A three-phase soft-switched isolated AC/DC converter without auxiliary circuit
2008 (English)In: IEEE transactions on industry applications, ISSN 0093-9994, E-ISSN 1939-9367, Vol. 44, no 3, 836-844 p.Article in journal (Refereed) Published
This paper describes an ac/dc converter system consisting of a voltage-source converter (VSC) with purely capacitive snubbers and a two-phase by three-phase cycloconverter, connected via a medium-frequency (MF) transformer. By alternately commutating the two converters, it is possible to achieve beneficial switching conditions for all semiconductor devices. A commutation and modulation algorithm is described, which allows for pulsewidth-modulation control of the output voltage while maintaining soft switching. Low-load operation of the converter is a potential difficulty because the load current may be insufficient for recharging the snubber capacitors of the VSC. However, if the cycloconverter is used to momentarily short circuit the transformer, a quasi-resonant commutation mode of the VSC can be achieved, making a fast and soft commutation of the VSC down to zero load possible, without an auxiliary circuit. Furthermore, the design and operation of a 40-kVA prototype converter system are described. The experimental results from the prototype clearly show the practical feasibility of the studied concept.
Place, publisher, year, edition, pages
2008. Vol. 44, no 3, 836-844 p.
cycloconverter, medium-frequency (MF) transformer, soft switching, voltage-source converter (VSC)
Electrical Engineering, Electronic Engineering, Information Engineering
IdentifiersURN: urn:nbn:se:kth:diva-38100DOI: 10.1109/TIA.2008.921430ISI: 000256404300018ScopusID: 2-s2.0-44849084162OAI: oai:DiVA.org:kth-38100DiVA: diva2:436395
39th Annual Meeting of the IEEE-Industry-Applications-Society Location: Seattle, WA Date: OCT 03-07, 2004 2011-08-232011-08-222011-08-23Bibliographically approved