Faculty Publications
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Publications by NITK Faculty
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Item An improved power quality converter for three-phase switched mode power supplies(IEEE Computer Society help@computer.org, 2014) Kalpana, R.; Singh, B.; Bhuvaneswari, G.In this paper, an improved power quality converter is presented for harmonic mitigation in SMPS (Switched Mode Power Supply) for telecom power applications with reduced kVA rating. The proposed ac-dc converter is found capable of suppressing less than 23rd harmonic in the supply current along with the power factor improvement close to unity in the wide operating range. The effect of load variation on the SMPS is studied to demonstrate the performance and effectiveness of the improved converter. © 2014 IEEE.Item High-efficiency improved 12kW switched mode telecom rectifier(Institute of Electrical and Electronics Engineers Inc., 2016) P, P.; Kalpana, R.; Singh, B.; Bhuvaneswari, G.In this paper an improved switched mode telecom rectifier for a 12kW telecommunication system is presented. An improved telecom rectifier is a combination of phase-shift transformer based ac-dc converter and passive high pass filter. The phase-shift transformer and high pass filter is realized with a fractional magnetic rating of the load. The supply current is almost sinusoidal with low total harmonic distortion, and the power factor (PF) is close to unity. The complete design of phase-shift transformer based ac-dc converter and passive high pass filter is presented in this paper. The 12kW telecom rectifier is designed, modeled and simulated to reduce the total harmonic distortion (THD) of the input ac mains current and to improve the power factor. A laboratory prototype of phase-shift transformer based ac-dc converter is developed and the results are presented to validate the design topology. © 2015 IEEE.Item High performance front-end PFC rectifier for telecom power supplies(Institute of Electrical and Electronics Engineers Inc., 2017) P, P.; Kalpana, R.; Singh, B.; Bhuvaneswari, G.High-current low-voltage (HCLV) rectifiers are used in the telecom industries, electroplating and induction heating system. Typical power rating of these rectifiers varies from tens of kW to hundreds of MW. In this paper, a three-phase three-level boost type PWM rectifier is proposed as an active front-end PFC scheme for telecom load. The proposed active front-end PFC converter is modeled by switching cycle average model and relation between duty ratio and the dc-link capacitor voltage is derived as in terms of system input currents. Also, the switching states have been derived for the feasible converter operation. The detailed analysis of front-end PFC converter is carried out by equivalent circuit. The power quality also well improved by proposed active front-end PFC rectifiers. The experimental setup for a 12 kW active front-end PFC rectifier is developed in the laboratory to validate the MATLAB simulation results. © 2016 IEEE.Item Current injection based front-end power quality improved converter for telecom load(Institute of Electrical and Electronics Engineers Inc., 2017) P, P.; Kalpana, R.; Singh, B.; Bhuvaneswari, G.In this paper a front-end converter having third harmonic current injection technique is used for improving input current shape as near sinusoidal. Here zig-zag transformer is used as the current injection device so that the advantages pertaining to zig-zag transformer is utilized effectively. The third harmonic current injection device along with the three-level boost converter at the output stage will increase the dc-link voltage and the current is injected through zig-zag transformer. The power quality is well improved using third harmonic current modulated front-end structure which is very well applicable to telecom load having the high current low voltage. Extensive simulation is carried out for the 12 kW load and the results are verified through experimental setup. The experimental setup is tested for reduced voltage rating and the test results are presented. © 2016 IEEE.Item Power quality improvement in front-end hybrid AC-DC converter based on current injection technique(Institute of Electrical and Electronics Engineers Inc., 2017) P, P.; Kalpana, R.; Singh, B.; Bhuvaneswari, G.This paper highlights the power quality issues and explains the remedial measures taken by means of hybrid frontend third harmonic current injection rectifiers. Here zig-zag transformer is used as the current injection device so that the advantages pertaining to zig-zag transformer is utilized effectively. The third harmonic current injection device along with the three-level boost converter at the output stage will increase the dc-link voltage. Also, the power quality is well improved using third harmonic current modulated front-end structure which is well appropriate to medium/higher power