Multilevel Converter Crosswise Coupling Topology
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Solution Overview
Problem
Conventional multilevel power source converters, such as cascaded H-bridge converters, become bulky and costly when the number of levels exceeds three due to the large number of active and passive components required, making them inefficient and expensive for high-level power conversion in renewable energy systems.
Innovation Solution
A novel multilevel converter topology is introduced, where each phase consists of cascaded basic units with separate and electrically isolated DC sources, and adjacent units are crosswise coupled, reducing the number of switching elements while maintaining high efficiency and generating high-quality waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cascaded H-bridge converter topology is used to achieve high voltage levels, then the converter can generate high-quality waveforms, but the number of active and passive components increases significantly making the device bulky and costly
Solution Approach 1:
The converter is divided into multiple independent basic units, each capable of operating autonomously. Each basic unit contains minimal components (two switching elements and one DC source) and can generate a portion of the total voltage levels through crosswise coupling with other units, thereby reducing the overall component count while maintaining high voltage level capability.
Solution Approach 2:
Multiple basic units are nested in a cascaded configuration where each unit contributes to the overall voltage synthesis. The crosswise coupling allows units to be arranged in a compact nested structure, where the output of one unit feeds into the input of another, achieving high voltage multiplication with minimal incremental components.
2Power
If the number of voltage levels is increased beyond three in conventional topology, then the power conversion capability is improved, but the converter becomes bulky and costly due to large number of components
Solution Approach 1:
Each basic unit is designed to be multi-functional, serving both as a voltage source and as a switching element for waveform generation. The same components within each unit perform multiple functions: the DC source provides voltage, while the two switching elements simultaneously control power flow and generate voltage levels, eliminating the need for separate dedicated components for each function.
Solution Approach 2:
Multiple basic units are merged through crosswise coupling to achieve high voltage levels. Instead of adding independent H-bridge modules that each require four switching elements, the invention merges units that share switching elements through cross-coupling, where the switching elements of adjacent units are electrically connected in a crosswise pattern, reducing redundant components.
3Reliability
If conventional cascaded H-bridge topology is used, then DC to AC conversion function is achieved, but the converter becomes inefficient and expensive for high-level power conversion
Solution Approach 1:
The converter is segmented into independent basic units that can be manufactured and tested separately before assembly. This modular segmentation reduces manufacturing complexity and cost, as each unit requires fewer components and simpler assembly procedures compared to conventional H-bridge modules, while maintaining reliable DC to AC conversion functionality.
Data Source
AI summary
A multilevel converter includes at least one phase each including several cascaded basic units each including a first switching element, a second switching element, and a separate and electrically isolated DC source (SDCS). The SDCS is electrically coupled between the first switching element and the second switching element in each basic unit. Each of the adjacent pairs of the basic units are electrically crosswise coupled together by electrical coupling of the first switching element of a first basic unit of the two adjacent basic units to the second switching element of a second basic unit of the two adjacent basic units, and electrically coupling the second switching element of the first basic unit to the first switching element of the second basic unit.