Permanent magnet synchronous motor

Abstract

The permanent magnet synchronous motor comprises a stator, a rotor and a magnetic isolation bridge, the middle of a tooth part of the stator is an arc, and the two ends of the tooth part are cut flat; a permanent magnet with a V-shaped structure is arranged in the rotor, and the outer circle of the rotor adopts a two-section chamfering design; and the magnetic isolation bridges are arranged between the adjacent rotors and are used for blocking magnetic leakage. The pole-arc coefficient and the effective air gap length of the motor are adjusted by adjusting the excircle shape of the rotor and the tooth tip shape of the stator, so that the air gap flux density harmonic amplitude is reduced, and the cogging torque and the torque ripple of the motor are reduced.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a permanent magnet synchronous motor. Background Technology

[0002] In the prior art, a built-in permanent magnet synchronous motor adopts a "V"-shaped rotor structure to improve the salient pole ratio. By increasing the effective magnet thickness of the motor's d-axis magnetic circuit, the d-axis inductance is reduced, thereby increasing the salient pole ratio and effectively improving the motor's torque capacity. However, while the torque capacity is improved, the magnetic field energy in the motor's air gap also increases with the increase in the amount of permanent magnets used, leading to an increase in the motor's cogging torque and torque fluctuation. Therefore, the structure of this permanent magnet synchronous motor needs to be optimized.

[0003] In conclusion, there is an urgent need for a permanent magnet synchronous motor to solve the current problems. Summary of the Invention

[0004] The purpose of this invention is to provide a permanent magnet synchronous motor that reduces cogging torque and torque ripple by optimizing the motor structure.

[0005] To solve the above-mentioned technical problems, the present invention provides a permanent magnet synchronous motor, comprising:

[0006] The stator has a rounded middle section for the teeth and flat ends for the teeth.

[0007] The rotor has a built-in V-shaped permanent magnet and a two-section chamfered outer circle design.

[0008] A magnetic bridge is placed between adjacent rotors to block magnetic leakage.

[0009] Optionally, the stator adopts a centralized winding configuration, with the winding being a single stator tooth winding structure.

[0010] Optionally, the flattened portion of the stator teeth occupies 0.16 of the total tooth radius, and the angle between the flattened portion and the central axis of the teeth is 86 degrees.

[0011] Optionally, the V-shaped permanent magnet includes an S-pole magnet and an N-pole magnet, wherein the N-pole magnet and the S-pole magnet are spaced apart and uniformly arranged inside the rotor.

[0012] Optionally, the included angle of the V-shaped permanent magnet is 82 degrees to 88 degrees.

[0013] Optionally, the outer circle of the rotor adopts a two-section chamfered design, including a first chamfer and a second chamfer. The first chamfer and the second chamfer are set on the outer circle of the rotor to achieve an irregular shape of the outer ring of the rotor.

[0014] Optionally, the beveled design at both ends forms an irregular shape by first bevel and second bevel at the outer circle position near the two poles of the V-shaped permanent magnet. The midpoint position of the two poles of the V-shaped permanent magnet maintains the original outer circle shape. The two poles of adjacent V-shaped permanent magnets are connected by a small arc segment, which is set higher than the first and second bevels.

[0015] Optionally, the V-shaped permanent magnet has a first chamfer and a second chamfer on both sides of the midpoint of the two poles, and the first chamfer and the second chamfer on both sides are symmetrically arranged.

[0016] Optionally, the height of the first chamfer is 0.9 to 1.1 times the effective air gap length, and the height of the second chamfer is 0.4 to 0.6 times the effective air gap length. The first chamfer and the second chamfer are connected by a smooth curve, and the second chamfer is set close to the two poles of the V-shaped permanent magnet.

[0017] Optionally, the radius of the first chamfer is 0.08 to 0.09 of the extreme arc width, and the radius of the second chamfer is 0.06 to 0.07 of the extreme arc width.

