Leo started as Student intern in PowerTech. today he is the newest member of the verification and Validation team and finalized his master in early 2020.
My Master Thesis deals with the development of a 100 kVA three-phase three-level inverter for use in railway technology, as a component of an Auxiliary Power Supply.
The purpose in this power class is to keep the inverter's losses as low as possible in order to be able to build it compactly and with it economically.
The approach is an analysis and simulation of different three-level topologies as well as the construction of a prototype in order to set up a comparison of simulated and measured electrical parameters.
Hence to literature and simulation, the two topologies neutral-point-clamped (NPC) and T-type-neutral-point-clamped (T-NPC) turned out to be the most suitable. The switching losses of various IGBT modules of the two topologies were measured in a semiconductor test bench. Subsequent the module with the lowest switching losses was selected to be built in the prototype. Farther a DC link and a sine wave filter are necessary in this inverter and were designed to.
The next step was the construction of the prototype and the choice and implementation of a suitable modulation method. The control was realized with a real time target machine, which transmits the 10 kHz signals generated from a sine-triangle comparison to the selected drivers.
After a successful functional test of the prototype the losses and the efficiency of the whole inverter, including DC link and sine wave filter, were measured. The efficiency is 98 %. In comparison to the simulated values the measurements are consistent.
Leo Burgthaler, V&V Engineer
PTC Rail OEM GmbH.