Modified direct torque control for sensorless asynchronous motor fed by three-level inverter

Abstract

Direct Torque Control is a well-known high-performance technique used in asynchronous motors. This conventional technique which uses hysteresis comparators suffers from high torque ripples and variable switching frequency. The most common solution to those drawbacks is to use the modulation technique in order to have a constant frequency. This paper presents a modified direct torque control of asynchronous motor scheme associated to sinusoidal pulse width modulation and PI regulators to generate the system voltages. In the other hand and instead of using a two-level inverter, the asynchronous motor is fed by a three-level inverter in order to reduce stress of the power device and to enhance output quality. In addition, the control strategy uses a speed estimator that allows the elimination of the mechanical sensor, which greatly increases the reliability of the system. To evaluate the performance of the proposed method, theoretical principles and simulation results using the MATLAB / SIMULINK software will be made.