Permanent magnet hub motor built-in groove-added external rotor motor
By building a V-shaped magnet group and opening arc grooves on the outer rotor of the permanent magnet hub motor, an uneven air gap is formed and the magnetoresistive torque is increased, the problems of motor noise and torque fluctuations are solved, and the weak magnetic speed expansion capability and the overall performance of the motor are improved.
Patent Information
- Application Number
- CN202510521856.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-24
- Publication Date
- 2025-06-13
AI Technical Summary
The cogging torque of existing permanent magnet hub motors will generate rotational speed and torque fluctuations, resulting in deterioration of motor noise, vibration and operation, and poor weak magnetic speed expansion capabilities.
A permanent magnet hub motor built-in groove-increasing outer rotor motor is designed. Multiple V-shaped magnet steel groups are built on the outer rotor, and arc-shaped grooves are opened on the inner annular surface of the outer rotor, and semicircular grooves are opened on the end surface of the inner stator stator teeth to form an uneven air gap, increase the magnetoresistance torque, and improve the weak magnetic speed expansion ability.
By increasing the magnetoresistive torque, the motor noise and torque fluctuations are reduced, the motor start characteristics, overload capacity and power density are improved, the constant power range operation is expanded, and the weak magnetic speed expansion capability is improved.
Smart Images
Figure CN120150402A_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 motor with an internal increased-slot 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 a 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 noise, vibration and deteriorated operation of the motor.
[0003] Such as Figure 2 As shown, existing outer rotor motors are all surface-mounted permanent magnet synchronous motors (SPMSM), which mainly consist 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 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), it 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 in 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 motor with an internal increased-slot outer rotor motor that can reduce the noise and torque fluctuation of the motor.
[0005] To solve the above technical problem, a permanent magnet hub motor with an internal increased-slot outer rotor motor provided by the present invention includes an inner stator and an outer rotor. A plurality of V-shaped magnet groups symmetrically arranged around the rotating shaft of the outer rotor are built in the outer rotor. The V-shaped magnet group is composed of two linear magnets symmetrically arranged relative to the d-axis. Its characteristics are as follows: A plurality of arc-shaped grooves are arranged at intervals along the circumferential direction of the inner ring surface of the outer rotor. The arc-shaped grooves are grouped in threes, and the three arc-shaped grooves in the same group are symmetrically arranged relative to the d-axis.
[0006] Further, semi-circular grooves are provided at the end faces of the stator teeth of the inner stator.
[0007] Further, in the V-shaped magnet group, side permanent magnet grooves are provided at the non-adjacent ends of the two linear magnets.
[0008] The permanent magnet hub motor provided by the present invention is an internal slot-added outer rotor motor. The outer rotor adopts a salient pole structure, with V-shaped permanent magnets built inside the outer rotor, and circular grooves are opened on the surface of the pole shoes, forming an uneven air gap with the stator, so 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 existence of reluctance torque helps with field weakening and speed increasing, having the characteristic of good field weakening and speed increasing ability, which can improve the starting characteristics, overload capacity and power density of the motor, expand the constant power range operation, and obtain better field weakening and speed increasing ability. Description of the Drawings
[0009] Figure 1 is a schematic radial cross-sectional view of the permanent magnet hub motor with internal slot-added outer rotor according to the embodiment of the present invention; Figure 2 Schematic diagram of the stator and rotor radial cross-section of the existing surface-mounted outer rotor permanent magnet synchronous motor. Detailed Embodiments
[0010] 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 changes using the present invention should be included in the protection scope of the present invention. The commas in the present invention all represent the relationship of "and".
[0011] As Figure 1 shown, a permanent magnet hub motor with internal slot-added outer rotor provided by an embodiment of the present invention includes an inner stator 1 and an outer rotor 2. A plurality of V-shaped permanent magnet groups 21 symmetrically arranged around the rotating shaft of the outer rotor 2 are built inside the outer rotor 2. The V-shaped permanent magnet group 21 is composed of two linear permanent magnets symmetrically arranged relative to d. And in the V-shaped permanent magnet group 21, side permanent magnet slots 22 are provided at the non-adjacent ends of the two linear permanent magnets; The inner ring surface of the outer rotor 2 is provided with a plurality of arc-shaped grooves 23 arranged at intervals along the circumferential direction of the outer rotor. The arc-shaped grooves 23 are grouped in threes, and the three arc-shaped grooves 23 in the same group are symmetrically arranged relative to d; Semicircular grooves 12 are opened on the end faces of the stator teeth of the inner stator.
[0012] The motor with the permanent magnet outer rotor of this embodiment is compared with the 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 the permanent magnet outer rotor according to the embodiment of the present invention has its efficiency increased from 91.5% to 94.8%, the cogging torque decreased from 1.75 Nm to 0.78 Nm, the cogging torque ripple decreased from 4.9% to 2.17%, and the constant power speed regulation range increased from 800 - 2000 r / min to 800 - 2800 r / min.
[0013] It can be seen that the embodiment of the present invention improves the air-gap flux density waveform and reduces the motor noise and torque ripple.
Claims
1. A permanent magnet hub motor with an internal slotted outer rotor, comprising an inner stator and an outer rotor, wherein the outer rotor is provided with a plurality of V-shaped magnetic steel groups symmetrically arranged around the rotating axis of the outer rotor, wherein the V-shaped magnetic steel group is composed of two straight magnetic steels symmetrically arranged relative to the d axis, and characterized in that: The inner annular surface of the outer rotor is provided with a plurality of arcuate grooves spaced apart along the circumference of the outer rotor, the arcuate grooves form a group of three, and the three arcuate grooves in the same group are symmetrically arranged relative to the d axis.
2. The permanent magnet hub motor with internal slotted outer rotor according to claim 1, characterized in that: Each stator tooth end surface of the inner stator is provided with a semicircular groove.
3. The permanent magnet hub motor with internal slotted outer rotor according to claim 1, characterized in that: In the V-shaped magnetic steel group, non-adjacent ends of two straight-shaped magnetic steels are both provided with side permanent magnetic grooves.