[0018] The permanent magnet synchronous motor provided by this invention adjusts the motor pole arc coefficient and effective air gap length by adjusting the outer circle shape of the rotor and the stator tooth tip shape, thereby reducing the air gap magnetic flux density harmonic amplitude and reducing the cogging torque and torque fluctuation of the motor.

[0019] In addition, the present invention also adjusts the d-axis inductance and reduces motor leakage flux by adjusting the magnetic pole angle and the magnetic isolation bridge pattern of the V-shaped rotor structure, thereby improving the motor salient pole ratio and torque output capability. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of a permanent magnet synchronous motor provided in an embodiment of the present invention; Figure 2 for Figure 1 Schematic diagram of the outer circle of the rotor; Figure 3 The experimental results for the back electromotive force harmonics are shown in the figure. Figure 4 The figure shows the experimental results of cogging torque; Figure 5 The experimental results for the rated output torque are shown in the figure. Figure 6 The figure shows the experimental results of radial force.

[0027] Among them, 1-stator, 2-rotor, 3-V-shaped permanent magnet, 4-weight reduction hole, 5-shaft, Cut1-first chamfer, Cut2-second chamfer, A-center position of outer arc, B-first end point of outer arc, C-second end point of outer arc. Detailed Implementation

[0028] The core of this invention is to provide a permanent magnet synchronous motor. In the prior art, a built-in permanent magnet synchronous motor adopts a "V" type rotor structure. However, while the torque capacity of this motor is improved, the magnetic field energy in the air gap of the motor also increases with the increase of the amount of permanent magnets. The cogging torque and torque fluctuation of the motor also increase accordingly. Therefore, it is necessary to optimize the structure of the permanent magnet synchronous motor.

[0029] The permanent magnet synchronous motor provided by this invention adjusts the motor pole arc coefficient and effective air gap length by adjusting the outer circle shape of the rotor and the stator tooth tip shape, thereby reducing the air gap magnetic flux density harmonic amplitude and reducing the cogging torque and torque fluctuation of the motor.

[0030] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely 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.

[0031] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a permanent magnet synchronous motor provided in an embodiment of the present invention.

[0032] See Figure 1 This invention provides a permanent magnet synchronous motor, comprising:

[0033] Stator 1 has a rounded middle section for the teeth and flat ends for the teeth.

[0034] Rotor 2, with built-in V-shaped permanent magnet 3, and the outer circle adopts a two-section chamfered design;

[0035] A magnetic isolation bridge is placed between adjacent rotors 2 to block magnetic leakage.

[0036] In this embodiment, the rotor 2 is also provided with a weight reduction hole 4, and a rotating shaft 5 is provided at the center of the rotor 2.

[0037] In this embodiment, the permanent magnet synchronous motor is an 8-pole, 12-slot motor, and the outer diameter of the stator 1 is 125mm. The magnetization direction length of the V-shaped permanent magnet 3 is 2.0mm to 2.4mm, the width of the permanent magnet is 14.0mm to 15.0mm, the width of the magnetic isolation bridge between adjacent V-shaped permanent magnets 3 is 1.0mm to 1.4mm, and the height of the magnetic isolation bridge is 0.6mm to 1.0mm. The V-shaped permanent magnet 3 is provided with auxiliary holes, the width of which is 2.0mm to 2.8mm, the length of which is 9.6mm to 10.8mm, and the air gap height between the auxiliary holes is 0.8mm to 1.2mm.

[0038] Furthermore, stator 1 adopts a centralized winding configuration, with the winding being a single stator tooth winding structure.

[0039] In this preferred embodiment, the flattened portion of the stator 1 tooth occupies 0.16 of the total tooth arc, and the angle between the flattened portion of the tooth and the central axis of the tooth is 86 degrees.

[0040] Furthermore, the V-shaped permanent magnet 3 includes an S-pole magnet and an N-pole magnet, which are spaced apart and uniformly arranged inside the rotor 2.

