Magnetic Levitation Halbach Micro Permanent Magnet Linear Motor and Motor Design Method

Abstract

The present invention discloses a magnetic levitation Halbach micro permanent magnet linear motor and a motor design method. The linear motor includes a housing, a U-shaped electromagnet, and an electromagnetic drive module; the U-shaped electromagnet is installed at the bottom of the housing, and both ends of the U-shaped electromagnet are arranged towards the electromagnetic drive module, and an electromagnet winding is wound around the middle of the U-shaped electromagnet; the electromagnetic drive module includes a primary module and a secondary module that cooperate with each other. The secondary module is fixedly installed on the top of the housing, and the primary module is arranged between the U-shaped electromagnet and the secondary module; on the side of the primary module facing the U-shaped electromagnet, there are two magnetic levitation permanent magnets with opposite magnetization directions. By forming a levitation structure between the magnetic levitation permanent magnets on the primary module and the U-shaped electromagnet in this application, the frictional resistance during the forward movement of the mover can be reduced to a certain extent, thereby increasing the thrust density and improving the mechanical performance of the micro linear motor.

Description

Technical Field

[0001] The present invention relates to a magnetic levitation Halbach micro permanent magnet linear motor and a motor design method. Background Art

[0002] In recent years, the rapid development of micro-precision machining and manufacturing has driven the progress of the high-precision manufacturing field. Among them, micro electro-mechanical systems (MEMS), as new micro sensors and micro actuators, have received extensive research attention in the field of precision micro-machining.

[0003] Currently, well-known micro linear motors have various structures such as electrostatic drive, piezoelectric drive, and electromagnetic drive. Among them, the electrostatic drive structure consists of two electrode plates as the stator and rotor, and uses the principle of variable capacitance and dielectric relaxation to generate mechanical torque; the piezoelectric drive structure consists of a stator that generates ultrasonic vibration and a rotor in contact with the stator. Using ultrasonic vibration as the power source, relying on the contact friction of the rotor to transmit the vibration of the stator, and converting the vibration into linear displacement or continuous rotational motion; the electromagnetic drive structure consists of a rotor and an energized coil, using the electromagnetic field as the medium for energy conversion, and converting electrical energy into mechanical energy through electromagnetic action.

[0004] However, the electrostatic structure has a relatively high drive voltage, and the electrode insulation is prone to failure in a humid and dusty environment. Moreover, as the size of the electrostatic actuator continues to decrease, the large electrostatic friction force reduces the output torque and shortens the service life of the actuator; the piezoelectric structure has problems such as drive energy dissipation, low drive efficiency, and insufficient load drive capacity; most design schemes of the electromagnetic structure cannot balance the two indicators of improving the thrust density and reducing the thrust ripple, and there is a large friction force when carrying a load in practical applications, and the topological structure is relatively complex, making it difficult to apply to actual production and processing, so it remains more in the laboratory research stage. Summary of the Invention

[0005] The purpose of the present invention is to provide a magnetic levitation Halbach micro permanent magnet linear motor and a motor design method to solve the problem of frictional resistance suffered by the primary module of the existing motor during forward movement.

[0006] To solve the above technical problems, the present invention provides a magnetic levitation Halbach micro permanent magnet linear motor, which includes a housing, an electromagnetic drive module, and a U-shaped electromagnet; the electromagnetic drive module and the U-shaped electromagnet are respectively installed on the top and bottom of the housing in an up-and-down opposed manner; the U-shaped electromagnet is installed at the bottom of the housing, and both ends of the U-shaped electromagnet are arranged towards the electromagnetic drive module, and an electromagnet winding is wound around the middle of the U-shaped electromagnet; the electromagnetic drive module includes a primary module and a secondary module that cooperate with each other; the secondary module is fixedly installed on the top of the housing, and the primary module is arranged between the U-shaped electromagnet and the secondary module; on the side of the primary module facing the U-shaped electromagnet, there are two magnetic levitation permanent magnets with opposite magnetization directions; the two magnetic levitation permanent magnets are respectively aligned with both ends of the U-shaped electromagnet, and the magnetization direction of the magnetic levitation permanent magnets is opposite to the magnetic field generated by both ends of the U-shaped electromagnet.

[0007] Further, the primary module includes a first silicon substrate, and a guiding permanent magnet is arranged on the side of the first silicon substrate facing the secondary module; the secondary module includes a second silicon substrate, and an A / B phase winding is arranged on the side of the second silicon substrate facing the primary module.

