Direct load angle control of three phase induction motor drives

In this paper, a direct load angle (DLA) control method for three phase induction motor drives is proposed. It is based on control of incremental change in load angle. This method offers constant switching frequency at different operating conditions. The torque control is achieved without losing the benefits of direct torque control (DTC) by reference stator flux angle, which is sum of load angle and rotor flux angle. Proposed DLA control method is applied to two level and three level voltage source inverter fed induction motors and results are presented. From the simulation results it is found that the proposed DLA control scheme impressively reduced the torque and flux ripples when compared with conventional DTC.