A novel method to estimate speed for the induction motor at wide range speed

A novel estimation technique of rotor speed of induction motor is proposed. The new estimation method is to estimate directly rotor speed using stator flux and rotor flux. Speed adaptation law in Model Reference Adaptive System (MRAS) or Speed Adaptive Flux System (SAFO) is not employed because the proportional and integral gains in the adaptation law are difficult to determine for wide operation region. In the proposed method, the stator and the rotor flux is estimated based on the dynamic model of the induction motor and the speed of the motor is then calculated using the estimated flux. The speed can be calculated well at very low speed even very close to zero speed.