Control Strategies for Mutually Commutated Converter Systems without Cycloconverter Turn-off Capability
2008 (English)In: EEE POWER ELECTRONICS SPECIALISTS CONFERENCE RECORDS, 2008, 1344-1350 p.Conference paper (Refereed)
Mutually commutated converter systems consisting of a voltage source converter and a cycloconverter connected by a medium-frequency transformer allow bidirectional AC/DC conversion as well as voltage transformation and isolation by the transformer. However, such converter systems require an extra power conversion stage compared to conventional converter systems, which may result in low system efficiency despite the soft-switching commutation scheme. In order to reduce the power losses in the cycloconverter, it is desirable to utilize fast thyristors instead of IGBTs. As a consequence, the cycloconverter valves lack turn-off capability because a thyristor can not be turned off by its gate. This paper describes and evaluates the most common control strategies in order to control a thyristor-based cycloconverter in a mutually commutated converter system. The behaviour of the cycloconverter depends strongly on the chosen control strategy when one of the output currents approaches zero, which may inherently affect the harmonic properties of the output voltages and currents. Experimental results from a 20 kVA prototype show that it is possible to successfully operate a mutually commutated converter system without turn-off capability.
Place, publisher, year, edition, pages
2008. 1344-1350 p.
, IEEE power electronics specialists conference records, ISSN 0275-9306
Electric inverters, Electric rectifiers, Electric switchgear, Power electronics, Thyristors, Ac/dc conversion, Control strategies, Converter system, Cyclo converter, Fast thyristors, Harmonic properties, Output currents, Output voltages, Power conversion stage, Power losses, Soft-switching, System efficiencies, Turn-off, Voltage transformation, Voltage-source converter, Control systems
Other Electrical Engineering, Electronic Engineering, Information Engineering
IdentifiersURN: urn:nbn:se:kth:diva-14305DOI: 10.1109/PESC.2008.4592121ISI: 000260398500215ScopusID: 2-s2.0-52349110730ISBN: 978-1-4244-1667-7OAI: oai:DiVA.org:kth-14305DiVA: diva2:332109
39th IEEE Power Electronic Specialists Conference (PESC 08) Rhodes, GREECE, JUN 15-19, 2008
QC 201008022010-08-022010-08-022014-12-16Bibliographically approved