Modular Multilevel Converter Ducted Cooling for Outdoor Module Replacement

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Solution Overview

Problem

Existing modular multilevel converters (MMCs) are costly to install and maintain, require large footprints, and necessitate extensive civil engineering for indoor installations, with components needing complete shutdown for maintenance, and outdoor setups face insulation challenges due to environmental conditions.

Innovation Solution

A modular multilevel converter design featuring a duct system with manifolds and detachable connectors for air and fluid conveyance, integrated cooling, and a cable arrangement, allowing individual module replacement and maintenance without full shutdown, and maintaining controlled climate and insulation despite outdoor conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If MMCs are installed indoors with air insulation, then insulation performance is improved, but installation cost and footprint increase

Engineering Contradiction:
Improveinsulation performanceVSAvoidinstallation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The converter station is divided into multiple independent converter cell modules, each with its own enclosure and insulation. This segmentation allows outdoor installation while maintaining insulation performance through modular units rather than requiring a large indoor hall with centralized air insulation.

Inventive Principle:
Principle #1Segmentation

2Area of stationary object

If valve tanks are placed outdoors, then footprint is reduced, but insulation performance deteriorates due to environmental conditions

Engineering Contradiction:
ImprovefootprintVSAvoidinsulation performance
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The system uses multiple independent converter cell modules with individual enclosures instead of large outdoor valve tanks. Each module maintains its own insulation, allowing outdoor placement with reduced footprint while preserving insulation performance through distributed modular architecture.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each converter cell module is provided with an enclosure that serves as an insulating barrier. These enclosures protect the internal components from environmental conditions while maintaining a compact outdoor footprint, replacing the need for large traditional valve tanks.

Inventive Principle:
Principle #30Flexible shells and thin films

3Ease of repair

If complete valve shutdown is performed for maintenance, then repair access is improved, but productivity decreases

Engineering Contradiction:
Improvemaintenance accessVSAvoidsystem availability
Core Design Contradiction:
Ease of repairVSProductivity

Solution Approach 1:

The converter is divided into independent converter cell modules that can be maintained individually. Each module has its own enclosure with detachable connections, allowing technicians to access and repair specific modules without shutting down the entire converter system, thus maintaining productivity while enabling easy repair access.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Individual converter cell modules can be extracted from the system for maintenance while the remaining modules continue to operate. The detachable enclosure connections enable quick removal and replacement of modules, providing maintenance access without requiring complete system shutdown.

Inventive Principle:
Principle #2Taking out (Extraction)

4Reliability

If traditional indoor converter halls are used, then insulation and control are improved, but installation cost and civil engineering requirements increase

Engineering Contradiction:
Improveinsulation performanceVSAvoidinstallation cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The system uses modular converter cell modules with individual enclosures that can be installed outdoors without requiring large indoor converter halls. This eliminates the need for extensive civil engineering while maintaining insulation performance through distributed modular units with detachable connections for easy installation.

Inventive Principle:
Principle #1Segmentation

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

Facilitates easier installation, maintenance, and reduced footprint by enabling individual module replacement and controlled climate within outdoor setups, enhancing efficiency and reducing complexity.

Implementation Method 1

a duct system arranged to convey air from an air-conditioning unit into the enclosures of the plurality of converter cell modules

Methodology Applied
Scientific EffectAir conveyance through ducts: Convection

Implementation Method 2

a heat pipe is installed between each of the submodules and the duct to transfer heat generated in a submodule to the air flowing in the duct using the heat pipe

Methodology Applied
Scientific EffectHeat pipe: Heat Pipe

Data Source

PatentEP4106505B1Modular multilevel converter
Publication Date: 2026.03.18 HITACHI ENERGY LTD
  • EP4106505B1 patent drawingFigure 1
  • EP4106505B1 patent drawingFigure 2
  • EP4106505B1 patent drawingFigure 3

AI summary

A modular multilevel converter (100) is provided. The modular multilevel converter includes at least one valve comprising a plurality of converter cell modules (110) electrically connected to each other, and a duct system (120). A converter cell module includes at least one converter cell and an enclosure (111) in which the at least one converter cell is arranged. The duct system is arranged to convey air from an air-conditioning unit (130) into the enclosures of the plurality of converter cell modules. The duct system includes a first manifold (121) and at least one second manifold (122) fluidly connected to the first manifold. The first manifold is connected to the air-conditioning unit and a second manifold is dedicated for connecting the first manifold to at least some of the plurality of converter cell modules. The enclosure of a converter cell module is fluidly and detachably connected to a second manifold via a duct connector (140) attached to the enclosure of the converter cell module.