Faculty Publications
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Publications by NITK Faculty
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Item A critical analysis of Z-source converters considering the effects of internal resistances(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2018) Reddivari, R.; Jena, D.Nowadays Z-source networks are the most promising power converter networks that cover almost all electric power conversion (dc–dc, dc–ac, ac–dc and ac–ac) applications. However, the controller design is critical for Z-source converter (ZSC) due to the presence right-half-plane zero (RHPZ) in the control-to-capacitor-voltage transfer function. This RHPZ exhibits non-minimum phase undershoot in the capacitor voltage and also in the dc-link voltage waveforms. A perfect small-signal model is required to predict locations of the RHP zero and its dynamics. This paper contributes towards the small-signal analysis of ZSC under continuous conduction mode considering the parasitic resistance of the inductor, equivalent series resistance of the capacitor, internal resistances of active switch and forward voltage drop of the diode. The maximum allowable value of shoot-through duty ratio (STDR) and voltage gain for different values of the internal resistance and load resistance are discussed in this paper. The accuracy of the developed small-signal average model is compared with detailed circuit model in MATLAB/SIMULINK. Finally, the steady-state simulation results of ZSC are validated with hardware results. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.Item Non-Isolated Power Factor Corrected AC/DC Converter with High Step-Down Voltage Ratio for Low-Power Applications(Hindawi Limited, 2022) Annambhotla, L.T.S.; Parthiban, P.This paper proposes a high step-down ratio AC-DC converter employing a quadratic buck converter with power factor correction. Conventional active power factor correction topologies employ boost-based correction schemes for unity power factor operation. This will require a steeper step-down ratio and higher switch voltage stress apart from complexity in the control scheme with sensors. The structure of the proposed topology is developed by combining the power factor correction stage with a high step-down stage. The passive input filter is split up into two for the purpose of reducing the thermal heating apart from offering a higher power factor. A single switch operation reduces the complexity of the control scheme. In addition, the number of conducting devices during the current path is also the same as the conventional buck converter due to cascading and hence offers lower conduction losses. The need for the converter to operate at an extremely low duty cycle is reduced due to the quadratic stage structure. The proposed converter operates at a moderate duty cycle, offering higher step-down voltage apart from reducing filtering requirements. MATLAB R2020b is used for carrying out simulation studies. Xilinx FPGA-based controller using system generator is implemented for the generation of pulses of appropriate duty cycle. Simulation and experimental results for a 150 W prototype are presented. An investigation and comparative evaluation of the conventional bridgeless buck system with the quadratic buck converter are carried out. The proposed structure offers the benefit of a higher step-down voltage ratio incorporating an inherent power factor correction stage along with the AC/DC stage. © 2022 Lalitha T. S. Annambhotla and P. Parthiban.Item 1 V, 20 nW True RMS to DC Converter based on Third Order Dynamic Translinear Loop(Taylor and Francis Ltd., 2023) Mansoor, C.B.; Patii, A.; Rekha, S.This paper presents a novel current-mode true RMS–DC converter based on the dynamic translinear principle. The converter is designed using a third-order translinear loop, resulting in a very compact and simple circuit. The proposed circuit is designed in 65 nm CMOS technology, operates with 1 V power supply, has only 14 transistors and performs satisfactorily over a wide input current range of 300 nA–950 nA and for a frequency range of 600 Hz–650 kHz for a capacitance value of 10 nF. The frequency range of operation can be tuned by varying the external off chip capacitor and the bias current. The circuit consumes 20 nW static power, 1.6 μW maximum dynamic power and offers the lowest FOM among the other RMS–DC converter circuits presented in the literature. Comprehensive mathematical analysis along with the post layout simulation results confirm the validity of the proposed circuit. To test the use of converter in real world scenarios, the proposed converter is introduced within a typical ECG detection system and the results show that the circuit is an attractive solution for RMS–DC conversion in low-voltage low-power applications. © 2023 IETE.Item A Three-Phase Isolated Multilevel AC-DC Converter for Dual Electric Vehicle Battery Charging(Institute of Electrical and Electronics Engineers Inc., 2025) Vinusha, B.; Kalpana, R.; Kishan, D.In this paper, a two-stage electric vehicle (EV) architecture of an AC-DC converter is proposed for charging two batteries at a time. It consists of a three-phase multilevel boost PFC converter followed by a bidirectional dual-output DC-DC converter. Also, the DC-DC converter has a Zero voltage switching (ZVS) and isolated outputs. The two stages function independently, allowing the AC-DC stage to operate in continuous conduction mode (CCM) without affecting the duty cycle variation of the DC-DC stage. A suitable control technique is also proposed to improve total harmonic distortion (THD) and power factor, equal power sharing of two batteries. A detailed operating analysis of the proposed dual battery charger is discussed. The effectiveness of the proposed charger is validated by extensive test of laboratory prototype. © 1972-2012 IEEE.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 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.Item A Novel Dual-Input Single-Output High-Gain DC-DC Converter for Interfacing Fuel Cell with High-Way Charging Station Applications(Institute of Electrical and Electronics Engineers Inc., 2025) Diwakar Naik, M.D.; Vinatha Urundady, U.This article presents a novel dual-input single-output high-gain dc-dc converter designed specifically for interfacing fuel cells (FCs) with high-way charging station applications. The converter boasts several notable features, including high output voltage gain achieved with only two switches, continuous input current, reduced switch stress, and the ability to provide a reliable continuous power supply. This article elucidates the two operating modes of the converter along with their corresponding switching states. In addition, it delves into the design and analysis of the proposed converter, covering various aspects, such as the development of a state-space model and the derivation of the small-signal transfer function to comprehend the dynamic behavior of the converter. Moreover, a suitable control strategy using the k-factor method has been devised to effectively regulate the output voltage and ensure stability, even in the face of input voltage fluctuations. To validate the effectiveness of both the proposed converter and controller, a 150-W prototype was meticulously constructed and experimentally verified in a laboratory setting. © 2024 IEEE.