Step-up Switched Capacitor Multilevel Inverter with a Cascaded Structure in Asymmetric DC Source Configuration

Roy, Tapas,Bhattacharjee, Bidrohi,Sadhu, Pradip Kumar,Dasgupta, Abhijit,Mohapatra, Srikanta The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4

This study presents a novel step-up switched capacitor multilevel inverter (SCMLI) structure. The proposed structure comprises 2 unequal DC voltage sources, 4 capacitors, and 14 unidirectional power switches. It can synthesize 21 output voltage levels. The important features of the proposed topology are its self-voltage boosting and inherent capacitor voltage balancing capabilities. Furthermore, a cascaded structure of the proposed SCMLI with an asymmetric DC voltage source configuration is presented. The proposed topology and its cascaded structure are compared with conventional and other recently developed topologies in terms of different aspects, such as the required components to produce a specific number of output voltage levels, the total standing voltage (TSV) and peak inverse voltage of the structure, and the maximum number of switches in the conducting path. Furthermore, a cost function is developed to verify the cost-effectiveness of the proposed topology with respect to other topologies. The TSV of the proposed topology is significantly lower than those of other topologies. Moreover, the developed topology is cost-effective compared with other topologies. A detailed operating principle, power loss analysis, and selection procedure for switched capacitors are presented for the proposed SCMLI structure. Extensive simulation and experimental studies of a 21-level inverter structure prove the effectiveness and merits of the proposed SCMLI.

A New Single Phase Multilevel Inverter Topology with Two-step Voltage Boosting Capability

Roy, Tapas,Sadhu, Pradip Kumar,Dasgupta, Abhijit The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.5

In this paper, a new single phase multilevel inverter topology with a single DC source is presented. The proposed topology is developed based on the concepts of the L-Z source inverter and the switched capacitor multilevel inverter. The input voltage to the proposed inverter is boosted by two steps: the first step by an impedance network and the second step by switched capacitor units. Compared to other existing topologies, the presented topology can produce a higher boosted multilevel output voltage while using a smaller number of components. In addition, it provides more flexibility to control boosting factor, size, cost and complexity of the inverter. The proposed inverter possesses all the advantages of the L-Z source inverter and the switched capacitor multilevel inverter like controlling the start-up inrush current and capacitor voltage balancing using a simple switching strategy. The operating principle and general expression for the different parameters of the proposed topology are presented in detail. A phase disposition pulse width modulation strategy has been developed to switch the inverter. The effectiveness of the topology is verified by extensive simulation and experimental studies on a 7-level inverter structure.

Non-exhaust particulate pollution in Asian countries: A comprehensive review of sources, composition, and health effects

Anamika Roy,Mamun Mandal,Sujit Das,Manoj Kumar,Robert Popek,Amit Awasthi,Balendu Shekher Giri,Kartick Chandra Mondal,Abhijit Sarkar 대한환경공학회 2023 Environmental Engineering Research Vol.29 No.3

Recent regulations on exhaust emissions have led to an increase in non-exhaust emissions, which now surpasses exhaust emissions. Non-exhaust emissions are mainly generated from brake and tire particle abrasion, road wear, and re-suspended road dust. In Asia, non-exhaust emissions have increased significantly over the past 50 years, resulting in almost 92% of the population breathing polluted air, which accounts for 70% of air pollution related-deaths. Most Asian countries with poor air quality are developing or underdeveloped. Taking this into consideration, the current study aims to shed light on particulate pollution from non-exhaust emissions in the Asian context to assess the current status and its health consequences and provides technological solutions. The study is based on an in-depth analysis of existing reviews and research concerning non-exhaust emissions and their health impacts in Asia to pinpoint knowledge gaps. The study found that particulate pollutants had exceeded WHOs standards in many Asian countries, bringing deleterious health consequences among children and the elderly. The findings underscore the significance of future researchers efforts to devise solutions that curtail non-exhaust emissions, ultimately reducing air pollution, augmenting air quality, fostering better health outcomes, and paving way for a more sustainable future before it is too late.

A New Single Phase Multilevel Inverter Topology with Two-step Voltage Boosting Capability

Tapas Roy,Pradip Kumar Sadhu,Abhijit Dasgupta 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.5

In this paper, a new single phase multilevel inverter topology with a single DC source is presented. The proposed topology is developed based on the concepts of the L-Z source inverter and the switched capacitor multilevel inverter. The input voltage to the proposed inverter is boosted by two steps: the first step by an impedance network and the second step by switched capacitor units. Compared to other existing topologies, the presented topology can produce a higher boosted multilevel output voltage while using a smaller number of components. In addition, it provides more flexibility to control boosting factor, size, cost and complexity of the inverter. The proposed inverter possesses all the advantages of the L-Z source inverter and the switched capacitor multilevel inverter like controlling the start-up inrush current and capacitor voltage balancing using a simple switching strategy. The operating principle and general expression for the different parameters of the proposed topology are presented in detail. A phase disposition pulse width modulation strategy has been developed to switch the inverter. The effectiveness of the topology is verified by extensive simulation and experimental studies on a 7-level inverter structure.

