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Degree

Doctor of Philosophy, University of Akron, Engineering, 2005.

Abstract

The excitation of the switched reluctance motor (SRM) phases needs to be carefully synchronized with rotor position to obtain an acceptable drive performance. Therefore, rotor position sensing is an integral part of the SRM drives control. Additionally, for precise torque and speed control applications, it is necessary to have rotor position information with reasonably good resolution and high degree of accuracy. Sensorless control methods are an attractive approach in which the rotor position is sensed indirectly without a discrete mechanical position sensor. In the past, several methods have been developed to replace the discrete position sensor. Some of these methods are inductance based while others are flux based. Unfortunately, all of them were confined with the estimation to a limited range of speed and for only one quadrant operation. This dissertation develops a four-quadrant sensorless controller for SRM drives functioning over low and high speeds, including zero speed, with a high resolution position information over the entire speed range. This four-quadrant sensorless controller combines two different methods. At zero and low speeds, a pulse injection position estimation method is used to estimate the rotor position in all four quadrants. At high speeds, a sliding mode observer (SMO) based position and speed estimation is used and combined to work with the low speed algorithm. The transition between the algorithms is smooth and transparent to the inner loop torque controller. The accuracy and resolution of the sensorless controller developed in the research has been enhanced through the use of a novel switched reluctance (SR) machine model based on the Fourier series expansion that is accurate and invertible. This model, derived from machine geometry and materials properties, is accurate enough to be used for actual machine representation, and can also be simplified for real time sensorless controller application. The model predicts both the inductance and flux linkage accurately for use in various sensorless control algorithms. The experimental tests performed showed accurate position estimation using the new Fourier model. The error analysis performed in this research demonstrated the superiority of the Fourier model over the models developed in previous research.

Keywords

Switched Reluctance Motors; Sensorless Control; Wide Speed Range; Modeling

Advisor

Iqbal Husain

Pages

171p.

Document number: akron1123088518
Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=akron1123088518

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