High power density permanent magnet torque motor and design method thereof

Abstract

The application belongs to the field of electric machines, and discloses a high-power-density permanent-magnetic torque motor and a design method thereof. The permanent magnet (3) is in a built-in structure on the stator side and is inlaid in the stator core (1); the stator core (1) and the rotor core (4) both adopt a salient pole structure; the three-phase stator winding adopts a concentrated winding structure; the permanent magnets (3) are uniformly distributed in the stator core (1), the three-phase stator winding (2) is wound on the stator core (1), the stator core (1) is composed of steel sheets which are stacked along the axial direction, the number of poles of the stator core (1) is 12, and the number of slots is 28. The application solves the problems of low power torque density, large torque ripple and easy over-temperature demagnetization of the permanent magnet in the existing permanent-magnetic torque motor, effectively suppresses the torque ripple of the permanent-magnetic motor, and improves the demagnetization resistance of the permanent magnet.

Description

Technical Field

[0001] This invention belongs to the field of electric motors; specifically, it relates to a high power density permanent magnet torque motor and its design method. Background Technology

[0002] Permanent magnet torque motors, with their ability to directly drive loads, eliminate the need for traditional transmission devices and possess excellent low-speed, high-torque characteristics, making them widely used in low-speed, direct-drive, high-torque applications. Among them, stator permanent magnet torque motors, in particular, boast advantages such as simple structure, high power density, and resistance to demagnetization due to over-temperature, making them crucial in various fields. my country has placed higher demands on motor drive equipment used in aerospace, electric vehicles, and ship propulsion, as well as in manufacturing equipment such as CNC machine tools and industrial robots, requiring miniaturization, high power density, high precision, and fast response speed. On the one hand, the loss of the mechanical amplification effect of a mechanical reducer increases the system's torque output capability, necessitating higher power density from permanent magnet torque motors. On the other hand, ensuring precise control of the target by the servo system under various conditions also places higher demands on the motor's torque ripple. The power density of existing permanent magnet torque motors still needs improvement, and significant problems such as large cogging torque and load torque fluctuations urgently need to be addressed. Therefore, improving the power density of permanent magnet torque motors and reducing their torque ripple has become a hot research topic in this field.

[0003] Extensive research has been conducted by domestic and international research institutions on permanent magnet torque motors. Existing technologies have improved the motor's torque density. However, this motor structure exhibits significant torque ripple, failing to meet the high control precision requirements of systems. Existing technologies have improved power density through rational motor structure design. However, this structure also suffers from significant torque ripple. Existing technologies have effectively reduced torque ripple by rationally designing the combination of stator and auxiliary tooth materials and tooth width ratio. However, this structure increases the motor's equivalent air gap, thereby reducing torque density and simultaneously increasing cost and manufacturing complexity. In conclusion, existing permanent magnet motors cannot simultaneously meet the current industrial development requirements for both high power density and low torque ripple. Summary of the Invention

[0004] This invention provides a high power density permanent magnet torque motor and its design method to solve the problems of low power torque density, large torque ripple, and easy demagnetization of permanent magnets due to overheating in existing permanent magnet torque motors.

[0005] This invention is achieved through the following technical solution:

[0006] A high power density permanent magnet torque motor, the permanent magnet torque motor comprising a stator core 1, permanent magnets 3, a three-phase stator winding 2, and a rotor core 4;

[0007] The three-phase stator winding 2 includes an A-phase stator winding 21, a B-phase stator winding 22, and a C-phase stator winding 23, wherein the A-phase stator winding 21, the B-phase stator winding 22, and the C-phase stator winding 23 adopt a concentrated winding structure.

[0008] The permanent magnet 3 is an embedded structure on the stator side, embedded in the stator core 1; both the stator core 1 and the rotor core 4 adopt a salient pole structure; the permanent magnet 3 is evenly distributed inside the stator core 1, and the three-phase stator winding 2 is wound on the stator core 1; the stator core 1 is made of steel sheets stacked along the axial direction; the stator core 1 has 12 poles and 28 slots.

