Faculty Publications
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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 Design and implementation of single phase inverter based on Cuk converter for PV system(International Journal of Renewable Energy Research, 2017) Sabhahit, N.S.; Gaonkar, D.N.; Anandh, N.; Kumar, N.S.In this paper, analysis and hardware implementation of a single phase inverter based on Cuk converter for PV system is presented. The buck-boost characteristic of such a converter promotes flexibility for both grid tied as well as standalone connections where the ac voltage is either higher than or lesser than the dc input voltage. Further Cuk based topologies have the better efficiency and voltage regulation, which is a lacking feature in a basic boost or a buck configuration. The proposed system not only offers continuous input and output current but also controlled voltage over a wider range. Hence this topology can serve as an expedient alternative converter stage for photovoltaic applications. In the proposed bidirectional two-switch Cuk converter, DSPIC30F2010 controller is used for controlling the duty ratio of switching pulses. Also, this controller generates PWM signals for the switches of single phase H-bridge inverter. The hardware results for the developed prototype of a Cuk converter based single phase inverter are presented. The developed scheme can easily be scalable to a much larger rating of the PV system.Item Improvement in Harmonic Reduction of a Zigzag Autoconnected Transformer Based 12-Pulse Diode Bridge Rectifier by Current Injection at DC Side(Institute of Electrical and Electronics Engineers Inc., 2017) Vidyasagar, V.; Kalpana, R.; Singh, B.; P, P.P.In this paper, to improve the harmonic reduction ability in the input line current of a 12-pulse diode bridge rectifier using zigzag autoconnected transformer with a dc side current injection technique is presented. Conventional 12-pulse rectifier does not meet the IEEE-519 standard and therefore current injection technique at dc side is used to shape the converter current to minimize the harmonic distortion in the input line current. The proposed converter configuration uses a zigzag autoconnected transformer with inherent ability to block zero-sequence components, which eliminates the requirement of a zero-sequence blocking transformer, and thereby reduces the overall rating of the converter. The current injection technique at dc side enables to alter the dc side currents, which further shapes the input line currents to near sinewave with total harmonic distortion of less than 1% and power factor close to unity. The proposed converter configuration is simulated and analyzed in MATLAB/Simulink. The effects of variation in the magnitude of injected current on the input line current harmonics in terms of power quality indices are analyzed. A prototype of the proposed converter configuration is developed, and experimental results are presented to validate the theoretical design, analysis, and simulation results. © 1972-2012 IEEE.Item Optoelectronic properties of hybrid diodes based on vanadyl-phthalocyanine and zinc oxide(Academic Press, 2017) Raveendra Kiran, M.R.; Ulla, H.; Satyanarayan, M.N.; Umesh, G.We report an investigation of the optoelectronic properties of a hybrid p-n diode device fabricated using ZnO film prepared by sol-gel technique on which a VOPc organic film is deposited by vacuum evaporation. The charge transport properties of devices having the configurations ITO/ZnO/Al and ITO/ZnO/VOPc/MoO3/Al were investigated at different annealing temperatures (150 °C, 250 °C, 350 °C and 450 °C) by Impedance Spectroscopy (IS). The structural, morphological, optical and electrical properties were also studied at different annealing temperatures. The parameters related to the ITO/ZnO and ZnO/VOPc interfaces such as ideality factor (n), barrier height (q?B) and rectification ratio (RR) of the diodes were determined from current density-voltage (J-V) characteristics. IS measurements suggest that the large photocurrent generated is due to the decrease in bulk resistance of the device on account of the generation of electron-hole pairs in the organic active layer when exposed to light. The RR and the photocurrent responsivity (Rph) values obtained from the J-V characteristics compare well with those obtained from the IS measurements. It was observed that the absolute value of Rph (470 mA/W) for the p-n diode with ZnO annealed at 350 °C is high compared to that of diodes with different ZnO annealing temperatures. These values also agree well with the values obtained for p-n diodes of other phthalocyanines. Our studies clearly demonstrate that a p-n diode with ZnO film annealed at 350 °C exhibits much better optoelectronic characteristics on account of increased grain size, improved charge injection due to the reduction of barrier height and hence higher (up to 5 orders) charge carrier mobility. © 2017 Elsevier LtdItem Implementation of Single-Phase Two-Switch Midpoint Unidirectional Multilevel Converter System(Walter de Gruyter GmbH, 2018) Roy, P.R.; Parthiban, P.; Babu, B.This paper deals with implementation of a single-phase three level converter system under low voltage condition. The frequency of the switches is made constant and involves change in $-t-on}}$ton and $-t-off}}$toff duration. For this condition the pulse width modulation control scheme for a single phase three level rectifier is developed to improve the power quality. The hysteresis current control technique is adopted to bring forth three-level PWM on the dc side of the bridge rectifier and to achieve high power factor and low harmonic distortion. Based on the proposed control scheme, the line current is driven to follow the sinusoidal current command which is in phase with the supply voltage. By using three-level voltage pattern the blocking voltage of each power device is clamped to half of the dc link voltage. The simulation and experimental results of 20W converter under low input voltage condition are shown to verify the circuit performance. Open loop simulation and hardware tests are implemented by applying a low voltage of 15 V(rms) on the input side. © 2018 Walter de Gruyter GmbH, Berlin/Boston 2018.Item A 20-Pulse Asymmetric Multiphase Staggering Autoconfigured Transformer for Power Quality Improvement(Institute of