Permanent magnet embedded linear motor

Abstract

This invention relates to a permanent magnet embedded linear motor, belonging to the field of motor technology. The permanent magnet embedded linear motor includes: a secondary structure, which is spaced apart from the primary structure. The secondary structure includes a secondary core, within which multiple permanent magnet slots are provided. Each permanent magnet slot contains a permanent magnet. A first isolation slot is provided between two adjacent permanent magnet slots, located on the side of the slot closer to the primary structure. Along the thickness direction of the secondary core, the width of the first isolation slot at the end closer to the primary structure is greater than the width at the end farther from the primary structure. The permanent magnet embedded linear motor of this invention can reduce thrust fluctuations while ensuring thrust, resulting in smoother operation of the linear motor.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a permanent magnet embedded linear motor. Background Technology

[0002] Traditional linear motion employs a "rotary motor + ball screw" structure, using the screw to convert the rotational motion of the rotary motor into the required linear motion. However, this transmission method has many problems. With advancements in related technologies, the recently re-emerging linear servo motor (hereinafter referred to as "linear motor") effectively solves the problems of the "rotary motor + ball screw" structure: linear motors do not have a ball screw, so they are not limited by it. Linear motors offer superior performance in terms of motion length, maximum speed, maximum acceleration, positioning accuracy, and repeatability. The working principle of a linear motor can be simply understood as follows: the rotary motor is cut along its radius and stretched into a straight line. The stator becomes the stator, and the moving rotor becomes the mover. Either the stator or the mover extends along the direction of motion. In most linear motor products, the mover coil is excited by the stator permanent magnet. In existing permanent magnet motor design technology, there are two types of permanent magnet excitation side: surface-mounted and embedded. The embedded type is where the permanent magnet is inserted into the iron core on the excitation side. In this case, the air gap magnetic flux density will be affected by the iron core on the excitation side, which in turn affects the motor's thrust and thrust fluctuation and other performance parameters.

[0003] Similar to torque ripple and torque in rotating motors, thrust ripple and output thrust are core selection criteria for linear motors. Under the same conditions, greater output thrust and smaller thrust ripple are the directions for design optimization. The thrust and its ripple in a linear motor consist of cogging force and end force, which can be optimized by optimizing the cogging force and end force separately, as well as optimizing the coupling between the two. The cogging force is generated because the main pole magnetic field of the mover is generally not a strictly sinusoidal magnetic field, containing some harmonics. Moreover, due to armature reaction during motor load operation, the magnetic flux density waveform is further deteriorated, the harmonic distortion rate increases, and the ripple of the cogging effect increases. Therefore, it is necessary to correct the sinusoidal magnetic field generated by the cogging force. Summary of the Invention

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a permanent magnet embedded linear motor, which can reduce thrust fluctuations while ensuring thrust, making the linear motor operate more smoothly.

[0005] According to an embodiment of the present invention, a permanent magnet embedded linear motor includes: a secondary structure, which is arranged at intervals relative to the primary structure. The secondary structure includes a secondary core, and a plurality of permanent magnet slots are provided in the secondary core. A permanent magnet is provided in each permanent magnet slot. A first isolation slot is provided between two adjacent permanent magnet slots. The first isolation slot is located on the side of the permanent magnet slot closer to the primary structure. Along the thickness direction of the secondary core, the width of the first isolation slot at the end closer to the primary structure is greater than the width of the first isolation slot at the end farther from the primary structure.

[0006] According to an embodiment of the present invention, the permanent magnet embedded linear motor, by setting the width of the first isolation groove near the primary structure to be greater than the width of the first isolation groove away from the primary structure (i.e., "wider at the top and narrower at the bottom"), can adjust the distribution of the total length of the magnetic circuit emitted by the permanent magnet, optimize the air gap magnetic flux density waveform, thereby isolating the original direction of the magnetic circuit, guiding the new direction of the magnetic circuit, changing the magnetic circuit distribution, and thus changing the air gap magnetic field distribution. In this way, while ensuring the average thrust, the thrust fluctuation of the linear motor is reduced by reducing the cogging force.

[0007] According to an embodiment of the present invention, the permanent magnet embedded linear motor has a first isolation slot as a T-shaped slot, which simplifies the structural design of the first isolation slot.

