Shared ZVT Auxiliary Circuit for Soft-Switched Multi-Level Converters
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Solution Overview
Problem
Conventional ZVT auxiliary circuits for multi-level boost converters require additional components for each switching stage, increasing the size, weight, and complexity, while also leading to higher switching losses and heat generation due to hard-switching issues.
Innovation Solution
A simplified ZVT auxiliary circuit design for a multi-level boost converter, featuring two solid-state auxiliary switches connected in series across an input voltage and inductor, with a single auxiliary inductor shared between two switching stages, eliminating the need for diodes and reducing overall component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ZVT auxiliary circuits are used for each switching stage in multi-level boost converters, then soft-switching performance is improved, but device complexity and component count increase significantly
Solution Approach 1:
The patent merges the auxiliary circuits of multiple switching stages into a single shared auxiliary circuit. Instead of providing separate ZVT auxiliary circuits for each switch in the multi-level boost converter, the invention uses one common auxiliary circuit that serves all switching stages, thereby reducing component count and complexity while maintaining soft-switching performance across all stages.
Solution Approach 2:
The shared auxiliary circuit is designed to perform multiple functions simultaneously - it provides soft-switching support for all switching stages across different voltage levels. The auxiliary circuit universally serves the entire multi-level converter system rather than being dedicated to a single switching stage, achieving multi-functionality with a single circuit design.
2Volume of moving object
If higher switching frequencies are used to reduce component size, then converter size is reduced, but switching losses and heat generation increase
Solution Approach 1:
The auxiliary circuit performs preliminary action by pre-charging or pre-discharging the parasitic capacitances of the main switches before they are switched. This preliminary action ensures that the main switches turn on or off when the voltage across them is already zero or near-zero, enabling soft-switching conditions and allowing high-frequency operation without excessive switching losses.
3Device complexity
If hard-switching operation is used to simplify circuit design, then device complexity is reduced, but switching losses and reliability deteriorate
Solution Approach 1:
The auxiliary circuit acts as an intermediary between the main power switches and the power source/load. It mediates the switching process by providing a path for resonant current flow that eliminates voltage spikes and current shocks during switching transitions, thereby protecting the main switches and improving reliability without significantly complicating the overall circuit design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enables high-frequency switching with reduced noise and size, maintaining efficiency and reliability while minimizing cooling requirements, achieving improved power density and miniaturization without increasing losses or temperature.
Implementation Method 1
an auxiliary inductor Laux connected at one end between the first and second solid state auxiliary switches, the other end being arranged to be connected between two switching stages
Data Source
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AI summary
A zero voltage transition, ZVT, auxiliary circuit for a multi-level power converter, the ZVT auxiliary circuit comprising: first and second solid state auxiliary switches connected in series across a series connection of an input voltage and an input inductor, and an auxiliary inductor Laux connected at one end between the first and second solid state auxiliary switches, the other end being arranged to be connected between two switching stages of the multi-level power converter, in use.