Patent ID: 8174217

Claim:
A speed-sensorless control apparatus for an induction motor, comprising: a rotating-speed locked loop receiving a rotor angular speed command and an estimated electromagnetic torque of the induction motor, and emulating a speed control loop of the induction motor for producing an emulated torque current and an emulated rotor angular speed; and a feed-forward magnetizing-axis angular position emulator receiving the emulated torque current and the emulated rotor angular speed for producing a feed-forward estimated magnetizing-axis angular position, wherein according to the feed-forward estimated magnetizing-axis angular position, a first voltage controlling the induction motor is transformed from a synchronous reference coordinate system of the induction motor to a static reference coordinate system of the induction motor, and a two-phase current detected from the induction motor is transformed from the static reference coordinate system to the synchronous reference coordinate system.