Mid-Span Power Injection Device for Dual PoE Sourcing

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Solution Overview

Problem

Existing Power-over-Ethernet (PoE) systems face limitations in delivering power over Gbit Ethernet cables due to signal degradation caused by transformers, which reduces cable length and increases costs, and there is a need for efficient power distribution to Ethernet devices located remotely without access to traditional power sources.

Innovation Solution

A mid-span power injection device (MSPID) using capacitors and center-tapped chokes to isolate and deliver direct current (DC) power to specific Ethernet devices over Ethernet data paths, allowing for independent power sourcing and minimizing signal interference, compliant with IEEE PoE 802.3at protocol.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If transformers are used to inject DC power into Gbit Ethernet cables, then power can be delivered to remote devices, but signal integrity deteriorates due to leakage inductance and interwinding capacitance

Engineering Contradiction:

Improvepower delivery capabilityVSAvoidsignal integrity

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent divides the power injection function into separate components for each twisted pair, with individual capacitors and chokes for each pair. This segmentation isolates the power injection circuits, reducing mutual interference and maintaining signal integrity while enabling power delivery to multiple devices

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces capacitors as intermediary elements that couple DC voltage to the twisted pairs while blocking AC data signals from entering the power supply circuitry. This intermediary component allows simultaneous power injection and data transmission without degradation

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by moving object

If transformers are used for power injection, then DC power can be supplied to Ethernet devices, but cable length must be reduced due to signal degradation

Engineering Contradiction:

Improvepower injection capabilityVSAvoidallowable cable length

Core Design Contradiction:

Use of energy by moving objectVSLength of stationary object

Solution Approach 1:

The patent replaces traditional transformer-based power injection with a capacitor-choke circuit configuration. This substitution eliminates the signal-degrading effects of transformer leakage inductance and interwinding capacitance, allowing extended cable lengths while maintaining both power delivery and signal integrity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If multiple devices are powered over a single Ethernet cable, then power distribution efficiency improves, but power isolation between devices becomes difficult to achieve

Engineering Contradiction:

Improvepower distribution efficiencyVSAvoidpower isolation complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent assigns dedicated capacitors and chokes to each twisted pair, creating isolated power injection circuits for each device. This segmentation enables efficient power distribution to multiple devices while maintaining simple power isolation through the inherent separation of circuit components

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements power injection with different characteristics for each twisted pair, allowing each device to receive optimized power while maintaining isolation. Each pair has its own capacitive coupling and choke configuration, enabling localized power management

Inventive Principle:

Principle #3Local quality

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 and efficient power distribution to multiple Ethernet devices over longer distances without degrading signal integrity, reducing installation costs, and allowing for flexible placement of devices without traditional power sources.

Implementation Method 1

The Ethernet data path includes at least one capacitor adapted to pass a data signal between the first and second powered devices and block DC power

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Implementation Method 2

The mid-span power injection device includes a first choke adapted to pass the first DC power from the first power sourcing equipment to the first powered device

Methodology Applied

Scientific EffectInductive filtering: Inductor

Data Source

PatentUS11764983B2Dual sourcing power over ethernet on a single data path

Publication Date: 2023.09.19 CRESTRON ELECTRONICS INC

AI summary

Described herein is a data communication system using power over Ethernet (PoE) for power distribution, comprising a first and second powered device (PD), each of which is adapted to communicate with each other through an Ethernet data path (EDP) and is further adapted to receive direct current (DC) power using a PoE protocol, and a mid-span power injection device (MSPID) adapted to provide a communications interface such that data communications passes through the MSPID to and from each of the PDs, and wherein the MSPID is further adapted to provide a first DC power to only the first PD using the EDP, and to provide a second DC power to only the second PD using the EDP.