A linear-rotational two-degree-of-freedom motion wave generator

Abstract

The present invention discloses a linear-rotational two-degree-of-freedom wave generator, comprising a mover, a rotor and a stator coaxially nested from the inside to the outside, with gaps left between the mover and the rotor, and between the rotor and the stator, the mover comprising a cylindrical iron core and a mover spiral permanent magnet attached to the outer wall of the cylindrical iron core; the rotor comprising a cylindrical back iron, on the inner wall of which a rotor spiral permanent magnet is attached, a plurality of racks uniformly spaced along the circumference are arranged on the outer wall, a starting winding is wound around the tooth root of each rack, and each starting winding is used to generate a radially inward magnetic field to suppress the radial force between the mover and the rotor and accelerate the starting of the motor; the stator comprising a plurality of U-shaped iron cores uniformly spaced along the circumference, a stator permanent magnet is arranged between each two adjacent U-shaped iron cores, each stator permanent magnet and the side teeth of the two adjacent U-shaped iron cores constitute a stator salient pole tooth, and a stator winding is arranged on each stator salient pole tooth.

Description

Technical Field

[0001] The invention relates to the technical field of automatic control, in particular to a linear-rotational two-degree-of-freedom motion wave generator. Background Art

[0002] As the energy crisis becomes increasingly severe, sustainable green renewable energy is becoming increasingly important. Compared to wind and solar energy, wave energy, as a form of ocean energy, offers high energy density and predictability, and holds great promise for future applications.

[0003] Direct-drive wave generators have the characteristics of simple structure and are easy to manufacture. They eliminate the intermediate mechanical energy conversion link and directly connect the generator to the float of the point absorption wave power generation system, converting the linear mechanical energy of the float into the required electrical energy. They have the advantages of high efficiency and strong stability. However, direct-drive wave generators have low speed and large size, resulting in low power density. To address this problem, linear speed-increasing wave generators based on the principle of magnetic field modulation have been proposed. On the basis of direct-drive motors, a magnetic modulation structure is added to increase speed and power. However, linear speed-increasing wave generators require a large linear stroke to meet the movement of the rotor, and therefore have disadvantages such as large size and high manufacturing cost. At the same time, the structure is highly complex and the heat dissipation is poor, which may cause irreversible demagnetization of the permanent magnets and reduce the reliability of the motor.

[0004] IEEE Transactions on Magnetics, 51(11):8113604, 2015 (A Novel Magnetic-Geared Tubular Linear Machine With Halbach Permanent-Magnet Arrays for Tidal Energy Conversion) proposes a highly integrated tubular linear permanent magnet motor based on the principle of magnetic field modulation. The motor consists of a low-speed rotor, a high-speed rotor, and a magnetically modulated stator with wound windings. It features a compact structure and high space utilization. However, the stator is located between the two rotors, resulting in low structural reliability, low air gap flux density, and poor output power quality.

[0005] IEEE Transactions on Magnetics, 52(7):8202404, 2016 (Developments of an Efficient Analytical Scheme for Optimal Composition Designs of TubularLinear Magnetic-Geared Machines) analyzes and optimizes a tubular linear parallel magnetic gear motor. This motor consists of four layers: a stationary permanent magnet layer, a low-speed magnetic modulation layer, a high-speed permanent magnet layer, and a stator winding layer. The low-speed magnetic modulation layer is connected to a wave extractor. Through the magnetic modulation principle, it drives the high-speed permanent magnet layer to move. At the same time, the high-speed permanent magnet layer serves as the motor excitation layer to generate electricity. This parallel motor has many layers, a high structural complexity, and high manufacturing and installation costs.

[0006] Chinese patent CN112532010A proposes a direct-drive permanent magnet linear generator for wave power generation. This motor features an internal stator structure, while a mover, comprised of a Halbach permanent magnet array, is fixed to the inner wall of a buoy, acting as a wave extractor. The mover reciprocates with the buoy, simplifying the wave power generation system. Similar to direct-drive wave generators, this motor's power and thrust density remain relatively low. Furthermore, this structure increases the weight of the buoy, undesirably impacting wave extraction.

