A magnetic levitation planar motor workbench with double-layer winding coarse and fine drive

Abstract

The present invention discloses a magnetic levitation planar motor workbench with a coarse and fine drive of a double-layer winding, belonging to the technical field of planar motors. The workbench comprises a stator and a mover. The vertically magnetized permanent magnets and the horizontally magnetized permanent magnets in the stator are arranged in a Halbach manner; the mover is located on the reinforcing side of the air gap magnetic field above the stator. The mover adopts a double-layer coil winding of unequal height, and the height of the upper first winding is smaller than that of the lower second winding. Each layer of winding can generate driving forces in six directions to achieve six-degree-of-freedom drive. In the variable speed motion stage, a larger driving force is generated by the lower second winding to achieve high acceleration and low-precision motion control; in the uniform linear motion stage, a driving force with higher precision and smaller fluctuation is generated by the upper first winding to achieve uniform speed motion. The present invention can reduce the output fluctuation during the motion process, improve the motion accuracy, and the workbench has good stability, small tracking error, and high positioning accuracy.

Description

Technical Field

[0001] The present invention belongs to the technical field of planar motors, and more particularly, relates to a magnetic levitation planar motor workbench with a double-layer winding coarse and fine drive. Background Art

[0002] The advancement of nano-precision machining equipment, such as integrated circuits, micro-electromechanical systems (MEMS), and space optical components, has placed ever-higher demands on the travel, acceleration, and positioning accuracy of motion platforms. As key equipment in the IC manufacturing process, lithography machines integrate cutting-edge technologies, including optical, electrical, magnetic, and thermal technologies. Magnetic levitation planar motors, a core component of next-generation lithography machines, enable precise motion control over long travel distances.

[0003] In semiconductor manufacturing, traditional ultra-precision worktables typically utilize macro-micro actuation. Conventional multi-degree-of-freedom motion platforms typically employ a combination of multiple actuators, such as air bearings, ball screws, linear motors, piezoelectric ceramics, and flexible hinges. During the processing and assembly stages, manufacturing tolerances and assembly errors inevitably affect motion characteristics. Furthermore, the need for ventilation and frictional damping during operation significantly limits their scope of application and often suffers from structural complexity. For example, while the patent [A Two-Degree-of-Freedom High-Precision, Long-Stroke Air-Floating Worktable, CN103592824B] achieves long-stroke motion and high-precision positioning, it requires highly flat marble as the air bearing guides and linear motors to provide two degrees of freedom. Magnetic levitation planar motors, on the other hand, utilize the Lorentz force to achieve six-degree-of-freedom motion control. Their simple structure, high integration density, vacuum compatibility, low friction, no need for lubrication, and long stroke make them a key research area.

[0004] Magnetic levitation planar motors utilize the Lorentz force generated by a current-carrying conductor in a magnetic field to provide driving force and torque. Therefore, to achieve high-acceleration, high-speed precision motion control, high requirements are placed on the fluctuation range of the driving force. For example, the patent [A Permanent Magnet Synchronous Magnetic Levitation Planar Motor, CN102097982B] optimizes the design of the permanent magnet array, with permanent magnets of various shapes and magnetization directions. However, in actual processing, special-shaped permanent magnets are difficult to process, placing high demands on the bonding process, making it difficult to produce a magnetic field distribution with good sinusoidal characteristics. Furthermore, the output fluctuates significantly during motion, resulting in poor stability, large tracking errors, and low positioning accuracy.

[0005] Therefore, how to reduce the output fluctuation of the magnetic levitation planar motor during movement and improve the motion control accuracy has become a technical challenge in this field. Summary of the Invention

[0006] In response to the above-mentioned defects or improvement needs of the prior art, the present invention provides a magnetic levitation planar motor workbench with a coarse and fine drive of a double-layer winding. Its purpose is to reduce the output fluctuation during the movement of the magnetic levitation planar motor and improve the movement accuracy through the design of a double-layer winding with unequal heights in the mover and a two-dimensionally arranged permanent magnet array in the stator, thereby solving the technical problem of large output fluctuation during the movement of the existing magnetic levitation planar motor.

