| 摘要 |
PURPOSE:To sustain operation even upon power supply voltage drop without lowering operational efficiency by obtaining a voltage reference and a frequency reference from a speed reference and producing a correction output based on a compensation value. CONSTITUTION:An AC power supply 1 is fed to a VVVF 100 which produces an AC power having a desired frequency based on a voltage control command fed from a phase control circuit 21 and a frequency control command fed from a frequency control circuit 41 thus driving an AC motor 5. Voltage Vm of the motor 5 is fed back, as a voltage detection signal Vf, through a transformer 43 and compared with a voltage reference V* at a voltage control circuit 23 and a current reference I* is outputted so that the difference becomes zero. Input current to the VVVF 100 is fed back, as a current detection signal If, through a current transformer 12 and a current detecting circuit 14 and compared with the current reference I* at a current control circuit 22. An operational command is then outputted so that the difference becomes zero thus outputting a voltage control command from the phase control circuit 21. |
