Sensorless and direct torque control for polyphase induction drive

The modern technique of direct torque control induction motor is modified in this paper. Machine analysis is emphasized directly on the 3-phase variables for motoring mode, so Park´s transformation to generalized d-q axis theory is not used. Only stator current signal is functioning to evaluate fluxes and speed, so that no need to use any sensor. The 3-phase PPU inverter gate is excited by the control signals and power supply with a triangular carrier wave, and dc link to the collector. Flux, torque and speed are the control signals. The system model is designed on the Matlab using typical parameters of PID controller, and all resulting core variables are observed. Curves are plotted for torque, speed and voltages, which are seen to be accurate with low ripple, less distortion and establishing high efficiency