[0007] Chinese patent CN105811738A proposes a direct-drive, all-superconducting primary-excited linear generator for wave power generation. This generator utilizes a superconducting excitation winding to increase the air gap flux density and can adjust the magnetic field by varying the winding current, resulting in a high power factor. However, the need for a complex cooling system significantly increases the complexity of the motor, reduces its reliability, and incurs high manufacturing and maintenance costs. Summary of the Invention

[0008] The present invention provides a linear-rotational two-degree-of-freedom wave generator. This generator utilizes the principle of spiral magnetic field coupling to convert low-speed linear motion into high-speed rotational motion, addressing the issues of low thrust density and power density. The simple structure of the salient-pole reluctance rotor reduces overall structural complexity, effectively improving structural reliability. The excitation permanent magnets in the power conversion process are located on the stator side, addressing the issue of poor motor cooling. Furthermore, a starting winding is used to suppress the radial force generated by the spiral magnetic field coupling, improving the motor's starting performance.

[0009] The present invention can be achieved through the following technical solutions:

[0010] A linear-rotational two-degree-of-freedom wave generator comprises a mover, a rotor and a stator coaxially nested from the inside to the outside, with gaps left between the mover and the rotor, and between the rotor and the stator.

[0011] The mover includes a cylindrical iron core and a mover spiral permanent magnet attached to the outer wall of the cylindrical iron core, and the mover spiral permanent magnet is used to generate a mover spiral magnetic field;

[0012] The rotor includes a cylindrical back iron, on the inner wall of which a rotor spiral permanent magnet is mounted, and on the outer wall of which a plurality of racks are evenly spaced along the circumference. A starting winding is wound around the tooth root of each rack. The rotor spiral permanent magnet is used to generate a rotor spiral magnetic field, and each starting winding is used to generate a radially inward magnetic field to suppress the radial force between the mover and the rotor and accelerate the starting of the motor.

[0013] The stator includes a plurality of U-shaped iron cores arranged at even intervals along the circumference, and a stator permanent magnet is arranged between each two adjacent U-shaped iron cores for generating an excitation magnetic field. Each stator permanent magnet and the side teeth of the two adjacent U-shaped iron cores constitute a stator salient pole tooth, and each stator salient pole tooth is provided with a stator winding for generating an induced electromotive force.

[0014] Furthermore, the rack includes a triangular tooth tip and a square tooth root, and a slot structure is formed between adjacent racks. The positions of the starting windings wound on the square tooth roots are parallel to each other, and each starting winding is connected to direct current during startup.

[0015] Furthermore, the rotor spiral permanent magnets and the mover spiral permanent magnets both adopt a segmented structure and are magnetized alternately in the axial direction and radial direction.

[0016] Furthermore, the rotor spiral permanent magnets and the mover spiral permanent magnets both adopt an axial NS pole alternating radial magnetization array, an axial NS pole alternating axial magnetization permanent magnet and iron core mixed array, or a Halbach permanent magnet array.

[0017] Furthermore, the axial length of the rack is less than or equal to the axial length of the cylindrical back iron.

[0018] Furthermore, the columnar iron core includes a supporting steel core and a mover iron core sleeved on the outer wall of the supporting steel core.

[0019] Furthermore, the two side teeth of the U-shaped iron core, the middle slot, the inner arc angle of the stator permanent magnet, and the outer arc angle of the slots between adjacent racks are the same.

[0020] The beneficial technical effects of the present invention are:

[0021] 1. Due to the application of the spiral magnetic field coupling principle, the speed is increased, so that the linear-rotational two-degree-of-freedom wave generator of the present invention has high power density and thrust density.

[0022] 2. Since the rotor rack and stator have very good symmetry, high-order harmonics can be effectively suppressed, so that the generator has high-quality output voltage.

[0023] 3. Since the generator is provided with a starting winding, direct current is passed through during startup to generate a radially inward magnetic field to suppress the radial force of the spiral magnetic field, thereby having better starting performance.

