| 摘要 |
PURPOSE:To suppress an influence to be affected to the frequency control of the noise of the signal line of a rotating speed detector by performing the frequency control by a rotating speed detection signal in which the maximum and minimum values of the output signal of a rotation detector are removed. CONSTITUTION:Four rotating frequency signals fr1-fr4 calculated as numeric values by a rotating speed detector 11 are input in the order from the larger value to a set calculator 31. The calculator 31 sets the input fr1-fr4 in the order from the larger value to outputs A-D. Further, the outputs B, C are respectively input to minimum and maximum value selectors 21, 22, the output of the selector 21 is used at the time of power drive and the output of the selector 22 is used at the time of regeneration as a reference rotating frequency f4. The frequency f4 and the output fs of a slip frequency pattern generator 14 responsive to the output of a load unit 18 are added or subtracted to obtain an inverter frequency command (f). |
