Power Line EMI Filter Integration Without Capacitors

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Solution Overview

Problem

Existing EMI filters require additional power cords and capacitors for connection, which can be cumbersome and pose safety risks, especially for human contact.

Innovation Solution

Integrating EMI filters with power lines using high impedance inductors along the ground wire, eliminating the need for capacitors and enabling a safer, more convenient connection method.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional EMI filters use capacitors for connection, then EMI filtering performance is improved, but device complexity and safety risks increase

Engineering Contradiction:
ImproveEMI filtering performanceVSAvoidconnection structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the EMI filter with the power line structure by integrating the filter components directly into the power cord assembly. The filter housing is combined with the power cord connector, eliminating the need for separate capacitor-based filtering components and simplifying the overall connection structure while maintaining EMI filtering effectiveness.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts and eliminates the capacitor components from the EMI filter design, replacing them with an inductor-based filtering mechanism integrated into the power line. This removal of capacitors reduces device complexity and safety risks while the inductor-based approach maintains the essential EMI filtering function.

Inventive Principle:
Principle #2Taking out (Extraction)

2Object-affected harmful factors

If additional power cords and capacitors are used for EMI filtering, then EMI suppression is improved, but ease of operation deteriorates

Engineering Contradiction:
Improvecommon mode interferenceVSAvoidconnection convenience
Core Design Contradiction:
Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The EMI filter is merged with the power cord assembly into a single integrated unit. The filter housing incorporates the power cord connector and inductor components, allowing users to connect the device to power while automatically receiving EMI filtering protection without requiring separate filtering components or complex wiring.

Inventive Principle:
Principle #5Merging (Combining)

3Object-affected harmful factors

If capacitors are used in EMI filter connection, then differential mode noise filtering is improved, but safety risks increase

Engineering Contradiction:
Improvedifferential mode noiseVSAvoidsafety for human contact
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent removes capacitors from the EMI filter design and replaces them with an inductor-based filtering system. This extraction of capacitor components eliminates the safety risks associated with capacitor leakage and electrical shock hazards while maintaining the ability to filter differential mode noise through the inductor's inherent electrical properties.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the filtering mechanism from capacitor-based to inductor-based, fundamentally altering the electrical parameters of the filter. The inductor provides filtering through its inductive reactance rather than capacitive reactance, achieving noise suppression while improving safety for human contact by eliminating capacitor-related hazards.

Inventive Principle:
Principle #35Parameter changes

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 solution provides a compact, easy-to-use EMI filter structure with low leakage current, ensuring compliance with safety standards and effective suppression of common mode interference signals.

Implementation Method 1

The common mode choke includes a coil or winding with multiple turns of wire around a magnetic core. The magnetic core material and winding configuration are designed to create a high impedance to common mode noise

Methodology Applied
Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Implementation Method 2

The common mode choke of the EMI filter is configured to block, attenuate, or filter out common mode noise using a coil or winding with multiple turns of wire around a magnetic core

Methodology Applied
Scientific EffectMagnetic Field: Magnetic Field

Implementation Method 3

a third or high impedance inductor is added along the ground wire of an EMI filtering circuit

Methodology Applied
Scientific EffectElectrical Impedance: Electrical Resistance

Data Source

PatentEP4701076A1Integrating and/or combining EMI filters with power lines
Publication Date: 2026.02.25 STEWARD FOSHAN MAGNETICS CO LTD
  • EP4701076A1 patent drawingFigure 1
  • EP4701076A1 patent drawingFigure 2
  • EP4701076A1 patent drawingFigure 3

AI summary

Exemplary embodiments are disclosed of circuits for integrating and/or combining electromagnetic interference, EMI, filters with power lines without using capacitors. In exemplary embodiments, a circuit (320) comprises a common mode inductor (324) including first (328) and second inductors (332). The first inductor (328) is configured to be operable for providing a first impedance along a live wire (336) of the circuit (320). The second inductor (332) is configured to be operable for providing a second impedance along a neutral wire (340) of the circuit (320). The circuit (320) further includes a third inductor (344) configured to be operable for providing a third impedance along a ground wire (348) of the circuit (344).