Certain investigations and realization of svm dtc of induction motor drives using fpga

Abstract

Over the past two decades, technological advances in solid-state newlinepower electronics devices and high computation capability digital controllers, newlinevarious torque control schemes are becoming more popular in AC motor drive newlineapplications. Among all AC motors, Induction motors (IMs) play an important newlinepart in many different types of domestic and industrial applications that require newlinerapid torque response and high-performance operation. The popularity of the newlinemotor is due to its ruggedness and operational reliability. newline Field oriented control (FOC) and Direct torque control (DTC) are newlinebecoming industrial standards for induction motor torque control. Both newlineschemes provide a decoupled control of torque and flux during transients and newlinesteady state. However, FOC scheme requires current controllers, co-ordinate newlinetransformations and inner current loops which increase the complexity of the newlinescheme and degrade the dynamic performance. The DTC has been extensively newlineused in industrial applications with IM using two level three phase voltage newlinesource inverter with hysteresis controller due to some advantages like: more newlinesimplicity, low dependency on the motor parameters and good dynamic newlinetorque response. This type of drive system is named as conventional DTC. newlineHowever, the conventional DTC has some problems like more torque and flux newlineripples as well as harmonic content in the stator current. Hence, to overcome these problems in FOC and conventional DTC newlinea novel space vector modulated direct torque control (SVM-DTC) with low newlinepass filter (LPF) based torque and flux estimator for induction motor drive system is proposed. In the proposed scheme, the conventional switching table newlineand hysteresis controllers are eliminated, and a fixed switching frequency is newlineobtained with the help of SVM. Stator flux and torque of the motor are newlineestimated from an improved voltage model, which is based on a LPF. The newlinebasic theory of operation of proposed scheme is presented. The simulations newlineare carried out using MATLAB/SIMULINK simulation package.