Flexible PCB Rogowski Coil for Uniform Turn Manufacturing

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Solution Overview

Problem

Existing Rogowski coils are impractical for mass production due to mechanical complexity, high costs, and difficulty in achieving evenly spaced and identical turns, which reduces flexibility and increases expenses.

Innovation Solution

A flexible printed circuit Rogowski coil design featuring a first and second portion of an air coil printed as patterns on opposite sides of a flexible printed circuit board, connected through via centers, allowing for scalable and cost-effective production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a traditional air coil with evenly spaced turns is constructed using wire and supporting core, then measurement precision is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvemeasurement precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the traditional mechanical wire-winding system with a printed circuit board (PCB)-based coil structure. The coil turns are formed by conductive traces printed on the PCB surface, eliminating the need for manual wire winding, supports, and mechanical fastening systems. This substitution maintains measurement precision while dramatically reducing device complexity and enabling automated manufacturing.

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

Solution Approach 2:

The patent changes the physical state and form of the coil from a three-dimensional wire structure to a two-dimensional planar pattern on a flexible substrate. This parameter change allows the coil to be manufactured using standard PCB printing processes, achieving uniform turn spacing and identical geometry through controlled printing parameters rather than mechanical assembly.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If a supporting core is used to achieve evenly spaced turns, then manufacturing precision is improved, but flexibility and cost worsen

Engineering Contradiction:
Improvemanufacturing precisionVSAvoidease of manufacture
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent eliminates the mechanical supporting core by using a flexible printed circuit board as the structural base. The coil traces are directly printed on the flexible PCB, which provides both structural support and electrical connection pathways. This integration removes the need for separate supporting cores and simplifies the manufacturing process to standard PCB fabrication steps.

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

3Stability of the object's composition

If wire with large cross-sectional area is used for self-supporting configuration, then structural stability is improved, but flexibility and cost worsen

Engineering Contradiction:
Improvestructural stabilityVSAvoidease of manufacture
Core Design Contradiction:
Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent uses a flexible printed circuit board as the structural foundation, which is a thin film that provides both mechanical support and electrical conductivity. The coil traces are printed on this flexible substrate, eliminating the need for thick, rigid wires. The flexible PCB maintains structural stability through its layered construction while preserving flexibility for wrapping around conductors of various sizes.

Inventive Principle:
Principle #30Flexible shells and thin films

4Ease of operation

If traditional wire winding method is used, then ease of operation is maintained, but productivity and manufacturing cost worsen

Engineering Contradiction:
Improveease of operationVSAvoidproductivity
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The patent replaces manual wire winding operations with automated PCB printing processes. The coil patterns are created using standard PCB fabrication techniques such as screen printing or photolithography, which can be fully automated. This substitution maintains the ease of operation for installation while dramatically increasing manufacturing productivity and reducing labor costs.

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

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 flexible printed circuit Rogowski coil enables cost-effective mass production while maintaining the advantages of traditional Rogowski coils, such as non-intrusive installation and high signal-to-noise ratio immunity.

Implementation Method 1

A Rogowski coil is an electrical apparatus that can be used for quantitatively and qualitatively measuring alternating current (AC) or high-speed transient or pulsing current by using both Ampere's law and Faraday's law

Methodology Applied
Scientific EffectFaraday's law of induction: Electromagnetic Induction

Implementation Method 2

Voltage generated at the terminals 106 is governed by Faraday's law of induction as follows: where k is a proportionality constant reflecting a configuration of the air coil 102

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4502625A1Flexible printed circuit rogowski coil
Publication Date: 2025.02.05 LITTELFUSE EUROPE GMBH
  • EP4502625A1 patent drawingFigure 1
  • EP4502625A1 patent drawingFigure 2A~2B
  • EP4502625A1 patent drawingFigure 3A~3B

AI summary

A flexible printed circuit Rogowski coil is provided and can include a flexible printed circuit board, a first connector disposed proximate a first end of the flexible printed circuit board, a second connector disposed proximate the first end of the flexible printed circuit board, a first portion of an air coil printed as a first pattern a top side of the flexible printed circuit board and connected to the first connector, and a second portion of the air coil printed as a second pattern on a bottom side of the flexible printed circuit board and connected to the second connector, the second pattern corresponding to the first pattern.