Electrical and Electronics Engineers Inc., 2018) P, P.; Kalpana, R.; Singh, B.; Bhuvaneswari, G.This letter presents a 20-pulse multiphase staggering autoconfigured transformer (MSAT) for power quality improvement in medium and high power applications. The proposed autoconfigured transformer is a combination of delta and zig-zag transformers. Contrary to the prior art multipulse autoconnected transformers, magnetic rating of the proposed configuration is only 40% of the load rating in addition to improved power quality indices. Moreover, the creation of a neutral point ascribed to inbuilt zig-zag windings supplements as one of the remarkable advantages of the proposed MSAT. Therefore, with this suggested configuration, the performance of zig-zag transformer is accomplished within the autoconfigured transformer. A detailed comparison of the proposed MSAT configuration with that of other multipulse autoconnected transformers in terms of magnetic rating and power quality indices are presented. Further, the feasibility and operability of the proposed MSAT are verified and validated through experimental tests on the laboratory prototype. The test results so obtained complies with the IEEE-519 and IEC 61000-3-2 standards on power quality requirements. © 2017 IEEE.Item Power Quality Enhancement Using Current Injection Technique in a Zigzag Configured Autotransformer-Based 12-Pulse Rectifier(Institute of Electrical and Electronics Engineers Inc., 2018) Kalpana, R.; Chethana, K.S.; P, P.; Singh, B.This paper proposes a DC-side circuit configuration that improves the harmonic suppression ability of a 12-pulse diode bridge rectifier (DBR) using a zigzag configured autotransformer. The DC-side circuit uses a single-phase DBR along with interphase transformer which generates the required circulating current thereby modifies the DC currents at the DBR output, in turn shapes the input line current near to a sine wave. The proposed single-phase DBR is connected in parallel with the load which enables to reuse the harmonic energy thus improving the energy conversion efficiency. The zigzag configured autotransformer used for 12-pulse DBR possesses the inbuilt ability to hinder the zero-sequence components, which expel the need of zero sequence blocking transformer. The proposed configuration is analyzed, simulated in MATLAB Simulink and the simulation results are presented, which confirm the reduction of total harmonic distortion (THD) in the input line current thereby improving the power quality under large load variations. Furthermore, the viability of the proposed configuration is verified by experimental results, which confirm the suitability of the proposed configuration in industrial applications. © 1972-2012 IEEE.Item Three-phase three-level boost-type front-end PFC rectifier for improving power quality at input AC mains of telecom loads(Korean Institute of Power Electronics editor@kipe.or.kr, 2018) P, P.; Kalpana, R.; Singh, B.A three-phase, three-switch, and three-level boost-type PWM rectifier (Vienna rectifier) is proposed as an active front-end power factor correction (PFC) rectifier for telecom loads. The proposed active front-end PFC rectifier system is modeled by the switching cycle average model. The relation between duty ratios and DC link capacitor voltages is derived in terms of the system input currents. Furthermore, the feasible switching states are identified and applied to the proposed system to reduce the switching stress and DC ripples. A detailed equivalent circuit analysis of the proposed front-end PFC rectifier is conducted, and its performance is verified through simulations in MATLAB. Simulation results are verified using an experimental setup of an active front-end PFC rectifier that was developed in the laboratory. Simulation and experimental results demonstrate the improved power quality parameters that are in accordance with the IEEE and IEC standards. © 2018, Korean Institute of Power Electronics. All rights reserved.Item Application of voltage multiplier in 12-pulse rectifier for sinusoidal input current(Institution of Engineering and Technology journals@theiet.org, 2018) P, P.; Kalpana, R.; Singh, B.; Bhuvaneswari, G.A DC current injection circuit of a trifurcated autotransformer (TAT)-based 12-pulse diode bridge rectifier (DBR) is proposed which can help reduction of harmonics in the AC mains. The circuit at the DC side employs a voltage multiplier (VM) circuits namely voltage doubler, voltage tripler and voltage quadrupler and an interphase transformer which provides the required circulating current. This induced circulating current shapes the input AC line current near to a sine wave. The output of VM circuits is connected across the load and thereby reuses the harmonic energy absorbed by the system. Thus, improves the energy conversion efficiency of the proposed system. The TAT-based 12-pulse DBR has the implicit ability to prevent the zero sequence components thus expels the necessity of zero sequence blocking transformer. The proposed configuration is analysed, simulated in MATLAB Simulink and the simulation results are presented, which confirms the improvement in power quality parameters in the input AC line current. Further, the viability of the proposed configuration is verified by experimental results which confirm the suitability of the proposed configuration in AC-DC applications. © 2018 Springer Verlag. All rights reserved.Item Asymmetric H-Bridge Single-Phase Seven-Level Inverter Topology with Proportional Resonant Controller(Taylor and Francis Ltd, 2019) Salodkar, P.A.; Kulkarni, P.S.; Waghmare, M.A.; Chaturvedi, P.C.; Sandeep, N.This paper presents an asymmetrical H-bridge single-phase seven-level inverter topology with modified gating scheme for reducing the number of high-frequency switches. Due to shortcomings like steady-state error and problems in removing low-order harmonics associated with proportional integral controller, proportional resonant controller is used for grid-connected converter current control. A practical application of proportional resonant current controller is developed using a low-cost dsPIC33EP256MC202 microcontroller to keep the current injected in to the grid. The validity of proposed inverter and control scheme is verified through simulation and implemented for low-voltage laboratory prototype. © 2017, © 2017 IETE.