Browsing by Author "Reddivari, R."

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A Comparative Study of Different Capacitor Voltage Control Design Strategies for Z-Source Inverter
(Taylor and Francis Ltd., 2022) Kumar, K.V.; Reddivari, R.; Jena, D.
The Z-source inverter (ZSI) is a prominent single-stage power conversion topology compared to traditional voltage source inverter (VSI)/ current source inverter (CSI). It adds the additional buck–boost capability to input voltage with improved reliability. However, the non-minimum phase (NMP) behavior is the major disadvantage of ZSI due to the existence of the right half plane (RHP) zero in the converter transfer functions. The existences of RHP zero destabilize the wideband feedback loops, which imply high gain instability and introduce the constraints on controller design. This paper presents different types of controllers and its design to maintain the required capacitor voltage with better transient response for non-minimum phase ZSI. Different tuning algorithms have been considered for both proportional–integral (PI), and integral–proportional (IP) control schemes. Also, the unified control algorithm has been implemented with both simple boost pulse width modulation (SBPWM) and a modified space vector pulse width modulation (MSVPWM) schemes to obtain the required capacitor voltage. The converter performance is comprehensively analyzed for different controllers and observations are tabulated. The complete analysis has been carried out using the MATLAB/Simulink environment for the proposed models. © 2022 IETE.
A Correlative Investigation of Impedance Source Networks: A Comprehensive Review
(Taylor and Francis Ltd., 2022) Reddivari, R.; Jena, D.
In recent times, impedance networks have been developed to overcome the limitations and problems of traditional VSI / CSI and various traditional dc-dc converter networks. From then on, impedance source converters replace the entire range of power electronic converters: dc-dc (converters), dc-ac (inverters), ac-dc (rectifiers), ac-ac frequency regulators (matrix converters). In addition, the impedance source networks are used in a wide range of applications like PV-Grid tied systems, wind energy systems, distributed generations, adjustable speed drives, UPS systems, battery/supercapacitor/flywheel energy storage systems, electric vehicles, electronic loads, and dc circuit breakers, etc. Several topological changes have occurred to improve the performance of conventional ZSIs. This paper provides a concise review of the state-of-the-art impedance source topologies. This paper categorized the impedance topologies based on their functionality, performance improvements, and switching configuration employed. This paper also demonstrates the fundamental structural similarities, advantages, and disadvantages of each topology, which helps the end-users in topology selection. Â© 2022 IETE.
A Correlative Investigation of Impedance Source Networks: A Comprehensive Review
(Taylor and Francis Ltd., 2022) Reddivari, R.; Jena, D.
In recent times, impedance networks have been developed to overcome the limitations and problems of traditional VSI / CSI and various traditional dc-dc converter networks. From then on, impedance source converters replace the entire range of power electronic converters: dc-dc (converters), dc-ac (inverters), ac-dc (rectifiers), ac-ac frequency regulators (matrix converters). In addition, the impedance source networks are used in a wide range of applications like PV-Grid tied systems, wind energy systems, distributed generations, adjustable speed drives, UPS systems, battery/supercapacitor/flywheel energy storage systems, electric vehicles, electronic loads, and dc circuit breakers, etc. Several topological changes have occurred to improve the performance of conventional ZSIs. This paper provides a concise review of the state-of-the-art impedance source topologies. This paper categorized the impedance topologies based on their functionality, performance improvements, and switching configuration employed. This paper also demonstrates the fundamental structural similarities, advantages, and disadvantages of each topology, which helps the end-users in topology selection. © 2022 IETE.
A cost-effective single-phase semi flipped gamma type magnetically coupled impedance source inverters
(John Wiley and Sons Ltd, 2021) Gautham, T.N.; Reddivari, R.; Jena, D.
