Faculty Publications
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Publications by NITK Faculty
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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.Item Design and optimization of an external-rotor switched reluctance motor for an electric scooter(Elsevier Ltd, 2023) Bhaktha, S.B.; Jogi, A.; Jeyaraj, J.; Gangadharan, K.V.In order to reduce the global carbon foot print, the need of the hour is to provide pollution free and economically viable electric vehicles (EVs) as potential alternatives to the conventional ones. Amongst the different traction motors employed in EVs, switched reluctance motors (SRMs) being magnet-free, rugged in construction and fault-tolerant is a potential forerunner for automotive applications in the near future. Therefore, in this work, an external-rotor (ER) SRM has been designed for an electric scooter application. The proposed 4-phase SRM configuration comprises of 8 and 10 poles on the stator and rotor respectively. To achieve a well-balanced design with due consideration to the various performance indicators, a multi-objective design optimization (MOO) has been performed using particle swarm optimization (PSO). The optimization was based on the results obtained from the two-dimensional (2D) electromagnetic static finite element analysis (FEA) which aimed to maximize average torque, efficiency and minimize torque ripple respectively. In comparison to the preliminary design, the optimized ER-SRM demonstrated an increased average torque and decreased copper loss by 3% and 14% respectively. The large scale of simulations performed and the results thereby obtained confirmed that the proposed SRM design met the performance demands of the electric scooter application. The average torque at the rated and the maximum speed exceeded the desired torque requirements demanded by the electric scooter by 13.1% and 42.2% respectively. © 2023Item Design and Performance Analysis of a Switched Reluctance Motor Using Finite Element Analysis and Magnetic Equivalent Circuit Model(Defense Scientific Information and Documentation Centre, 2023) Bhaktha, S.B.; Kumawat, S.; Jeyaraj, J.; Gangadharan, K.V.By being magnet-free, and mechanically robust with a longer constant power range, switched reluctance motor (SRM) is gathering much attention as a potential choice to propel electric vehicles (EVs) and hybrid electric vehicles (HEVs). This paper comprehensively investigates the performance sensitivity to geometric design variables such as rotor diameter, pole arc angles, and yoke thicknesses for an SRM using static two-dimensional (2D) electromagnetic Finite-Element Analysis (FEA). The reason for the change in static characteristics due to variation in reluctance between SRM designs has not been detailed previously. This is addressed by the magnetic equivalent circuit (MEC) model that simplifies the design analysis. Results indicate that stator pole reluctance needs to be given due importance while studying the influence of rotor diameter. Also, it is imperative to set an adequate thickness of the stator and rotor yokes to minimize the effect of saturation on the performance. Rotor diameter and stator pole arc angle have a pronounced influence on the performance while the influence of rotor pole arc angle and yoke thicknesses was relatively less. © 2023, DESIDOC.Item Driving Cycle-Based Design Optimization and Experimental Verification of a Switched Reluctance Motor for an E-Rickshaw(Institute of Electrical and Electronics Engineers Inc., 2024) Bhaktha, B.S.; Jose, N.; Vamshik, M.; Pitchaimani, J.; Gangadharan, K.V.This article deals with the design and optimization of a 2 kW switched reluctance motor (SRM) for an electric rickshaw (E-rickshaw). Previously published research on SRM optimization has mostly focused on the optimization of their design and control variables only at the rated conditions. In electric vehicle (EV) applications, the load operating points (LOPs) of a traction motor are dynamic and spread widely across the torque speed envelope. To enhance their overall performance, it is vital to include them in the design optimization process; therefore, in this article, a novel procedure for implementing the multiobjective design optimization (MODO) of an SRM based on a driving cycle has been demonstrated. Higher starting torque and torque density with reduced electromagnetic losses throughout the driving cycle are established as the design objectives, subject to practical restrictions on current density and slot fill factor. The design objectives have been accurately evaluated through transient finite element analysis (FEA) and a computationally efficient SRM drive model (developed in MATLAB/Simulink) with consideration of the excitation control parameters. Kriging models have been constructed to reduce the computation cost of FEA during the optimization process. Then, a nondominated sorting genetic algorithm II (NSGA II) based multiobjective optimization coupled with the constructed Kriging models is conducted to generate a Pareto front. An optimal design that offers the best balance between the design objectives is selected from the Pareto-optimal set, and the dimensions of corresponding design variables are used to build a prototype. Finally, the static and dynamic performance of the SRM prototype are experimentally evaluated and validated with the FEA simulations. © 2024 IEEE.Item A Systematic Approach to Digital Control Development for Four-Phase SRM Drive Using Single Current Sensor for Medium Power Applications(Institute of Electrical and Electronics Engineers Inc., 2024) Ali, T.F.; Dominic D, D.A.; Prabhakaran, P.In the realm of medium-power high-volume applications, Switched Reluctance Motor (SRM) drives hold great advantages over other motors. However, the SRM drive must be optimized to reduce cost without compromising the performance for medium power applications. This paper presents a novel SRM drive utilizing a Miller converter-fed SRM motor with a single current sensor, offering a comprehensive control development procedure