Faculty Publications
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Publications by NITK Faculty
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Item Speed loop pseudo derivative feedback controller based direct torque controlled permanent magnet synchronous motor drive(Institute of Electrical and Electronics Engineers Inc., 2017) Koothu Kesavan, K.K.; Venkatesa Perumal, B.V.; Karthikeyan, A.; Nagamani, C.This paper presents a comprehensive evaluation of PI controller and proposed pseudo derivative feedback (PDF) controller based direct torque controlled (DTC) permanent magnet synchronous motor (PMSM) drive. The proposed controller eliminates oscillation and overshoot in the actual rotor speed and significantly reduces the flux, torque and stator current ripples. The performance of the proposed controller is tested for different cases viz., no load starting response, load variations at rated speed, wide speed reversal and low speed regions including standstill condition at rated torque. The simulations are carried out through MATLAB/Simulink environment for 1.2hp PMSM drive and results demonstrates the efficacy of the proposed controller. © 2016 IEEE.Item Pseudo derivative feedback current controlled sensorless PMSM drive with flux-Torque based MRAS estimator for low speed operationestimator for low speed operation(Institute of Electrical and Electronics Engineers Inc., 2017) Karthikeyan, A.; Koothu Kesavan, K.K.; Venkatesa, P.B.; Nagamani, C.In this paper, a simple and robust speed estimator and Pseudo Derivative Feedback (PDF-PDF) controller are proposed for sensorless PMSM drive to improve its performance at standstill and low speed regions. The speed estimator is formed using stator flux and electromagnetic torque based model reference adaptive system, which performs better during transient conditions and reduces steady state error for wide rotor speed variations which includes low speed regions. The proposed PDF-PDF controller reduces the overshoot and improves settling time of the system. The stability of the proposed estimator is verified through small signal model and the machine parameter sensitivity is also analyzed. The performance of the proposed estimator and controller is validated by considering variation in the low speed regions which includes standstill condition. The simulations are carried out through MATLAB/Simulink and it is also experimentally verified through FPGA controller based 1.2hp laboratory prototype PMSM drive. It is found that the maximum estimated rotor speed and position error are ±2 rad/s and ±1° respectively during low speed operation at transient and steady state conditions. ©2017 IEEE.Item Four quardrant operation of direct torque controlled PMSM drive using speed loop PDFF controller(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Koothu Kesavan, K.K.; Nagamani, C.This paper presents a comprehensive evaluation of proposed speed loop pseudo derivative feedforward (PDFF) controller based DTC, speed loop PI based direct torque controller (DTC) and speed loop PI based hysteresis current controller (HCC) for permanent magnet synchronous motor (PMSM) drive. The proposed controller reduces the torque and stator current ripples and significantly reduces overshoot and oscillation in the actual rotor speed. The proposed controller is verified for different cases viz., forward and reverse motoring, forward and reverse braking operation. The simulations are carried out through MATLAB/Simulink for 1.2 hp PMSM drive and results demonstrates the efficacy of the proposed controller. © 2018 IEEE.Item Standalone single stage PV fed reduced switch inverter based independent control of two PMSM drive(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Koothu Kesavan, K.K.; Abhilash Krishna, D.G.; Nagamani, C.This paper proposes a standalone singe stage PV fed air cooler which consists of two motors (fan blower and water pump). The proposed system comprises of PV source, reduced switch inverter and two PMSM drive. The proposed system aims at reducing the switching losses and overall cost by using reduced switch inverter. The reduced switch inverter uses only eight switches whereas the conventional VSI utilizes twelve switches. In the proposed scheme, blower and pump are independently controlled using field oriented control scheme where speed reference is obtained using Perturb and Observe (PO) technique. Simulation studies for the proposed PV fed two 400 W PMSM driven blower and pump is performed using MATLAB platform and respective results are presented to show the efficacy of the system. © 2018 IEEE.Item Uncertainity and disturbance estimator based control of transformerless DVR(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Abhilash Krishna, D.G.; Kurra, S.; Koothu Kesavan, K.K.This paper presents Uncertainty and Disturbance Estimator (UDE) based control for Transformerless Dynamic Voltage Restorer (TDVR). The proposed UDE based control algorithm for TDVR mitigate the voltage disturbances and maintain robustness during parameter (filter) variations. The control equation of UDE is derived based on the dynamic model of a voltage source inverter along with the LC filter. The proposed UDE control estimates the uncertainties and disturbances by an appropriate filter (loop filter involved in the derived UDE control law) and used for further synthesis, thus accounts for robustness. The simulation studies are performed for 230 V low voltage (LV) system in MATLAB to verify the efficacy of UDE control for symmetric and asymmetric voltage sags along with the parameter mismatch (inverter filter) conditions. © 2018 IEEE.Item Single stage PV fed reduced inverter based PMSM for standalone water pumping application(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Koothu