Halbach array-based adjustable magnetic permanent magnet motor rotor structure

Abstract

The application discloses a Halbach array-based adjustable magnetic permanent magnet motor rotor structure which is composed of a sheath, a permanent magnet array, an excitation winding and a rotor iron core; the permanent magnet array is formed by alternately arranging multiple alnico permanent magnets, the magnetization direction of the alnico permanent magnets is radial or tangential, and the alnico permanent magnets with the two magnetization directions are alternately arranged to form a Halbach array structure. A rotor slot is formed in the outer edge of the rotor iron core at the contact surface between the alnico permanent magnet with the tangential magnetization and the rotor iron core, so as to facilitate the arrangement of the excitation winding; a ring-shaped sheath is installed at the outer edge of the permanent magnet and is used for fixing the permanent magnet and the excitation winding, and the space between the ring-shaped sheath and the permanent magnet and the rotor slot can be used for arranging the excitation winding. The radial excitation winding can be wound on the permanent magnet with the radial magnetization, and the tangential excitation winding can be wound on the permanent magnet with the tangential magnetization. The magnetization degree of the alnico permanent magnet is changed by adjusting the size and direction of the excitation current, the size of the air gap magnetic field is controlled, and the output torque control is realized.

Description

Technical Field

[0001] This invention relates to an adjustable permanent magnet motor rotor structure based on a Halbach array, belonging to the field of hybrid excitation motor technology. Background Technology

[0002] Rare earth materials offer significant advantages as permanent magnets in electric motors: high efficiency, excellent properties, small size, and light weight—advantages unmatched by other permanent magnet materials. However, rare earths are non-renewable resources, belonging to national strategic resources, resulting in high usage costs. Furthermore, the non-adjustable magnetic field generated by permanent magnets necessitates the use of field weakening control methods at higher motor speeds. For commonly used surface-mount structures, the high strength of the permanent magnet field leads to poor field weakening effects. While built-in permanent magnet structures can achieve better field weakening, magnetic leakage in the design negatively impacts the torque density under constant torque mode.

[0003] Adjustable permanent magnet motors are formed by simultaneously installing two magnetic sources: permanent magnets and electrically excited windings. Existing adjustable permanent magnet motors are generally designed using various approaches. The permanent magnets and electrically excited windings can be mounted on the rotor or arranged on the stator. The basic principle of achieving adjustable magnetic field can be summarized as follows: the permanent magnet magnetic field generated by the permanent magnet and the electrically excited magnetic field generated by the current flowing through the electrically excited winding are vector-superimposed with the magnetic field generated by the permanent magnet in the air gap. By adjusting the current flowing through the electrically excited winding, the electrically excited magnetic field can be controlled, thereby controlling the magnitude of the total magnetic field in the air gap. However, the magnetic field strength of the permanent magnet is relatively large, often constituting the main component of the air gap magnetic field, and the ability of the electrically excited magnetic field to affect the total air gap magnetic field is limited. To increase the influence of the electrically excited magnetic field, the volume of the permanent magnet can be reduced, thus decreasing the magnitude of its output magnetic field. However, this would significantly reduce the power density of the motor. Therefore, a new motor rotor structure needs to be designed to improve motor performance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a rotor structure of an adjustable permanent magnet motor based on a Halbach array, wherein the magnetic field generated by the AlNiCo permanent magnet is controlled by the magnitude of the excitation current to achieve the adjustment of the air gap magnetic field.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A rotor structure for an adjustable permanent magnet motor based on a Halbach array includes a non-magnetic annular sleeve, tangential permanent magnets, radial permanent magnets, a tangential excitation winding, a rotor core, and a shaft. The rotor core is sleeved on the shaft. Tangential and radial permanent magnets are alternately arranged to form a Halbach array annular structure. Both tangential and radial permanent magnets are arranged on the outer edge of the rotor core. The outer diameters of the tangential and radial permanent magnets are the same, and the magnetization directions of two adjacent tangential permanent magnets are opposite, as are the magnetization directions of two adjacent radial permanent magnets. The tangential excitation winding is wound around the tangential permanent magnets and connected in series. The annular sleeve is installed on the outside of the Halbach array annular structure to fix the tangential permanent magnets, radial permanent magnets, and tangential excitation winding.

