PhD ThesisThe recent growing interest in Switched Reluctance Drives (SRD) is due to the electrification
of many products in industries including electric/hybrid electric vehicles, more-electric
aircrafts, white-goods, and healthcare, in which the Switched Reluctance Machine (SRM) has
potential prospects in satisfying the respective requirements of these applications. Its main
merits are robust structure, suitability for harsh environments, fault-tolerance, low cost, and
ability to operate over a wide speed range. Nevertheless, the SRM has limitations such as large
torque ripple, high acoustic noise, and low torque density. This research focuses on the torque
control of the SRD with the objectives of achieving zero torque error, minimal torque ripple,
high reliability and robustness, and lower size, weight, and cost of implementation.
Direct Torque Control and Direct Instantaneous Torque Control are the most common methods
used to obtain desired torque characteristics including optimal torque density and minimized
torque ripple in SRD. However, these torque control methods, compared to conventional
hysteresis current control, require the use of power devices with a higher rating of about 150%
to achieve the desired superior performance. These requirements add extra cost, conduction
loss, and stress on the drive’s semiconductors and machine winding. To overcome these
drawbacks, a simple and intuitive torque control method based on a novel adaptive quasi sliding mode control is developed in this study. The proposed torque control approach is
designed considering the findings of an investigation performed in this thesis of the existing
widely used control techniques for SRD based on information flow complexity.
A test rig comprising a magnet assisted SRM driven by an asymmetric converter is constructed
to validate the proposed torque control method and to compare its performance with that of
direct instantaneous torque control, and current hysteresis control methods. The simulation and
experimental results show that the proposed torque control reduces the torque ripple over a
wide speed range without demanding a high current and/or a high switching frequency. In
addition, It has been shown that the proposed method is superior to current hysteresis control
method in the sensorless operation of the machine. Furthermore, the sensorless performance of
the proposed method is investigated with the lower component count R-Dump converter. The
simulation results have also demonstrated the excellent controller response using the standard
R-Dump converter and also with its novel version developed in this thesis that needs only one
current sensor