Three-level Z-source hybrid direct AC-AC power converter topology

Effah, Francis Boafo (2014) Three-level Z-source hybrid direct AC-AC power converter topology. PhD thesis, University of Nottingham.

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Voltage source inverter (VSI) is the traditional power converter used to provide variable voltage and frequency from a fixed voltage supply for adjustable speed drive and many other applications. However, the maximum ac output voltage that can be synthesized by a VSI is limited to the available dc-link voltage.

With its unique structure, the Z-source inverter can utilise shoot-through states to boost the output voltage and provides an attractive single-stage dc-ac conversion that is able to buck and boost the voltage. For applications with a variable input voltage, this inverter is a very competitive topology. The same concept can equally be extended to the two-stage matrix converter, where a single Z-source network is inserted in its virtual dc-link. The topology formed is, thus, quite straightforward. Its modulation is, however, non-trivial if advantages like voltage buck-boost flexibility, minimum commutation count, ease of implementation, and sinusoidal input and output quantities are to be attained simultaneously.

This thesis presents two novel space vector modulation methods for controlling a three-level Z-source neutral point clamped VSI to enable the use of a boost function. The second of the two space vector modulation methods is then adopted and applied to a three-level, two-stage matrix converter with a Z-source network inserted in its virtual dc-link to increase the voltage transfer ratio beyond the intrinsic 86.6\% limit. Simulation results are supported by experimental verification from two laboratory prototype converters.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Wheeler, P.W.
Clare, J.C.
Watson, A.J.
Keywords: Z-source, Space vector modulation, Two-stage matrix converter, Voltage source inverter
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: 14007
Depositing User: EP, Services
Date Deposited: 05 Nov 2014 11:45
Last Modified: 13 Sep 2016 23:58

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