| PhD Viva

Name of the Speaker: Mr. Arun Chithrabhanu (EE15D212)
Guide: Prof. Krishna Vasudevan
Online meeting link: https://krishnavasudevan.my.webex.com/krishnavasudevan.my/j.php?MTID=m5d92dae65a1dca2df4007fe30d090938
Date/Time: 5th April 2024 (Friday), 3:00 PM
Title: Control techniques and converter topologies for the reduction of torque ripple and vibration in a switched reluctance motor drive.

Abstract

In recent days, there has been considerable interest in permanent magnet-free motors for electric vehicular propulsion owing to economic and logistical considerations. The switched reluctance motor is a suitable candidate for this as they are simple to construct, cheap, fault-tolerant, and possesses good torque characteristics. However, the major impediments that limit the use of SRM in vehicular or other high-performance applications are torque ripple and vibration. The torque ripple in SRM is predominantly due to the pulsed manner of phase excitation with non-linear torque characteristics. The vibration is primarily attributed to the circumferential deformations occurring due to the radially acting electromagnetic forces that are inherent in the machine along with the torque-producing tangential forces. A simultaneous control of torque ripple and vibration is cumbersome as both are of electromagnetic origin and depend on the instantaneous phase currents and rotor positions. Any control of one parameter would result in losing the degree of control on the other. It has been identified that vibration can be effectively reduced by reducing the rate of change of the radial forces. Further, an increased phase demagnetization voltage helps to improve the phase commutation and thereby reduce the torque ripple.

This thesis presents (i) an online compensation scheme and a simplified control strategy for the reduction of torque ripple in SRM with less computational complexity, (ii) a new torque sharing functionality (TSF), and an angle selection strategy for TSF-based control for the reduction of vibration without compromising the torque ripple reduction. In addition, this thesis also presents a modified C-dump converter with a buck-boost energy recovery stage which can achieve a higher demagnetization voltage with lesser voltage ratings of the energy recovery stage as compared to its conventional counterparts. A four-level shared switch converter is also proposed, which can achieve a higher demagnetization voltage with an even further reduction in the voltage rating of the energy recovery capacitor, with the additional advantage of soft-chopping. The topology, operating modes, and salient features of the converters are presented in detail. All the works mentioned above are demonstrated using simulation and experimental studies.