PoE Powered Device Power Forwarding via Daisy-Chain
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Solution Overview
Problem
Power-over-Ethernet (PoE) systems face inefficiencies in lighting applications due to high overhead in communication and processing for low-complexity loads and the limitations of star-based network topology, leading to increased cable lengths and installation complexities in serially connected systems.
Innovation Solution
Implementing a powered device with two Ethernet sockets that enable power forwarding in a daisy-chained configuration, allowing for reduced cable lengths and thickness, and using power switching units to manage power negotiation and distribution, ensuring compatibility with existing PoE standards like IEEE 802.3af and IEEE 802.3at.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If PoE systems use star-based network topology for lighting applications, then power distribution is simplified, but cable lengths and installation complexities increase in serially connected systems
Solution Approach 1:
The patent introduces an intermediary powered device that acts as a power forwarding node in the daisy-chained lighting system. This intermediary device receives power from one port and forwards it through another port, enabling serial power distribution without requiring the PSE to be at the beginning of the entire chain. This resolves the contradiction by allowing simplified power distribution through intermediate nodes while maintaining reasonable cable lengths for each segment.
Solution Approach 2:
The patent segments the power distribution function across multiple powered devices in the daisy-chain, rather than requiring a single centralized PSE. Each powered device can independently forward power to subsequent devices, dividing the overall power distribution task into manageable segments. This allows the system to achieve simplified power distribution at each segment while keeping individual cable lengths reasonable.
2Ease of operation
If PoE systems use star-based network topology, then power negotiation is straightforward, but installation costs and complexities increase for serially connected lighting systems
Solution Approach 1:
The patent enables powered devices to autonomously negotiate and forward power without requiring complex centralized control for each connection. Each powered device in the daisy-chain independently performs power negotiation with its upstream neighbor and automatically configures power forwarding to downstream devices. This self-service approach maintains straightforward power negotiation while dramatically simplifying installation, as devices can be connected in sequence without complex configuration.
3Length of stationary object
If powered devices forward power in daisy-chained configuration, then cable lengths and thickness are reduced, but power management complexity increases
Solution Approach 1:
The patent designs powered devices with universal power switching units that can operate in multiple modes: receiving power, forwarding power, and consuming power. The same hardware infrastructure supports both traditional star-based PoE and the new daisy-chained power forwarding mode. This multi-functionality allows reduced cable lengths in daisy-chain configurations without significantly increasing power management complexity, as the same components handle different operational modes.
4Ease of manufacture
If powered devices enable power forwarding, then installation costs are reduced, but risk of inrush currents increases
Solution Approach 1:
The patent incorporates preliminary anti-action by implementing power switching units that control the timing and sequence of power forwarding. Before a powered device forwards power to downstream devices, the switching unit ensures proper power negotiation and detection completes first. This preliminary control prevents inrush currents by ensuring downstream devices are ready to receive power before it is supplied, thereby reducing installation costs without introducing harmful inrush current effects.
Data Source
AI summary
The present invention relates to a powered device (331a, 331b, 531a) with two interfacing connections. The powered device (331a, 331b, 531a) comprises power switching units (350a, 350b, 550a1, 550a2) for forwarding the data signal as well the power received on the input to the output. Forwarding may be based on a detection of the powering state of the PD. In another embodiment, the Power-over-Ethernet input/output ports function bi-directionally, thereby allowing the user to daisy-chain devices in any direction. As power switching units, relays or solid-state power switches may be used.