Evaluation of a novel analog based closed-loop sensorless controller for switched reluctance motor drive

A novel analog closed-loop controller for a four-phase switched reluctance motor (SRM) in variable speed drive applications, dispensing with position and speed sensors, has been proposed in this paper. The scheme is based on comparing the active current of a phase with a closed-loop switching reference current (I/sub oref/) with the intention of switching-on and switching-off the other phase in the pair, which comprises of two stator phases, whose L/sub min/-zones do not overlap. This technique requires no parameter measurement and/or estimation and without prior knowledge of stator flux-linkage variation. The paper also includes an analog controller with position sensors to evaluate the developed sensorless controller. A detailed simulation study of both the drive systems, supported by experimental steady-state and transients results, are presented to validate the proposed technique. A double polynomial-fit is used in the simulation study to describe the nonlinear magnetization characteristics of the SRM. The performance of the sensorless drive is excellent and is in good agreement with the drive with position sensors.