[0041] Furthermore, the included angle of the V-shaped permanent magnet 3 is 82 degrees to 88 degrees. It should be noted that in this embodiment, by adjusting the size of the included angle of the V-shaped permanent magnet 3 and the parameters of the magnetic isolation bridge, the d-axis inductance is adjusted and the leakage flux of the motor is reduced, thereby improving the salient pole ratio and torque output capability of the motor.

[0042] like Figure 2 As shown, the outer circle of rotor 2 adopts a two-section chamfered design, including a first chamfer Cut1 and a second chamfer Cut2. The first chamfer Cut1 and the second chamfer Cut2 are set on the outer circle of rotor 2 to realize the irregular shape of the outer ring of rotor 2.

[0043] Furthermore, the beveled design at both ends forms an irregular shape near the outer circle of the two poles of the V-shaped permanent magnet 3 through a first bevel (Cut1) and a second bevel (Cut2). The midpoint of the two poles of the V-shaped permanent magnet 3 retains the original outer arc. The center position A of the outer arc, the first endpoint B of the outer arc, and the second endpoint C of the outer arc are as follows: Figure 2 As shown, the poles of adjacent V-shaped permanent magnets 3 are connected by a short arc segment, which is set higher than the first chamfered Cut1 and the second chamfered Cut2. In this embodiment, the radius of the short arc segment is slightly higher than the height of the first chamfered Cut1 and the second chamfered Cut2, which can prevent the motor salient pole ratio from decreasing due to excessively low q-axis inductance.

[0044] It should be noted that this embodiment uses chamfering to achieve unequal air gaps, and does not excessively reduce the q-axis (a small arc is provided at the q-axis position). Only a small amount of performance is sacrificed to achieve a significant reduction in cogging torque and torque fluctuation.

[0045] Optionally, a first chamfer Cut1 and a second chamfer Cut2 are provided on both sides of the midpoint of the two poles of the V-shaped permanent magnet 3 (i.e., the center position A of the outer arc). The first chamfer Cut1 and the second chamfer Cut2 on both sides are symmetrically arranged.

[0046] Optionally, the height of the first chamfered corner Cut1 is 0.9 to 1.1 times the effective air gap length, and the height of the second chamfered corner Cut2 is 0.4 to 0.6 times the effective air gap length. The first chamfered corner Cut1 and the second chamfered corner Cut2 are connected by a smooth curve, and the second chamfered corner Cut2 is positioned close to the two poles of the V-shaped permanent magnet 3. The calculation expression for the effective air gap length Airgap_L is as follows:

[0047] Airgap_L=(Stator_d-Rotor_d) / 2;

[0048] Wherein, Stator_d is the inner diameter of the stator, and Rotor_d is the outer diameter of the rotor. Since the outer circle of the rotor in this embodiment is irregularly shaped, the outer diameter of the rotor is the maximum radius of the outer circle of the rotor, that is, the radius of the arc where the midpoint of the two poles of the V-shaped permanent magnet 3 is located.

[0049] Optionally, the radius of the first bevel (Cut1) is 0.08 to 0.09 of the polar arc width, and the radius of the second bevel (Cut2) is 0.06 to 0.07 of the polar arc width. The expression for calculating the polar arc width (Mag_rad) is:

[0050] Mag_rad = 360deg / Poles;

[0051] Where deg represents the unit of angle and Poles represents the number of rotor poles.

[0052] To verify the technical effect of the permanent magnet synchronous motor provided in this embodiment, a comparison was made between an existing motor (a built-in permanent magnet synchronous motor) and the permanent magnet synchronous motor in this embodiment. The difference between the existing motor and the permanent magnet synchronous motor in this embodiment lies in the outer circle shape of the rotor and the shape of the stator teeth. The experimental results are as follows:

[0053] like Figure 3 As shown, compared with the existing motor (existing solution), the back electromotive force harmonic amplitude and harmonic proportion of the motor in this embodiment (new solution) are reduced. The THD (Total Harmonic Distortion) of the existing motor is 9.94%, while the THD of the motor in this embodiment is 4.48%, and the harmonic proportion is reduced by 54.9%.

