Keywords: indirect vector control, space vector modulation, SVM, diode clamped inverters, two–level inverter, performance improvement, torque ripple, induction motor drives, inverter control
Performance improvement of indirect vector controlled induction motor drive using multi–level inverter
Multi–level inverter has emerged as an important topology in the area of high power–medium voltage control applications due to its several advantages such as a better output voltage with reduced total harmonic distortion (THD), reduction of voltage ratings of the power semiconductor switching devices and also the reduced electro–magnetic interference problems etc. This paper presents the performance of an indirect vector controlled induction motor drive fed from five–level, three–level and two–level inverters under different operating conditions (dynamic and steady state). The control scheme uses space vector modulation (SVM) technique for five–level, three–level and two–level inverter circuits. For two–level inverter control, an SVM algorithm in which the calculation of switching times proportional to the instantaneous values of the reference phase voltage. It eliminates the calculation of sector and angle information. For three–level and five–level inverter control, a simplified SVM technique is implemented, which reduces the coordinate transformations complications in the algorithms. In this, the space vector diagram of the three–level and five–level inverter is decomposed into six space vector diagrams of two–level inverters. The torque ripple and the performance of induction motor drive with three–level, five–level and two–level inverters are compared under different operating conditions.