[0007] To achieve the above objectives, the present invention provides the following technical solutions:

[0008] A magnetic levitation planar motor workbench with double-layer winding coarse and fine drive, the workbench includes a stator and a mover,

[0009] The stator includes a base, and a plurality of vertically magnetized permanent magnets and a plurality of horizontally magnetized permanent magnets arranged in grooves of the base in a Halbach arrangement;

[0010] The mover is located on the reinforcing side of the magnetic field generated by the stator; the mover includes a first winding and a second winding stacked on top of the first winding, wherein the height of the first winding is smaller than the height of the second winding; the first winding and the second winding each include a plurality of coils capable of generating driving forces in two directions when energized, such that the first winding and the second winding each have a six-degree-of-freedom driving force and a driving torque; the shape of the mover's perimeter is square or approximately square. This approximately square shape means that the aspect ratio of the smallest rectangle that can accommodate the mover's perimeter is in the range [0.9, 1.1].

[0011] Preferably, the height ratio of the first winding to the second winding is in the range of [0.2, 0.6].

[0012] Preferably, the first winding includes four groups of first single-phase windings arranged in 2 rows and 2 columns, the first single-phase winding includes a rectangular coils arranged in parallel with equal spacing, and the long sides of the rectangular coils of each two adjacent groups of first single-phase windings are perpendicular to each other;

[0013] The second winding has the same structure as the first winding and only differs in height. The rectangular coils in the first winding and the rectangular coils in the second winding are stacked one by one, and the long sides and short sides of the upper and lower rectangular coils are aligned, so that the upper and lower rectangular coils are completely aligned.

[0014] Preferably, the first winding includes three groups of second single-phase windings, and the second single-phase winding includes b rectangular coils stacked in a stepped manner, wherein one group of the second single-phase windings is placed flat in the middle, and the other two groups of the second single-phase windings are placed vertically on the upper left and lower right steps of the middle second single-phase winding, respectively, and are in contact with each other at the step connection of the middle second single-phase winding;

[0015] The second winding has the same structure as the first winding but a different height. The orientation of the second winding is obtained by rotating the first winding 90° counterclockwise around its own center.

[0016] Preferably, the first winding comprises c rows, each row having d rectangular coils, the short sides of adjacent rectangular coils in each row are connected, and adjacent rows are staggered left and right;

[0017] The second winding has the same structure as the first winding but a different height. The long side of the rectangular coil in the first winding and the long side of the rectangular coil in the second winding are perpendicular to each other.

[0018] Preferably, the long sides of the rectangular coils in the first winding and the second winding form an angle of 45°±1° with the right-angled side of the vertically magnetized permanent magnet.

[0019] Preferably, the first winding and the second winding each include e rows*e columns of circular coils, and the circular coils in the first winding and the second winding are stacked in upper and lower concentric circles in a one-to-one correspondence.

[0020] Preferably, in the first single-phase winding, the long side of the rectangular coil is four times the pole pitch, and the center distance between adjacent rectangular coils is 4 / 3 times the pole pitch.

[0021] Preferably, the workbench further includes a vacuum cover, and the mover is arranged inside the vacuum cover.

[0022] Preferably, the vertically magnetized permanent magnet is square, and the horizontally magnetized permanent magnet is rectangular.

[0023] The above a, b, c, d, and e are all positive integers greater than 1.

[0024] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0025] 1. The present invention provides a double-layer winding coarse and fine driven magnetic levitation planar motor workbench, in which the stator is composed of a plurality of vertically magnetized permanent magnets and a plurality of horizontally magnetized permanent magnets arranged in a Halbach manner to form a permanent magnet array structure, so that the magnetic field above the permanent magnet is enhanced and the magnetic field below is weakened, and the mover is located on the enhanced side of the air gap magnetic field above the stator. The mover adopts a double-layer coil winding of unequal heights, namely a first winding and a second winding, and the first winding is located above the second winding and has a height less than that of the second winding. The first winding and the second winding both contain a plurality of coils having driving forces in two directions when energized, and each coil can generate driving forces in two directions. After the first winding and the second winding are energized and decoupled through current, they interact with the air gap magnetic field generated by the stator permanent magnet array, and can each generate driving forces and driving torques in six directions, thereby realizing six-degree-of-freedom drive. During the variable speed motion stage, the second winding of the lower layer generates a larger driving force to achieve acceleration and deceleration motion, realizing high acceleration and low precision motion control; during the uniform linear motion stage, the first winding of the upper layer generates a driving force with higher precision and smaller fluctuation to achieve uniform speed motion, and the high-speed and high-precision motion control goal is achieved through this coarse and fine drive scheme; this double-layer winding structure can reduce the output fluctuation during the motion process, improve the motion accuracy, and the workbench has good stability, small tracking error, and high positioning accuracy, providing reliable technical support for ultra-precision manufacturing fields such as semiconductor processing.