[0008] Optionally, the distance between the side of the T-shaped head of the first isolation groove away from the permanent magnet and the permanent magnet is W11, and the thickness of the T-shaped head is W12. W11 and W12 satisfy: W12 / W11 = 0.5 to 0.9. This range is selected by adjusting the magnetic circuit reluctance simulation and experiment, which can better reduce the thrust fluctuation of the linear motor.

[0009] According to an embodiment of the present invention, the permanent magnet embedded linear motor has a length of L3 and a minimum distance of L2 between two first isolation slots located on both sides of the permanent magnet. L3 and L2 satisfy: L2 / L3 = 0.75 to 0.95. Here, L2 reflects the main length of the magnetic field lines emitted by the corresponding permanent magnet, and this length also reflects the degree of obstruction of the magnetic circuit by the first isolation slot. If this ratio is too large, it will reduce the optimization effect on the air gap magnetic flux density waveform. If this ratio is too small, it will reduce the magnetic field energy transmission. Therefore, the appropriate selection value is particularly important. Through simulation and experiment, L2 / L3 = 0.75 to 0.95 is selected, which can ensure both magnetic field energy transmission and good optimization effect on the air gap magnetic flux density waveform.

[0010] According to an embodiment of the permanent magnet embedded linear motor of the present invention, half of the maximum width of the first isolation groove is L11, and half of the difference between the maximum and minimum width of the first isolation groove is L12. L11 and L12 satisfy: L12 / L11 = 0.2 to 0.6. The width of the body structure of the first isolation groove extending from the end away from the primary structure to the end close to the primary structure can gradually increase or it can increase abruptly like a step. For example, the first isolation groove is a T-shaped groove, L11 is the length from the center line of the head of the T-shaped groove to the outermost boundary line of the head of the T-shaped groove, and L12 is the distance of the outermost boundary line on one side of the head of the T-shaped groove beyond the body of the T-shaped groove on the same side. The structure of the first isolation groove, excluding the minimum width, can optimize the waveform near the q-axis of the air gap magnetic flux density waveform. If the length of L12 is too large, it will block too much of the magnetic circuit near the q-axis, thus reducing the magnetic field energy conversion. If the length of L12 is too small, it will lose the effect of optimizing the waveform near the q-axis of the air gap magnetic flux density waveform. Therefore, the appropriate value range is particularly important. Through simulation and experiment, L12 / L11 = 0.2 to 0.6 was selected, which can ensure that the magnetic field energy conversion is not significantly reduced while achieving a good effect of optimizing the waveform near the q-axis of the air gap magnetic flux density waveform.

[0011] The permanent magnet embedded linear motor according to an embodiment of the present invention further includes: a set of second isolation slots, the second isolation slots being disposed on the secondary iron core and located on the side of the permanent magnet slot close to the primary structure, the two second isolation slots being respectively located between the first isolation slots on both sides of the permanent magnet and the central axis of the permanent magnet, which can further adjust the distribution of the total length of the magnetic path emitted by the permanent magnet and further optimize the air gap magnetic flux density waveform.

[0012] Optionally, the second isolation groove is composed of two vertically staggered rectangular grooves stacked and connected, or the isolation groove is a parallelogram groove. The end of the second isolation groove closer to the primary structure is closer to the central axis of the permanent magnet than the end of the second isolation groove further away from the primary structure. The second isolation groove can block and adjust the magnetic circuit of the permanent magnet, guide the magnetic circuit to separate along both sides of the second isolation groove, better adjust the air gap magnetic flux density waveform, make the air gap distribution more uniform, and reduce fluctuations.

[0013] Optionally, the maximum width of the second isolation groove is L21, and the minimum width of the second isolation groove is L22. L21 and L22 satisfy: L22 / L21 = 0.2 to 0.5. Since the second isolation groove reflects the adjustment of the amplitude of the permanent magnet's magnetic circuit rather than the adjustment of the total energy of the magnetic field emitted by the permanent magnet, by selecting L22 / L21 = 0.2 to 0.5 through simulation and experiment, the air gap magnetic flux density waveform can be better adjusted, making the air gap distribution more uniform and the fluctuation smaller.

