Motor control apparatus and control method for motor control apparatus

A control method for a motor control apparatus, the motor control apparatus comprising:

• a rotor;
• a current detection unit configured to detect a current flowing through the motor;
• a position estimation unit configured to estimate a position of the rotor based on the current detected by the current detection unit;
• and
• a driving voltage generation unit configured to generate a voltage to be applied to the motor based on the position of the rotor estimated by the position estimation unit,
• the control method comprising:
• a counter electromotive voltage estimation step of estimating, by the position estimation unit, a counter electromotive voltage generated in the motor based on the voltage generated by the driving voltage generation unit and the current detected by the current detection unit;
• and
• an arc tangent calculation step of calculating, by the position estimation unit, an angle of deviation by performing an arc tangent calculation using coordinate data on a two-dimensional plane based on the counter electromotive voltage estimated in the counter electromotive voltage estimation step, wherein
• the arc tangent calculation step includes:
• a fundamental-wave rotation calculation step of repeatedly performing, by the position estimation unit, a rotation calculation of coordinate data on a fundamental wave while decreasing a rotation angle;
• a harmonic rotation calculation step of repeatedly performing, by the position estimation unit, a rotation calculation of coordinate data on at least one or more harmonics while decreasing the rotation angle;
• a rotation direction judgment step of judging, by the position estimation unit, a rotation direction of a subsequent rotation calculation in each of the fundamental-wave rotation calculation step and the harmonic rotation calculation step based on a result of the rotation calculation in the fundamental-wave rotation calculation step and a result of the rotation calculation in the harmonic rotation calculation step;
• and
• a deviation angle calculation step of calculating, by the position estimation unit, a total of rotation angles obtained as a result of the rotation calculation in the fundamental-wave rotation calculation step as an angle of deviation of the fundamental wave.