[0026] 2. The double-layer winding coarse and fine driven magnetic levitation planar motor workbench provided by the present invention adopts double-layer coil windings of unequal heights to pass different currents in different movement stages to provide the target driving force, which can effectively reduce the heat dissipation of the coil and avoid the coil heating affecting the structural characteristics and reducing the movement accuracy.

[0027] 3. The double-layer winding coarse and fine drive magnetic levitation planar motor workbench provided by the present invention is designed with a height ratio h of the first winding and the second winding in the double-layer winding structure. ration The range is [0.2, 0.6]. When the height ratio is within this range, the coil in the upper first winding is not forced to pass a large current to generate the desired force and torque due to the low magnetic field strength, which will cause the coil to heat up too much. At the same time, compared with the coil in the lower second winding, the high-order harmonic content of the magnetic field strength at the coil in the upper first winding is lower, and the generated driving force and driving torque fluctuate less, which is conducive to achieving the goal of smooth motion control.

[0028] 4. The double-layer winding coarse and fine drive magnetic levitation planar motor workbench provided by the present invention provides four coil topologies of the first / second winding, that is, it provides four specific implementation schemes of the magnetic levitation planar motor workbench, which has a simple structure and is easy to implement and apply.

[0029] 5. The double-layer winding coarse and fine driven magnetic levitation planar motor workbench provided by the present invention utilizes the Lorentz force generated by the current-carrying conductor in the magnetic field to directly drive the moving parts to move without lubrication and friction. The vacuum cover installed on the outside of the mover makes the workbench vacuum-compatible while avoiding the impact of coil heating. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a three-dimensional schematic diagram of a magnetic levitation planar motor workbench with double-layer winding coarse and fine drive in Example 1 of the present invention;

[0031] Figure 2 1. It is a top view of the permanent magnet array structure and auxiliary lines of the stator in Example 1 of the present invention;

[0032] Figure 3 This is an isometric view of the double-layer winding of the mover in Example 1 of the present invention;

[0033] Figure 4 1 is a top view of the double-layer winding of the mover in Example 2 of the present invention;

[0034] Figure 5 1. It is a top view of the double-layer winding of the mover in embodiment 3 of the present invention;

[0035] Figure 6 It is a top view of the double-layer winding of the mover in Example 4 of the present invention.

[0036] Figure 7 It is a path planning diagram in a semiconductor processing process in a preferred embodiment of the present invention;

[0037] Figure 8 is a side view of the permanent magnet array structure and auxiliary lines in an embodiment of the present invention;

[0038] FIG9( a ) is a diagram showing the horizontal component of the magnetic field intensity in the air gap magnetic field in a preferred embodiment of the present invention;

[0039] FIG9( b ) is a spectrum diagram of the horizontal component of the magnetic field intensity after FFT transformation in a preferred embodiment of the present invention;

[0040] FIG10( a ) is a diagram showing the vertical component of the magnetic field intensity in the air gap magnetic field in a preferred embodiment of the present invention;

[0041] FIG10( b ) is a spectrum diagram of the vertical component of the magnetic field intensity after FFT transformation in a preferred embodiment of the present invention;

[0042] Figure 11 1 is a side view of a magnetic levitation planar motor with a double-layer winding coarse and fine drive according to a preferred embodiment of the present invention;

[0043] Figure 12 3 is a total harmonic distortion diagram of the magnetic field strength at different heights in the air gap magnetic field in a preferred embodiment of the present invention.

[0044] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0045] 1-vertically magnetized permanent magnet, 2-horizontally magnetized permanent magnet, 3-base, 4-stator, 5-vacuum cover, 6-first winding, 7-second winding, 8-mover, 9-lower single-phase winding, 9-1-first coil, 9-2-second coil, 9-3-third coil, 10-upper single-phase winding, 10-1-fourth coil, 10-2-fifth coil, 10-3-sixth coil, 11-auxiliary wire, 11-1 first auxiliary wire, 11-2 second auxiliary wire, 11-3 third auxiliary wire, 11-4 fourth auxiliary wire. DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0047] The present invention provides a six-degree-of-freedom magnetic levitation planar motor workbench with double-layer winding coarse and fine drive, which is a double-layer winding planar motor structure with coarse and fine drive functions and is mainly used in the field of semiconductor manufacturing.

[0048] Example 1

[0049] like Figure 1 As shown, the six-degree-of-freedom magnetic levitation planar motor workbench with double-layer winding coarse and fine drive provided in this embodiment includes a stator 4 and a mover 8.

