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Amara, Fatima (2024) Control limitations of a cascaded H-bridge converter in solid-state substation applications. PhD thesis, University of Nottingham.

PDF (This thesis is corrected version) (Thesis - as examined) - Repository staff only until 20 July 2026. Subsequently available to Repository staff only - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader Available under Licence Creative Commons Attribution. Download (9MB)

Abstract

A substantial transition is underway in the present era, characterised by a growing adoption of electric vehicles (EVs) and the integration of additional renewable energy sources into the utility grid. This shift is necessary for mitigating greenhouse gas emissions and addressing the increasing energy demand. Power electronics is a key facilitator in this transformation, mainly as the integration of small-scale renewable energy sources and EVs occurs at a low voltage DC level (LV) while the existing grid utility operates on an AC system. Consequently, there is an escalating demand for connecting various components to either low DC or AC voltage. An actual example of this integration is evident in the UNFLEX project, where diverse loads with varying voltage ratings are connected to each port, functioning as a power electronics-based transformer. This study concentrates explicitly on a single port of the UNIFLEX-PM converter linked to a low-voltage grid, where multilevel converters such as cascaded H-bridge converters are chosen.

The integration of a single-phase CHB converter in the UNIFLEX-PM configuration simplifies the setup by eliminating the need for isolation through a DC/DC converter, a feature present in Dual Active Bridge (DAB) and DC/DC converters. In the proposed setup, each DC-link of the CHB is connected to uneven loads, operating consistently at a specific power level. However, to fully use the flexibility of power exchange within this system, the converter can interface with various bidirectional power loads. This results in the establishment of a localised grid that serves as a low-bus voltage connection to the grid. This adjustment facilitates the generation of diverse power levels based on the direction taken through each H-bridge of the CHB converter. Appropriate control measures have been suggested to guarantee the CHB converter operates effectively, which are verified using mathematical modelling, simulation verification and hardware-in-the-loop testing.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Clare, Jon Wheeler, Pat Watson, Alan
Keywords:	Power electronics; Multilevel converters; UNIFLEX-PM converter
Subjects:	T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK7800 Electronics
Faculties/Schools:	UK Campuses > Faculty of Engineering > Department of Electrical and Electronic Engineering
Item ID:	77429
Depositing User:	AMARA, FATIMA
Date Deposited:	18 Jul 2024 04:40
Last Modified:	18 Jul 2024 04:40
URI:	https://eprints.nottingham.ac.uk/id/eprint/77429

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