Soft-Switched Step-Up Medium Voltage Power Converters

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dc.contributor.advisorLam, John Chi Wo
dc.contributor.authorAbbasi, Mehdi
dc.date.accessioned2020-05-11T12:34:39Z
dc.date.available2020-05-11T12:34:39Z
dc.date.copyright2019-08
dc.date.issued2020-05-11
dc.date.updated2020-05-11T12:34:39Z
dc.degree.disciplineComputer Science
dc.degree.levelDoctoral
dc.degree.namePhD - Doctor of Philosophy
dc.description.abstractWith a ten-year average annual growth rate of 19 percent, wind energy has been the largest source of new electricity generation for the past decade. Typically, an offshore wind farm has a medium voltage ac (MVac) grid that collects power from individual wind turbines. Since the output voltage of a wind turbine is too low (i.e., typically 400 690 V) to be connected to the MVac grid (i.e., 20 40 kV), a heavy line-frequency transformer is used to step up the individual turbines output voltage to the MV level. To eliminate the need for bulky MVac transformers, researchers are gravitating towards the idea of replacing the MVac grid with a medium voltage dc (MVdc) grid, so that MV step-up transformers are replaced by MV step-up power electronic converters that operate at the medium frequency range with much lower size and weight. This dissertation proposes a class of modular step-up transformerless MV SiC-based power converters with soft-switching capability for wind energy conversion systems with MVdc grid. This dissertation consists of two parts: the first part focuses on the development of two novel groups of step-up isolated dc-dc MV converters that utilize various step-up resonant circuits and soft-switched high voltage gain rectifier modules. An integrated magnetic design approach is also presented to combine several magnetic components together in the modular high voltage gain rectifiers. The second part of this dissertation focuses on the development of several three-phase ac-dc step-up converters with integrated active power factor correction. In particular, a bridgeless input ac-dc rectifier is also proposed to combine with the devised step-up transformerless dc-dc converters (presented in the first part) to form the three-phase soft-switched ac-dc step-up voltage conversion unit. In each of the presented modular step-up converter configurations, variable frequency control is used to regulate the output dc voltage of each converter module. The operating principles and characteristics of each presented converter are provided in detail. The feasibility and performance of all the power converter concepts presented in this dissertation are verified through simulation results on megawatts (MW) design examples, as well as experimental results on SiC-based laboratory-scale proof-of-concept prototypes.
dc.identifier.urihttps://hdl.handle.net/10315/37339
dc.languageen
dc.rightsAuthor owns copyright, except where explicitly noted. Please contact the author directly with licensing requests.
dc.subjectSustainability
dc.subject.keywordsSoft-switched
dc.subject.keywordsStep up
dc.subject.keywordsMedium voltage
dc.subject.keywordsPower converter
dc.subject.keywordsMedium voltage dc (MVdc) grid
dc.subject.keywordsSilicon Carbide (SiC)
dc.subject.keywordsWideband-Gap (WBG) device
dc.subject.keywordsHigh voltage gain
dc.subject.keywordsWind energy systems
dc.subject.keywordsRenewable energy
dc.subject.keywordsPower electronics
dc.subject.keywordsHigh power
dc.subject.keywordsac-dc
dc.subject.keywordsdc-dc
dc.subject.keywordsCoupled magnetics
dc.subject.keywordsHigh-gain rectifier
dc.subject.keywordsBridgeless
dc.subject.keywordsPower factor correction (PFC)
dc.subject.keywordsBoost
dc.titleSoft-Switched Step-Up Medium Voltage Power Converters
dc.typeElectronic Thesis or Dissertation

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