This paper presents a new two winding coupled inductor architecture for a semi magnetically coupled impedance source (SMCIS) inverter by connecting the coupled inductor windings in flipped gamma fashion. The proposed topology is derived from the conventional MCIS inverters. It can produce sinusoidal output voltage/current without using any shoot-through operation and output LC filter, which improves the system reliability. Further, a doubly grounded feature, no start-up inrush current, reduced component count, low input current ripple, continuous output currents, and small leakage currents are the major advantages of the proposed inverter. However, the proposed semi flipped gamma MCIS inverters still suffer from limited output voltage gain problem. The voltage-boosting feature is added to the proposed inverter by connecting two converter modules in differential boost configuration through the embedded structure. The voltage-boosting ability is the major advantage of this differential boost embedded configuration. It has flexibility in choosing a wide range of duty cycle operation from zero to one (whereas, the duty cycle was limited to 0.666 in case of semi-Z-source inverter [ZSI]). The modes of operation, design procedure, and feature comparisons of proposed inverters are discussed in this paper. Finally, the effectiveness of proposed inverters is validated through simulation and experimental results in terms of component count, voltage gain, and feature comparison. © 2020 John Wiley & Sons, Ltd.
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.
A detailed model of Z-source converter considering parasitic parameters
(Institute of Electrical and Electronics Engineers Inc., 2018) Reddivari, R.; Jena, D.
This paper contributes towards the small-signal analysis of Z-Source converter considering all the losses introduced by non-ideal inductors, capacitor and semiconductor switches. The mathematical model is formulated using state-space averaging method under continuous conduction mode (CCM). The system dynamics are analyzed through computer simulation and reported using frequency response plots and pole-zero plots. The optimum values of the ZSC parameters i.e. the value of inductors and capacitors under CCM operating condition are determined. The effects of equivalent series resistance values (ESR) on the efficiency and boost capability of ZSC are analyzed mathematically, validated with MATLAB/SIMULINK and also with help laboratory proto-type model. Â© 2018 IEEE.
A low voltage harvesting in photovoltaic generation systems using negative embedded Z-source inverter
(John Wiley and Sons Ltd, 2021) Reddivari, R.; Jena, D.
Commercial two-stage grid-connected photovoltaic (PV) inverters suffer from a narrow band maximum power point (MPP) voltage operation. If the voltage falls outside this narrow band, the inverter switches its operation from MPP to power limitation mode. At the same time, these inverters need high start-up voltages to turn them ON again. The evolutionary algorithms are widely used to track the global MPP at wide input (PV) voltage range. However, the global MPP at low PV voltages cannot be boosted to grid voltage level due to the limited duty ratio of conventional DC-DC converters that restricts the inverter MPP voltage range. This paper summarizes the potential challenges of narrow range MPP voltage solar inverters under partial shading scenarios. Also, demonstrates a proposed single-stage negative embedded Z-source single-stage inverter (NEZSI) to extend the MPP voltage range. The proposed topology wakes up the inverter at lower threshold voltages that enables it to extract energy from low PV string voltages. In addition, the proposed inverter tracks the MPP at a faster rate with low input current ripple, inrush current, and device stresses. Further in this paper, qualitative and quantitative comparisons between state-of-the-art topologies are provided to highlight the superiority of the proposed inverter. Simulation and experimental validation of the proposed inverter are demonstrated with traditional perturb and observe (P&O) and variable step P&O algorithms. © 2021 John Wiley & Sons Ltd.
A Negative Embedded Differential Mode ?-Source Inverter with Reduced Switching Spikes
(Institute of Electrical and Electronics Engineers Inc., 2020) Reddivari, R.; Jena, D.
