Filter Module Layout for Differential and Common Mode Noise

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Solution Overview

Problem

Existing filter modules for reducing differential and common mode electrical noise are often costly, require additional material and space, and have complex manufacturing processes due to the use of multiple components and precise positioning requirements.

Innovation Solution

A filter module design featuring preassembled circuit boards with bypass capacitors between common mode chokes, using ferrite cores with a single turn inductor configuration and insulating sheaths to minimize contact and reduce material usage, along with spring contacts for electrical connections, which simplifies assembly and reduces costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dual mode choke with ferrite cores is used to suppress both differential and common mode noise, then noise suppression effectiveness is improved, but weight and material costs are increased

Engineering Contradiction:
Improvenoise suppression effectivenessVSAvoidfilter module weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The filter module is segmented into separate functional sections: common mode chokes for common mode noise suppression, differential mode filters for differential noise suppression, and bypass capacitors. This segmentation allows each component to be optimized independently, reducing the need for heavy dual-mode ferrite cores while maintaining overall noise suppression effectiveness.

Inventive Principle:
Principle #1Segmentation

2Reliability

If dual mode choke with ferrite cores is used to suppress both differential and common mode noise, then noise suppression effectiveness is improved, but material costs are increased

Engineering Contradiction:
Improvenoise suppression effectivenessVSAvoidferrite core material quantity
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The filter module is segmented into separate functional sections: common mode chokes for common mode noise suppression, differential mode filters for differential noise suppression, and bypass capacitors. This segmentation allows each component to be optimized independently, reducing the need for heavy dual-mode ferrite cores while maintaining overall noise suppression effectiveness.

Inventive Principle:
Principle #1Segmentation

3Reliability

If busbars are embedded in common mode choke for manufacturing, then electrical connection is improved, but manufacturing complexity and costs are increased

Engineering Contradiction:
Improveelectrical connection qualityVSAvoidmanufacturing simplicity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The busbars are pre-assembled with insulating sheaths before being installed in the housing. The insulating sheaths are pre-applied to the busbars, which simplifies the final assembly process and eliminates the need for complex embedding operations during manufacturing, while still ensuring good electrical connections.

Inventive Principle:
Principle #10Preliminary action

4Reliability

If circuit board is surrounded by common mode choke, then common mode noise suppression is improved, but weight and material costs are increased

Engineering Contradiction:
Improvecommon mode noise suppressionVSAvoidfilter module weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The common mode suppression function is extracted from a large surrounding choke structure and implemented using discrete common mode choke components positioned near the busbars. This extraction reduces the overall material quantity and weight while maintaining effective common mode noise suppression through targeted placement.

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 achieves effective noise reduction with reduced material and space requirements, simpler manufacturing, and improved thermal insulation, while maintaining low impedance for high-frequency responses.

Implementation Method 1

The ferrite cores are designed in such that they create a single turn inductor with respect to each bus bar in order to suppress differential noise

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the ferrite cores provide a single turn inductor with respect to both bus bars in order to suppress common mode noise

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

The filter module comprises at least a first bypass capacitor which is electrically connected to the first busbar and the second busbar

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 4

a first common mode choke and a second common mode choke are arranged in the housing and being spaced apart each other

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3925071B1Filter module for reducing differential and common mode noise and method to manufacture such a filter module
Publication Date: 2022.11.30 MAHLE INT GMBH
  • EP3925071B1 patent drawingFigure 1~2
  • EP3925071B1 patent drawingFigure 3~4
  • EP3925071B1 patent drawingFigure 5~6

AI summary

A filter module (1) for reducing differential and common mode electrical noise comprising: two busbars (2,3), an at least partially electrically conductive housing (4),a two common mode choke (5,6) arranged in the housing (4), the common mode chokes (5,6) being formed by ferrite cores (7,8), at least a first bypass capacitor (9) connected to the busbars (2,3), at least a second bypass capacitor (10) connected to the first busbar (2) and a midpoint (11), at least a third bypass capacitor (12) connected to the second busbar (3) and the midpoint (11), the first bypass capacitor (9), the second bypass capacitor (10) and the third bypass capacitor (12) being arranged on a circuit board (13), the circuit board (13) being arranged in the housing (4) between the ferrite cores (7,8) and having first spring contacts (14,15) providing an electrical connection between the circuit board (13) and the busbar (2, 3).