ÇOK KATMANLI BASKI DEVRE ÜZERİNDE YÜKSEK AKIMLI MANYETİK DEVRE TASARIMI İLE ÇOK YÜKSEK GÜÇ YOĞUNLUKLU, TEK FAZLI GaN EVİRGEÇ TASARIMI VE GERÇEKLEŞTİRİLMESİ

Abstract

In this thesis, a systematic approach to the design and development of a high power density, natural-convection-cooled, single-phase inverter with a multilayer, high-current PCB magnetics, is presented. The size and efficiency of inverters implemented with the silicon transistor technology have almost reached a certain limit. The use of wide bandgap power semiconductors, such as the silicon carbide (SiC) power MOSFET and the gallium nitride (GaN) enhancement-mode (e-mode) transistor, with a proper circuit layout, not only pushes further the efficiency limits, but also shrinks the inverter size. A systematic approach is proposed here in order to obtain a high power density, and high efficiency single-phase GaN inverter which relies basically upon two new approaches: the derivation of analytical expressions for the inverter losses as a function of the inverter modulation index, for the optimum transistor and highest switching frequency pair selection, and the design of the output filter inductor based on a multilayer, high current PCB magnetics. In the developed 5-kVA single-phase inverter, GaN e-mode transistors are used to minimize the inverter power losses and to decrease the cooling requirement, and size of the system. A quantative comparison between power losses of GaN e-mode transistors and the other candidate transistors, such as silicon and silicon carbide power MOSFET with similar specifications, is performed. Computer simulations are carried out on LTspice ve MATLAB Simulink computer programs in order to observe both the switching characteristics of the GaN transistors and the performance of the whole single-phase inverter under load. The proposed systematic design approach has been verified on the implemented 5-kVA, 50-kHz, naturally-air-cooled (convection) GaN inverter. A power density of 2.7 W/cm3 (44.3 W/inch3), and a full-load efficiency of 98 % is achieved with the designed inverter.