Asenkron motor hızının sensörsüz olarak belirlenmesi

Abstract

The induction motor is the most widely used electrical motor in industrial applications. The majority of induction machines are used in constant speed drives, but during the last decades the introduction of new semiconductor devices has made variable speed drives with induction machines available.Variable speed induction motors are usually fed by open loop frequency inverters. The rotor speed of the machine is not measured, and a change in load torque will result in a change in speed. The dynamic performance is weak and problems such as oscillations are common.All those properties are obtained with vector controlled induction machines The drawback of this method is that the rotor speed of the induction machine must be measured, which requires a speed sensor of some kind, for example a resolver or an incremental encoder. The cost of the speed sensor, at least for machines with ratings less than 10 kW, is in the same range as the cost of the motor itself. The mounting of the sensor to the motor is also an obstacle in many applications. A sensorless system where the speed is estimated instead of measured would essentially reduce the cost and complexity of the drive system.This work focuses on observers estimating speed for induction machines.