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Chokkalingam, Bharatiraja,Bhaskar, Mahajan Sagar,Padmanaban, Sanjeevikumar,Ramachandaramurthy, Vigna K.,Iqbal, Atif The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.3
Multilevel Inverters (MLIs) are widely used in medium voltage applications due to their various advantages. In addition, there are numerous types of MLIs for such applications. However, the diode-less 3-level (3L) T-type Neutral Point Clamped (NPC) MLI is the most advantageous due to its low conduction losses and high potential efficiency. The power circuit of a 3L T-type NPC is derived by the conventional two level inverter by a slight modification. In order to explore the MLI performance for various Pulse Width Modulation (PWM) schemes, this paper examines the operation of a 3L (five level line to line) T-type NPC MLI for various types of Multi-Carriers Pulse Width Modulation (MCPWM) schemes. These PWM schemes are compared in terms of their voltage profile, total harmonic distortion (THD) and conduction losses. In addition, a 3L T-type NPC MLI is also compared with the conventional NPC in terms of number of switches, clamping diodes, main diodes and capacitors. Moreover, the capacitor-balancing problem is also investigated using the Neutral Point Fluctuation (NPF) method with all of the MCPWM schemes. A 1kW 3L T-type NPC MLI is simulated in MATLAB/Simulink and implemented experimentally and its performance is tested with a 1HP induction motor. The results indicate that the 3L T-type NPC MLI has better performance than conventional NPC MLIs.
Bharatiraja Chokkalingam,Mahajan Sagar Bhaskar,Sanjeevikumar Padmanaban,Vigna K. Ramachandaramurthy,Atif Iqbal 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.3
Multilevel Inverters (MLIs) are widely used in medium voltage applications due to their various advantages. In addition, there are numerous types of MLIs for such applications. However, the diode-less 3-level (3L) T-type Neutral Point Clamped (NPC) MLI is the most advantageous due to its low conduction losses and high potential efficiency. The power circuit of a 3L T-type NPC is derived by the conventional two level inverter by a slight modification. In order to explore the MLI performance for various Pulse Width Modulation (PWM) schemes, this paper examines the operation of a 3L (five level line to line) T-type NPC MLI for various types of Multi-Carriers Pulse Width Modulation (MCPWM) schemes. These PWM schemes are compared in terms of their voltage profile, total harmonic distortion (THD) and conduction losses. In addition, a 3L T-type NPC MLI is also compared with the conventional NPC in terms of number of switches, clamping diodes, main diodes and capacitors. Moreover, the capacitor-balancing problem is also investigated using the Neutral Point Fluctuation (NPF) method with all of the MCPWM schemes. A 1kW 3L T-type NPC MLI is simulated in MATLAB/Simulink and implemented experimentally and its performance is tested with a 1HP induction motor. The results indicate that the 3L T-type NPC MLI has better performance than conventional NPC MLIs.
The isopropylation of biphenyl over H-mordenite - Roles of 3- and 4-isopropylbiphenyls
Yoshihiro Sugi,Chokkalingam Anand,Tomonori Sugimura,Kenichi Komura,Yoshihiro Kubota,Jong Ho Kim,Gon Seo,Ajayan Vinu 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.5
The isopropylation of biphenyl (BP) and 3- and 4-isopropylbiphenyls (3- and 4-IPBPs) was examined over H-mordenites (MOR) to elucidate the mechanism of shape-selective formation of 4,4'-diisopropylbiphenyl (4,4'-DIPB). The isopropylation of BP occurred predominantly to form 4-isopropylbiphenyl (4-IPBP) from BP and 4,4'-DIPB from 4-IPBP. However, 3-IPBP, a minor isomer from BP, cannot participate effectively in the formation of 3,4'-DIPB due to steric restriction of its isopropyl moiety with MOR channels. Selective formation of 4,4'-DIPB was observed at low to moderate temperatures: 225-275 oC. However, the selectivities for 4,4'-DIPB were decreased at high temperatures,300-350 oC under propene pressure, 0.8MPa, by the isomerization of 4,4'-DIPB at external acid sites. The isomerization of 4,4'-DIPB occurred under low propene pressure even at 250 oC. The roles of 3- and 4-IPBPs in the formation of DIPB isomers were examined in the isopropylation of their mixtures. 4-IPBP was consumed much faster than 3-IPBP in all cases examined. 4-IPBP was an exclusive precursor to DIPB isomers, particularly 4,4'-DIPB. 4,4'-DIPB was also found as a predominant isomer in encapsulated products at all conditions examined. These results show that 4-IPBP can preferentially establish active transition state with propene and acid site in MOR channels, resulting in selective formation of 4,4'-DIPB. It is concluded that the isopropylation of BP over MOR occurs through reactant selectivity mechanism and restricted transition state mechanism, but not through product selectivity mechanism.
