Faculty Publications
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Publications by NITK Faculty
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Item A Zero Index Based Meta-Lens Loaded Wideband Directive Antenna Combined with Reactive Impedance Surface(Institute of Electrical and Electronics Engineers Inc., 2018) Majumder, B.; Kandasamy, K.; Ray, K.P.In this paper, an aperture efficient wideband high-gain patch antenna is designed using a novel multilayer-based metamaterial structure combined with a reactive impedance surface (RIS)-backed patch antenna. The metamaterial unit cell is a two-layer structure which is stacked one after other to form the overall unit cell. The microscopic behavior of the proposed unit cell has been investigated. This unit cell gives low refractive index over a wide bandwidth with a negligible loss. An RIS-backed patch antenna has been designed in the required frequency band to feed the multilayer zero-index metamaterial medium. The introduction of this surface is to provide unidirectional radiation over a wideband in the zero refractive index region. The proposed antenna gives a 14% fractional bandwidth over the $C$ - and $X$ -bands. The proposed antenna enhances the peak gain of the conventional patch antenna by an amount of 8.5 dB at 8 GHz. Finally, the antenna has been fabricated and its performance is verified experimentally. © 2013 IEEE.Item A 1.8 V 8.62 µW Inverter-based Gain-boosted OTA with 109.3 dB dc Gain for SC Circuits(Taylor and Francis Ltd, 2019) Kaliyath, Y.; Laxminidhi, T.This paper presents a low-power inverter-based gain-boosted operational transconductance amplifier (OTA) for switched capacitor (SC) circuits operating at higher supply voltage (>1 V). The proposed OTA is implemented using UMC 180 nm CMOS technology with a supply voltage of 1.8 V and it offers a high dc gain with a unity gain bandwidth (UGB) suitable for audio applications. All the transistors of the proposed OTA are operated in sub-threshold region to minimize the power consumption. Gain-boosting technique is employed to achieve a higher dc gain. The post-layout simulations demonstrate the robust performance of the proposed OTA, which delivers a high dc gain of 109.3 dB and a UGB of 5.29 MHz at 81° phase margin (PM) with a capacitive load of 2.5 pF for a typical process corner at room temperature (27°C). The proposed OTA draws a quiescent current ((Formula presented.)) of 4.79 µA, resulting in a power consumption of 8.62 µW. © 2019, © 2019 IETE.Item Slot coupled dual band high gain circularly polarized metasurface antenna(John Wiley and Sons Inc, 2022) Tharehalli Rajanna, P.K.; Rudramuni, K.; Kandasamy, K.This article presents a slot coupled dual-band metasurface (MTS) based antenna with high gain and circular polarization characteristics. The MTS consists of two different unit cells, which give rise to two operating bands. The metasurface is excited by the slot aperture fed by a 50 Ω microstrip feed-line. The circular polarization is achieved by the diagonally oriented rectangular patch-based unit cells on top of the square substrate. Two orthogonal modes of MTS are required to produce circularly polarized waves, and these modes are excited by the slot aperture. The proposed MTS-inspired antenna is fabricated and experimentally validated. The experimentally verified impedance bandwidth of 33.71% in the lower frequency band and 5.35% in the upper-frequency band is achieved. The measured 3 dB (AR <3 dB)axial ratio bandwidth of 6.22% and 0.98% with a peak gain of 8.89 and 6.32 dBic is achieved with respect to 4.8 and 6.4 GHz resonant frequencies. © 2022 Wiley Periodicals LLC.Item A non-isolated bidirectional high gain integrated multiport converter for grid tied solar PV fed telecom load(John Wiley and Sons Inc, 2023) Sheeja, V.; Kalpana, R.; Singh, B.; Subramaniam, U.; Muhibbullah, M.A multiport converter (MPC) with a non-isolated high gain bidirectional port is proposed for the grid integration of solar photovoltaic array (SPA) fed telecommunication load. The SPA along with a battery energy storage (BES) meets the power demand of the telecom DC load and the excess/deficit power is exchanged with AC grid. The MPC feeds the DC link of a voltage source converter for bidirectional operation with the AC grid. The small signal analysis of the converter shows that its operation is stable. The SPA, BES, and telecommunication load are rated for lower voltages, consecutively reducing the complexity with series-connected SPA. The proposed MPC possesses the merits of high voltage gain, reduced inductor size, and reduced number of components. Moreover, a power flow management