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- 저자 : Madhan (검색결과 27 건)
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Madhan Mohan,Evgeny Tsyplakov,Christian Winter,Harshavardhan Marabathina 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
IGCTs are increasingly becoming the device of choice for high power applications such as HVDC and FACTS with low losses and high reliability. Voltage Source Converters (VSC) with IGCT semiconductors are the choice in high demanding applications with high power and current ratings primarily due to low overall losses and high power handling capability. IGCT circuit typically require a di/dt limiting snubber for the protection of freewheeling diodes from huge current derivatives and so an over voltage limiting mechanism for the protection of IGCTs. This paper presents the performance evaluation of IGCT and its Clamp Circuit in terms of losses, focusing on MMC converter cells for use in high power applications such as HVDC, FACTS. The proposed method is based on look up tables generated for clamp circuit energy dissipation for the different converter switching states and is synchronized with the actual switching transitions. Additionally, the temperature dependency of the reverse recovery current for the freewheeling diode losses also considered. Hence, it yields an accurate, yet computationally efficient method of loss calculation. The results for IGCT based MMC converters are also compared with IGBT based MMC converter to clearly highlight the advantages of one over the other.
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Real-Time Installation of a Smart Energy Meters Using the Long-Range Network
Madhan A.,Shunmugalatha A.,Vigneshwar A. S. 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1
Smart Meters (SMs) are becoming increasingly important in today's world, with their research, design, and installation growing at an accelerating rate. The utilization of smart meters in electrical engineering spans a wide range of tasks, from authentic surveillance to the analysis of load patterns in houses. The usage of wireless communications has aided this progress. However, several issues arise when smart meters are implemented, including range, regions without Web access, etc. Long-Range (LoRa) technologies have excellent coverages and minimal-power apparatus, allowing smart meters to be installed in a variety of locales, namely those lacking Web access. This work aims to improve a smart network based on the Long-Range specifcation, which eliminates the issues that most other wireless technologies have. Electrically Changeable Measuring Devices for Residences Utilizing Long-Range (ECMDRUL) and Gateways for Domestic Energy Meters Networks using LoRa (GDEMNL) have been proposed in this work, allowing the construction of smart networks with an extensive range and reduced utilization. The device output was 2.823 kW, max. 3.087 kW, min. 1.7 kW and total production of 276.2 kWh. The load data was max. 2.823 kW, min. 0.616 kW and Avg. 1.86 kW, with total sum of 125.8 kWh and peak of 132.2 kWh. The data showed positive energy balance. The power consumption of each residence ranged from 2.3 to 6.9 kW, with solar-based generation system of Residence #6 being a viable option.
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Madhan Kumar, Arumugam,Hwan Kwon, Sun,Chul Jung, Hwa,Park, Young Hee,Kim, Hea Jeong,Shin, Kwang Seon American Chemical Society 2014 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.53 No.23
<P>The generation of compact plasma electrolytic oxidation (PEO) coatings with outstanding corrosion resistance is essential for the widespread application of Mg alloys. In the present investigation, PEO ceramic coatings formed at different silicate concentration and oxidation time on AZ31 Mg alloy were studied, and the resultant surface structures of the oxide films were observed using scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis. X-ray photoelectron spectroscopy and thin film-X-ray diffraction analysis of ceramic coatings showed that the surface coating is mainly composed of Mg<SUB>2</SUB>SiO<SUB>4</SUB>, and MgO with different amount based on oxidation time. Further, the potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) measurements were used to characterize corrosion behavior of PEO coated substrates in 3.5% NaCl solution. The results revealed that PEO coatings processed with 0.2 M silicate showed better performance due to its dense and compact coating with fewer structural imperfections in comparison to others.</P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ie404329s'>ACS Electronic Supporting Info</A></P>
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A. Madhan Kumar,S. Fida Hassan,Ahmad A. Sorour,M. Paramsothy,M. Gupta 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.1
Magnesium (Mg) based implant materials are believed to be the perfect candidates for biomedical applications due to theirversatile properties. However, regulating their corrosion/degradation rate in the biological surroundings is still a noteworthytask. Suitable strategies to overcome this task is to wisely select alloy elements with improved corrosion resistanceand mechanical characteristics. An attempt has been made to enhance the corrosion and biocompatibility performance ofmagnesium alloy AZ31 containing carbon nanotubes (CNTs) as reinforcement and evaluate its degradation and invitromineralization performance in physiological medium. Corrosion behavior of AZ31 alloy with CNTs reinforcement wasinvestigated using electrochemical methods, weight loss, and hydrogen evolution in SBF during short and long-term periods. The obtained results revealed that the corrosion resistance of AZ31 alloy enhanced significantly due to the incorporationof CNTs. Hydrogen evolution test and weight loss tests revealed that the presence of CNTs improves the stability of theMg(OH)2 and efficiently regulate the degradation behavior in SBF. Surface characterization after immersion in SBF revealedthe rapid formation of bone-like apatite layer on the surface, validated a good bioactivity of the AZ31 nanocomposite samples.
