Patent ID: 8072165
Filing Date: 2011-12-06
Classification: H02P

Abstract:
1. An apparatus for estimating rotor position for brushless motors which includes a brushless motor having a stator with coils wound thereon and a rotor rotatably supported relative to the stator and estimates the stop position of the rotor, the estimating apparatus comprising: a current detecting means for directly or indirectly detecting wiring current which is current passed through the coils; a voltage supplying means capable of supplying voltage to the coils so that magnetic flux is produced in each of a plurality of directions perpendicular to the direction of rotation of the rotor; a power source voltage detecting means for detecting the voltage of a power source used for the voltage supply; a voltage supply controlling means which controls the voltage supplying means so that magnetic flux is produced in sequence in predetermined directions among the directions and, when a predetermined voltage supply time has passed, terminates the supply of voltage by the voltage supplying means; a current correcting means which corrects wiring current detected at the current detecting means based on power source voltage detected at the power source voltage detecting means and preset reference voltage in each direction in which magnetic flux is produced under control of the voltage supply controlling means; and a rotor position estimating means which compares wiring currents corrected by the current correcting means to identify a direction in which the peak amplitude value of wiring current is maximized and estimates the stop position of the rotor based on the identified direction.