Faculty Publications
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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 Design and Development of Multi-Phase Rectifier with Reduced Magnetic Rating(Institute of Electrical and Electronics Engineers Inc., 2018) P, P.S.; Kalpana, R.; Singh, B.This paper proposes a 20-pulse asymmetric multiphase rectifier (AMPR) suitable for medium and high-power applications. Unlike the other state-of-the-art 20-pulse delta connected autotransformers, the proposed delta connected AMPR has an ability to reduce input harmonics, maintains high efficiency and requires a magnetic rating of only 30.12% of the nominal load thereby a significant reduction in space, weight, and overall cost required are the salient features of the proposed AMPR. Firstly, the proposed AMPR configuration is simulated in MATLAB/Simulink environment for evaluating its viability under different loading conditions, and the results are illustrated. Also, a prototype is developed, and the experimental measurements obtained are presented to validate the feasibility and operability of the proposed AMPR. The proposed AMPR offers a total harmonic distortion of 3.7% and can operate at near-unity power factor complying with the IEEE and IEC standards. © 2018 IEEE.Item A 36-Pulse AC-DC Converter with DC Side Tapped Interphase Bridge Rectifier for Power Quality Improvement(Institute of Electrical and Electronics Engineers Inc., 2018) P, P.S.; Kalpana, R.; Chethana, K.S.; Singh, B.This paper presents a circuit configuration to reduce the harmonic contents at the AC mains of a 12-pulse zigzag configured autotransformer based DBR. The proposed circuit configuration employs a tapped interphase bridge rectifier at the DC side of 12-pulse DBR that results in higher pulses in the supply current. Thus, reducing the harmonic content and thereby improving the power quality of the system. Since the autotransformer employed is zigzag configured, the need for ZSBT is eliminated. Moreover, the proposed circuit configuration at the DC side shapes the supply current near to a sine wave. Further, the proposed configuration is analyzed, 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 IEEE.Item Investigations on Single-Phasing Effect of Zigzag Autoconfigured Transformer Based 12-Pulse Rectifier(Institute of Electrical and Electronics Engineers Inc., 2018) Kalpana, R.; P, P.S.; Vidyasagar, V.S.; Singh, B.High power industrial loads are often fed from front-end multi-pulse rectifier as its ability to effectively and inexpensively mitigate the harmonics on the AC side is achieved by the multi-pulse autoconfigured transformer. This paper analyzes and investigates the operability of the zigzag autoconfigured transformer based 12-pulse rectifier when one of the input terminals is open, i.e., single-phasing. Contrary to the prior art multi-pulse rectifiers, the availability of neutral point in zigzag autoconfigured transformer results in normal operation at DC side during single-phasing. A detailed MATLAB Simulation is carried out to understand the single-phasing operation of the zigzag autoconfigured transformer. Further, the experimental results from the laboratory prototype are presented to validate the simulated results. © 2018 IEEE.Item Power Quality Enhancement in AC-DC Converter Using Voltage Sensorless Control Technique(Institute of Electrical and Electronics Engineers Inc., 2018) P, P.S.; Kalpana, R.; Singh, B.This paper presents the power quality improvement in power supply systems and explains the corrective measures taken by means of front-end AC-DC converter. The front-end AC-DC converter having a boost type delta connected rectifier with voltage sensorless control technique is proposed. The delta switch rectifier enables the zero-sequence component circulation and thereby reduces the third harmonic component in the input mains. Further, the input voltage sensorless control is developed for the proposed converter which can maintain the power quality well within the IEEE and IEC standards and also, yields lesser switching loss, reduced switching stress and high output voltage. The performance of the front-end AC-DC converter configuration is validated by simulating in the MATLAB Simulink environment and the results are presented. The experimental setup for the front-end AC-DC converter is implemented in the laboratory to validate the MATLAB simulation results. © 2018 IEEE.Item Third Harmonic Current Injection Based Front-End AC-DC Converter for Power Quality Improvement in DC Distribution Systems(Institute of Electrical and Electronics Engineers Inc., 2020) Prakash, P.S.; Kalpana, R.; Singh, B.This paper presents the design and implementation of a three-phase buck type unity power factor rectifier used for distribution systems. The AC-DC converter topology considered in this paper is named as SWISS rectifier, consists of front-end three-phase diode bridge rectifier with active current injection circuit and back-end DC-DC buck converter. The characteristics of the AC-DC converter topology, including the principle of operation, modulation schemes, conduction state analysis, and control strategy are discussed in detail. Further, the analytical expression for the loss calculation is performed. Extensive simulation is carried out for the converter system, and the practicability of the converter system is verified by conducting a test on the constructed hardware prototype. © 2020 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 Three-phase three-level boost-type front-end PFC rectifier for improving power quality at input AC mains of telecom loads(Korean Institute of Power Electronics editor@kipe.or.kr, 2018) P, P.; Kalpana, R.; Singh, B.A three-phase, three-switch, and three-level boost-type PWM rectifier (Vienna rectifier) is proposed as an active front-end power factor correction (PFC) rectifier for telecom loads. The proposed active front-end PFC rectifier system is modeled by the switching cycle average model. The relation between duty ratios and DC link capacitor voltages is derived in terms of the system input currents. Furthermore, the feasible switching states are identified and applied to the proposed system to reduce the switching stress and DC ripples. A detailed equivalent circuit analysis of the proposed front-end PFC rectifier is conducted, and its performance is verified through simulations in MATLAB. Simulation results are verified using an experimental setup of an active front-end PFC rectifier that was developed in the laboratory. Simulation and experimental results demonstrate the improved power quality parameters that are in accordance with the IEEE and IEC standards. © 2018, Korean Institute of Power Electronics. All rights reserved.Item Investigations on Open-Circuit Faults of Zigzag Autoconfigured Transformer-Based 12-Pulse Rectifier(Institute of Electrical and Electronics Engineers Inc., 2020) Kalpana, R.; P, S.P.; Vidyasagar, V.S.; Singh, B.High power industrial loads are often fed from front-end multipulse rectifier as its ability to effectively and inexpensively mitigate the harmonics on the input ac side, which is achieved by the multipulse autoconfigured transformer. This article analyzes and investigates the operability of the zigzag autoconfigured transformer-based 12-pulse rectifier under open-circuit faults at input ac terminals. Contrary to the prior art 12-pulse rectifiers, the availability of neutral point in zigzag autoconfigured transformer results in different modes of operation under open-circuit faults at input terminals. A detailed theoretical analysis is carried out to understand the operation of the zigzag autoconfigured transformer-based 12-pulse rectifier under open-circuit fault conditions. Further, the experimental results are presented from the laboratory prototype to validate the theoretical analysis. © 1972-2012 IEEE.