Rogowski Coil Active Capacitance Compensation

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Solution Overview

Problem

Conventional Rogowski-Steinhaus-Chattock coils face measurement accuracy limitations due to electrical capacitances, especially at high frequencies, which affect the accuracy of AC current measurements and reduce bandwidth.

Innovation Solution

The method involves using a Rogowski-Steinhaus-Chattock coil with an active capacitance compensation system, where a partitioning line is interwoven into the coil turns to minimize capacitive coupling by actively feeding the electrical potential of the coil turns into the partitioning line through a feedback loop, reducing the capacitive load and voltage differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the number of turns in the Rogowski-Steinhaus-Chattock coil is increased to improve sensitivity, then measurement sensitivity is improved, but capacitive coupling between turns increases leading to reduced measurement accuracy at high frequencies

Engineering Contradiction:

Improvemeasurement sensitivityVSAvoidcapacitive coupling

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The coil winding is divided into multiple segments with partitioning lines, where each segment is independently capacitance-compensated. This segmentation allows the total number of turns to be increased for sensitivity while limiting capacitive coupling within each segment through active compensation circuits.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Active capacitance compensation circuits are implemented that use feedback mechanisms to detect and counteract capacitive coupling effects in real-time. The compensation circuits generate counter-signals that cancel the harmful capacitive coupling between turns, enabling high-frequency measurements with high turn counts.

Inventive Principle:

Principle #23Feedback

2Measurement precision

If the spatial distance between turns is reduced to increase sensitivity, then measurement sensitivity is improved, but voltage differences between turns increase causing greater capacitive coupling effects

Engineering Contradiction:

Improvemeasurement sensitivityVSAvoidvoltage difference between turns

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

Capacitance compensation circuits are implemented that actively maintain equipotential conditions between adjacent turns by detecting voltage differences and applying compensating signals. This reduces the voltage differences between turns even when spatial distance is minimized, thereby reducing capacitive coupling while maintaining sensitivity.

Inventive Principle:

Principle #12Equipotentiality

3Device complexity

If conventional Rogowski-Steinhaus-Chattock coils are used for high-frequency measurements, then device simplicity is maintained, but measurement accuracy deteriorates due to capacitance effects

Engineering Contradiction:

Improvecoil structure simplicityVSAvoidmeasurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

Capacitance compensation circuits are introduced as intermediary elements between the coil turns and the measurement system. These compensation circuits act as mediators that cancel out the harmful capacitive effects while preserving the simple toroidal coil structure, enabling accurate high-frequency measurements without fundamentally changing the basic coil geometry.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 approach effectively reduces the impact of capacitances, enhancing measurement accuracy and bandwidth by minimizing capacitive coupling and resonance, thereby improving the reliability of high-frequency AC current measurements.

Implementation Method 1

The current flow to be measured causes a magnetic field which surrounds the conductor and which induces a voltage in a Rogowski-Steinhaus-Chattock coil situated around the conductor.

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

at least one partitioning line is drawn into coil turns of the Rogowski-Steinhaus-Chattock coil and minimizes a capacitive coupling of the coil turns of the Rogowski-Steinhaus-Chattock coil among one another and/or to at least one further electrical line by virtue of the fact that an electrical potential corresponding to the electrical potential of the coil turns of the Rogowski-Steinhaus-Chattock coil is impressed on the at least one partitioning line by means of an active feedback

Methodology Applied

Scientific EffectCapacitance compensation: Capacitance

Data Source

PatentUS10345342B2Rogowski current with active capacitance compensation

Publication Date: 2019.07.09 DR ING H C F PORSCHE AG

AI summary

A method and a sensor for measuring a time derivative of an AC current flowing through a measurement object are presented, wherein a Rogowski-Steinhaus-Chattock coil is aligned with the measurement object and at least one partitioning line is drawn into coil turns of the Rogowski-Steinhaus-Chattock coil and minimizes a capacitive coupling of the coil turns of the Rogowski-Steinhaus-Chattock coil among one another and/or to at least one further electrical line by virtue of the fact that an electrical potential corresponding to the electrical potential of the coil turns of the Rogowski-Steinhaus-Chattock coil is impressed on the at least one partitioning line by means of an active feedback.