Magnetically coupled impedance source networks (MCIS) are capable of producing higher voltage gains at the expense of high switching voltage spikes due to the presence of leakage inductance. These voltage spikes decorate the converter efficiency and life expectancy of switches. Therefore, to reduce the voltage spikes, a negative embedded differential mode gamma source inverter (NEDM ${{\Gamma }}$ ZSI) is presented in this brief. The proposed inverter can achieve higher voltage gains with reduced switching voltage spikes and low capacitor voltage stresses compared to other MCIS networks. Also, the proposed inverter draws continuous input current from the dc mains, having a common ground, and uses the minimum number of component in a circuit. The operating principle of the proposed NEDM ${{\Gamma }}$ ZSI is analyzed in electrical and magnetic domains. The ability of the proposed impedance network, in terms of voltage spike suppression has been verified experimentally using DC-DC converter configuration. Finally, the performance of a NEDM ${{\Gamma }}$ ZSI is validated with simulation and experimental verification using a single-phase inverter configuration. © 2004-2012 IEEE.
Analysis of RCD snubber based non-ideal Z-source inverter using average modelling approaches
(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2020) Reddivari, R.; Jena, D.
Z-Source inverters (ZSIs) are one of the most promising single-stage power converters in modern industrial applications. However, these ZSIs exhibit non-minimum phase behaviour as a result of right half-plane (RHP) zero in the converter transfer functions and impose a constraint on the controller design. A detailed mathematical model of the converter plays a crucial role in the design of an efficient control strategy. This paper presents a detailed mathematical model of non-ideal ZSI using averaged modelling approaches and its comparisons are summarised. The pole-zero and step response plots reveals the impact of parasitic elements and parameter variations on system steady-state and dynamic performance. Finally, the effects are outlined, which gives a basic guideline to the designers in the converter performance optimisation such as the feedback control bandwidth, damping factor, resonant frequency, and overshoot/undershoot in the desired output. The sensitivity function is defined for a voltage gain of ZSI with respect to system parasitic elements and snubber parameters. In order to validate the theoretical analysis of converter dynamics, a laboratory prototype model of 50 watts ZSI is developed. Further, a hardware implimentation of PID-based capacitor voltage control is shown to check the effectiveness of the derived transfer functions on closed-loop performance. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.
Analysis, Design, and Performance Evaluation of Differential-Mode Y-Source Converters for Voltage Spikes Mitigation
(Institute of Electrical and Electronics Engineers Inc., 2020) Reddivari, R.; Jena, D.; Gautham, G.
Impedance source converters (ISC) based on the magnetic coupling can enhance their voltage gains by maintaining lower shoot-through duty ratios and reduced passive component count. However, the nonzero leakage inductance in the practical ISC generates high switching voltage spikes resulting in poor voltage regulation. Therefore, an absorbing circuit with additional components is crucial to reduce these voltage spikes and to absorb the energy stored in leakage inductances. This article presents a family of differential-mode Y-source converters (DMYSCs) as an alternative to the latest Y-source converter that mitigates the switching voltage spikes without increasing the number of components. The proposed converters DMYSC-I, DMYSC-II, and improved ?-type Y-source converter are derived from the original Y-source impedance network by altering the winding orientation. In this article, the respective topologies with their working principles are studied and the characteristics are compared with other Y-source converters. Simulation and experimental results have confirmed the abilities of the proposed converters to mitigate their switching voltage spikes. © 1972-2012 IEEE.
Anionic Fluorine and Cationic Niobium Codoped Tin Oxide Thin Films as Transparent Conducting Electrodes for Optoelectronic Applications
(John Wiley and Sons Inc, 2023) Reddivari, R.; Reddy, N.P.; Santhosh, R.; Maharana, G.; Fernandes, J.M.; Padmanaban, D.B.; Kovendhan, M.; Veerappan, G.; Laxminarayana, G.; Murali, M.; Joseph, D.P.
