| 摘要 |
PROBLEM TO BE SOLVED: To provide a controller for an AC motor for controlling torque accurately in a full range from low rotational speed to high rotational speed in the AC motor. SOLUTION: A controlling method selecting circuit 13 changes a contact of a switching circuit 19 in a way that a PWM signal from a current feed-back circuit 11 is entered in an excitation circuit 12 when a rotational speed Nm of a motor 1 is high, and a PWM signal from an AND gate circuit 14 is entered when the rotational speed Nm is low. In addition, input power in an inverter circuit is made equal to a target value under feed-back control of a power feed-back circuit 10, while a phase current is made equal to a target value under feed-back control of the current feed-back circuit 11. |
