Electrolysis Plant AC Intermediate Circuit for Galvanic Isolation

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Solution Overview

Problem

Existing electrolysis plants face challenges in connecting directly to renewable energy sources like wind or photovoltaic plants without causing interference, particularly due to high-frequency stray currents and ground loops, which can damage sensitive electrolysis cells and lead to voltage losses.

Innovation Solution

An electrolysis plant with a circuit arrangement featuring an AC intermediate circuit that includes an inverter and a transformer, allowing direct connection to a DC source while providing galvanic decoupling, preventing ground loops and electromagnetic interference, and enabling flexible voltage adaptation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an electrolysis plant is directly connected to renewable energy sources, then independence from the public grid and cost-effectiveness are improved, but high-frequency stray currents and ground loops cause interference and damage to electrolysis cells

Engineering Contradiction:

Improveindependence from public gridVSAvoidhigh-frequency stray currents and ground loops

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an AC intermediate circuit as a mediator between the DC source and the electrolysis plant. This intermediate circuit includes an inverter that converts DC to AC, and a rectifier that converts AC back to DC. The intermediary AC circuit with galvanic decoupling prevents direct transmission of high-frequency stray currents and ground loops from the DC source to the electrolysis cells, thereby resolving the interference problem while maintaining grid independence.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If line-commutated rectifiers are used for industrial-scale electrolysis, then direct current is provided reliably, but harmonics are generated that load the AC and DC grids

Engineering Contradiction:

Improvedirect current supplyVSAvoidharmonics

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The AC intermediate circuit acts as a mediator that decouples the harmonics generated by line-commutated rectifiers from the DC grid and AC grid. The inverter and rectifier in the intermediate circuit process the power electronically, preventing harmonic propagation to the external grids while maintaining reliable DC supply to the electrolysis plant.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the direct mechanical/electrical connection with line-commutated rectifiers with an electronic conversion system consisting of inverter and rectifier. This substitution eliminates the direct harmonic injection into the grids by using electronic switching and galvanic decoupling, thereby reducing harmonic pollution while maintaining reliable DC supply.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Stability of the object's composition

If the electrolysis plant operates with public grid power, then stable operation is achieved, but the proportion of green hydrogen is limited by the power mix

Engineering Contradiction:

Improveoperation stabilityVSAvoidgreen hydrogen proportion

Core Design Contradiction:

Stability of the object's compositionVSLoss of substance

Solution Approach 1:

The AC intermediate circuit enables the electrolysis plant to operate stably with independent DC sources such as renewable energy systems. By providing galvanic decoupling and voltage adaptation, the intermediate circuit ensures stable operation without requiring connection to the public grid, thereby enabling 100% green hydrogen production when paired with renewable energy sources.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 configuration ensures interference-free operation, reduces stray currents, and allows for efficient production of green hydrogen using renewable energy independently of the public grid, with compact and cost-effective design.

Implementation Method 1

provides galvanic decoupling, preventing ground loops and electromagnetic interference

Methodology Applied

Scientific EffectGalvanic decoupling: Electromagnetic Induction

Implementation Method 2

circuit arrangement featuring an AC intermediate circuit that includes an inverter and a transformer

Methodology Applied

Scientific EffectElectrical energy conversion: Electromagnetic Induction

Implementation Method 3

electrolysis plant is an apparatus that brings about a conversion of substances with the aid of electrical current (electrolysis)

Methodology Applied

Scientific EffectElectrolysis: Electrolysis

Data Source

PatentUS20250279726A1Electrolysis plant and plant network comprising an electrolysis plant and a renewable energy plant

Publication Date: 2025.09.04 SIEMENS ENERGY GLOBAL GMBH & CO KG

AI summary

An electrolysis plant includes an electrolyzer and a circuit assembly which has an input for connecting to an external DC source and an output connected to the electrolyzer. The circuit assembly has a transformer with an inverter connected on the primary side and a rectifier connected on the secondary side, such that a direct current can be supplied to the electrolyzer. There is also described a plant network with a electrolysis plant and a renewable energy plant that is directly connected to the electrolysis plant.