Delta Multilevel Converter Using Half-Bridge Submodule Groups
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Solution Overview
Problem
The transition from centralized to decentralized power generation in electrical power supply networks has created a need for reactive power output, which existing technologies struggle to address efficiently, particularly due to high development and production costs associated with two-polarity submodules used in multilevel converters.
Innovation Solution
A multilevel converter assembly and method utilizing three module branches in a delta circuit, where each branch contains submodules that can connect electrical energy storage units into a series circuit at a single polarity, eliminating the need for two-polarity submodules and reducing costs by using half-bridge submodules, allowing for controlled output of reactive power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two-polarity submodules (full-bridge submodules) are used in multilevel converters, then the converter can generate both positive and negative voltages, but the development and production costs are comparatively high
Solution Approach 1:
The module branch is segmented into two groups of submodules: first group submodules that connect energy storage units at a first polarity, and second group submodules that connect energy storage units at a second polarity. This segmentation allows each submodule type to be specialized for a single polarity, reducing manufacturing complexity and cost while maintaining the overall capability to generate both positive and negative voltages through the combination of groups
Solution Approach 2:
Both first group and second group submodules use the same half-bridge circuit design with two electronic switching elements, making the submodule design universal and interchangeable. The multi-functionality is achieved by having the two groups work together in sequence, where each group handles one polarity, thereby reducing development costs through design standardization while maintaining full voltage polarity generation capability
2Ease of manufacture
If half-bridge submodules with single-polarity connection are used, then development and production costs are reduced, but the ability to generate both positive and negative voltages must be maintained through alternative configurations
Solution Approach 1:
The converter is divided into module branches containing two groups of submodules, where each group is responsible for one polarity. This segmentation simplifies the individual submodule design to half-bridge configurations while the group-level organization manages the overall polarity switching, effectively distributing the complexity from the submodule level to the module branch level
Solution Approach 2:
The converter dynamically switches between first group and second group submodules depending on the required voltage polarity. The control system activates appropriate groups in real-time, allowing the system to adapt its configuration dynamically rather than requiring complex static designs, thereby reducing device complexity while maintaining operational flexibility
3Productivity
If decentralized power generation plants replace centralized power plants, then energy distribution is improved, but reactive power provision becomes insufficient
Solution Approach 1:
The multilevel converter assembly enables decentralized power generation plants to self-provide reactive power to the network. By integrating this converter at the decentralized plant level, each plant becomes self-sufficient for reactive power needs, eliminating the dependency on centralized power plants for reactive power provision while maintaining improved energy distribution from the decentralized architecture
Data Source
AI summary
An assembly has a multilevel converter for outputting reactive power to a power supply network. The multilevel converter contains three module branches arranged in a delta circuit. Each module branch contains a plurality of submodules in an electrical series circuit. Each module branch contains a first group of the submodules and a second group of the submodules. The submodules of the first group each contain a first electrical energy storage unit, a first electronic switching element and a second electronic switching element. The first electronic switching element and the second electronic switching element are arranged so that the first electrical energy storage unit is connected into the series circuit at a first polarity.