LLC Converter Magnetic Core Winding Layout for Lower Winding Loss

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Solution Overview

Problem

Existing LLC resonant converters face limitations in high-current, low-voltage applications due to high winding losses and reduced flexibility, as known integrated transformers require litz wire and adjust stray inductance, leading to increased fringing fields and inefficiencies.

Innovation Solution

A converter component with a magnetic core having three legs, where the second electrical winding is wound around the first and second legs to form integrated resonant and magnetizing inductances, increasing application flexibility and reducing winding losses by avoiding electrical connection between windings and using a U-shaped or ring-shaped winding configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If litz wire is used for primary and secondary windings in integrated transformers, then winding losses are reduced, but the degree of flexibility for usage scenarios decreases and litz wire is not applicable in high-current low-voltage applications

Engineering Contradiction:
Improvewinding lossesVSAvoiddegree of flexibility for usage scenarios
Core Design Contradiction:
Loss of energyVSAdaptability or versatility

Solution Approach 1:

The patent changes the wire type parameter from litz wire to round wire, and adjusts the winding configuration parameter to achieve low winding losses suitable for high-current applications. This parameter change enables the transformer to be adaptable to high-current low-voltage scenarios where litz wire would be inapplicable.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If magnetic shunt is placed between primary and secondary windings to adjust stray inductance, then stray inductance is adjusted, but fringing field increases and winding losses increase

Engineering Contradiction:
Improvestray inductance adjustmentVSAvoidwinding losses
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent extracts and removes the magnetic shunt component from between the windings, eliminating the fringing field problem. Instead, stray inductance is adjusted through winding configuration parameters, achieving the desired stray inductance adjustment without the harmful fringing field that would increase winding losses.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If separate magnetic components are used for resonant inductance, magnetizing inductance, and transformer, then each component can be optimized independently, but device complexity increases

Engineering Contradiction:
Improvecomponent optimizationVSAvoidnumber of magnetic components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the resonant inductance, magnetizing inductance, and transformer into a single integrated magnetic component. The primary winding forms the transformer primary and resonant inductance, while the secondary winding forms the transformer secondary and magnetizing inductance. This merging reduces device complexity while maintaining the ability to optimize each function through winding parameter adjustment.

Inventive Principle:
Principle #5Merging (Combining)

4Power

If integrated transformer is designed for high-current applications, then current handling capability increases, but winding losses increase due to fringing field

Engineering Contradiction:
Improvecurrent handling capabilityVSAvoidwinding losses
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The patent changes the winding parameter from litz wire to round wire with optimized winding configuration, enabling high current handling capability while minimizing fringing field effects. This parameter change allows the transformer to achieve high-power applications with reduced winding losses compared to conventional integrated transformers.

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

The solution enables efficient operation in high-current, low-voltage applications with reduced winding losses and increased flexibility, as the integrated inductances and stray inductance management minimize fringing fields and optimize transformer performance.

Implementation Method 1

The second electrical winding (7) is wound around the first leg (3) and the second leg (4) so as to form, together with the magnetic core (2), an integrated resonant inductance and an integrated magnetizing inductance

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4273894A1Converter component and converter
Publication Date: 2023.11.08 DELTA ELECTRONICS (THAILAND) PUBLIC CO LTD
  • EP4273894A1 patent drawingFigure 1
  • EP4273894A1 patent drawingFigure 2
  • EP4273894A1 patent drawingFigure 3

AI summary

The invention concerns a converter component (1), especially for LLC resonant converters, comprising a magnetic core (2) with at least three legs (3, 4, 5), at least one first electrical winding (6), and at least one second electrical winding (7). Therein, the second electrical winding (7) is wound so as to at least once and at least partially surround at least a first leg (3) and a second leg (4) of the at least three legs (3, 4, 5) of the magnetic core (2). The invention also concerns a converter (100) comprising the converter component (1).