Exploration of alternatives for supplementing indium tin oxide electrode is currently trending due to scarcity of indium, leading to a steep increase in the cost of related optoelectronic components. Codoping of niobium (Nb) and fluorine (F) into SnO2 lattice as cationic and anionic dopants, respectively, is explored by spray deposition technique. A fixed 10 wt% F and varying Nb concentration from 0 to 5 wt% is incorporated into the SnO2 lattice. X-ray diffraction reveals substitution of Nb and F into the SnO2 lattice without altering the structure. Optical transmittance is found to increase with Nb content up to 4% of Nb (77.59%), and it decreases thereafter. Scanning electron microscope and optical profiler imply a relatively smooth surface with sharp-tipped particles which vary with Nb concentration. Sheet resistance decreases up to 3 wt% of Nb doping and increases thereafter. Contact angle measurement indicates that upon doping with Nb, the films turn hydrophilic. Among the deposited films, 4 wt% of Nb-doped film shows the highest figure of merit of 5.01 × 10−3 Ω−1. The surface work function of the 4 wt% Nb-doped SnO2 film is 4,687.85 meV. The optimal films are tested as electrodes in dye-sensitized solar cells and are discussed in detail. © 2023 Wiley-VCH GmbH.
Comparative Overview of Internal Model Control Based PID, State Feedback Integral, and Sliding Mode Controllers for Buck Converter
(Institute of Electrical and Electronics Engineers Inc., 2019) Shankar, K.G.; Jena, D.; Reddivari, R.
The controller plays a key role in the performance of switched mode power supplies (SMPS). Various control techniques have been proposed in the literature to improve the performance of SMPS. However, each and every controller has its own merits as well as demerits. This paper used three different kinds of control schemes such as IMC-PID control, state feedback integral control, and sliding mode control, applied to the traditional buck converter to show their effectiveness. Firstly, a detailed small-signal model of a buck converter is developed. The small signal transfer function derived from the small signal model is used to calculate the control parameters. The working principle and control parameter tuning of above-mentioned control schemes are clearly shown with mathematical expressions. Finally, the effectiveness of the given controllers is validated by using MATLAB/SIMULINK software platform. Â© 2019 IEEE.
Component level reliability evaluation of boost converter, Z-Source, and improved gamma type ysource inverters
(Institute of Electrical and Electronics Engineers Inc., 2020) Kumbale, S.; Pius, J.; Reddivari, R.; Jena, D.
A power electronic converter should support high efficiency and high reliability to improve renewable energy connected to grid applications. Notably, low power photovoltaic (PV) applications use module-level DC-DC and DC-AC converters, where the minimum and maximum operating voltage ranges of the power conversion system is decided by DC-DC converter topology. These DC-DC converters highly suffer in the process of maximum power point tracking under extreme weather conditions and are installed with limited maintenance in remote locations. These cumulative factors make the power converters vulnerable and likely to fail early in the photovoltaic system, though the lifetime of the PV panels is about 25-30 years. To ensure longetivity, the power electronic converter must satisfy high efficiency and high-reliability demands even at extreme weather and loading conditions. Taking these constraints into account, this paper introduces a simple algorithm for understanding the component level reliability of power electronic converters under various input voltage, load, and ambient temperature conditions. The suggested algorithm can be modified depending on the topology of the converter The process involves defining critical components, assessing failure prognosis, and establishing a criterion to estimate failure time. The reliability evaluation of a conventional boost converter, Z-source inverter, and improved gamma type-YSI is presented in this paper as examples of the proposed algorithm. The electro-thermal circuit simulation in PLECS is used to validate the effectiveness of the proposed reliability algorithm. Â© 2020 IEEE.
Defect-mediated time-efficient photocatalytic degradation of methylene blue and ciprofloxacin using tungsten-incorporated ternary perovskite BaSnO3 nanoparticles
(Elsevier Ltd, 2024) Jayavelu, Y.; Maharana, G.; Rajender, G.; Reddivari, R.; Divyadharshini, S.; Baby, B.H.; Kovendhan, M.; Fernandes, J.M.; Joseph, D.P.
