| 摘要 |
PURPOSE:To enable stable operation to be performed without relation to load factor, by controlling differential quantity to be reduced along with increased load in case of correcting frequency with the feedback of the differential quantity of electricity quantity to frequency control system. CONSTITUTION:The output current of an inverter 30 is detected by a current transformer 51. The output of the current transformer 51 is rectified by a rectifier 52. Also, a differential circuit 53 and a gain adjustment circuit 54 for adjusting differential quantity corresponding with load factor, are added. When a motor 20 is placed in an unstable state and the primary current of the motor 20 is increased, then the polarity for increasing the output frequency of the inverter 30 momentarily is corrected. In this manner, in case that the motor 20 is put in a hunting state and in a regenerative mode sphere, namely in case that the frequency of a rotor is more heightened than the output frequency of the inverter 30, the apparatus could be driven with a given slip, and an unstable state can be suppressed. |
