Transformerless Power Over Ethernet System Using Capacitor Isolation

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Solution Overview

Problem

Conventional Power-over-Ethernet (PoE) systems rely on transformers for electrical isolation and power transmission, which can be costly and may introduce noise, limiting efficiency and increasing costs.

Innovation Solution

The use of high-voltage capacitors and DC signal extraction devices replaces transformers in Power-over-Ethernet systems, providing transformerless electrical isolation and efficient power provision, allowing for the extraction and injection of DC signals on wire pairs within the PoE system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If transformers are used for electrical isolation and power transmission in PoE systems, then electrical isolation is achieved, but cost increases and noise is introduced

Engineering Contradiction:

Improveelectrical isolationVSAvoidnoise

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts and removes the transformer component from the PoE system, replacing it with capacitor-based isolation. This eliminates the noise-generating magnetic core while maintaining electrical isolation functionality through high-voltage capacitors connected in series with the power lines.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes the mechanical/magnetic transformer system with an electrical capacitor-based isolation system. Instead of using magnetic fields and physical transformer cores, the invention uses high-voltage capacitors to provide galvanic isolation, thereby eliminating mechanical noise and reducing overall system noise.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If transformers are used for electrical isolation and power transmission in PoE systems, then electrical isolation is achieved, but system cost increases

Engineering Contradiction:

Improveelectrical isolationVSAvoidsystem cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive, bulky transformers with cheaper, compact high-voltage capacitors. The capacitor-based isolation system reduces component cost, assembly complexity, and overall system price while maintaining the essential electrical isolation function required for PoE operation.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

By removing the transformer component entirely and replacing it with a simpler capacitor-based isolation circuit, the patent reduces bill of materials cost, assembly steps, and manufacturing complexity, directly addressing the cost issue.

Inventive Principle:

Principle #2Taking out (Extraction)

3Power

If transformers are used in PoE systems, then power transmission is enabled, but device complexity increases

Engineering Contradiction:

Improvepower transmissionVSAvoidsystem complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent extracts the transformer from the power transmission path and replaces it with high-voltage capacitors and DC signal extraction devices. This simplifies the overall system architecture by removing a complex magnetic component while maintaining power transmission capability through the capacitor-based isolation circuit.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes the complex magnetic transformer system with simpler electrical components (capacitors and DC extraction circuitry), reducing device complexity while preserving the power transmission function. The capacitor-based approach eliminates the need for magnetic core assembly and associated complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 costs and noise, enhancing the efficiency and reliability of PoE systems by eliminating the need for transformers and improving electrical isolation, while maintaining effective power transmission and data communication.

Implementation Method 1

at least one capacitor located in a signal path between the cable and the communication device

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

Each DC signal device is adapted to extract or inject a DC component of a signal on the corresponding wire pair

Methodology Applied

Scientific EffectElectrical signal extraction:

Data Source

PatentUS8132027B2Transformerless power over ethernet system

Publication Date: 2012.03.06 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

In one embodiment, a powered device (PD) (402) has a PHY module (410) and a media access controller (419) (MAC), the PD (402) adapted to connect to power sourcing equipment (PSE) via a cable, (408) where the PD (402) is adapted to communicate with and receive power from the PSE via the cable, in accordance with the Power-over-Ethernet (PoE) standard. The PD (402) extracts (413) from the cable (408) a DC signal used to power the PD without using a transformer. Capacitors (420) located in the signal paths between the MAC (419) and the cable (408) support electrical isolation of the MAC (419).