Differential Line Fault Detection via Common-Mode Signal Control
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Solution Overview
Problem
Existing differentially operated line networks in safety-relevant systems, such as motor vehicles, face challenges in identifying line short circuits and/or line interruptions, which can lead to corrupted measurement signals and potentially fatal consequences.
Innovation Solution
A circuit and method are proposed to detect line short circuits and/or line interruptions by controlling common-mode signals in a differentially operated line network. The circuit includes a transconductance amplifier with feedback outputs for control currents, a current comparison circuit to compare control currents with threshold values, and a detection circuit to identify saturation regions of transistors, indicating line faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If symmetrical signal transmission is used in differentially operated line networks, then tolerance against interference radiation is improved, but the ability to detect line short circuits and interruptions deteriorates
Solution Approach 1:
The patent applies preliminary action by injecting test currents into the signal cores before normal operation to proactively detect line short circuits and interruptions. The control circuit continuously monitors voltage drops during these test phases, enabling fault detection before corrupted measurement signals can occur during actual operation.
Solution Approach 2:
The patent uses an intermediary approach by introducing a control circuit as a mediator between the symmetrical signal transmission system and fault detection requirements. This control circuit injects test currents and measures voltage drops, serving as an intermediary mechanism that enables fault detection without disrupting the symmetrical signal transmission's interference tolerance.
2Reliability
If control currents are injected into signal cores for fault detection, then line short circuit detection capability is improved, but signal line loading increases
Solution Approach 1:
The patent applies periodic action by injecting control currents only during specific test phases rather than continuously. The control circuit alternates between normal signal transmission and fault detection phases, injecting test currents periodically to detect line short circuits while minimizing overall signal line loading and energy consumption.
Data Source
AI summary
The present disclosure relates to circuits for detecting a line short circuit and/or a line interruption in a differentially operated line network, comprising at least one control circuit configured to control at least one common-mode signal of the differentially operated line network vis-à-vis a predefined common-mode signal variable and to indicate a line short circuit and/or a line interruption in the differentially operated line network if at least one control or controlled variable of the control circuit exceeds a predefined threshold value.