Simple observer for induction motor speed sensorless control

The paper presents a speed sensorless field oriented control drive of the induction motor operating within a wide speed range. Easy and convenient for industrial application, a new structure of both flux and speed estimation is proposed. The flux computation block uses simple relations mainly based on stator circuit equations with easily accessible feedback signals to improve the operation range and system robustness. The observer is appropriate for a wide speed range, including the lower region of the stator frequency and very high speed as well. The proposed approach ensures the possibility of the sensorless drive operation without an accurate modeling of the inverter nonlinearities or on-line parameter adaptation, thus offering a simple and robust solution. The effectiveness of the system with the new observer structure has been verified by experiments.