Integrated Transformer Current Doubler for High Step-Down Converters

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Solution Overview

Problem

LLC resonant converters are not suitable for applications requiring wide voltage ranges and fast transient responses, such as 48V to 1V DC-to-DC voltage converters, due to their inefficiencies and reduced power density.

Innovation Solution

The integration of a switched bridged input stage with a current doubler rectifier output stage using an integrated transformer that includes magnetic cores with primary and secondary windings, and a coupling winding for magnetic integration, eliminating the need for separate inductors and reducing leakage inductance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If LLC resonant converter is used to achieve high step-down voltage ratios, then voltage conversion capability is improved, but power density and transient response are worsened

Engineering Contradiction:

Improvepower densityVSAvoidtransient response

Core Design Contradiction:

PowerVSAdaptability or versatility

Solution Approach 1:

The patent combines the transformer and inductors into a single integrated transformer component. The integrated transformer includes a primary winding, secondary winding, and tertiary winding wound around a common magnetic core, eliminating the need for separate inductor components. This merging of components increases power density by reducing the overall component footprint while maintaining the necessary magnetic coupling for high step-down voltage ratios and fast transient response.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated transformer serves multiple functions simultaneously: it provides voltage transformation through the primary and secondary windings, and it provides inductance through the tertiary winding that couples to the current doubler rectifier. This multi-functionality allows a single component to replace what would traditionally require separate transformer and inductor components, improving power density without sacrificing transient response capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Device complexity

If separate inductors are used in current doubler rectifier output stage, then inductance function is achieved, but device complexity and power loss are worsened

Engineering Contradiction:

Improvecomponent integrationVSAvoidpower loss

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent merges the inductor function into the integrated transformer by adding a tertiary winding that couples magnetically to the primary and secondary windings. This eliminates the need for separate inductor components, reducing device complexity and the number of interconnections. The magnetic coupling within the integrated transformer reduces leakage inductance and associated power losses compared to discrete inductor connections.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent converts what would traditionally be harmful leakage inductance in separate inductor connections into beneficial tightly-coupled magnetic fields within the integrated transformer. The shared magnetic core and closely-wound windings create strong magnetic coupling that minimizes leakage, transforming the potential source of power loss into an efficiency improvement.

Inventive Principle:

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

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 solution improves power density and efficiency while maintaining fast transient responses, reducing costs and power loss compared to traditional designs with separate transformers and inductors.

Implementation Method 1

an integrated transformer with magnetic cores. A primary winding and a secondary winding of the integrated transformer extend around each of the plurality of magnetic cores, and the integrated transformer further includes a coupling winding that extends around each of the plurality of magnetic cores to provide magnetic integration among the plurality of magnetic cores through an electrical coupling

Methodology Applied

Scientific EffectMagnetic coupling: Electromagnetic Induction

Implementation Method 2

The current doubler rectifier output stage relies upon magnetizing inductance of the integrated transformer to realize the function of inductors

Methodology Applied

Scientific EffectMagnetizing inductance: Electromagnetic Induction

Data Source

PatentUS20230396180A1Integrated transformers for high current converters

Publication Date: 2023.12.07 VIRGINIA TECH INTELLECTUAL PROPERTIES INC

AI summary

Power converters with current doubler rectifier output stages, current doubler rectifier output stages, and integrated transformers for current doubler rectifier output stages and related output stages are described. In one example, a power converter includes a switched bridged input stage and a current doubler rectifier output stage comprising an integrated transformer. The integrated transformer of the current doubler rectifier output stage includes magnetic cores. A primary winding and a secondary winding of the integrated transformer extend around each of the plurality of magnetic cores, and the integrated transformer further includes a coupling winding that extends around each of the plurality of magnetic cores to provide magnetic integration among the plurality of magnetic cores through an electrical coupling. The current doubler rectifier output stage relies upon magnetizing inductance of the integrated transformer to realize the function of inductors, and the integrated transformer current doubler rectifier does not include separate inductors.