Daisy-Chained PoE Sensor Units for Redundant Power Delivery
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Solution Overview
Problem
Conventional Power over Ethernet (PoE) systems in a star topology require long, heavy cables for distant sensors, leading to weight, size, and reliability issues, especially in distributed sensor systems like those in vehicles, where reducing cable length and weight is necessary.
Innovation Solution
A distributed sensor network with daisy-chained sensor units connected via Ethernet cables, where power and data are intelligently passed from unit to unit, providing redundant power and network connectivity, and featuring automatic fault detection and isolation using a 'Hot-Swap' controller and two levels of over-current protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PoE star topology is used to power distant sensors, then power delivery is achieved, but cable length and weight increase significantly
Solution Approach 1:
The patent segments the power delivery system into multiple daisy-chained sensor units, where each unit acts as both a powered device and a power source for the next unit. This segmentation allows power to be delivered incrementally along the daisy chain, eliminating the need for long cables from the central switch to each distant sensor, thus reducing overall cable weight while maintaining reliable power delivery.
Solution Approach 2:
Adjacent sensor units serve as intermediaries in the power delivery path. Each sensor unit receives power from its upstream neighbor and forwards it to its downstream neighbor, acting as a mediator that enables power delivery to distant sensors without requiring long cables from the central switch. This intermediary function resolves the contradiction by distributing power delivery responsibilities across multiple nodes.
2Reliability
If conventional PoE star topology is used for distant sensors, then power supply is provided, but system size and complexity increase
Solution Approach 1:
Each sensor unit is designed with multi-functionality, serving simultaneously as a powered device (receiving power and data), a power source (providing power to adjacent units), and a network switch (providing Ethernet connectivity). This universality simplifies the overall system architecture by eliminating the need for separate power supplies and switches at each sensor location, reducing system complexity while maintaining reliable power supply.
Solution Approach 2:
The patent merges the functions of power consumption, power delivery, data processing, and network switching into a single integrated sensor unit. By combining these previously separate functions into one device, the system complexity is reduced while power supply reliability is maintained through the daisy-chained architecture where multiple units can provide power if one fails.
3Weight of stationary object
If daisy-chained sensor units are used, then cable length and weight are reduced, but power delivery distance limitations may arise
Solution Approach 1:
The daisy-chained architecture enables continuous power delivery action across multiple sensor units. Each unit in the chain receives power from its upstream neighbor and immediately forwards it to its downstream neighbor, creating an unbroken chain of power transmission. This continuity allows power to be delivered over extended distances through multiple short cable segments rather than a single long cable, effectively overcoming distance limitations while keeping individual cable lengths short and lightweight.
4Device complexity
If single power path is used in PoE system, then system simplicity is maintained, but reliability decreases due to single point of failure
Solution Approach 1:
The patent changes the topological parameter of the power delivery system from a single-path star topology to a multi-path daisy-chain topology with redundant pathways. In this configuration, power can flow through multiple different paths to reach any given sensor unit (e.g., through upstream or downstream neighbors in the daisy chain), providing redundancy without significantly increasing system complexity. This parameter change enables the system to tolerate single points of failure while maintaining operational reliability.
Data Source
AI summary
According to one aspect, embodiments of the invention provide a method for providing power to a distributed sensor system, the method comprising providing power from at least one port of an interface unit to a first port of a first sensor unit of at least one of a plurality of sensor strings, powering up the first sensor unit, forwarding power from a second port of the first sensor unit to a first port of a second sensor unit of the at least one of the plurality of sensor strings, powering up the second sensor unit, monitoring the plurality of sensor strings for a fault condition, and in response to detecting a fault condition in a first sensor string of the plurality of sensor strings, providing power from a second one of the plurality of sensor strings to the first sensor string.