Superconducting Field Coil Support Structure for Stable Magnetic Gap

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Solution Overview

Problem

Superconducting generators experience performance degradation due to increased magnetic gap between field coils and armature winding coils caused by thermal shrinkage during cooldown, which affects efficiency and torque production, especially in high-power applications like wind turbines and ship propulsion systems.

Innovation Solution

An annular field winding assembly with a field coil support structure made of low thermal expansion materials, such as nickel-cobalt ferrous alloys or composite materials, is used to maintain a consistent magnetic gap by minimizing shrinkage, and the superconducting coils are cooled using vaporized cryogenic liquids to achieve a superconducting state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If aluminum field coil former structure is used, then ease of manufacture is improved, but magnetic gap increases due to thermal shrinkage during cooldown

Engineering Contradiction:

Improveease of manufactureVSAvoidmagnetic gap

Core Design Contradiction:

Ease of manufactureVSLength of stationary object

Solution Approach 1:

The patent changes the material parameter (coefficient of thermal expansion) of the field coil former from aluminum (high expansion) to low thermal expansion materials such as Invar, Kovar, or composite materials. This parameter change ensures the former maintains its dimensional stability during the cooldown process, preventing magnetic gap increase while remaining manufacturable.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials, specifically carbon fiber reinforced polymers (CFRP) or glass fiber reinforced polymers (GFRP), as field coil former materials. These composite materials provide both the required mechanical strength and low thermal expansion properties to maintain magnetic gap stability during cooldown, while being manufacturable using modern composite fabrication techniques.

Inventive Principle:

Principle #40Composite materials

2Strength

If superconducting material is used for field coils, then magnetic field strength is improved, but thermal shrinkage during cooldown worsens the magnetic gap

Engineering Contradiction:

Improvemagnetic field strengthVSAvoidmagnetic gap

Core Design Contradiction:

StrengthVSLength of stationary object

Solution Approach 1:

The patent addresses the thermal shrinkage issue by changing the thermal expansion parameter of the support structure material. By selecting materials with coefficients of thermal expansion matched to the superconducting coils or with very low expansion values, the structure maintains dimensional stability during the extreme temperature transition, preserving the magnetic gap while enabling the use of high-field-strength superconducting materials.

Inventive Principle:

Principle #35Parameter changes

3Power

If large radii field coil former structure is used, then generator power output is improved, but radial shrinkage during cooldown increases magnetic gap

Engineering Contradiction:

Improvepower outputVSAvoidmagnetic gap

Core Design Contradiction:

PowerVSLength of stationary object

Solution Approach 1:

The patent solves the problem by changing the material parameter (thermal expansion coefficient) of the field coil former. Low thermal expansion materials or composites with tailored thermal properties are used to ensure that even large-radius structures maintain their dimensional stability during cooldown, preventing magnetic gap increase while enabling high power output through larger generator design.

Inventive Principle:

Principle #35Parameter changes

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 maintains a stable magnetic gap, enhancing torque density and efficiency, allowing for high-power generation (10-35 MW) while reducing material costs and maintaining a compact, lightweight design, thus addressing the performance degradation issue.

Implementation Method 1

cooling the plurality of superconducting coils to a superconducting condition using a cooling liquid that is at least partially vaporized as it cools the plurality of superconducting coils

Methodology Applied

Scientific EffectVaporization: Evaporation

Implementation Method 2

Each of the plurality of superconducting coils disposed in a recess of the annular array of recesses. The field coil support structure is comprised of a material having a low coefficient of thermal expansion to maintain a dimension of the gap between the non-rotating annular field winding assembly and the armature assembly during cooling of the plurality of superconducting coils to the superconducting condition

Methodology Applied

Scientific EffectSuperconductivity: Superconductivity

Data Source

PatentUS12149149B2Field coil support structure and modular field coil design in a superconducting machine

Publication Date: 2024.11.19 GENERAL ELECTRIC RENOVABLES ESPANA SL

AI summary

An electric machine including an annular armature assembly and a non-rotating annular field winding assembly coaxial with the armature assembly and separated by a gap from the armature assembly. The field winding assembly including a field coil support structure having an annular array of recesses formed therein and extending about the field coil support structure. The field winding assembly further including a plurality of superconducting coils, each disposed in a recess of the annular array of recesses. A generator and a method for generating electrical power are disclosed.