Surface Magnet Rotor Protrusion Layout for Low Torque Ripple
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Solution Overview
Problem
In surface magnet type rotors, increasing the protrusion length for improved magnet fixing stability leads to larger magnetic field distortion, resulting in increased cogging torque, torque ripple, noise, and vibration.
Innovation Solution
A rotor design with magnets oriented in a parallel orientation, where the easy magnetization direction is parallel to the radial direction, and a protrusion that supports more than half of the magnet's circumferential side face, positioned within a specific area to minimize magnetic flux leakage and distortion, ensuring effective magnetic flux and fixing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the protrusion length is increased to improve magnet fixing stability, then the fixing stability of permanent magnets is improved, but the magnetic field distortion becomes larger
Solution Approach 1:
The invention changes the geometric parameters of the protrusion, specifically positioning its front end within a predetermined area defined by the magnet's center line and crossing ridge portion. This parameter optimization allows the protrusion to support more than half of the circumferential side face area, ensuring fixing stability while controlling magnetic field distortion within acceptable levels.
2Reliability
If the protrusion length is increased to improve magnet fixing stability, then the fixing stability of permanent magnets is improved, but the cogging torque and torque ripple increase
Solution Approach 1:
By optimizing the protrusion length and positioning its front end within the predetermined area, the invention achieves a balance where the protrusion provides sufficient mechanical support for magnet stability while minimizing interference with the magnetic field distribution, thereby controlling cogging torque and torque ripple within acceptable ranges.
3Reliability
If the protrusion length is increased to improve magnet fixing stability, then the fixing stability of permanent magnets is improved, but the noise and vibration of the motor increase
Solution Approach 1:
The optimized protrusion design with the front end positioned within the predetermined area reduces magnetic field distortion, which directly decreases cogging torque and torque ripple. This in turn suppresses the noise and vibration generated by the motor while maintaining adequate magnet fixing stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration maintains desired fixing stability while suppressing magnetic field distortion, reducing cogging torque, torque ripple, noise, and vibration, ensuring efficient motor performance.
Implementation Method 1
a plurality of permanent magnets (33) arranged on an outer peripheral surface (32b) of the rotor core (32) with an easy magnetization direction parallel to a radial direction of a center of the permanent magnets (33)
Implementation Method 2
the position of a front end (35t) of the protrusion (35) in the protrusion direction is arranged within a predetermined area extending from a center line (L1) of the circumferential side face (33d) of the permanent magnet (33) in the protrusion direction to a crossing ridge portion (33h) where a connection surface (33e) and the circumferential side face (33d) of the permanent magnet (33) cross each other
Data Source
AI summary
A rotor, motor and brushless motor are provided. This rotor (9) includes a rotor core (32), permanent magnets (33), and a protrusion (35) protruding radially outward between permanent magnets (33). The permanent magnets (33) has a parallel orientation in which the easy magnetization direction is parallel to the radial direction in the center of the permanent magnets (33). The circumferential side faces (33d) of the permanent magnets (33) contact the protrusion (35) in the circumferential direction. Connection surfaces (33e) of the permanent magnets (33) are connected to the circumferential side face (33d) and to the outer peripheral surface (33a) on the radial outer side. The front end (35t) of the protrusion (35) in the protrusion direction is arranged between the center (33g) of the circumferential side face (33d) in the protrusion direction and the crossing ridge portion (33h) where the circumferential side face (33d) and the connection surface (33e) cross.