[0050] The stator 4 includes a plurality of vertically magnetized permanent magnets 1, a plurality of horizontally magnetized permanent magnets 2, and a base 3. The plurality of vertically magnetized permanent magnets 1 and the plurality of horizontally magnetized permanent magnets 2 are arranged in a Halbach manner to form a permanent magnet array structure, so that the magnetic field above the permanent magnets is enhanced and the magnetic field below is weakened. Therefore, the mover 8 is arranged above the permanent magnet array. The magnetization directions of the vertically magnetized permanent magnets 1 and the horizontally magnetized permanent magnets 2 are as follows: Figure 2 As shown by the middle arrow, the vertically magnetized permanent magnet 1 and the horizontally magnetized permanent magnet 2 are fixed in the groove of the base 3 by, for example, bonding.

[0051] The vertically magnetized permanent magnet 1 is preferably a square, and the horizontally magnetized permanent magnet 2 is preferably a rectangle. Figure 2It can be seen that the four arrows around the square vertically magnetized permanent magnet 1 all point to the vertically magnetized permanent magnet 1 magnetized along the +z axis, while the vertically magnetized permanent magnet 1 magnetized along the -z axis, away from the vertically magnetized permanent magnet 1, is magnetized along the +z axis. According to the magnetic field characteristics of the Halbach array, the +z axis direction is the magnetic field reinforcement side, that is, above the stator 4. The mover 8 is located on the reinforcement side of the air gap magnetic field. The mover 8 includes a vacuum cover 5, a first winding 6, and a second winding 7. The first winding is farther away from the permanent magnet array structure, and the second winding is closer to the permanent magnet array. The height of the first winding 6 is less than that of the second winding 7.

[0052] like Figure 3 As shown, the second winding 7 includes four groups of lower single-phase windings 9 arranged in 2 rows and 2 columns, namely four groups of first single-phase windings. Each lower single-phase winding 9 is composed of a first coil 9-1, a second coil 9-2 and a third coil 9-3, all of which are rectangular coils arranged at equal intervals. The long sides of the coils of each two adjacent groups of lower single-phase windings 9 are perpendicular to each other. Therefore, the second winding 7 consists of a total of 12 coils, and the overall layout is in a "windmill-type" shape.

[0053] The first winding 6 is located directly above the second winding 7. The first winding 6 has the same structure as the second winding 7 and only differs in height. Specifically, the first winding 6 includes four groups of upper single-phase windings 10 arranged in 2 rows and 2 columns, namely four groups of first single-phase windings. Each upper single-phase winding 10 is composed of a fourth coil 10-1, a fifth coil 10-2 and a sixth coil 10-3, all of which are rectangular coils arranged at equal intervals. The long sides of the coils of each adjacent group of upper single-phase windings 10 are perpendicular to each other. Therefore, the first winding 6 consists of a total of 12 coils, and the overall arrangement is in a "windmill-type" manner.

[0054] The rectangular coils in the first winding 6 and the rectangular coils in the second winding 7 are stacked one by one. The heights of the upper and lower coils are different, that is, the heights of the first winding 6 and the second winding 7 are different. Let the height of each coil in the first winding 6 be h1, and the height of each coil in the second winding 7 be h2. The height ratio h ration The expression is as follows:

[0055]

[0056] h ration The range of is preferably [0.2, 0.6]. When the height ratio is within this range, the coils in the upper first winding are not forced to draw large currents to generate the desired force and torque due to the low magnetic field strength, which would cause excessive heating of the coils. Furthermore, compared to the coils in the lower second winding, the coils in the upper first winding have lower high-order harmonic content in the magnetic field strength, resulting in smaller fluctuations in the generated driving force and torque, which is conducive to achieving smooth motion control.

[0057] The long sides of the rectangular coils in the first winding 6 and the second winding 7 are at an angle of 45°±1° to the right angle side of the vertically magnetized permanent magnet 1. The 45°±1° angle is designed to facilitate the decoupling of the air gap magnetic field. After rotation, the magnetic field intensity component B of the air gap magnetic field along the x-axis is x Only related to the x-axis position, the magnetic field strength component B along the y-axis y Only related to the y-axis position, and B x and B x The fundamental components are all sinusoidally distributed along the corresponding axes.