[0009] A high power density permanent magnet torque motor, wherein four permanent magnets 3 are installed under the teeth of each stator core 1, the magnetization direction of the permanent magnets 3 is radial magnetization, the outermost edge of the permanent magnets 3 is aligned with the edge of the pole shoe of the stator core 1, and the axial length of the permanent magnets 3 is equal to the axial length of the stator core 1.

[0010] A design method for a high power density permanent magnet torque motor, wherein the polarities of two adjacent permanent magnets 3 are opposite; the arrangement order of the permanent magnets 3 under the teeth of two adjacent stator cores 1 is opposite; each permanent magnet 3 has a circular ring structure, and the distance from the lower surface of the permanent magnet 3 to the center of the ring is R. in The distance from the upper surface of the permanent magnet 3 to the center of the circle is R. out Along the circumferential direction of the motor, the mechanical angle corresponding to a single permanent magnet 3 is α. A section of stator core 1 is introduced between two adjacent permanent magnets 3 on the teeth of the same stator core 1, and the mechanical angle corresponding to the stator core 1 is β.

[0011] A design method for a high power density permanent magnet torque motor, wherein the mechanical angle α corresponding to the single permanent magnet 3 satisfies the following formula:

[0012]

[0013] In the formula p s p represents the number of stator side pole pairs. r f(2p) represents the number of rotor-side pole pairs. s 2p r ) represents 2p s and 2p r The least common multiple of .

[0014] A design method for a high power density permanent magnet torque motor, wherein a small section of the stator core 1 is introduced between two adjacent permanent magnets 3 on the teeth of the same stator core 1, and the mechanical angle β corresponding to the stator core 1 satisfies the following formula:

[0015]

[0016] A design method for a high power density permanent magnet torque motor, wherein, with a single stator core 1, the magnetomotive force generated by the permanent magnet 3 is related to the mechanical angle α corresponding to the permanent magnet 3 and the air gap angle β between the permanent magnets 3; the magnetomotive force corresponding to the P-pole permanent magnet 3 is F0, the magnetomotive force corresponding to the N-pole permanent magnet 3 is -F0, and the magnetomotive force corresponding to the region between adjacent permanent magnets 3 is 0; the expression F(θ) for the magnetomotive force with a single stator core 1 satisfies:

[0017]

[0018] A design method for a high power density permanent magnet torque motor, wherein the rotor core 4 includes a main rotor tooth 41 and an auxiliary rotor tooth 42; the mechanical angle corresponding to the main rotor tooth 41 is γ, the mechanical angle corresponding to the auxiliary rotor tooth 42 is δ, and γ>δ; the mechanical angle corresponding to the air gap between the main rotor tooth and the auxiliary rotor tooth is (25.71°-γ-δ).

[0019] The mechanical angle γ corresponding to auxiliary rotor tooth 42 satisfies:

[0020]

[0021] The mechanical angle δ corresponding to auxiliary rotor tooth 42 satisfies:

[0022]

[0023] A design method for a high power density permanent magnet torque motor, wherein the polarities of two adjacent permanent magnets 3 are opposite, specifically, the polarity of the permanent magnet 3 under the teeth of a single stator core 1 is NSNS or SNSN.

[0024] A design method for a high power density permanent magnet torque motor, wherein the arrangement order of the permanent magnets 3 under the teeth of two adjacent stator cores 1 is reversed, specifically, the arrangement order of the permanent magnets under the adjacent stators is NSNS-SNSN-NSNS-…-SNSN.

[0025] A design method for a high power density permanent magnet torque motor, wherein the polarity of the four permanent magnets under each stator tooth is arranged as NSNS or SNSN; the arrangement order of the permanent magnets under two adjacent stator teeth is the same, that is, the arrangement order of the permanent magnets under adjacent stators is NSNS-NSNS-…-NSNS.

[0026] The beneficial effects of this invention are:

[0027] This invention reduces the complexity of fixing permanent magnets by using an array-arranged embedded permanent magnet structure on the stator side, significantly reduces the effective length of the air gap, and improves the power density, output torque, and demagnetization resistance of the permanent magnets.

