Five-level converting device asymmetrical circuit design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multi-level converting devices face challenges with voltage rating and dv/dt issues in medium-voltage and high-voltage systems, limiting their efficiency and economic viability in high-power applications.
Innovation Solution
A five-level converting device is designed with an asymmetrical circuit structure, incorporating a bus capacitor module, switch modules, and flying capacitor modules, which reduces the number of switching units and enhances flexibility and resilience, improving electrical performance compared to traditional three-level technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional three-level technology is used, then device complexity is reduced, but electrical performance deteriorates
Solution Approach 1:
The circuit is segmented into multiple functional modules: first and second switch modules with specific switching units, flying capacitor modules for voltage stabilization, and bus capacitor modules. This modular segmentation enables five-level voltage output while maintaining manageable circuit complexity through systematic organization of components.
Solution Approach 2:
The patent employs asymmetrical circuit configuration where the first and second switch modules have different connectivity patterns, and the flying capacitor modules are selectively connected to different terminals. This asymmetry optimizes the voltage distribution and switching characteristics to achieve superior electrical performance compared to symmetrical three-level topologies.
2Reliability
If more switching units are added to achieve five-level conversion, then electrical performance improves, but ease of operation deteriorates
Solution Approach 1:
The switching units in the first and second switch modules are designed with multi-functional capability, where each switching unit can perform multiple switching functions depending on its state. The flying capacitor modules also serve dual purposes: voltage stabilization and level shifting. This multi-functionality reduces the overall control complexity despite having multiple switching elements.
Solution Approach 2:
The flying capacitor modules act as intermediary elements between the switch modules and the output terminals, mediating the voltage levels and simplifying the control logic. By introducing these intermediate energy storage elements, the direct control burden on switching units is reduced, making the overall system easier to operate.
3Adaptability or versatility
If asymmetrical circuit structure is used, then flexibility and resilience improve, but device complexity increases
Solution Approach 1:
Different parts of the circuit are assigned different connectivity qualities: the first switch module connects to specific terminals while the second switch module connects to others, and flying capacitors are selectively placed. This local differentiation optimizes flexibility and resilience in specific circuit regions without unnecessarily complicating the entire system.
Data Source
AI summary
A five-level converting device includes an AC terminal, a bus capacitor module having a positive terminal, a negative terminal and a neutral terminal, a first switch module and a second switch module. The first switch module includes a bidirectional switching circuit, and the bidirectional switching circuit includes two first switching units reversely connected in series. The second switch module includes two second switching units, two third switching units, two fourth switching units, and two fifth switching units. The two second switching units are cascaded and connected to the two fourth switching units in parallel. The third, the fourth and the fifth switching units are cascaded and are connected to the bus capacitor module in parallel. Two different connection points of the first switch module are connected to the third switching units and fifth switching units through two flying capacitor modules respectively.