[0014] Optionally, the second isolation groove is composed of two vertically staggered rectangular grooves stacked and connected. The height of the second isolation groove extending beyond the permanent magnet in the direction of the primary structure is W21, and the height of the part of the second isolation groove near the central axis of the permanent magnet is W22. W21 and W22 satisfy: W22 / W21=0.35~0.75. W22 / W21 reflects the effect of magnetic reluctance and magnetic circuit adjustment. After simulation and experiment, W22 / W21=0.35~0.75 was selected, which can better adjust the air gap magnetic flux density waveform, make the air gap distribution more uniform, and reduce fluctuations.

[0015] Optionally, the shortest distance of a set of second isolation slots is L1, and the length of the permanent magnet is L3, where L1 and L3 satisfy: L1 / L3 = 0.4 to 0.8. The ratio of L1 / L3 ultimately affects the effect of magnetic circuit adjustment converging towards the center line of the magnetic poles and the effect of correcting the air gap magnetic flux density waveform. Therefore, after simulation and experimentation, L1 / L3 = 0.4 to 0.8 was selected to achieve better effect of magnetic circuit adjustment converging towards the center line of the magnetic poles and better effect of correcting the air gap magnetic flux density waveform.

[0016] The permanent magnet embedded linear motor according to an embodiment of the present invention further includes: a third isolation slot and / or a fourth isolation slot. The third and fourth isolation slots are stacked at intervals along the thickness direction of the secondary core and are both located on the side of the permanent magnet closer to the primary structure. The central axis of the third isolation slot and the central axis of the fourth isolation slot coincide with the central axis of the permanent magnet. The third isolation slot is close to the permanent magnet slot, and the fourth isolation slot is close to the primary structure. Due to the influence of the positional relationship between the stator secondary structure and the mover primary structure, or the positional relationship between the mover secondary structure and the stator primary structure, the distribution of magnetic field lines at the center of the magnetic pole varies greatly at different times, resulting in large fluctuations during operation. To reduce the influence of position on the distribution of magnetic field lines near the center line of the magnetic pole, the peak-like distortion of the air gap magnetic flux density waveform is adjusted to make the air gap distribution more uniform and the fluctuations smaller.

[0017] Optionally, both the third and fourth isolation slots are rectangular slots, which simplifies the structural design of the third and fourth isolation slots.

[0018] Optionally, the length of the third isolation slot is L03, the length of the fourth isolation slot is L04, and the length of the permanent magnet is L3. L03 and L3 satisfy: L03 / L3 = 0.05–0.25; L04 and L3 satisfy: L04 / L3 = 0.05–0.25. Both the third and fourth isolation slots optimize the portion of the air gap magnetic flux density waveform near the magnetic pole centerline. The lengths of the third and fourth isolation slots and their ratio to the length of the permanent magnet reflect the degree of shielding of the magnetic circuit by the isolation slots. Excessive shielding will reduce the thrust of the linear motor; insufficient shielding negates the purpose of optimizing the air gap magnetic flux density waveform. Furthermore, because the fourth isolation slot is closer to the air gap than the third, it has a greater impact on the air gap magnetic flux density; therefore, the value of L04 should be less than that of L03.

[0019] Optionally, the first isolation groove is a T-shaped groove, with the distance from the permanent magnet to the side of the T-shaped head of the first isolation groove away from the permanent magnet being W11. The thickness of the third isolation groove is W03, and the thickness of the fourth isolation groove is W04. W03 and W11 satisfy: W03 / W11 = 0.05~0.25; W04 and W11 satisfy: W04 / W11 = 0.2~0.4. The third and fourth isolation grooves are both optimizations of the portion of the air gap magnetic flux density waveform near the center line of the magnetic pole. The length of the third and fourth isolation grooves and their ratio to the length of the permanent magnet reflect the degree of shielding of the magnetic circuit by the isolation groove. If there is too much shielding, the thrust of the linear motor will decrease; if there is too little shielding, the optimization of the air gap magnetic flux density waveform is lost. The width of the third isolation slot affects its magnetic reluctance, and the width of the fourth isolation slot affects its magnetic reluctance. Magnetic reluctance characterizes the isolation effect of the isolation slot on the magnetic circuit. Because the fourth isolation slot is closer to the air gap than the third isolation slot, it has a greater impact on the air gap magnetic flux density. Therefore, the width of the fourth isolation slot should be smaller than that of the third isolation slot. Thus, through simulation and experimentation, W03 / W11 = 0.05~0.25 and W04 / W11 = 0.2~0.4 were selected, which can effectively optimize the air gap magnetic flux density waveform without significantly reducing the linear motor thrust.

