| 摘要 |
PROBLEM TO BE SOLVED: To detect a slip state even when a plurality of AC motors are driven, to transfer to constant-speed operation when a slip reaches a fixed value or more and to conduct re-acceleration when the slip reaches the fixed or less. SOLUTION: Switches 22 and current detectors 24 are installed between AC motors 611, 612,...61n and an inverter device 1. Average current vector signals prepared by outputs from the current detectors 24 and current vector signals at every AC motor are compared. The frequency of the inverter device 1 is transferred from acceleration to constant speed while voltage is increased by a fixed quantity, and the acceleration torque of the AC motor 61 of interest is increased when abnormality is decided, when current vectors reach a fixed value or more in comparison with average current vectors regarding magnitude and phase by the comparison, and re-acceleration is started when abnormality is eliminated. |
