Recently, resonant AC/DC converter has been accepted by the industry. However, the efficiency will be decreased at light load. So, a novel topology with critical controlling mode combined with resonant ones is propose...Recently, resonant AC/DC converter has been accepted by the industry. However, the efficiency will be decreased at light load. So, a novel topology with critical controlling mode combined with resonant ones is proposed in this paper. The new topology can correspond to a 90 plus percent of power converting. So,a novel topology of an state of art integrated circuit, which can be used as power management circuit, has been designed based on the above new topology. A simulator which is specifically suitable for the power controller has been founded in this work and it has been used for the simulation of the novel architecture and the proposed integrated circuit.展开更多
DC distribution networks are often employed in isolated power systems like in marine and aeronautical applications. An interesting alternative to DC machines for the supply of DC grids is constituted by a three-phase ...DC distribution networks are often employed in isolated power systems like in marine and aeronautical applications. An interesting alternative to DC machines for the supply of DC grids is constituted by a three-phase alternator feeding an AC/DC rectifier. In this paper, alternative solutions are investigated where the AC alternator is equipped with more （iV） three-phase windings and feeds the DC load through more （N） cascade-connected rectifiers. The advantages of this solution with respect to the conventional three-phase topology are highlighted along with their dependence on the number （N） of the alternator windings. For this purpose, test results are reported and discussed on a prototype generator whose stator coils can be differently connected to obtained one, two, three or four windings. The major benefits （in terms of DC output current quality and field current ripple） are found when passing from the three-phase solution to the dual winding topology; conversely, relatively little advantage is gained by increasing the number of stator windings above two.展开更多
This paper deals with the operation and performance of VSC （voltage source converter） based HVDC （high voltage direct current） interconnecting two extremely weak AC networks, the experience of Caprivilink project....This paper deals with the operation and performance of VSC （voltage source converter） based HVDC （high voltage direct current） interconnecting two extremely weak AC networks, the experience of Caprivilink project. It is shown in the paper that the HVDC converter automatically provides the supreme voltage and frequency stabilizing function when a critical situation is detected, no matter the disturbances appeared in sending end or receiving end AC networks. This supreme voltage and frequency stabilizing function makes it possible to avoid the blackout even if all the generators are tripped under an extra-ordinary worst contingency. By plots of recorded transients, the paper will show how the eventual blackouts are avoided.展开更多
As the size of the electronic system continuously reduces, characteristics of small volume, light weight, high energy it is very important to develop micro power generator, which has density and continuous energy supp...As the size of the electronic system continuously reduces, characteristics of small volume, light weight, high energy it is very important to develop micro power generator, which has density and continuous energy supplying. Vibration energy exists widely in daily environment. Micro vibration power generator can harvest and exchange the vibration energy to the electrical energy. Micro electret power generator is one kind of the power generators for harvesting vibration energy and has been paid much attention by researchers. This paper describes the development and status of micro electret power generators, including electret materials and charging methods, vibration energy harvesting structures and conversion efficiency improvement.展开更多
基金supported by Program for New Century Excellent Talents in University(NCET)(2008)Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality+1 种基金 (PHR(IHLB)) and Beijing Novel Research Star(2005B01)Ministry of Beijing Science and Technology
文摘Recently, resonant AC/DC converter has been accepted by the industry. However, the efficiency will be decreased at light load. So, a novel topology with critical controlling mode combined with resonant ones is proposed in this paper. The new topology can correspond to a 90 plus percent of power converting. So,a novel topology of an state of art integrated circuit, which can be used as power management circuit, has been designed based on the above new topology. A simulator which is specifically suitable for the power controller has been founded in this work and it has been used for the simulation of the novel architecture and the proposed integrated circuit.
文摘DC distribution networks are often employed in isolated power systems like in marine and aeronautical applications. An interesting alternative to DC machines for the supply of DC grids is constituted by a three-phase alternator feeding an AC/DC rectifier. In this paper, alternative solutions are investigated where the AC alternator is equipped with more （iV） three-phase windings and feeds the DC load through more （N） cascade-connected rectifiers. The advantages of this solution with respect to the conventional three-phase topology are highlighted along with their dependence on the number （N） of the alternator windings. For this purpose, test results are reported and discussed on a prototype generator whose stator coils can be differently connected to obtained one, two, three or four windings. The major benefits （in terms of DC output current quality and field current ripple） are found when passing from the three-phase solution to the dual winding topology; conversely, relatively little advantage is gained by increasing the number of stator windings above two.
文摘This paper deals with the operation and performance of VSC （voltage source converter） based HVDC （high voltage direct current） interconnecting two extremely weak AC networks, the experience of Caprivilink project. It is shown in the paper that the HVDC converter automatically provides the supreme voltage and frequency stabilizing function when a critical situation is detected, no matter the disturbances appeared in sending end or receiving end AC networks. This supreme voltage and frequency stabilizing function makes it possible to avoid the blackout even if all the generators are tripped under an extra-ordinary worst contingency. By plots of recorded transients, the paper will show how the eventual blackouts are avoided.
基金supported by the National Basic Research Program of China ("973" Program) (Grant No. 2009CB320300)
文摘As the size of the electronic system continuously reduces, characteristics of small volume, light weight, high energy it is very important to develop micro power generator, which has density and continuous energy supplying. Vibration energy exists widely in daily environment. Micro vibration power generator can harvest and exchange the vibration energy to the electrical energy. Micro electret power generator is one kind of the power generators for harvesting vibration energy and has been paid much attention by researchers. This paper describes the development and status of micro electret power generators, including electret materials and charging methods, vibration energy harvesting structures and conversion efficiency improvement.
