Faculty Publications
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Publications by NITK Faculty
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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 Power Quality Enhanced Push-Pull Converter-Based Two-Stage Onboard Charger for Electric Vehicle Applications(Institute of Electrical and Electronics Engineers Inc., 2025) Suprabha Padiyar, U.S.; Kalpana, R.This paper presents an efficient two-stage onboard charger (OBC) using AC-DC converters with improved power quality for electric vehicle (EV) applications. The first stage comprises a diode bridge rectifier (DBR) without an input AC filter and a front-end boost converter (FBC) as a power factor correction (PFC) circuit, stabilizing the output voltage for efficient power transfer. The boost inductor current control is facilitated using a phase-locked loop to achieve input current wave shaping. This FBC drives the second-stage back-end push-pull converter (BPPC) operating in buck mode to ensure the battery is charging in constant current (CC) control mode. The push-pull converter demands its inductor current to be continuous due to the CC mode of battery charging. A detailed analysis of the power converters is conducted through simulations performed using the MathWorks SIMULINK software. Furthermore, a scaled-down hardware prototype has been developed, utilizing a dSPACE 1202 controller, to evaluate the effectiveness of the charger for a 48 V, 100 Ah battery. The test results demonstrate satisfactory performance and compliance with the IEC 61000-3-2 standard. This design effectively maintains input AC power quality during battery charging, highlighting its potential for enhancing EV charging infrastructure. © 2025 The Authors.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.