Grain-Oriented Stator Teeth for Compact Vehicle PM Generators

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Solution Overview

Problem

Existing generators for on-board vehicle charging face a challenge in achieving high specific power and efficiency while maintaining a good performance-to-price ratio, due to the anisotropic magnetic characteristics of grain-oriented iron-silicon alloys and the need for smaller generator dimensions.

Innovation Solution

A permanent magnet generator design using a stator yoke made of non-oriented magnetic steel and stator teeth made of grain-oriented magnetic steel, with a dovetail interlocking system and high-temperature resistant plastic coating, to optimize magnetic flux directionality and reduce leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If grain-oriented steel sheets are used in stator teeth, then magnetic characteristics along rolling direction are improved, but manufacturing complexity increases due to orientation requirements

Engineering Contradiction:

Improvemagnetic characteristicsVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The stator is divided into two distinct parts: a yoke made of non-oriented steel sheets and teeth made of grain-oriented steel sheets. This segmentation allows each part to be optimized independently - the yoke provides general magnetic path support while the teeth provide optimized magnetic characteristics along the rolling direction where flux passes through them radially.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the stator are assigned different material properties: the yoke uses non-oriented steel with isotropic magnetic properties suitable for general structural support, while the teeth use grain-oriented steel with superior magnetic properties along the rolling direction, precisely where the magnetic flux needs optimization.

Inventive Principle:

Principle #3Local quality

2Reliability

If cobalt-based alloys are used, then magnetic and leakage characteristics are improved, but cost increases significantly

Engineering Contradiction:

Improvemagnetic characteristicsVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention changes the material parameter selection from high-performance but expensive cobalt-based alloys to a hybrid steel system. By carefully selecting grain-oriented steel for teeth and non-oriented steel for the yoke, the system achieves comparable magnetic characteristics at a fraction of the cost, making the solution economically viable for mass production.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces expensive cobalt-based alloys with more economical steel-based materials. While steel has different magnetic properties, the hybrid configuration of grain-oriented and non-oriented sheets achieves sufficient performance for vehicle applications at a much lower cost, making the generator economically feasible for the target market.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Volume of moving object

If generator size is reduced for on-board vehicle space constraints, then space utilization is improved, but achieving high specific power becomes more difficult

Engineering Contradiction:

Improvegenerator sizeVSAvoidspecific power

Core Design Contradiction:

Volume of moving objectVSPower

Solution Approach 1:

The stator employs a composite structure combining grain-oriented and non-oriented steel sheets in specific configurations. This composite approach maximizes magnetic flux density and reduces leakage within the limited space available, thereby achieving high specific power output from a compact generator design suitable for on-board vehicle installation.

Inventive Principle:

Principle #40Composite materials

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 achieves higher current output at lower speeds with the same mechanical size, improved electrical performance, and cost-effectiveness, while allowing for flexible manufacturing processes.

Implementation Method 1

grain-oriented magnetic steel sheets have anisotropic magnetic characteristics, i.e., good magnetic characteristics of both permeability and saturation induction along the rolling direction

Methodology Applied

Scientific EffectMagnetic flux conduction: Magnetic Field

Implementation Method 2

grain-oriented magnetic steel sheets have anisotropic magnetic characteristics

Methodology Applied

Scientific EffectMagnetic anisotropy: Anisotropy

Implementation Method 3

permanent magnet generator for on-board vehicle charging

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS12597828B2Permanent magnet generator with stator teeth made of sheets with oriented grains for on-board vehicle charging

Publication Date: 2026.04.07 DUCATI ENERGIA

AI summary

A permanent magnet generator for on-board vehicle charging comprises an external rotor, a stator assembly accommodated inside the external rotor and provided with a stator yoke, with a plurality of stator teeth extending from the stator yoke and with a plurality of conductive windings arranged around each of said stator teeth, a permanent magnet associated with a portion of an internal wall of the external rotor and facing the stator assembly, wherein the stator yoke is made of magnetic steel sheet with non-oriented grains and the stator teeth are made of magnetic steel sheet with oriented grains.