[0024] 4. Because the excitation permanent magnets that perform electrical energy conversion are located on the stator side, the generator has the advantage of excellent cooling conditions, eliminating the problem of irreversible demagnetization of the permanent magnets that can occur due to poor heat dissipation. Furthermore, because the stator's armature reaction flux and the magnetization direction of the permanent magnets are orthogonal, their mutual influence is minimal, resulting in a strong resistance to demagnetization. Furthermore, the concentrated windings have small end portions, resulting in a low end effect.

[0025] 5. Since the rotor rack is a salient pole reluctance structure with a simple structure, the complexity of the generator is reduced and the overall structural reliability is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0027] Figure 2 It is a radial cross-sectional schematic diagram of the overall structure of the present invention;

[0028] Figure 3 It is a schematic diagram of an axial cross-sectional view of the mover structure of the present invention;

[0029] Figure 4 This is a schematic axial cross-sectional view of the rotor structure of the present invention;

[0030] Figure 5 Schematic diagram of the induced electromotive force change curve of the present invention;

[0031] Among them, 1-motor, 11-columnar iron core, 111-support steel core, 112-motor iron core, 12-motor spiral permanent magnet, 2-rotor, 21-cylindrical back iron, 22-rotor spiral permanent magnet, 23-rack, 24-starting winding, 25-slot structure, 3-stator, 31-U-shaped iron core, 32-stator permanent magnet, 33-stator winding. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] See attached Figure 1 The present invention discloses a linear-rotational two-degree-of-freedom wave generator, comprising a mover 1, a rotor 2, and a stator 3 coaxially nested from the inside out. Gaps are left between the mover 1 and the rotor 2, and between the rotor 2 and the stator 3, respectively denoted as gaps 4 and 5, as follows:

[0034] like Figure 3 As shown, the mover 1 includes a cylindrical iron core 11 and a mover spiral permanent magnet 12 attached to the outer wall of the cylindrical iron core 11, and the mover spiral permanent magnet 12 is used to generate a mover spiral magnetic field; in order to enhance the supporting strength of the cylindrical iron core 11, the cylindrical iron core 11 includes a supporting steel core 111 and a mover iron core 112 sleeved on the outer wall of the supporting steel core 111, and the mover iron core 112 adopts a cylindrical structure and can be seamlessly sleeved on the outside of the supporting steel core 111. The mover spiral permanent magnet 12 is attached to the outside of the mover iron core 112. The supporting steel core 111 is made of high-strength steel and plays a role in supporting the mover structure to prevent it from deformation and affecting the performance of the generator. The mover iron core 112 is made of soft magnetic material and is used for conducting the magnetic circuit.

[0035] like Figure 2 and 4 As shown, the rotor 2 includes a cylindrical back iron 21, on the inner wall of which a rotor spiral permanent magnet 22 is mounted, and on the outer wall thereof a plurality of racks 23 are evenly spaced along the circumference. A starting winding 24 is wound around the tooth root of each rack 23. The mover spiral permanent magnet 22 is used to generate a rotor spiral magnetic field, and each starting winding 24 is used to generate a radially inward magnetic field to suppress the radial force between the mover 1 and the rotor 2 and accelerate the starting of the motor.

[0036] The rotor spiral permanent magnets 22 and the mover spiral permanent magnets 12 both adopt a segmented structure and are magnetized in alternating radial directions along the axial direction. Alternatively, an array with alternating radial magnetization along the axial direction with N-spurious poles, a mixed array of axially alternating axial magnetization permanent magnets and iron cores, or a Halbach permanent magnet array can be used. Alternatively, a spiral coil wound with spiral grooves can be used to replace permanent magnets to generate a spiral magnetic field. For example, a spiral permanent magnet can be wound with two spirals, one spiral consisting of multiple segments of N-pole arc-shaped permanent magnets and the other spiral consisting of multiple segments of S-pole arc-shaped permanent magnets, thereby generating a spiral magnetic field. In this way, the spiral magnetic fields generated by the rotor spiral permanent magnets 22 and the mover spiral permanent magnets 12 are coupled to each other, thereby converting the linear motion of the mover 1 into the rotational motion of the rotor 2. Furthermore, the spiral permanent magnets on the mover 1 and rotor 2 have the same axial width.

