Galvanic Isolation Interface for PoE Power Transfer

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Solution Overview

Problem

As the complexity of powered devices (PDs) in Power over Ethernet (PoE) systems increases, so does the power requirement, posing challenges in efficiently managing power distribution and maintaining electrical isolation between PD subsystems while ensuring adequate power supply and communication.

Innovation Solution

A system comprising a powered device with multiple electrically isolated PD subsystems and an interface that allows communication and power transfer between them, using a power sourcing equipment (PSE) connected via a standard twisted-pair Ethernet cable, enabling power transfer while maintaining electrical isolation and reporting underpowered conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple PD subsystems are electrically isolated to ensure safety and independence, then reliability is improved, but power transfer capability deteriorates

Engineering Contradiction:
Improveelectrical isolationVSAvoidpower transfer
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

A galvanic isolation interface is introduced as an intermediary component between electrically isolated PD subsystems. This interface uses galvanically isolated communication circuits to enable power transfer information exchange while maintaining electrical isolation, thus resolving the contradiction between reliability through isolation and power transfer capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If power is transferred between isolated PD subsystems, then power distribution efficiency is improved, but electrical isolation is compromised

Engineering Contradiction:
Improvepower distribution efficiencyVSAvoidelectrical isolation
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The galvanic isolation interface acts as a mediator that enables power distribution coordination between isolated subsystems without compromising their electrical isolation. It allows the system to achieve high power distribution efficiency while maintaining the reliability benefits of electrical isolation through its isolated communication mechanism.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If complex power management is implemented to handle multiple isolated subsystems, then power distribution capability is improved, but device complexity increases

Engineering Contradiction:
Improvepower distribution capabilityVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The galvanic isolation interface enables subsystems to autonomously manage their own power status and communicate power transfer needs without requiring complex centralized control. Each subsystem can independently detect power conditions and initiate power transfer requests, reducing overall system complexity while maintaining high adaptability.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system implements feedback mechanisms where subsystems continuously report their power status and receive power transfer decisions. This feedback loop enables intelligent power distribution across multiple isolated subsystems without requiring complex predetermined control logic, thus improving adaptability while managing complexity.

Inventive Principle:
Principle #23Feedback

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 effectively manages power distribution by allowing power transfer between isolated PD subsystems, ensuring each receives sufficient power, and reduces the need for filtering, thereby enhancing the reliability and efficiency of PoE systems.

Implementation Method 1

an interface connecting the first PD subsystem and the second PD subsystem... transfer power to the second PD subsystem through the interface

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP2225850B1Facilitating communication and power transfer between electrically-isolated powered device subsystems
Publication Date: 2015.09.16 CISCO TECHNOLOGY INC
  • EP2225850B1 patent drawingFigure 1~2
  • EP2225850B1 patent drawingFigure 3~4
  • EP2225850B1 patent drawingFigure 5A~5B

AI summary

A system employing power over Ethernet (PoE) technology may include at least one powered device and power sourcing equipment (PSE). The powered device may include a first powered device (PD) subsystem and a second powered device (PD) subsystem that is electrically isolated from the first PD subsystem. The powered device may also include an interface connecting the first PD subsystem and the second PD subsystem. The PSE may be operable to provide power to one or more of the PD subsystems through a link connecting the PSE to the powered device. Also, the first PD subsystem may be operable to receive a communication from and transfer power to the second PD subsystem through the interface while maintaining the electrical isolation.