POWER CONVERSION DEVICE AND CONTROL METHOD THEREFOR

PROBLEM TO BE SOLVED: To provide a power conversion device of which the loss is reduced by controlling balance of a capacitor voltage without increasing a switching loss.SOLUTION: In the power conversion device, an arm is formed by connecting a plurality of unit converters in series for each phase. Each of the unit converters outputs a pulsed voltage with a DC voltage source and a semiconductor switching element. In the power conversion device, a one-pulse control gate signal is given to the semiconductor switching element of the unit converter. In a phase subjected to control, control means rearranges the order of unit converters to which one-pulse control gate signals are given, based on the order of magnitudes of voltages from the DC voltage sources. In the phase subjected to control in such an order that the number of unit converters which are turned on in one cycle of fundamental waves of output voltages becomes a predetermined maximum number of operation stages, the one-pulse control gate signal is given to a semiconductor switching element of a last unit converter corresponding to the rearranged order in the phase subjected to control.SELECTED DRAWING: Figure 1 【課題】スイッチング損失を増やすことなく、コンデンサ電圧のバランスを制御可能とし、低損失な電力変換装置を提供する。【解決手段】実施形態における電力変換装置は、直流電圧源と半導体スイッチング素子によりパルス状の電圧を出力する単位変換器を、各相において複数直列に接続したアームを形成し、１パルス制御ゲート信号を単位変換器の半導体スイッチング素子に与える電力変換装置であって、制御手段は、制御対象の相において、直流電圧源の電圧の大小の順序に基づいて、１パルス制御ゲート信号を与える単位変換器の順序を並べ替え、制御対象の相において、出力電圧の基本波１周期における単位変換器の動作をオンとした数が所定の最大動作段数となる順序において、制御対象の相において並べ替えられた最も後の順序に対応する単位変換器の半導体スイッチング素子に１パルス制御ゲート信号を与える。【選択図】図１