Rotating Electrical Machine Cogging Torque Reduction
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Solution Overview
Problem
Rotating electrical machines with permanent magnets experience increased cogging torque due to disturbances in the space magnetic field distribution, particularly when the width of the permanent magnet is greater than the width of the projection, leading to inefficiencies in torque output.
Innovation Solution
A rotating electrical machine design featuring a stator core with tooth portions and a rotor core with projections and permanent magnets, where the gap between the permanent magnet and the projection is equal to or smaller than the width of the tooth portion, optimizing magnetic flux distribution to reduce cogging torque without compromising output torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the width of the permanent magnet is made much greater than the width of the projection to optimize output torque, then output torque is improved, but cogging torque increases due to disturbance in space magnetic field distribution
Solution Approach 1:
The patent changes the geometric parameters of the rotor structure by controlling the gap width between permanent magnets to be equal to or smaller than the tooth portion width. This parameter adjustment optimizes the magnetic field distribution, allowing the permanent magnet width to be increased for higher output torque while preventing excessive cogging torque through proper gap dimensioning.
Solution Approach 2:
The patent applies local quality by creating different regional characteristics in the rotor structure - the gap regions between permanent magnets have specific width constraints that differ from the permanent magnet regions themselves. This local differentiation allows optimization of magnetic flux paths in specific areas, reducing cogging torque in the gap regions while maintaining high output torque from the permanent magnet regions.
2Loss of substance
If permanent magnet materials are reduced to address resource availability, then resource consumption is reduced, but machine size reduction is limited without adequate magnet materials
Solution Approach 1:
The patent optimizes geometric parameters including the gap width between permanent magnets and the projection dimensions to enhance magnetic flux utilization efficiency. By controlling these parameters, the design achieves better performance from reduced permanent magnet material, allowing machine size reduction while maintaining adequate output capability despite using less rare-earth magnet material.
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 effectively reduces cogging torque by ensuring suitable magnetic bypass and leakage flux reduction, maintaining output torque while enhancing efficiency and reducing the machine's size.
Implementation Method 1
The permanent magnets are fixed to the boss portion. Each permanent magnet is located between and spaced from adjacent projections to form a gap in the circumferential direction.
Implementation Method 2
The winding is wound in a slot between the tooth portions. The rotation shaft extends through the stator core and rotatably supported by the supporting member.
Implementation Method 3
optimizing magnetic flux distribution to reduce cogging torque without compromising output torque
Data Source
AI summary
A rotating electrical machine includes a stator core, a rotor core, and permanent magnets. The stator core includes a yoke and tooth portions projecting from the yoke in a radial inward direction. Each tooth portion has a base joined to the yoke and an end opposite to the base. The rotor core includes a boss portion and projections. The projections project from the boss portion in a radial outward direction and spaced in a circumferential direction. Each permanent magnet is located between and spaced from adjacent projections to forma gap in the circumferential direction. A width of the gap is not greater than a width of the end of the tooth portion in the circumferential direction.