Patent ID: 8345455

Claim:
A control device of a high voltage inverter, the control device comprising: a phase shift transformer configured to shift phases (R, S, T) of received 3-phase voltage in order to generate a plurality of 3-phase voltages each having a different phase; an inverter configured to switch the generated plurality of 3-phase voltages in order to generate voltages each having a different phase and to output a 3-phase high voltage to a load by combining the generated voltages of each phase, the generated plurality of 3-phase voltages switched by a plurality of U phase unit cells, a plurality of V phase unit cells and a plurality of W phase unit cells; a plurality of current transformers (CTs) configured to detect a current of each phase output to the load by the inverter; and a master controller configured to: determine a current level output to the load by the inverter using an output signal of the plurality of CTs in order to control a switching operation of the inverter; determine whether first output terminals of each of the plurality of U phase unit cells, each of the plurality of V phase unit cells and each of the plurality of W phase unit cells are set UP at a preset neutral point; perform a communication with a cell controller disposed at each of the plurality of U phase unit cells, each of the plurality of V phase unit cells and each of the plurality of W phase unit cells; operate the inverter by allowing each cell controller to be set up with a same neutral point as the preset neutral point; determine a polarity of a current supplied to a load and a polarity of current output by each of the plurality of U phase unit cells, each of the plurality of V phase unit cells and each of the plurality of W phase unit cells if a trip is generated while the inverter is operated, and change the neutral point set up in the master controller and each cell controller in order to operate the inverter if the polarity of the current supplied to the load is different from the polarity of the current output by each of the plurality of U phase unit cells, each of the plurality of V phase unit cells and each of the plurality of W phase unit cells.