[0028] This invention improves the sinusoidal nature of the air gap magnetic field by arranging the embedded permanent magnets.

[0029] The permanent magnet torque motor of the present invention adopts a rotor core with a combined tooth structure on the rotor side. By cooperating with the embedded permanent magnets arranged in an array on the stator side, the sinusoidal nature of the back EMF is improved, the cogging torque is reduced, and the torque pulsation of the permanent magnet motor is effectively suppressed.

[0030] The frequency of the back EMF is determined by the rotor rotation speed. The periodic overlap of the motor stator and rotor causes the magnetic reluctance in the main magnetic flux path to change periodically, which not only changes the magnitude of the main magnetic flux but also changes the direction of the main magnetic path, thereby generating an induced EMF in the stator winding.

[0031] The permanent magnet of this invention adopts an embedded structure, which improves the demagnetization resistance of the permanent magnet compared with the traditional rotor permanent magnet torque motor. Attached Figure Description

[0032] Appendix Figure 1 This is a schematic diagram of the structure of the present invention.

[0033] Appendix Figure 2 This is a schematic diagram of the stator structure of the present invention.

[0034] Appendix Figure 3 This is a schematic diagram of the distribution of the magnetomotive force of the permanent magnet in this invention.

[0035] Appendix Figure 4 This is a schematic diagram of the rotor structure of the present invention.

[0036] Appendix Figure 5 This is a waveform diagram of the no-load magnetic flux linkage of the stator-side A-phase winding of the present invention.

[0037] Appendix Figure 6 This is a comparison diagram of the no-load back EMF waveform of the A-phase winding in the present invention and the traditional permanent magnet torque motor.

[0038] Appendix Figure 7 This is a comparison chart of the load torque of the present invention and a traditional permanent magnet torque motor.

[0039] Appendix Figure 8 This is a schematic diagram of the structure of the stator-side permanent magnets of the present invention when they are arranged in an NSNS-NSNS configuration.

[0040] Stator core 1; Stator winding 2; A-phase stator winding 21; B-phase stator winding 22; C-phase stator winding 23; Embedded permanent magnet 3; Rotor core 4; Main rotor teeth 41; Auxiliary rotor teeth 42. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] A high power density permanent magnet torque motor, the permanent magnet torque motor comprising a stator core 1, permanent magnets 3, a three-phase stator winding 2, and a rotor core 4;

[0043] The three-phase stator winding 2 includes an A-phase stator winding 21, a B-phase stator winding 22, and a C-phase stator winding 23, wherein the A-phase stator winding 21, the B-phase stator winding 22, and the C-phase stator winding 23 adopt a concentrated winding structure.

[0044] The permanent magnet 3 is an embedded structure on the stator side. The permanent magnet is made of neodymium iron boron material and is embedded in the stator core 1. Both the stator core 1 and the rotor core 4 adopt a salient pole structure. The permanent magnet 3 is evenly distributed inside the stator core 1. The stator core 1 is wound with a three-phase stator winding 2. The stator core 1 is made of steel sheets stacked along the axial direction, preferably silicon steel sheets. The stator core 1 has 12 poles and 28 slots.

[0045] The stator core is made of silicon steel sheets, which are stacked along the axial direction. The three-phase stator winding adopts a concentrated winding structure, which is wound around the pole of the stator core to generate a rotating magnetic field in the air gap of the motor. After interacting with the main magnetic field generated by the permanent magnet, it generates electromagnetic torque to drive the motor rotor to rotate. The rotor core is made of silicon steel sheets stacked along the axial direction. The rotor has 28 teeth on its outer circumference, and the permanent magnet changes the air gap permeability.

