Modular multilevel converter ac motor drives with constant torque form zero to nominal speed
2012 (English)In: 2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012, IEEE , 2012, 739-746 p.Conference paper (Refereed)
Modular multilevel converters (M2Cs) are shown to have a great potential in the area of medium-voltage drives. Low-distortion output quantities, combined with low average switching frequencies for the semiconductor devices create the ideal combination for very high-efficiency drives, both from an electric motor and an inverter point of view. With M2Cs the output voltage has such a low harmonic content that high-power motors can be operated without any derating. However, the large number of devices and the existence of capacitors that have to conduct the fundamental frequency current, requires more complex converter control techniques than its two-level counterpart. Special care needs to be taken under starting and operation with low frequency, where the low-frequency current may cause significant unbalance between the submodule capacitor voltages, disturb the output waveforms, and eventually cause the converter to trip. In this paper, principles for converter operation with high torque in the whole speed range, from standstill to rated speed will be investigated. The converter-control method utilizes estimation of the capacitor voltage variation, based on equations describing steady-state conditions. Experimental results from a down-scaled 12 kVA prototype converter running a loaded motor from zero up to the rated speed are provided in the paper.
Place, publisher, year, edition, pages
IEEE , 2012. 739-746 p.
AC motor drives, Capacitor voltages, Constant torque, Converter controls, Fundamental frequencies, Harmonic contents, High torque, Low-distortion, Low-frequency currents, Medium voltage drives, Modular multilevel converters, Output voltages, Output waveform, Prototype converter, Speed range, Steady-state condition, Submodules
Other Electrical Engineering, Electronic Engineering, Information Engineering
IdentifiersURN: urn:nbn:se:kth:diva-107721DOI: 10.1109/ECCE.2012.6342746ISI: 000312901701001ScopusID: 2-s2.0-84870933124ISBN: 978-146730801-4OAI: oai:DiVA.org:kth-107721DiVA: diva2:577751
4th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2012;Raleigh, NC; 15 September 2012 through 20 September 2012
QC 201301242012-12-172012-12-172013-09-06Bibliographically approved