Faculty Publications
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Item Improvement in Harmonic Reduction of a Zigzag Autoconnected Transformer Based 12-Pulse Diode Bridge Rectifier by Current Injection at DC Side(Institute of Electrical and Electronics Engineers Inc., 2017) Vidyasagar, V.; Kalpana, R.; Singh, B.; P, P.P.In this paper, to improve the harmonic reduction ability in the input line current of a 12-pulse diode bridge rectifier using zigzag autoconnected transformer with a dc side current injection technique is presented. Conventional 12-pulse rectifier does not meet the IEEE-519 standard and therefore current injection technique at dc side is used to shape the converter current to minimize the harmonic distortion in the input line current. The proposed converter configuration uses a zigzag autoconnected transformer with inherent ability to block zero-sequence components, which eliminates the requirement of a zero-sequence blocking transformer, and thereby reduces the overall rating of the converter. The current injection technique at dc side enables to alter the dc side currents, which further shapes the input line currents to near sinewave with total harmonic distortion of less than 1% and power factor close to unity. The proposed converter configuration is simulated and analyzed in MATLAB/Simulink. The effects of variation in the magnitude of injected current on the input line current harmonics in terms of power quality indices are analyzed. A prototype of the proposed converter configuration is developed, and experimental results are presented to validate the theoretical design, analysis, and simulation results. © 1972-2012 IEEE.Item A 20-Pulse Asymmetric Multiphase Staggering Autoconfigured Transformer for Power Quality Improvement(Institute of Electrical and Electronics Engineers Inc., 2018) P, P.; Kalpana, R.; Singh, B.; Bhuvaneswari, G.This letter presents a 20-pulse multiphase staggering autoconfigured transformer (MSAT) for power quality improvement in medium and high power applications. The proposed autoconfigured transformer is a combination of delta and zig-zag transformers. Contrary to the prior art multipulse autoconnected transformers, magnetic rating of the proposed configuration is only 40% of the load rating in addition to improved power quality indices. Moreover, the creation of a neutral point ascribed to inbuilt zig-zag windings supplements as one of the remarkable advantages of the proposed MSAT. Therefore, with this suggested configuration, the performance of zig-zag transformer is accomplished within the autoconfigured transformer. A detailed comparison of the proposed MSAT configuration with that of other multipulse autoconnected transformers in terms of magnetic rating and power quality indices are presented. Further, the feasibility and operability of the proposed MSAT are verified and validated through experimental tests on the laboratory prototype. The test results so obtained complies with the IEEE-519 and IEC 61000-3-2 standards on power quality requirements. © 2017 IEEE.Item Power Quality Enhancement Using Current Injection Technique in a Zigzag Configured Autotransformer-Based 12-Pulse Rectifier(Institute of Electrical and Electronics Engineers Inc., 2018) Kalpana, R.; Chethana, K.S.; P, P.; Singh, B.This paper proposes a DC-side circuit configuration that improves the harmonic suppression ability of a 12-pulse diode bridge rectifier (DBR) using a zigzag configured autotransformer. The DC-side circuit uses a single-phase DBR along with interphase transformer which generates the required circulating current thereby modifies the DC currents at the DBR output, in turn shapes the input line current near to a sine wave. The proposed single-phase DBR is connected in parallel with the load which enables to reuse the harmonic energy thus improving the energy conversion efficiency. The zigzag configured autotransformer used for 12-pulse DBR possesses the inbuilt ability to hinder the zero-sequence components, which expel the need of zero sequence blocking transformer. The proposed configuration is analyzed, simulated in MATLAB Simulink and the simulation results are presented, which confirm the reduction of total harmonic distortion (THD) in the input line current thereby improving the power quality under large load variations. Furthermore, the viability of the proposed configuration is verified by experimental results, which confirm the suitability of the proposed configuration in industrial applications. © 1972-2012 IEEE.Item Application of voltage multiplier in 12-pulse rectifier for sinusoidal input current(Institution of Engineering and Technology journals@theiet.org, 2018) P, P.; Kalpana, R.; Singh, B.; Bhuvaneswari, G.A