| 摘要 |
PURPOSE:To eliminate an elctromagnetic contactor for controlling the voltage applied to a motor by switching the output voltage of an inverter to switch the voltage applied to the motor at starting time. CONSTITUTION:The output voltage of an inverter INV and its frequency are controlled to values corresponding to the set voltage VS of a setter 20 by the operations of a voltage instructing circuit 2 and a frequency instructing circuit 1. When an electromagnetic contactor MC is closed at starting time, the analog switch 32 of a correcting circuit 3 is opened, and an integrator 36 is operated. Thus, the output voltage of an amplifier 34 becomes H level after a predetermined time determined by a variable resistor 33 and a capacitor 35, an analog switch 37 is closed to shortcircuit the feedback resistor 29 of the amplifier 27 of the instructing circuit 2. As a result, the gain of the amplifier 27 drops, and a voltage command VCMD drops at the value corresponding thereto. |
