Filter Reduction and Improved ZVT Circuit for Transformer-less, High Conversion Ratio (TL-HCRC) Converters


With the advent of fast switching devices with silicon carbide and gallium nitride materials, the frequencies in power converters have increased dramatically to achieve high power densities. To achieve these high densities transformer-less solutions have become a trend in high conversion ratio applications such as renewable energy. However, power semiconductor devices in conventional transformer-less high ratio converters have both high voltage stress and high current stress. This results in significant switching and conduction losses, accruing to efficiency degradation, large heat sinks, and multiple filters. High conversion ratio applications are in increasing need of better transformer-less solutions.

Invention Description

Researchers at Arizona State University have developed an enhanced transformer-less high conversion ratio converter system to meet increasing demands. The enhanced system reduces the number of switches needed to implement a zero voltage transition circuit (ZVT). By allowing a ZVT circuit, the system allows for ripple cancellation on the high voltage side of the converter, in turn allowing for non-pulsating current effectively making filter requirement significantly smaller. Furthermore, the system can be implemented to a variety of ZVT configurations for uni/bi-directional power flow applications. The combination of these factors allows for high ratio conversion with minimal trade-offs and degradation.

Potential Applications

  • Renewable Energy 
  • Electric Transportation
  • Power Supplies for Information Technology

Benefits and Advantages

  • Superior – Modified switch patterns make current smoother when compared to traditional transformer-less high conversion ratio converters
  • Corrective – Multi-module configurations make high-side current non-pulsating
  • Efficient – A Modified zero voltage transition circuit reduces the number of auxiliary switches needed
  • Unrestricted – The conversion of higher power densities allows for multiple power converter applications

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Rajapandian Ayyanar

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