Coil Component Inductance Balance via Variable Core Diameter

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing coil components with stacked lower and upper coils on a core suffer from a difference in inductance due to a discrepancy in the number of turns, leading to imbalance in characteristic performance.

Innovation Solution

The coil component design includes a first core with a mounting surface and a coil placing surface, where the lower coil has one end drawn to a first area and the other end to a second area, and the upper coil is coaxially stacked with one end drawn to a third area and the other to a fourth area, with a second core of varying diameter through the inner diameter areas of both coils to adjust inductance, ensuring the number of turns differs by less than one turn.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the lower and upper coils are stacked one on the other with winding start and end positions arranged to fit the core mounting surface, then the device complexity is reduced and manufacturing is simplified, but the inductance balance between the two coils deteriorates due to less than one turn difference

Engineering Contradiction:

Improvecoil stacking structureVSAvoidinductance balance

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by making the second core have different diameters at different sections. Specifically, the second core has a first diameter at the section surrounded by the lower coil and a second diameter at the section surrounded by the upper coil, where the diameters differ by 0.5mm to 1.5mm. This local variation in core diameter compensates for the inductance difference caused by the less than one turn difference between coils, thereby achieving inductance balance while maintaining the simplified stacked structure

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the physical parameter of the second core diameter to adjust inductance. By varying the core diameter (first diameter vs. second diameter differing by 0.5mm to 1.5mm) at different sections corresponding to different coils, the magnetic path length and thus the inductance are adjusted to compensate for the turn number difference, achieving balanced inductance values between the lower and upper coils

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the number of turns of the lower and upper coils are made equal, then the inductance balance is improved, but the winding layout complexity increases and manufacturing becomes more difficult

Engineering Contradiction:

Improveinductance balanceVSAvoidwinding layout

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Instead of making the winding layouts complex to achieve equal turns, the patent applies local quality by varying the second core diameter at different sections. This allows the use of simpler winding layouts where the lower and upper coils can have less than one turn difference, while the local diameter variation of the second core compensates for this difference to achieve balanced inductance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent inverts the conventional approach by not trying to make the number of turns equal, but rather accepting a less than one turn difference and compensating through the opposite method - varying the core diameter instead of varying the turn count. This simplifies the winding layout while achieving the same inductance balance goal

Inventive Principle:

Principle #13The other way round (Inversion)

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 the inductance difference between the lower and upper coils by adjusting the core diameter corresponding to the coil with fewer turns, enhancing inductance balance and reducing DC resistance differences.

Implementation Method 1

a coil component having a structure in which a lower coil and an upper coil are stacked one on the other and disposed on a core having a mounting surface

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The number of turns of one of the lower and upper coils is larger by less than one turn than other one of the lower and upper coils. The diameter of the second core is larger at a first section surrounded by the other one of the lower and upper coils than at a second section surrounded by the one of the lower and upper coils.

Methodology Applied

Scientific EffectMagnetic circuit: Magnetic Field

Data Source

PatentUS11328860B2Coil component

Publication Date: 2022.05.10 TDK CORP

AI summary

Disclosed herein is a coil component that includes: a first core having a mounting surface and a coil placing surface positioned opposite to the mounting surface; a lower coil placed on the coil placing surface such that a coil axis of the lower coil extends substantially perpendicular to the coil placing surface; an upper coil substantially coaxially stacked on the lower coil; and a second core disposed through inner diameter areas of the lower and upper coils. The number of turns of one of the lower and upper coils is larger by less than one turn than other one of the lower and upper coils. The diameter of the second core is larger at a first section surrounded by the other one of the lower and upper coils than at a second section surrounded by the one of the lower and upper coils.