Comparative Study of P-aramid Based Soft and Stiff Composite Panels for Protective Application

Rupayan Roy,Abhijit Majumdar,Bhupendra Singh Butola 한국섬유공학회 2019 Fibers and polymers Vol.20 No.2

In this research work, the authors investigated the impact behaviour of Kevlar based flexible and stiff composites. These composites were prepared by using natural rubber latex (NR) and epoxy resin respectively as matrix and p-aramid (Kevlar 129) fabric as reinforcement. For flexible composites, the ratio of reinforcement and matrix was 90:10, and for stiff composites, the ratio was 40:60. In both the cases, two layers of Kevlar fabric were used. Stitched fabric panels consisting of two layers of Kevlar were used as control. It was observed that the flexible composites exhibited 2.8 times higher puncture force whereas for stiff composites the value was 6.6 times in comparison to only stitched panels. In terms of impact energy absorption, flexible composites showed 73 % higher value as compared to the stitched panels whereas for stiff composites, 86 % reduction was witnessed.

Step-up Switched Capacitor Multilevel Inverter with a Cascaded Structure in Asymmetric DC Source Configuration

Tapas Roy,Bidrohi Bhattacharjee,Pradip Kumar Sadhu,Abhijit Dasgupta,Srikanta Mohapatra 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4

This study presents a novel step-up switched capacitor multilevel inverter (SCMLI) structure. The proposed structure comprises 2 unequal DC voltage sources, 4 capacitors, and 14 unidirectional power switches. It can synthesize 21 output voltage levels. The important features of the proposed topology are its self-voltage boosting and inherent capacitor voltage balancing capabilities. Furthermore, a cascaded structure of the proposed SCMLI with an asymmetric DC voltage source configuration is presented. The proposed topology and its cascaded structure are compared with conventional and other recently developed topologies in terms of different aspects, such as the required components to produce a specific number of output voltage levels, the total standing voltage (TSV) and peak inverse voltage of the structure, and the maximum number of switches in the conducting path. Furthermore, a cost function is developed to verify the cost-effectiveness of the proposed topology with respect to other topologies. The TSV of the proposed topology is significantly lower than those of other topologies. Moreover, the developed topology is cost-effective compared with other topologies. A detailed operating principle, power loss analysis, and selection procedure for switched capacitors are presented for the proposed SCMLI structure. Extensive simulation and experimental studies of a 21-level inverter structure prove the effectiveness and merits of the proposed SCMLI.

Understanding the Effects of Surface Finish on Diffusion Bonding of AZ31 Alloys

Matthew Criado,Abhijit Roy,John Ohodnicki,Nicholas Tondravi,Hannah Fischer,Alejandro Almarza,Howard A. Kuhn,Prashant N. Kumta 대한용접접합학회 2023 대한용접·접합학회지 Vol.41 No.5

Methods to optimize the diffusion bonding (DB) process while also creating lap joints were investigated using AZ31, the commercial Mg alloy, focusing primarily on studying the effects of varying conventional process parameters and more importantly, exploring the influence of surface roughness on creating an acceptable strong bond. The results indicate that when contact is made between surface areas of roughness (Ra > 0.2 ㎛) diffusion is facilitated at reduced process parameters of time and temperature. Furthermore, this early bond initiation combined with the optimized DB process parameters results in a stronger bond with strengths increasing by ~ 150% in comparison to the DB samples created with a smooth surface finish. Additionally, less than 20% total overall distortion is observed while preserving a uniform microstructure of consistent grain sizes in the material over the entire joining region compared with the parent material.

Assessment of toxicity and genotoxic safety profile of novel fisetin ruthenium-p-cymene complex in mice

Seal Ishita,Sil Sidhanta,Das Abhijit,Roy Souvik 한국독성학회 2023 Toxicological Research Vol.39 No.2

Throughout the last decades flavonoids have been considered as a powerful bioactive molecule. Complexation of these flavonoids with metal ions demonstrated the genesis of unique organometallic complexes which provide improved pharmacological and therapeutic activities. In this research, the fisetin ruthenium-p-cymene complex was synthesized and characterized via different analytical methods like UV–visible spectroscopy, Fourier-transform infrared spectroscopy, mass spectroscopy, and scanning electron microscope. The toxicological profile of the complex was evaluated by acute and sub-acute toxicity. Additionally, the mutagenic and genotoxic activity of the complex was assessed by Ames test, chromosomal aberration test, and micronucleus based assay in Swiss albino mice. The acute oral toxicity study exhibited the LD50 of the complex at 500 mg/ kg and subsequently, the sub-acute doses were selected. In sub-acute toxicity study, the hematology and serum biochemistry of the 400 mg/kg group showed upregulated white blood cells, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, creatinine, glucose and cholesterol. However, there was no treatment related alteration of hematological and serum biochemical parameters in the 50, 100, and 200 mg/kg group. In the histopathological analysis, the 50, 100, and 200 mg/kg groups were not associated with any toxicological alterations, whereas the 400 mg/kg group showed prominent toxicological incidences. Nevertheless, the treatment with fisetin ruthenium-p-cymene complex did not exhibit any mutagenic and genotoxic effect in Swiss albino mice. Thus, the safe dose of this novel organometallic complex was determined as 50, 100, and 200 mg/kg without any toxicological and genotoxic potential.