[0008] Further, the guiding permanent magnet includes a plurality of rectangular permanent magnet bars arranged in sequence along the first silicon substrate to form a Halbach permanent magnet array; the structures of the plurality of rectangular permanent magnet bars are the same, and the widths of the plurality of rectangular permanent magnet bars are equal to the width of the first silicon substrate, and the total length of the plurality of rectangular permanent magnet bars is equal to the length of the first silicon substrate.

[0009] Further, the A / B phase winding is engraved on the second silicon substrate.

[0010] Further, the U-shaped electromagnet is embedded in the middle of the top wall of the housing; the secondary module is fixedly installed in the middle of the bottom wall of the housing through a groove insertion structure.

[0011] In addition, the present application also provides a design method for designing the above magnetic levitation Halbach micro permanent magnet linear motor, including the following steps:

[0012] S1: Based on the Ampere molecular circulation hypothesis and Maxwell's equations, establish an analytical model of the air gap magnetic flux density in the upper and lower air gaps of the mover, and obtain the air gap magnetic flux density equation in the z-axis direction generated by the Halbach permanent magnet array:

[0013]

[0014] Among them, a is the length of the permanent magnet, b is the height of the permanent magnet, and k i represents the current line density;

[0015] S2: Establish a calculation model for the electromagnetic force of the mover based on the magnitude of the air-gap magnetic density:

[0016] (1) Repulsive force in the z-axis direction:

[0017]

[0018] (2) Thrust force in the direction of the mover's movement:

[0019]

[0020] where i A (t) and i B (t) are alternating currents with equal magnitudes and a fixed phase difference, and τ is the spacing between the two-phase windings.

[0021] The beneficial effects of the present invention are as follows: By setting magnetically suspended permanent magnets with opposite magnetization directions on the primary module and setting a U-shaped electromagnet for providing repulsive force to form a suspension structure for the magnetically suspended permanent magnets, the frictional resistance during the forward movement of the mover can be reduced to a certain extent, and thus the thrust density can be increased. Description of the Drawings

[0022] The drawings described herein are used to provide a further understanding of the present application and form a part of the present application. The same reference numerals are used to represent the same or similar parts in these drawings. The schematic embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings:

[0023] Figure 1 Schematic diagram of the relative positions of the housing, electromagnetic drive module, and U-shaped electromagnet in an embodiment of the present invention;

[0024] Figure 2 Cross-sectional view in the horizontal direction in an embodiment of the present invention;

[0025] Figure 3 Longitudinal view in an embodiment of the present invention;

[0026] Figure 4 Schematic diagram of the structure of the A / B-phase windings and the guiding permanent magnet in an embodiment of the present invention;

[0027] Figure 5 In an embodiment of the present invention Figure 2 Enlarged view of the partial A;

[0028] Figure 6 Waveform diagram of the z-axis component of the guiding air-gap magnetic density in an embodiment of the present invention;

[0029] Figure 7 Waveform diagram of the force on the primary module in the z-axis direction in an embodiment of the present invention.

[0030] Wherein: 1. Outer shell; 2. U-shaped electromagnet; 21. Two end parts of the U-shaped electromagnet; 3. Electromagnet winding; 4. Magnetically suspended permanent magnet; 5. First silicon substrate; 6. Guide permanent magnet; 7. Second silicon substrate; 71. Groove; 8. A / B-phase winding. Specific embodiments

[0031] As Figures 1-3 The magnetic levitation Halbach micro permanent magnet linear motor shown includes a housing, an electromagnetic drive module, and a U-shaped electromagnet 2; the electromagnetic drive module and the U-shaped electromagnet 2 are respectively installed on the top and bottom of the housing in an up-and-down opposed manner; the U-shaped electromagnet 2 is installed at the bottom of the housing, and the two ends of the U-shaped electromagnet 2 face the electromagnetic drive module, and an electromagnet winding 3 is wound around the middle of the U-shaped electromagnet 2; the electromagnetic drive module includes a primary module and a secondary module that cooperate with each other; the secondary module is fixedly installed on the top of the housing, and the primary module is arranged between the U-shaped electromagnet 2 and the secondary module; on the side of the primary module facing the U-shaped electromagnet 2, there are two magnetically suspended permanent magnets 4 with opposite magnetization directions; the two magnetically suspended permanent magnets 4 are respectively aligned with the two ends of the U-shaped electromagnet 2, and the magnetization direction of the magnetically suspended permanent magnet 4 is opposite to the magnetic field generated by the two end parts 21 of the U-shaped electromagnet 2. In this application, by arranging magnetically suspended permanent magnets 4 with opposite magnetization directions on the primary module and arranging a U-shaped electromagnet 2 for providing a repulsive force to form a suspension structure for the magnetically suspended permanent magnets 4, the frictional resistance during the forward movement of the mover can be reduced to a certain extent.

