| 摘要 |
PROBLEM TO BE SOLVED: To allow a continued stable operation without causing an overloading even if the acceleration or deceleration operation of an AC electric motor is performed. SOLUTION: This control device comprises a first induction motor 5 for hoist up and a second induction motor 6 for lateral movement. In this case, when a converter 1 reaches a current limit value, the second induction motor 6 for lateral movement lowers change rates of speed reference values Sp and Ref relative to the second induction motor 6 during the acceleration or deceleration and lowers the values of the speed reference values Sp and Ref during the constant speed operation so that a control device 9 performs a control so as to release a current limitation. Thus, the stop of operation due to overload of a converter 1 can be prevented from occurring.
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