Patent ID: 7944163

Claim:
A sensorless controlling apparatus for controlling a brushless motor including a rotor including a permanent magnet and a stator including stator coils of a plurality of phases for generating a rotating magnetic field to rotate the rotor based on a vector control by calculating an angle of the rotor using a d-axis current, the sensorless controlling apparatus comprising: a speed calculator that calculates speed of the rotor; an angle controller that calculates a correction angle based on a current value of the d-axis current; and an angle calculator that calculates an angle of the rotor at a predetermined time interval by using the correction angle calculated by the angle controller, the rotor speed calculated by the speed calculator, the predetermined time interval, and the rotor angle which has been calculated by the angle calculator at a predetermined time, wherein the angle controller calculates the correction angle (Δθ) based on the current value of the d-axis current by computing the following expression: Δθ= C P ×E+C I ×F where E represents deviation between the current value of the d-axis current and a predetermined command value, C P represents a first constant, F represents an accumulated value of the deviation, and C I represents a second constant.