Research on flexible or wearable electronics has been grown remarkably due to the advent of nanomaterials,such as metal nanowires,graphene,or transition metal dichalcogenides.Although each nanomaterial has mechanical ...Research on flexible or wearable electronics has been grown remarkably due to the advent of nanomaterials,such as metal nanowires,graphene,or transition metal dichalcogenides.Although each nanomaterial has mechanical and electrical characteristics that can be applied into flexible electronics,the limitations of each nanomaterial are also clear.In order to overcome the limitations of these nanomaterials,research on the hybrid structures of nanomaterials has been extensively conducted.In this study,we introduce the properties of one-dimensional nanomaterials,twodimensional nanomaterials,and their hybrid nanomaterials.And then,we provide information concerning various flexible electronics based on these nanomaterials.展开更多
The concept of a flexible power electronics substation(FPES)was first applied in the Zhangbei DC distribution network demonstration project.As a multi-port power electronics transformer(PET)with different AC and DC vo...The concept of a flexible power electronics substation(FPES)was first applied in the Zhangbei DC distribution network demonstration project.As a multi-port power electronics transformer(PET)with different AC and DC voltage levels,the FPES has adopted a novel topology integrating modular multilevel converter(MMC)and four-winding medium frequency transformer(FWMFT)based multiport DC-DC converter,which can significantly reduce capacitance in each sub-module(SM)of a MMC and also save space and cost.In this paper,in order to accelerate speed of electromagnetic transient(EMT)simulations of FPES based hybrid AC/DC distribution systems,an averaged-value model(AVM)is proposed for efficient and accurate representation of FPES.Assume that all SM capacitor voltages are perfectly balanced in the MMC,then the MMC behavior can be modeled using controlled voltage sources based on modulation voltages from control systems.In terms of the averaged current transfer characteristics among the windings of the FWMFT,we consider that all multiport DC-DC converters are controlled with the same dynamics,a lumped averaged model using controlled current and voltage sources has been developed for these four-port DC-DC converters connected to the upper or lower arms of the MMC.The presented FPES AVM model has been tested and validated by comparison with a detailed IGBT-based EMT model.Results show that the AVM is significantly more efficient while maintaining its accuracy in an EMT simulation.展开更多
基金Bio&Medical Technology Development Program,Grant/Award Number:2018M3A9F1021649Industrial Technology Innovation Program,Grant/Award Number:10080577+3 种基金Institute for Basic Science,Grant/Award Number:IBS-R026-D1Ministry of Science&ICT(MSIT)and the Ministry of Trade,Industry and Energy(MOTIE)of Korea through the National Research Foundation,Grant/Award Numbers:2016R1A5A1009926,2019R1A2B5B03069358Nano Material Technology Development Program,Grant/Award Numbers:2015M3A7B4050308,2016M3A7B4910635Research Program funded by Yonsei University,Grant/Award Number:2018-22-0194。
文摘Research on flexible or wearable electronics has been grown remarkably due to the advent of nanomaterials,such as metal nanowires,graphene,or transition metal dichalcogenides.Although each nanomaterial has mechanical and electrical characteristics that can be applied into flexible electronics,the limitations of each nanomaterial are also clear.In order to overcome the limitations of these nanomaterials,research on the hybrid structures of nanomaterials has been extensively conducted.In this study,we introduce the properties of one-dimensional nanomaterials,twodimensional nanomaterials,and their hybrid nanomaterials.And then,we provide information concerning various flexible electronics based on these nanomaterials.
基金This work was supported in part by the National Nature Science Foundation of China(51977142)。
文摘The concept of a flexible power electronics substation(FPES)was first applied in the Zhangbei DC distribution network demonstration project.As a multi-port power electronics transformer(PET)with different AC and DC voltage levels,the FPES has adopted a novel topology integrating modular multilevel converter(MMC)and four-winding medium frequency transformer(FWMFT)based multiport DC-DC converter,which can significantly reduce capacitance in each sub-module(SM)of a MMC and also save space and cost.In this paper,in order to accelerate speed of electromagnetic transient(EMT)simulations of FPES based hybrid AC/DC distribution systems,an averaged-value model(AVM)is proposed for efficient and accurate representation of FPES.Assume that all SM capacitor voltages are perfectly balanced in the MMC,then the MMC behavior can be modeled using controlled voltage sources based on modulation voltages from control systems.In terms of the averaged current transfer characteristics among the windings of the FWMFT,we consider that all multiport DC-DC converters are controlled with the same dynamics,a lumped averaged model using controlled current and voltage sources has been developed for these four-port DC-DC converters connected to the upper or lower arms of the MMC.The presented FPES AVM model has been tested and validated by comparison with a detailed IGBT-based EMT model.Results show that the AVM is significantly more efficient while maintaining its accuracy in an EMT simulation.
