Power conversion device having multi-level structure

A power conversion device according to one embodiment of the present invention comprises: a plurality of converters comprising at least one upper switch and at least one lower switch, and respectively connected to a plurality of cell strings; and an auxiliary power supply unit for supplying driving power to each of the plurality of converters, wherein the auxiliary power supply unit comprises: a primary-side circuit for receiving the voltage of at least one output terminal from among output terminals of the plurality of cell strings; an insulation type converter for outputting voltage to first secondary-side circuits in accordance with the voltage of the primary-side circuit; and the plurality of first secondary-side circuits for supplying the driving power to each of the upper switch of the plurality of converters by using the voltage output from the insulation type converter, wherein the plurality of converters have a multi-level structure.