[0054] like Figure 4 As shown, compared with existing motors, the motor in this embodiment can effectively reduce the cogging torque of the motor, thereby improving the user experience. The cogging torque of the motor in this embodiment is reduced by 91%.

[0055] like Figure 5 As shown, compared with existing motors, the motor in this embodiment can effectively reduce the torque fluctuation of the motor, thereby improving the smoothness of motor operation. The torque fluctuation of the existing motor is 17.52%, while the torque fluctuation of the new solution is 8.25%, a reduction of 52.9%.

[0056] like Figure 6 As shown, compared with existing motors, the motor in this embodiment can effectively reduce the radial force of the motor, thereby reducing the vibration and noise of the motor.

[0057] Based on the above experimental results, it can be seen that the permanent magnet synchronous motor structure of this embodiment can ensure that the cogging torque generated by the permanent magnet motor in the static state and the torque fluctuation in the running state are small, thereby improving the user experience of the motor. The cogging torque of the motor is reduced by 91%, and the torque fluctuation is reduced by 52.9%. In addition, this embodiment can also effectively suppress the radial force density of the motor by opening auxiliary holes in the yoke of the rotor 2.

[0058] The present invention provides a detailed description of a permanent magnet synchronous motor. Specific examples have been used to illustrate the principles and implementation methods of the invention. The descriptions of these embodiments are merely illustrative of the method and core ideas of the invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A permanent magnet synchronous motor, characterized in that, include: The stator has a rounded middle section for the teeth and flat ends for the teeth. The rotor has a built-in V-shaped permanent magnet and a two-section chamfered outer circle design. A magnetic bridge is placed between adjacent rotors to block magnetic leakage.

2. The permanent magnet synchronous motor according to claim 1, characterized in that, The stator adopts a centralized winding configuration, and the winding is a single stator tooth winding structure.

3. The permanent magnet synchronous motor according to claim 1, characterized in that, The flat section of the stator teeth accounts for 0.16 of the total tooth radius, and the angle between the flat section and the central axis of the teeth is 86 degrees.

4. The permanent magnet synchronous motor according to claim 1, characterized in that, The V-shaped permanent magnet includes an S-pole magnet and an N-pole magnet, which are spaced apart and uniformly arranged inside the rotor.

5. The permanent magnet synchronous motor according to claim 1, characterized in that, The included angle of the V-shaped permanent magnet is 82 degrees to 88 degrees.

6. The permanent magnet synchronous motor according to claim 1, characterized in that, The outer circle of the rotor adopts a two-section chamfered design, including a first chamfer and a second chamfer. The first chamfer and the second chamfer are set on the outer circle of the rotor to achieve the irregular shape of the outer ring of the rotor.

7. The permanent magnet synchronous motor according to claim 6, characterized in that, The beveled design at both ends forms an irregular shape by first and second bevels at the outer circle position near the two poles of the V-shaped permanent magnet. The midpoint position of the two poles of the V-shaped permanent magnet maintains the original outer circle shape. The poles of adjacent V-shaped permanent magnets are connected by a small arc segment, which is set higher than the first and second bevels.

8. The permanent magnet synchronous motor according to claim 7, characterized in that, The V-shaped permanent magnet has a first chamfer and a second chamfer on both sides of the midpoint of the two poles, and the first chamfer and the second chamfer on both sides are symmetrically arranged.

9. The permanent magnet synchronous motor according to claim 6, characterized in that, The height of the first chamfer is 0.9 to 1.1 times the effective air gap length, and the height of the second chamfer is 0.4 to 0.6 times the effective air gap length. The first chamfer and the second chamfer are connected by a smooth curve, and the second chamfer is set close to the two poles of the V-shaped permanent magnet.

10. The permanent magnet synchronous motor according to claim 6, characterized in that, The radius of the first chamfer is 0.08 to 0.09 of the extreme arc width, and the radius of the second chamfer is 0.06 to 0.07 of the extreme arc width.

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