| 摘要 |
PROBLEM TO BE SOLVED: To provide a process for controlling a driving device of a carrying device switchable between loading operation and no-load operation. SOLUTION: Line voltage having an almost constant line frequency is supplied to a driving motor 26 in a loading operation state, and output voltage of a variable frequency converter 42 is supplied to the driving motor 26 in a no-load operation state. Before switching to the loading operation from the no-load operation or this inverse switching, a variable output frequency of the variable frequency converter 42 is substantially matched with the line frequency by a PLL device 30, and these phases are matched with each other. An operation state is switched immediately after attaining such phase matching. |
