Novel speed sensorless DTC-SVM scheme for induction motor drives

The article presents a novel DSP based high performance speed sensorless control scheme for PWM voltage source inverter-fed induction motor drive for city transportation. The modified Direct Torque Control with Space Vector Modulation (DTC-SVM) scheme has been selected because it eliminates disadvantages while keeping advantages of both FOC and classical DTC methods. Secondly, the simple MRAS based flux vector observer allowing speed sensor elimination is presented. The novelty of the presented system lays in combining the DTC-SVM structure with simple observer for both torque/flux and speed sensorless control including flux weakening range. Finally, the description of the 50 kW laboratory tram drive and experimental results illustrating properties of the system are given.