Permanent magnet hub asymmetric V-shaped built-in external rotor motor
By designing an asymmetric V-shaped magnet group in the permanent magnet hub outer rotor motor to increase the magnetoresistive torque, the problems of poor expansion capability of weak magnetism and torque fluctuations are solved, and the performance and efficiency of the motor are improved.
Patent Information
- Application Number
- CN202510521482.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-24
- Publication Date
- 2025-06-27
AI Technical Summary
The existing permanent magnet hub outer rotor motors have torque fluctuations, noise and vibration problems during weak magnetic expansion, and the weak magnetic expansion ability is poor.
A permanent magnet hub asymmetric V-type built-in external rotor motor is designed. Multiple permanent magnet units are built on the outer rotor, and are composed of V-type magnetic steel groups. Each pole is asymmetric. The intersection-axis inductance is greater than the direct-axis inductance, which has a convex pole effect, increases magnetoresistance torque, and improves the weak magnetic speed expansion ability.
By increasing the magnetoresistive torque, the motor superimposes the magnetoresistive torque on the basis of the permanent magnet torque, improving the weak magnetic speed expansion ability, reducing noise and torque fluctuations, and improving the starting characteristics, overload capacity and power density of the motor.
Smart Images
Figure CN120222672A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of motors, and particularly to a technology of a permanent magnet hub asymmetric V-type built-in outer rotor motor. Background Art
[0002] The air gap diameter of the outer rotor motor is larger than that of the inner rotor, and it has high power factor, high efficiency, high output torque and moment of inertia, and is suitable for applications in low-speed, high-torque and direct drive occasions. However, the cogging torque of the permanent magnet hub motor will cause speed and torque fluctuations, resulting in technical problems such as motor noise, vibration and operation deterioration.
[0003] Such as Figure 2 As shown, existing outer rotor motors are all surface-mounted permanent magnet synchronous motors (SPMSM), mainly composed of an inner stator 72 and an annular outer rotor 71. The inner stator is located in the annular hole of the outer rotor, and the inner stator and the outer rotor are in clearance fit. On the inner ring surface of the outer rotor 71, surface-mounted tile-shaped permanent magnets 73 protruding radially inward are evenly distributed. Since the magnetic permeability of the permanent magnet of this surface-mounted outer rotor permanent magnet synchronous motor is close to that of air, the direct and quadrature axis air gaps are uniform, and the direct and quadrature axis inductances are equal (Ld = Lq), which belongs to a non-salient pole magnetic circuit and does not generate reluctance torque. Moreover, due to the relatively large equivalent air gap, it is difficult to solve the field weakening and speed increase problem. It is necessary to pass a large direct axis current through the stator winding to achieve the purpose of field weakening and speed increase. This method will reduce the torque, increase the stator loss, reduce the efficiency of the drive system, and may cause the irreversible demagnetization risk of the permanent magnet. The poor field weakening and speed increase ability is the fundamental reason hindering the development of SPMSM. Summary of the Invention
[0004] Aiming at the defects existing in the above-mentioned prior art, the technical problem to be solved by the present invention is to provide a permanent magnet hub asymmetric V-type built-in outer rotor motor that can reduce motor noise and torque fluctuations.
[0005] To solve the above technical problem, a permanent magnet hub asymmetric V-type built-in outer rotor motor provided by the present invention includes an inner stator and an outer rotor. A plurality of permanent magnet units are built in the outer rotor, and each permanent magnet unit is symmetrically arranged around the rotating shaft of the outer rotor. It is characterized in that: the permanent magnet unit includes a V-type magnet group, and the V-type magnet group is composed of two straight bar magnets symmetrically arranged relative to the d-axis. In the V-type magnet group, let the width of the straight bar magnet on the counterclockwise side of the d-axis be a, and the width of the straight bar magnet on the clockwise side of the d-axis be b, then a > b.
[0006] Furthermore, in the V-type magnet group, a middle permanent magnet slot is provided between the adjacent ends of the two straight bar magnets, and side permanent magnet slots are provided at the non-adjacent ends of the two straight bar magnets.
[0007] Further, in the V-shaped permanent magnet group, pole shoe holes are formed in the pole shoe part between two linear permanent magnets.
[0008] Further, semi-circular grooves are formed in the end faces of the stator teeth of the inner stator.
