Design of Direct Torque Control of an Induction Motor in FPGA

Direct torque control or DTC is a very latest ac drive technology which can replace traditional PWM drives of open or closed loop control method. DTC describes the control of torque of a motor directly based on the electromagnetic state of the motor as similar to a dc drive. DTC allows the motor's torque and stator flux to be used as the primary control variables which are obtained directly from the motor by using advanced motor theory. The major problems faced by Direct Torque control of an induction machine are the production of the high torque ripples present in the output of the induction motor. The torque ripple is caused by the use of the three level hysteresis comparator for torque comparison. This ripple can be reduced by using a special controller for torque comparison. By proper selection of the torque controller parameters the torque ripple can be reduced. The objective of the thesis is to model and simulate the direct torque control of the induction motor with this technique using MATLAB simulink package and show its feasibility by comparing it with the available DTC method. The models are developed from the various mathematical equations governing the system.