[0046] When the rotor rotates, the change in magnetic permeability caused by the rotor teeth will change the magnetic flux passing through the stator winding, thereby generating a back electromotive force in the stator winding. The rotor consists of main rotor teeth and auxiliary rotor teeth. The mechanical angle corresponding to the main rotor teeth is larger than that of the auxiliary rotor teeth. Along the rotor axial direction, the main rotor teeth and auxiliary rotor teeth are arranged alternately. Their function is to change the distribution of air gap magnetic permeability along the circumferential direction. By cooperating with the embedded permanent magnet, the sinusoidal nature of the back electromotive force is improved, the cogging torque is reduced, and torque pulsation is suppressed.

[0047] A high power density permanent magnet torque motor, wherein four permanent magnets 3 are installed under the teeth of each stator core 1, the magnetization direction of the permanent magnets 3 is radial magnetization, the outermost edge of the permanent magnets 3 is aligned with the edge of the pole shoe of the stator core 1, and the axial length of the permanent magnets 3 is equal to the axial length of the stator core 1.

[0048] A design method for a high power density permanent magnet torque motor, wherein the polarities of adjacent permanent magnets 3 are opposite, that is, the polarity of the permanent magnet 3 under the teeth of a single stator core 1 is NSNS or SNSN; the arrangement order of the permanent magnets 3 under the teeth of two adjacent stator cores 1 is opposite, that is, the arrangement order of the permanent magnets under the teeth of adjacent stators is NSNS-SNSN-NSNS-…; a single permanent magnet 3 is a ring structure, and the distance from the lower surface of the permanent magnet 3 to the center of the ring is R. in The distance from the upper surface of the permanent magnet 3 to the center of the circle is R. out Along the circumferential direction of the motor, the mechanical angle corresponding to a single permanent magnet 3 is α. A small section of stator core 1 is introduced between two adjacent permanent magnets 3 on the teeth of the same stator core 1, and the mechanical angle corresponding to the stator core 1 is β. This improves the magnetomotive force distribution in the air gap of the motor, thereby improving the sinusoidal nature of the air gap magnetic field, while also reducing the amount of permanent magnets used and lowering costs.

[0049] A design method for a high power density permanent magnet torque motor, wherein the polarity of the four permanent magnets under each stator tooth is arranged as NSNS or SNSN; the arrangement order of the permanent magnets under two adjacent stator teeth is the same, that is, the arrangement order of the permanent magnets under adjacent stators is NSNS-NSNS-…-NSNS.

[0050] A design method for a high power density permanent magnet torque motor, wherein the mechanical angle α corresponding to the single permanent magnet 3 satisfies the following formula:

[0051]

[0052] In the formula p s p represents the number of stator side pole pairs. r f(2p) represents the number of rotor-side pole pairs. s 2p r ) represents 2p s and 2p r The least common multiple of .

[0053] A design method for a high power density permanent magnet torque motor, wherein a small section of the stator core 1 is introduced between two adjacent permanent magnets 3 on the teeth of the same stator core 1, and the mechanical angle β corresponding to the stator core 1 satisfies the following formula:

[0054]

[0055] At this point, while taking into account both the saturation magnetic flux density of the stator core and the change in magnetic permeability caused by the opening of the rotor teeth, the stator core effectively suppresses torque pulsation by changing the magnetomotive force waveform.

[0056] A design method for a high power density permanent magnet torque motor, wherein, with a single stator core 1, the magnetomotive force generated by the permanent magnet 3 is related to the mechanical angle α corresponding to the permanent magnet 3 and the air gap angle β between the permanent magnets 3; the magnetomotive force corresponding to the P-pole permanent magnet 3 is F0, the magnetomotive force corresponding to the N-pole permanent magnet 3 is -F0, and the magnetomotive force corresponding to the region between adjacent permanent magnets 3 is 0; the expression F(θ) for the magnetomotive force with a single stator core 1 satisfies:

[0057]

[0058] A design method for a high power density permanent magnet torque motor, wherein the rotor core 4 includes a main rotor tooth 41 and an auxiliary rotor tooth 42; the mechanical angle corresponding to the main rotor tooth 41 is γ, the mechanical angle corresponding to the auxiliary rotor tooth 42 is δ, and γ>δ; the mechanical angle corresponding to the air gap between the main rotor tooth and the auxiliary rotor tooth is (25.71°-γ-δ).

