OPERATION CONTROLLER FOR MOTOR

PROBLEM TO BE SOLVED: To provide an operation controller for a motor by which stable speed control is executed, even at a low-speed rotation close to zero. SOLUTION: When a power-converting part 3 converts a DC to an AC and supplies it to the motor 4, a current-detecting means 8 detects a current flowing in a winding of the motor, on the basis of the voltage generated in resistors 6, which are respectively connected to a current input route to the power converting part; and a rotor speed estimation calculating means 9 estimates the rotational frequency of the motor, on the basis of a torque component and the excitation component of a voltage command value supplied to the motor, and the current detected by the current detecting means. When a waveform-generating means 15 generates a drive waveform signal, which is for driving the power converting part on the basis of the torque component and the excitation component of the voltage command value, and the rotational frequency of the motor estimated by the rotor speed estimation calculating means, an excitation correction control means 16 increases the excitation component of the voltage command value, in such a range that the rotational frequency of the motor estimated with the rotor speed estimation calculating means 9 becomes lower than the prescribed value. COPYRIGHT: (C)2005,JPO&NCIPI