Segmented E-I Magnetic Core for Resonant Circuit Inductance Control

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Solution Overview

Problem

Existing resonant electrical circuits face challenges in precisely and reliably fixing the value of series inductance Lr without increasing the size of the magnetic core, while minimizing eddy current losses.

Innovation Solution

A magnetic component with an 'E'-shaped lower part, an 'E'-shaped upper part, and an 'I'-shaped central part, featuring coils wound around the central branches, where the central part has lower reluctance than the lower and upper parts, and optionally includes air gaps to control inductance, with strong coupling between coils to achieve high mutual inductance and series inductance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the coupling between coils is reduced to create series inductance Lr, then the size of the resonant electrical circuit can be reduced, but it is difficult to reach large values of series inductance Lr without increasing the size of the magnetic core and causing eddy current losses

Engineering Contradiction:
Improvesize of resonant electrical circuitVSAvoideddy current losses
Core Design Contradiction:
Volume of moving objectVSLoss of energy

Solution Approach 1:

The magnetic core is segmented into three distinct parts: a lower E-shaped part, an upper E-shaped part, and a central I-shaped part. This segmentation allows independent optimization of each part's properties. The lower and upper parts can be designed with higher reluctance materials, while the central part uses low reluctance material to minimize eddy current losses and achieve the desired series inductance Lr without increasing overall size.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different parts of the magnetic core have different reluctance characteristics tailored to their specific functions. The central part has low reluctance to minimize losses, while the lower and upper parts have higher reluctance. This local differentiation of magnetic properties allows the system to achieve large series inductance values without the drawbacks of uniformly increasing core size or using high-loss materials throughout.

Inventive Principle:
Principle #3Local quality

2Volume of moving object

If the coupling between coils is reduced to create series inductance Lr, then the size of the resonant electrical circuit can be reduced, but it is difficult to fix the value of series inductance Lr precisely and reliably

Engineering Contradiction:
Improvesize of resonant electrical circuitVSAvoidprecision and reliability of series inductance Lr value
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

By segmenting the magnetic core into separate lower, central, and upper parts with controlled magnetic coupling, the series inductance Lr can be precisely determined by the physical dimensions and material properties of each segment. This structured segmentation provides reliable and reproducible inductance values that are less sensitive to manufacturing tolerances compared to relying solely on coil positioning.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The central I-shaped magnetic part acts as an intermediary element that mediates the magnetic coupling between the lower and upper E-shaped parts. By controlling the properties of this intermediate component, the series inductance Lr can be precisely and reliably fixed, as the central part's low reluctance and defined geometry provide a stable reference for inductance calculation and manufacturing.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Loss of energy

If the magnetic core size is increased to reach large values of series inductance Lr, then the series inductance can be increased, but the bulk of the magnetic core increases

Engineering Contradiction:
Improveseries inductance Lr valueVSAvoidbulk of the magnetic core
Core Design Contradiction:
Loss of energyVSVolume of moving object

Solution Approach 1:

Instead of uniformly increasing the entire magnetic core size, the invention applies local quality optimization by using low reluctance material specifically in the central I-shaped part where it is most effective for minimizing losses and achieving the desired inductance. The lower and upper E-shaped parts maintain higher reluctance, allowing the system to achieve large series inductance Lr values without proportionally increasing the overall core bulk.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The magnetic core employs a composite structure combining different magnetic materials with different reluctance properties in specific locations. The central part uses low reluctance material while the outer parts use higher reluctance materials, creating a composite magnetic circuit that achieves high series inductance Lr values with minimized overall volume and reduced eddy current losses.

Inventive Principle:
Principle #40Composite materials

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 allows for precise and reliable control of series inductance Lr, reduces the bulk size of the magnetic core, and minimizes eddy current losses, enhancing the compactness and efficiency of the resonant electrical circuit.

Implementation Method 1

the central part having a lower reluctance both than that of the lower part along each lower magnetic circuit and than that of the upper part along each upper magnetic circuit

Methodology Applied
Scientific EffectMagnetic flux: Magnetic Field

Implementation Method 2

a first coil and a second coil wound around a central branch of the lower part to be coupled together another, a third coil wound around a central branch of the upper part

Methodology Applied
Scientific EffectMagnetic coupling: Electromagnetic Induction

Implementation Method 3

the central part having a lower reluctance both than that of the lower part along each lower magnetic circuit and than that of the upper part along each upper magnetic circuit

Methodology Applied
Scientific EffectMagnetic reluctance: Magnetic Reluctance

Data Source

PatentEP3229247B1Magnetic component, resonant electric circuit, electric converter and electrical system
Publication Date: 2019.01.02 VALEO SIEMENS EAUTOMOTIVE FRANCE SAS
  • EP3229247B1 patent drawingFigure 1~2
  • EP3229247B1 patent drawingFigure 3~4
  • EP3229247B1 patent drawingFigure 5~6

AI summary

The magnetic component comprises: a magnetic core (118) having a lower part (120) in the shape of an "E", an upper part (122) in the shape of an "E" and a central part (124) in the shape of an "I" closing both the lower part (120) and the upper part (124) such that the lower part (120) and the central part (124) define two lower magnetic circuits and the upper part (122) and the central part (124) define two upper magnetic circuits; a first coil (130) and a second coil (132) wound around a central branch of the lower part (120) to be coupled to each other; a third coil (134) wound around a central branch of the upper part (122), the third coil (134) being connected in series with the second coil (132).The central part (124) has a lower reluctance than both that of the lower part (120) along each lower magnetic circuit and that of the upper part (122) along each upper magnetic circuit.