Linear Motor Armature Core Length Optimization for Cogging Thrust Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing linear motors experience significant cogging thrust, leading to vibrations, noise, and deteriorations in positioning performance and speed stability, which current techniques fail to adequately address.
Innovation Solution
The linear motor design includes a field core with permanent magnets and an armature core with armature winding wire, where the armature core length is optimized to be between (N×τp−0.2×τp) and (N×τp+0.2×τp), with convex-shaped end teeth and high-density winding wire configuration, and the armature cores are integrated with a top plate to enhance rigidity and reduce magnetic attractive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the armature core length is increased to improve thrust output, then the thrust force increases, but the cogging thrust and vibrations increase
Solution Approach 1:
The patent optimizes the armature core length parameter to satisfy (N×τp−0.2×τp)≤Lc≤(N×τp+0.2×τp), where N is a natural number and τp is the permanent magnet pitch. This parameter optimization reduces cogging thrust while maintaining effective thrust force by ensuring the armature core length is an integer multiple of the permanent magnet pitch, thereby aligning the magnetic flux distribution to minimize harmonic components that cause vibrations.
2Ease of manufacture
If conventional armature core shapes are used to simplify manufacturing, then manufacturing is easier, but positioning performance and speed stability deteriorate
Solution Approach 1:
The patent specifies precise parameter ranges for the armature core length relative to the permanent magnet pitch, ensuring optimal positioning performance and speed stability while maintaining manufacturing feasibility through standardized dimensional relationships.
3Object-generated harmful factors
If the armature core length is optimized to reduce cogging thrust, then vibrations and noise decrease, but the thrust output may be reduced
Solution Approach 1:
The patent achieves a balance between reducing cogging thrust and maintaining thrust output by optimizing the armature core length to satisfy (N×τp−0.2×τp)≤Lc≤(N×τp+0.2×τp). This optimization minimizes harmonic components causing vibrations and noise while preserving the effective interaction between the armature winding and permanent magnets for adequate thrust generation.
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 effectively reduces cogging thrust, improves thrust characteristics, enhances machine stiffness, and simplifies assembly, while minimizing magnetic attractive force and copper loss.
Implementation Method 1
A linear motor includes a stator and an armature core. The stator includes a field core and a plurality of permanent magnets disposed at the field core. The armature core has an armature winding wire.
Implementation Method 2
The linear motor generates a cogging thrust. This cogging thrust causes vibrations and a noise during driving the linear motor.
Data Source
AI summary
A linear motor includes a field core, a stator that includes a plurality of permanent magnets disposed on the field core, and an armature core that includes an armature winding wire, the armature core being disposed via a magnetic void with the permanent magnets. Assuming that a length of the armature core in a traveling direction of the linear motor is Lc, a pitch of the permanent magnets is .tau.p, and N is a natural number, the length Lc of the armature core is specified by (N.times..tau.p-0.2.times..tau.p).ltoreq.Lc.ltoreq.(N.times..tau.p+0.2.ti- mes..tau.p).