| 摘要 |
An inverter control apparatus includes an instruction calculator (6) which receives a speed instruction (fn*) and a particular component of a current of a motor to obtain an output frequency instruction (f1*) and output voltage instructions (Vd*, Vq*) of an inverter (4) and a current estimator (11) to estimate, according to a reference phase obtained by integrating a current detection value (iu) of one phase of an ac motor (1) and an output frequency instruction (f1*) thereof, currents (Id, Iq) of other phases of the ac motor. The current estimator (11) includes a uvw/dq converter (16) which converts a fixed coordinate system into a rotating coordinate system, a dq/uvw converter (18) which is connected to the uvw/dq converter (16) and which converts the rotating coordinate system into the fixed coordinate system, and a closed loop to input an output from the dq/uvw converter (16) to the uvw/dq converter (18). This system can therefore estimate currents of other phases according to the motor current of one phase. <IMAGE> |
