Rotor Edge Notches Reduce Cogging Torque in Permanent Magnet Motors
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Solution Overview
Problem
Conventional permanent magnet motors experience cogging torque issues due to magnetic attraction between the stator and rotor structures, which hinder rotor rotation.
Innovation Solution
The rotor structure incorporates edge notches with obliquely arranged magnet slots and notches along its outer edge, allowing for extended magnetic fields that reduce cogging torque and enhance operational efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If magnets are arranged in alternating V-shape pairs to increase magnetic forcing, then the magnetic forcing is improved, but cogging torque increases and acts against rotor rotation
Solution Approach 1:
The rotor structure is segmented by introducing notches that divide the rotor body into multiple sections. These notches create distinct magnetic zones that help control and distribute the magnetic fields more evenly, reducing the harmful cogging torque while maintaining the beneficial magnetic forcing from the V-shape magnet pairs.
Solution Approach 2:
The notches are positioned asymmetrically relative to the magnet slots, creating an optimized magnetic path that balances the magnetic forcing requirements with cogging torque reduction. The asymmetric design allows magnetic fields to extend more effectively to the stator while preventing excessive attraction forces.
2Force
If magnets are arranged in V-shape pairs, then magnetic forcing is enhanced, but the structural complexity of the rotor increases
Solution Approach 1:
The invention merges multiple functions into the rotor structure: the V-shape magnet pairs provide magnetic forcing, while the integrated notches simultaneously manage magnetic field distribution and reduce cogging torque. This combination achieves enhanced performance without proportionally increasing structural complexity.
Solution Approach 2:
The rotor structure applies different features at different locations: V-shape magnet pairs are positioned where strong magnetic forcing is needed, while notches are strategically placed in specific regions to control magnetic field extension and reduce cogging torque locally, optimizing overall performance.
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
The rotor structure with edge notches significantly reduces cogging torque and improves the operational efficiency of permanent magnet motors by effectively extending magnetic fields to the stator.
Implementation Method 1
the magnetic fields induced by the magnets at the first magnet slots and the second magnet slots can be further extended to effectively reach the stator
Implementation Method 2
the attraction between the magnetic polarity of the coils at the stator structure and that of the magnets at the rotor structure
Data Source
AI summary
A rotor structure includes a rotor body and a plurality of magnets. The rotor body has a plurality of surrounding magnet-setting areas, and each magnet setting area has a first magnet slot and a second magnet slot symmetrically arranged to a centripetal axis. A first outer end of the first magnet slot and a second outer end of the second magnet slot are close to the centripetal axis and rotor's outer edge. A first outer end of the first magnet slot and a second outer end of the second magnet slot are distant to the centripetal axis and rotor's outer edge. The outer edge has a plurality of notches intersected by the corresponding centripetal axes. The magnets are respectively fixed to the first magnet slots and the second magnet slots of the magnet-setting areas.