Linear Machine Primary Part End Tooth Modules Force Ripple

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Solution Overview

Problem

Linear electrical machines experience significant active and passive force ripple, leading to vibrations, unsteady running, and tracking errors due to magnetic interactions at the ends of the primary part, resulting in asymmetric induced voltages and power losses.

Innovation Solution

The primary part is enhanced with flux-guiding end tooth modules that include permanent magnets without windings, arranged to match the geometry of existing tooth modules, allowing for reduced force ripple by modifying the magnetization or size of the permanent magnets at the ends, which compensates for the latching forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the primary part has several active means for generating magnetic fields, then the machine can generate electromagnetic force, but significant active and passive force ripple occurs leading to vibrations and unsteady running

Engineering Contradiction:
Improveelectromagnetic forceVSAvoidforce ripple
Core Design Contradiction:
PowerVSObject-generated harmful factors

Solution Approach 1:

The primary part is segmented into multiple tooth modules, each containing permanent magnets and windings. This segmentation allows the magnetic field generation to be distributed across multiple identical units, which helps to balance and reduce the overall force ripple through the periodic arrangement of these segments along the linear path.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different magnetic field generation approaches at different locations: permanent magnets are installed in all tooth modules including end tooth modules, while windings are only installed in intermediate tooth modules. This local differentiation optimizes the magnetic field distribution to reduce force ripple at critical end regions while maintaining power generation capability in the central region.

Inventive Principle:
Principle #3Local quality

2Power

If the primary part has several active means for generating magnetic fields, then electromagnetic force is generated, but asymmetric induced voltages occur resulting in power losses

Engineering Contradiction:
Improveelectromagnetic forceVSAvoidpower losses
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The primary part is divided into multiple identical tooth modules with consistent permanent magnet installation. This segmentation creates a more uniform magnetic field distribution along the linear path, which symmetrizes the induced voltages in the windings and reduces the asymmetric power losses that would otherwise occur at the ends of the primary part.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Permanent magnets are strategically installed in end tooth modules where they are needed to compensate for the lack of magnetic flux at the ends, while windings are positioned in intermediate modules where they can effectively convert the symmetrized magnetic field into electrical energy with minimal asymmetric losses.

Inventive Principle:
Principle #3Local quality

3Object-generated harmful factors

If flux-guiding end tooth modules with permanent magnets are added, then force ripple is reduced, but the device complexity increases

Engineering Contradiction:
Improveforce rippleVSAvoidstructure complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The primary part is divided into standardized tooth modules that can be manufactured independently and assembled in sequence. The end tooth modules are identical in structure to intermediate modules, differing only in the absence of windings. This modular segmentation simplifies the overall design and manufacturing process while achieving force ripple reduction through the consistent permanent magnet arrangement across all modules.

Inventive Principle:
Principle #1Segmentation

4Power

If permanent magnets are installed in end tooth modules, then induced voltages are enhanced and force ripple is reduced, but manufacturing complexity increases

Engineering Contradiction:
Improveinduced voltagesVSAvoidmanufacturing complexity
Core Design Contradiction:
PowerVSEase of manufacture

Solution Approach 1:

The primary part is constructed from multiple identical tooth modules that can be manufactured using the same tooling and processes. Each module contains permanent magnets installed in the same positions, allowing for standardized manufacturing procedures. The end modules are simply assembled without windings, maintaining ease of manufacture while achieving enhanced induced voltages through the continuous permanent magnet arrangement.

Inventive Principle:
Principle #1Segmentation

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 significantly reduces active and passive force ripple, enhances induced voltages, and improves motor operation by minimizing cogging forces, resulting in better synchronism, higher nominal force, and reduced electromagnetic asymmetries.

Implementation Method 1

a first means for generating a first magnetic field and a second means for generating a second magnetic field

Methodology Applied
Scientific EffectMagnetic field generation: Magnetism

Implementation Method 2

superimposition of the first magnetic Field with the second magnetic field is made possible

Methodology Applied
Scientific EffectMagnetic superimposition: Magnetic Field

Implementation Method 3

By attaching flux-guiding elements, a reduction in the active and especially the passive force ripple

Methodology Applied
Scientific EffectFlux guidance: Magnetic Field

Implementation Method 4

The induced voltages in the winding-carrying end teeth of the primary part are increased

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2091137B1Primary part and linear electrical machine with compensation of force ripples
Publication Date: 2014.06.25 SIEMENS AG
  • EP2091137B1 patent drawingFigure 1~3
  • EP2091137B1 patent drawingFigure 4~5

AI summary

The invention relates to a primary part (2) of a linear electric machine (1, 10, 20), wherein the primary part (2) comprises: - a first means for generating a first magnetic field, - a second means for generating a second magnetic field, - wherein the first means and the second means are arranged in such a way that a superposition of the first magnetic field with the second magnetic field is enabled, - wherein a flux-carrying element for reducing the force ripple is arranged on one and/or both end faces of the primary part (2).