Faculty Publications
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Publications by NITK Faculty
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Item An analytical model for intersystem handover(Institute of Electrical and Electronics Engineers Inc., 2003) Singh, B.; Aggarwal, K.K.; Kumar, S.Universal Mobile Telecommunication Systems (UMTS) shall be developed in such a way that it will support compatibility with an evolved Global System for Mobile Communications (GSM). In this paper, we investigate intersystem handover between GSM and UMTS based on Wideband Code Division Multiple Access (WCDMA) air-interface. A mathematical model is proposed to evaluate the handover performance. The handover initiation algorithm is based on the absolute value of averaged signal strength thresholds. Average number of handovers and handover initiation delay are used as performance measures. Based on numerical results, it is observed that handover initiation algorithm based on absolute thresholds induces large number of handovers near the cell boundary. Finally, threshold levels are optimized for given system parameters.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 Improvement in Harmonic Reduction of 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.S.; Kalpana, R.; Singh, B.To improve the harmonic reduction ability in input line current of 12-pulse diode bridge rectifier (DBR) using zigzag autoconnected transformer with a dc side current injection technique is presented in this paper. Conventional 12-pulse rectifier does not meet the IEEE-519 standard and therefore current injection technique at dc side is used to shape the system current waveform to minimize the harmonic distortion in the input line current. The proposed configuration uses zigzag autoconnected transformer with inherent ability of blocking zero-sequence components which eliminate the requirement of zero sequence blocking transformer (ZSBT). The current injection circuit with interphase reactor (IPR) enables to alter dc current at the rectifier output which further shapes input line currents to near sinewave. The proposed configuration is designed, simulated and analyzed in MATLAB/SIMULINK. Simulation results of proposed configuration for variation in current injection and load on input line current harmonic suppression, power quality parameters are presented in this paper. © 2016 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 Design and analysis of solar photovoltaic array fed modular full-bridge DC-DC converter for 12 kW SMPC(Institute of Electrical and Electronics Engineers Inc., 2018) P, P.S.; Kalpana, R.; Singh, B.This paper discusses the solar photovoltaic (SPV) array fed switched mode power converter (SMPC) using a modular full-bridge dc-dc converter as an intermediate converter. Among the different types of dc-dc converters, the straightforward and uncomplicated boost converter is selected in order to obtain the maximal power from the SPV array. The straightforward boost converter with reduced part count has inherent features of minimizing the output current ripples and possessing an unbounded region for maximum power point extraction. The improved efficiency of the converter is achieved by designing the SPV array to deliver maximum power at rated dc voltage and maximum switch utilization of the boost converter. The design, analysis and operating modes are explained for the proposed converter and the performance is validated through MATLAB/Simulink based simulation. © 2017 IEEE.Item Low Frequency Ripple Charging of Li-Ion Battery using Bidirectional Zeta DC-DC Converter to Improve Charge Transfer Efficiency(Institute of Electrical and Electronics Engineers Inc., 2018) Goud, J.S.; Kalpana, R.; Kiran, R.; Singh, B.Li-ion batteries are the most popular rechargeable batteries in applications like consumer electronics and electric vehicles in comparison with other rechargeable battery chemistries due to its high specific energy and longer life cycle. The reliability and life of the battery power devices depends on state of charge (SOC) and the charging protocol used for charging the battery. In this paper, low frequency ripple current (LFRC) charging of Li-Ion battery using the Zeta bi-directional DC-DC converter is presented. Charging the battery at the optimal frequency with ripple current results in improved charge transfer efficiency, improved charging time and thereby improves the life of the battery. To realize the LFRC charging technique, Zeta bidirectional converter and mathematical model of 48V, 4Ah Li-Ion battery is designed and simulated in MATLAB/ Simulink platform. Moreover, an experimental prototype is developed to validate the LFRC charging technique. © 2018 IEEE.