Review of Different Speed Estimation schemes for Sensorless Induction Motor Drives

Abstract

Induction motor drives without direct speed sensors have the features of low cost, high reliability, better noise immunity and less maintenance requirements. Therefore, there is a great interest in the research community to develop a high performance induction motor drive that does not require a direct speed sensor for its operation; that is to develop a speed-sensorless induction motor drive. The information required for rotor speed estimation is extracted from measured stator voltages and currents at the motor terminals. Different speed estimation algorithms are used for this purpose. The main concerns regarding speed estimation are related to steady state accuracy, dependency on motor parameters, estimation bandwidth and dynamic behavior. This paper presents a comprehensive study of the different speed estimation techniques and their corresponding merits and demerits as well as their feasibility for estimating the rotor speed. The different speed estimation methods are compared according to a proposed set of criteria which allow assigning the merits that can be used to choose the proper method, depending on the specific application.