Rotating Electric Machine Stator Segmentation for Torque and Cost

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Solution Overview

Problem

Large rotating electrical machines require a significant number and size of magnets, leading to high costs for equipping and potentially inefficient operation due to heating and space constraints.

Innovation Solution

A rotating electrical machine design where the rotor lacks magnetic components, with electromagnets and permanent magnets arranged on opposite sides of a reaction element, optimizing slot geometry and reducing heating losses, allowing for modular and cost-effective configuration of active segments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a large number and size of magnets are used in large rotating electric machines, then the magnetic field strength and torque capability are improved, but the cost of the magnet assembly increases significantly

Engineering Contradiction:
Improvetorque capabilityVSAvoidmagnet cost
Core Design Contradiction:
PowerVSQuantity of substance

Solution Approach 1:

The stator is divided into multiple active segments, each containing a limited number of permanent magnets and electromagnets. This segmentation allows the machine to achieve required torque through distributed magnetic fields rather than requiring a single large magnet assembly, thereby reducing overall magnet quantity and cost while maintaining power output.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent combines permanent magnets and electromagnets within the same active segments of the stator. This merging allows the permanent magnets to provide a baseline magnetic field while electromagnets provide controllable additional flux, achieving high torque capability with fewer permanent magnets than would be required using permanent magnets alone.

Inventive Principle:
Principle #5Merging (Combining)

2Power

If electromagnets and permanent magnets are arranged in the same active part of the machine, then the magnetic circuit is strengthened, but the available space for electromagnet coil windings is reduced

Engineering Contradiction:
Improvemagnetic circuit strengthVSAvoidcoil winding space
Core Design Contradiction:
PowerVSVolume of moving object

Solution Approach 1:

The patent arranges electromagnets and permanent magnets in different spatial dimensions within the stator structure. Electromagnets are positioned in slots with dedicated coil winding spaces, while permanent magnets are mounted on the stator yoke surface. This dimensional separation allows both magnetic field sources to coexist without compromising coil winding space, maintaining magnetic circuit strength while enabling adequate space for electromagnetic coils.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Power

If electromagnets and permanent magnets are arranged on the same side of the reaction element, then the magnetic interaction is maximized, but the permanent magnets are significantly heated by the electromagnets

Engineering Contradiction:
Improvemagnetic interaction efficiencyVSAvoidpermanent magnet heating
Core Design Contradiction:
PowerVSTemperature

Solution Approach 1:

The patent introduces the stator yoke and magnetic circuit structures as intermediary elements between electromagnets and permanent magnets. These intermediaries conduct and distribute magnetic flux from both sources, maintaining strong magnetic interaction while physically separating the permanent magnets from the heat-generating electromagnet coils. This allows efficient magnetic coupling while protecting permanent magnets from thermal damage.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Power

If electromagnets and permanent magnets are arranged on the same side of the reaction element, then the magnetic field interaction is enhanced, but the attractive force on the reaction element increases bearing load

Engineering Contradiction:
Improvemagnetic field interactionVSAvoidattractive force on reaction element
Core Design Contradiction:
PowerVSForce

Solution Approach 1:

The patent employs a balanced arrangement where electromagnets and permanent magnets are distributed around the stator circumference in multiple active segments. This distribution creates opposing magnetic forces that counterbalance each other, reducing the net attractive force on the reaction element while maintaining strong magnetic field interaction for torque generation. The counterbalancing effect reduces bearing loads without sacrificing power output.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

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 improves efficiency, reduces magnet costs, and relieves bearing stress by minimizing attractive forces, enabling flexible adaptation and high torque capabilities while maintaining efficient operation.

Implementation Method 1

A first active segment (7) of each segment pair (3) has several electromagnets (13) arranged one behind the other along the arc

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

A second active segment (9) of each segment pair (3) has several permanent magnets (21) arranged one behind the other along the arc

Methodology Applied
Scientific EffectMagnetism: Magnetism

Implementation Method 3

The rotor (4) has an annular reaction element (5) extending along a reaction element circle (11) around the axis of rotation and comprising several magnetizable regions (25) arranged one after the other along the reaction element circle

Methodology Applied
Scientific EffectLorentz force: Lorentz Force

Data Source

PatentEP3679641B1Rotating electric machine
Publication Date: 2021.09.01 SIEMENS AG
  • EP3679641B1 patent drawingFigure 1
  • EP3679641B1 patent drawingFigure 2
  • EP3679641B1 patent drawingFigure 3

AI summary

The invention relates to a rotating electric machine (1) having a stator (2) and a rotor (4), which is rotatable about a rotation axis (6) relative to the stator (2). The rotor (4) has an annular reaction element (5), which extends along a reaction element circle (11) about the rotation axis (6) and has a plurality of magnetizable regions (25) arranged one behind the other along the reaction element circle (11), wherein a non-magnetic region (23) is arranged between every two adjacent magnetizable regions (25). The stator (2) has at least one segment pair (3) comprising two active sub-segments (7, 9), between which a circular arc of the reaction element circle (11) extends, wherein a first active sub-segment (7) of each segment pair (3) has a plurality of electromagnets (13) arranged one behind the other along the course of the circular arc and the second active sub-segment (9) of the segment pair (3) has a plurality of permanent magnets (21) arranged along the course of the circular arc.