| 摘要 |
A power conversion device is constituted by: a power converter that receives AC power and uses this to drive an AC motor; a control section for controlling an inverter section of the power converter; a voltage detection section that detects the voltage of the AC power source; a current detection section that detects the input current of the AC motor; and a speed detection section that detects the rotational speed of the AC motor. The control section has a vector control section that converts the current detected by the current detection section into a torque current component and an exciting current component orthogonal thereto and respectively independently controls these, and, when an electrical quantity found from the voltage detected by the voltage detection section has dropped below a first prescribed value, reduces the instruction value of the torque current component in a prescribed ratio in response to the lowered electrical quantity and, when the electrical quantity has dropped below a second prescribed value smaller than the first prescribed value, reduces the instruction value of the torque current component to zero.
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