Generation of Control Strategy for Sensorless Vector Controlled Induction Motor Drive

Abstract

Machines plays an important role in day to day life of people . Without machines no work is possible e.g without a generator the electricity cannot be produced, without motor the mobility of heavy objects would be a tedious job, similarly there are various applications of machines.The machines cannot be operated on own and if it is not used properly it can destroy the things. Similar is for an induction motor if not controlled properly can cause damage.DC drives are easy to control were more preferable for industrial application but due to high maintenance and commutation problems they were sidelined by ac drives. 90% of industry uses induction motor as they have simple construction and easy to maintain with a disadvantage of sluggish response to speed change. The main problem with motors is to control its speed . There are various methods to control speed of induction motor viz. 1). Stator Voltage control 2). Rotor resistance control 3). V/f control. The above mentioned methods give the speed control but have disadvantages of sluggish response. Advent of vector control ac machines has revolutionized the eld of ac drives, it has solved lots of problems of scalar methods. Vector control gives you the control of ac motor as a dc motor i.e. you can control the ux component and torque component of current individually. Vector control requires shaft mounted speed encoder for position sensing which is costly and have reliability issues. It is possible to sense speed signal from machine terminal voltages and currents using a DSP. Sensorless induction motor drives are popular because of their exibility, reliability and can be easily used in hostile conditions. There are various methods for speed estimation in Induction motor viz. (1) Slip calculation, (2) Direct synthesis from state equations, (3) Model referencing adaptive system (4) Extended Kalman Filter, (5) Slot harmonics, (6) Injection of auxiliary signal on salient rotor. In the proposed project control strategy for sensorless vector controlled induction motor drive will be simulated and from simulated results it will be implemented.