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Title: Power converters for photovoltaic energy generation
Author: Schofield, Daniel M. K.
ISNI:       0000 0004 5346 3017
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2014
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Global demand for renewable energy has provided impetus for increased research into photovoltaic (PV) technology. Photovoltaic modules have intrinsically low efficiency and therefore, to maximise generated electricity, advances must be made in the efficient extraction of energy to maintain viability of their use. In this thesis, efficiency is maximised using novel power electronics. To facilitate advanced design, novel methods for generating accurate models of PV generators are presented. Conventional methods rely on the characterisation of PVs under continuous illumination. These methods cause heating of the module which can degrade the performance below that which would be seen during normal operation. To counter this problem, the use of flashed illumination is presented as a method for unobtrusively generating a PV electrical characteristic which can be used for accurate model-parameter extraction. To develop optimised-switch mode power converters for PVs, the reasons for suboptimal operation in existing converters is analysed and validated experimentally. Whereas existing research has considered the effect of current perturbation at mains frequency, this thesis extends the analysis to 500 kHz, which represents typical switchmode operation. A typical boost converter cannot meet the requirements for optimal power extraction from the PV module and therefore a novel circuit topology based on a SEPIC converter which can achieve optimal conditions is developed and presented. Since the methods for power transfer optimisation presented in this thesis require that the additional hardware is implemented in order to take full advantage of the PV generator, a method is presented whereby the resulting increased cost is significantly reduced. This reduction is achieved through the adaptation of redundant computer power supplies for PV battery charging applications, a method which can be used to produce a PV battery charger with minimal material or design investment.
Supervisor: Martin, Foster Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available