POE PSE MPS Support Against Voltage Transient Shutdowns
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Solution Overview
Problem
Power over Ethernet (POE) systems falsely shut down powered devices (PDs) due to PSE voltage transients, which cause PDs to internally draw MPS pulses, leading to false disconnection despite the PDs being connected and supplying current.
Innovation Solution
A control circuit measures voltage drops and allows a predetermined number of missed MPS signals before disconnecting the PD, based on the magnitude of the voltage drop, to prevent false shutdowns during PSE voltage transients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PSE monitors MPS current to detect PD disconnection, then the PSE can identify disconnected cables and remove power, but voltage transients cause false detection of disconnection when the PD is actually connected
Solution Approach 1:
The patent introduces an intermediary mechanism by measuring PSE voltage as an additional parameter to distinguish between true disconnection and voltage transient conditions. The control circuit uses voltage information as a mediator to validate whether missed MPS signals are due to actual disconnection or voltage drop, thereby preventing false shutdowns while maintaining accurate connection detection
Solution Approach 2:
The patent changes the detection parameters by incorporating PSE voltage measurement into the connection status determination process. Instead of relying solely on MPS current detection, the system now considers both MPS signals and PSE voltage levels, adjusting the interpretation of MPS misses based on voltage conditions to resolve the false detection problem
2Loss of energy
If the PSE removes power after 400ms without MPS signal, then disconnected cables stop drawing power, but connected PDs experiencing voltage transients are incorrectly shut down
Solution Approach 1:
The patent implements feedback by continuously monitoring PSE voltage and using it to adjust the interpretation of MPS signal misses. The control circuit receives feedback about voltage conditions and uses this information to determine whether to maintain or remove power, creating a closed-loop system that prevents false shutdowns while still identifying truly disconnected cables
Solution Approach 2:
The patent introduces dynamic behavior by making the power removal decision adaptive rather than fixed. Instead of automatically shutting down after 400ms without MPS signals, the system dynamically adjusts its response based on real-time PSE voltage measurements, allowing it to maintain power during voltage transients while still responding to actual disconnections
Data Source
AI summary
An apparatus includes a power-over-Ethernet (POE) interface to be connected to a powered device (PD) over an Ethernet cable and a control circuit. The control circuit is to measure a voltage provided by the apparatus through the Ethernet cable, determine that the voltage has dropped by at least a given voltage change, based on a determination that the voltage has dropped by at least the given voltage change, determine whether or not a predetermined quantity of Maintain Power Signature (MPS) signals have been missed within a given time frame, and, based on a determination that the predetermined quantity of MPS signals has not been missed within the given time frame, determine that the PD is still connected to the apparatus.