Triangle Topology Multi-Level Converter Reducing Component Count
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Solution Overview
Problem
Existing multi-level inverters face challenges with large volume, high cost, and increased on-state losses due to the number of diodes and switches, particularly when extended to more levels, and require a large number of independent power supplies or flying capacitors.
Innovation Solution
A multi-level converter with a triangle topology is introduced, utilizing n capacitors and 2n switching tubes to form n layers of circuits, where switching tubes are controlled in a complementary manner to achieve efficient output levels without the need for flying capacitors, thereby reducing system volume and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the diode-clamped topology is extended to more levels, then the output voltage levels increase, but the number of diodes increases sharply which increases volume and cost
Solution Approach 1:
The converter is divided into multiple independent layers, where each layer k includes a k-th capacitor, (2k-1)-th switching tube, and 2k-th switching tube. This segmentation allows the system to achieve n-level output by stacking n layers, with each layer contributing one capacitor to the series connection, thereby reducing the overall complexity compared to traditional topologies
Solution Approach 2:
The patent transitions from traditional planar circuit layouts to a three-dimensional stacked architecture where layers are vertically arranged. Each layer is connected in series to form the complete converter, utilizing the vertical dimension to accommodate multiple capacitors and switching tubes without proportionally increasing horizontal footprint, thus improving power density
2Power
If the number of switching elements is increased to achieve more output levels, then the output voltage levels increase, but the on-state loss of the system increases
Solution Approach 1:
Each layer uses only 2 switching tubes instead of the conventional 3 or more, implementing a minimal sufficient configuration. This partial action approach reduces the total number of switching elements to exactly 2n for an n-level converter, minimizing on-state losses while still achieving the desired voltage multiplication through the series connection of capacitor voltages
3Power
If traditional multi-level inverter topologies are used, then output voltage levels can be achieved, but flying capacitors are required which increase volume and cost
Solution Approach 1:
The capacitors in each layer serve multiple functions: they act as energy storage elements, voltage reference sources, and level-shifting components simultaneously. The k-th capacitor not only stores energy but also provides the voltage reference for the k-th layer's switching operations and contributes to the overall output voltage through series connection, eliminating the need for separate flying capacitors
Solution Approach 2:
The patent merges the functions of traditional flying capacitors with the main DC-link capacitors. Each capacitor in the series connection serves both as part of the DC voltage source and as the level-defining element for its corresponding layer, consolidating multiple functions into single components and reducing overall system complexity
Data Source
AI summary
The present disclosure provides a multi-level converter with triangle topology and control method thereof, related to the technical field of multi-level converters. In the converter, n DC capacitors connected in series form a vertical edge of a triangle and are as a DC bus, n switching tubes connected in series form a bevel edge of the triangle, switching tubes each connected between a neutral point of the DC bus corresponding to each layer and a point for connecting the switching tube on the bevel edge form a horizontal edge. Each time the layer is expanded by one, the number of levels increases by one. When a voltage across each capacitor is E, an AC output terminal Xn may output a total of n+1 levels.