During the last year of my studies at NTUA, I pursued my Diploma thesis at the Laboratory of Electric Machines and Power Electronics, supervised by Prof. Antonios Antonopoulos. My work focused on the Modular High Frequency Converter (MHFC), a topology that is well suited for high-performance electric-drive applications such as future electric-aircraft propulsion. Several key-characteristics of the converter are its modular nature, the existence of a DC/DC conversion stage and the extremely small input inductance, enabled by the use phase-shifted switch-control signals.

A 1 kW, 3-submodule MHF converter prototype with a switching frequency of 97.66 kHz was designed and implemented. The power semiconductor switches and the DC-link capacitor devices were selected after evaluating several available components. The switching dynamics as well as the effect of PS-PWM on the inductor current ripple were experimentally investigated. The converter was used to drive an induction motor in a 3-phase AC-stage configuration. It was demonstrated that stable operation can be achieved even without closed-loop balancing control.

The full text of the thesis (in Greek) is available on the repository of ECE, NTUA. A synopsis in the form of presentation slides can be found below: