Faculty Publications
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Item A high efficiency on-chip reconfigurable Doherty power amplifier for LTE communication cells(John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2018) Kumar, R.; Kanuajia, B.K.; Dwari, S.; Kumar, S.; Song, H.In this paper, a high efficiency on-chip reconfigurable Doherty power amplifier (DPA) with proposed topology is proposed for LTE or 4G communication cells. The proposed DPA consists of input driver topology, hybrid coupler, asymmetric amplifiers, and 1:1 balun filtered network. The proposed input driver circuit provides wide amplified signal operation within range of 2.3GHz to 6GHz with flat gain of 33 dB. The amplified signal is unsteadily divided into two paths toward the carrier and the power amplifier by 900 hybrid couplers and demonstrates 27.6 dB and 28.3 dB of gain along with 83.2% and 84.5% of power added efficiency at average output power of 40 dBm. The high efficiency and almost flatness in gain stability of proposed DPA providing better solution in order to overcome the interference and the broadband issues for LTE communication cells. The balun-filtered network is employed for combined the two outputs of carrier and peak amplifiers that provides more uniform desired band of operation in the frequency responses. The proposed DPA circuit are implemented and optimized by using advanced design RF simulator platform. The fabricated chip is made by using 0.13 ?m GaN HEMT on Si-Nitride monolithic microwave integrated circuit die process. The fabricated chip of DPA provides 85% of PAE with 28 dB gain which are made close agreement with simulation results. The size of chip is 2.8*1.2mm2 which occupies less die area as compared to existing DPAs. © 2018 Wiley Periodicals, Inc.Item Improved SuDoKu reconfiguration technique for total-cross-tied PV array to enhance maximum power under partial shading conditions(Elsevier Ltd, 2019) Sai Krishna, G.; Moger, T.Mismatch losses ignore the performance of individual photovoltaic (PV) modules and cut back most of the power from the PV array. These losses mainly due to partial shading condition (PSC), are caused by the reduction of spacing between PV modules, passing clouds, and near buildings, etc. Several techniques are present in the literature to cut back the partial shading issues. One of the most effective methods is the reconfiguration techniques, namely reconfigure the location of PV modules in PV array so as to distribute partial shading effects and increase the maximum power output. This paper proposes an Improved SuDoKu reconfiguration pattern for 9×9 Total-Cross-Tied (TCT) PV array to enhance maximum power output under partial shading conditions. The main aim of this approach is to arrange the PV modules in TCT array according to the SuDoKu pattern without altering the electrical connections. Further, the performance of the proposed pattern is evaluated with different existing PV array configurations by comparing the Global Maximum Power Point (GMPP), Mismatch Losses (ML), Fill Factor (FF) and Efficiency (?). Based on the results of this paper, it is concluded that the proposed improved SuDoKu PV array arrangement enhances the global maximum power under all shading conditions. © 2019 Elsevier LtdItem Enhancement of maximum power output through reconfiguration techniques under non-uniform irradiance conditions(Elsevier Ltd, 2019) Sai Krishna, G.; Moger, T.Partial shading is one of the major drawback which diminishes the power output of the PV array. One of the effective methodologies is reconfiguration strategies, namely shifting the location of PV modules from one place to different places so as to distribute shading effects over the array to increase maximum power output under PSCs. This paper proposed two novel puzzle arrangements followed by Ken-Ken (KK) and Skyscraper (SS) for 4×4 total-cross-tied (TCT) PV array and increase maximum power under PSCs. In this approach, the PV modules in the TCT array is arranged according to Ken-Ken and Skyscraper arrangements without changing the electrical connections. Further, the performance of the proposed arrangements are investigated with different existing PV array configurations by comparing the global maximum power point (GMPP), the voltage at global maximum power point (VGMPP), mismatch losses (ML), fill-factor (FF), efficiency (?) and possible local peaks (PLP) under different shading patterns using Matlab-Simulink. An extensive simulation study is carried out on these configurations under different shading patterns as well as temperatures. Also, a comprehensive comparison has done for various reconfiguration schemes presented in literature. The result shows that the proposed arrangements are enhancing the global maximum power as compared to the other existing configurations. © 2019 Elsevier LtdItem Optimal SuDoKu Reconfiguration Technique for Total-Cross-Tied PV Array to Increase Power Output under Non-Uniform Irradiance(Institute of Electrical and Electronics Engineers Inc., 2019) Sai Krishna, G.; Moger, T.Partial shading condition drastically reduces the maximum power output of photovoltaic array. Partial shading occurs due to several factors, such as flying birds, trees, and passing clouds. Many ways can be mitigated partial shading problems in photovoltaic (PV) array. One among the way is reconfiguration techniques, namely reconfigure the location of PV modules in PV array based on irradiance levels in order to distribute shading effects and increasing maximum power. This paper proposed an optimal SuDoKu reconfiguration pattern for 9\times 9 total-cross-Tied (TCT) PV array to improve maximum power under partial shading conditions. In this approach, the physical location of PV modules in TCT array are rearranged based on optimal SuDoKu style without altering the electrical connections, so that the shading effects can distribute over the array. Further, the performance of proposed pattern investigated with existing SuDoKu pattern under different shading conditions by comparing the global maximum power point, mismatch losses, fill-factor, and efficiency using MATLAB-Simulink. Based on the results of this paper, it concluded that the proposed optimal SuDoKu reconfiguration arrangement is reducing the wiring arrangement and increasing the shading distribution over the array as compared to SuDoKu arrangement. © 1986-2012 IEEE.Item Enhanced power generation for total-cross-tied pv array using simulated annealing under partial shading conditions(John Wiley and Sons Inc, 2020) Sai Krishna, G.S.; Moger, T.Shade phenomena affect the PV module's power output, introduce multiple peak points in PV characteristics, and shorten the expected life cycle of the module. In order to prevent this issue, PV modules should reconfigure, namely, altering the electrical connections between PV modules based on the irradiance without changing their physical locations. As a result, the shading effects can distribute over the array and increase power output. This paper proposed a novel reconfiguration technique based on the simulated annealing algorithm to distribute shading impacts on 9×9 total-cross-tied (TCT) PV array. In this work, the proposed algorithm produces a reconfigured connection matrix for 9×9 TCT array that can minimize the current differences in each row and improve the power output. Various shading conditions have been taken to investigate the proposed technique by obtained global maximum power point (GMPP), current at GMPP, power loss, fill-factor, and efficiency. Further, the performance of the proposed technique is validated with other existing reconfiguration methods under partial shadings. In comparison with existing methods, the result shows that the proposed simulated annealing enhanced the power generation of the TCT array under all shading patterns. © The Institution of Engineering and Technology 2020.Item A novel adaptive dynamic photovoltaic reconfiguration system to mitigate mismatch effects(Elsevier Ltd, 2021) Sai Krishna, G.; Moger, T.Unequal solar irradiance of the Photovoltaic (PV) modules diminishes the PV array's maximum power output; this effect is due to Partial Shading Conditions (PSCs). There are a few technical options to fix this issue. One of these is the dynamic reconfiguration technique, which means that the electrical connections between the PV modules in the array are dynamically modified to spread shading effects and increase the power output. This paper proposed a novel adaptive reconfiguration method for 3×3 Total-Cross-Tied (TCT) PV array to enhance the maximum power under partial shading conditions. In this work, the PV module's electrical connections are altered dynamically with the proposed logic algorithm's help to maintain the identical row currents in the array. This technique is implemented on 3×3 size of an array using MATLAB and validated experimentally using OPAL-RT software. Further, the proposed technique performance is compared with the existing PV array connections such as Series-Parallel (SP), Total-Cross-Tied (TCT), Bridge-Link (BL), Honey-Comb (HC), and Shade Dispersion Positioning (SDP). Additionally, for different reconfiguration methods, revenue generation from energy savings is estimated. Based on the observations from the results, it is understood that the proposed technique enhanced the maximum power of the TCT array at a higher level as compared to the other PV array connections under