| 摘要 |
PROBLEM TO BE SOLVED: To decrease the dispersion of the speeds of a plurality of induction motors by operating the slip frequencies of the induction motors based on the phases of the secondary currents of the induction motors with respect to the primary voltages, adding the slip frequencies to the speed-command values of the induction motors, thereby obtaining the new primary-frequency command value. SOLUTION: The phases θ of the secondary currents with respect to the primary voltages in a plurality of induction motors M1 -MN are estimated and operated based on the output voltage and the current of a power converter 1 by a secondary-current-phase operating means 102. From the estimated and operated phases θ, all slip frequencies fS of the respective induction motors M1 -MN are operated in a slip-frequency operating means 103. The slip frequencies fS and speed command values f** of the respective induction motors M1 -MN are added to each other, and it is adopted as a new frequency command value f*. Thus, the dispersion in the speeds between a plurality of the induction motors M1 -MN can be made small. |
