Three-Level Inverter With Segmented Bidirectional Switches
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Solution Overview
Problem
Conventional three-level inverter systems cannot continue operation when a semiconductor switch element or diode fails, requiring a parallel redundancy system that increases size and cost, making it unsuitable for applications like uninterruptible power supply systems.
Innovation Solution
A power conversion circuit with a plurality of one-phase switch circuits and bidirectional semiconductor switch circuits that include opening means to isolate failed components, allowing operation to continue as a two-level inverter system using remaining switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a parallel redundancy system is used to maintain operation when semiconductor switch elements fail, then system reliability is improved, but system size and cost increase
Solution Approach 1:
The bidirectional semiconductor switch circuit is segmented into multiple independent switch elements (first bidirectional switch and second bidirectional switch). When one element fails, the other can continue to operate, providing inherent redundancy without requiring a separate parallel system. This segmentation allows the system to maintain functionality while avoiding the size and cost penalties of traditional parallel redundancy configurations.
2Reliability
If a parallel redundancy system is used to maintain operation when semiconductor switch elements fail, then system reliability is improved, but manufacturing cost increases
Solution Approach 1:
The redundancy function is merged into the normal circuit structure by incorporating multiple bidirectional switch elements within the same circuit pathway. Instead of adding separate parallel redundant systems, the redundancy is integrated into the existing circuit architecture, eliminating the need for additional components and reducing manufacturing costs while maintaining reliability.
3Duration of action of stationary object
If conventional three-level inverter operation is maintained after semiconductor switch failure, then operational continuity is improved, but harmful short circuit currents increase
Solution Approach 1:
When a semiconductor switch element fails, the corresponding bidirectional switch is electrically opened to extract and isolate the failed component from the circuit. This prevents harmful short circuit currents from flowing through the failed element while allowing the system to continue operation using the remaining functional switch elements, thus removing the harmful factor while maintaining operational continuity.
Data Source
AI summary
A three-level power conversion circuit includes a plurality of one-phase switch circuits which receive power from direct current power supplies that are connected in series. Each of the one-phase switch circuits includes a semiconductor switch series circuit that is connected in parallel to the direct current power supplies, and also a bidirectional switch and a circuit-opening device that are connected in series between a series connection point of the semiconductor switch series circuit and a series connection point of the direct current power supplies. If a semiconductor element in a bidirectional switch fails, the circuit opening device opens a path along which the main current of the semiconductor element flows, and operation of the inverter is continued as a two-level inverter with the remaining bidirectional switches in a constant off-state.