Isolation Transformer Magnetic Shield Plate

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Solution Overview

Problem

The challenge is to reduce the size of an isolation transformer in power conversion devices while minimizing the increase in winding resistance and loss due to higher switching frequencies, which typically leads to increased size and temperature issues.

Innovation Solution

Incorporating a magnetic shield portion between the primary and secondary windings to suppress magnetic interference, thereby reducing the resistance value and winding loss, and using a configuration that allows for efficient cooling to maintain compactness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If switching frequency is increased to reduce isolation transformer size, then core size and iron loss are reduced, but winding resistance and copper loss increase due to skin effect and proximity effect

Engineering Contradiction:

Improveisolation transformer sizeVSAvoidwinding loss

Core Design Contradiction:

Volume of moving objectVSLoss of energy

Solution Approach 1:

A magnetic shield plate is introduced as an intermediary component between the primary and secondary windings. This magnetic shield plate interrupts the magnetic flux generated by currents in the windings, suppressing proximity effect and reducing winding resistance. The magnetic shield plate acts as a mediator that blocks harmful magnetic interference while allowing the high switching frequency operation to continue, thus resolving the contradiction between reduced transformer size and increased winding loss.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Volume of moving object

If switching frequency is increased to reduce isolation transformer size, then voltage-time product is reduced, but temperature of winding increases due to increased copper loss

Engineering Contradiction:

Improveisolation transformer sizeVSAvoidwinding temperature

Core Design Contradiction:

Volume of moving objectVSTemperature

Solution Approach 1:

The magnetic shield plate serves as a thermal management intermediary by suppressing proximity effect and reducing copper loss, thereby preventing excessive temperature rise in the windings. By interrupting the magnetic flux, the magnetic shield plate reduces the energy loss that would otherwise convert to heat, allowing the isolation transformer to maintain compact size at high switching frequencies without overheating.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Loss of energy

If cross sectional area of winding is increased to reduce winding loss, then copper loss decreases, but isolation transformer becomes large-sized

Engineering Contradiction:

Improvewinding lossVSAvoidisolation transformer size

Core Design Contradiction:

Loss of energyVSVolume of moving object

Solution Approach 1:

The magnetic shield plate introduces a new approach by inserting a magnetic shielding component between the windings. This intermediary structure suppresses proximity effect and reduces winding resistance without requiring increased conductor cross-sectional area. The magnetic shield plate allows the use of smaller windings while maintaining low copper loss, thus resolving the contradiction between reduced winding loss and compact transformer size.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enables a reduction in the size of the isolation transformer while maintaining efficiency and preventing overheating, resulting in a compact and high-performance power conversion device.

Implementation Method 1

a magnetic shield portion configured to suppress magnetic interference between the primary winding and the secondary winding by interrupting a magnetic flux generated by a current flowing through each of the primary winding and the secondary winding

Methodology Applied

Scientific EffectMagnetic flux interruption: Magnetic Field

Implementation Method 2

The isolation transformer includes: a core (also referred to as 'transformer core') mainly composed of iron; and a primary winding and a secondary winding wound around the core

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS11424071B2Power conversion device

Publication Date: 2022.08.23 MITSUBISHI ELECTRIC CORP

AI summary

A power conversion device includes an isolation transformer, the isolation transformer including: a primary winding; a secondary winding; and a magnetic shield portion configured to suppress magnetic interference between the primary winding and the secondary winding by interrupting a magnetic flux generated by a current flowing through each of the primary winding and the secondary winding. The magnetic shield portion is formed of, for example, a magnetic shield plate arranged between the primary winding and the secondary winding.