DC current injection circuit of a trifurcated autotransformer (TAT)-based 12-pulse diode bridge rectifier (DBR) is proposed which can help reduction of harmonics in the AC mains. The circuit at the DC side employs a voltage multiplier (VM) circuits namely voltage doubler, voltage tripler and voltage quadrupler and an interphase transformer which provides the required circulating current. This induced circulating current shapes the input AC line current near to a sine wave. The output of VM circuits is connected across the load and thereby reuses the harmonic energy absorbed by the system. Thus, improves the energy conversion efficiency of the proposed system. The TAT-based 12-pulse DBR has the implicit ability to prevent the zero sequence components thus expels the necessity of zero sequence blocking transformer. The proposed configuration is analysed, simulated in MATLAB Simulink and the simulation results are presented, which confirms the improvement in power quality parameters in the input AC line current. Further, the viability of the proposed configuration is verified by experimental results which confirm the suitability of the proposed configuration in AC-DC applications. © 2018 Springer Verlag. All rights reserved.Item A novel nine-level inverter with reduced component count using common leg configuration(Springer Science and Business Media Deutschland GmbH, 2023) Nageswar Rao, B.; Yellasiri, Y.; Shiva Naik, B.S.; Aditya, K.This article proposes a nine-level (9 L) inverter with a common leg configuration employing transformers and a single dc source. The suggested inverter uses eight switches and two transformers to produce 9 L output voltage. The suggested circuit minimizes the switches and transformers compared with existing transformer-based multilevel inverters (TMLI). Therefore, the proposed circuit cost, volume and complexity are also reduced. Additionally, a thorough comparison with the various 9 L inverter circuits is conducted to ensure the benefits of the suggested TMLI. A basic logic gate-based pulse width modulation (PWM) is implemented for the suggested 9 L inverter. Simulation and hardware studies verifying the feasibility and proficiency of the suggested inverter are performed. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Item A new single-phase multilevel inverter with improved modulation technique(John Wiley and Sons Ltd, 2023) Nageswar Rao, B.; Yellasiri, Y.; Shiva Naik, B.; Aditya, K.; K Panda, A.This article proposes a seventeen-level (17L) inverter with a common leg configuration and an improved modulation technique. The proposed inverter uses only 10 switches, one toroidal core transformer, and one dc source. Therefore, the proposed design offers less control complexity with reduced cost and volume. Additionally, the suggested modulation technique improves the load voltage quality by minimizing the harmonic content. Simulation and laboratory studies are performed to confirm the proficiency of the suggested inverter with a new modulation technique. Further, a thorough comparison with recent transformer-based circuits is carried out to highlight the benefits of the proposed structure. © 2023 John Wiley & Sons Ltd.Item A modified T-type multilevel inverter for renewable energy applications(Elsevier Ltd, 2024) Nageswar Rao, B.; Yellasiri, Y.; Shiva Naik, B.S.; Aditya, K.; Panda, A.K.The primary challenge in integrating renewable resources into grids using multilevel inverters (MLI) is the need for many separate DC sources and switching device counts. Transformer-based multilevel inverters (TMIs) have emerged to address this issue, aiming to minimize system components and boost source voltage with a single DC source. This research article introduces a novel TMI topology that utilizes only a single DC source and incorporates ten switches to produce good-quality load voltage with high magnitude. The proposed TMI offers several structural advantages, including self-galvanic isolation, reduced switching devices and uniform voltage levels across all turn ratios. Additionally, the TMI operates a switching method called pulse width modulation, which provides the gating pulses to all the power semiconductor devices in the proposed TMI. An experimental model has been created in a laboratory environment, and simulations are performed using the MATLAB/Simulink platform to assess the effectiveness of the suggested TMI. Furthermore, a comparison between the suggested TMI circuit and other recent TMI designs with similar characteristics is performed. This comparison is carried out to assess and validate the superior features of the proposed TMI over the alternative designs. © 2024 Elsevier B.V.Item