Transformer Secondary Coil Curvature for Dielectric Breakdown Control

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Solution Overview

Problem

Power converters with transformers face challenges in achieving improved dielectric breakdown voltage and power efficiency, particularly due to high electric field concentrations that can lead to dielectric breakdown and increased power losses.

Innovation Solution

The transformer design includes a first core, primary coil, secondary coil, and insulating member, where the secondary coil is subjected to high voltage and features a polygonal shape with a corner radius of 0.1 mm or more, reducing electric field concentration and allowing for miniaturization of the core, thereby enhancing dielectric breakdown voltage and power efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the secondary coil has sharp corners (small radius of curvature), then the coil structure is simpler and easier to manufacture, but electric field concentration increases leading to dielectric breakdown of the insulating member

Engineering Contradiction:
Improvedielectric breakdown voltageVSAvoidcoil corner processing
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies curvature to the corners of the secondary coil conductor by specifying that each corner has a radius of curvature of 0.1 mm or more. This rounded corner design eliminates sharp edges that would concentrate electric fields, thereby preventing dielectric breakdown of the insulating member while maintaining manufacturability through standard bending processes.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Volume of moving object

If the transformer core is miniaturized, then the overall device size is reduced, but electric field concentration may increase affecting dielectric breakdown voltage

Engineering Contradiction:
Improvetransformer sizeVSAvoiddielectric breakdown voltage
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

By rounding the corners of the secondary coil with a radius of 0.1 mm or more, the patent eliminates electric field concentration points that would be particularly problematic in miniaturized transformers. This allows the transformer to be compact while maintaining high dielectric breakdown voltage through the curved corner geometry that distributes electric fields evenly.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Reliability

If the corner radius of the secondary coil is increased, then dielectric breakdown voltage is improved, but the coil and core size increase

Engineering Contradiction:
Improvedielectric breakdown voltageVSAvoidtransformer size
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The patent optimizes the corner radius parameter to 0.1 mm or more, which is sufficient to eliminate electric field concentration and prevent dielectric breakdown without causing excessive increase in coil or transformer size. This parameter selection balances reliability improvement with compact dimensions.

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

This design effectively restrains dielectric breakdown and miniaturizes the transformer, leading to improved power efficiency and reduced power losses, even at high voltages, by managing electric field strength and leveraging low-power-loss magnetic materials.

Implementation Method 1

an increase in electric field strength, which results from the concentration of electric field at the first corner, can be restrained

Methodology Applied
Scientific EffectElectric field concentration: Electric Field

Implementation Method 2

a power converter comprising a transformer... including a first core, a first primary coil, a first secondary coil

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3706150B1Power converter comprising a transformer
Publication Date: 2023.09.20 MITSUBISHI ELECTRIC CORP
  • EP3706150B1 patent drawingFigure 1
  • EP3706150B1 patent drawingFigure 2~3
  • EP3706150B1 patent drawingFigure 4~5

AI summary

A transformer (1) includes a first core (13), a first primary coil (11), a first secondary coil (12), and a first insulating member (15). The first secondary coil (12) includes a second conductor (17) wound around the first core (13). The first insulating member (15) covers the first secondary coil (12). The second conductor (17) has a shape of a first polygon in a cross-section of the second conductor (17). A first corner (17p) of the first polygon has a first radius of curvature of 0.1 mm or more. The transformer (1) thus has improved dielectric breakdown voltage and improved power efficiency.