Direct torque control method for induction motor drives based on modified amplitude and angle decoupled control of stator flux

In this paper, a simple and effective algorithm for direct torque and flux control three phase induction motor drive is proposed. In this method, control technique is based on decouple between amplitude and angle of reference stator flux for determining required stator voltage vector. This proposed method eliminates the estimation of stator flux angle to generate stator voltage vector with constant switching frequency. Within 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 is generated from instantaneous rotor angle and slip angle. The amplitude of the reference stator flux is kept constant at rated value. Simulation results for 3 hp induction motor drive for both the proposed algorithm and conventional techniques are presented and compared. The simulation results show that the proposed strategy has many advantages such as reduced torque ripple, nearly sinusoidal stator current.