An auto-calibrating model for an 8/6 switched reluctance motor drive: application to design and control

Development of a precise dynamic model for switched reluctance motors (SRM) is a critical step in design and analysis of optimal control strategies. This paper is focused on important issues concerning the development of such models and their subsequent use in designing control strategies for the SRM drive. The main goal in modeling is to provide a good accuracy over the entire speed and torque range. To achieve this objective, the following requirements need to be met: (1) a good accuracy in following the inductance of each stator phase, (2) inclusion of mutual effects when significant overlap among phases exists, (3) inclusion of short flux path operation in each electrical cycle when significant overlap among adjacent phases exists, and (4) capability for auto-calibration to cope with parameter variations caused by manufacturing imperfections and operational conditions. In this paper, we present a precise modeling approach along with an auto calibration strategy. A simple yet elegant test collects the necessary data for developing the proposed model. Inherent separation among mechanical, electrical and control time constants have been used to develop the auto-calibration process. Our modeling approach takes into account the effects of short flux path in each electrical cycle as well as effects of overlap inductances at high speeds. This, in turn, results in further enhancement of the accuracy in predicting the dynamic response of the SRM drive when significant overlap among phases exists.