| 摘要 |
PURPOSE:To enable to operate a stable AC machine by controlling in weak- field even if the frequency of an inverter becomes high and controlling the integration while comparing the DC current reference with the mean current of a load even if an AC current reference value is reduced. CONSTITUTION:A rectifier 23 converts load currents iu, iv, iw, into direct currents. An amplifier 22 compares and amplifies the DC current reference with the mean value of the current as the output of the rectifier 23, and proportionally integrates the error between the reference and the mean value. On the other hand, a level detector 24 discriminates at the level the output of a tachometer generator 7, thereby operating a switch 25, and applies the output of the amplifier 22 to an addition amplifier 26 which inputs a DC current reference when the frequency of an induction motor becomes high. In this structure, the DC current reference as the output of a function generator 10 is corrected by the amplifier 26 in response to the frequency of the motor, is converted into the mean current reference, and is inputted to D/A converters 13-15. |