[0058] The rectangular coils in the lower single-phase winding 9 and the upper single-phase winding 10 are preferably rectangular coreless coils. The long side of the rectangular coil is preferably four times the pole pitch, and the center distance between adjacent rectangular coils is preferably 4 / 3 times the pole pitch. This helps suppress the coupling between the driving force and driving torque generated by the short side, thereby achieving decoupled calculation.

[0059] The outer contour of the mover 8 is square or approximately square. This approximately square shape means that the aspect ratio of the smallest rectangle that can accommodate the outer contour of the mover is in the range of [0.9, 1.1]. The approximately rotationally symmetrical structure is less likely to cause deflection torque, which helps reduce the directional dependence of the planar motor.

[0060] The mover 8 is disposed in the vacuum cover 5 so that the mover 8 can operate in a vacuum environment and avoids the mover coil radiating heat to the stator permanent magnet array structure and affecting the magnetic field distribution.

[0061] Example 2

[0062] The difference between this embodiment and embodiment 1 lies in the different arrangement of the rectangular coils in the first winding 6 and the second winding 7 of the mover, as well as the different relative positions of the first winding 6 and the second winding 7. The other structures and connections are the same as those in embodiment 1. The details are as follows:

[0063] like Figure 4 As shown, in this embodiment, the first winding 6 includes three sets of second single-phase windings. Each second single-phase winding comprises four rectangular coils stacked in a stepped pattern. One set of second single-phase windings is placed flat in the middle, while the other two sets of second single-phase windings are placed vertically on the upper left and lower right steps of the middle second single-phase winding, respectively, and are aligned with the middle second single-phase winding at the stepped connection. The long sides of the rectangular coils on the two side second single-phase windings are perpendicular to the long side of the rectangular coil of the middle second single-phase winding.

[0064] The second winding 7 has the same structure as the first winding 6 but different thickness. The first winding 6 rotates 90° counterclockwise around its own center to obtain the orientation of the second winding 7. The overall structure of the mover is similar to a "fishbone shape".

[0065] Example 3

[0066] The difference between this embodiment and embodiment 1 lies in the different arrangement of the rectangular coils in the first winding 6 and the second winding 7 of the mover, as well as the different relative positions of the first winding 6 and the second winding 7. The other structures and connections are the same as those in embodiment 1. The details are as follows:

[0067] like Figure 5 As shown, in this embodiment, the first winding 6 includes 7 rows, with 2 rectangular coils in each row. The short sides of adjacent rectangular coils in each row are connected. A rectangular coil in a row can be concentric with another rectangular coil after being translated along the long side direction. Adjacent rows are staggered left and right.

[0068] The second winding 7 has the same structure as the first winding 6 but different thickness. The long side of the rectangular coil in the first winding 6 and the long side of the rectangular coil in the second winding 7 are perpendicular to each other. The first winding 6 and the second winding 7 are arranged similarly in an "orthogonal" shape.

[0069] Example 4

[0070] The six-DOF magnetic levitation planar motor worktable with double-layer winding coarse and fine drive provided in this embodiment includes a stator 4 and a mover 8. The structure of the stator 4 is the same as that of embodiments 1-3.

[0071] The mover 8 is located on the strengthening side of the air gap magnetic field. The mover 8 includes a vacuum cover 5, a first winding 6 and a second winding 7. The first winding 6 is located directly above the second winding 7.

[0072] like Figure 6 As shown, in this embodiment, the first winding 6 includes 4 rows*4 columns of circular coils, and the circular coils in the first winding 6 and the second winding 7 are stacked concentrically in a one-to-one correspondence.

[0073] The first winding 6 and the second winding 7 have the same structure and only differ in height. The ratio of the height h1 of the first winding 6 to the height h2 of the second winding 7 is ration The range is the same as that of Examples 1-3.

[0074] The mover 8 is disposed in the vacuum cover 5 so that the mover 8 can operate in a vacuum environment and avoids the mover coil radiating heat to the stator permanent magnet array structure and affecting the magnetic field distribution characteristics.

[0075] In the magnetic levitation planar motor worktables with double-layer winding coarse and fine drive provided in Examples 1-4 of the present invention, the stators are composed of multiple vertically magnetized permanent magnets 1 and multiple horizontally magnetized permanent magnets 2 arranged in a Halbach pattern, forming a permanent magnet array structure. Compared to the one-dimensional arrangement used in linear motors, the magnetic field generated by the two-dimensional arrangement of the permanent magnet array structure of the present invention enables motion in both the x and y directions, thus expanding the range of motion of the planar motor.

