PhD defence by Alex Buus Nielsen
20.09.2021 kl. 14.00 - 17.00
Alex Buus Nielsen, AAU Energy, will defend the thesis "Topology Optimization for High Efficiency Silicon Carbide Based Ground Power Unit"
Topology Optimization for High Efficiency Silicon Carbide Based Ground Power Unit
Alex Buus Nielsen
Professor Frede Blaabjerg
Associate Professor Pooya Davari, Bo Vork Nielsen (ITW GSE), Søren Dahl (ITW GSE)
Associate Professor Pooya Davari
Associate Professor Daniel-Ioan Stroe, Aalborg University, Denmark (Chairman)
Professor Yan-Fei Liu, Dept. of Electrical and Computer Engineering Queens University, Canada
Uffe Borup, Everfuel, Denmark
The modern society has been constantly developing towards a higher integration of electronic equipment and components. This is seen not only in homeappliances e.g. computers, smart phones, lighting, and electrical vehicles,but also in a variety of industrial applications e.g. motor drives and tran-sitioning from hydraulic to electronic systems. The primary driver for thisdevelopment is the advancement in power semiconductors technology thatallow highly efficient, reliable, cheap, and compact power electronic converters. The latest power semiconductor advancement is the production of market available Wide Band Gap (WBG) devices, especially Silicon Carbide (SiC)devices. These devices exhibit far superior performance compared to the current generation silicon based devices. The superior performance allows for a potential even further increase in efficiency and power density, due to the highly reduced loss characteristics. A power electronics application area that is based on silicon devices is the Ground Power Unit (GPU) application. A GPU converts electrical power from a power source, typically the electrical grid, to aircrafts landed in the airports. By using a GPU to supply electrical power to the aircraft, the aircrafts jet engines can be idled or shut off which improves safety, reduces pollution,and reduces noise in the vicinity of the aircraft. The main operation of the GPU is to ensure a high quality and robust output voltage, such that the aircraft can operate sufficiently before take off. Because of the silicon based GPU, it has reached a technological optimization limit, where efficiency and power density improvement potentials are minor andwould be expensive. Therefore, the technological limits of the GPU are addressed by investigating the potential of a SiC integration. The main optimization potential of components in the GPU was identified as the passive components. With a potential high frequency operation of SiC devices, it could be possible to increase the power density of the GPU. To exploit the potential benefits of SiC devices a power electronics topology analysis has been conducted. The analysis both includes a system level and converter level comparison. The proposed topologies were compared based on semiconductor efficiency, circuit and control complexity, passive filter size, electrical performance, and semiconductor cost. The result showed that a SiC based solution could not only improve efficiency and power density by using a high frequency isolation power electronics converter, but simultaneously make use of simple and reliable converter topologies. Furthermore,a parallel modular GPU system has been proposed due to the benefits of cheaper and more efficient SiC converter modules, with an introduced redundancy that allows for easier maintenance and reduced production time. Finally some of the selected SiC topologies have been designed and modelled using a multi-objective optimization process. The process proposed magnetics, semiconductor, heat sink, capacitor, and auxiliary component models to investigate the trade-off between efficiency and power density with an elevated switching frequency. Similarly,using experimentally validated models, the power density of an entire SiC GPU inverter has been shown to potentially by increased by a factor of two compared to a Si IGBT inverter, with a simultaneous higher efficiency.
THE DEFENCE will be IN ENGLISH - all are welcome.