| 摘要 |
PURPOSE:To stably operate an AC motor without stop even if stalling by comparing and controlling a voltage reference signal and a voltage feedback signal of open loop control, a frequency reference signal and the prescribed frequency set value, as well as a current feedback signal and the prescribed current set value. CONSTITUTION:After an AC power source is converted into DC via a converter, it is again converted into AC via an inverter, thereby driving an AC motor. A current detector 6 detects the input current of the converter, and a voltage detector 7 detects the terminal voltage of a motor. The speed reference of a speed setter 8 is inputted to an input control circuit 9', is integrated via a resistor 907, a capacitor 909, and an arithmetic amplifier 910, is converted via an absolute value converter 10 into a voltage reference or frequency reference signal, thereby controlling the converter and the inverter. When the motor is stalled, a switch (S) 913 is closed via a comparator 925, and is held at the value of a frequency level setter 918. When the starting current is reduced to the value of the current level setter 917 by recovery, the S 908 is closed, thereby accelerating the motor. |