[0076] Each mover has a double-layer winding, both located on the side of the magnetic field reinforcement. The first winding is farther away from the permanent magnet array structure, and the second winding is closer to the permanent magnet array. The height of the first winding is less than that of the second winding. In Examples 1-4, a total of four first / second winding coil topologies are provided. Among them, the "windmill-shaped" coil topology of Example 1 has the lowest directional dependence, the "fishbone-shaped" coil topology of Example 2 has the lowest power consumption, and the "concentric circular" coil topology of Example 4 has higher symmetry.

[0077] When energized, the first and second windings interact with the air gap magnetic field generated by the stator permanent magnet array, generating driving forces and torques in six directions. Because the magnetic field strength above the permanent magnet array is periodically distributed, Fourier series analysis shows that the magnetic field can be considered to be a combination of fundamental and harmonic waves.

[0078] As the height of the air gap magnetic field increases, the fundamental wave's proportion increases, while the harmonics' proportion decreases. During current decoupling, to reduce calculation time and increase system control frequency, the fundamental component of the magnetic field strength is typically used to calculate the driving force and torque, which are then used to allocate the current required to each coil. However, the presence of magnetic field harmonics causes fluctuations in the driving force and torque, impacting the system's positioning accuracy and tracking performance.

[0079] Therefore, the mover of the present invention adopts a double-layer winding arrangement. The second winding of the lower layer serves as a "macro-motion platform". In the variable speed motion stage, it provides a larger driving force and driving torque, so that the mover can move quickly to the target position. The first winding of the upper layer serves as a "micro-motion platform". In the uniform straight line stage, it provides a driving force and driving torque with smaller fluctuations. The driving force and driving torque are accurately compensated according to the feedback signal to achieve high-speed and high-precision motion control.

[0080] The mover of the present invention adopts a double-layer winding arrangement, which can reduce output fluctuations during movement, improve movement accuracy, and provide reliable technical support for ultra-precision manufacturing fields such as semiconductor processing.

[0081] The following experimental analysis is conducted to further verify the use effect of the magnetic levitation planar motor workbench with double-layer winding coarse and fine drive provided by Examples 1-4 of the present invention.

[0082] In semiconductor processing, the workbench is usually arranged as follows Figure 7 The movement is carried out along the trajectory shown. The path is mainly divided into a uniform linear motion stage and an acceleration and deceleration motion stage. The actual processing stage of the workbench is a uniform linear stage. Due to the low control accuracy of the stage, it is usually not used for processing operations.

[0083] The advantage of the planar motor of the present invention is that in the non-uniform linear stage, the larger driving force / torque generated by the second winding 7 can be used to accelerate and decelerate the movement, and in the uniform linear stage, the low ripple driving force / torque generated by the first winding 6 is used to perform uniform linear motion, which is used to reduce the system temperature rise and improve the system positioning accuracy.

[0084] At the same time, according to Maxwell's equations, the volume is V and the current density vector is A current-carrying conductor in a magnetic field of In a magnetic field of for:

[0085]

[0086] The driving torque around each axis can be calculated by the driving force and the lever arm The product of is:

[0087]

[0088] The actual driving force required during the control process and driving torque After current decoupling is performed by the host computer, the output current of each coil driver is controlled.

[0089] Magnetic field strength It varies with the position of the current-carrying conductor in the coil.

[0090] It can be seen from formula (3) that only the magnetic field strength Only with accurate calculations can we obtain the actual current density required based on the expected force and expected torque.

[0091] In order to achieve analytical calculation of the Lorentz force, the magnetic field is usually modeled using the Fourier series method.

[0092] According to the Fourier series method, the magnetic field strength by fundamental wave and harmonics of all orders Add them together, that is:

[0093]

[0094] However, in actual control, due to processor performance limitations, in order to increase the control frequency, the fundamental component of the magnetic field intensity is usually used. Instead of magnetic field strength The actual driving force generated at this time for

[0095]

[0096] Actual driving torque for:

[0097]

[0098] Actual driving force and expectation-driven There are differences, which cause thrust fluctuations.

[0099] Therefore, if the harmonic content of each order when n is greater than 1 is reduced, the theoretical Lorentz force can be and the actual Lorentz force It is closer, which can effectively reduce the driving force / torque fluctuation and improve the positioning accuracy and motion performance of the magnetic levitation planar motor.

