抄録
An inverter-fed squirrel cage rotor three phase induction motor with a speed sensor is used in many industrial applications as actuating motors of variable speed servo-systems. However, speed sensors cause problems in the system, reduce the reliability of the system, and increase the cost of the system. In this paper, many methods which determine the rotating speed of these induction motors by using the motor parameters, the instantaneous values of phase voltages and phase currents sensing are explained. And the point at issue of the each sensorless systems are summarized put in order.
