Sensorless control of induction motors with on-line rotor time constant adaptation

This paper presents a novel vector control scheme for the sensorless control of induction motors with on-line rotor time constant adaptation. The motor speed can be estimated using only phase currents and DC-link voltage. An adaptive voltage compensation scheme is proposed to compensate nonlinearities resulted by the PWM inverter and to eliminate time delay of the sensing filters. The proposed online rotor time constant adaptation scheme is developed from a power transfer parameter identification algorithm to reduce sensitivity due to parameter mismatch and environment change. The proposed auto-tuning sensorless control scheme has been realized using a single-chip DSP controller (TMS320C14) from Texas Instruments. Experimental results reveals the proposed auto-tuning sensorless control scheme can achieve fast transient response and maintain a wide speed control range.