Task scheduling in heterogeneous cloud environment using mean grey wolf optimization algorithm
Gobalakrishnan Natesan,Arun Chokkalingam 한국통신학회 2019 ICT Express Vol.5 No.2
The primary objective of task scheduling involves scheduling the task on resources and minimizing the objective of the schedule. In this study, we proposed mean grey wolf optimization algorithm to enhance the system performance there by depleting the scheduling issues. The main objective of this method is minimizing the makespan and energy consumption. The objective of the proposed algorithms has been evaluated using CloudSim toolkit for standard workload (left-skewed & right-skewed). The outcome of the simulation result shows that the proposed Mean GWO algorithm renders comparatively ample result than the other existing algorithms.
Design of a Novel Boomerang Trajectory for Sliding Mode Controller
Kamalesh MS,Senthilnathan Nattuthurai,Bharatiraja Chokkalingam 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.11
Sliding Mode Controllers (SMC) is widely known for its robustness and controllability for a non-linear system during transient conditions. The main advantage of SMC is that of sliding a control variable along the trajectory and converges to zero or nearest to zero and make the system to attain a stable condition. Various methodologies and approaches like discontinuous controllers, second-order sliding modes, twisting algorithms, etc. are available for the SMC implementation. However, every algorithm is facing the problem of convergence and error tracking in a finite amount of time. The primary purpose of this paper is to formulate and design an SMC with a new trajectory which overcomes the drawback of the existing methodologies. This paper proposes a novel boomerang trajectory, which omits the reaching phase and follows a semi-elliptical and semi-circular path for a quick convergence. SMC with boomerang trajectory is analyzed for its stability at transient conditions, and the results show significant improvement in terms of convergence time when compared to the existing trajectories and also it is asymptotically stable. The entire system is simulated in Matlab / Simulink and the same prototypical setup has been designed, and implemented for evaluation purpose using dSPACE-MicroLabBox-ACE-DS1202 platform.
Kim, Chun-Gon,Kang, Jong-Pyo,Huo, Yue,Chokkalingam, Mohan,Kim, Yeon-Ju,Kim, Dong-Hyun,Yang, Deok-Chun Springer-Verlag 2018 Archives of microbiology Vol.200 No.7
<P>A novel bacterium, designated DCY114(T), was isolated from ginseng-cultivated soil in Gochang-gun, Republic of Korea. This isolate was assigned to the genus Paenibacillus and is closely related to Paenibacillus amylolyticus NRRL NRS-290(T) (98.3%), P. dongdonensis KUDC0114(T) (98.0%), P. tylopili MK2(T) (97.9%), P. tundrae A10b(T) (97.8%), and P. xylanexedens B22a(T) (97.5%) based on 16S rRNA gene sequence analysis. Strain DCY114(T) is a Gram-reaction positive, catalase and oxidase positive, facultatively aerobic rod that is motile by peritrichous flagella. Strain DCY114(T) produces siderophores and indole-3-acetic acid (IAA) and is able to solubilize phosphate as a plant growth-promoting bacterium. MK-7 was the diagnostic menaquinone. The major cellular fatty acids were anteiso-C-15:0, C-16:0, and C-18:0, and the major polar lipids were diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), and an unknown amino lipid (AL1,2). The genomic DNA G + C content was 46.0 mol%. Phenotypic and chemotaxonomic results also placed strain DCY114(T) within the genus Paenibacillus. DNA-DNA homology values between strain DCY114(T) and closely related reference strains were lower than 43%. The low DNA relatedness data in combination with phylogenetic and biochemical tests indicated that strain DCY114(T) could not be assigned to a recognized species. The results of this study support that the DCY114(T) strain is a novel species belonging to the genus Paenibacillus, for which the name Paenibacillus panacihumi is proposed. The type strain is DCY114(T) (= KCTC 33915(T) = JCM 32073(T)).</P>