Sensorless sliding mode control of SVPWM fed induction motor drive using dss speed estimator

Abstract

This paper proposes a highly improvised and a vibrant sensorless vector control of the three-phase induction motor drive, brought out by a combination of sliding mode control and Space vector pulse width modulated inverter, with “Direct synthesis from State Equations” (DSS) as the technique for estimating speed. Field oriented Vector control method of decoupling the flux and torque and controlling them separately analogous to a separately exited dc motor, is taken as the key control technique in this model. To overcome the drawbacks of physical sensors, ‘Direct synthesis from state equations’ (DSS), a Sensorless speed estimation technique is used, which estimates the rotor speed by determining the flux from the stator currents and voltages. The control side is taken over by the ‘Sliding mode Controller’ which provides a non-linear and robust control insensitive to the external disturbances, parameter uncertainties and the dynamic load variations. Lastly, SVPWM based Voltage source inverter is used where the inverter output comes with reduced harmonics. Thus a nearly smooth sinusoidal output ac voltage is obtained, which is fed to the induction motor. From the simulation of this proposed combination of techniques, a smooth speed control is achieved. Respective graphical outcomes to prove the characteristics of the proposed control system are included in this paper.