Kesavan, K.K.; Varsha, S.; Venkatesa Perumal, B.; Mishra, S.This paper proposes a standalone PV fed PMSM drive for water pumping. The proposed system aims at reducing the switching losses and overall cost by using reduced switch inverter. The proposed system comprises of a PMSM drive, fed by PV source through an inverter employing reduced number of switches. The inverter uses only four switches whereas the conventional VSI utilizes six switches. Field oriented control scheme is employed to control the PMSM drive. Perturb and Observe (PO) MPPT technique is used to generate a speed reference to PMSM drive. Simulation studies for the proposed PV fed 400 W PMSM driven water pumping system are performed using MATLAB platform and respective results are presented to show the efficacy of the system. © 2018 IEEE.Item Stator flux based MRAS speed and stator resistance estimator for sensorless PMSM drive(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Koothu Kesavan, K.K.; Nagamani, C.In this paper, a simple and robust speed and stator resistance estimator is proposed for sensorless permanent magnet synchronous motor drive to improve its performance at standstill and low speed regions. The speed and stator resistance estimator is formed using stator flux based model reference adaptive system, which yields fast transient response, reduces steady state error for low rotor speed variation and load disturbances. The proposed method improves the performance of the drive at low speed regions. The simulations are carried out through MATLAB/Simulink environment and results show the effectiveness of the sensorless PMSM drive. The maximum estimated rotor speed and position error are found to be are ±3 rad/s, ±1 °respectively, during low speed operation at transient and steady state conditions. © 2017 IEEE.Item Hybrid Control of Single-Phase to Three-Phase Reduced Switch Converter for PMSM Drive(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Varsha, S.; Koothu Kesavan, K.K.This paper proposes hybrid control for single phase to three phase reduced switch converter based PMSM drive that can be used in remote locations where only single phase grid is available. PI, hybrid (hysteresis+ PI) controllers are employed for controlling the input and output sides of the converter respectively. This configuration for PMSM drive has a shared leg between output and input sides. The input side PI controller synchronizes input grid current with the grid voltage to maintain unity power factor during load and speed variations. This configuration has unity input power factor and allows bidirectional power flow. The proposed system is modeled for 400W motor in MATLAB/SIMULINK environment and the simulation results are presented. © 2018 IEEE.Item PV fed Hybrid Power Converter for rural home applications(Institute of Electrical and Electronics Engineers Inc., 2019) Karthikeyan, A.; Praneeth, C.V.S.; Koothu Kesavan, K.K.This paper proposes a standalone PV fed hybrid power converter for rural home applications. The aim of the proposed system is to simultaneously deliver the power extracted from PV panels to DC and AC home loads using the proposed hybrid converter topology. The system operates in either MPP or Non-MPP mode depending on the total power demanded by the loads. Modified Perturb and Observe (PO) MPPT algorithm is used to extract maximum power from PV panels. SPWM based modified PWM technique is used for converter operation. In the MPP mode the power distribution to DC load and AC load is in accordance with the duty generated by modified MPPT. In Non MPP mode, power distribution is in accordance with the duty generated by the single loop voltage control for DC load. The simulation studies for the proposed system are carried out in MATLAB/SIMULINK environment. © 2019 The Korean Institute of Power Electronics (KIPE).Item Critical review of PV grid-tied inverters(MDPI AG indexing@mdpi.com Postfach Basel CH-4005, 2019) Kavya Santhoshi, B.K.; Mohanasundaram, K.M.; Padmanaban, S.; Holm-Nielsen, J.B.; Koothu Kesavan, K.K.Solar Photovoltaic (PV) systems have been in use predominantly since the last decade. Inverter fed PV grid topologies are being used prominently to meet power requirements and to insert renewable forms of energy into power grids. At present, coping with growing electricity demands is a major challenge. This paper presents a detailed review of topological advancements in PV-Grid Tied Inverters along with the advantages, disadvantages and main features of each. The different types of inverters used in the literature in this context are presented. Reactive power is one of the ancillary services provided by PV. It is recommended that reactive power from the inverter to grid be injected for reactive power compensation in localized networks. This practice is being implemented in many countries, and researchers have been trying to find an optimal way of injecting reactive power into grids considering grid codes and requirements. Keeping in mind the importance of grid codes and standards, a review of grid integration, the popular configurations available in literature, Synchronization methods and standards is presented, citing the key features of each kind. For successful integration with a grid, coordination between the support devices used for reactive power compensation and their optimal reactive power capacity is important for stability in grid power. Hence, the most important and recommended intelligent algorithms for the optimization and proper coordination are peer reviewed and presented. Thus, an overview of Solar PV energy-fed inverters connected to the grid is presented in this paper, which can serve as a guide for researchers and policymakers. © 2019 by the authors.