[0059] The mechanical angle γ corresponding to auxiliary rotor tooth 42 satisfies:

[0060]

[0061] The mechanical angle δ corresponding to auxiliary rotor tooth 42 satisfies:

[0062]

[0063] A design method for a high power density permanent magnet torque motor, wherein the polarities of two adjacent permanent magnets 3 are opposite, specifically, the polarity of the permanent magnet 3 under the teeth of a single stator core 1 is NSNS or SNSN.

[0064] A design method for a high power density permanent magnet torque motor, wherein the arrangement order of the permanent magnets 3 under the teeth of two adjacent stator cores 1 is reversed, specifically, the arrangement order of the permanent magnets under the adjacent stators is NSNS-SNSN-NSNS-…-SNSN.

[0065] The following is in conjunction with the appendix Figure 1 To be continued Figure 7 To explain in detail;

[0066] To address the shortcomings of existing technologies, the objective of this invention is achieved as follows:

[0067] As attached Figure 1As shown, the high power density permanent magnet torque motor of this invention consists of four parts: a stator core, stator-side embedded permanent magnets, three-phase stator windings, and a rotor core. Both the stator and rotor adopt a salient pole structure; the base slot configuration is 12 poles and 28 slots; the permanent magnets adopt an embedded structure, are made of neodymium iron boron material, and are directly embedded in the stator core, allowing heat to be directly transferred to the stator core. Compared with traditional rotor permanent magnet torque motors, this improves the demagnetization resistance of the permanent magnets; compared with the traditional surface-mounted structure, the embedded permanent magnet structure reduces the equivalent air gap of the motor, increasing the power density and output torque, and reducing the amount of permanent magnets used while maintaining the same output torque; the stator core is made of silicon steel sheets, stacked axially; the three-phase stator windings adopt a concentrated winding structure. The rotor core is wound around the poles of the stator core to generate a rotating magnetic field in the air gap of the motor. After interacting with the main magnetic field generated by the permanent magnet, it produces electromagnetic torque, driving the motor rotor to rotate. The rotor core is made of silicon steel sheets stacked axially. The rotor has 28 teeth on its outer circumference. The permanent magnet changes the air gap permeability. When the rotor rotates, the change in permeability caused by the rotor teeth will change the magnetic flux passing through the stator winding, thereby generating a back electromotive force in the stator winding. The rotor consists of main rotor teeth and auxiliary rotor teeth. The mechanical angle of the main rotor teeth is larger than that of the auxiliary rotor teeth. Along the rotor axial direction, the main rotor teeth and auxiliary rotor teeth are arranged alternately. Their function is to change the distribution of air gap permeability along the circumferential direction. By cooperating with the embedded permanent magnet, the sinusoidal nature of the back electromotive force is improved, the cogging torque is reduced, and torque pulsation is suppressed.

[0068] Appendix Figure 2 A schematic diagram of the stator structure of the high power density permanent magnet torque motor of the present invention is provided. As can be seen from the diagram, in the stator-side embedded permanent magnets of the present invention, a total of four permanent magnets are installed under each stator tooth. The magnetization direction of the permanent magnets is radial. The edge of the outermost permanent magnet is aligned with the edge of the stator core pole shoe, and the axial length of the permanent magnet is equal to the axial length of the stator core. The polarities of adjacent permanent magnets are opposite, that is, the polarity of the permanent magnet under a single stator tooth is NSNS or SNSN. The arrangement order of the permanent magnets under adjacent stator teeth is opposite, that is, the arrangement order of the permanent magnets under adjacent stators is NSNS-SNSN-NSNS-…. Each permanent magnet adopts a ring structure, and the distance from its lower surface to the center of the ring is R. in The distance from the upper surface to the center of the circle is R. out Along the circumferential direction of the motor, the mechanical angle corresponding to a single permanent magnet is α. A small section of stator core is introduced between two adjacent permanent magnets on the same stator tooth, and the mechanical angle corresponding to the stator core is β. This is used to improve the distribution of magnetomotive force in the air gap of the motor, thereby improving the sinusoidal nature of the air gap magnetic field. At the same time, it can reduce the amount of permanent magnets used and reduce costs.

