This embodiment includes a first circuit and a second circuit connected in parallel to each other, wherein the first circuit includes a first switch and a sub-module capacitor connected in series, and the second circuit includes a second switch. An apparatus for testing a level converter sub-module, comprising: an inverter for receiving a current of a DC power supply and generating an AC current; an inductor connected in series with the output of the inverter and the sub-module through which an inductor current flows; an auxiliary capacitor connected in series to the output of the inverter, the sub-module, and the inductor; an auxiliary power supply unit for providing auxiliary power output to both ends of the auxiliary capacitor so that the voltage of the auxiliary capacitor is kept constant; and a control unit controlling the circuit connection of the DC power supply by controlling the inverter, and controlling the circuit connection of the sub-module capacitor by controlling the first switch and the second switch. do.
展开▼
