Analysis, Modelling, Design, and Control of DC-DC Converter for Renewable Power Generation Systems

Global energy demand is rapidly growing and therefore meeting the future energy demand is becoming a major concern worldwide. To meet the energy demand, fossil fuels are still used as the primary energy source. However, these hydrocarbonbased fuels produce greenhouse gases that adversely affect environment and human health. Therefore, alternative renewable energy sources such as solar, wind, hydro, biomass and geothermal are getting very popular. Currently, development of power converters for these renewable energy sources is becoming more and more essential for converting this energy to appropriate voltage levels or feeding it to electrical power distribution networks. This research study is focused on the DC-DC boost converter analysis, design, modelling, and using current control techniques for singlephase uninterruptible power supply (UPS) inverter systems. The major contributions of the presented work can be categorized into two parts: Firstly, a comprehensive analysis of classical and advanced DC-DC converter topologies for renewable power applications. DC-DC power converters have attracted significant attention due to their increased use in a number of applications from aerospace to biomedical devices. The interest in wide bandgap (WBG) power semiconductor devices stems from outstanding features of WBG materials and power device operation at higher temperatures, larger breakdown voltages and sustaining larger switching transients than silicon (Si) devices. As a result, recent progress and development of WBG power devices based converter topologies are well-established for power conversion applications in which classical Si based power devices show limited performance. Currently, WBG devices such as silicon carbide (SiC) and gallium nitride (GaN) are the most promising semiconductor materials that are being considered for new generation of power devices because of their high voltage operation, high current switching capabilities, very low ON resistance, good thermal conductivity, etc. Secondly, a cost effective design of Gallium nitride (GaN)-based high-frequency, high efficiency DC-DC boost converter owing to preferred soft-switching features. The use of new power semiconductor devices such as GaN high electron mobility transistors (GaN HEMTs) are able to minimize switching losses, allowing high switching frequencies (from kHz to MHz) for realizing compact and fully integrated power converters. Finally, PI and PR control parameters are optimally tuned, and experimentally tested for single-phase UPS inverters to obtain very low total harmonic distortion (THD), zero steady-state error, and fast response. This research presents detailed analysis and mathematical models of PI and PR controllers in single-phase UPS inverter applications. In order to realize the importance of PR control features over conventional PI controllers, a PI controller is implemented in the same UPS inverter and mathematically analyzed. The performance of these controllers is analyzed in terms of steady-state is and transient responses and current harmonics level. The experimental result shows that the PR controller achieves zero steady-state error, improved transient response and reduced low-order harmonics distortion of the output current compared to PI controller. The performances of the implemented controllers are simulated and compared using the MATLAB/Simulink modeling environment. The main significance of this work is the design and development of a DC-DC boost converter, and optimization of controller parameters for high power application such as Electric Vehicle (EV) charging, aerospace, renewable power generation, etc.Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 202