High voltage generator for eco-friendly plasma-disinfection of seeds

Abstract

In a world where global warming is a growing issue, new solutions need to be found to reduce the carbon footprint. The same is true for the seed breeding industry, which uses energy inefficient ways of disinfecting seeds using hot water baths. A more eco-friendly solution would be the use of cold plasma treatment. This thesis proposes two designs for high voltage generators to achieve this goal. These include the supercascode switch for high voltage pulsed DC operation and the high voltage transformer driven by a ZVS driver to create high voltage AC. Simulations were performed from which it was verified that the supercascode circuit could switch an input DC voltage of 10 kV at 20 kHz. The ZVS driver-transformer combination was shown to be able to generate up to 10 kV peak with a frequency up to 22 kHz depending on the load. Experiments were conducted with the ZVS driver and transformer which was able to match the simulations. However, the transformer turned out to have a coupling coefficient of 87%, which was not enough to be able to generate plasma, as a coupling of around 95% would be required.