[0020] Compared with the prior art, the above-mentioned technical solution provided by the embodiments of the present invention has the following advantages: the permanent magnet embedded linear motor of this application can reduce the fluctuation of thrust without significantly reducing the thrust or even increasing the average thrust, so that the linear motor runs more smoothly. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a permanent magnet embedded linear motor according to an embodiment of the present invention;

[0024] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0025] Figure 3 A cross-sectional view of the secondary structure of a permanent magnet embedded linear motor according to an embodiment of the present invention;

[0026] Figure 4 For the secondary structure of the permanent magnet embedded linear motor according to an embodiment of the present invention and Figure 3 Same sectional view;

[0027] Figure 5 For the secondary structure of the permanent magnet embedded linear motor according to an embodiment of the present invention and Figure 3 Same sectional view;

[0028] Figure 6 The thrust curve of the permanent magnet embedded linear motor in this embodiment of the invention is compared with the thrust curve of a linear motor in the prior art.

[0029] Figure label:

[0030] Linear motor 1,

[0031] Primary structure 10, primary iron core 11, winding coil 12,

[0032] Secondary structure 20,

[0033] Secondary core 21, permanent magnet slot 212, first isolation slot 214, second isolation slot 216, third isolation slot 217, fourth isolation slot 218

[0034] permanent magnet 22,

[0035] The thrust curve a of the permanent magnet embedded linear motor 1 of this application, and the thrust curve b of the permanent magnet embedded linear motor in the prior art. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] The permanent magnet embedded linear motor 1 according to an embodiment of the present invention is described below with reference to the accompanying drawings.

[0038] like Figure 1 and Figure 2 As shown, the permanent magnet embedded linear motor 1 according to an embodiment of the present invention includes: a primary structure 10 and a secondary structure 20.

[0039] Specifically, the primary structure 10 includes a primary iron core 11 and a winding coil 12 disposed on the primary iron core 11; the secondary structure 20 is disposed at a distance from the primary structure 10, the secondary structure 20 includes a secondary iron core 21, the secondary iron core 21 is provided with a plurality of permanent magnet slots 212, each permanent magnet slot 212 is provided with a permanent magnet 22, and a first isolation slot 214 is provided between two adjacent permanent magnet slots 212. The first isolation slot 214 is located on the side of the permanent magnet slot 212 closer to the primary structure 10. Along the thickness direction of the secondary iron core 21, the width of the end of the first isolation slot 214 closer to the primary structure 10 is greater than the width of the end of the first isolation slot 214 away from the primary structure 10.

[0040] The secondary core 21 can be made of soft magnetic materials, such as silicon steel sheets.

[0041] It should be noted that the primary structure 10 can be the stator and the secondary structure 20 can be the mover; alternatively, the primary structure 10 can be the mover and the secondary structure 20 can be the stator. This application does not impose any restrictions; the following is an example illustrating the use of the secondary structure 20 as the stator.

[0042] In detail, when the permanent magnet 22 is inserted into the secondary core 21 on the excitation side, the air gap magnetic flux density is affected by the secondary core 21. The distribution of magnetic field lines at the center of the magnetic pole varies greatly at different times, resulting in significant fluctuations during operation. The first isolation slot 214 generates magnetic resistance. By setting the first isolation slot 214, the total length distribution of the magnetic path emitted by the permanent magnet 22 can be adjusted. In the direction closer to the primary structure 10, the first isolation slot 214 further shortens the length of the magnetic path of the permanent magnet 22, making the distribution of magnetic field lines near the center line of the magnetic pole less affected by position. This optimizes the air gap magnetic flux density waveform, thereby isolating the original direction of the magnetic path, guiding a new direction of the magnetic path, changing the magnetic path distribution, and thus changing the air gap magnetic field distribution.

[0043] like Figure 6 As shown in the figure, curve a is the thrust curve of the permanent magnet embedded linear motor 1 of this application, which can reflect the thrust and thrust fluctuation of the permanent magnet embedded linear motor 1 of this application. Curve b is the thrust curve of the linear motor in the prior art, which can reflect the thrust and thrust fluctuation of the linear motor in the prior art. It can be clearly seen that the thrust of the linear motor 1 of this application is not only not reduced but slightly increased compared with the prior art, while the thrust fluctuation is significantly reduced.

