Claw-pole Rotor Winding Design for Slot Fill and Noise

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Solution Overview

Problem

Existing electrical machines with claw-pole rotors face challenges in maximizing slot area and reducing slot spread while maintaining low production costs and minimizing noise and insulation damage.

Innovation Solution

A five-phase electrically excited claw-pole machine with a sixteen-pole rotor and a stator core made from pre-stamped sheet metal, featuring a distributed wave winding design that increases slot fill factor and reduces yoke height, thereby enhancing output power and noise reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a simple wave winding is used, then the winding can be produced at low cost, but the slot fill factor is low and the pull-in force is high

Engineering Contradiction:
Improvewinding production costVSAvoidslot fill factor
Core Design Contradiction:
Ease of manufactureVSQuantity of substance

Solution Approach 1:

The patent changes the winding configuration from simple wave winding to distributed wave winding with multiple strands (5 strands), which modifies the winding parameters to achieve higher slot fill factor while maintaining low production cost through the pull-in winding method

Inventive Principle:
Principle #35Parameter changes

2Strength

If the yoke height is increased, then the structural strength is improved, but the slot depth is reduced and slot area is reduced

Engineering Contradiction:
Improveyoke strengthVSAvoidslot area
Core Design Contradiction:
StrengthVSArea of stationary object

Solution Approach 1:

The patent optimizes the yoke height parameter to achieve the best compromise between structural strength and slot area, using a specific yoke height range that allows sufficient mechanical strength while maximizing the available slot area for winding placement

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If the slot spread is increased, then the winding insertion is facilitated, but the slot area is reduced and magnetic performance deteriorates

Engineering Contradiction:
Improvewinding insertion easeVSAvoidslot area
Core Design Contradiction:
Ease of operationVSArea of stationary object

Solution Approach 1:

The patent optimizes the slot spread parameter within a specific range that balances the ease of winding insertion with the preservation of sufficient slot area, achieving both manufacturability and magnetic performance

Inventive Principle:
Principle #35Parameter changes

4Device complexity

If conventional winding methods are used, then the production process is simple, but the winding insulation is at risk of damage

Engineering Contradiction:
Improvewinding process complexityVSAvoidinsulation integrity
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent employs a pull-in winding method where the winding is inserted into the slots in a controlled manner, with preliminary positioning and guiding structures that prevent insulation damage during the winding insertion process

Inventive Principle:
Principle #10Preliminary action

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 increases slot area and output power, reduces noise, and simplifies winding insulation protection, achieving a high slot fill factor at low costs without risking insulation damage.

Implementation Method 1

an electrically excited claw-pole machine with a sixteen-pole rotor and a stator core made from pre-stamped sheet metal, featuring a distributed wave winding design

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2374198B1Electric machine having a claw-pole rotor
Publication Date: 2012.09.26 ROBERT BOSCH GMBH
  • EP2374198B1 patent drawingFigure 1
  • EP2374198B1 patent drawingFigure 2
  • EP2374198B1 patent drawingFigure 3

AI summary

The invention relates to an electric machine comprising a claw-pole rotor, particularly an electrically excited, at least 12-pole claw-pole machine (10) for a motor vehicle. The stator (16) of the machine, the winding of which has multiple phase windings and is connected to a rectifier arrangement (69) or alternatively to a pulse-controlled inverter arrangement using the phase winding connections (80 to 84) of said winding, has an inner diameter (Di) that is smaller than the associated outer diameter (Da) of the machine by a factor of 0.70 to 0.77, preferably by a factor of 0.73 to 0.75, at least in the groove center. According to the invention, the ratio of the groove widths (Bn2) at the groove openings (37) to the groove widths (Bn1) at the respective groove base (36) lies in the range of 0.69 to 0.81, preferably in the range of 0.73 to 0.78.