Rotor Magnet Surface Ratios for Low-Cogging Torque Motors
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Solution Overview
Problem
Motors experience significant cogging torque due to differences in magnetic permeability between metal stators and open slots, leading to increased vibration and inefficiency.
Innovation Solution
The motor design includes a rotor core with magnets, where the distance between the magnet's surfaces and the stator teeth is optimized to reduce cogging torque, with specific length ratios and surface configurations, such as a flat third surface and curved second surface, to minimize magnetic interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotor includes a plurality of magnets facing the teeth of the stator, then the motor can generate rotational force through magnetic interaction, but cogging torque is generated due to difference in magnetic permeability between the metal stator and open slots
Solution Approach 1:
The patent applies parameter changes by optimizing the width of the flat surface on the magnet's third surface to be 46%-50% of the width of the first surface of the tooth. This specific dimensional parameter adjustment modifies the magnetic interaction characteristics between the magnet and stator teeth, reducing cogging torque while preserving the motor's rotational force generation capability.
Solution Approach 2:
The patent employs curvature by configuring the second surface of the magnet (the surface contacting the rotor core) as a curved surface that follows the outer circumference of the rotor core. This curved geometry optimizes the magnetic field distribution and reduces abrupt magnetic permeability transitions, thereby minimizing cogging torque effects.
2Reliability
If the magnet includes a flat third surface facing the stator tooth, then the magnetic interaction is optimized, but the distance and dimensional ratios must be precisely controlled to minimize cogging torque
Solution Approach 1:
The patent establishes specific parameter ranges for manufacturing: the first length (width of flat third surface) should be 46%-50% of the second length (width of first surface), and the first length should be 133%-146% of the third length (distance between adjacent teeth). These parameter specifications provide clear manufacturing guidelines that balance magnetic interaction optimization with manufacturability.
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 design effectively reduces cogging torque and motor vibration, improving efficiency and performance by optimizing the magnetic interaction between the rotor and stator.
Implementation Method 1
the rotor includes a rotor core and a magnet disposed on the rotor core, a tooth of the stator includes a first surface facing the magnet
Implementation Method 2
The adjacent teeth are disposed apart from each other to form open slots. In this case, a cogging torque may be generated due to a difference in magnetic permeability between the stator formed of a metal material and the open slot which is an empty space when the rotor rotates.
Data Source
AI summary
The present invention may provide a motor including a rotor and a stator disposed to correspond to the rotor, wherein the rotor includes a rotor core and a magnet disposed on the rotor core, a tooth of the stator includes a first surface facing the magnet, the magnet includes a second surface in contact with the rotor core and a third surface which is spaced apart from the second surface and faces the first surface, the third surface includes a flat surface, and a first length which is a shortest distance of the flat surface is in the range of 46% to 50% of a second length of a shortest distance of the first surface.