algorithm is devised for the proposed converter that regulates the DC voltage at the telecom load and ensures smooth power flow control among various ports. The MPC is able to operate at various modes by controlling the ports independently. The converter performance during steady state and dynamic operating conditions under various modes are analyzed with detailed simulation studies. An experimental prototype is developed and test results are demonstrated to prove the viability of the designed converter. © 2022 The Authors. IET Power Electronics published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology.Item A Novel Bidirectional Modified Zeta Converter With Wide Voltage Conversion Ratio(Institute of Electrical and Electronics Engineers Inc., 2025) Mandal, S.; Prabhakaran, P.High-gain, nonisolated bidirectional dc–dc converters (BDCs) play a vital role in interfacing energy storage systems with microgrids and electric vehicles (EVs). However, the existing converters often operate within a limited duty cycle range and involve high component counts and significant voltage stress for achieving desired voltage gain. This article presents a novel noncoupled high-gain BDC that efficiently operates in the boost mode for forward power flow and buck mode for reverse power flow. Based on a modified zeta converter topology, the proposed converter offers a simplified circuit structure and control strategy, requiring fewer components. It achieves wide voltage gain across an extended duty cycle range while minimizing voltage stress on most switches. A 200-W prototype has been developed and tested in the laboratory to validate the converter’s performance. To enhance efficiency, SiC MOSFETs are utilized, achieving a peak efficiency of 96%. Experimental results confirm the converter’s suitability for both open-loop and closed-loop configurations, highlighting its potential for diverse applications in energy storage systems and EVs. © 2013 IEEE All rights reserved.Item Investigation and Performance Evaluation of Novel Single-Switch High-Gain DC-DC Converters for DC Microgrid Applications(Institute of Electrical and Electronics Engineers Inc., 2025) Diwakar Naik, M.; Vinatha Urundady, U.; Naik, M.; Bonthagorla, P.K.This paper introduces a novel single-switch, non-isolated high-gain DC-DC converter for solar photovoltaic (PV) and fuel-cell (FC) applications. These energy sources typically provide a continuous supply of current, necessitating a high-gain DC-DC converter that operates in continuous conduction mode (CCM). This converter draws a continuous input current from the supply and delivers a continuous output current to the load. The performance of the converter is thoroughly analyzed through the development of a state-space model and the derivation of the small signal transfer function, which helps in understanding the converter’s dynamic behavior. Detailed comparisons with existing converters are also presented. Furthermore, an output voltage controller is designed using the k-factor method to effectively regulate the output voltage without requiring a current sensor, even in the presence of input voltage variations. To validate the effectiveness of the converter and its controller, a 150 W prototype was constructed and experimentally verified in a laboratory setting. © 2013 IEEE.Item Single-Switch Continuous Current High-Gain DC-DC Converter with Common Ground for Vehicular Applications(Institute of Electrical and Electronics Engineers Inc., 2025) Shetty, S.; Prahllada, A.M.; Vinatha Urundady, U.Efficient power conversion is essential for integrating fuel cells into hybrid vehicles, where high voltage gain, minimal switching devices, high efficiency, and low input current ripple are critical for performance. This paper presents a high-gain quadratic boost DC-DC converter tailored for fuel cell hybrid vehicles, utilizing a switched inductor-capacitor technique with a clamping circuit to reduce voltage stress while maintaining a common ground structure. The converter’s operation, component design, and controller development are analyzed in detail, with comparisons to existing high-gain topologies. A 400V, 200W prototype was constructed and tested under varying supply and load conditions, achieving a maximum efficiency of 93.5% with a gain of 13.33 at 58% of rated power. To validate its performance, a 20% step change in the input voltage was tested, demonstrating a robust transient response. This aligns with practical fuel cell systems, where reactant partial pressure regulation typically keeps input voltage variations within 20%. Experimental results confirm the converter’s scalability for