High-efficiency voltage source converters with silicon super-junction MOSFETs

Student thesis: Doctoral Thesis

Abstract

High-efficiency power converters have the benefits of minimising energy consumption, reducing costs, and realising high power densities. The silicon super-junction (SJ) MOSFET is an attractive device for high-efficiency applications. However, its highly non-linear output capacitance and the reverse recovery properties of its intrinsic diode must be addressed when used in voltage source converters (VSCs). The research in this thesis aims at addressing these two problems and realising high efficiency. Initially, state-of-art techniques in the literature are reviewed. In order to develop a solution with simple hardware, no major auxiliary magnetic components, and no onerous timing requirements, a dual-mode switching technique is proposed. The technique is demonstrated using a SJ MOSFET based bridge-leg circuit. The hardware performance is then experimentally investigated with different power semiconductor device permutations. The transition conditions between the two switching modes do not have to be tightly set in order to maintain a high efficiency. The dual-mode switching technique is then further investigated with a current transformer (CT) arrangement embedded in the MOSFET's gate driver circuit in order to control the profile of the MOSFET's incoming drain current at turn on. The dual-mode switching technique, with or without a CT scheme, is shown to achieve high efficiency with minimal additional hardware.
Date of Award25 Oct 2021
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorNeville McNeill (Supervisor) & Barry Williams (Supervisor)

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