Multi-Carrier Reflectometry Arc Detection in Avionics Circuits
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Solution Overview
Problem
Conventional electric arc detection systems in avionics systems face challenges in reliably detecting series and parallel arcs, especially due to noise saturation and low impedance variations, which affect detection thresholds and accuracy in constrained environments.
Innovation Solution
A method using Multi Carrier Time Domain Reflectometry (MCTDR) that transmits a high-frequency signal, filters out frequencies below a cut-off frequency, and employs two thresholds of different signs to detect and locate series and parallel arcs, reducing noise impact and unnecessary signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the detection threshold is lowered to detect series arcs with low impedance variation, then the detection sensitivity for series arcs is improved, but the system becomes saturated by broadband impulse noise from the electric arc phenomenon
Solution Approach 1:
The frequency spectrum is segmented into multiple bands using multiple carryors at different frequencies. The signal is divided into discrete frequency components that can be processed independently, allowing the system to distinguish between noise and actual arc signals across different frequency ranges.
Solution Approach 2:
The system changes the frequency parameter by using multiple carryors at different frequencies rather than a single fixed frequency. This allows the detection threshold to be adjusted relative to the noise floor at each frequency, improving sensitivity while avoiding noise saturation.
2Device complexity
If a single threshold is used for arc detection, then the system complexity is reduced, but the ability to detect both series and parallel arcs is compromised
Solution Approach 1:
The threshold is made dynamic rather than static. The system automatically adjusts the threshold based on the detected signal characteristics and the specific type of arc (series or parallel), allowing optimal detection for both arc types without requiring multiple fixed thresholds.
Solution Approach 2:
The threshold parameter is changed dynamically based on the operating conditions and arc type. The system modifies the threshold value in response to the detected signal patterns, enabling reliable detection of both series and parallel arcs with a single adaptive threshold mechanism.
3Reliability
If the reflectometry signal is transmitted continuously across all frequencies, then the detection coverage is maximized, but the energy consumption and unnecessary transmission increase
Solution Approach 1:
The frequency spectrum is segmented into discrete carryor frequencies. Instead of transmitting continuously across all frequencies, the system transmits only at specific segmented frequency points, reducing unnecessary transmission while maintaining detection coverage through the multi-carrier approach.
Solution Approach 2:
The signal transmission is performed periodically at discrete frequency intervals rather than continuously. The multi-carrier signal is transmitted in periodic bursts at optimized frequency points, reducing energy consumption while maintaining effective detection through the cumulative effect of multiple periodic transmissions.
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 enhances the reliability and accuracy of arc detection and location by optimizing frequency band usage, reducing noise interference, and improving detection performance in aeronautical environments.
Implementation Method 1
One such method consists of injecting a signal into a cable and then of detecting the waves reflected on the different characteristic impedance discontinuities
Implementation Method 2
This technology is for example described in detail in the application WO2016192980. The transmitted signal is a Multi Carrier Time Domain Reflectometry MCTDR signal
Implementation Method 3
filtering the acquired signal so as to eliminate signals having a frequency lower than a cut-off frequency, the cut-off frequency having for example a value between a few tens of kHz and a few hundred MHz
Data Source
AI summary
The invention relates to a method for detecting and locating a fault by reflectometry in an electrical circuit, such a method comprising the steps of: —emitting a reflectometry signal in a line of the circuit to be studied; —acquiring an electrical variable of the reflected signal passing through the network; —filtering the acquired signal so as to eliminate signals having a frequency lower than a cutoff frequency, the cutoff frequency having a value between 100 kHz and 1 GHz; —analysing an acquired signal so as to detect a fault.