[0044] In addition, it should be noted that each permanent magnet slot 212 may contain one permanent magnet 22 or multiple permanent magnets 22. Similarly, the shape of the permanent magnet 22 may be a variety of shapes, such as rectangle, parallelogram, arc, rhombus, polygon, and combinations thereof, and this application does not impose any restrictions.

[0045] In addition, the first isolation groove 214 can be an air groove without any filler; or the first isolation groove 214 can be filled with magnetic shielding material to achieve a better magnetic shielding effect.

[0046] It should also be added that the width of the body structure of the first isolation groove 214 extending from the end away from the primary structure 10 to the end close to the primary structure 10 can gradually increase or it can increase abruptly like a step, and this application does not impose any restrictions.

[0047] According to an embodiment of the present invention, the permanent magnet embedded linear motor 1 has a first isolation groove 214 whose width at the end near the primary structure 10 is greater than the width at the end away from the primary structure 10. That is, in the direction gradually approaching the primary structure 10, the end near the primary structure 10 is "upper" and the end away from the primary structure 10 is "lower", presenting a "wider at the top and narrower at the bottom" shape. This allows the first isolation groove 214 to adjust the distribution of the total length of the magnetic path emitted by the permanent magnet 22, optimize the air gap magnetic flux density waveform, isolate the original direction of the magnetic path, guide the new direction of the magnetic path, change the magnetic path distribution, and thus change the air gap magnetic field distribution. In this way, while ensuring the average thrust value, the thrust fluctuation of the linear motor 1 is reduced by reducing the cogging force.

[0048] According to an embodiment of the present invention, the permanent magnet embedded linear motor 1 has a first isolation groove 214 as a T-shaped groove, which simplifies the structural design of the first isolation groove 214.

[0049] like Figure 3As shown, optionally, the distance between the side of the T-shaped head of the first isolation groove 214 away from the permanent magnet 22 and the permanent magnet 22 is W11, and the thickness of the T-shaped head is W12. W11 and W12 satisfy: W12 / W11 = 0.5~0.9. This range is selected by adjusting the magnetic circuit reluctance simulation and experiment, which can better reduce the thrust fluctuation of the linear motor 1.

[0050] like Figure 4 As shown, in the permanent magnet embedded linear motor 1 according to an embodiment of the present invention, the length of the permanent magnet 22 is L3, and the shortest distance between the two first isolation slots 214 located on both sides of the permanent magnet 22 is L2. L3 and L2 satisfy: L2 / L3 = 0.75~0.95, where L2 reflects the main length of the magnetic field lines emitted by the corresponding permanent magnet 22. This length also reflects the degree of blockage of the magnetic circuit by the first isolation slots 214. If this ratio is too large, it will reduce the optimization effect on the air gap magnetic flux density waveform. If this ratio is too small, it will reduce the magnetic field energy transmission. Therefore, the appropriate selection value is particularly important. Through simulation and experiment, L2 / L3 = 0.75~0.95 is selected, which can ensure both magnetic field energy transmission and good optimization effect on the air gap magnetic flux density waveform.

[0051] like Figure 3 As shown, in the permanent magnet embedded linear motor 1 according to an embodiment of the present invention, half of the maximum width of the first isolation groove 214 is L11, and half of the difference between the maximum and minimum width of the first isolation groove 214 is L12. L11 and L12 satisfy: L12 / L11 = 0.2~0.6. The width of the body structure of the first isolation groove 214 extending from the end away from the primary structure 10 to the end close to the primary structure 10 can gradually increase or it can increase abruptly like a step. For example, for Figure 3 In the embodiment shown, the first isolation groove 214 is a T-shaped groove. L11 is the length from the center line of the head of the T-shaped groove to the outermost boundary line of the head of the T-shaped groove, and L12 is the distance from the outermost boundary line on one side of the head of the T-shaped groove to the main body of the T-shaped groove on the same side. The maximum width of the first isolation groove 214 minus the minimum width can optimize the waveform near the q-axis of the air gap magnetic flux density waveform. If the length of L12 is too large, it will block too much of the magnetic circuit near the q-axis, thereby reducing the magnetic field energy conversion. If the length of L12 is too small, it will lose the effect of optimizing the waveform near the q-axis of the air gap magnetic flux density waveform. Therefore, an appropriate value range is particularly important. Through simulation and experimentation, L12 / L11 = 0.2 to 0.6 was selected, which can ensure that the magnetic field energy conversion is not significantly reduced while achieving a good effect of optimizing the waveform near the q-axis of the air gap magnetic flux density waveform.

