Implementation of a Switched PV Technique for Rooftop 2 ㎾ Solar PV to Enhance Power during Unavoidable Partial Shading Conditions

B. Praveen Kumar,D. Prince Winston,S. Cynthia Christabel,S. Venkatanarayanan 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

We propose maximum power extraction from a rooftop solar photovoltaic (PV) array during partial shading conditions. Partial shading is unavoidable during power extraction from rooftop PV systems due to nearby tall buildings (construction of additional floors) and trees (growth of trees). Many reconfiguration techniques can be used to extract maximum power in partial shading conditions, but in several cases, the real maximum power output is not achieved. In this study, a new switched PV technique is proposed to enhance the power output. The proposed technique is simple to use and more cost effective than other reconfiguration techniques. Therefore, it is suitable for rooftop applications. The power output of the proposed technique is compared with that of existing techniques with similar shading patterns. Eight panels with ratings of 250 watts (2 kW) each are used for testing. MATLAB simulation and hardware verification are done for the proposed and existing techniques. The proposed technique is implemented on a 4×2 PV array, although it can be extended to a number of arrays.

Implementation of a Switched PV Technique for Rooftop 2 kW Solar PV to Enhance Power during Unavoidable Partial Shading Conditions

B. Praveen Kumar,D. Prince Winston,S. Cynthia Christabel,S. Venkatanarayanan 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

We propose maximum power extraction from a rooftop solar photovoltaic (PV) array during partial shading conditions. Partial shading is unavoidable during power extraction from rooftop PV systems due to nearby tall buildings (construction of additional floors) and trees (growth of trees). Many reconfiguration techniques can be used to extract maximum power in partial shading conditions, but in several cases, the real maximum power output is not achieved. In this study, a new switched PV technique is proposed to enhance the power output. The proposed technique is simple to use and more cost effective than other reconfiguration techniques. Therefore, it is suitable for rooftop applications. The power output of the proposed technique is compared with that of existing techniques with similar shading patterns. Eight panels with ratings of 250 watts (2 kW) each are used for testing. MATLAB simulation and hardware verification are done for the proposed and existing techniques. The proposed technique is implemented on a 4×2 PV array, although it can be extended to a number of arrays.

Surface characterization of 2-hydroxypyrimidine sulphate by inverse gas chromatography

B. Praveen Kumar,K. S. Reddy,T. Madhusudana Reddy 한국약제학회 2014 Journal of Pharmaceutical Investigation Vol.44 No.1

The net retention volumes, VN, of n-alkanes andpolar probes on 2-hydroxypyrimidine sulphate (2-HPS)drug surface are determined at 323.15, 328.15 and333.15 K using inverse gas chromatography. The dispersivesurface free energy, cdSof 2-HPS are evaluated byapplying Schultz method as well as Dorris–Gray methodand found that cdSvalues are higher by 8 per cent in thelatter method. The cdSvalues are decreasing in both themethods with increase of temperature. The specific componentof the free energy of adsorption, DGSa, for polarprobes are obtained by three methods proposed by Schultzet al., Saint Flour–Papirer and Sawyer–Brookman. TheLewis acid–base parameters, Ka and Kb, are calculatedusing DGSavalues. The surface character value, S = (Kb/Ka) according to the Schultz et al., is found to be 3.9whereas the S value in the other two methods are found tobe 6.2 and 5.6. The results demonstrate that the 2-HPSpowder surface contain relatively more basic sites and caninteract strongly in the acidic media.

Combination of Novel Converter Topology and Improved MPPT Algorithm for Harnessing Maximum Power from Grid Connected Solar PV Systems

B. Meenakshi Sundaram,B. V. Manikandan,B. Praveen Kumar,D. Prince Winston 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.2

It is a diffi cult task to utilize the power from the solar PV connected to utility grid eff ectively due to its lower effi ciency. Hence, a new power electronic topology with maximum power point tracking (MPPT) algorithm is needed to reduce the losses thereby obtaining the maximum power from solar PV system. Direct energy transfer is implemented to transfer the rated solar power to the utility grid, the rest is fed to the converter and used for DC loads. In this work, a reversed buck-boost converter topology with parallel power processing concept is used effi ciently and a multiple perturbation and observation (MP&O) based MPPT algorithm is proposed to achieve the global maximum power point (GMPP). And also boost inverter topology is employed by which the power from PV is supplied to the utility grid. The proposed method is simulated using MATLAB/SIMULINK and implemented in hardware. The simulation and experimental results of the proposed MP&O technique provide maximum AC power as well as DC power even in low irradiance and partial shading conditions of the solar PV array compared to the existing techniques.

Implementation of a Switched PV Technique for Rooftop 2 kW Solar PV to Enhance Power during Unavoidable Partial Shading Conditions

Kumar, B. Praveen,Winston, D. Prince,Christabel, S. Cynthia,Venkatanarayanan, S. The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

We propose maximum power extraction from a rooftop solar photovoltaic (PV) array during partial shading conditions. Partial shading is unavoidable during power extraction from rooftop PV systems due to nearby tall buildings (construction of additional floors) and trees (growth of trees). Many reconfiguration techniques can be used to extract maximum power in partial shading conditions, but in several cases, the real maximum power output is not achieved. In this study, a new switched PV technique is proposed to enhance the power output. The proposed technique is simple to use and more cost effective than other reconfiguration techniques. Therefore, it is suitable for rooftop applications. The power output of the proposed technique is compared with that of existing techniques with similar shading patterns. Eight panels with ratings of 250 watts (2 kW) each are used for testing. MATLAB simulation and hardware verification are done for the proposed and existing techniques. The proposed technique is implemented on a $4{\times}2$ PV array, although it can be extended to a number of arrays.

