Optimal Selection of the Average Capacitor Voltage for Variable-Speed Drives With Modular Multilevel Converters
2015 (English)In: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 30, no 1, 227-234 p.Article in journal (Refereed) Published
Variable-speed drives have reduced voltage requirementswhen operating below the base speed. In a modularmultilevel-converter-based (M2C-based) motor drive it is thenpossible to operate with reduced voltage in the submodulecapacitors, than at the base speed. In this sense, a greatercapacitor-voltage ripple can be accommodated, without exceedingthe maximum peak-capacitor voltage. This paper presents ananalytical investigation for the optimal selection of the averagecapacitor voltage for M2Cs, when the motor is operating withrated torque, below the base speed. This method does not requireany power exchange between the converter arms, so it keepsthe conduction losses at the minimum level. Additionally, themethod decreases the switching losses, due to the decreasedcapacitor-voltage level. The overall ratings of the converterremain the same as in the base-speed operation. It is shownthat this method can be applied at a speed range betweenthe base speed and down to approximately one third of it,i.e, an operating range that covers the requirements for typicalpump- and fan-type applications. The results obtained from theanalytical investigation are experimentally verified on a downscaledlaboratory prototype M2C.
Place, publisher, year, edition, pages
2015. Vol. 30, no 1, 227-234 p.
Capacitor-voltage control, medium-power variable-speed drives, modular multilevel converters, optimization.
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject Electrical Engineering
IdentifiersURN: urn:nbn:se:kth:diva-156198DOI: 10.1109/TPEL.2014.2316273ISI: 000341624200019ScopusID: 2-s2.0-84906809639OAI: oai:DiVA.org:kth-156198DiVA: diva2:765741
QC 201412012014-11-242014-11-242015-06-26Bibliographically approved