[0052] like Figure 1 and Figure 2As shown, the permanent magnet embedded linear motor 1 according to an embodiment of the present invention further includes: a set of second isolation slots 216. The second isolation slots 216 are disposed on the secondary iron core 21 and located on the side of the permanent magnet slot 212 near the primary structure 10. The two second isolation slots 216 are respectively located between the first isolation slots 214 on both sides of the permanent magnet 22 and the central axis of the permanent magnet 22, which can further adjust the distribution of the total length of the magnetic path emitted by the permanent magnet 22 and further optimize the air gap magnetic flux density waveform. In addition, the second isolation slots 216 can be air slots without any filler; or the second isolation slots 216 can be filled with magnetic shielding material to achieve a better magnetic shielding effect.

[0053] like Figure 1 and Figure 2 As shown, optionally, the second isolation groove 216 is composed of two vertically staggered rectangular grooves stacked and connected, or the isolation groove is a parallelogram groove. The end of the second isolation groove 216 closer to the primary structure 10 is closer to the central axis of the permanent magnet 22 than the end of the second isolation groove 216 further away from the primary structure 10. The second isolation groove 216 can block and adjust the magnetic circuit of the permanent magnet 22, guide the magnetic circuit to separate along both sides of the second isolation groove 216, better adjust the air gap magnetic flux density waveform, make the air gap distribution more uniform, and reduce fluctuations.

[0054] like Figure 4 As shown, optionally, the maximum width of the second isolation groove 216 is L21, and the minimum width of the second isolation groove 216 is L22. L21 and L22 satisfy: L22 / L21 = 0.2~0.5. Since the second isolation groove 216 reflects the adjustment of the amplitude of the magnetic circuit of the permanent magnet 22 rather than the adjustment of the total energy of the magnetic field emitted by the permanent magnet 22, by selecting L22 / L21 = 0.2~0.5 through simulation and experiment, the air gap magnetic flux density waveform can be better adjusted, making the air gap distribution more uniform and the fluctuation smaller.

[0055] like Figure 3 As shown, optionally, the second isolation groove 216 is composed of two vertically staggered rectangular grooves stacked and connected. The height of the portion of the second isolation groove 216 extending beyond the permanent magnet 22 in the direction of the primary structure 10 is W21, and the height of the portion of the second isolation groove 216 near the central axis of the permanent magnet 22 is W22. W21 and W22 satisfy: W22 / W21=0.35~0.75. W22 / W21 reflects the effect of magnetic reluctance and magnetic circuit adjustment. After simulation and experiment, W22 / W21=0.35~0.75 was selected, which can better adjust the air gap magnetic flux density waveform, make the air gap distribution more uniform, and reduce fluctuations.

[0056] like Figure 4As shown, optionally, the shortest distance of a set of second isolation slots 216 is L1, and the length of the permanent magnet 22 is L3. L1 and L3 satisfy: L1 / L3 = 0.4 to 0.8. The ratio of L1 / L3 can ultimately affect the effect of magnetic circuit adjustment converging towards the magnetic pole centerline and the effect of correcting the air gap magnetic flux density waveform. Therefore, after simulation and experimentation, L1 / L3 = 0.4 to 0.8 is selected to make the effect of magnetic circuit adjustment converging towards the magnetic pole centerline and the effect of correcting the air gap magnetic flux density waveform better.

