| 摘要 |
Controlled by switching is which reactor in a reactor group present between a power source and a three-level converter is to be connected to an intermediate point that outputs a midpoint potential. In the switching, the closer to the command value (0) of the midpoint potential the command values (Vr * , Vs * and Vt * ) of input potentials of the converter are, the greater the duty at which corresponding reactors are connected to the intermediate point is for pulse width modulation. Thus, the potential at the intermediate point is set to the command value of the midpoint potential. Additionally, a predetermined range to be compared with the command values (Vr * , Vs * and Vt * ) has a predetermined potential width with respect to an AC waveform (VK) centered around the command value (0) of the midpoint potential. This eliminates the need to detect the polarities of a power supply voltage and a current flowing through the converter for the pulse width modulation. |
