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 Implementation of Single-Phase Two-Switch Midpoint Unidirectional Multilevel Converter System(Walter de Gruyter GmbH, 2018) Roy, P.R.; Parthiban, P.; Babu, B.This paper deals with implementation of a single-phase three level converter system under low voltage condition. The frequency of the switches is made constant and involves change in $-t-on}}$ton and $-t-off}}$toff duration. For this condition the pulse width modulation control scheme for a single phase three level rectifier is developed to improve the power quality. The hysteresis current control technique is adopted to bring forth three-level PWM on the dc side of the bridge rectifier and to achieve high power factor and low harmonic distortion. Based on the proposed control scheme, the line current is driven to follow the sinusoidal current command which is in phase with the supply voltage. By using three-level voltage pattern the blocking voltage of each power device is clamped to half of the dc link voltage. The simulation and experimental results of 20W converter under low input voltage condition are shown to verify the circuit performance. Open loop simulation and hardware tests are implemented by applying a low voltage of 15 V(rms) on the input side. © 2018 Walter de Gruyter GmbH, Berlin/Boston 2018.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 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 compact and efficient graphene FET based RF energy harvester for green communication(Elsevier GmbH, 2020) Singh, N.; Kumar, S.; Kumar Kanaujia, B.K.; Beg, M.T.; Mainuddin, M.; Kumar, S.This paper presents a graphene field effect transistor (FET) based rectenna with substrate-integrated waveguide (SIW) broadband approach for RF energy harvesting application. The proposed structure of integrated rectenna consists of a graphene FET rectifier and an SIW antenna operating in the (S11 < ?10 dB) range of 29–46 GHz. The peak gain of the SIW antenna observed is 8.12 dBi. In addition, a new matched circuit consisting of microstrip line and butterfly stub (without using any lumped elements) is designed. The matched circuit provides a miniaturized block by reducing the size and eliminating parasitic reactance in the integrated rectenna. The proposed rectenna is implemented and fabricated using two superimposed layers: RT/duroid 5880 and graphene substrate with a compatible approach. A measured conversion efficiency of 80.32% is obtained. The dimensions of the proposed antenna and rectifier are 3.2 × 3.2 × 0.4 mm3 and 3.2 × 10 × 0.4 mm3, respectively. The proposed rectenna covers Ka- and Q-band applications and could be a potential candidate for contemporary energy harvesting systems. © 2019 Elsevier GmbHItem 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.Item A compact broadband GFET based rectenna for RF energy harvesting applications(Springer, 2020) Singh, N.; Kumar, S.; Kumar Kanaujia, B.K.; Beg, M.T.; Mainuddin, M.; Kumar, S.In this paper, a compact GFET-based rectifier integrated with a monopole antenna is proposed for wireless energy harvesting applications. The GFET increases impedance bandwidth of the rectifying circuit, thus covering a range of 22.5–27.5 GHz. The sensing antenna is a triangular monopole with truncated corners for realizing circular polarization at the frequencies 24.25 GHz and 27 GHz. By the help of ?/4 transformer, the sensing antenna is matched with the proposed GFET rectifier. The RF-DC conversion efficiency realized is 80% at 5 dBm for the load of 5 K?, and the output DC voltage observed is 6.8 V. The modified ground plane triangular monopole antenna shows a peak gain of 7.8 dBi. The designed rectenna prototype is fabricated and found simulated and measured results are in good agreement. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.Item Design of coupled inductors using split winding scheme for bridgeless SEPIC(Institution of Engineering and Technology jbristow@theiet.org, 2020) Prabhu, P.; Urundady, V.A bridgeless single-ended primary inductance converter (SEPIC) is a highly preferred single-stage front-end AC-DC converter for applications requiring a wide variation of DC voltage because it also gives improved performance in terms of the quality of supply current. This study presents the design of coupled inductors for the bridgeless SEPIC using the split winding scheme. With coupling incorporated the required value of self-inductances of the input and output inductors for the same performance is reduced. Also, they can be wound on the same core, thereby resulting in a reduction in size. The conventional method of tuning the coupling coefficient by adjusting the air-gap is tedious. A split winding scheme for the distribution of windings over three limbs of E-core for obtaining the desired coupling coefficient is presented. The split winding scheme for the design of coupled inductors for bridgeless SEPIC converter rated for 500 W, 20 kHz is illustrated. The effect of coupling on the volume, weight, cost, and efficiency of the converter is compared with the conventional SEPIC converter without coupling for a similar performance. The performance of the proposed converter is evaluated using MATLAB/Simulink simulation and experimental results with a laboratory prototype rated for 500 W. © The Institution of Engineering and Technology 2020.