Permanent Magnet Motor Rotor Core Projections for Torque and Noise Reduction
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Solution Overview
Problem
In permanent magnet motors, the leakage magnetic flux to locking pieces reduces motor torque and increases physical size, leading to vibration noise and irregular rotation.
Innovation Solution
A rotor core design with projections having specific dimensions, where the first projecting portion is longer and taller than the second, allowing precise positioning of permanent magnets and reducing leakage flux, thereby minimizing torque reduction and physical size increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If permanent magnets are positioned on rotor core with T-shaped locking pieces, then positioning precision is improved, but leakage magnetic flux increases causing torque reduction
Solution Approach 1:
The locking piece is segmented into two distinct portions: a first locking portion that contacts the permanent magnet for positioning, and a second locking portion that is separated from the permanent magnet. This segmentation allows the first portion to provide precise positioning while the second portion provides structural support without causing leakage flux, thereby resolving the contradiction between positioning precision and torque maintenance.
Solution Approach 2:
Different portions of the locking piece are designed with different properties: the first locking portion is positioned to make contact with the permanent magnet for precise localization, while the second locking portion is separated to avoid magnetic interference. This local differentiation of function and structure allows the system to achieve both precise positioning and minimal torque loss.
2Strength
If large projections are used between permanent magnets, then structural support is improved, but leakage magnetic flux increases requiring larger motor size
Solution Approach 1:
The locking piece is divided into two functional portions: the first locking portion provides necessary structural support through controlled contact with the permanent magnet, while the second locking portion is separated to minimize magnetic flux leakage. This segmentation allows adequate structural support with reduced material and smaller motor size.
Solution Approach 2:
The design changes the geometric parameters of the locking piece, specifically creating a separated structure where the second locking portion is positioned away from the permanent magnet. This parameter change reduces the magnetic path length for leakage flux while maintaining structural integrity, thereby reducing the required motor size.
3Stability of the object's composition
If permanent magnets are held in abutment against locking pieces, then positioning stability is improved, but irregular rotation increases causing vibration noise
Solution Approach 1:
The locking piece is segmented such that the first locking portion provides stable positioning through contact with the permanent magnet, while the second locking portion is separated to reduce magnetic interference and flux leakage. This segmentation maintains positioning stability while minimizing the harmful effects of irregular rotation and vibration noise.
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 design reduces vibration noise, maintains motor torque, and decreases motor size, improving steering feel and reducing material costs and weight.
Implementation Method 1
there is generated a leakage magnetic flux corresponding to a magnetic flux of the permanent magnets, which originally flows to a stator core to generate a torque
Implementation Method 2
a stator including an armature winding and a stator core having slots configured to accommodate the armature winding therein
Data Source
AI summary
In a permanent magnet motor, projections each include a second projecting portion and a first projecting portion separated away from a side surface of a permanent magnet. When the first projecting portion has a total length L1 in an axial line direction and a height t1, and when the second projecting portion has a total length L2 in the axial line direction and a height t2, (L1×t1)>(L2×t2) is satisfied. As a result, the permanent magnet motor capable of reducing vibration noise of the motor by reducing irregular rotation, reducing decrease in motor torque, and further reducing increase in motor physical size can be obtained.