| 摘要 |
PURPOSE:To accurately control a speed by driving a hoisting motor of a thrust brake by the output voltage of an inverter which outputs a driving voltage having a frequency responsive to a difference between a speed command value and a speed detected value, and controlling the speed of a main motor. CONSTITUTION:A voltage VD of a frequency responsive to a difference between a speed command value Vp and a speed detected value Vd is outputted from an inverter 46, and a hoisting motor 28 of a thrust motor is driven. That is, when the speed of the motor 16 is faster than the value Vp, the output frequency of the inverter 46 is reduced, the motor 28 is decelerated, and hence the hoisting force is reduced to increase a brake torque, thereby decelerating a main motor 16. On the contrary, when the speed of the motor 16 is slower than the value Vp, the output frequency of the inverter 46 is increased, the motor 28 is accelerated to increase the hoisting force, thereby reducing the brake torque to accelerate the motor 16. Thus, the set speed can be accurately controlled. |
