Fractional-slot Winding Electric Machine for Cost Reduction

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Solution Overview

Problem

High-cost and complex manufacturing of internal permanent magnet (IPM) electric machines limits the commercialization of hybrid-electric and electric vehicles due to expensive magnet requirements, intricate designs, and high-speed operational challenges, making them cost-prohibitive for widespread adoption.

Innovation Solution

A synchronous reluctance electric machine with a fractional-slot concentrated winding configuration, utilizing two sets of terminals to achieve AC and DC excitations for different pole numbers, eliminating the need for permanent magnets and simplifying the rotor and stator designs, thereby reducing manufacturing complexity and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If internal permanent magnet (IPM) machines are used to achieve high power density and high efficiency, then power density and efficiency are improved, but manufacturing cost increases due to expensive sintered magnets

Engineering Contradiction:

Improvepower densityVSAvoidmanufacturing cost

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The patent extracts and removes the permanent magnets from the electric machine design, transitioning from an IPM machine to a permanent magnet-free machine. This eliminates the need for expensive sintered magnets while maintaining high power density through alternative magnetic circuit design and winding configurations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces expensive permanent magnets with cheaper alternative components (windings and magnetic circuits) that can achieve similar performance. The design uses conventional materials and manufacturing processes instead of costly sintered magnets, making the machine more cost-effective.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Power

If IPM machines operate at high speed (e.g., 14,000 rpm) to obtain optimum power density, then power density is improved, but system cost increases due to high back EMF requiring high voltage inverter devices

Engineering Contradiction:

Improvepower densityVSAvoidsystem cost

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The patent changes the electrical parameters of the machine design, specifically the winding configuration and pole structure, to reduce back EMF generation. This allows the machine to operate at high speeds with lower voltage requirements, eliminating the need for expensive high-voltage inverter devices.

Inventive Principle:

Principle #35Parameter changes

3Power

If IPM machines use intricate rotor and stator designs for higher slot fill, then power density is improved, but device complexity increases

Engineering Contradiction:

Improvepower densityVSAvoiddesign complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent segments the winding structure into concentrated windings with specific connection patterns that simplify the overall design. The rotor and stator are designed with simpler geometries that are easier to manufacture while maintaining effective magnetic coupling and high power density.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of using complex distributed windings that require intricate rotor-stator designs, the patent inverts the approach by using concentrated windings with simplified connection topologies. This reversal of the conventional design philosophy reduces complexity while achieving comparable or superior performance.

Inventive Principle:

Principle #13The other way round (Inversion)

4Power

If IPM machines use small air gap (e.g., 0.51 - 0.76mm) to achieve high power density, then power density is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvepower densityVSAvoidair gap tolerance

Core Design Contradiction:

PowerVSManufacturing precision

Solution Approach 1:

The patent combines multiple design features (winding configuration, pole structure, and magnetic circuit design) to achieve high power density without relying on a small air gap. This integration of multiple parameters allows for a larger, more tolerant air gap while maintaining performance.

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

The solution enables high power-density and high-efficiency electric machines with reduced manufacturing costs, improved reliability, and suitability for high-speed applications without the need for high-voltage inverters, making them more viable for electric and hybrid-electric vehicle traction.

Implementation Method 1

a first set of terminals configures the fractional-slot concentrated winding to have a first pole-number (P1), and wherein a second set of terminals configures the fractional-slot concentrated winding to have a second pole number (P2) different from the first pole-number (P1)

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2410639B1High power-density, high efficiency, non-permanent magnet electric machine

Publication Date: 2014.06.11 GENERAL ELECTRIC CO

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AI summary

A system and method of manufacturing an electric machine comprising a rotor and a stator, wherein the stator comprises a fractional-slot concentrated winding having two sets of terminals, wherein a first set of terminals configures the fractional-slot concentrated winding to have a first pole-number (P1), and wherein a second set of terminals configures the fractional-slot concentrated winding to have a second pole number (P2) different from the first pole-number (P1).