Sensorless SVM-DTC method for induction motor drives based on amplitude and angle decoupled control of stator flux

This paper proposes an algorithm for direct flux and torque controlled sensorless three phase induction motor drive systems. This method is based on control of slip speed and decouple between amplitude and angle of reference stator flux for determining required stator voltage vector. Within the given sampling time, flux as well as torque errors are controlled by stator voltage vector which is evaluated from reference stator flux. The direct torque control is achieved by reference stator flux angle, which generates from instantaneous slip speed angular frequency and stator flux angular frequency. The amplitude of the reference stator flux is kept constant at rated value. This technique gives better performance in sensorless three phase induction motor than conventional technique. Simulation results for 3 hp induction motor drive for both proposed and conventional techniques are presented and compared. From the results it is found that the stator current, flux linkage and torque ripples are decreased with proposed technique.