[0007] As a preferred embodiment of the present invention, the outer edge of the rotor core is provided with rotor slots, and the gap between the non-magnetic annular sheath and the Halbach array annular structure is provided with excitation winding slots. The tangential excitation winding is wound on the tangential permanent magnet through the rotor slots and the excitation winding slots. The tangential permanent magnet is made of AlNiCo permanent magnet, and the radial permanent magnet is made of AlNiCo permanent magnet, ferrite or rare earth permanent magnet.

[0008] A rotor structure for an adjustable permanent magnet motor based on a Halbach array includes a non-magnetic annular sleeve, tangential permanent magnets, radial permanent magnets, tangential excitation windings, radial excitation windings, a rotor core, and a shaft. The rotor core is fitted onto the shaft. Tangential and radial permanent magnets are alternately arranged to form a Halbach array annular structure. Both tangential and radial permanent magnets are arranged on the outer edge of the rotor core. The outer diameter of the radial permanent magnets is larger than that of the tangential permanent magnets, and the magnetization directions of two adjacent tangential permanent magnets and two adjacent radial permanent magnets are opposite. The tangential excitation windings are wound around the tangential permanent magnets, and the radial excitation windings are wound around the radial permanent magnets. The tangential and radial excitation windings are connected in series. The annular sleeve is installed on the outside of the Halbach array annular structure to fix the tangential permanent magnets, radial permanent magnets, tangential excitation windings, and radial excitation windings.

[0009] As a preferred embodiment of the present invention, the outer edge of the rotor core is provided with rotor slots, and the gap between the non-magnetic annular sheath, the outer edge of the tangential permanent magnet, and two adjacent radial permanent magnets forms an excitation winding slot. The radial excitation winding is wound around the radial permanent magnet through the excitation winding slot, and the tangential excitation winding is wound around the tangential permanent magnet through the rotor slot and the excitation winding slot. Both the tangential permanent magnet and the radial permanent magnet are made of AlNiCo permanent magnets.

[0010] An adjustable permanent magnet motor rotor structure based on a Halbach array includes a non-magnetic annular sleeve, tangential permanent magnets, radial permanent magnets, tangential excitation windings, radial excitation windings, a rotor core, and a shaft. The rotor core is fitted onto the shaft. Tangential and radial permanent magnets are alternately arranged to form a Halbach array annular structure. Radial permanent magnets are arranged on the outer edge of the rotor core, with the inner diameter of the radial permanent magnets being the same as the outer diameter of the rotor core. Tangential permanent magnets are embedded inside the rotor core, with the outer diameter of the tangential permanent magnets being the same as the outer diameter of the rotor core, and adjacent tangential permanent magnets having opposite magnetization directions. Adjacent radial permanent magnets have opposite magnetization directions. Tangential excitation windings are wound around tangential permanent magnets, and radial excitation windings are wound around radial permanent magnets. The tangential and radial excitation windings are connected in series. The annular sleeve is installed on the outside of the Halbach array annular structure to fix the tangential permanent magnets, radial permanent magnets, tangential excitation windings, and radial excitation windings.

[0011] As a preferred embodiment of the present invention, a rotor slot is formed on the side of the rotor core that contacts the tangential permanent magnet. The non-magnetic annular sheath, the outer edge of the tangential permanent magnet, and the gap between two adjacent radial permanent magnets form an excitation winding slot. The radial excitation winding is wound around the radial permanent magnet through the excitation winding slot, and the tangential excitation winding is wound around the tangential permanent magnet through the rotor slot and the excitation winding slot. Both the tangential permanent magnet and the radial permanent magnet are made of AlNiCo permanent magnets.

[0012] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0013] This invention addresses the current problem of high cost of permanent magnet materials by using an excitation winding with magnetic adjustment capability in conjunction with AlNiCo permanent magnets to regulate the motor's magnetic field. It replaces the more expensive rare earth materials with lower-cost AlNiCo permanent magnet materials, thus solving the problem of high cost of permanent magnets. By using a Halbach array structure in conjunction with the excitation winding, leakage flux between magnets and the motor's magnetic field can be improved, thereby increasing the utilization rate of permanent magnets and the power density of the motor. Attached Figure Description

[0014] Figure 1 This invention relates to a Halbach permanent magnet motor rotor structure in which the radial permanent magnet outer diameter is the same as the tangential permanent magnet outer diameter.

