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.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:632438 |
| Date | January 2014 |
| Creators | Effah, Francis Boafo |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://eprints.nottingham.ac.uk/14007/ |
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