Midspan PSE Power-Off Detection for PoE Device Restart
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Solution Overview
Problem
High-end devices connected to PoE switches, such as PTZ cameras, require additional power that cannot be interrupted by disabling the PoE switch due to midspan's continuous power delivery, leading to challenges in powering off and restarting these devices.
Innovation Solution
A PSE device with control circuitry and transformers to detect power discontinuation from the PoE switch, using a low-pass filter to prevent false detections and control power supply switches to safely shut off and restart devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a midspan PSE device is used to power high-end devices requiring more power than PoE switches can deliver, then the power delivery capability is improved, but the ability to power off the device by disabling the PoE switch port is lost
Solution Approach 1:
The control circuitry continuously monitors the power input from the PoE switch and detects when power is discontinued. This feedback mechanism enables the midspan to automatically respond to PoE switch port disabling events by cutting off power to the connected device, thereby restoring the power off capability without requiring manual intervention or changing the external power source configuration.
Solution Approach 2:
The control circuitry acts as an intermediary between the PoE switch and the external power source. It receives power from both sources, monitors the PoE power status, and uses this information to control the power supply from the external source to the connected device. This intermediary function allows the system to coordinate between multiple power sources and maintain proper device power management.
2Ease of operation
If the PSE device continuously monitors power from the PoE switch to enable proper power off detection, then the device control capability is improved, but false detections due to brief power glitches may occur
Solution Approach 1:
The control circuitry is pre-configured with a detection mechanism that monitors power continuity from the PoE switch. By having this detection capability in place beforehand, the system can distinguish between intentional power disconnection (device shutdown) and temporary power fluctuations (glitches), enabling accurate power off detection without false positives.
Solution Approach 2:
The control circuitry monitors power parameters over time and uses temporal characteristics to differentiate between genuine power disconnection events and transient glitches. By analyzing the duration and pattern of power interruptions rather than reacting to instantaneous changes, the system achieves reliable detection while avoiding false triggers from brief power fluctuations.
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 reliable power-off and restart of high-end devices by accurately detecting power availability and discontinuation, preventing false power-off signals from brief glitches.
Implementation Method 1
The control circuitry may be connected to the plurality of primary windings of the input transformer via a voltage detector
Implementation Method 2
The PSE device may comprise an input transformer connected to the first input port, an output transformer connected to the output port
Implementation Method 3
The control circuitry may be connected to a power supply switch arranged along the power supply path
Data Source
Figure 1a
Figure 1b
Figure 2
AI summary
A power sourcing equipment, PSE, device for controlling delivery of electric power to a powered device, PD, connected to the PSE device comprises a first input port for reception of input data and electric power from a power over Ethernet, PoE, device such as a PoE switch, a second input port for reception of electric power from a power source other than the PoE device and an output port for provision of the input data received at the first input port and the electric power received at the second input port to the PD. The PSE device further comprises control circuitry that is configured to determine a discontinuation of reception of electric power from the PoE device and configured to, in response to a determination of a discontinuation of reception of electric power from the PoE device, control discontinuation of provision of the electric power to the PD.