[0069] Appendix Figure 3A schematic diagram of the magnetomotive force (MTF) distribution of the permanent magnets in the permanent magnet torque motor of the present invention is given. Under a single stator, the MMF generated by the permanent magnets is related to the mechanical angle α corresponding to the permanent magnets and the air gap angle β between the permanent magnets; the MMF in the region corresponding to the P-pole permanent magnet is F0, the MMF in the region corresponding to the N-pole permanent magnet is -F0, and the MMF in the region between adjacent permanent magnets is 0; the expression for the MMF F(θ) under a single stator satisfies:

[0070]

[0071] Appendix Figure 4 A schematic diagram of the rotor structure in the permanent magnet torque motor of the present invention is given. As can be seen from the figure, the rotor of the present invention is composed only of silicon steel sheet core. The mechanical angle corresponding to the main rotor teeth is γ, and the mechanical angle corresponding to the auxiliary rotor teeth is δ, and γ>δ; the mechanical angle corresponding to the air gap between the main rotor teeth and the auxiliary rotor teeth is (25.71°-γ-δ); the frequency of the back electromotive force is determined by the rotor rotation speed. The periodically overlapping stator and rotor of the motor cause the magnetic reluctance in the main magnetic flux path to change periodically, which not only changes the magnitude of the main magnetic flux, but also changes the direction of the main magnetic path, thereby generating an induced electromotive force in the stator winding.

[0072] Appendix Figure 5 The unloaded flux linkage waveform of the stator A-phase winding in the motor of this invention is shown. It can be seen that as the rotor rotates through one rotor pole pitch, the flux linkage linking the stator phase winding changes for one electrical cycle. As the rotor rotates, this changes periodically. The periodic overlap of the stator and rotor causes a periodic change in the magnetic reluctance in the main magnetic flux path. The magnetic flux generated by the permanent magnet produces a periodic permanent magnet flux linkage in the stator winding. (See attached diagram.) Figure 6 The figures show the no-load back EMF waveforms of the A-phase winding in the motor of this invention and in a conventional permanent magnet torque motor. As can be seen from the figures, the embedded permanent magnet structure significantly reduces the effective length of the air gap, thus increasing the power density and output torque of the motor compared to a conventional permanent magnet torque motor. The back EMF in the A-phase winding increases by approximately 1.6 times for the same dimensions. Furthermore, in the motor of this invention, the rotor core with a combined tooth structure, in conjunction with the embedded permanent magnets arranged in an array on the stator side, improves the sinusoidal nature of the back EMF. Compared to a conventional permanent magnet torque motor, the no-load back EMF waveform in the A-phase winding is approximately sinusoidal, with significantly reduced harmonic content, thereby effectively suppressing torque pulsation in the motor.

[0073] Figure 7This is a comparison diagram of the load torque of the motor of the present invention and a traditional permanent magnet torque motor. As can be seen from the diagram, the permanent magnet torque motor of the present invention can effectively increase the load torque within the same volume and has a higher power density. At the same time, the permanent magnet torque motor of the present invention effectively reduces torque pulsation by rationally designing the arrayed embedded permanent magnets and the combined tooth rotor core structure, thus solving the shortcomings of low power density and large torque fluctuation in existing permanent magnet torque motors.

[0074] To reduce torque ripple and eliminate high-order harmonic components in the stator magnetomotive force, the high power density permanent magnet torque motor of this invention, in summary, has a mechanical angle α corresponding to a single permanent magnet that satisfies:

[0075]

[0076] In the formula p s p represents the number of stator side pole pairs. r f(2p) represents the number of rotor-side pole pairs. s 2p r ) represents 2p s and 2p r The least common multiple of;

[0077] Furthermore, for a single stator, the mechanical angle β corresponding to the stator core between two adjacent permanent magnets satisfies:

[0078]

[0079] At this point, the stator core can effectively suppress torque pulsation by changing the magnetomotive force waveform, while taking into account both the saturation magnetic flux density of the stator core and the magnetic permeability changes caused by the rotor tooth opening.