[0037] The rack 23 includes a trapezoidal tooth tip and a square tooth root, and a slot structure 25 is formed between adjacent racks to facilitate the installation of the starting winding 24. The surface of the trapezoidal tooth tip adopts an arc structure to avoid uneven magnetic field strength. The positions of the starting winding wound on the square tooth root are parallel to each other, which facilitates the winding of the starting winding 24 and can reduce the impact of the slot between the two racks 23 on the conduction of the electric energy conversion magnetic circuit.

[0038] In addition, the axial length of the rack 23 is equal to or less than the axial length of the cylindrical back iron 21. This facilitates adjustment of the number of helical permanent magnets installed on the rotor 2, thereby adjusting the torque obtained from the helical magnetic field coupling. The portion of the cylindrical back iron 21 that is longer than the rack 23 can be made by laminating annular silicon steel sheets and then connecting them to the cylindrical back iron 21 using welding technology, or by extending the laminated thickness of the silicon steel sheets of the rack 23 and then cutting off the excess rack at both ends using cutting technology.

[0039] like Figure 1 and 3 As shown, the stator 3 includes multiple U-shaped cores 31 evenly spaced along the circumference. A stator permanent magnet 32 ​​is positioned between each pair of adjacent U-shaped cores 31. These stator permanent magnets 32 are used to generate an excitation magnetic field. Each stator permanent magnet 32 ​​and the side teeth of two adjacent U-shaped cores 31 form a stator salient pole tooth. Each stator salient pole tooth is provided with a stator winding 33 for generating an induced electromotive force. Because all stator permanent magnets 32 are evenly spaced along the circumference and are tangentially magnetized, and the stator winding 33 is an integrated winding, the armature reaction magnetic field generated by the stator winding current is radial. The two are perpendicular to each other, minimizing mutual influence and providing strong anti-demagnetization capability.

[0040] In this way, when the wave generator of the present invention is working, it is connected to the float of the point absorption wave power generation system through the mover 1, so that the wave motion is converted into the low-speed linear motion of the mover 1 along the axial direction through the motion of the float. The mover spiral magnetic field generated by the mover spiral permanent magnet 12 and the rotor spiral magnetic field of the rotor spiral permanent magnet 22 are coupled with each other in the air gap 4 to generate torque, driving the rotor 2 to rotate, thereby realizing the conversion of the low-speed linear motion of the mover 1 to the high-speed rotational motion of the rotor 2. At the same time, according to the principle of minimum magnetic resistance, the magnetic lines of force are emitted from the N pole of the stator permanent magnet 32, pass through the side of the U-shaped iron core 31, and then pass through the air gap 5 to flow to the rack, and finally pass through the cylindrical back iron 21, other racks 23, the air gap 5 and the side teeth of the other U-shaped iron core 31 to return to the S pole of the stator permanent magnet 32, forming a closed loop. When the rotor 2 rotates, the side tooth magnetic flux of the U-shaped iron core 31 changes. Since the stator winding 33 is wound around the side teeth of the U-shaped iron core 31, the magnetic flux of the stator winding 33 also changes, thereby generating an induced electromotive force and realizing the conversion of rotational mechanical energy into electrical energy.

[0041] Considering that at the moment of startup, a relatively large radial force will be generated between the two coupled spiral magnetic fields, seriously hindering the rotation of rotor 2, we have set a starting winding 24 on the rack 23 of rotor 2. During startup, a direct current is passed through starting winding 24, generating a high-intensity magnetic field directed radially inward, temporarily suppressing the magnetic field of the radially outward magnetized spiral permanent magnet. At the same time, utilizing the saturation effect of the permanent magnet, the magnetic field of the radially inward magnetized spiral permanent magnet is only slightly increased, effectively attenuating the radial force between mover 1 and rotor 2. The magnetic field coupling is in an unstable state, making motor startup easier and accelerating the motor startup. After the motor is started, the current is disconnected.

