Rogowski Coil Sensory Circuit for Fastener Current Measurement
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Solution Overview
Problem
Measuring current flows through individual components in a multi-component structural composite joint is challenging due to space limitations and high electromagnetic interference, particularly in mechanically fastened skin-substructure joints, which are prone to sparking during lightning strikes, posing a risk to aircraft safety.
Innovation Solution
A system and method using a printed circuit board etched with Rogowski coil sensory circuits, inserted between structures with fasteners, to detect and integrate current flows, featuring passive integrator circuits and a processing unit for accurate measurement and analysis of current profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional Rogowski coils are used for current measurement, then measurement precision is improved, but device complexity and space requirements increase making them impracticable
Solution Approach 1:
The patent replaces the conventional mechanical Rogowski coil with an integrated circuit implementation. The Rogowski coil function is substituted by etching conductive traces directly onto a printed circuit board, creating a planar current sensor that maintains measurement precision while dramatically reducing device complexity and space requirements.
Solution Approach 2:
The patent transitions from a three-dimensional volumetric Rogowski coil to a two-dimensional planar trace pattern on a PCB. This dimensional reduction allows the measurement function to be integrated into the existing joint structure without adding significant volume or complexity.
2Measurement precision
If measurement devices are inserted into densely fastened joints, then current measurement capability is improved, but space limitations prevent device installation
Solution Approach 1:
The patent merges the measurement function with the existing structural components by integrating Rogowski coil traces directly into the PCB that forms part of the joint assembly. This eliminates the need for separate measurement devices and allows current measurement without occupying additional space in the densely fastened joint.
Solution Approach 2:
The patent segments the measurement function into individual trace patterns for each fastener, allowing independent measurement of current through each fastener. This segmentation enables the measurement system to be distributed across multiple locations without requiring a single large measurement device.
3Measurement precision
If passive integrator circuits are used to capture transient pulses, then measurement accuracy for lightning strikes is improved, but device complexity increases
Solution Approach 1:
The patent employs passive integrator circuits that automatically capture and integrate transient current pulses without requiring active control or complex processing. The passive nature of these circuits allows them to self-serve the measurement function during lightning strikes, maintaining measurement accuracy while minimizing added complexity.
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
Enables precise measurement of current flows through fasteners in composite joints, helping to determine the effectiveness of design modifications in preventing damage from lightning strikes and ensuring aircraft safety by accurately capturing transient pulses and integrating them into usable output for certification and design improvements.
Implementation Method 1
Rogowski coils are used for current measurement because of the large amount of electromagnetic interference (EMI) noise that it commensurate with extreme changes in current flow
Implementation Method 2
transmitting the detected current from each fastener to a corresponding passive integrator circuit for capturing transient pulses and integrating the pulses into an output
Data Source
Figure 1a~1b
Figure 2~6
Figure 3
AI summary
A method and apparatus for simultaneously measuring current flows through fasteners in a multi-structure composite joint is provided. The method comprising inserting a printed circuit board between at least two structures, the printed circuit board being etched with at least one Rogowski coil sensory circuit, the at least two structures being joined with at least one fastener extending through the at least one Rogowski coil sensory circuit in the printed circuit board; detecting current in the at least one fastener; transmitting the detected current from each fastener to a corresponding passive integrator circuit for capturing transient pulses and integrating the pulses into an output; and transmitting the output to a processing unit.