Notch Filter Attenuation Control via Frequency-Dependent Resistance

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Solution Overview

Problem

Existing notch filters lack control over attenuation levels above the notch resonance frequency, leading to inefficiencies in noise filtering in electrical systems.

Innovation Solution

Incorporating an attenuation control resistance in parallel or series with the notch inductance and capacitance allows for adjustable attenuation control above the notch resonance frequency, enabling improved noise filtering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a prior art notch filter is used, then the notch resonance frequency is defined, but the attenuation above the notch resonance frequency cannot be controlled

Engineering Contradiction:

Improveattenuation controlVSAvoidfilter structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent introduces an attenuation control resistance connected in parallel with the notch inductance, allowing the attenuation above the notch resonance frequency to be controlled by adjusting the resistance value. This parameter change enables versatile attenuation control without fundamentally altering the filter structure

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The attenuation control resistance acts as an intermediary element that mediates between the notch inductance and the output, providing controlled attenuation above the notch resonance frequency while maintaining the original notch filtering functionality

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If a fixed resistance value is used, then the circuit is simple, but the attenuation cannot be adjusted with frequency

Engineering Contradiction:

Improvefrequency-dependent attenuationVSAvoidresistance configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent employs a frequency-dependent resistance (such as an inductor with complex permeability or a capacitor in ESR mode) that dynamically changes its resistance value with frequency. This allows the attenuation to be automatically adjusted according to the frequency, providing adaptability without complex control circuits

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The frequency-dependent resistance automatically adjusts its own value based on the operating frequency, enabling the filter to self-regulate its attenuation characteristics without external control mechanisms

Inventive Principle:

Principle #25Self-service

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 effectively manages attenuation levels, enhancing the performance of notch filters by allowing for customizable resistance values that adjust with frequency, thereby improving noise filtering efficiency.

Implementation Method 1

a notch inductance L N and a notch capacitance C N in series defining a notch resonance frequency

Methodology Applied

Scientific EffectResonance: Resonance

Implementation Method 2

the notch resistance is a frequency dependent resistance

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Data Source

PatentEP3955461A1Notch filter with frequnecy dependent resistance and electrical system comprising such notch filter

Publication Date: 2022.02.16 VALEO ELECTRIFICATION

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AI summary

The EMC notch filter (404,1304) comprises a notch inductance (LN,LLC ) and a notch capacitance (C2 π ,CN) defining a notch resonance frequency. The notch filter (404,1304) further comprises an attenuation control resistance (R N ) in parallel with the notch inductance if the notch inductance and the notch capacitance are in series or in series with the notch capacitance if the notch inductance and the notch capacitance are in parallel. The attenuation control resistance is intended to be frequency dependent in a manner to allow suppression of power line harmonics with decreasing amplitude.