Implementation of novel toroidal transformer-based single-phase multilevel inverter(Springer Science and Business Media Deutschland GmbH, 2024) Nageswar Rao, B.; Yellasiri, Y.; Shiva Naik, B.; Aditya, K.Multilevel inverters (MLIs) have gained traction for their application in high-voltage AC systems and renewable energy. They use fewer DC sources and switches in transformer-based designs to attain the necessary output voltage magnitude. Creating an efficient, high-gain MLI with reduced sources and switches demands meticulous design and substantial effort. This paper introduces a new multilevel inverter design utilizing a toroidal transformer with a reduced number of components. The new topology incorporates ten transistors and a single toroidal transformer. These components are arranged as two H-bridge modules and a bidirectional switch with a transformer to generate nine voltage levels. Notably, the inclusion of three complementary switch pairs in the inverter circuit simplifies the control strategy of the proposed inverter. This configuration enables the inverter to achieve more voltage levels and higher voltage gain using fewer components. Comparison with other existing nine-level inverters highlights the effectiveness of the new design in minimizing the cost function value. The performance assessment of the proposed inverter employs a cost-effective solution. Simulation and experimental results are provided to showcase the practicality and efficiency of the proposed nine-level inverter. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.Item A Transformerless Bidirectional Active Switched Inductor-Based SEPIC High-Gain DC–DC Converter With Buck–Boost Capability(Institute of Electrical and Electronics Engineers Inc., 2025) Mandal, S.; Prabhakaran, P.; Dominic, D.A.; Parameswaran, A.P.The growing demand for efficient and compact power conversion systems in electric vehicles (EVs), renewable energy systems, DC microgrids, and both portable and stationary medical equipment has intensified research into non-isolated high-gain bidirectional DC-DC converters. Existing solutions often employ transformer-based topologies or coupled inductors, which introduce increased cost, size, and control complexity. This paper presents a novel transformerless bidirectional high-gain DC-DC converter based on a modified Single-Ended Primary Inductor Converter (SEPIC) architecture. The proposed topology incorporates an Active Switched Inductor (ASL) at the input stage to achieve a wide voltage conversion ratio while ensuring reduced voltage stress on the maximum power switches. A key feature of the converter is its ability to provide bidirectional buck–boost operation in both power flow directions, while maintaining a reduced component count and improved efficiency through synchronous rectification. The converter’s performance is thoroughly analyzed under both continuous conduction mode (CCM) and discontinuous conduction mode (DCM). Furthermore, detailed small-signal modeling and closed-loop controller design are developed for both voltage-mode and current-mode control. A 200 W experimental prototype employing SiC MOSFETs is implemented to validate the theoretical analysis. Experimental results confirm the high efficiency, robust dynamic response, and practical feasibility of the proposed converter for next-generation power conversion applications. © 2013 IEEE.Item Design and implementation of novel multilevel inverter with full DC-utilization(Taylor and Francis Ltd., 2025) Nageswar Rao, B.; Yellasiri, Y.; Aditya, K.; Shiva Naik, B.S.; Karunakaran, E.This paper presents a novel single-source transformer-based nine-level (9 L) inverter configuration. The design incorporates a three-level neutral-point-clamped (3 L NPC) inverter, a 3-L full bridge, and a transformer to produce 9 L output voltage levels. In particular, one of the 2 L legs in the full bridge is common among the transformer and the load. The proposed structure minimises the components compared to existing transformer-based nine-level inverters. Thus, the suggested inverter volume, cost, and complexity are minimised. Furthermore, a pulse width modulation method has been developed to generate the necessary gating pulses for the proposed inverter. Additionally, a complete comparison study illustrates the enhanced performance of the suggested architecture. The validity of the suggested 9 L inverter is assessed by performing MATLAB simulations and using a scaled prototype. The results obtained from the simulations and experimental tests are then presented and analysed. A clear correlation was observed between the simulation and the hardware results. © 2024 Informa UK Limited, trading as Taylor & Francis Group.