Date of Award

August 2015

Degree Type

Thesis

Degree Name

Master of Science

Department

Engineering

First Advisor

Robert M. Cuzner

Committee Members

David C. Yu, Naira Campbell-Kyureghyan

Keywords

Efficiency, LCL Filter, Power Density, PV Inverter, SiC MOSFET

Abstract

The opportunities for both power density and efficiency improvements of photovoltaic (PV) inverter have come with the development of commercially available wide bandgap (WBG) devices such as Gallium Nitride (GaN), and Silicon Carbide (SiC).

In this thesis, how the replacement of Silicon (Si) Insulated Gate Bipolar Transistor (IGBT), with SiC Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) affects the power density and efficiency of a solar inverter implementation is presented. The focus is on achieving a minimum volume of the output filter which meet the current harmonic performance of IEEE standard, while meeting the thermal constraint of the semiconductor device. Efficiency improvements are also characterized through an accurate calculation of device and magnetic component losses—the largest contributors to loss in the system.

MATLAB/Simulnk and PLECS are used to assist in the process. Simulation is used to calculate the differential mode pulsed voltages so that the required attenuation of the filter can be determined and to determine the maximum switching frequency at which the device can operate for a given heatsink design. Thus the power density can be compared. At the same time, by using the same filter but changing out devices, the efficiencies at the same power density can be compared.

According to the results, when both use the maximum junction temperature as the constraint, SiC-based inverter can operate at a much higher switching frequency, which leads to a significant decrease in filter components and resulting a higher power density than Si-based inverter. When operating at the same switching frequency, which means keeping the power density the same, SiC devices leads to an improvement in efficiency.

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