| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a power conversion system such that, although a cascade multilevel converter has a DC capacitor for each unit cell and a cascade multilevel conversion system needs to suppress harmonics by shifting carriers at equal intervals with respect to each of the unit cells and also to make DC capacitor voltages of the respective unit cells uniform, there is a problem that the DC capacitor voltages become unbalanced when voltage command values of each of the unit cells are equalized and the carriers of the respective unit cells are shifted, and the cascade multilevel conversion system which suppresses the harmonics by shifting the carriers with respect to each unit cell, however, is unlikely to have unbalance of the DC capacitors. <P>SOLUTION: In the cascade multilevel converter, a deviation between amplitude and a shift of each of the unit cells caused by PWM are corrected in a feedforward fashion and unbalance of the DC capacitor voltages is hardly caused. <P>COPYRIGHT: (C)2012,JPO&INPIT |