[0080] To further reduce torque ripple, the rotor teeth in the permanent magnet torque motor of this invention need to be optimized. This invention proposes a rotor core structure formed by the combination of main rotor teeth and auxiliary rotor teeth. By cooperating with the embedded permanent magnets arranged in an array on the stator side, the sinusoidal nature of the back EMF is improved, the cogging torque is reduced, and the torque ripple of the permanent magnet motor is effectively suppressed.

[0081] The mechanical angle γ corresponding to the main rotor teeth satisfies:

[0082]

[0083] The mechanical angle δ corresponding to the auxiliary rotor teeth satisfies:

[0084]

[0085] Compared to the equally spaced rotor teeth in traditional permanent magnet torque motors, the rotor core of this invention uses a combined tooth structure consisting of main rotor teeth and auxiliary rotor teeth to change the previously periodically distributed air gap magnetic permeability. By cooperating with the embedded permanent magnets arranged in an array on the stator side, it improves the sinusoidal nature of the back EMF, reduces the cogging torque, and effectively suppresses the torque pulsation of the permanent magnet motor.

[0086] Appendix Figure 8 A schematic diagram of the permanent magnet torque motor of the present invention is provided when the stator-side embedded permanent magnets are arranged in an NSNS-NSNS pattern. As can be seen from the diagram, in this specific embodiment, the polarity of the four permanent magnets under each stator tooth remains unchanged, still arranged in an NSNS or SNSN pattern; however, the arrangement order of the permanent magnets under adjacent stator teeth is the same, i.e., the arrangement order of the permanent magnets under adjacent stator teeth is NSNS-NSNS-…; except for the arrangement of the stator-side embedded permanent magnets, the rest of the structure is the same as… Figure 1 The motor shown remains unchanged.

[0087] This motor consists of a stator side and a rotor core with embedded permanent magnets. Building upon the direct-drive load and low-speed, high-torque characteristics of traditional permanent magnet torque motors, the permanent magnet torque motor of this invention firstly reduces the complex manufacturing process required for fixing permanent magnets in traditional rotor permanent magnet motors by employing an array-arranged embedded permanent magnet structure on the stator side. Heat from the permanent magnets can be directly transferred to the casing for heat dissipation, improving demagnetization resistance and solving the problem of permanent magnets easily demagnetizing due to overheating in traditional permanent magnet torque motors. Secondly, the embedded permanent magnet structure significantly reduces the effective length of the air gap, increasing the motor's power density and output torque. By rationally designing the spacing of the embedded permanent magnets, harmonic components in the stator excitation magnetomotive force are reduced, improving the sinusoidal nature of the air gap magnetic field. Furthermore, the permanent magnet torque motor described in this invention employs a rotor core with a combined tooth structure on the rotor side. By utilizing the cooperation of the main rotor teeth and auxiliary teeth, the air gap magnetic permeability of the motor is altered. Through cooperation with the embedded permanent magnets arranged in an array on the stator side, the sinusoidal nature of the back EMF is improved, the cogging torque is reduced, and the positioning torque is weakened. Compared to traditional permanent magnet torque motors, this effectively suppresses torque pulsation in permanent magnet motors.

