Speed sensorless voltage compensation vector control for induction motors by adaptive rotor flux estimation and phase-locked loop

This paper investigates a speed sensorless voltage compensation vector control (VCVC) for induction motors (IMs) to achieve speed tracking. For acquiring the rotor flux length and its rotation angle with respect to stationary reference, an adaptive rotor flux estimator (ARFE) is first designed wherein measurable stator voltage and current information are used. Afterwards, a type-3 phase-locked loop (PLL) is employed to extract the synchronous electrical speed from the available stator phase voltages. Since the PLL introduces distinct estimation errors, an offset is used to adjust the speed estimation. By aid of the ARFE and PLL, a speed sensorless VCVC is finally proposed. The proposed method guarantees the desired rotor speed tracking with a pre-scheduled convergence rate. Finally, the proposed method is validated by an numerical simulation and a real-world application.