Faculty Publications

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Publications by NITK Faculty

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Subject: search.filters.subject.Fixed frequency

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    A Fixed-Frequency ZVS Integrated Boost Dual Three-Phase Bridge DC-DC LCL-Type Series Resonant Converter
    (Institute of Electrical and Electronics Engineers Inc., 2018) Nagendrappa, H.; Bhat, A.K.S.
    A new fixed-frequency controlled three-phase dc-dc LCL-type series resonant converter with integrated boost function is proposed for medium to large power applications with wide input voltage variation that is typical of alternate energy sources. The converter includes a dual three-phase LCL-type resonant bridge inverter modules connected in parallel, thus significantly reducing the component stresses when subjected to medium to large power applications. The fixed-frequency control of the output power is achieved by phase shifting the gating signals of one module with respect to the other, while the rectified voltage at the secondary windings of a three-phase high-frequency transformer connected between the two modules is added to the input voltage to boost the supply voltage to the modules. The zero-voltage-switching of all the switches is accomplished by designing the converter to operate in the lagging PF mode for wide variations in the input voltage and the load. Detailed modeling of the three-phase boost section is done and the steady-state analysis of the proposed converter for three-phase LCL-type dc-dc converter modules using complex ac circuit analysis method is presented. For illustration purpose, a dc-dc converter of 600 W is designed, and its performance is verified using PSIM simulations. An experimental model of the converter is built in the laboratory to verify its performance for wide variations in input voltage and load changes. © 2017 IEEE.
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    A 10 kW ZVS integrated boost dual three-phase bridge DC–DC resonant converter for a linear generator-based wave-energy system: Design and simulation
    (MDPI AG indexing@mdpi.com, 2019) Nagendrappa, N.; Bhat, A.K.S.
    The design and performance analysis of a 10 kW three-phase DC–DC LCL-type resonant converter having a built-in boost function were carried out. This high-power converter is proposed for its application in grid-interfacing a linear generator (LG)-based wave-energy system. Fixed-frequency control is used, and the converter was designed to operate with a lagging power factor. It is shown that all switches turn on with zero-voltage switching (ZVS) for wide input voltage and load variations. This results in reduced switching losses and stresses, which is very important in large-power applications. The performance of the converter was studied through PSIM simulation software. Theoretical and simulation results are presented for comparison. Power-loss break-down analysis of the designed converter was carried out and the summary of results is presented. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.
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    Resonant DC/DC Converters: Investigating Phase-Shift Control
    (Multidisciplinary Digital Publishing Institute (MDPI), 2023) Reddy, V.B.; Mahajan, M.S.; Subramaniam, U.
    The paper presents an innovative approach to control the voltage of an LCL-T type converter at the output side against variation at input and load ports, utilizing a fixed-frequency phase-shift control scheme. The examination of the converter is performed employing a Fourier series method that takes into account the effect of n-harmonics. To assure high-frequency switches with a zero-voltage switching (ZVS) technique, the lagging pf mode is utilized. PSIM simulations were used to investigate the performance of a 300 W converter. With the minimal input voltage, all switches turn on with ZVS for all loading conditions, whereas the ZVS strategy loses by two switches when the voltage at the input is highest. The power loss calculations of each component are performed and presented in a pie chart. The findings of the experiments are presented and verified with theoretical and simulation results. It is demonstrated that for both input voltage and load fluctuations, a minor adjustment in pulse width is sufficient to keep the output voltage constant. © 2023 by the authors.
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    Fixed-frequency modified gating signals controlled high-frequency isolated LCL-T DC-DC resonant power converter
    (Taylor and Francis Ltd., 2025) Reddy, V.B.; Ur Rehman, M.B.; Srinivas, B.; Nagendrappa, N.
    In this paper, a fixed-frequency modified gating signals controlled LCL-T type of resonant power converter is proposed. The converter is designed to operate in lagging power factor (pf) mode to ensure zero-voltage switching (ZVS) of the inverter switches. Steady-state analysis of the converter is carried out using the Fourier series approach by considering the effect of n-harmonics. A 300 W converter is designed, and its performance is studied using PSIM simulations. It is shown that all inverter switches turn-on with ZVS for entire loading conditions with the minimum input voltage, while only one switch loses ZVS when the input voltage is maximum. Also, a small change in pulse width is enough to regulate the output voltage for wide variations in the input voltage and the load. Power loss breakdown analysis is performed. The experimental prototype of the LCL-T resonant converter is built and tested to validate the theoretical and simulation results. The results have been compared and discussed. © 2024 Informa UK Limited, trading as Taylor & Francis Group.