document: Use of extra degrees of freedom in multilevel drives Multilevel converters with series connection of semiconductors allow power electronics to reach medium voltages -LRB- 1-10 kV -RRB- with relatively standard components . The increase of the number of semiconductors provides extra degrees of freedom , which can be used to improve different characteristics . This paper is focused on variable-speed drives and it is shown that with the proposed multilevel direct torque control strategy -LRB- DiCoIF -RRB- the tradeoff between the performances of the drive -LRB- harmonic distortions , torque dynamics , voltage step gradients , etc. -RRB- and the switching frequency of the semiconductors is improved . Then , a slightly modified strategy reducing common-mode voltage and bearing currents is presented
doc_bio_tags: O O O B I I O B I O O O B I O B O B I O O B I O O O O O O O O O O O O O O O B O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O B I I I I O O O O O O O O O O O O B I O B I O B I I O O O O O B I O O B O O O O O O O O O O O O O B I O O
extractive_keyphrases: degrees of freedom series connection semiconductors power electronics medium voltages multilevel direct torque control strategy harmonic distortions torque dynamics voltage step gradients switching frequency bearing currents multilevel drives
abstractive_keyphrases: variable-speed drives common-mode voltage reduction delay estimation industrial power systems insulated gate bipolar transistors state estimation fixed-frequency dynamic control 1 to 10 kv