Faculty Publications
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Item New direct torque and flux control with improved torque per ampere for switched reluctance motor(Institute of Electrical and Electronics Engineers Inc., 2019) Pittam, K.R.; Ronanki, D.; Parthiban, P.; Williamson, S.S.Inherent torque ripple, acoustic noise and vibration are the major hindrances of switched reluctance motor (SRM)for wide acceptance in the automotive industry. To avoid stability issues in electrified vehicles, smooth torque control of an SRM is requisite. Torque ripple in the SRM can be avoided by proper machine design and/or directly controlling the torque. To maintain the torque within the hysteresis band in the conventional direct torque and flux control (DTFC), a high value of RMS current flows through the motor windings. This results in an increase in copper losses and reduces the net torque per ampere ratio. This paper addresses this issue by proposing a new DTFC technique for an SRM drive with the features of improved torque per ampere while maintaining the torque within the hysteresis bands. MATLAB simulations show that the proposed DTFC technique enhances torque per ampere ratio while minimizing the torque ripple. The effectiveness of the proposed DTFC strategy is also demonstrated through real-time simulations in the OPAL-RT digital platform. Real-time results show that the proposed DTFC strategy exhibits better performance in comparison to the conventional DTFC under steady-state and dynamic conditions. © 2019 IEEE.Item Torque Ripple Minimization of Four-phase Switched Reluctance Motor using Direct Torque Control with an Innovative Switching Sequence Scheme(Institute of Electrical and Electronics Engineers Inc., 2019) Pittam, P.K.; Ronanki, D.; Parthiban, P.; Beig, A.R.; Williamson, S.S.Direct torque control (DTC) technique is the prominent control strategy, used to control the switched reluctance motor (SRM) with a reduced torque ripple in comparison to the traditional current control techniques. However, it draws higher phase current in order to maintain the required electromagnetic torque during phase commutation, thus reduces torque per ampere. To circumvent this issue, a new DTC method with an innovative switching sequence is introduced in this paper, which minimizes torque ripple as well as power loss. The efficacy of the proposed scheme is validated for four-phase SRM through detailed simulation studies and compared with the conventional DTC scheme. The results show that the proposed scheme exhibits an improved steady-state as well as dynamic performance under various operating conditions. © 2019 IEEE.Item Phase current reconstruction algorithm for four-phase switched reluctance motor under direct torque control strategy(Institute of Electrical and Electronics Engineers Inc., 2021) Ronanki, D.; Pittam, K.R.; Dekka, A.; Parthiban, P.; Beig, A.R.Existing phase current reconstruction algorithms are developed for switched reluctance motor (SRM) operated under current chopping control (CCC), which generates high torque ripple. Therefore, the direct torque control (DTC) technique is mostly used to control the SRM with minimal torque pulsations. However, the reconstruction of phase currents using the existing one or two sensor methods developed under CCC control will be more difficult to adopt for the DTC scheme due to the simultaneous conduction of all phases. To circumvent this issue, a novel DTC method with reduced sensors is introduced in this paper, which exhibits better performance in comparison to the conventional DTC method. The proposed DTC method avoids the long tail currents thereby limits the conduction of all phases simultaneously. The efficacy of the proposed scheme is validated for four-phase SRM through MATLAB simulations. The results show that the proposed approach helps to operate the drive at the lower torque ripple with reduced cost under various operating conditions in comparison to the conventional DTC. © 2021 IEEE.Item Direct torque and flux control of switched reluctance motor with enhanced torque per ampere ratio and torque ripple reduction(Institution of Engineering and Technology JBristow@theiet.org, 2019) Krishna Reddy, P.; Ronanki, D.; Parthiban, P.A smooth torque control of switched reluctance motor (SRM) is essential to avoid speed fluctuations causing stability problems in vehicular applications. This can be accomplished by an appropriate motor design and/or use of direct control of torque in SRM. It is reported that high RMS current is required to minimise the torque ripple in the conventional direct torque and flux control (DTFC), thereby reducing the torque per ampere ratio. To overcome this issue, a new DTFC technique with improved torque per ampere ratio while minimising torque ripple in an SRM traction drive is presented. Results demonstrated that the proposed DTFC technique reduces torque ripple with enhanced torque per ampere. Finally, the performance of the proposed scheme is compared with conventional DTFC of a four-phase (8/6) SRM to show the improvement in the traction drive. © The Institution of Engineering and Technology 2019Item Efficiency improvement and torque ripple minimisation of four-phase switched reluctance motor drive using new direct torque control strategy(Institution of Engineering and Technology kvukmirovic@theiet.org, 2020) Pittam, P.K.; Ronanki, D.; Parthiban, P.The direct torque control (DTC) strategy is one of the most effective techniques, used to control the switched reluctance motor (SRM) with improved dynamic performance and reduced torque ripple. However, this approach draws a higher source current due to an extension of the phase current into the negative torque region, which lowers the net torque per ampere ratio. This study proposes a new DTC strategy for SRM to overcome this issue by modifying the partition of the sectors and appropriate voltage vector selection. Therefore, the proposed method improves the drive efficiency while minimising torque ripple. To implement this method, a non-linear machine model is developed using the torque and flux characteristics obtained from experimental studies on a four-phase 8/6 SRM. The proposed DTC scheme is implemented on a digital control platform and power loss calculations are performed to evaluate the drive efficiency. Test results show that the proposed DTC method has improved performance in terms of efficiency and torque ripple under various operating conditions in comparison to the conventional DTC strategy. © The Institution of Engineering and Technology 2019.Item Phase Current Reconstruction Method With an Improved Direct Torque Control of SRM Drive for Electric Transportation Applications(Institute of Electrical and Electronics Engineers Inc., 2022) Ronanki, D.; Pittam, K.R.; Dekka, A.; Parthiban, P.; Beig, A.R.Acquisition of the accurate phase currents is indispensable for the control and protection of switched reluctance motor (SRM) drives for electric transportation applications. Existing phase current reconstruction techniques for SRM are implemented under the current control techniques, which generate large torque pulsations. Therefore, the direct torque control (DTC) method can be adopted to minimize torque pulsations and to enhance transient performance in electrified vehicles. However, the existing current estimation methods cannot be applied to DTC strategies due to the simultaneous conduction of all phases at any switching instant. Furthermore, it offers a lower torque per ampere ($T/A$) ratio and draws a high source current. This article addresses the aforementioned concerns by proposing a cost-effective phase current reconstruction method with an improved DTC strategy for a 4-kW four-phase SRM drive. This method employs a 16-sector partition method with a new voltage vector selection by detecting zero-current regions of each phase. As a result, the long-tail currents can be avoided, thereby limiting the simultaneous conduction of all phases. The simulation and test results show that the proposed DTC has minimal torque pulsations, high $T/A$ ratio, low converter losses, and lower source current ripple in comparison to the existing DTC schemes under various operating conditions. Also, the proposed phase current estimation method effectively reconstructs the phase currents under both steady-state and transient operating conditions. © 1972-2012 IEEE.