[0100] In order to better verify the implementation effect of the present invention, auxiliary lines 11 are arranged in a direction parallel to the x-axis. Specifically, four auxiliary lines 11-1, 11-2, 11-3 and 11-4 are arranged at equal intervals of 1 mm, and the length of each is 10 times the magnetic pitch τ. The first auxiliary line 11-1 is 1 mm away from the upper surface of the permanent magnet, and the fourth auxiliary line 11-4 is 5 mm away from the upper surface of the permanent magnet. Figure 8 shown.

[0101] At this time, there is no y-direction magnetic field component on each line segment, only the magnetic field components along the x and z directions. and The components of the magnetic field in each direction are calculated and transformed by FFT, as shown in Figures 9(a), 9(b), 10(a), and 10(b). It can be seen that the amplitudes of the fundamental wave and harmonics decrease with the increase of the air gap.

[0102] In order to quantitatively analyze the proportion of magnetic field harmonics at different heights, the concept of total harmonic distortion (THD) is introduced as follows:

[0103]

[0104] The results of calculating the THD of the isotropic magnetic field on each line segment are as follows: Figure 11 As shown, as the air gap height increases from 1mm to 4mm, the auxiliary line and The THD is significantly reduced.

[0105] In order to explain more clearly how the Lorentz force is generated, Figure 12 This is a side view of the magnetic levitation planar motor. It can be seen that the upper coil and the lower coil are both located on the strengthened side of the air gap magnetic field.

[0106] The surface current density vectors on the cross sections of the first coil 9 - 1 and the fourth coil 10 - 1 are respectively and The magnitudes are equal and the directions are opposite. The surface current density vectors on the cross section of the fourth coil 10-1 are and Equal in size and opposite in direction.

[0107] According to the left-hand rule, the horizontal force along the x-axis generated by the first coil 9-1 in the magnetic field is:

[0108]

[0109] The vertical force along the z-axis is:

[0110]

[0111] The horizontal force along the x-axis generated by the fourth coil 10 - 1 in the magnetic field is:

[0112]

[0113] The vertical force along the z-axis is:

[0114]

[0115] in Conductors , where l is the equivalent length of the long sides of the first coil 9 - 1 and the fourth coil 10 - 1 .

[0116] Ignore the influence of the short side of the coil. Since the current direction of the first coil 9-1 and the fourth coil 10-1 is in the same direction as the y-axis, there is no horizontal force along the y-axis.

[0117] Combine Figure 11 It can be seen that when the planar motor workbench of the present invention is working, the coil thickness in the lower second winding 7 is relatively large, which is convenient for generating a larger driving force and driving torque in the variable speed motion stage, thereby realizing high-speed motion. At the same time, as the air gap height increases, the total harmonic distortion of the isotropic magnetic field becomes smaller and smaller, and the driving force / torque generated by the coil in the upper first winding 6 has a smaller fluctuation, which is conducive to achieving high-precision motion control goals in the uniform speed motion stage.

[0118] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A magnetic levitation planar motor workbench with a double-layer winding coarse and fine drive, the workbench comprising a stator (4) and a mover (8), characterized in that: The stator (4) comprises a base (3), and a plurality of vertically magnetized permanent magnets (1) and a plurality of horizontally magnetized permanent magnets (2) arranged in a groove of the base (3) in a Halbach arrangement manner; The mover (8) is located on the reinforcing side of the magnetic field generated by the stator (4); the mover (8) comprises a first winding (6) and a second winding (7) stacked on the first winding (6), the height of the first winding (6) being less than the height of the second winding (7); the first winding (6) and the second winding (7) each comprise a plurality of coils capable of generating driving forces in two directions when energized, so that the first winding (6) and the second winding (7) each have a six-degree-of-freedom driving force and a driving torque; the outline of the mover (8) is square or approximately square; The first winding (6) comprises four groups of first single-phase windings arranged in 2 rows and 2 columns, the first single-phase winding comprises a rectangular coils arranged in parallel with equal spacing, and the long sides of the rectangular coils of each two adjacent groups of the first single-phase windings are perpendicular to each other; The second winding (7) has the same structure as the first winding (6) and differs only in height; the rectangular coils in the first winding (6) and the rectangular coils in the second winding (7) are stacked one on top of another.

