DocumentCode :
182636
Title :
Switching frequency circulating current analysis in parallel-connected multilevel NPC converters
Author :
Dybko, Maxim ; Brovanov, Sergey
Author_Institution :
Dept. of Electron. & Electr. Eng., Novosibirsk State Tech. Univ., Novosibirsk, Russia
fYear :
2014
fDate :
21-24 Sept. 2014
Firstpage :
1195
Lastpage :
1203
Abstract :
This paper discusses one of the major issues concerning parallel-connected voltage source converters that is the circulating currents. These currents usually flow between the converters and can be caused either unequal power sharing between the converters or nonsymmetrical PWM control. In the second case they are called switching frequency circulating currents. Detailed investigation on these currents is carried out. Analytical expressions to calculate the maximum values of these currents are obtained for the common case. Knowing the maximum value allow one to estimate semiconductor maximum current more precisely and prevent IGBT or MOSFET overcurrent fail. It is shown that number of the parallel converters has a slight influence on the switching frequency circulating currents maximum value. On the other hand the number of the voltage levels, PWM frequency and sharing reactor inductance proportionally affects this value. Simulation for several different cases is given to verify the obtained equations and prove the correctness of the assumptions made. An experimental verification on the two-level case is presented.
Keywords :
MOSFET; PWM power convertors; insulated gate bipolar transistors; overcurrent protection; switching convertors; IGBT overcurrent prevention; MOSFET overcurrent fail prevention; neutral point-clamp; nonsymmetrical PWM control; parallel-connected multilevel NPC converter; parallel-connected voltage source converters; power sharing; reactor inductance; semiconductor maximum current estimation; switching frequency circulating current analysis; Equivalent circuits; Inductors; Motion control; Power conversion; Pulse width modulation; current sharing; multicarrier phase-shifted PWM; parallel connected converters;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Power Electronics and Motion Control Conference and Exposition (PEMC), 2014 16th International
Conference_Location :
Antalya
Type :
conf
DOI :
10.1109/EPEPEMC.2014.6980674
Filename :
6980674
Link To Document :
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