Magnetic Core Cooling with Non-Magnetic Master Sheet

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Solution Overview

Problem

Iron inductors in high-speed motors experience significant iron losses and conduction losses due to high-frequency currents, leading to increased size and energy dissipation, while air inductors are bulky and prone to radiation and eddy currents.

Innovation Solution

A magnetic core for induction coils comprising bundles of magnetic material with air gaps and tie rods, where a heat-conducting non-magnetic master sheet acts as a heat collector and radiator, with cooling tubes connected to a fluid circulation circuit to manage temperature and reduce losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If iron core is used in inductors for high-speed motors, then magnetic flux is better channeled and inductor size is reduced, but iron losses increase rapidly with frequency

Engineering Contradiction:
Improveinductor sizeVSAvoidiron losses
Core Design Contradiction:
Volume of moving objectVSLoss of energy

Solution Approach 1:

The iron core is segmented into multiple bundles of sheets separated by air gaps. This segmentation reduces the continuous magnetic path, limiting the magnetic field strength and thereby reducing iron losses (hysteresis and eddy currents) while maintaining compact inductor dimensions through the concentrated flux paths in each bundle.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the physical parameters of the core by introducing air gaps between bundles of sheets. This modifies the magnetic circuit properties, reducing the effective permeability and limiting the magnetic field, which directly reduces iron losses at high frequencies while maintaining acceptable inductance through increased winding turns.

Inventive Principle:
Principle #35Parameter changes

2Loss of energy

If air gaps are added to limit magnetic field and reduce iron losses, then energy losses decrease, but number of windings and iron section must be increased

Engineering Contradiction:
Improveiron lossesVSAvoidnumber of windings and iron section
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The core is divided into multiple bundles of sheets with air gaps between them. This segmentation allows the magnetic field to be confined within each bundle, reducing the overall field strength and iron losses. The segmented structure achieves loss reduction without requiring a proportional increase in total iron section, as each bundle operates independently with lower flux density.

Inventive Principle:
Principle #1Segmentation

3Loss of energy

If inductor section is increased to handle high-frequency currents, then conduction losses are managed, but inductor dimensions become very large

Engineering Contradiction:
Improveconduction lossesVSAvoidinductor dimensions
Core Design Contradiction:
Loss of energyVSVolume of moving object

Solution Approach 1:

The segmented core structure with multiple bundles of sheets separated by air gaps creates multiple parallel magnetic paths. This allows the inductor to handle high-frequency currents more efficiently by distributing the flux, reducing conduction losses without requiring a large single continuous iron section, thereby maintaining compact overall dimensions.

Inventive Principle:
Principle #1Segmentation

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 effectively mitigates iron and conduction losses by efficiently cooling the magnetic core, maintaining proper functioning and reducing the size and energy dissipation of the inductors.

Implementation Method 1

The master sheet, in addition to its traditional function of mechanical support, acts as a heat collector and radiator, the fluid circulating in the cooling tubes carrying the calories collected by the master sheet

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the fluid circulating in the cooling tubes carrying the calories collected by the master sheet and ensuring the temperature maintenance of the magnetic core

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP1993111B1Cooling of the magnetic core of an induction coil.
Publication Date: 2010.02.17 CONVERTEAM TECH LTD
  • EP1993111B1 patent drawingFigure 1
  • EP1993111B1 patent drawingFigure 2

AI summary

The core has link sticks traversing packets of sheets perpendicular to an axis (6) for assuring connection of the sheets of each packet. A main sheet (12) is plated by the link sticks parallel to the sheets for assuring the connection of core elements, where the main sheet is made of non-magnetic heat conducting material i.e. aluminum. A cooling tube (15) is welded on the main sheet, and a connector (16) connects the cooling tube with a coolant circulation circuit (17).