| 摘要 |
PURPOSE:To suppress surge current flowing into a diode by switching a switching means quickly when a motor current drops below a predetermined level during power regenerating operation thereby enabling powering operation of motor whereas switching the switching means with a predetermined time lag when the motor current is higher than the predetermined level and the power regenerating operation, is interrupted. CONSTITUTION:Upon detection of switching from advance to back or from back to advance, a regenerative contactor 18 is opened and an auxiliary exciting circuit 8 is conducted for a moment thus initiating chopper operation of a transistor 4. Since the polarity of voltage induced in a motor varies as shown by an arrow, motor current circulates through a flywheel diode 10 or a plugging diode 9, a battery 1, and a regenerative diode 7 and the circulation sustains until stoppage of rotation of the motor. When the rotational speed decreases and a predetermined motor current is not obtained even through the chopper operation, the regenerative contactor 18 is closed quickly thus enabling backward powering operation. According to the drop by lagging the operational timing of the regenerative contactor 18. |
