针对直流配电网母线电压稳定性问题,设计了一种变增益线性扩张状态观测器(variable gain linear extended state observer,VGLESO),有效地解决了传统高增益线性扩张状态观测器(linear extended state observer extended state observer,...针对直流配电网母线电压稳定性问题,设计了一种变增益线性扩张状态观测器(variable gain linear extended state observer,VGLESO),有效地解决了传统高增益线性扩张状态观测器(linear extended state observer extended state observer,LESO)在运行初始阶段输出存在峰值的问题。在此基础上进一步提出了一种变增益滑模自抗扰控制策略,将其应用到直流配电网AC-DC双向变流器控制系统中的电压外环。变增益滑模自抗扰控制策略在不需要增加额外电流传感器的情况下,就能够实现对系统总扰动的快速跟踪和补偿,有效地抑制了母线电压波动,提高了系统的动态响应。从理论上证明了VGLESO和变增益滑模自抗扰控制策略的稳定性。最后通过MATLAB/Simulink验证了该控制策略的可行性与正确性。展开更多
Two-dimensional Dion–Jacobson(D-J)phase perovskites are prospective photovoltaic and optoelectronic materials.To study their mechanical properties and carrier-lattice interactions,we conduct femtosecond spectroscopic...Two-dimensional Dion–Jacobson(D-J)phase perovskites are prospective photovoltaic and optoelectronic materials.To study their mechanical properties and carrier-lattice interactions,we conduct femtosecond spectroscopic experiments on the films of a D-J perovskite.After optical excitation,a∼33 meV bandgap oscillation is observed in the film by transient absorption spectroscopy.With the help of transient reflection methods,we reveal that the oscillation originates from the transport of coherent longitudinal acoustic phonons through the film.Large bandgap oscillation indicates a strong coupling between carriers and lattice,and significant bandgap modulation by strains in D-J perovskites.展开更多
Mixed halide perovskites(MHPs)are a class of semiconductor materials with great promise for many optoelectronic applications due to their outstanding photophysical properties.Understanding and tailoring the photogener...Mixed halide perovskites(MHPs)are a class of semiconductor materials with great promise for many optoelectronic applications due to their outstanding photophysical properties.Understanding and tailoring the photogenerated carrier dynamics is essential for further improvement of perovskite performance.Herein,we report a study about the carrier transport and interfacial charge transfer dynamics in Br-gradient MAPbI_(3-x)Br_(x) perovskite thin films prepared by surface ion-exchange method.Driven by the bandgap gradient in MAPbI_(3-x)Br_(x) films,the accelerated internal hole transport and enhanced interfacial extraction efficiency were both observed.Meanwhile,the interfacial electron transfer was also found to be evidently facilitated due to the surface modification during post-treatment.Our findings suggest the possibility of simultaneous acceleration of interfacial electron and hole transfer processes in halide perovskite films via surface post-treatment technique,which is of great importance in further improving the power conversion efficiency of perovskite solar cells.展开更多
文摘针对直流配电网母线电压稳定性问题,设计了一种变增益线性扩张状态观测器(variable gain linear extended state observer,VGLESO),有效地解决了传统高增益线性扩张状态观测器(linear extended state observer extended state observer,LESO)在运行初始阶段输出存在峰值的问题。在此基础上进一步提出了一种变增益滑模自抗扰控制策略,将其应用到直流配电网AC-DC双向变流器控制系统中的电压外环。变增益滑模自抗扰控制策略在不需要增加额外电流传感器的情况下,就能够实现对系统总扰动的快速跟踪和补偿,有效地抑制了母线电压波动,提高了系统的动态响应。从理论上证明了VGLESO和变增益滑模自抗扰控制策略的稳定性。最后通过MATLAB/Simulink验证了该控制策略的可行性与正确性。
基金supported by the Ministry of Science and Technology(No.2018YFA0208704)the National Natural Science Foundation of China(No.22173096).
文摘Two-dimensional Dion–Jacobson(D-J)phase perovskites are prospective photovoltaic and optoelectronic materials.To study their mechanical properties and carrier-lattice interactions,we conduct femtosecond spectroscopic experiments on the films of a D-J perovskite.After optical excitation,a∼33 meV bandgap oscillation is observed in the film by transient absorption spectroscopy.With the help of transient reflection methods,we reveal that the oscillation originates from the transport of coherent longitudinal acoustic phonons through the film.Large bandgap oscillation indicates a strong coupling between carriers and lattice,and significant bandgap modulation by strains in D-J perovskites.
基金financial support from the Ministry of Science and Technology of China(No.2018YFA0208704 and No.2016YFA0200602)the National Natural Science Foundation of China(No.21725305)financial support from the National Natural Science Foundation of China(No.21773237)。
文摘Mixed halide perovskites(MHPs)are a class of semiconductor materials with great promise for many optoelectronic applications due to their outstanding photophysical properties.Understanding and tailoring the photogenerated carrier dynamics is essential for further improvement of perovskite performance.Herein,we report a study about the carrier transport and interfacial charge transfer dynamics in Br-gradient MAPbI_(3-x)Br_(x) perovskite thin films prepared by surface ion-exchange method.Driven by the bandgap gradient in MAPbI_(3-x)Br_(x) films,the accelerated internal hole transport and enhanced interfacial extraction efficiency were both observed.Meanwhile,the interfacial electron transfer was also found to be evidently facilitated due to the surface modification during post-treatment.Our findings suggest the possibility of simultaneous acceleration of interfacial electron and hole transfer processes in halide perovskite films via surface post-treatment technique,which is of great importance in further improving the power conversion efficiency of perovskite solar cells.