Design and Analysis of Thermoacoustic Refrigerators Using Air as Working Substance

B. G. PRASHANTHA,S. SEETHARAMU,G. S. V. L. NARASIMHAM,M. R. Praveen Kumar 대한설비공학회 2019 International Journal Of Air-Conditioning and Refr Vol.27 No.1

In this paper, the design of 50 W thermoacoustic refrigerators operating with air as working substance at 10 bar pressure and 3% drive ratio for a temperature difference of 28 K is described. The design strategies discussed in this paper help in design and development of low cost thermoacoustic coolers compared to helium as the working substance. The design and optimization of spiral stack and heat exchangers, and the promising 0.2λ and 0.15λ resonator design with taper and divergent section with hemispherical end are discussed. The surface area, volume, length and power density of the hemispherical end design with air as working substance is found better compared to the published 10 and 50 W coolers using helium as the working substance. The theoretical design results are validated using DeltaEC software simulation results. The DeltaEC predicts 51.4% improvement in COP (1.273) at the cold heat exchanger temperature of −2.7∘C with air as working substance for the 50W 0.15λTDH resonator design compared to the published 50W 0.25λTDH resonator design with helium as working substance.

Effect of Stack Spacing on the Performance of Thermoacoustic Refrigerators Using Helium and Air as Working Substances

B. G. PRASHANTHA,S. SEETHARAMU,G. S. V. L. NARASIMHAM,M. R. Praveen Kumar 대한설비공학회 2019 International Journal Of Air-Conditioning and Refr Vol.27 No.2

This paper deals with the design of thermoacoustic refrigerators using linear thermoacoustic theory. The refrigerator components are designed at 3% drive ratio by considering the practical limitations of providing sufficient spacing for attaching the loudspeaker to the resonator tube and accommodating instrumentation. The effects of spiral stack spacing in terms of thermal penetration depth on the theoretical performance of refrigerator using helium and air as working substances are discussed. The quarter-wavelength resonator designs with taper and divergent section terminated with hemispherical end are optimized with helium and air for better performance. Theoretical results are validated with DeltaEC software results and are in agreement with each other. Helium shows better performance compared to air but lacks power density. The DeltaEC predicts COP 0.514 at the cold heat exchanger temperature of −30∘C with helium compared to air (COP 0.616 at8.8∘C) for the 50 W cooling power 100 mm diameter quarter-wavelength resonator designs.

Synthesis and characterization of complex pervoskite BMT ceramics and the effect of gamma radiation at microwave frequency

Ashok K.,Masin B.,Shukla Nishant,Gupta Kinshuk,Gupta Vikas,Ambati Praveen Kumar,Sreemoolanadhan H. 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.1

Ba(Mg 1/3 ,Ta 2/3 )O 3 (BMT), a complex perovskite ceramic with extremely high Q u and that has been the only choice as dielec- tric resonator (DR) for satellite multiplexers extensively used in communication satellites. BMT DRs have been prepared by solid-state route by single-step calcinations followed by fi ring the green compacts at about 1600–1650 °C for 20 h. Excellent Q u -factor > 20,000 at 10 GHz achieved after annealing near 1000 °C combined with near-zero τ f and dielectric constant ( ε r ) ~ 24. The DRs are subjected to 100 kRad and 1MRad γ irradiation exposure. The resonant frequency and Q u are measured after the irradiation and found to be within the range of measurement error. This paper briefl y discusses the BMT process- ing, characterization, the properties and the eff ects of γ -radiation. These BMT DRs are useful for Satellite applications. The ten-pole filters have been assembled and its performance tested and verified.

Design, analysis and experimental investigation of a rotational piezoelectric energy harvester with storage system

Raja V,Umapathy Mangalanathan,Uma Gandhi,Praveen kumar B,Premkumar S 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.11

Energy harvesting from rotational motion has drawn attention over the years to energise low-power wireless sensor networks in a rotating environment. The harvester works efficiently in a small frequency range which has to be similar to the driving frequency. Because of the constraints of size, precision, and the energy harvester’s weight, it is challenging to design it to suit micro applications. To deal with this problem, this paper proposes a rotational piezoelectric energy harvester (RPEH), which generates a voltage output from rotational motion. This design increases the gravitational force acting on the system by increasing the length of the beam, which in turn increases its vibration in a transverse direction. EulerBernoulli’s theory is utilized to derive the mathematical model of the RPEH under rotational motion, and harvester dynamic equations are derived using the electromechanical Lagrange equations. A prototype of RPEH is developed and the exactness of the proposed mathematical model is verified using experimental results and numerical simulation. Maximum power of 43.77 µW is produced at a rotating frequency of 21 Hz (1260 rpm) with an optimum load resistance of 1141.3 kΩ.