirements; the first motor subunit includes a permanent magnet corresponding to the target number of poles with the pole-slot ratio, and also includes an initial rectangular tooth, a middle rectangular tooth, an end rectangular tooth, and a stator slot located between the teeth and corresponding to the target number of slots with the pole-slot ratio. S22: Determine the amplitude and phase of the first cogging force corresponding to the first motor subunit; S23: Determine the pole slot ratio and size of the remaining motor subunits based on the preset pole slot selection conditions, the amplitude and phase of the first cogging force; S24: Determine the amplitude and phase of the second cogging force corresponding to each of the remaining motor sub-units; S25: The first tooth cogging force and the second tooth cogging force are superimposed to obtain the undetermined combined tooth cogging force; S26: Determine whether the amplitude of the undetermined combined cogging force is less than the preset combined force amplitude. If not, return to S23 to select a new remaining motor subunit; if yes, proceed to the step of determining the combined cogging force corresponding to N motor subunits.

3. The design method of the permanent magnet linear motor as described in any one of claims 1 to 2, characterized in that, After determining the combined cogging force corresponding to N motor subunits, the following is also included: The third dimension of the auxiliary rectangular tooth is selected based on the combined cogging force and is located between at least one set of adjacent motor sub-units, so that the combined end force after the first end force, the second end force and the third end force corresponding to the auxiliary rectangular tooth are superimposed and the combined cogging force satisfies the preset cancellation condition within the allowable range of design error.

4. A permanent magnet linear motor, characterized in that, The permanent magnet linear motor is obtained according to the steps of the design method of the permanent magnet linear motor as described in any one of claims 1 to 3. The permanent magnet linear motor includes a mover and N motor sub-units arranged in sequence, where N is an integer greater than 1. Each motor subunit includes multiple permanent magnets disposed on the mover, and also includes an initial rectangular tooth, an intermediate rectangular tooth, an end rectangular tooth arranged in sequence, and multiple stator slots located between the rectangular teeth within the motor subunit.

5. The permanent magnet linear motor as described in claim 4, characterized in that, At least one set of adjacent motor subunits has auxiliary rectangular teeth between them.

6. The permanent magnet linear motor as described in claim 5, characterized in that, The first length of the auxiliary rectangular tooth along the x-axis is less than the second length, where the second length is the distance along the x-axis between the ending rectangular tooth of the preceding motor subunit and the initial rectangular tooth of the following motor subunit.

7. The permanent magnet linear motor as described in claim 6, characterized in that, The second length is an odd multiple of the pole pitch corresponding to the permanent magnet.

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