Digital Simulation of Conventional Direct Torque Control of Induction Motor Drive with Reduced Flux and Torque Ripples

The induction motors are known as the workhorses of industry because of its simple construction and robustness. Traditionally, the induction motor has been used in constant and variable speed drive applications that do not cater for fast dynamic processes. Because of recent development of several new control technologies, such as vector control, sensor less control and direct torque control (DTC), the situation is changing rapidly. The Direct Torque Control (DTC) technique has the feature of precise and quick torque response and reduction of the complexity of field oriented control (FOC) algorithms. In DTC, the generation of inverter switching state is made to restrict the stator flux and electromagnetic torque errors with in the respective flux and torque hysteresis bands so as to obtain the fastest torque response and highest efficiency at every instant. In this paper, a detailed mathematical modeling of induction motor is proposed and then a conventional direct torque control method is implemented where the torque and flux of an induction motor can be directly and independently controlled without transformation using MATLAB simulation.