[0015] Figure 2 This invention relates to a Halbach permanent magnet motor rotor structure in which the outer diameter of the radial excitation permanent magnet is larger than that of the tangential excitation permanent magnet.

[0016] Figure 3 This invention relates to an adjustable permanent magnet motor rotor structure with tangentially magnetized permanent magnets embedded in the permanent magnet.

[0017] Among them, 1 is the annular sheath, 2 is the excitation winding slot, 3 is the tangential permanent magnet, 4 is the radial permanent magnet, 5 is the rotor slot, 6 is the tangential excitation winding, 7 is the radial excitation winding, 8 is the rotor core, and 9 is the shaft. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0019] This invention employs two excitation sources: an excitation winding and a permanent magnet. The permanent magnet can be made of low-cost AlNiCo permanent magnet material, and the permanent magnet adopts a Halbach arrangement. The excitation winding is wound around the AlNiCo permanent magnet. The magnetization degree of the AlNiCo permanent magnet can be changed by adjusting the magnitude and direction of the excitation current, thereby controlling the magnitude of the air gap magnetic field and thus realizing the magnitude of the output torque.

[0020] Figure 1 This is a Halbach permanent magnet motor rotor structure with the same outer diameter for both radial and tangential permanent magnets. The AlNiCo permanent magnets are magnetized radially or tangentially, with alternating magnetization methods arranged closely around the outer edge of the rotor core. Both types of permanent magnets have the same outer diameter. A tangential excitation winding 6 is wound around the tangential permanent magnet 3. The specific magnetization direction is shown by the arrow in the figure; that is, the magnetization directions of two adjacent tangential permanent magnets 3 are opposite, and the magnetization directions of two adjacent radial permanent magnets 4 are opposite. The excitation winding slot 2 and rotor slot 5 between the annular sleeve 1 and the tangential permanent magnet 3 can be used to install the excitation winding. The annular sleeve 1 is installed on the outer edge of the radial permanent magnet to fix the permanent magnet and the excitation winding. The tangential excitation windings 6 are connected in series. When the current direction in each excitation winding element is as follows... Figure 1 When the excitation current is reversed, the magnetic field strength of the AlNiCo permanent magnet is enhanced, thereby increasing the air gap magnetic field strength and increasing the motor torque. When the excitation current is reversed, the magnetic field strength of the AlNiCo permanent magnet is reduced, thereby reducing the air gap magnetic field strength and decreasing the motor torque.

[0021] Figure 2This is a Halbach permanent magnet motor rotor structure where the outer diameter of the radial excitation permanent magnet is larger than that of the tangential excitation permanent magnet. Both magnetization methods use surface-mounted permanent magnets, with the radial excitation permanent magnet having a larger outer diameter than the tangential excitation permanent magnet. AlNiCo permanent magnets of both magnetization methods are arranged alternately. Excitation winding slots are formed between the radially magnetized permanent magnets, the annular sheath, and the smaller-diameter tangentially magnetized permanent magnets. Radial excitation windings are wound on the radially magnetized AlNiCo permanent magnets, and tangential excitation windings are wound on the tangentially magnetized AlNiCo permanent magnets. The specific magnetization directions are shown by the arrows in the figure; that is, the magnetization directions of two adjacent tangential permanent magnets are opposite, and the magnetization directions of two adjacent radial permanent magnets are opposite. The annular sheath is installed on the outer edge of the radial permanent magnet to fix the permanent magnets and excitation windings. Radial excitation windings 7 are connected in series, and tangential excitation windings 6 are connected in series. When the current direction in each excitation winding element is as follows... Figure 2 When the excitation current is reversed, the magnetic field strength of the AlNiCo permanent magnet is enhanced, thereby increasing the air gap magnetic field strength and increasing the motor torque. When the excitation current is reversed, the magnetic field strength of the AlNiCo permanent magnet is reduced, thereby reducing the air gap magnetic field strength and decreasing the motor torque.