Photocatalytic water purification has been extensively explored for its economic, eco-friendly, and sustainable aspects. In this study, tungsten (W) incorporated BaSn1-xWxO3 (x = 0 to 0.05) nanoparticles synthesized by facile hydrogen peroxide precipitation route has been demonstrated for photocatalytic degradation of methylene blue (MB) dye and ciprofloxacin (CIP) antibiotic. The structural analysis indicates the presence of hybrid composite-like nanostructures with reduced crystallinity. Optical studies reveal blueshift in bandgap and decrease in oxygen vacancy defects upon W-incorporation. Pure BaSnO3 shows overall enhanced photocatalytic activity towards MB (90.22%) and CIP (78.12%) after 240 min of white LED light and sunlight irradiation respectively. The 2 % W-incorporated BaSnO3 shows superior photocatalytic degradation of MB (26.89%) and CIP (45.14%) within first 30 min of irradiation confirming the presence of W to be beneficial in the process. The free radical study revealed the dominant role of reactive hole (h+) and oxygen radical (O2•−) species during photodegradation and their intermediates are investigated to elucidate the degradation mechanism of MB within 30 min of irradiation. This study is promising towards developing defect mediated and time-efficient photocatalysts for environmental remediation. © 2024 Elsevier Ltd
Design Implementation of High Boost Embedded Semi Quasi-ZSI for Photovoltaic System Applications
(Institute of Electrical and Electronics Engineers Inc., 2019) Gautham, T.N.; Reddivari, R.; Jena, D.
The semi Z-source inverter (SZSI) is a well suitable non-isolated converter for grid-connected PV systems, because of its low cost and doubly grounded features. In addition, an SZSI produces a sinusoidal output voltage without using any additional low pass filter circuit. However, the limited output voltage range, the operating region of the duty cycle is restricted to 0.666, discontinuous input currents are the main concerns of SZSI. In order to overcome the above limitations, an embedded semi quasi Z-source inverter (ESqZSI) topology is proposed, that is constructed with two semi quasi ZSIs. Further, a quasi Z-source converter (qZSC) is interfaced as front-end DC-DC converter to implement Perturb and Observe (P and O) MPPT method. The symmetrical and asymmetrical output voltage control methods are presented to improve the voltage profile. The component design specifications and its sizing are clearly discussed for qZSC and ESqZSI. Comparing with H-bridge inverter, the proposed EZSI topology has lower converter ratings, low stress on the system and reduced leakage currents. Finally, the performance of the proposed system is verified through MATLAB/SIMULINK. Â© 2019 IEEE.
A detailed model of Z-source converter considering parasitic parameters
(2018) Reddivari, R.; Jena, D.
This paper contributes towards the small-signal analysis of Z-Source converter considering all the losses introduced by non-ideal inductors, capacitor and semiconductor switches. The mathematical model is formulated using state-space averaging method under continuous conduction mode (CCM). The system dynamics are analyzed through computer simulation and reported using frequency response plots and pole-zero plots. The optimum values of the ZSC parameters i.e. the value of inductors and capacitors under CCM operating condition are determined. The effects of equivalent series resistance values (ESR) on the efficiency and boost capability of ZSC are analyzed mathematically, validated with MATLAB/SIMULINK and also with help laboratory proto-type model. � 2018 IEEE.
Differential mode gamma source inverter with reduced switching stresses
(2018) Reddivari, R.; Jena, D.
Impedance source inverters are covered with entire spectrum of power conversion process (dc-dc, dc-ac, ac-dc, and ac-ac). The traditional impedance source inverter suffers from high switching stresses and poor efficiency during high boost requirements. Compared to traditional impedance source inverters, the transformer based impedance source inverters are able to boost the output voltage gain and modulation index simultaneously with reduced passive components. The applications of transformer based gamma source impedance inverters are limited due to the difficulty in maintaining tight coupling, high instantaneous currents, increasing turn's ratio, high cost and large size. However, the gamma source inverter increases voltage gain by reducing turns ratio. This paper presents the operational modes of gamma source inverter in electric and magnetic domains, which helps the researchers to understand effects of transformer coupling in converter performance. In addition, the differential mode gamma source inverter is proposed that reduces the switching stresses. The operating principles of the proposed converter have been analyzed mathematically. Finally the theoretical analysis of proposed impedance inverter is validated by using MATLAB/SIMULINK. � 2017 IEEE.