[0057] like Figure 1 and Figure 2 As shown, the permanent magnet embedded linear motor 1 according to an embodiment of the present invention further includes: a third isolation groove 217 and / or a fourth isolation groove 218. The third isolation groove 217 and the fourth isolation groove 218 are both located on the side of the permanent magnet 22 close to the primary structure 10. The central axis of the third isolation groove 217 and the central axis of the fourth isolation groove 218 coincide with the central axis of the permanent magnet 22. Linear motor 1 can be configured with only the third isolation slot 217; or with only the fourth isolation slot 218; or with both the third and fourth isolation slots 217 and 218. When both are configured, the third and fourth isolation slots 217 and 218 are stacked at intervals along the thickness direction of the secondary core 21, with the third isolation slot 217 closer to the permanent magnet slot 212 and the fourth isolation slot 218 closer to the primary structure 10. Due to the positional relationship between the stator secondary structure 20 and the mover primary structure 10, or between the mover secondary structure 20 and the stator primary structure 10, the distribution of magnetic field lines at the center of the magnetic pole varies significantly at different times, resulting in large fluctuations during operation. To minimize the positional influence on the distribution of magnetic field lines near the center of the magnetic pole, the peak-like distortion of the air gap magnetic flux density waveform is adjusted to make the air gap distribution more uniform and reduce fluctuations.

[0058] It should be noted that the shapes of the third isolation groove 217 and the fourth isolation groove 218 can be set as needed, and this application does not impose any restrictions.

[0059] Additionally, it should be noted that the third isolation groove 217 and the fourth isolation groove 218 can be air grooves, without any filler; or the third isolation groove 217 and the fourth isolation groove 218 can be filled with magnetic shielding material to achieve a better magnetic shielding effect; or one of the third isolation groove 217 and the fourth isolation groove 218 can be an air groove and the other can be filled with magnetic shielding material.

[0060] Optionally, both the third isolation groove 217 and the fourth isolation groove 218 are rectangular grooves, which simplifies the structural design of the third isolation groove 217 and the fourth isolation groove 218.

[0061] like Figure 5As shown, optionally, the length of the third isolation slot 217 is L03, the length of the fourth isolation slot 218 is L04, and the length of the permanent magnet 22 is L3. L03 and L3 satisfy: L03 / L3 = 0.05~0.25; L04 and L3 satisfy: L04 / L3 = 0.05~0.25. Both the third isolation slot 217 and the fourth isolation slot 218 optimize the portion of the air gap magnetic flux density waveform near the magnetic pole centerline. The lengths of the third isolation slot 217 and the fourth isolation slot 218, and their ratio to the length of the permanent magnet 22, reflect the degree of obstruction of the magnetic circuit by the isolation slots. If there is too much obstruction, the thrust of the linear motor 1 will decrease; if there is too little obstruction, the optimization of the air gap magnetic flux density waveform is lost. Furthermore, because the fourth isolation slot 218 is closer to the air gap than the third isolation slot 217, the fourth isolation slot 218 has a greater impact on the air gap magnetic flux density; therefore, the value of L04 should be less than L03.

[0062] like Figure 3 and Figure 5 As shown, optionally, the first isolation groove 214 is a T-shaped groove. The distance between the side of the T-shaped head of the first isolation groove 214 away from the permanent magnet 22 and the permanent magnet 22 is W11. The thickness of the third isolation groove 217 is W03, and the thickness of the fourth isolation groove 218 is W04. W03 and W11 satisfy: W03 / W11 = 0.05~0.25; W04 and W11 satisfy: W04 / W11 = 0.2~0.4. The third isolation groove 217 and the fourth isolation groove 218 are both optimizations of the part of the air gap magnetic flux density waveform near the center line of the magnetic pole. The length of the third isolation groove 217 and the fourth isolation groove 218 and their ratio to the length of the permanent magnet 22 reflect the degree of shielding of the magnetic circuit by the isolation groove. If there is too much shielding, the thrust of the linear motor 1 will decrease; if there is too little shielding, the optimization of the air gap magnetic flux density waveform will be lost. The width of the third isolation slot 217 affects its magnetic reluctance, and the width of the fourth isolation slot 218 affects its magnetic reluctance. Magnetic reluctance characterizes the isolation effect of the isolation slot on the magnetic circuit. Because the fourth isolation slot 218 is closer to the air gap than the third isolation slot 217, it has a greater impact on the air gap magnetic flux density. Therefore, the width of the fourth isolation slot 218 should be smaller than that of the third isolation slot 217. Thus, through simulation and experimentation, W03 / W11 = 0.05~0.25 and W04 / W11 = 0.2~0.4 were selected, which can effectively optimize the air gap magnetic flux density waveform without significantly reducing the thrust of the linear motor 1.

