Patent ID: 8164287

Claim:
A motor drive control apparatus configured to control operation of an AC motor, the motor drive control apparatus comprising: an inverter arranged to use a voltage supplied from a DC power source and drive the AC motor; a rotational position detector arranged to detect a rotational position of a rotor in the AC motor; an error acquisition module configured to obtain a detection error of the rotational position detector; a limit phase setting module configured to, in application of a square wave voltage from the inverter to the AC motor to make the AC motor output a torque equivalent to a target torque, correct a phase of the square wave voltage for maximizing an absolute value of an output torque of the AC motor with the detection error of the rotational position detector obtained by the error acquisition module and to set the corrected phases to limit phases of the square wave voltage; a target voltage phase setting module configured to set a target voltage phase of the square wave voltage within a phase range defined by the limit phases set by the limit phase setting module, so as to reduce a torque difference between the target torque and the output torque of the AC motor; and an inverter controller configured to control the inverter based on the rotational position of the rotor in the AC motor detected by the rotational position detector and the target voltage phase set by the target voltage phase setting module.