Rotor Position Sensing and Estimation Techniques for Switched Reluctance Motors: Overview

Abstract

Switched Reluctance Motors (SRMs) are fast gaining attraction towards industrial applications since they are less costly in construction and have robust performance in harsh environments. However, for speed, current and torque control in SRMs, rotor position sensing is indispensable. Over the last decade, there have been extensive research on rotor position determination using different techniques. Discrete sensors and indirect rotor position estimation both have merits and drawbacks depending on speed ranges, size of motor and principle of operation. This paper will analytically classify and discuss different techniques applied under rotor position estimation. These techniques are compared with regards to complexity of mathematical models, estimation error, complexity of the algorithm and need for storage memory. Additionally, this work also discusses rotor position determination using sensors with a proposition of a new technique using Magnetostrictive Amorphous Wire. Instead of the conventional position sensor encoders to sense the position of the rotor pole, this scheme proposes the application of Magnetostrictive Amorphous Wire (MAW) as the position sensor. The conventional position sensor is expensive and unreliable. It has been found to be affected by vibrations, temperature fluctuations, dirt and dust. With proper physical arrangement, the MAW sensor has been proven to provide amplifiable signals from the rotor. The discussion is geared towards facilitation in selection of potentially effective techniques in rotor position sensing and estimation in SRM drives.