[0063] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, features defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0064] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0065] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A permanent magnet embedded linear motor, characterized in that, include: A primary structure, the primary structure comprising a primary iron core and a winding coil disposed on the primary iron core; The secondary structure is arranged at a distance from the primary structure. The secondary structure includes a secondary core with multiple permanent magnet slots inside. Each permanent magnet slot contains a permanent magnet. A first isolation slot is provided between two adjacent permanent magnet slots. The first isolation slot is located on the side of the permanent magnet slot closer to the primary structure. Along the thickness direction of the secondary core, the width of the first isolation slot at the end closer to the primary structure is greater than the width of the end of the first isolation slot away from the primary structure. The first isolation groove is a T-shaped groove. The T-shaped head of the first isolation groove is completely located between the permanent magnet and the primary structure. The distance between the side of the T-shaped head of the first isolation groove away from the permanent magnet and the permanent magnet is W11. The thickness of the T-shaped head is W12. W11 and W12 satisfy: W12 / W11=0.5~0.

9.

2. The permanent magnet embedded linear motor according to claim 1, characterized in that, The length of the permanent magnet is L3, and the shortest distance between the two first isolation slots located on both sides of the permanent magnet is L2. L3 and L2 satisfy: L2 / L3=0.75~0.

95.

3. The permanent magnet embedded linear motor according to claim 1, characterized in that, The maximum width of the first isolation groove is half of L11, and the difference between the maximum width and the minimum width of the first isolation groove is half of L12. L11 and L12 satisfy: L12 / L11=0.2~0.

6.

4. The permanent magnet embedded linear motor according to claim 1, characterized in that, Also includes: A set of second isolation slots is provided on the secondary iron core and located on the side of the permanent magnet slot close to the primary structure. The two second isolation slots are respectively located between the first isolation slots on both sides of the permanent magnet and the central axis of the permanent magnet.

5. The permanent magnet embedded linear motor according to claim 4, characterized in that, The second isolation groove is formed by two vertically staggered rectangular grooves stacked and connected, or the isolation groove is a parallelogram groove, and the end of the second isolation groove closer to the primary structure is closer to the central axis of the permanent magnet than the end of the second isolation groove further away from the primary structure.

6. The permanent magnet embedded linear motor according to claim 4, characterized in that, The maximum width of the second isolation groove is L21, and the minimum width of the second isolation groove is L22. L21 and L22 satisfy: L22 / L21=0.2~0.

5.

7. The permanent magnet embedded linear motor according to claim 4, characterized in that, The second isolation groove is composed of two vertically staggered rectangular grooves stacked and connected. The height of the second isolation groove extending beyond the permanent magnet in the direction of the primary structure is W21, and the height of the portion of the second isolation groove near the central axis of the permanent magnet is W22. W21 and W22 satisfy: W22 / W21=0.35~0.

75.

8. The permanent magnet embedded linear motor according to claim 4, characterized in that, The shortest distance between the second set of isolation slots is L1, and the length of the permanent magnet is L3. L1 and L3 satisfy: L1 / L3 = 0.4 to 0.

8.

9. The permanent magnet embedded linear motor according to claim 1, characterized in that, Also includes: The third and fourth isolation grooves are both located on the side of the permanent magnet closer to the primary structure, and the central axis of the third and fourth isolation grooves coincides with the central axis of the permanent magnet.

10. The permanent magnet embedded linear motor according to claim 9, characterized in that, Both the third and fourth isolation grooves are rectangular grooves.

11. The permanent magnet embedded linear motor according to claim 10, characterized in that, The length of the third isolation groove is L03, the length of the fourth isolation groove is L04, and the length of the permanent magnet is L3. L03 and L3 satisfy: L03 / L3=0.05~0.25; L04 and L3 satisfy: L04 / L3=0.05~0.

25.

12. The permanent magnet embedded linear motor according to claim 10, characterized in that, The first isolation groove is a T-shaped groove. The distance between the side of the T-shaped head of the first isolation groove away from the permanent magnet and the permanent magnet is W11. The thickness of the third isolation groove is W03, and the thickness of the fourth isolation groove is W04. W03 and W11 satisfy: W03 / W11=0.05~0.25; W04 and W11 satisfy: W04 / W11=0.2~0.4.

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