Magnetically based sensorless switched reluctance drive for general purpose applications

Abstract

Shaft position transducers are commonly used to provide rotor position information for commutation of the switched reluctance (SR) motor and for excitation control. However, in low cost applications such as fans and pumps, particularly at low power levels, the shaft position sensor is too costly. Therefore, a simple sensorless position drive system is preferred. It is the aim of this article to present a simple sensorless rotor position measurement for a SR using the magnetization data of the motor windings. The proposed method is based on estimating a particular rotor position on a phase by phase basis and measuring flux linkage and current when the estimated position is reached. By comparing the measured flux linkage with the prestored flux linkage corresponding to the particular position for the measured current, the angular difference between the estimated position and the particular position can be calculated. The proposed sensorless SR drive system has been tested in the laboratory and its output performance was compared to the output of commercial system based on an optical sensor.