Sensorless direct torque and stator flux control of induction machines using an extended Kalman filter

Describes the development of a sensorless speed, direct torque and stator flux control system for induction machines (IM). An extended Kalman filter (EKF) is used for the stator flux and mechanical state estimation of the IM. The observer was developed based on a non-linear model of the IM that employs a /spl alpha/-/spl beta/ stationary reference frame. The torque and stator flux controllers were designed taking into consideration a model of the machine in the rotating reference frame attached to the stator flux phasor. The electromagnetic torque and stator flux, are controlled by non-linear hysteresis controllers; their output signals are used for generating the control signals of the inverter based on a switching table. The angular speed controller is linear of I + PI type.