PSCs. © 2021 Elsevier LtdItem A Reduced Component Count Self-Balance Quadruple Boost Seventeen-Level Switched Capacitor Inverter(Institute of Electrical and Electronics Engineers Inc., 2024) Ahmed, S.; Raushan, R.; Ahmad, M.W.A switched capacitor multilevel inverter (SCMLI) enables high-quality output voltage waveforms for various industrial and renewable energy applications. SCMLI uses a combination of capacitors and switches to generate multiple voltage levels from a single dc source, thereby reducing the overall cost and size of the system. This article proposes a novel configuration of a 17-level SCMLI. The proposed converter can boost four times the input voltage by exploiting the series-parallel connection of capacitors with the dc voltage source. With simple pulsewidth modulated (PWM) control, the capacitor voltages are inherently balanced under different loading conditions. Furthermore, for 11 switches, only seven independent switching signals are required. Loss analysis reveals that the proposed SCMLI has significantly reduced conduction losses, capacitor ripple voltage, voltage stress, and cost function (CF) when compared with other topologies available in the literature. Finally, the simulation results are obtained at different loads and modulation indexes. The results are experimentally validated with a scaled-down laboratory prototype. © 2024 Institute of Electrical and Electronics Engineers Inc.. All rights reserved.Item Modified Odd–Even–Prime pattern for effective dispersion of shade over the PV array under partial shading conditions(Elsevier Ltd, 2024) Ramesh, D.; Karthikeyan, A.Photovoltaic (PV) arrays are extensively used for power generation being the most abundant renewable energy sources available. Partial shading of the PV array leads to mismatch between the modules and decrease in output power. A new Modified Odd–Even–Prime (MOEP) method of module arrangement for total cross tied (TCT) connection is presented in this paper to mitigate the effects of partial shading. The proposed MOEP method is a physical relocation method where the modules of PV array are relocated without altering the electrical connections. MOEP method of module rearrangement is based on row positions of the PV array. In this method, the row positions of PV modules in the first column are filled with odd, even and prime numbers in ascending order. The row positions of further columns are formed based on MOEP method. The proposed MOEP method is implemented on 9 × 9 and 8 × 8 PV arrays under various shading patterns. Further, the results are compared with TCT, Odd Even (OE) and Odd–Even–Prime (OEP) patterns. MATLAB/Simulink is used to validate the results. An experimental setup of 9 × 9 and 8 × 8 PV array is developed and tested in real time environment to validate the effectiveness of MOEP method over TCT, OE and OEP methods. The performance of proposed MOEP method is evaluated in terms of GMPP, mismatch power loss (MPL), Fill Factor (FF), Efficiency (η) and Shade Dispersion Ratio (SDR). A detailed study on energy savings from the proposed MOEP method is made on hourly, daily and yearly basis. From the experimental results obtained, it is observed that MOEP method generates a significant improvement in GMPP, efficiency and reduces the mismatch loss compared to TCT, OE and OEP methods. © 2024 International Solar Energy SocietyItem A new design approach of Rat-Race coupler based compact GaN HEMT power amplifier towards flat high efficiency over broadband(Elsevier GmbH, 2024) Gupta, M.P.; Kumar, S.; Naik Jatoth, D.; Gorre, P.; Song, H.This paper presents a high efficiency Rat-Race Coupler based compact GaN HEMT power amplifier (PA) design over broadband for high power transmitter in wireless communication. The rat-race coupler integrated PA Compact design is proposed for the first time as per author best knowledge. The design methodology used a higher order two open stubs and a rat-race coupler (RRC) at input/output sections to control harmonics impedances. The RRC is used to enhance the i/o power, and efficiency over broadband, which provides a good insertion loss, and consumes the least power and non-crucial impedance bandwidth for the normalized frequency band of interest. As a proof of concept, a PA is fabricated using a monolithic microwave integrated circuit (MMIC) 0.15 µm gallium nitride high electron mobility transistor (GaN HEMT) process. The measured result shows that the designed PA achieves a flat power added efficiency (PAE) of 65 % − 74 %, output power (Pout) of 44.8 dBm − 46 dBm, and drain efficiency (DE) of 72 % − 85 %, over a record wide frequency of 1.8 GHz − 3.6 GHz, which is the highest one among all reported harmonic tuned PAs. © 2024 Elsevier GmbH