Transformer Core Chamfered Corners Reduce Electric Field Concentration

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Solution Overview

Problem

Conventional transformers designed for high-voltage applications in facilities like data centers face challenges in achieving both size reduction and high dielectric strength due to electric field concentration at the core's corner parts, which compromises the secure distance between windings and core, leading to potential partial discharge.

Innovation Solution

The transformer incorporates a core with chamfered corner parts into curved surface shapes, along with resin-sealed primary windings and edgewise wound secondary metal plates, allowing for a compact design while enhancing dielectric strength by reducing electric field concentration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the distance between primary winding and core corner part is reduced to achieve size reduction, then the transformer size is reduced, but dielectric strength decreases due to electric field concentration at corner parts

Engineering Contradiction:

Improvetransformer sizeVSAvoiddielectric strength

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The corner parts of the core are chamfered into curved surface shapes with a radius of curvature of 0.5 mm or more. This curvature modification eliminates sharp corners that concentrate electric fields, thereby suppressing partial discharge while maintaining the reduced transformer size. The curved surfaces distribute the electric field more evenly, preventing dielectric breakdown even at close distances between windings and core.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Reliability

If resin sealing is applied to primary windings, then dielectric strength is enhanced, but manufacturing complexity increases

Engineering Contradiction:

Improvedielectric strengthVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The primary windings are sealed with resin to form an integrated structure with the core. This resin sealing creates a protective barrier that enhances dielectric strength and prevents partial discharge, while the integration of windings and core into a single molded structure simplifies assembly and manufacturing processes.

Inventive Principle:

Principle #30Flexible shells and thin films

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

This configuration effectively increases the partial discharge inception voltage, ensuring high dielectric strength and size reduction, making it suitable for mounting on printed circuit boards while maintaining performance under high input voltages.

Implementation Method 1

electric field concentration that easily occurs at the corner part of the core

Methodology Applied

Scientific EffectElectric field concentration: Electric Field

Implementation Method 2

resin sealing after parts other than a core are contained in a synthetic resin case

Methodology Applied

Scientific EffectDielectric insulation: Dielectric

Implementation Method 3

a transformer that has a high withstand voltage against a relatively high voltage of several kV or more to output DC power of a relatively low predetermined voltage

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10923271B2Core and transformer

Publication Date: 2021.02.16 FUJI ELECTRIC CO LTD

AI summary

A core is provided that includes a corner part facing a winding wound on a shaft part, the corner part being chamfered into a curved surface shape.