PLC to PoE Coupler with Galvanic Isolation

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Solution Overview

Problem

In applications such as aircraft, the installation of separate power distribution and communication wiring is costly and weight-intensive, necessitating a solution that combines power distribution and communication systems to reduce wiring requirements.

Innovation Solution

A coupler that interfaces between a power line communication (PLC) bus and power-over-Ethernet (POE) devices, providing pass-through transmission of power and PLC signals, over-current protection, and programmable current limits, while converting between PLC and Ethernet protocols to share conductors and isolate faults.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate power distribution and communication wiring are installed, then system reliability and independence are improved, but weight, installation cost, and maintenance cost increase

Engineering Contradiction:
Improvesystem reliabilityVSAvoidwiring weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent combines power distribution and communication functions into a single wiring infrastructure by using a PLC bus that carries both power and data signals. The coupler device integrates multiple functions (PLC interface, POE interface, isolation, current limiting) into one unit that enables both power and communication over the same conductors, thereby reducing total wiring weight while maintaining system reliability through functional integration and electrical isolation.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The coupler device serves multiple functions simultaneously: it provides electrical isolation between PLC and POE networks, limits current to protect POE devices, interfaces between different communication protocols (PLC and Ethernet), and enables both power and data transmission. This multi-functionality allows a single device to replace what would traditionally require separate dedicated components and wiring.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If separate power distribution and communication wiring are installed, then system independence is improved, but installation cost and maintenance cost increase

Engineering Contradiction:
Improvesystem independenceVSAvoidinstallation cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent reduces installation cost by merging power and communication into a single PLC bus infrastructure. The coupler device enables this consolidation while maintaining system independence through galvanic isolation, which prevents electrical interference and fault propagation between the power and communication networks, thereby preserving system independence without requiring separate wiring.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The coupler acts as an intermediary device that bridges the PLC bus and POE devices. It provides galvanic isolation that maintains electrical independence between the two networks while enabling functional integration. This intermediary approach allows cost reduction through shared wiring while preserving the independence and reliability of both power and communication systems.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Quantity of substance

If power and communication are combined over the same conductors, then wiring requirements are reduced, but electrical interference and fault propagation risk increase

Engineering Contradiction:
Improvewiring requirementsVSAvoidelectrical interference
Core Design Contradiction:
Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent merges power and communication into the same PLC bus conductors, reducing wiring requirements. To address the risk of electrical interference and fault propagation, the coupler device incorporates galvanic isolation that electrically separates the PLC and POE networks while allowing signal and power transfer, thereby eliminating interference paths and fault propagation routes.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The coupler serves as an isolated intermediary between the PLC bus and POE devices. The galvanic isolation physically breaks the electrical connection between the two networks, preventing electrical interference and fault propagation while still enabling functional communication and power transfer through the isolation barrier. This mediator approach allows conductor sharing without the harmful effects of direct electrical connection.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Reliability

If a coupler provides over-current protection and current limiting, then device safety is improved, but device complexity increases

Engineering Contradiction:
Improvedevice safetyVSAvoidcoupler complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent integrates multiple protection and control functions (over-current protection, current limiting, galvanic isolation, protocol conversion) into a single coupler device. While this increases device complexity, it consolidates what would otherwise require multiple separate components, and the integrated approach improves reliability by ensuring coordinated protection across all functions within a single unified device.

Inventive Principle:
Principle #5Merging (Combining)

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

This solution reduces wiring weight, installation, and maintenance costs by enabling multiple POE nodes to be coupled to a PLC bus, providing efficient power distribution and communication while protecting against over-currents and isolating faults.

Implementation Method 1

a transformer having a first winding capacitively coupled to the PLC bus by a first capacitor and a second capacitor

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3128679B1Coupler for power line communication and power-over-ethernet
Publication Date: 2019.08.07 THE BOEING CO
  • EP3128679B1 patent drawingFigure 1
  • EP3128679B1 patent drawingFigure 2
  • EP3128679B1 patent drawingFigure 3

AI summary

A coupler (130) is provided. The coupler (130) includes a power line (110), a PLC-to-Ethemet converter (226), a first transformer (228), and a power sourcing circuit (218). The power line (110) is coupled between a first connector (202) and a second connector (204). The power line (110) is configured to conduct PLC signals. The PLC-to-Ethernet converter (226) is configured to convert between the PLC signals and Ethernet signals. The first transformer (228) is coupled between the PLC-to-Ethernet converter (226) and a third connector (206). The first transformer (228) is configured to condition the Ethernet signals for power-over-Ethernet transmission. The power sourcing circuit (218) is coupled to the power line (110) and configured to provide power to the first transformer (228).