applications. The experimental prototype of hybrid front-end PFC rectifier is developed in the laboratory to validate the MATLAB simulation results. © 2017 IEEE.Item Design and Implementation of Sensorless Voltage Control of Front-End Rectifier for Power Quality Improvement in Telecom System(Institute of Electrical and Electronics Engineers Inc., 2018) P, P.S.; Kalpana, R.; Singh, B.; Bhuvaneswari, G.In this paper, a three-phase three-switch three-level boost (Vienna) type pulse-width modulation rectifier is proposed as an active front-end power factor correction (PFC) rectifier for power quality improvement in telecom load. A sensorless voltage control technique is proposed and it does not rely on any input voltage information results in reliable and robust operation. A brief description on the principle of operation and the most advantageous modulation method of the proposed system are discussed. The feasible switching states are identified for the proposed active front-end converter resulting in reduced switching stress and dc ripples. A triangular carrier based control logic is applied and the input current reaches sinusoidal shape without the need of sensing the input voltage. The detailed analysis of front-end PFC converter is carried out by equivalent circuit analysis. Also, the complete loss and efficiency calculation of the converter is explicitly carried out with the help of hardware design guidelines. The performance of the proposed system and its capability of operating satisfactorily in the event of failure of one phase of the mains is verified through MATLAB Simulation, and the results obtained are presented. The experimental setup rated for 9 kW is developed in the laboratory to validate the simulation results. From the simulation and hardware results, it is observed and recorded that the power quality parameters are improved and are well within the IEEE and IEC standards. © 1972-2012 IEEE.Item Power Quality Improvement in Utility Interactive Based AC-DC Converter Using Harmonic Current Injection Technique(Institute of Electrical and Electronics Engineers Inc., 2018) P, P.S.; Kalpana, R.; Singh, B.; Bhuvaneswari, G.This paper highlights the power quality issues and explains the remedial measures taken by means of hybrid front-end third harmonic current injection rectifiers. Here, a zig-zag transformer is used as the current injection device so that the advantages pertaining to the zig-zag transformer are effectively utilized. The third harmonic current injection device along with three-level boost converter at the output stage will increase the dc-link voltage. With less boost inductance, generally half of the conventional boost converter inductance is sufficient to implement the proposed converter structure resulting in reduced ripple current and also the device rating is reduced by half of the output voltage. Moreover, the power quality is well improved using third harmonic current modulated front-end structure, which is well appropriate for medium/higher power applications. The experimental prototype of hybrid front-end converter is developed in the laboratory to validate the MATLAB 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 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 Internal damage growth in quasi-brittle fibre-reinforced cementitious materials under cyclic compressive loading(Structural Engineering Research Centre, 2023) Vidya Sagar, R.; Basu, D.J.; Suhas Reddy, K.V.; Prathap, Y.; Bhuvaneswari, G.; Sai Keerthi, P.This article reports a comparison between the internal damage growth in cementitious materials without fibres and with fibres subjected to elevated amplitude cyclic compressive loading. The damage progression was assessed using ultrasonic testing method and Acoustic Emission (AE) testing. The intricate fracture mechanism in the test specimens causes rise to a higher harmonic generation, which was used as an indicator to the internal damage. The decrement in wave peak amplitude with higher harmonic generation may be regarded as a ‘internal damge growth’ in the deformable solid. The complexity in the fracture mechanism in fibrous cementitious matrix influenced the heterogeneity of the specimen, which is reflected by the steep decrement in the slope of the line plotted using normalized higher harmonic ratio and load. It was observed that the ‘magnitude of the total damage’ developed in plain concrete at the last loading phase was relatively lower than brass coated steel fibre reinforced concrete. This was supported by the damage parameter based on generated AE, where final failure of the specimens preceded an AE avalanche. Therefore, the utilization of a combination of nondestructive testing techniques such as AE and nonlinear ultrasonic testing can offer a more comprehensive understanding of the progression of damage in quasi-brittle cementitious materials. © 2023, Structural Engineering Research Centre. All rights reserved.