Split-Core Current Sensor with Series-Linked Halfring Coils

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Solution Overview

Problem

Current split-core current sensing devices face challenges in achieving high accuracy due to unstable and non-round shapes, while more accurate designs are complex and costly, and there is a risk of interconnecting cable damage.

Innovation Solution

The design features a chain-like arrangement of at least two current sensors connected in series within a ring-shaped support, divided into two halfring-elements mechanically connected by a hinge, with interconnection cables allowing the device to open without disconnecting the circuit, and a conductive housing for shielding, enabling high accuracy and easy assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a flexible coil design with openable locking mechanism is used, then ease of assembly is improved, but measurement precision deteriorates due to unstable and non-round shape

Engineering Contradiction:
Improveease of assemblyVSAvoidmeasurement precision
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The flexible coil is segmented into multiple discrete linear coils connected in series, with each coil housed in its own housing element. This segmentation allows the coil assembly to be divided into two halfring-elements that can be opened using a hinge mechanism, maintaining ease of assembly while improving shape stability for accurate measurement.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If two solid halves with electrical connectors are used, 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 uses flexible housing elements that can be divided into two halfring-elements connected by a hinge, allowing the device to open like a book. This flexible shell approach maintains measurement precision through stable coil positioning while simplifying assembly and reducing complexity compared to rigid connector-based designs.

Inventive Principle:
Principle #30Flexible shells and thin films

3Measurement precision

If two solid halves with external cable interconnection are used, then measurement precision is improved, but reliability deteriorates due to increased risk of cable damage

Engineering Contradiction:
Improvemeasurement precisionVSAvoidreliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The electrical interconnection between the two halfring-elements is merged into the housing structure itself through integral connection points and sealed cable conduits. This eliminates external vulnerable cables while maintaining the precision measurement capability, significantly improving reliability.

Inventive Principle:
Principle #5Merging (Combining)

4Measurement precision

If linear coils are arranged with equal gaps in series, then measurement precision is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvemeasurement precisionVSAvoidease of manufacture
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The linear coils are pre-assembled with equal gaps in a standardized configuration within each housing element before the final assembly into the halfring-elements. This preliminary preparation simplifies the overall manufacturing process while ensuring the precise equal-gap arrangement necessary for accurate measurement.

Inventive Principle:
Principle #10Preliminary action

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 enhances measurement accuracy, simplifies assembly, and reduces the risk of cable damage while maintaining a cost-effective and robust design by allowing direct mounting on measurement sites without disassembling the circuit.

Implementation Method 1

the housing of said linear coils is either made of at least partly conductive material or has at least partly conductive inner or outer surface treatment

Methodology Applied
Scientific EffectElectromagnetic shielding: Faraday Cage

Implementation Method 2

the current sensors are at least partly linear coils

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2821797B1Current sensing device, and method of manufacturing the same
Publication Date: 2020.11.04 ABB (SCHWEIZ) AG
  • EP2821797B1 patent drawingFigure 1
  • EP2821797B1 patent drawingFigure 2
  • EP2821797B1 patent drawingFigure 3

AI summary

The invention relates to a Current sensing device with at least two current sensors, implemented in an openable ringshaped support, and a method of manufacture the same, according to the preamble of the claims 1 and 11. In order to optimize the current sensor device in the structural shape, in order to enhance the manufacturing, by resulting high accuracy. This is realized by the invention in such, that more than two current sensors are arranged in a chain-like arrangement in the ringshaped support, and that the current sensors are electrically connected in series.