Claims

1. A method of designing a high power density permanent magnet torque motor, characterized by, The permanent magnet torque motor comprises a stator core (1), permanent magnets (3), three-phase stator windings (2) and a rotor core (4); The three-phase stator windings (2) comprise A-phase stator windings (21), B-phase stator windings (22) and C-phase stator windings (23), and the A-phase stator windings (21), B-phase stator windings (22) and C-phase stator windings (23) adopt a concentrated winding structure; The permanent magnets (3) are in a stator-side embedded structure and are inlaid in the stator core (1); the stator core (1) and the rotor core (4) both adopt a salient pole structure; the stator core (1) is uniformly distributed with the permanent magnets (3), the three-phase stator windings (2) are wound on the stator core (1), the stator core (1) is composed of steel sheets stacked along an axial direction, the stator core (1) has 12 poles and 28 slots; Four permanent magnets (3) are installed under each tooth of the stator core (1), the permanent magnets (3) are magnetized in a radial direction, the outermost edge of the permanent magnets (3) is aligned with the edge of a pole shoe of the stator core (1), and the axial length of the permanent magnets (3) is equal to the axial length of the stator core (1). The polarities of two adjacent permanent magnets (3) are opposite; the arrangement sequence of the permanent magnets (3) under the teeth of two adjacent stator cores (1) is opposite; the single permanent magnet (3) is a circular ring structure, the distance from the lower surface of the permanent magnet (3) to the center is R in , the distance from the upper surface of the permanent magnet (3) to the center is R out ; along the circumferential direction of the motor, the corresponding mechanical angle of the single permanent magnet (3) is α , a section of the stator core (1) is introduced between two adjacent permanent magnets (3) on the teeth of the same stator core (1), and the corresponding mechanical angle of the stator core (1) is β .

2. The method of designing a high power density permanent magnet torque motor of claim 1, wherein, The corresponding mechanical angle of the single piece of the permanent magnet (3) is α satisfies the following equation: (1) wherein p s denotes the number of pole pairs on the stator side, p r denotes the number of pole pairs on the rotor side, f (2 p s ,2 p r ) denotes the least common multiple of 2 p s and 2 p r .

3. The method of designing a high power density permanent magnet torque motor of claim 2, wherein, A small stator core (1) is introduced between two adjacent permanent magnets (3) on the teeth of the same stator core (1), and the corresponding mechanical angle of the stator core (1) is β satisfies the following formula: (2)。 4. The method of designing a high power density permanent magnet torque motor of claim 1, wherein, The magnetic motive force generated by the permanent magnet (3) and the mechanical angle corresponding to the permanent magnet (3) under the single stator core (1) α The air gap angle between the permanent magnet (3) β Corresponding to the magnetic motive force of the P-pole permanent magnet (3) in the corresponding area is F 0, the magnetic motive force of the N-pole permanent magnet (3) in the corresponding area is F 0, and the magnetic motive force in the corresponding area between adjacent permanent magnets (3) is 0; the expression of the magnetic motive force under the single stator core (1) F ( θ ) satisfies: (3)。 5. The method of designing a high power density permanent magnet torque motor of claim 1, wherein, The rotor core (4) comprises main rotor teeth (41) and auxiliary rotor teeth (42); the corresponding mechanical angle of the main rotor teeth (41) is γ , the corresponding mechanical angle of the auxiliary rotor teeth (42) is δ , and γ >δ ; the corresponding mechanical angle of the air gap between the main rotor teeth and the auxiliary rotor teeth is (25.71°- γ - δ ). The corresponding mechanical angle of the auxiliary rotor tooth (42) is γ satisfies: (4) The corresponding mechanical angle of the auxiliary rotor tooth (42) is δ satisfies: (5)。 6. The method of designing a high power density permanent magnet torque motor of claim 1, wherein, The polarities of two adjacent permanent magnets (3) are opposite, and specifically, the polarities of the permanent magnets (3) under a single stator core (1) are NSNS or SNSN.

7. The method of designing a high power density permanent magnet torque motor of claim 1, wherein, The arrangement sequence of the permanent magnets (3) under two adjacent stator cores (1) is opposite, and specifically, the arrangement sequence of the permanent magnets under adjacent stator cores is NSNS-SNSN-NSNS-…-SNSN.

8. The method of designing a high power density permanent magnet torque motor of claim 1, wherein, The polarities of the four permanent magnets under each stator tooth are arranged as NSNS or SNSN; the arrangement sequence of the permanent magnets under two adjacent stator teeth is the same, that is, the arrangement sequence of the permanent magnets under adjacent stator teeth is NSNS-NSNS-…-NSNS.

Images