| 摘要 |
PURPOSE:To readily suppress the excess current of an inverter by suppressing the slip and the output voltage only when the load current flows over the prescribed value. CONSTITUTION:When the load current of an inverter 4 increases larger than the set value, this is detected by a current detector 15, and the output signal I of the detector 15 is inputted together with the output omegaS of the amplifier 9 to a frequency correcting circuit 16. The output of the detector 15 is inputted also to a voltage correcting circuit 17, which produces an output when it becomes higher than the current limiting value, this output signal is inputted to a voltage instructing circuit 11, so that the output of the circuit 11 decreases in th value lower than the current limiting value instantaneously at the prescribed rate to the ordinarily operating value. When the current I recovers to the value lower than the current limiting value, the output of the circuit 11 gradually recovers to the ordinary value. |
