Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
18 results
Search Results
Item An integrated Control Approach and Power Management of Stand-alone Hybrid Wind/PV/Battery Power Generation System with Maximum Power Extraction Capability(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2015) Sabhahit, N.S.; Gaonkar, D.N.The production of electricity from renewable energy sources like wind and photovoltaic energy has increased in recent years, due to environmental problems and the shortage of traditional energy sources. In this article we present a detailed mathematical model and a control scheme for hybrid wind and PV based DG system with battery and maximum power extraction capability for isolated mode of operation. The wind power generation system uses wind turbine (WT), a permanent magnet synchronous generator (PMSG), a three-phase diode rectifier bridge, DC/DC boost converter with maximum power point tracking (MPPT) controller. The PV generation system uses PV array, a boost converter with maximum power point tracking controller. Both sources and battery are connected to common dc bus with a dc link capacitor and supply power to load through PWM voltage source inverter. The overall control system consists of MPPT controller for both Wind and PV power system, a bi-directional DC-DC converter controller for battery energy storage management and load side inverter controller for voltage and frequency regulation. Control strategies for individual system components of the proposed system are designed with a view to achieve an acceptable level of voltage and frequency regulation while extracting the maximum power from wind and PV system. The performance of the developed hybrid system is investigated in terms of voltage and frequency regulation capability under changing wind, solar irradiation and variable load conditions.Item Performance analysis of a variable-speed wind and fuel cell-based hybrid distributed generation system in grid-connected mode of operation(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Ayyappa, S.K.; Gaonkar, D.N.This article presents the performance study of a variable-speed wind and solid oxide fuel cell-based hybrid distributed generation system, along with the energy storage devices in the grid connected mode of operation. The developed model has a salient feature of utilizing fluctuating output power of wind systems to produce hydrogen and also to charge the ultra capacitor. The presented model in the article also uses the stored energy in the ultra capacitor to compensate for the slow response time of the fuel cell. The distributed generation systems and energy storage devices considered in this study are integrated at common distributed generation links to form the hybrid system. The hybrid system is interfaced to the grid through the three-phase voltage source inverter in this article. The detailed modeling of the individual components of the hybrid distributed generation system, along with the necessary power electronic converter control schemes, are presented. The simulation results reported in this article show the effective performance of the hybrid model to produce reliable, low-cost electricity and hydrogen from the variable wind generation system. © 2016 Taylor & Francis Group, LLC.Item Utilization of low computational cost two dimensional analytical equations in optimization of multi rings permanent magnet thrust bearings(Electromagnetics Academy chew@jpier.org Suite 207777 Concord Avenue Cambridge, MA 02138, USA 02138 Massachusetts, 2017) Bekinal, S.I.; Doddamani, M.; Dravid, N.D.Replacement of conventional bearings by passive magnetic bearings for high-speed applications, in terms of their performance will be effective, if the design is carried out by optimizing the geometrical dimensions in the given control volume. Present work deals with modification and utilization of two-dimensional (2D) analytical equations in optimization of multi rings permanent magnet (PM) thrust bearing configurations. Conventional and rotational magnetized direction (RMD) configurations are selected in optimizing the design variables for maximum bearing characteristics in a given volume with a constant aspect ratio. The design variables chosen for optimization are axial offset of rotor, number of rings, radial air thickness and inner diameter of the rotor and stator PM rings. MATLAB codes for solving 2D equations are developed in optimizing configuration variables. Further, optimized parameter values of the two configurations are compared. Finally, optimized results obtained using 2D and three-dimensional (3D) equations for the conventional configuration with same aspect ratio are compared, and conclusions are presented. © 2017, Electromagnetics Academy. All rights reserved.Item Design and performance analysis of quantitative feedback theory based automated robust controller: An application to uncertain autonomous wind power system(AIMS Press, 2018) Gudimindla, G.; Manjunatha, S.K.Use of a robust controller for handling the operational uncertainties has become imperative in real time. This paper presents a modified fitness function based automated robust controller with the aid of quantitative feedback theory (QFT) using Genetic algorithm (GA). A controller exhibiting the desired decreasing modular plot and descending phase response is devised. The addition of arctangent function as one of the fitness function term is the proposed modification that facilitates in capturing the ideal controller characteristics. The proposed controller is applied to extract maximum power from a permanent magnet synchronous generator based autonomous wind power system. The step by step design guidelines for the automated QFT robust controller is deliberated in detail. The performance evaluation is carried out for step change and stochastically varying wind speed. Finally, benchmarking of the proposed controller against those available in the literature is accomplished through extensive simulations and it will be shown that the maximum power extraction along with least electromagnetic torque oscillations are achieved with the proposed fitness function based automated QFT controller. © 2018 the Author(s).Item Generalized optimization procedure for rotational magnetized direction permanent magnet thrust bearing configuration(SAGE Publications Ltd info@sagepub.co.uk, 2019) Bekinal, S.I.; Doddamani, M.; Vanarotti, M.; Jana, S.Optimization of rotational magnetized direction permanent magnet thrust bearing configuration