Faculty Publications
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Publications by NITK Faculty
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Item A novel CSI-fed induction motor drive(2006) Beig, A.R.; Ranganathan, V.T.Current source inverter (CSI) fed drives are employed in high power applications. The conventional CSI drives suffer from drawbacks such as harmonic resonance, unstable operation at low speed ranges, and torque pulsation. This paper presents a novel CSI drive which overcomes all these drawbacks and results in sinusoidal motor voltage and current even with CSI switching at fundamental frequency. The proposed CSI drive uses a three-level inverter as an active filter across motor terminals replacing the bulky ac capacitors used in the conventional drive. A sensorless vector controlled CSI drive based on proposed configuration is developed. The simulation and experimental results are presented. Experimental results show that the proposed drive has stable operation even at low speeds. Comparative results show that the proposed CSI drive has improved torque ripple compared to the conventional configuration. © 2006 IEEE.Item Modified SVPWM algorithm for three level VSI with synchronized and symmetrical waveforms(2007) Beig, A.R.; Narayanan, G.; Ranganathan, V.T.The objective of the present work is to improve the output waveform of three level inverters used in high-power applications, where the switching frequency is very low. This is achieved by maintaining the synchronization, half-wave symmetry, quarter-wave symmetry, and three-phase symmetry in the pulsewidth modulation (PWM) waveforms. The principles of achieving synchronization and symmetries in terms of space vectors for three level inverters are presented. A novel synchronized space vector pulsewidth modulation (SVPWM) algorithms is proposed and verified experimentally. The experimental waveforms of the inverter output voltage and motor no load current for different operating conditions of the drive are presented. The performance measure in terms of the weighted total harmonic distortion (THD) of the line voltage is computed for the linear modulation region of the drive for the proposed algorithm and compared with that of synchronized SVPWM and synchronized sine-triangle pulsewidth modulation (SPWM) technique. The comparative results show that consideration of synchronization and symmetry results in improved THD. Another significant feature of the proposed algorithm is that the symmetry and synchronization leads to self-balancing of the direct current (dc) bus capacitor voltages over every one third cycle of the fundamental. © 2007 IEEE.Item Synchronized symmetrical bus-clamping PWM strategies for three level inverter: Applications to low switching frequencies(2011) Veeranna, S.B.; Yaragatti, U.R.; Beig, A.R.The digital control of three-level voltage source inverter fed high power high performance ac drives has recently become a popular in industrial applications. In order to control such drives, the pulse width modulation algorithm needs to be implemented in the controller. In this paper, synchronized symmetrical bus-clamping pulse width modulation strategies are presented. These strategies have some practical advantages such as reduced average switching frequency, easy digital implementation, reduced switching losses and improved output voltage quality compared to conventional space vector pulse width modulation strategies. The operation of three level inverter in linear region is extended to overmodulation region. The performance is analyzed in terms THD and fundamental output voltage waveforms and is compared with conventional space vector PWM strategies and found that switching losses can be minimized using bus-clamping strategy compared to conventional space vector strategy. The proposed method is implemented using Motorola Power PC 8240 processor and verified on a constant v/f induction motor drive fed from IGBT based inverter. © 2011 Berkeley Electronic Press. All rights reserved.Item Direct torque controlled induction motor drive based on cascaded three two-level inverters(Acta Press, 2014) Thippiripati, T.V.; Surapaneni, S.S.In this paper, a new and an effective voltage switching-state algorithm to Direct Torque Control (DTC) of induction motor drive is proposed, which makes less torque and flux ripple at various operating frequency conditions. In conventional DTC, the torque and flux ripples are difficult to reduce as the applied voltage vector is independent of rotor speed especially at low speeds. To overcome this problem, the proposed technique introduces a voltage switching-state algorithm for four-level inversion using cascading three two-level inverters, in which choice of inverter voltage states is the function of rotor speed. From simulation results, the torque and flux ripple are decreased with proposed DTC when compared with the conventional DTC technique at various operating frequencies.Item 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 Electromagnetic torque-based model reference adaptive system speed estimator for sensorless surface mount permanent magnet synchronous motor drive(Institute of Electrical and Electronics Engineers Inc., 2020) Koothu Kesavan, K.K.; Karthikeyan, A.This article proposes simple and robust electromagnetic torque-based model reference adaptive system speed estimator with cascaded pseudoderivative feedback controller for sensorless surface mount permanent magnet synchronous motor (SMPMSM) drive to improve its performance at standstill and low-speed regions. The proposed estimator is formed using instantaneous and estimated electromagnetic torque. Using small signal modeling, the stability and sensitivity analysis are performed. Results show that the estimator is stable over a wide speed region (including low-speed regions) and exhibits robustness against uncertainties in machine parameters. The proposed estimator is implemented for the 1.5-kW laboratory prototype SMPMSM drive using field programmable gate array (FPGA) ALTERA Cyclone II. Experimental results demonstrate the efficacy of the proposed scheme under different test conditions viz., over a wide adjustable speed range which includes different low-speed regions and standstill, i.e., 157 to -157 rad/s at different load conditions with uncertainty in machine parameters. © 1982-2012 IEEE.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 Implementation of Different Drive Topologies for Control of Induction Motor for Electric Vehicle Application(River Publishers, 2022) Husain, M.A.; Rajput, R.; Gupta, M.K.; Tabrez, M.; Ahmad, M.W.; Ilahi Bakhsh, F.I.To improve driving range in Electric vehicles (EV), parallel-series connection of battery cells is a necessity. Supressing the circulating current in the battery board of parallel connected battery strings helps improve the lifespan of the batteries. This study presents a comparison of the requirements of parallel strings of batteries in three different popular topologies for open end winding induction motor (IM) drives in EV. The topologies analyzed are a 3-phase voltage source inverter (VSI), a Dual fed inverter and three single-phase HBridge VSIs. These converters are modulated using Space vector pulse width modulation (SVPWM) as it has better performance compared to Sine PWM. MATLAB-Simulink models are developed for the converter topologies. The simulation results show that the three single-phase inverter topology feeding the drive is the best alternative when compared on the basis of battery requirement and switch loss. Moreover, each H-bridge inverter (in the three single-phase inverter topology) can be used as charger and the problem of circulating current during charging will also be least as compared to other schemes. © 2022 River Publishers.Item Efficiency analysis of dual motor powertrain with planetary gear set(Walter de Gruyter GmbH, 2023) Mishra, S.; Dominic D, D.A.; Mudliyar, K.; Divakar, M.This paper focuses on electric vehicles with dual motors combined with a planetary gear train. The combination of sun and ring motor allows for achieving higher efficiencies and satisfying power demands as compared to single motor powertrains. Primarily dual motor drive with planetary gear train is proposed and simulated with different drive cycles. Secondarily by extracting the motor efficiency maps working area of different modes, speed and efficiency are determined. Finally, an optimization algorithm was developed to automatically change speed and torque as per load demand. In this way, our work could represent a framework for improving efficiency performances and load demands of an electric vehicle. © 2022 Walter de Gruyter GmbH, Berlin/Boston.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.