Variations in the behavior of power supplies caused electrical behavior dependence with environmental conditions. by environmental conditions require accurate characterization of the This paper introduces models to he...Variations in the behavior of power supplies caused electrical behavior dependence with environmental conditions. by environmental conditions require accurate characterization of the This paper introduces models to help predict relative humidity （Rtt） and other environmental factors influence on sensitive circuitry in power electronic systems. The resistivity and permittivity of an insulator have been modeled using different water contents i.e. RH, such model also included the mechanical properties of the design. An application example of a high power density, high voltage DC-DC converter is used to verify the results.展开更多
International standards impose several constraints concerning the electric power quality and require that the harmonic content of the line current of grid connected equipment is below assigned limits; for this reason,...International standards impose several constraints concerning the electric power quality and require that the harmonic content of the line current of grid connected equipment is below assigned limits; for this reason, operating of AC-DC converters with high power factor and low line current distortion has become essential. In this paper, the prototypal realization of a three-phase AC-DC 48 V power electronic converter for telecom system supplying is described and experimental testing results are discussed. The main constraints in the power supply design are the required power density of about 900 W per dm3 as well as the absence of the neutral wire in the supply grid. The carried out investigation is focused on three-level power converter configurations which are considered in order to reduce voltage rating of power switches. As a result of the reduced voltage, low on-resistance metal-oxide-semiconductor field effect transistors can be used in the power stage, solution which allows to achieve improved efficiency as well as increased switching frequency with respect to the insulated gate bipolar transistors based two-level topologies.展开更多
The current need to fasten the implementation of renewable energies greatly depends on the development of competitive storage devices, and while there is not a single technology which is likely capable to competitivel...The current need to fasten the implementation of renewable energies greatly depends on the development of competitive storage devices, and while there is not a single technology which is likely capable to competitively cover the wide range of possible demands, electrochemical technologies are one of the most promising for many of them. For the realization of this promise, new materials fulfilling criteria such as high energy density, high power density, competitive cost, reliability, and environmental compatibility need to be developed in the near future. Electrochemical energy storage devices can be classified into two main technologies： supercapacitors and batteries （including redox flow batteries）. Materials and applications for these technologies are discussed and compared, listing current status, technical and strategic challenges.展开更多
Cooling is very important for the safe operation of an electron cyclotron resonance ion source(ECRIS),especially when the window current density is very high(up to 11 A/mm2).We proposed an innovative cooling method us...Cooling is very important for the safe operation of an electron cyclotron resonance ion source(ECRIS),especially when the window current density is very high(up to 11 A/mm2).We proposed an innovative cooling method using evaporative cooling technology.A demonstration prototype was designed,built and tested.The on-site test results showed that the temperature of the solenoids and permanent magnets maintains well in the normal operational range of 14–18 GHz.A simple computational model was developed to predict the characteristics of the two-phase flow.The predicted temperatures agreed well with the on-site test data within 2 K.We also proposed useful design criteria.The successful operation of the system indicates the potential for broad application of evaporative cooling technology in situations in which the power intensity is very high.展开更多
文摘Variations in the behavior of power supplies caused electrical behavior dependence with environmental conditions. by environmental conditions require accurate characterization of the This paper introduces models to help predict relative humidity （Rtt） and other environmental factors influence on sensitive circuitry in power electronic systems. The resistivity and permittivity of an insulator have been modeled using different water contents i.e. RH, such model also included the mechanical properties of the design. An application example of a high power density, high voltage DC-DC converter is used to verify the results.
文摘International standards impose several constraints concerning the electric power quality and require that the harmonic content of the line current of grid connected equipment is below assigned limits; for this reason, operating of AC-DC converters with high power factor and low line current distortion has become essential. In this paper, the prototypal realization of a three-phase AC-DC 48 V power electronic converter for telecom system supplying is described and experimental testing results are discussed. The main constraints in the power supply design are the required power density of about 900 W per dm3 as well as the absence of the neutral wire in the supply grid. The carried out investigation is focused on three-level power converter configurations which are considered in order to reduce voltage rating of power switches. As a result of the reduced voltage, low on-resistance metal-oxide-semiconductor field effect transistors can be used in the power stage, solution which allows to achieve improved efficiency as well as increased switching frequency with respect to the insulated gate bipolar transistors based two-level topologies.
文摘The current need to fasten the implementation of renewable energies greatly depends on the development of competitive storage devices, and while there is not a single technology which is likely capable to competitively cover the wide range of possible demands, electrochemical technologies are one of the most promising for many of them. For the realization of this promise, new materials fulfilling criteria such as high energy density, high power density, competitive cost, reliability, and environmental compatibility need to be developed in the near future. Electrochemical energy storage devices can be classified into two main technologies： supercapacitors and batteries （including redox flow batteries）. Materials and applications for these technologies are discussed and compared, listing current status, technical and strategic challenges.
基金supported by the Open Research Project of the Major Science and Technology Infrastructure in the Chinese Academy of Sciences-Application of Evaporative Cooling Technology in the Field of Accelerator
文摘Cooling is very important for the safe operation of an electron cyclotron resonance ion source(ECRIS),especially when the window current density is very high(up to 11 A/mm2).We proposed an innovative cooling method using evaporative cooling technology.A demonstration prototype was designed,built and tested.The on-site test results showed that the temperature of the solenoids and permanent magnets maintains well in the normal operational range of 14–18 GHz.A simple computational model was developed to predict the characteristics of the two-phase flow.The predicted temperatures agreed well with the on-site test data within 2 K.We also proposed useful design criteria.The successful operation of the system indicates the potential for broad application of evaporative cooling technology in situations in which the power intensity is very high.
