EMC Filter Core Layout for Vibration-Stable Gap and Lower Bus Bar Heat

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Solution Overview

Problem

Existing EMC filters are vulnerable to external vibrations and shocks, leading to gap disruption in the core, which causes saturation of large currents and generates heat due to fringing fields, compromising the effectiveness of electromagnetic noise reduction.

Innovation Solution

The EMC filter design includes a U-shaped lower bobbin and core with a bus bar extending below the gap, maintained by a hard metal bus bar, and a plate-like upper core, minimizing gap overlap and using a heat dissipation material to reduce temperature rise and maintain the gap under external stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a plastic bobbin is used to maintain the gap inside the core, then the gap can be maintained during normal operation, but the bobbin becomes vulnerable to external vibration and shock, causing gap disruption

Engineering Contradiction:

Improvegap maintenanceVSAvoidrobustness to external stress

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent replaces the plastic bobbin's mechanical gap-maintaining function with a magnetic field-based solution. The bus bar is positioned to bypass the gap, and the magnetic field generated by the bus bar maintains the gap structure through magnetic forces rather than relying on the mechanical integrity of a plastic component. This substitution eliminates the vulnerability to vibration and shock while maintaining gap stability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces the bus bar as an intermediary element that serves dual functions: carrying the large current and maintaining the gap structure. The bus bar acts as a mediator between the electrical function (current conduction) and the structural function (gap maintenance), eliminating the need for a separate plastic bobbin component that is vulnerable to mechanical stress.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If the bus bar overlaps the gap, then the magnetic field can be contained, but heat is generated in the bus bar by the fringing field, increasing the temperature of the bus bar

Engineering Contradiction:

Improvemagnetic field containmentVSAvoidbus bar temperature

Core Design Contradiction:

Loss of energyVSTemperature

Solution Approach 1:

The patent resolves the contradiction by changing the spatial arrangement from a two-dimensional overlap configuration to a three-dimensional bypass configuration. The bus bar is positioned to extend below the gap height level, moving it out of the gap plane entirely. This dimensional change allows the magnetic field to be contained within the core structure while the bus bar operates in a separate spatial zone, avoiding exposure to the fringing field and reducing heat generation.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If the bobbin is damaged by external vibration and impact, then the gap inside the core cannot be maintained, but redesigning the bobbin to be more robust increases device complexity

Engineering Contradiction:

Improvegap maintenance under stressVSAvoidbobbin structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the gap-maintaining function from the bobbin structure entirely. Instead of designing a more robust bobbin, the solution removes the bobbin's structural role in gap maintenance and assigns this function to the magnetic field and bus bar arrangement. This extraction simplifies the bobbin design while improving reliability, as the gap maintenance becomes independent of the bobbin's mechanical integrity.

Inventive Principle:

Principle #2Taking out (Extraction)

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 design effectively maintains the gap under external vibrations, reduces temperature increase due to fringing fields, and enhances cooling efficiency while ensuring robustness against mechanical stress.

Implementation Method 1

According to a fringing effect, heat is generated in the bus bar by a magnetic field (fringing field) generated in the gap inside the core, thereby increasing a temperature of the bus bar

Methodology Applied

Scientific EffectFringing effect: Electromagnetic Induction

Implementation Method 2

a heat dissipation material applied to a portion of the bus bar and a portion of the lower core not covered by the bus bar and exposed upwardly

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS12445049B2EMC filter for electromagnetic regulation of converter and manufacturing method thereof

Publication Date: 2025.10.14 HYUNDAI MOBIS CO LTD

AI summary

Provided is an electro-magnetic compatibility (EMC) filter including a lower bobbin having a U-shaped cross-sectional shape, a lower core including a magnetic material having a U-shaped cross-sectional shape and disposed on the lower bobbin, a bus bar disposed on the lower core, an upper bobbin having a hollow inside, having a hexahedral shape with one side open, and configured to cover an upper portion of the lower bobbin, and an upper core including a magnetic material having a plate-like shape, disposed in an internal space of the upper bobbin, and disposed on the lower core (U core) to cover the bus bar with a gap maintained by the bus bar between the upper and lower cores when the lower bobbin and the upper bobbin are coupled to each other.