Speed estimation of induction motor by using observer and PWM carrier frequency components

Induction motor drives without speed sensors have been developed in these years. This paper presents a speed estimation of induction motors by using an observer and PWM carrier frequency components. In this method, three phase triangular carrier waves are used at zero and low frequency and an observer is used at other frequency. The proposed method is not affected from the stator resistance error or low induced voltage at zero and low frequency. So, speed estimation for a wide range of frequency is available. The validity of the proposed method is verified by experiments.