[0022] Figure 3 This is a rotor structure for an adjustable permanent magnet motor with tangentially magnetized permanent magnets embedded in the rotor core. Radially magnetized permanent magnets are arranged on the outer edge of the rotor core 8, which is mounted on a shaft 9. The inner diameter of the radially magnetized permanent magnets is the same as the outer diameter of the rotor core. The tangentially magnetized permanent magnets are embedded inside the rotor core, and their outer diameter is the same as the outer diameter of the rotor core. The specific magnetization direction is shown by the arrows in the figure; that is, the magnetization directions of two adjacent tangential permanent magnets are opposite, and the magnetization directions of two adjacent radial permanent magnets are opposite. The tangentially magnetized AlNiCo permanent magnets are embedded inside the rotor core; radial excitation windings are wound on the radially magnetized AlNiCo permanent magnets, and the radial excitation windings are connected in series. Tangential excitation windings are wound on the tangentially magnetized AlNiCo permanent magnets, and the tangential excitation windings are connected in series. When the current direction in each excitation winding element is as follows... Figure 3 When the excitation current is reversed, the magnetic field strength of the AlNiCo permanent magnet is enhanced, thereby increasing the air gap magnetic field strength and increasing the motor torque. When the excitation current is reversed, the magnetic field strength of the AlNiCo permanent magnet is reduced, thereby reducing the air gap magnetic field strength and decreasing the motor torque.

[0023] The tangential excitation winding is wound around the tangential magnetized permanent magnet through the rotor slots and the excitation winding slots, while the radial excitation winding is wound around the radial magnetized permanent magnet through the excitation winding slots on both sides of the radial magnetized permanent magnet.

[0024] Brushless excitation can be achieved by adding an exciter. A rotating armature exciter is mounted coaxially, and the armature winding of the exciter is connected to the excitation winding of the adjustable permanent magnet motor through a rotating rectifier.

[0025] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A rotor structure for an adjustable permanent magnet motor based on a Halbach array, characterized in that, The rotor core comprises a non-magnetic annular sheath, tangential permanent magnets, radial permanent magnets, tangential excitation windings, radial excitation windings, a rotor core, and a shaft. The rotor core is fitted onto the shaft, with tangential and radial permanent magnets arranged alternately to form a Halbach array annular structure. The radial permanent magnets are arranged on the outer edge of the rotor core, and their inner diameter is the same as the outer diameter of the rotor core. The tangential permanent magnets are embedded inside the rotor core, and their outer diameter is the same as the outer diameter of the rotor core. The magnetization directions of two adjacent tangential permanent magnets are opposite, and the magnetization directions of two adjacent radial permanent magnets are also opposite. The tangential excitation winding is wound around the tangential permanent magnets, and the radial excitation winding is wound around the radial permanent magnets. On the permanent magnet, the tangential excitation windings are connected in series, and the radial excitation windings are connected in series. A rotor slot is opened on the side of the rotor core that contacts the tangential permanent magnet. The non-magnetic annular sheath, the outer edge of the tangential permanent magnet, and the gap between two adjacent radial permanent magnets form the excitation winding slot. The radial excitation winding is wound on the radial permanent magnet through the excitation winding slot, and the tangential excitation winding is wound on the tangential permanent magnet through the rotor slot and the excitation winding slot. The annular sheath is installed on the outside of the Halbach array annular structure to fix the tangential permanent magnet, the radial permanent magnet, the tangential excitation winding, and the radial excitation winding. Both the tangential permanent magnet and the radial permanent magnet are made of AlNiCo permanent magnet.

2. The adjustable permanent magnet motor rotor structure based on Halbach array according to claim 1, characterized in that, The tangential and radial excitation windings change the magnetization of the AlNiCo permanent magnet by adjusting the magnitude and direction of the excitation current, thereby controlling the magnitude of the air gap magnetic field. When the excitation currents of the tangential and radial excitation windings are in the same direction, the magnetic field strength of the AlNiCo permanent magnet increases, the air gap magnetic field strength increases, and the motor torque increases. When the excitation currents of the tangential and radial excitation windings are in opposite directions, the magnetic field strength of the AlNiCo permanent magnet decreases, the air gap magnetic field strength decreases, and the motor torque decreases.

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