Patent ID: 7271562

Claim:
A device for controlling the startup of a motor according to a sensorless control scheme in which estimated position and speed of a rotor is used to control the motor, the device comprising: a voltage injector which generates injection voltages to estimate an initial position of the rotor; a motor drive voltage generator which converts stationary-coordinate-system voltages including the injection voltages to three-phase motor drive voltages and applies the three-phase motor drive voltages to the motor; a current extractor which extracts response current components i α-inj ,i β-inj in respect to the injection voltages from two-phase stationary-coordinate-system currents converted from three-phase currents detected upon rotation of the motor; and a position/speed estimator which extracts response current components related to a rotor position from the response current components i α-inj ,i β-inj in respect to the injection voltages to calculate a rotor position error (e), and estimates the speed and position {tilde over (ω)},{tilde over (θ)} of the rotor from the calculated rotor position error (e).