Integrated Self-Starting Rotor for Synchronous Motors

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Solution Overview

Problem

The existing production methods for self-starting permanently excited synchronous motors are complex and require precise tolerance specifications, making them inefficient and costly, and they are not suitable for use in chemically aggressive environments.

Innovation Solution

Designing the active rotor part and self-starting means as a single, magnetizable, corrosion-resistant, and electrically conductive component with permanent magnets integrated into axial pockets, surrounded by a ring-shaped area for eddy current conduction, allowing for simpler production and improved rotational behavior.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the rotor is manufactured using traditional multi-step assembly methods with separate ferrite material, permanent magnets, and squirrel cage components, then the starting properties and synchronous operation are achieved, but the manufacturing complexity increases and production time is extended

Engineering Contradiction:
Improvestarting propertiesVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the active rotor part and self-starting means into a single integrated component made of magnetizable, corrosion-resistant, and electrically conductive material. The permanent magnets are integrated directly into the active rotor part, eliminating the need for separate assembly steps and reducing manufacturing complexity while maintaining reliable starting properties and synchronous operation.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The active rotor part is designed to serve multiple functions simultaneously: it provides magnetic conductivity for synchronous operation, electrical conductivity for self-starting via eddy currents, and corrosion resistance for durability. This multi-functionality eliminates the need for separate components and simplifies the overall rotor structure.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If traditional rotor assembly methods are used with multiple components, then the required magnetic and electrical properties are achieved, but the production cost increases and manufacturing precision requirements become more stringent

Engineering Contradiction:
Improvesynchronous operationVSAvoidease of manufacture
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the active rotor part and self-starting means into a single component that can be manufactured as one piece using casting or extrusion processes. This eliminates the need for precise assembly of multiple components and reduces manufacturing precision requirements while maintaining reliable synchronous operation through the integrated design.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent changes the material parameters by selecting a magnetizable, corrosion-resistant, and electrically conductive material that satisfies multiple requirements simultaneously. This material selection enables the single-component design to achieve the necessary magnetic and electrical properties without complex multi-material assembly.

Inventive Principle:
Principle #35Parameter changes

3Use of energy by moving object

If the active rotor part is made of magnetically highly permeable material, then good magnetic properties are achieved, but the rotational behavior deteriorates due to increased torque

Engineering Contradiction:
Improvemagnetic propertiesVSAvoidrotational behavior
Core Design Contradiction:
Use of energy by moving objectVSSpeed

Solution Approach 1:

The patent optimizes the magnetic properties by carefully selecting and tuning the magnetic permeability parameter of the material. The material is designed to have sufficient magnetic conductivity for synchronous operation while maintaining lower torque characteristics that improve rotational behavior and speed response.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If separate components are used for active rotor part and self-starting means, then functional requirements are met, but material usage increases and production time is extended

Engineering Contradiction:
Improvefunctional performanceVSAvoidproduction speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent combines the active rotor part and self-starting means into a single integrated component that can be manufactured in one production process. This eliminates multiple assembly steps and significantly increases production speed while maintaining all necessary functional properties for both starting and synchronous operation.

Inventive Principle:
Principle #5Merging (Combining)

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 simplifies production, reduces material usage, and enhances the rotor's starting properties and efficiency by minimizing magnetic voltage drops and torque, while maintaining energy efficiency and corrosion resistance.

Implementation Method 1

The permanent magnets are surrounded by a ring-shaped area of the active rotor part which is arranged on a larger diameter and conducts eddy currents. This ring-shaped area of the active rotor part thus forms the means for self-starting.

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Implementation Method 2

The permanent magnets unfold their effect in synchronous operation.

Methodology Applied
Scientific EffectMagnetic field interaction: Magnetic Field

Data Source

PatentEP2345138B1Rotor of a self-starting electric motor
Publication Date: 2012.09.19 KSB SE & CO KGAA
  • EP2345138B1 patent drawingFigure 1
  • EP2345138B1 patent drawingFigure 2~3
  • EP2345138B1 patent drawingFigure 4~5

AI summary

The invention relates to a rotor of an electric motor, particularly a permanently excited synchronous motor, having a rotor shaft, a solid active rotor component comprising one or more permanent magnets, and a means for self-starting the electric motor on an alternating current grid. The invention further relates to a method for operating an electric motor having such a rotor. The active rotor component (5) and the means for self-starting is a single piece and made of a single magnetizable, corrosion-resistant, and electrically conductive material. The permanent magnets (3) are integrated in the active rotor component (5). The permanent magnets (3) are surrounded by an annular region (11) of the active rotor component (5) conducting eddy currents and disposed at a larger diameter as a self-starting means.