is carried out using generalized three-dimensional mathematical model. The bearing features namely axial force and stiffness are maximized using in-house developed mathematical expressions solved using MATLAB. The design variables selected for the optimization are axial offset, number of ring pairs, air gap and inner radius of inner and outer rings. The maximized axial force values of the optimized configuration are validated with the finite element analysis results. To overcome the high computational cost associated with three-dimensional equations, generalized method of optimization is sucessfully demonstrated using plots representing variation of optimal design variables as a function of air gap with respect to bearing’s outer diameter. Simple and useful method of using the generalized plots for the process of optimization is presented by dimension optimization of representative bearing configuration with a particular aspect ratio. The proposed optimization using mathematical model and generalized approach assists designer in selecting optimized geometrical parameters of rotational magnetized direction thrust bearing configurations easily for variety of high-speed applications. © IMechE 2018.Item Laboratory implementation of electromagnetic torque based MRAS speed estimator for sensorless SMPMSM drive(Institution of Engineering and Technology JBristow@theiet.org, 2019) Koothu Kesavan, K.; Karthikeyan, A.; Blaabjerg, F.This Letter proposes a simple electromagnetic torque based model reference adaptive system (MRAS) speed estimator for sensorless surface mount permanent magnet synchronous motor (SMPMSM) drive. The proposed estimator is formed using instantaneous measured and estimated electromagnetic torque. The proposed estimator is implemented for 1.5 kW laboratory prototype SMPMSM drive using field programmable gate array ALTERA cyclone II. Experimental results demonstrate the efficacy of the proposed scheme under different test conditions viz. different low-speed regions and standstill at different load conditions with uncertainty in machine parameters. Results show that the estimator is stable in low-speed regions and exhibits robustness against uncertainties in machine parameters. © The Institution of Engineering and Technology 2019Item FPGA based direct torque control with speed loop Pseudo derivative controller for PMSM drive(Springer, 2019) Karthikeyan, A.; Koothu Kesavan, K.; Nagamani, C.This paper presents a comprehensive evaluation of proposed speed loop pseudo derivative feedback (PDF) controller based DTC with speed loop PI based direct torque controller (DTC) for permanent magnet synchronous motor (PMSM) drive. The proposed PDF-DTC system significantly improves dynamic response i.e. completely eliminates overshoot in speed, reduces 50% overshoot in electromagnetic torque and has two times faster settling time compared to PI-DTC system during step changes in speed with load disturbance. The proposed controller is verified for different cases viz., speed variation at constant load and variation in the load torque at constant speed. The proposed controller is implemented for 1.5 kW laboratory prototype PMSM drive using FPGA ALTERA cyclone II. Experimental results demonstrates the efficacy of the proposed controller. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.Item Improvement in the design calculations of multi-ring permanent magnet thrust bearing(Electromagnetics Academy, 2020) Bekinal, S.I.; Doddamani, M.This article presents the design and optimization of multi-ring permanent magnet thrust bearing (PMTB) with an axial air gap between successive axial stacks. Larger air gap due to the inclusion of conductive materials needs to be critically analysed in permanent magnet bearings with eddy current damper. High conductivity materials can be filled in an axial air gap instead of a radial air gap to increase the required amount of damping. Three-dimensional (3D) mathematical model for load-carrying capacity for the said configuration is presented using the Coulombain model. The significance of an axial air gap between successive ring pairs in the configuration concerning maximization in the bearing characteristics is presented. Variables such as the number of axial stacks, an axial air gap between the successive rings, an inside radius of rotor ring magnets, and an inside radius of stator ring magnets are optimized at different air gap values for maximizing the load-carrying capacity and stiffness. A significant increase in the values of bearing characteristics is observed in the optimized configuration as compared to bearing with a single permanent magnet ring pair. Optimized PMTB with comparable load carrying capacity and stiffness values can be used to replace conventional bearings used in high-speed applications to improve system efficiency. © 2020, Electromagnetics Academy. All rights reserved.Item Optimum Design Methodology for Axially Polarized Multi-Ring Radial and Thrust Permanent Magnet Bearings(Electromagnetics Academy, 2020) Bekinal, S.I.; Doddamani, M.This article deals with the generalized procedure of designing and optimizing multi-ring radial and thrust permanent magnet bearings (PMBs) with an axial air gap for maximum force andstiffness per volume of the magnet. Initially, the procedure of determining optimized design variables inboth the configurations is presented using the MATLAB codes written for solving the three dimensional(3D) equations of force and stiffness in PMB having ‘n’ number of rings on the stator and rotor. Themaximized results of the forces in both radial and thrust multi-ring PMBs are validated with the valuesobtained using finite element analysis (FEA). Then, the correlation between the optimized parametersand the air gap is obtained, and curve fit equations for the same are proposed in terms of stator outerdiameter. Further, curve fit equations establishing the relationship between the maximized bearingfeatures, and the aspect ratio (L/D4) of the bearing are expressed for different values of air gap inboth the radial and thrust bearings. Finally, the generalized method of designing and optimizing themulti-ring PMB is demonstrated with a specific application. A designer can use the presented curvefit equations for optimizing design variables and calculating maximized bearing features in multi-ringradial and thrust PMBs easily just by knowing the bearing features for a single ring pair. © 2020. All Rights Reserved.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.