NEW GENERATION THREE-PHASE RECTIFIER Electrical and Electronic Engineering at the University of Canterbury, Christchurch New Zealand EATON POWER QUALITY

NEW GENERATION THREE-PHASE RECTIFIER

By William Phipps A thesis presented for the degree of Doctor of Philosophy In Electrical and Electronic Engineering at the University of Canterbury, Christchurch New Zealand July 2008 ABSTRACT This thesis describes the development of a new gener ation of three-phase rectifier, used to power telecommunications equipment. The traditional topol ogy for such power converters is a single- phase two-stage design, with a boost converter provid ing power factor correction at the input to the first stage and an isolated dc-dc converter making up the second stage. A two-stage design results in the output power being processed twice and this ca scade effect results in an overall reduction in efficiency. A rectifier solution is sought that meet s with all the requirements of the telecommunications industry, while not displaying th e inherent weaknesses associated with a boost-derived topology, and which can be realised in a single-stage design. A number of common three-phase topologies exist that could be realised as telecommunication power supplies, however, they do not completely satisfy all the industry requi rements. A new three-phase rectifier, which is a single-stage buck-derived topology, is proposed. As a consequence of incorporating a buck- derived topology, the three-phase rectifier does not exhibit any issues resulting from startup inrush currents, or high currents due to an output short circ uit condition, as would result in a boost- derived topology. The new proposed rectifier is modu lar in nature, which has the added benefit of redundancy. As a result of the new three-phase rect ifier having a single-stage topology, it is expected that the overall efficiency would able to re ach close to 95%. This is due to the traditional two-stage designs having efficiencies around the 90% mark, and therefore by removing a stage, out of the power conversion process the overall losses w ould also be halved, resulting in the 5% gain in efficiency. The rectifier system requires only one controller as a result of being a single-stage design, thus also reducing the overall system cost. ESTA TESIS FUE FINANCIADA POR LA EATON POWER QUALITY LTD. The initial motivation in developing a new generation of rectifier topology was to see if it would be possible to have a topology that would yield a significant increase in efficiency over the traditional two-stage designs. It was identified that in order to achieve a cost reduction in the rectifier system, an increase the overall efficiency was needed. This would in turn give Eaton Power Quality Ltd. an advantage in the market place.
DOWNLOAD
http://www.mediafire.com/download/i93yka6s7d3cqxm/NEWRETIFICADORTRIFASICO.pdf