Publication

Abstract : This work discusses with Direct Torque Control (DTC) of Induction motor using 7 Level NPC Multilevel inverter for reducing the complexity in conventional DTC method. Methods: The limitation of traditional DTC scheme is more distortion in torque profile and the mean torque output never meets the torque demand. To get better performance of the traditional DTC a Space Vector Modulation (SVM) technique is projected to meet the torque and flux demands at low speeds. Findings: By designing 7 level NPC for DTC of induction motor and thereby simplifying the classical DTC method and in very particular this paper is minimizing the complications in Torque and Flux control at minimal speeds by decoupling the torque and flux controls and also reduces the ripples in current and torque profile. 7 level NPC is introduced in this paper which helps in eliminating the torque disturbances into minimum. The proposed 7 level inverter uses less number of switches and neutral-point fluctuations are absent in this model. Detached DC supplies are employed for the DC links which carries the ripple current. The proposed inverter topology provided the required magnitudes and phases of voltage and current vectors to meet the desired load values with fewer harmonic content due to superior level inverter and less distortion in torque profile obtained in the closed loop DTC technique.1 The DTC of Induction Motor simulated by implementing the SVM technique using 7 level NPC and the simulation results are experimentally validated.Improvements: The steady state torque and speed output have less ripple content which reduces the oscillation with a quick response at steady state was investigated.