Differential mode gamma source inverter with reduced switching stresses
(IEEE Computer Society, 2017) Reddivari, R.; Jena, D.
Impedance source inverters are covered with entire spectrum of power conversion process (dc-dc, dc-ac, ac-dc, and ac-ac). The traditional impedance source inverter suffers from high switching stresses and poor efficiency during high boost requirements. Compared to traditional impedance source inverters, the transformer based impedance source inverters are able to boost the output voltage gain and modulation index simultaneously with reduced passive components. The applications of transformer based gamma source impedance inverters are limited due to the difficulty in maintaining tight coupling, high instantaneous currents, increasing turn's ratio, high cost and large size. However, the gamma source inverter increases voltage gain by reducing turns ratio. This paper presents the operational modes of gamma source inverter in electric and magnetic domains, which helps the researchers to understand effects of transformer coupling in converter performance. In addition, the differential mode gamma source inverter is proposed that reduces the switching stresses. The operating principles of the proposed converter have been analyzed mathematically. Finally the theoretical analysis of proposed impedance inverter is validated by using MATLAB/SIMULINK. Â© 2017 IEEE.
Differential Mode Y-Source DC-DC Converter for Better Performance with Loosely Coupled Inductors
(2018) Reddivari, R.; Jena, D.; Goutham, T.N.
Magnetically coupled inductor based impedance source dc-dc boost converters are capable of producing high voltage boost with reduced components and low shoot-through duty ratios (STDR). A Y-source converter (YSC) is one of the prominent topologies in the family of magnetically coupled impedance networks, which offers the highest degree (three degrees) of freedom to the controller to maintain constant output voltage compared to the former magnetically coupled Z-source topologies. However, YSC requires tight coupling (nearly unity) among three coupled windings to generate high voltage boosting. But, the continuation of tight coupling is quite difficult in the design of offline YSC when it involves high switching frequency operations. The leakage inductances are common in the design of any magnetically coupled topologies under high operational frequencies. High voltage overshoots, voltage boost degradations are the consequences of the leakage inductance with loosely coupled inductors. This paper attempts to analyse the effect of leakage inductances mathematically with detailed circuit representation of coupled inductors. In addition, a differential mode Y-source converter (DYSC) is proposed which is derived from the former Y-source network by changing the winding orientation. The performance of the proposed DYSC is analyzed using Matlab/SimulationsTM and also compared with YSC. The hardware results are presented to validate the theoretical simulations of both YSC and DYSC topologies. � 2018 IEEE.
Differential Mode Y-Source DC-DC Converter for Better Performance with Loosely Coupled Inductors
(Institute of Electrical and Electronics Engineers Inc., 2018) Reddivari, R.; Jena, D.; Goutham, T.N.
Magnetically coupled inductor based impedance source dc-dc boost converters are capable of producing high voltage boost with reduced components and low shoot-through duty ratios (STDR). A Y-source converter (YSC) is one of the prominent topologies in the family of magnetically coupled impedance networks, which offers the highest degree (three degrees) of freedom to the controller to maintain constant output voltage compared to the former magnetically coupled Z-source topologies. However, YSC requires tight coupling (nearly unity) among three coupled windings to generate high voltage boosting. But, the continuation of tight coupling is quite difficult in the design of offline YSC when it involves high switching frequency operations. The leakage inductances are common in the design of any magnetically coupled topologies under high operational frequencies. High voltage overshoots, voltage boost degradations are the consequences of the leakage inductance with loosely coupled inductors. This paper attempts to analyse the effect of leakage inductances mathematically with detailed circuit representation of coupled inductors. In addition, a differential mode Y-source converter (DYSC) is proposed which is derived from the former Y-source network by changing the winding orientation. The performance of the proposed DYSC is analyzed using Matlab/SimulationsTM and also compared with YSC. The hardware results are presented to validate the theoretical simulations of both YSC and DYSC topologies. Â© 2018 IEEE.