Integrated Transformer Coupled Inductor Magnetic Core Design

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Solution Overview

Problem

Conventional integrated magnetic devices in switching power converters face issues with magnetic saturation, especially when powering high-frequency transient loads, and generate significant fringing magnetic flux and electromagnetic interference, making them difficult to manufacture and inefficient.

Innovation Solution

The development of integrated transformers and coupled inductors with a magnetic core configuration that includes separated rails, rungs, and a leakage plate, optimized for strong coupling and minimal fringing flux, along with secondary-side current mode control to prevent magnetic saturation, results in a compact, efficient, and easily manufacturable design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of stationary object

If conventional integrated magnetic devices are used in switching power converters, then the converter size is reduced, but magnetic saturation occurs especially when powering high-frequency transient loads

Engineering Contradiction:

Improveconverter sizeVSAvoidmagnetic saturation resistance

Core Design Contradiction:

Volume of stationary objectVSReliability

Solution Approach 1:

The magnetic core is segmented into separate rails and rungs that form distinct magnetic paths for different windings. This segmentation prevents flux imbalances from causing saturation by providing independent magnetic circuits for each winding combination, while still achieving integration in a single package.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the magnetic core are optimized for different functions: some regions provide strong coupling between specific windings, while other regions provide leakage inductance. This local optimization allows each winding pair to operate independently without interfering with others, preventing saturation.

Inventive Principle:

Principle #3Local quality

2Device complexity

If conventional integrated magnetic devices are used, then multiple discrete inductors are replaced, but significant fringing magnetic flux and electromagnetic interference are generated

Engineering Contradiction:

Improvenumber of discrete componentsVSAvoidfringing magnetic flux and electromagnetic interference

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent intentionally introduces leakage plates that create controlled leakage inductance, converting what would normally be harmful fringing flux into useful energy storage. This controlled leakage flux is contained within the magnetic core structure and used for soft-switching purposes, eliminating EMI while maintaining the benefits of integration.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If conventional integrated magnetic devices are used, then converter performance is improved, but manufacturing difficulty increases

Engineering Contradiction:

Improveconverter performanceVSAvoidmanufacturing difficulty

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

Multiple magnetic components (transformer and coupled inductors) are merged into a single integrated package with a unified magnetic core structure. The core consists of rails and rungs that can be manufactured as a single piece or pre-assembled module, simplifying the manufacturing process while achieving the performance benefits of multiple integrated components.

Inventive Principle:

Principle #5Merging (Combining)

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 reduces magnetic saturation, minimizes fringing flux, and enhances manufacturing ease, leading to improved efficiency and performance in switching power converters, particularly when handling transient loads.

Implementation Method 1

a magnetic core configuration that includes separated rails, rungs, and a leakage plate, optimized for strong coupling and minimal fringing flux

Methodology Applied

Scientific EffectMagnetic flux confinement: Magnetic Field

Implementation Method 2

integrated transformers and coupled inductors... first primary winding, a second primary winding, a first secondary winding, and a second secondary winding

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10297379B2Integrated transformers and coupled inductors and associated systems and methods

Publication Date: 2019.05.21 MAXIM INTEGRATED PROD INC

AI summary

A switching power converter includes an integrated transformer and coupled inductor, first and second primary switching circuits, and a master controller. The integrated transformer and coupled inductor includes (a) first and second primary windings electrically coupled in series and (b) first and second secondary windings. The first and second primary switching circuits are electrically coupled to an end of the first primary winding and an end of the second primary winding, respectively. The master controller is configured to determine a magnitude of magnetizing current of the integrated transformer and coupled inductor from a difference between magnitude of current flowing through the first secondary winding and magnitude of current flowing through the second secondary winding, when the first and second primary switching circuits are in their respective off-states.