[0009] The permanent magnet hub asymmetric V-shaped built-in outer rotor motor provided by the present invention has a salient pole structure for the outer rotor, with a V-shaped permanent magnet group built inside the outer rotor, and the V-shaped permanent magnet group is asymmetric for each pole, such that the quadrature-axis inductance is greater than the direct-axis inductance, having a salient pole effect, enabling the motor to superimpose reluctance torque on the basis of permanent magnet torque. The presence of reluctance torque helps with field weakening and speed increase, featuring good field weakening and speed increasing capabilities, capable of improving the starting characteristics, overload capacity, and power density of the motor, expanding the constant power range operation, and obtaining better field weakening and speed increasing capabilities. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 is a schematic radial cross-sectional view of the permanent magnet hub asymmetric V-shaped built-in outer rotor motor according to an embodiment of the present invention; Figure 2 Schematic radial cross-sectional view of the stator and rotor of a conventional surface-mounted outer rotor permanent magnet synchronous motor. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0011] The following further describes the embodiments of the present invention in detail with reference to the accompanying drawings. However, these embodiments do not limit the present invention. Any similar structures and their similar variations using the present invention shall fall within the protection scope of the present invention. The commas in the present invention all represent the relationship of "and".
[0012] As Figure 1-2 shown, a permanent magnet hub asymmetric V-shaped built-in outer rotor motor provided by an embodiment of the present invention includes an inner stator 1 and an outer rotor 2. A plurality of permanent magnet units are built inside the outer rotor 2, and each permanent magnet unit is symmetrically arranged around the rotating shaft of the outer rotor; The permanent magnet unit includes a V-shaped permanent magnet group, which is composed of two linear permanent magnets 21 symmetrically arranged with respect to the d-axis. And in the V-shaped permanent magnet group, a middle permanent magnet slot 22 is provided between the adjacent ends of the two linear permanent magnets 21, side permanent magnet slots 23 are provided at the non-adjacent ends of the two linear permanent magnets 21, and pole shoe holes 24 are formed in the pole shoe part between the two linear permanent magnets, reducing the magnetic field distortion caused by armature reaction, improving the air-gap magnetic field waveform, and reducing torque ripple; In the V-shaped permanent magnet group, let the width of the linear permanent magnet on the counterclockwise side of the d-axis be a, and the width of the linear permanent magnet on the clockwise side of the d-axis be b, then a > b; Semi-circular grooves 12 are formed in the end faces of the stator teeth of the inner stator.
[0013] The motor with a permanent magnet outer rotor of this embodiment is compared with an existing outer rotor surface-mounted permanent magnet hub motor of the same specification. The parameters of the existing motor with an internal double-layer U-shaped permanent magnet rotor are: rated power is 3KW, rated current is 19.5A, efficiency is 91.5%, rated speed is 800r / min, maximum speed is 2000r / min, rated torque is 35.8Nm, and maximum torque is 78Nm; Compared with the existing outer rotor surface-mounted permanent magnet hub motor of the same specification, the motor with a permanent magnet outer rotor of this embodiment of the present invention has an efficiency increased from 91.5% to 95.0%, cogging torque decreased from 1.75Nm to 0.72Nm, cogging torque ripple decreased from 4.9% to 2.0%, and constant power speed regulation range increased from 800 - 2000r / min to 800 - 2800r / min.
[0014] It can be seen that this embodiment of the present invention improves the air-gap magnetic flux density waveform and reduces motor noise and torque ripple.
Claims
1. A permanent magnet hub asymmetric V-shaped internal outer rotor motor, comprising an inner stator and an outer rotor, wherein the outer rotor has a plurality of permanent magnet units built therein, and each permanent magnet unit is symmetrically arranged around the rotation axis of the outer rotor, characterized in that: The permanent magnet unit includes a V-shaped magnetic steel group, which is composed of two straight magnetic steels symmetrically arranged relative to the d axis. Assuming that in the V-shaped magnetic steel group, the width of the straight magnetic steel located on the counterclockwise side of the d axis is a, and the width of the straight magnetic steel located on the clockwise side of the d axis is b, then a>b.
2. The permanent magnet hub asymmetric V-shaped internal outer rotor motor according to claim 1, characterized in that: In the V-shaped magnetic steel group, a middle permanent magnetic groove is arranged between the adjacent ends of two straight-shaped magnetic steels, and a side permanent magnetic groove is arranged at the non-adjacent ends of two straight-shaped magnetic steels.
3. The permanent magnet hub asymmetric V-shaped internal outer rotor motor according to claim 1, characterized in that: In the V-shaped magnetic steel group, a pole shoe hole is provided at the pole shoe portion between two straight-shaped magnetic steels.
4. The permanent magnet hub asymmetric V-shaped internal outer rotor motor according to claim 1, characterized in that: Each stator tooth end surface of the inner stator is provided with a semicircular groove.