| 摘要 |
PURPOSE:To drive the motor in stability in a low current state by a method wherein when the AC motor is driven using a plurality of power converters, phases of the output currents are controlled in order to prevent the output currents of the individual power converters from decreasing under a prescribed current. CONSTITUTION:A control circuit 20 feeds a current value i11 and a current phase angle theta1 to a rectifier and an inverter circuit on one side, and a current value i12 and a current phase angle theta2 to the rectifier and the inverter circuit on the other side with a field current component i1d of an induction motor and a torque current component i1q as inputs. In a divider 23, an output of an operation circuit 21 calculating an absolute value of a primary current is divided by the lowest current set-up by a current setter 24, and if the output obtained as described above is more than 1, a switch 26 is closed by a control signal of a discriminating circuit 25. If the above- mentioned output is under 1, the phase angle which is adjusted with a phase correction calculated in an operation circuit 27 and said lowest current value are made to output through a switch 30. |
