| 摘要 |
PURPOSE:To suppress the rush current of load current, by controlling the load current at the time point of a peak load to be constant. CONSTITUTION:In case that a press machine 14 is driven and press working is performed, and when the pressure of the press machine 14 is worked, then a rotational speed is reduced. Along with this reduction, the load current IL of an induction motor 46 is increased. The increment of the load current IL is detected by a current detector 16, and when the detected value exceeds a previously set rating value, then by a current regulator 48, the frequency of control signal fed to a power converter 44 is lowered. As a result, the power converter 44 is pulse-width-modulation-controlled, and the load current I1 is limited to a constant value. |