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Analysis, Design and Control of Two-Level Voltage Source Converters for HVDC Systems
D. Madhan Mohan,Bhim Singh,B. K. Panigrahi 전력전자학회 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.3
The Voltage Source Converter (VSC) is replacing the conventional line commutated current source converters in High Voltage DC (HVDC) transmission systems. The control of a two-level voltage source converter and its design dealt with HVDC systems and various factors such as reactive power, power factor, and harmonics distortion are discussed in detail. Simulation results are given for the two-level converter and designed control is used for bidirectional power flow. The harmonics minimization is taken by extending the 6-pulse VSC to multipulse voltage source converters. The control is also tested and simulated for a 12-pulse voltage source converter to minimize the harmonic distortion in AC currents.
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Wave Energy Harvesting Turbine: Effect of Hub-To-Tip Profile Modification
P. Madhan Kumar,Paresh Halder,Abdus Samad,Shin Hyung Rhee 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.1
The present paper investigates the leading edge (LE) undulations of a Wells turbine blade through numerical analysis. The aspiration for this modification came from humpback whales, which have uneven protrusions at the LE of their pectoral flippers. The flippers help whales to maneuver during swimming. The work is performed by using three-dimensional steady, incompressible Reynolds Averaged Navier-Stokes (RANS) equations with turbulent closer model. The LE of the turbine blades is modified with undulations of three different amplitudes: 1mm, 2.5mm, and 4mm. The results show that the undulation changes the turbine performance. The amplitude 2.5mm gives the peak performance. The comparison between blades with different amplitudes and the reference blade has been discussed throughout this study.
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Wave Energy Harvesting Turbine: Effect of Hub-To-Tip Profile Modification
Kumar, P. Madhan,Halder, Paresh,Samad, Abdus,Rhee, Shin Hyung Korean Society for Fluid machinery 2018 International journal of fluid machinery and syste Vol.11 No.1
The present paper investigates the leading edge (LE) undulations of a Wells turbine blade through numerical analysis. The aspiration for this modification came from humpback whales, which have uneven protrusions at the LE of their pectoral flippers. The flippers help whales to maneuver during swimming. The work is performed by using three-dimensional steady, incompressible Reynolds Averaged Navier-Stokes (RANS) equations with turbulent closer model. The LE of the turbine blades is modified with undulations of three different amplitudes: 1mm, 2.5mm, and 4mm. The results show that the undulation changes the turbine performance. The amplitude 2.5mm gives the peak performance. The comparison between blades with different amplitudes and the reference blade has been discussed throughout this study.
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Analysis. Design and Control of Two-Level Voltage Source Converters for HVDC Systems
Mohan, D. Madhan,Singh, Bhim,Panigrahi, B.K. The Korean Institute of Power Electronics 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.3
The Voltage Source Converter (VSC) is replacing the conventional line commutated current source converters in High Voltage DC (HVDC) transmission systems. The control of a two-level voltage source converter and its design dealt with HVDC systems and various factors such as reactive power, power factor, and harmonics distortion are discussed in detail. Simulation results are given for the two-level converter and designed control is used for bidirectional power flow. The harmonics minimization is taken by extending the 6-pulse VSC to multipulse voltage source converters. The control is also tested and simulated for a 12-pulse voltage source converter to minimize the harmonic distortion in AC currents.
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Kumar, A. Madhan,Babu, R. Suresh,Ramakrishna, Suresh,de Barros, Ana L.F. Elsevier 2017 Synthetic metals Vol.234 No.-
<P><B>Abstract</B></P> <P>A facile approach based on electrochemical polymerization was used to synthesize polypyrrole/CeO<SUB>2</SUB> (PPy/CeO<SUB>2</SUB>) nanocomposite on an AA2024 alloy surface. CeO<SUB>2</SUB> nanoparticles (NPs) embedded in the PPy matrix were observed using FESEM micrographs with EDX analysis. IR and UV–vis spectroscopy were used to characterize the synthesized PPy/CeO<SUB>2</SUB> nanocomposite. The Raman spectra reflected the interactions between the π-conjugated structure of PPy and CeO<SUB>2</SUB> NPs. TGA thermograms revealed improved thermal stability of the synthesized nanocomposite and were used to determine the amount of nano ceria incorporated in the PPy matrix. The electrochemical corrosion behavior of the coated alloys in 0.6M NaCl solution was examined through potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) measurements. From these electrochemical studies, a larger shift of E<SUB>corr</SUB> in the positive direction with a high amount of CeO<SUB>2</SUB> in the nanocomposite was obtained, as well as a maximum corrosion protection efficiency of 99.64% by incorporating 3% of CeO<SUB>2</SUB> NPs in the PPy coatings. EIS studies also confirmed the enhanced corrosion protection behavior of PPy/CeO<SUB>2</SUB> coatings with higher R<SUB>ct</SUB>, R<SUB>f</SUB> and lower CPE<SUB>dl</SUB> values compared to those of pure PPy coatings. The results showed that the PPy coatings with CeO<SUB>2</SUB> nanoparticles can be potential coating materials for the corrosion protection of AA2024 alloys substrates.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Polypyrrole coatings with nanoceria were prepared through electrochemical route. </LI> <LI> Raman studies confirm the interaction between π-conjugated PPy & nano CeO<SUB>2</SUB>. </LI> <LI> TGA reveals improved thermal stability of the synthesized nanocomposite. </LI> <LI> Uniform distribution of nano CeO<SUB>2</SUB> was confirmed by EDX mapping analysis. </LI> <LI> Corrosion test confirms better surface protection of PPy/Ce than pure PPy. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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