High-Voltage Power Converters for Stratospheric Airship Ion Propulsion

Advancements in ion propulsion technology for stratospheric applications are poised to revolutionize various industries, including aviation, climate monitoring, telecommunications and other stratospheric missions. When using ion thrusters in the atmosphere, a significant challenge presents itself due to the need to operate at lower altitudes where air densities are higher, in contrast to the near-vacuum conditions of space. To accommodate the denser atmospheric environment, modifications and refinements in thruster design are required. The development of compact and efficient high-voltage converters play a crucial role in employing the potential of ion thrusters to enable sustainable, high-performance airship propulsion systems. This thesis aims to design an high-voltage converter suitable for integration into stratospheric airships. A combination of a push-pull front-end converter and a Cockcroft-Walton back-end voltage multiplier with a center-tapped transformer, is presented, designed and tested. This topology allows for the effective transformation of low-voltage input to the higher voltages required for ionization, ensuring electrical insulation. In this thesis, first and foremost, the state-of-the-art of ion thrusters and power electronic converters used for this application is analyzed. A theoretical introduction of the selected converter operating principle is made and, afterwards, simulations are carried out through PLECS (Plexim) and LTspice environments. Finally, the considerations about the selected converter topology are experimentally validated with a scaled-down prototype. All simulation and experimental results are post processed using MATLAB (Mathworks) environment.