Capacitor-Free Harmonic Filter Using Opposed Coil Windings

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Solution Overview

Problem

Existing harmonic filters for single-phase and three-phase alternating current installations rely heavily on capacitors, which are bulky and prone to deterioration, necessitating a more durable and efficient alternative.

Innovation Solution

A harmonic filter design utilizing helical coils wound in opposite directions around a ferromagnetic core to cancel out odd harmonics, eliminating the need for capacitors and enhancing energy efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If capacitors are used in harmonic filters, then filtering performance is achieved, but weight and size increase significantly

Engineering Contradiction:
Improvefiltering performanceVSAvoidfilter weight
Core Design Contradiction:
ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent extracts and removes the capacitor component from the traditional harmonic filter circuit, replacing it with an inductor-based solution. This eliminates the heavy and bulky capacitor while maintaining the filtering function through alternative electromagnetic principles.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes the electrical field-based capacitor with a magnetic field-based inductor system. By using electromagnetic induction and magnetic coupling between inductors, the solution replaces the electrostatic mechanism with an electromagnetic one, achieving filtering without capacitors.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If capacitors are used in harmonic filters, then filtering performance is achieved, but device size increases

Engineering Contradiction:
Improvefiltering performanceVSAvoidfilter size
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The capacitor is extracted from the circuit topology, removing the need for large physical capacitor components. The inductor-based design occupies less space while achieving the same harmonic filtering objective.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The inductors in the patent serve multiple functions: they provide filtering action, enable voltage boosting, and facilitate power transfer. This multi-functionality reduces the need for separate components, thereby reducing overall device size.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If capacitors are used in harmonic filters, then filtering capability is provided, but reliability decreases due to deterioration

Engineering Contradiction:
Improvefiltering capabilityVSAvoidcomponent lifespan
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

By removing the capacitor from the circuit, the patent eliminates the component subject to deterioration. Inductors are inherently more durable and have longer operational lifespans, thereby improving the overall reliability and service life of the harmonic filter.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses inductors which are more robust and longer-lasting compared to capacitors. This substitution with more durable components ensures extended operational duration and reduced maintenance requirements.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Reliability

If traditional harmonic filter configuration is used, then filtering is achieved, but energy consumption increases

Engineering Contradiction:
Improvefiltering functionVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces the passive capacitor-based filtering mechanism with an active inductor-based electromagnetic system that can operate more efficiently. The inductors enable energy recovery and reduce losses through magnetic coupling, thereby lowering overall energy consumption.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent modifies the circuit parameters by using specific inductor configurations and winding arrangements that optimize magnetic coupling and reduce resistive losses. This parameter optimization leads to improved energy efficiency while maintaining filtering performance.

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 design effectively attenuates odd harmonics and reduces energy consumption by canceling out current directions, offering a compact and durable solution without capacitors.

Implementation Method 1

a first helical coil, arranged in series between the phase input and the phase output of the filter; a second helical coil, arranged in series between the phase input of the filter and the neutral input of the filter; a ferromagnetic core around which the first helical coil and the second helical coil are wound; where the first helical coil has a winding direction opposite to the winding direction of the second helical coil

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The design effectively attenuates odd harmonics and reduces energy consumption by canceling out current directions

Methodology Applied
Scientific EffectMagnetic field cancellation: Magnetic Field

Data Source

PatentEP4607733B1Harmonic filter for alternating current installations
Publication Date: 2026.02.11 ISTA SE
  • EP4607733B1 patent drawingFigure 1
  • EP4607733B1 patent drawingFigure 2

AI summary

The present invention discloses a harmonic filter (1,2) for single-phase and three-phase alternating current installations using two coils (10, 11) arranged in series, each of which is helically wound around the same ferromagnetic core (9,9'), but in opposite winding directions, to filter the harmonics generated in current. Advantageously, unlike filters of the state of the art, the disclosed harmonic filter lacks capacitors.