fuel cell vehicle applications, underscoring its potential to advance sustainable automotive technologies. © 2013 IEEE.Item A Transformerless Bidirectional Active Switched Inductor-Based SEPIC High-Gain DC–DC Converter With Buck–Boost Capability(Institute of Electrical and Electronics Engineers Inc., 2025) Mandal, S.; Prabhakaran, P.; Dominic, D.A.; Parameswaran, A.P.The growing demand for efficient and compact power conversion systems in electric vehicles (EVs), renewable energy systems, DC microgrids, and both portable and stationary medical equipment has intensified research into non-isolated high-gain bidirectional DC-DC converters. Existing solutions often employ transformer-based topologies or coupled inductors, which introduce increased cost, size, and control complexity. This paper presents a novel transformerless bidirectional high-gain DC-DC converter based on a modified Single-Ended Primary Inductor Converter (SEPIC) architecture. The proposed topology incorporates an Active Switched Inductor (ASL) at the input stage to achieve a wide voltage conversion ratio while ensuring reduced voltage stress on the maximum power switches. A key feature of the converter is its ability to provide bidirectional buck–boost operation in both power flow directions, while maintaining a reduced component count and improved efficiency through synchronous rectification. The converter’s performance is thoroughly analyzed under both continuous conduction mode (CCM) and discontinuous conduction mode (DCM). Furthermore, detailed small-signal modeling and closed-loop controller design are developed for both voltage-mode and current-mode control. A 200 W experimental prototype employing SiC MOSFETs is implemented to validate the theoretical analysis. Experimental results confirm the high efficiency, robust dynamic response, and practical feasibility of the proposed converter for next-generation power conversion applications. © 2013 IEEE.Item A Nonisolated High Gain Bidirectional DC–DC Converter With Reduced Switch Count: Analysis and Implementation(Institute of Electrical and Electronics Engineers Inc., 2025) VSheeja, S.; Kalpana, R.; Singh, B.This article investigates a bidirectional dc–dc converter having a very high voltage gain for grid integration of a microgrid supported by renewable power sources. The proposed converter interfaces the low-voltage solar PV and battery energy storage systems with a high-voltage system. Because of its large voltage gain both in forward and reverse operating modes, the proposed converter can be used at lower and moderate duty ratios. In comparison to previously reported topologies of a similar nature, this converter can provide better performance with fewer switches and passive components, resulting in better efficiency. The input current's ripple is observed to be lowered as a result of the parallel operation of inductors. The converter stability is investigated using state space modeling and small signal analysis. The laboratory hardware prototype confirms the suggested converter's effectiveness for bidirectional operation, and the outcomes are in line with theoretical studies. © 2020 IEEE.Item High-Gain Nonisolated DC–DC Converter with Zero Input Current Ripple for Fuel Cell Electric Vehicles(Institute of Electrical and Electronics Engineers Inc., 2025) Shetty, S.; Mishra, S.; Vinatha Urundady, U.This paper presents a novel single-switch, common-ground high-gain DC–DC converter for vehicular applications, integrating a Current Mirror Ripple Cancellation Circuit (CMRCC) to achieve a continuous input current with negligible ripple. The proposed power stage incorporates one switched inductor–capacitor (SLC) cell and one switched capacitor (SC) cell, along with a clamping circuit to reduce voltage stress on the switching device, thereby enhancing efficiency and reliability. This configuration delivers high voltage gain while maintaining control simplicity through a single-switch design and minimizing electromagnetic interference via the common-ground structure. A comprehensive theoretical analysis is provided, covering voltage gain, efficiency, component stress, and open-loop stability. A 48 V/400 V, 350 W laboratory prototype was developed to validate the proposed design under dynamic load and source variations, achieving a peak efficiency of 94.4%, an input current ripple below 1%, and a transient deviation of less than 10% under 30% load and 20% source step changes. These results confirm that the proposed integrated approach offers a compact, high-performance, and application-ready solution for electric vehicle powertrains and renewable energy systems. © 2015 IEEE.