| PhD Seminar

Name of the Speaker: Mr. Arun Chithrabhanu (EE15D212)
Guide: Prof. Krishna Vasudevan
Online meeting link: https://krishnavasudevan.my.webex.com/meet/krishna
Date/Time: 15th December 2023 (Friday), 11:00 AM
Title: Buck-boost energy recovery based power converters for the reduction of torque ripple in SRM drives

Abstract

In this seminar, two converter topologies for SRM that can achieve a higher demagnetization voltage across phases, to reduce the commutation torque ripple, are presented. From analytical studies, it has been inferred that increasing the phase demagnetization voltage reduces the torque ripple occurring in SRM during phase commutations. There have been several topological options envisaged in the literature to achieve an increased demagnetization voltage. The energy recovery-based power converters are one class of such converters, where a capacitor bank and an intermediate DC/DC converter stage are interfaced between the phases and the DC link, to achieve the desired demagnetization voltage. The first topology presented in this talk is a modified C-dump converter. Unlike the conventional C-dump converter, the proposed converter has a buck-boost energy recovery stage. With this arrangement, a demagnetization voltage of -2Vdc can be achieved by maintaining the recovery capacitor at 2Vdc itself, unlike a conventional C-dump converter, where the capacitor needs to be maintained at 3Vdc. This reduces the size and cost of the converter. Further, the effects of the discontinuous conduction mode of operation of the BBERC on the drive performance are discussed. Additionally, the advantages of BBERC are re-emphasized by comparing it with other energy recovery-based topologies such as energy-efficient C-dump converter.

The second topology is an energy recovery-based four-level shared switch converter topology. The proposed converter has a shared switch diode pair common for a pair of phases non-overlapping in conduction. An energy recovery stage with a buck-boost DC/DC converter is employed to recover the stored magnetization energy of phases back to the DC source. With the arrangement proposed in the paper, the converter can achieve a double demagnetization voltage by maintaining the capacitor voltage of the energy recovery stage at Vdc, which is considerably lower than that of the other energy recovery converter counterparts. Further, the proposed FLSSC is capable of operating the SRM drive in soft-chopping mode, resulting in a lesser ripple in the phase current during single-phase conduction and also a reduced high-frequency ripple in the torque.

The operation of the proposed converters and their effectiveness in generating higher demagnetization voltage, and the analyses presented are demonstrated using simulation and experimental studies.