[0042] In order to suppress the generated voltage harmonics, the inner arc angles of the two side teeth, the middle slot and the stator permanent magnet 32 ​​of the U-shaped core 31 and the outer arc angles of the slots between adjacent racks 23 are the same, that is, θ1=θ2=θ3=θ4=θ5=360 / n / 4, where n is the number of U-shaped cores 31, as shown in FIG. Figure 2 As shown, the inner arc angles of the two side teeth of the U-shaped core 31 are θ1 and θ3 respectively, the inner arc angle of the middle slot is θ2, the inner arc angle of the stator permanent magnet 32 ​​is θ4, and the outer arc angle of the rack is θ5, which can effectively suppress high-order harmonics and make the generator have high-quality output voltage, as shown in FIG. Figure 5 As shown in the figure, the induced electromotive force of the generator has a very high sinusoidality and low harmonic content.

[0043] In addition, different ratios of the number of U-shaped cores in the stator and the number of racks in the rotor as well as different numbers of generator phases can be adopted according to requirements.

[0044] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to these embodiments without departing from the principles and essence of the present invention. Therefore, the scope of protection of the present invention is limited by the appended claims.

Claims

1. A linear-rotational two-degree-of-freedom wave generator, characterized by: It includes a mover, a rotor and a stator coaxially nested from the inside to the outside, with gaps left between the mover and the rotor, and between the rotor and the stator; The mover includes a cylindrical iron core and a mover spiral permanent magnet attached to the outer wall of the cylindrical iron core, and the mover spiral permanent magnet is used to generate a mover spiral magnetic field; The rotor includes a cylindrical back iron, on the inner wall of which a rotor spiral permanent magnet is mounted, and on the outer wall of which a plurality of racks are evenly spaced along the circumference, and a starting winding is wound around the tooth root of each rack. The rotor spiral permanent magnet is used to generate a rotor spiral magnetic field, and each starting winding is used to generate a radially inward magnetic field to suppress the radial force between the mover and the rotor and accelerate the starting of the motor; The stator includes a plurality of U-shaped iron cores arranged at uniform intervals along the circumference, a stator permanent magnet is arranged between each two adjacent U-shaped iron cores for generating an excitation magnetic field, each stator permanent magnet and the side teeth of the two adjacent U-shaped iron cores constitute a stator salient pole tooth, and each stator salient pole tooth is provided with a stator winding for generating an induced electromotive force; The rack includes a trapezoidal tooth tip and a square tooth root, and a slot structure is formed between adjacent racks. The positions of the starting windings wound on the square tooth roots are parallel to each other, and each starting winding is connected to direct current during startup.

2. The linear-rotational two-degree-of-freedom wave generator according to claim 1, characterized in that: The rotor spiral permanent magnet and the mover spiral permanent magnet both adopt a segmented structure and are magnetized alternately in the axial direction and radial direction.

3. The linear-rotational two-degree-of-freedom wave generator according to claim 2, characterized in that: The rotor spiral permanent magnet and the mover spiral permanent magnet both adopt a Halbach permanent magnet array, an axial NS pole alternating radial magnetization array, or an axial NS pole alternating axial magnetization permanent magnet and iron core mixed array.

4. The linear-rotational two-degree-of-freedom wave generator according to claim 1, characterized in that: The axial length of the rack is equal to or less than the axial length of the cylindrical back iron.

5. The linear-rotational two-degree-of-freedom wave generator according to claim 1, characterized in that: The columnar iron core comprises a supporting steel core and a mover iron core sleeved on the outer wall of the supporting steel core.

6. The linear-rotational two-degree-of-freedom wave generator according to claim 1, characterized in that: The two side teeth of the U-shaped iron core, the middle slot, the inner arc angle of the stator permanent magnet and the outer arc angle of the slots between adjacent racks are the same.

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