Permanent magnet hub motor mixed magnetic pole surface-mounted outer rotor
By alternately arranging magnets of different shapes in the permanent magnet hub motor to form an asymmetrical air gap, the noise and vibration problems caused by the cogging torque fluctuation are solved, thereby improving motor efficiency and reducing noise.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI TOP MOTOR
- Filing Date
- 2025-04-24
- Publication Date
- 2026-04-24
AI Technical Summary
The cogging torque of a permanent magnet hub motor generates speed and torque fluctuations, leading to motor noise and vibration problems.
The permanent magnet hub motor uses a hybrid magnetic pole surface-mounted external rotor with alternating A-type and B-type magnets. The A-type magnets are arc-shaped in the radial section, while the B-type magnets are bread-shaped with a thicker middle and thinner sides, forming an asymmetrical air gap to improve the air gap magnetic field waveform.
It effectively reduces torque ripple, improves motor efficiency, and reduces noise and vibration.
Smart Images
Figure CN224164712U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of motor technology, and in particular to a technology for a permanent magnet hub motor with a hybrid magnetic pole surface-mounted external rotor. Background Technology
[0002] The air gap diameter of the external rotor motor is larger than that of the internal rotor, which has a high power factor, high efficiency, high output torque and rotational inertia. It is suitable for low-speed, high-torque and direct drive applications. 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 deterioration of operation. Utility Model Content
[0003] In view of the defects existing in the prior art, the technical problem to be solved by this utility model is to provide a permanent magnet hub motor with a hybrid magnetic pole surface-mounted external rotor that can reduce motor noise and torque fluctuation.
[0004] To solve the above-mentioned technical problems, this utility model provides a permanent magnet hub motor hybrid magnetic pole surface-mounted external rotor, including a rotor core, wherein multiple magnets are attached to the inner ring surface of the rotor core, characterized in that:
[0005] There are two types of magnets attached to the inner ring surface of the rotor core: type A magnets and type B magnets. Type A magnets and type B magnets are arranged alternately around the shaft of the outer rotor.
[0006] The type A magnet is arc-shaped in the radial section of the rotor core, and the type B magnet is bread-shaped with a thick middle and thin sides in the radial section of the rotor core. Let the distance between the inner side of the type A magnet and the rotor core axis be R1, and the distance between the inner side of the type B magnet and the rotor core axis be R2, then R1=R2.
[0007] The permanent magnet hub motor with a hybrid magnetic pole surface-mounted external rotor provided by this utility model uses surface-mounted magnets of different shapes arranged alternately. One set of magnets forms a uniform air gap with the stator, while the other set of magnets forms a non-uniform air gap with the stator. The air gaps at both ends are large and the air gap in the middle is small, forming an asymmetry between adjacent magnetic poles, which can effectively reduce torque fluctuations and improve the air gap magnetic field waveform of the motor. Attached Figure Description
[0008] Figure 1 This is a radial cross-sectional schematic diagram of the surface-mounted outer rotor of the permanent magnet hub motor according to an embodiment of this utility model. Detailed Implementation
[0009] The embodiments of this utility model are described in further detail below with reference to the accompanying drawings. However, these embodiments are not intended to limit this utility model. Any similar structures or variations thereof that adopt this utility model should be included in the protection scope of this utility model. The commas in this utility model all indicate a relationship between and.
[0010] like Figure 1 As shown in the figure, the permanent magnet hub motor hybrid magnetic pole surface-mounted external rotor provided by this utility model embodiment includes a rotor core 2, wherein a plurality of magnets are attached to the inner ring surface of the rotor core 2, characterized in that:
[0011] There are two types of magnets attached to the inner ring surface of the rotor core 2: type A magnet 3 and type B magnet 4. Type A magnets and type B magnets are arranged alternately around the shaft of the outer rotor.
[0012] The type A magnet 3 is arc-shaped in the radial section of the rotor core, and the type B magnet 4 is bread-shaped with a thick middle and thin sides in the radial section of the rotor core. Let the distance between the inner side of the type A magnet 3 and the rotor core axis be R1, and the distance between the inner side of the type B magnet 4 and the rotor core axis be R2, then R1=R2.
[0013] In this embodiment of the invention, type A magnet 3 forms a uniform air gap with the stator, while type B magnet 4 forms a non-uniform air gap with the stator. The air gaps at both ends of type B magnet are large, while the air gap in the middle is small, resulting in asymmetry between adjacent magnetic poles. This effectively reduces torque fluctuations and improves the air gap magnetic field waveform of the motor.
[0014] The permanent magnet external rotor motor of this embodiment was compared with the existing external rotor surface-mounted permanent magnet hub motor of the same specification. The parameters of the existing built-in double-layer U-shaped permanent magnet rotor motor are: rated power of 3KW, rated current of 19.5A, efficiency of 91.5%, rated speed of 800r / min, maximum speed of 2000r / min, rated torque of 35.8Nm, and maximum torque of 78Nm.
[0015] Compared with existing surface-mounted permanent magnet hub motors of the same specifications, the motor with the permanent magnet external rotor of this utility model has an efficiency that increases from 91.5% to 93.8%, a cogging torque that decreases from 1.75 Nm to 0.82 Nm, and a cogging torque fluctuation that decreases from 4.9% to 2.3%.
[0016] Therefore, the present invention improves the air gap flux density waveform and reduces motor noise and torque fluctuation.
Claims
1. A permanent magnet hub motor with a hybrid magnetic pole surface-mounted external rotor, comprising a rotor core, wherein a plurality of magnets are attached to the inner annular surface of the rotor core, characterized in that: There are two types of magnets attached to the inner ring surface of the rotor core: type A magnets and type B magnets. Type A magnets and type B magnets are arranged alternately around the shaft of the outer rotor. The type A magnet is arc-shaped in the radial section of the rotor core, and the type B magnet is bread-shaped with a thick middle and thin sides in the radial section of the rotor core. Let the distance between the inner side of the type A magnet and the rotor core axis be R1, and the distance between the inner side of the type B magnet and the rotor core axis be R2, then R1=R2.