BALANCING OF SUBMODUL VOLTAGES IN THE ARMS OF A MODULAR MULTILEVEL CONVERTER OPERATING AT A HIGH MODULATION INDEX

摘要

The invention relates to a method for operating a converter arrangement (1) with a modular multi-stage converter (2) which comprises at least one converter arm (5-10) with a series connection of two-pole switching modules (SM1, SM2), each of the switching modules having several semiconductor switches and an energy store wherein at least some of the switching modules are switching modules of a first type (SM1) and at least some more of the switching modules are switching modules of a second type (SM2), in which an arm voltage is generated at the at least one converter arm, which causes an arm current through the converter arm. The method is characterized in that a converter circuit current is generated by the converter to generate an arm current zero crossing. The invention also relates to a converter arrangement by means of which the method according to the invention can be carried out.