Patent ID: 7482777
Filing Date: 2009-01-27
Classification: H02P

Abstract:
1. A motor control device comprising a current detecting portion for detecting phase current that flows in an armature winding of a stator of a three-phase motor based on current that flows between an inverter for driving the motor and a DC power supply, the motor control device performing a position sensorless vector control for the motor based on a control current that is obtained by a three-phase to two-phase conversion of the phase current based on an estimated rotor position of the motor, the motor control device further comprising: a superposing portion for superposing a superposed voltage having a predetermined frequency on a drive voltage for driving the motor; and an estimating portion for deriving the estimated rotor position based on a superposed current that is extracted from the control current and flows in the motor in accordance with the superposed voltage, wherein a voltage vector locus of the superposed voltage from the superposing portion presents an ellipse.