Speed sensorless direct torque control for three-level diode-clamped inverter fed induction motor using adaptive flux observer

In this paper, a speed-sensorless direct torque control (DTC) drive for induction motor (IM) is developed using three-level inverter and a comprehensive study is presented. Firstly, three-level neutral-point clamped (NPC) inverter is handled and the switching vectors used in DTC based on switching table are defined. Second, the adaptive flux observer is utilized to estimate the rotor speed and load torque. Observer model of IM is obtained from the equations of IM in stationary reference frame and adaptive scheme for speed estimation is given in detail. The objective of this study is to present a drive system implemented simply and easily. The proposed drive system is verified by the simulation results.