As a key link between the DC source and the grid, the L-type grid-connected inverter must have good and stable control performance. In this paper, the current inner loop of L-type inverter is studied and the PR contro...
As a key link between the DC source and the grid, the L-type grid-connected inverter must have good and stable control performance. In this paper, the current inner loop of L-type inverter is studied and the PR controller is designed by analog method and direct digital method. The performance differences between the discretization methods are compared, and the effect of sampling frequency on the discrete error is also analyzed. In the direct numerical method, the law between the controller parameters and the open-loop root trajectory is analyzed, and two sets of PR controllers are designed based on this. Through simulation experiments, it is verified that the PR controller designed by the direct digital method in this paper can achieve smaller overshoot and faster regulation.
This paper focuses on the system stability of grid-forming (GFM) control through passivity criterion. An accuracy small-signal impedance model under dq-frame is established, which is used to analyze the influence of c...
This paper focuses on the system stability of grid-forming (GFM) control through passivity criterion. An accuracy small-signal impedance model under dq-frame is established, which is used to analyze the influence of controller coefficients on system stability by passivity theory. And the inherent characterization for the risk of low-frequency resonance is revealed, indicating that its non-passivity region always exists, regardless of controller coefficients and specific control schemes. Finally, the theoretical analysis is verified by simulation results and the experiment test.
The accomplishment of nanowelding typically requires the input of high energy,possibly causing appreciable damages to the brittle ***,we report an external field(EF,i.e.,light,direct current(DC),and alternating curren...
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The accomplishment of nanowelding typically requires the input of high energy,possibly causing appreciable damages to the brittle ***,we report an external field(EF,i.e.,light,direct current(DC),and alternating current(AC))-strengthened Ostwald nanowelding(ONW)strategy to enable low-temperature nanowelding of Au nanoparticles(NPs)with nanoscale spacing in solution and propose an electron localization mechanism to understand *** reveal that the EF-derived local electrons not only greatly strengthen the dissolution of surface atoms and the reduction of Au3+ions dissolved,but also confine(together with ordered water molecules)the transport of Au^(3+)ions within the ***,the electrochemical Ostwald ripening(OR)process of the Au NPs is actively strengthened,which,along with the local electron-strengthened surface atom diffusion(as a result of the strong electrostatic repulsion created),enables feasible ONW for solution processing of interdigital electrodes(IDEs)from Au NPs and high-performance transparent conductor(TC)from Ag nanowires(NWs).Our low-temperature nanowelding strategy offers an efficient interconnection technique for the processing of functional nanodevices from individual nanomaterials.
Single-element two-dimensional(2D)tellurium(Te)which possesses an unusual quasi-one-dimensional atomic chain structure is a new member in 2D materials family.2D Te possesses high carrier mobility,wide tunable bandgap,...
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Single-element two-dimensional(2D)tellurium(Te)which possesses an unusual quasi-one-dimensional atomic chain structure is a new member in 2D materials family.2D Te possesses high carrier mobility,wide tunable bandgap,strong light-matter interaction,better environmental stability,and strong anisotropy,making Te exhibit tremendous application potential in next-generation electronic and optoelectronic ***,as an emerging 2D material,the research on fundamental property and device application of Te is still in its ***,this review summarizes the most recent research progresses about the new star 2D Te and discusses its future development ***,the structural features,basic physical properties,and various preparation methods of 2D Te are systemically ***,we emphatically summarize the booming development of 2D Te-based electronic and optoelectronic devices including field effect transistors,photodetectors and van der Waals heterostructure ***,the future challenges,opportunities,and development directions of 2D Te-based electronic and optoelectronic devices are prospected.
The Air-Core Pulsed Alternator (APA) is the preferred power supply for electromagnetic launch systems [1]. However, due to the enormous centrifugal force and the electromagnetic impact torque, extremely high demands a...
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ISBN:
(数字)9789038661353
ISBN:
(纸本)9798350352733
The Air-Core Pulsed Alternator (APA) is the preferred power supply for electromagnetic launch systems [1]. However, due to the enormous centrifugal force and the electromagnetic impact torque, extremely high demands are placed on the strength of the rotor structure. In addition, the design speed of APA is usually high, requiring the machine to pass through the first-order critical speed rapidly to avoid the occurrence of resonance. This paper investigated the structural strength and critical speed of the rotor, as these are two of the most common issues considered in the structural design of the rotor of APA, and discussed the design of the main dimensions of the rotor on this basis.
A rotor screen is employed in superconducting machines between field coils and armature windings, which can be made of magnetic or conductive materials. Since superconducting machines have better performances in torqu...
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A rotor screen is employed in superconducting machines between field coils and armature windings, which can be made of magnetic or conductive materials. Since superconducting machines have better performances in torque density, efficiency and weight, detailed analysis of rotor screen is needed for the growing interests in superconducting wind generators. In this paper, the rotor screen of a 12 MW superconducting direct-drive wind generator with an air-cored rotor is discussed based on 2D Finite Element (FE) models, such as electromagnetic performances and mechanical performances.
Along with a growing concern on indoor air quality,it becomes more and more important to take a control and treat on indoor air pollutants,such as formaldehyde,total volatile organic compounds TVOCs,microbial,and part...
Along with a growing concern on indoor air quality,it becomes more and more important to take a control and treat on indoor air pollutants,such as formaldehyde,total volatile organic compounds TVOCs,microbial,and particulate *** this end,our innovative group used corona discharge plasma together with photo-catalytic to treat *** modified photo catalysts were loaded on the electrode surface,and thus treating formaldehyde in an artificial enclosed *** explore the relative purification factors of plasma cooperated with photo-catalytic and their relationships,the catalyst quantity,inlet rate,temperature,humidity and other process variables were changed during experiments.
The active superconducting current controller (SCC) adopts the principle of series voltage compensation, which can be utilized to limit the fault current effectively during fault conditions. This paper presents an imp...
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ISBN:
(纸本)9781467381086
The active superconducting current controller (SCC) adopts the principle of series voltage compensation, which can be utilized to limit the fault current effectively during fault conditions. This paper presents an improved discretization-based decoupled feedback control for series connected converter of SCC. To improve the system dynamics of discretization-based decoupled feedback control, the effect of the control time delay is considered. Furthermore, a linear state feedback loop which considering the output error vectors is added to the control system to achieve the feature of deadbeat. MATLAB simulation is performed to evaluate the performance of the proposed control.
The dc-link current is an important parameter in voltage source inverter (VSI)-fed Interior Permanent Magnet Synchronous Motor (IPMSM) system. On the one hand, the average value of dc-link current reflects the power l...
The dc-link current is an important parameter in voltage source inverter (VSI)-fed Interior Permanent Magnet Synchronous Motor (IPMSM) system. On the one hand, the average value of dc-link current reflects the power level of dc-side and plays a crucial part in system protection, power management and efficiency optimization. On the other hand, using estimation method instead of dc-link current sensor to obtain the value of dc-link current can reduce system cost and increase system reliability. However, in practical application, some non-ideal factors such as digital delay, dead time effect and current sampling error caused by low carrier ratio may affect the accuracy of estimation. Therefore, an accurate dc-link current estimation method for VSI-fed IPMSM drive system with space-vector pulse width modulation (SVPWM) is proposed in this paper. Both simulation and experimental results of proposed estimation method are presented to verify the feasibility and accuracy of the proposed estimation method.
Whether epoxy resin is degraded or not in composite insulators is the most direct criterion to distinguish Decay-like fracture from brittle fracture and normally mechanical fracture. During the actual operation of com...
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