2. A magnetic levitation planar motor workbench with a double-layer winding coarse and fine drive, the workbench comprising a stator (4) and a mover (8), characterized in that: The stator (4) comprises a base (3), and a plurality of vertically magnetized permanent magnets (1) and a plurality of horizontally magnetized permanent magnets (2) arranged in a groove of the base (3) in a Halbach arrangement manner; The mover (8) is located on the reinforcing side of the magnetic field generated by the stator (4); the mover (8) comprises a first winding (6) and a second winding (7) stacked on the first winding (6), the height of the first winding (6) being less than the height of the second winding (7); the first winding (6) and the second winding (7) each comprise a plurality of coils capable of generating driving forces in two directions when energized, so that the first winding (6) and the second winding (7) each have a six-degree-of-freedom driving force and a driving torque; the outline of the mover (8) is square or approximately square; The first winding (6) includes three groups of second single-phase windings, and the second single-phase windings include b rectangular coils stacked in a stepped manner, one group of the second single-phase windings is placed flat in the middle, and the other two groups of the second single-phase windings are placed vertically on the upper left and lower right steps of the middle second single-phase winding, respectively, and are in contact with each other at the connection points of the middle second single-phase winding steps; The second winding (7) has the same structure as the first winding (6) but a different height. The orientation of the second winding (7) is obtained by rotating the first winding (6) 90° counterclockwise around its own center.

3. A magnetic levitation planar motor workbench with a double-layer winding coarse and fine drive, the workbench comprising a stator (4) and a mover (8), characterized in that: The stator (4) comprises a base (3), and a plurality of vertically magnetized permanent magnets (1) and a plurality of horizontally magnetized permanent magnets (2) arranged in a groove of the base (3) in a Halbach arrangement manner; The mover (8) is located on the reinforcing side of the magnetic field generated by the stator (4); the mover (8) comprises a first winding (6) and a second winding (7) stacked on the first winding (6), the height of the first winding (6) being less than the height of the second winding (7); the first winding (6) and the second winding (7) each comprise a plurality of coils capable of generating driving forces in two directions when energized, so that the first winding (6) and the second winding (7) each have a six-degree-of-freedom driving force and a driving torque; the outline of the mover (8) is square or approximately square; The first winding (6) comprises c rows, each row having d rectangular coils, the short sides of adjacent rectangular coils in each row being connected, and adjacent rows being staggered left and right; The second winding (7) has the same structure as the first winding (6) but different heights; the long side of the rectangular coil in the first winding (6) and the long side of the rectangular coil in the second winding (7) are perpendicular to each other.

4. A magnetic levitation planar motor workbench with a double-layer winding coarse and fine drive, the workbench comprising a stator (4) and a mover (8), characterized in that: The stator (4) comprises a base (3), and a plurality of vertically magnetized permanent magnets (1) and a plurality of horizontally magnetized permanent magnets (2) arranged in a groove of the base (3) in a Halbach arrangement manner; The mover (8) is located on the reinforcing side of the magnetic field generated by the stator (4); the mover (8) comprises a first winding (6) and a second winding (7) stacked on the first winding (6), the height of the first winding (6) being less than the height of the second winding (7); the first winding (6) and the second winding (7) each comprise a plurality of coils capable of generating driving forces in two directions when energized, so that the first winding (6) and the second winding (7) each have a six-degree-of-freedom driving force and a driving torque; the outline of the mover (8) is square or approximately square; The first winding (6) and the second winding (7) each comprise e rows*e columns of circular coils, and the circular coils in the first winding (6) and the second winding (7) are stacked in upper and lower concentric circles in a one-to-one correspondence.

5. A magnetic levitation planar motor workbench with double-layer winding coarse and fine drive according to any one of claims 1 to 4, characterized in that: The range of the height ratio between the first winding (6) and the second winding (7) is [0.2, 0.6].

6. A magnetic levitation planar motor workbench with double-layer winding coarse and fine drive according to any one of claims 1 to 3, characterized in that: The long sides of the rectangular coils in the first winding (6) and the second winding (7) are both at an angle of 45°±1° to the right-angled sides of the vertically magnetized permanent magnet (1).

7. The magnetic levitation planar motor workbench with double-layer winding coarse and fine drive according to claim 1, characterized in that: In the first single-phase winding, the long side of the rectangular coil is four times the pole pitch, and the center distance between adjacent rectangular coils is 4 / 3 times the pole pitch.

8. A magnetic levitation planar motor workbench with double-layer winding coarse and fine drive according to claim 1 or 2, characterized in that: The workbench also includes a vacuum cover, and the mover (8) is arranged inside the vacuum cover.

9. The magnetic levitation planar motor workbench with double-layer winding coarse and fine drive according to claim 1, characterized in that: The vertically magnetized permanent magnet (1) is square, and the horizontally magnetized permanent magnet (2) is rectangular.

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