[0032] According to an embodiment of the present application, the primary module includes a first silicon substrate 5, and a guide permanent magnet is provided on the side of the first silicon substrate 5 facing the secondary module; the secondary module includes a second silicon substrate 7, and an A / B-phase winding 8 is provided on the side of the second silicon substrate 7 facing the primary module. By adopting a two-phase winding, compared with a three-phase winding motor, the control is simpler, the wire arrangement is clearer, and the structure is simple, which is beneficial to the installation of the motor. According to the principle that like currents repel each other, the winding spacing and winding wire diameter can be determined by Maxwell finite element simulation analysis to obtain the optimal structural parameter values, and at the same time, its size should also be greater than the limit requirements of production and processing.

[0033] According to an embodiment of the present application, the guiding permanent magnet includes a number of rectangular permanent magnet bars arranged in sequence along the first silicon substrate 5 to form a Halbach permanent magnet array; by magnetizing in a multi-polarization manner, the rectangular permanent magnet bars evenly arranged on the silicon substrate present four magnetization directions of vertically upward, horizontally leftward, vertically downward, and horizontally rightward in the motor operation direction; the width of the rectangular permanent magnet bar is equal to the width of the first silicon substrate 5, and the total length of the number of rectangular permanent magnet bars is equal to the length of the first silicon substrate 5. The rectangular permanent magnet bar can adopt a neodymium iron boron magnet. By using the Halbach permanent magnet array continuous magnetization array as the mover structure, the magnetic field generated by the permanent magnet mainly gathers in the air gap, which improves the air gap magnetic density to a certain extent and is beneficial to increasing the thrust density.

[0034] According to an embodiment of the present application, the A / B phase winding 8 is engraved on the second silicon substrate 7. By engraving the winding on the second silicon substrate 7, the occupied space of the winding can be reduced, which is beneficial to installation.

[0035] According to an embodiment of the present application, the U-shaped electromagnet 2 is embedded in the middle of the top wall of the housing; the secondary module is fixedly installed in the middle of the bottom wall of the housing through a groove insertion structure. As Figure 5 shown, by respectively arranging grooves 71 matching the bottom wall of the housing on both sides of the second silicon substrate 7, during installation, the bottom wall of the second silicon housing is inserted into the grooves on both sides of the substrate to complete the installation. This connection structure is simple to install, does not require additional fasteners for installation, and has good installation stability.

[0036] The working mode of this magnetic levitation Halbach micro permanent magnet linear motor is as follows:

[0037] Step 1: Pass direct current into the copper winding led out from the magnetic levitation housing 1 structure. In the case of the primary module with a size of 2mm×2mm×0.1mm, the direct current is set to 0.1A - 0.5A. Different direct current magnitudes will cause the air gap of the primary module to change accordingly. This state is maintained for about 5s to ensure the stable levitation of the primary module;

[0038] Step 2: Pass alternating current with equal amplitude, the same frequency, and different phases into the two-phase windings of the secondary module. In this example, the A phase is set to sin(20π·t), and the B phase is set to sin(20π·t + 0.1745). Increasing the amplitude of the alternating current can increase the magnitude of the thrust.

[0039] Through simulation experiment analysis, the periodic distribution of the z-axis component of the air gap magnetic density is in the range of -0.8 to 0.8mT (as Figure 6 shown), and this component is the main source of the mover thrust; through transient field analysis, the thrust is in the form of a sine wave (as Figure 7As shown, the maximum can reach 16 mN in this example, effectively increasing the mover acceleration and better meeting the requirements for speed and precision in micro-motors.

[0040] In addition, this application also discloses a design method for the above-mentioned magnetic levitation Halbach micro permanent magnet linear motor, including the following steps:

[0041] S1: Based on the Ampere molecular circulation hypothesis and Maxwell's equations, establish an analytical model of the flux density in the upper and lower air gaps of the mover, expressed as:

[0042] (1) Levitation air gap flux density

[0043]

[0044] Among them, N is the number of turns of copper winding, δ is the air gap distance, a is the length of the permanent magnet, b is the height of the permanent magnet, and l is the distance between two permanent magnet bars.

[0045] (2) Guidance air gap flux density

[0046] According to the molecular circulation hypothesis, it is considered that the magnetic field in the external space of the permanent magnet is excited by the closed current loop on the surface of the permanent magnet.

