| 摘要 |
PURPOSE:To reduce the rotating ripple and unstable phenomenon of an AC motor controlled by an inverter by controlling the carrier frequency of the inverter so as not to decrease upon rising of the operating frequency. CONSTITUTION:A speed command voltage is multiplied by multipliers 66-68 by the outputs of sinusoidal wave generators 62-64, and in case of the normal motor drive, it is controlled to have V/F=constant. After the signals of comparators 69-71 for comparing the sinusoidal waves with a triangular wave and the reverse signals are applied to delay circuits 72-77 for taking a timing to prevent the short circuit of upper and lower arms, transistors 3, 6, 4, 7, 5, 8 are driven. Reference sinusoidal waves having different phases of 120 deg. are generated from sinusoidal wave generators 62-64. |
