SiC Schottky Diodes and Polyphase Buck Converters

Publication Year:
2007
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Repository URL:
https://corescholar.libraries.wright.edu/etd_all/181
Author(s):
Galigekere, Veda Prakash N.
Tags:
Department of Electrical Engineering; SiC; Schottky; Polyphase Buck; Reverse Recovery; Electrical and Computer Engineering; Engineering; Department of Electrical Engineering; SiC; Schottky; Polyphase Buck; Reverse Recovery
thesis / dissertation description
The turn-on characteristics of a SiC Schottky diode are analyzed theoretically, by simulation, and by experiment. The static characteristics of SiC Schottky diodes and Si junction diodes are analyzed for normal and high temperatures. The effects of diffusion capacitance and junction capacitance on the turn-off transition of SiC Schottky diode have been analyzed theoretically. The turn-off transition of a SiC Schottky barrier diode is analyzed by modeling the metal-semiconductor junction capacitance considering the linear and the non-linear effects. Behavior of the linear and the non-linear metal-semiconductor junction capacitance models are evaluated exper- imentally. The performance of SiC Schottky diodes is compared to the performance of similarly rated Si junction diodes. The effect of diode reverse-recovery current on the primary switch of a PFC boost converter is analyzed by the aid of PSPICE simulations. A 250 W, PFC boost con- verter is designed and simulated. In the 250 W PFC boost converter, the perfor- mance of SiC Schottky diode and similarly rated Si junction diodes are evaluated. The PSPICE simulation models of a SiC Schottky diode and two Si junction diodes are compared and some important parameters are discussed and their effect on the turn-off transition of the diodes are presented. The principle and advantages of polyphase operation of buck converters is ana- lyzed. The design equations for a two-phase buck converter operating in CCM are derived. A two-phase 6 V/120 W (PWM) buck converter is designed and simulated using PSPICE. The design equations are verified by PSPICE simulation results.