encompassing system modeling, design procedures, dynamic simulation, analysis, and experimental validation. The SRM is characterized through finite element analysis (FEA) to derive a MATLAB Simulink simulation model, and the conduction angle is optimized for drive efficiency through parametric simulation studies. The linear SRM model for control design is obtained via small signal analysis. Speed and current controllers are designed using the K-factor method, and the efficacy of the proposed drive is rigorously evaluated across various operating modes in MATLAB Simulink. Additionally, a hardware prototype is developed and the digital control algorithm is implemented on the DSP microcontroller TMS320F28379D based on the designed controllers to further assess drive performance. The results obtained validate the robustness and dynamic performance of the SRM drive across variable speed, variable torque, and constant power modes of operation. © 2013 IEEE.Item Fault-Tolerant Operation of Switched Reluctance Motor Using Cascaded Current and PWM Control With Effect of Commutation Angle Variation(Institute of Electrical and Electronics Engineers Inc., 2024) Reddy, J.S.; Parthiban, P.This paper presents a proposed fault-tolerant control strategy for Switched Reluctance Motor (SRM) drives, utilizing cascaded current and pulse width modulation (PWM) control mechanisms with commutation angle variation. The study systematically evaluates the mechanical performance of SRM drives by regulating voltage and current to achieve robust dynamic response under various fault conditions. Optimal commutation angles are identified to enhance operational efficiency and balance performance under fault scenarios. The comprehensive simulations use a 4 kW, 4 φ, 8/6 SRM model in MATLAB/Simulink; further, real-time experiments are conducted using FPGA-based modelling with a Controller Hardware-in-Loop (CHIL), setup on the OPAL-RT 4510 platform. The proposed control technique demonstrates high fault tolerance and reliable mechanical performance, making it suitable for variable-speed drive applications. The findings underscore the potential of the proposed control strategy to ensure the robust operation of SRM drives in practical implementations, highlighting its significance for enhancing the reliability and efficiency of electric drive systems. © 1972-2012 IEEE.Item A Bidirectional Interleaved Totem Pole PFC-Based Integrated On-Board Charger for EV SRM Drive(Institute of Electrical and Electronics Engineers Inc., 2024) Faheem Ali, T.; Arun Dominic, A.D.; Prabhakaran, P.; Parameswaran, A.P.This paper presents an improved integrated on-board charger (IOBC) tailored for a 4-phase switched reluctance motor (SRM) drive. The proposed IOBC is non-isolated and utilizes the totem pole power factor correction (PFC) operation for reduced common-mode voltage. Furthermore, the proposed system accommodates bidirectional functions, ensuring versatility during charging mode. A non-isolated IOBC for SRM with reduced common-mode voltage and bidirectional capability has largely been ignored in the literature. The proposed system utilizes a modified Miller converter in the motoring mode and is easily reconfigured into a two-phase interleaved totem pole converter during charging modes without the need for any magnetic contactors. The proposed system features zero instantaneous torque (ZIT) at steady-state, ensuring minimal machine wear during charging modes. The proposed IOBC is controlled to ensure symmetric positive and negative grid currents for any given rotor position (during charging), thereby eliminating even harmonics and enhancing the power quality of grid current. The proposed system achieves charging power twice the motoring power with parallel-connected phase windings. Ansys electromagnetic transient simulation, MATLAB-based SRM drive simulations, experimental results, and comprehensive comparative analysis are presented to validate the various features and effectiveness of the proposed IOBC for SRM. © 2013 IEEE.Item Analyzing the Performance of Fault-Tolerant Switched Reluctance Motor Control Strategies With Novel Commutation Angle Variation(Institute of Electrical and Electronics Engineers Inc., 2024) Santhosh Reddy, J.; Parthiban, P.This paper analyzes control techniques using a novel commutation angle variation for fault-tolerant operation in Switched Reluctance Motor (SRM) drives. It explores the use of hard chopping hysteresis current control (HCC) and pulse width modulation (PWM), and proposes a cascaded current and PWM technique for fault-tolerant SRM drive operation. The HCC method is most effective for low-speed operations with higher external loads, while the PWM method is suitable for medium to high-speed operations but it can't control current effectively at high external loads. The proposed control technique approach is developed to address the limitations of HCC and PWM methods, by combining current and PWM methods with optimized commutation angle control. This approach effectively controls current and variable speed operations even under fault conditions. This paper evaluates control strategies by varying commutation angles to determine the optimized angles that ensure balanced performance and better operation under fault conditions. This paper assesses the mechanical performance under light and high external loading conditions at optimized commutation angles during open circuit fault conditions. Simulation studies are conducted using a 4 kW, 4-phase, 8/6 SRM configuration on the MATLAB/Simulink platform. Additionally, real-time FPGA-based modelling experiments are performed using a Controller Hardware-in-Loop (CHIL) setup on the OPAL-RT 4510 platform. The performance analysis highlights the importance of identifying the best control techniques to ensure high fault tolerance and reliable mechanical performance, making this approach promising for variable-speed drive systems. The findings of this study significantly advance fault-tolerant SRM control techniques, enhancing their suitability for various industrial applications. © 2013 IEEE.