Direct torque control of induction motors fed by a single frequency converter

Abstract

Direct torque control of an induction motor is established by survey of operation regimes of traction electric drives to thoroughly satisfy the requirements for a traction electric drive. The advantages and shortcomings of three-level voltage source inverters in locomotive traction electric drives are highlighted in relation to two-level ones. A mathematical model of a multimotor system fed by a single frequency converter based on direct torque control is developed. It is shown that the variables of an induction motor can be represented as the sum of its average value and deviation from it. The equations for stator flux linkage and torque of an induction motor have been developed for a two-motor system fed by a single voltage source inverter. The topology and principles of operation of direct torque control of induction motors with a three-level voltage source inverter are described. The simplified structure and mathematical model of the mechanical part of a traction drive using basic and axle suspension are considered. The results of simulation carried out by Matlab are shown.