[0047] In a three-dimensional plane, a single z-axis magnetized permanent magnet generates a magnetic field:

[0048]

[0049] A single y-axis (mover movement direction) magnetized permanent magnet generates a magnetic field:

[0050]

[0051] Therefore, the z-axis direction air gap flux density generated by the Halbach permanent magnet array is

[0052]

[0053] Among them, a is the length of the permanent magnet, b is the height of the permanent magnet, and k1, k2 represent the current line density.

[0054] S2: Establish a mover electromagnetic force calculation model according to the air gap magnetic density magnitude:

[0055] (1) Repulsive force in the z-axis direction:

[0056]

[0057] (2) Thrust force in the mover movement direction:

[0058]

[0059] Among them, iA (t) and i B (t) is an alternating current with equal magnitude and a fixed phase difference, and τ is the spacing between the two-phase windings.

[0060] Through simulation experiment analysis, the obtained air-gap flux density and the magnitude of the moving force have a good fitting degree with the above mathematical model.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A magnetic levitation Halbach micro permanent magnet linear motor, characterized in that, It includes a housing, an electromagnetic drive module, and a U-shaped electromagnet; the electromagnetic drive module and the U-shaped electromagnet are respectively installed on the top and bottom of the housing in an up-and-down opposed manner; The U-shaped electromagnet is installed at the bottom of the housing, and the two ends of the U-shaped electromagnet are arranged towards the electromagnetic drive module, and an electromagnet winding is wound around the middle of the U-shaped electromagnet; The electromagnetic drive module includes a primary module and a secondary module that cooperate with each other; the secondary module is fixedly installed on the top of the housing, and the primary module is arranged between the U-shaped electromagnet and the secondary module; on the side of the primary module facing the U-shaped electromagnet, there are two magnetically suspended permanent magnets with opposite magnetization directions; the two magnetically suspended permanent magnets are respectively aligned with the two ends of the U-shaped electromagnet, and the magnetization direction of the magnetically suspended permanent magnets is opposite to the magnetic field generated by the two end parts of the U-shaped electromagnet; The working mode of this magnetic levitation Halbach micro permanent magnet linear motor is as follows: Step 1: Pass a direct current into the primary module. When the magnitude of the direct current is different, the air gap of the primary module will change accordingly. This state is maintained for about T time to ensure the stable suspension of the primary module; Step 2: Pass an alternating current with equal amplitude, the same frequency, and different phases into the two-phase windings of the secondary module.

2. The magnetic levitation Halbach micro permanent magnet linear motor according to claim 1, wherein The primary module includes a first silicon substrate, and a guiding permanent magnet is arranged on the side of the first silicon substrate facing the secondary module; the secondary module includes a second silicon substrate, and an A / B-phase winding is arranged on the side of the second silicon substrate facing the primary module.

3. The magnetic levitation Halbach micro permanent magnet linear motor according to claim 2, characterized in that, The guiding permanent magnet includes a number of rectangular permanent magnet bars arranged in sequence along the first silicon substrate to form a Halbach permanent magnet array; the structures of the number of rectangular permanent magnet bars are the same, and the widths of the number of rectangular permanent magnet bars are equal to the width of the first silicon substrate, and the total length of the number of rectangular permanent magnet bars is equal to the length of the first silicon substrate.

4. The magnetic levitation Halbach micro permanent magnet linear motor according to claim 2, wherein, The A / B-phase winding is engraved on the second silicon substrate.

5. The magnetic levitation Halbach micro permanent magnet linear motor according to claim 1, characterized in that, The U-shaped electromagnet is embedded in the middle of the top wall of the housing; the secondary module is fixedly installed in the middle of the bottom wall of the housing through a groove insertion structure.

6. A design method of the magnetic levitation Halbach micro permanent magnet linear motor according to claim 1, characterized in that, It includes the following steps: S1: Based on the Ampere molecular circulation hypothesis and Maxwell's equations, establish an analytical model of the air gap magnetic flux density of the mover up and down, and obtain the air gap magnetic flux density equation in the z-axis direction generated by the Halbach permanent magnet array: where a is the length of the permanent magnet, b is the height of the permanent magnet, and k i represents the current linear density; S2: Establish a calculation model of the electromagnetic force of the mover according to the magnitude of the air gap magnetic density: (1) Repulsive force in the z-axis direction: (2) Thrust in the moving direction of the mover: where i A (t) and i B (t) are alternating currents with equal magnitudes and a fixed phase difference, and τ is the spacing between the two-phase windings.

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