| 摘要 |
PURPOSE:To improve driving comfortableness when a torque command value is changed over from positive to negative by shutting a power conversion device off for a predetermined period of time at the time when a cage is of light load and on elevating drive, and by shutting it off for the period shorter than the predetermined at the time when it is of heavy load and on descent drive. CONSTITUTION:A microcomputer 1A is composed of a reference speed command signal generating means 11, a total voltage application command means 13, a running direction command signal generating means 14, and of shutting off control means 15. In a power conversion device 3, when a torque designated value T is positive, an induction electric motor 4 is torque-controlled for power running, while, when it is negative, the motor is torque-controlled for braking, so as to rotate the induction motor smoothly. When the torque command value T is change-over from positive to negative, based on the running direction command signal from the running direction command signal generating means 14 as well as on the torque command value T from a calculating means 12, a power conversion device 3 is shutt off for a predetermined period of time by the shutting off control means 15, when a cage is of light load and in elevating drive, while it is shut off for a period of time shorter than the predetermined when the cage is of heavy load and in descent drive. |
