Faculty Publications
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Publications by NITK Faculty
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Item Automatic method for contrast enhancement of natural color images(Korean Institute of Electrical Engineers, 2015) Shyam, L.; Narasimhadhan, A.V.The contrast enhancement is great challenge in the image processing when images are suffering from poor contrast problem. Therefore, in order to overcome this problem an automatic method is proposed for contrast enhancement of natural color images. The proposed method consist of two stages: in first stage lightness component in YIQ color space is normalized by sigmoid function after the adaptive histogram equalization is applied on Y component and in second stage automatic color contrast enhancement algorithm is applied on output of the first stage. The proposed algorithm is tested on different NASA color images, hyperspectral color images and other types of natural color images. The performance of proposed algorithm is evaluated and compared with the other existing contrast enhancement algorithms in terms of colorfulness metric and color enhancement factor. The higher values of colorfulness metric and color enhancement factor imply that the visual quality of the enhanced image is good. Simulation results demonstrate that proposed algorithm provides higher values of colorfulness metric and color enhancement factor as compared to other existing contrast enhancement algorithms. The proposed algorithm also provides better visual enhancement results as compared with the other existing contrast enhancement algorithms. © The Korean Institute of Electrical Engineers.Item A novel nine-level boost inverter with a low component count for electric vehicle applications(John Wiley and Sons Ltd, 2021) Shiva Naik, B.S.; Yellasiri, Y.; Aditya, K.; Nageswar Rao, B.N.In electric vehicles (EVs), considerable battery cells are cascaded in series for motor driving to improve the output voltage. The series combination of battery cells causes challenges like isolation of faulty cells, voltage unbalance, and slow charge equalization. Therefore, state-of-charge (SOC) and voltage equalization circuits are often used in industries to protect the battery cells. A nine-level inverter circuit with a double voltage boost is proposed to reduce the above issues based on the switch-capacitor (SC) principle. Unique features like self-balancing, voltage boosting are attained, which cannot be achieved through traditional inverters. The proposed topology can operate at a wide range of modulation indices ((Formula presented.)) to produce different voltage levels. The absence of a back-end H-bridge in the proposed circuit offers low voltage stress across the semiconductors. The operating principle, capacitor sizing, and modulation approach are presented. Further, experimental tests are conducted at different loading conditions to verify the performance of the proposed circuit. © 2021 John Wiley & Sons Ltd.Item A Two-Stage Module Based Cell-to-Cell Active Balancing Circuit for Series Connected Lithium-Ion Battery Packs(Institute of Electrical and Electronics Engineers Inc., 2023) Manjunath, K.; Kalpana, R.; Singh, B.; Kiran, R.This article addresses a two-stage module based cell-to-cell active equalization topology based on a modified buck-boost converter for series connected Lithium-ion battery packs. In the proposed topology, initially module based equalizing currents are controlled. Subsequently, cell-based equalizers are controlled in parallel within each battery module. The proposed topology significantly reduces the balancing time by transferring higher balancing current from a strong cell to the weakest cell in a module directly. With the proposed topology's modularized design, reduces voltage stress on long strings of switches, resulting in improved performance with fewer components. The operating principle, control strategy and design constraints are analyzed in detail. The MATLAB/Simulink platform is utilized to demonstrate the feasibility of the proposed technique for balancing the energy in series connected battery cells. To reduce the complexity of the control approach, the digital control is implemented using an FPGA control board. Further, a laboratory prototype is developed to show the feasibility and operability of the proposed topology. © 1986-2012 IEEE.Item A Modularized Two-Stage Active Cell Balancing Topology With Reduced Balancing Time for Series Connected Li-Ion Battery String(Institute of Electrical and Electronics Engineers Inc., 2025) Manjunath, K.; Kalpana, R.; Singh, B.This paper introduces a modularized two-stage active cell balancing topology utilizing an improved buck-boost converter for a series-connected lithium-ion battery string. The proposed topology adopts a modular structure where each module comprises three cells, two inductors, and four MOSFET switches. The voltage monitoring circuit controls the switches to ensure each cell has same voltage by transferring charge from a source cell to target cell. This approach enables module-to-module balancing through a module equalizer while simultaneously targeting two cells within a module through a cell equalizer. Using modularization technique in the proposed topology, the balancing time is reduced significantly compared to cell equalization circuit. Moreover, using a combination of cell and module balancing, the balancing time is reduced effectively compared with performing cell balancing only under dynamic charging/discharging conditions. This methodology substantially reduces cell equalization time and enhances system performance with minimal components. Proposed topology is verified theoretically and experimentally with a five-module battery string under static and dynamic conditions. © 1972-2012 IEEE.