In this paper, a new inverter topology dedicated to isolated or grid-connected PV systems is proposed. This inverter is based on the structures of a stacked multi-cell converter (SMC) and an H-bridge. This new topolog...In this paper, a new inverter topology dedicated to isolated or grid-connected PV systems is proposed. This inverter is based on the structures of a stacked multi-cell converter (SMC) and an H-bridge. This new topology has allowed the voltage stresses of the converter to be distributed among several switching cells. Secondly, divide the input voltage into several fractions to reduce the number of power semiconductors to be switched. In this contribution, the general topology of this micro-inverter has been described and the simulation tests developed to validate its operation have been presented. Finally, we discussed the simulation results, the efficiency of this topology and the feasibility of its use in a grid-connected photovoltaic production system.展开更多
Micro-thermal conductivity detector(μTCD)gas sensors work by detecting changes in the thermal conductivity of the surrounding medium and are used as detectors in many applications such as gas chromatography systems.C...Micro-thermal conductivity detector(μTCD)gas sensors work by detecting changes in the thermal conductivity of the surrounding medium and are used as detectors in many applications such as gas chromatography systems.Conventional TCDs use steady-state resistance(i.e.,temperature)measurements of a micro-heater.In this work,we developed a new measurement method and hardware configuration based on the processing of the transient response of a low thermal mass TCD to an electric current step.The method was implemented for a 100-μm-long and 1-μm-thick micro-fabricated bridge that consisted of doped polysilicon conductive film passivated with a 200-nm silicon nitride layer.Transient resistance variations of theμTCD in response to a square current pulse were studied in multiple mixtures of dilute gases in nitrogen.Simulations and experimental results are presented and compared for the time resolved and steady-state regime of the sensor response.Thermal analysis and simulation show that the sensor response is exponential in the transient state,that the time constant of this exponential variation was a linear function of the thermal conductivity of the gas ambient,and that the sensor was able to quantify the mixture composition.The level of detection in nitrogen was estimated to be from 25 ppm for helium to 178 ppm for carbon dioxide.With this novel approach,the sensor requires approximately 3.6 nJ for a single measurement and needs only 300μs of sampling time.This is less than the energy and time required for steady-state DC measurements.展开更多
文摘In this paper, a new inverter topology dedicated to isolated or grid-connected PV systems is proposed. This inverter is based on the structures of a stacked multi-cell converter (SMC) and an H-bridge. This new topology has allowed the voltage stresses of the converter to be distributed among several switching cells. Secondly, divide the input voltage into several fractions to reduce the number of power semiconductors to be switched. In this contribution, the general topology of this micro-inverter has been described and the simulation tests developed to validate its operation have been presented. Finally, we discussed the simulation results, the efficiency of this topology and the feasibility of its use in a grid-connected photovoltaic production system.
基金The sensor that was tested in this work is based on the patents:No.7,911,010,No.8,426,932 and No.8,884,382.
文摘Micro-thermal conductivity detector(μTCD)gas sensors work by detecting changes in the thermal conductivity of the surrounding medium and are used as detectors in many applications such as gas chromatography systems.Conventional TCDs use steady-state resistance(i.e.,temperature)measurements of a micro-heater.In this work,we developed a new measurement method and hardware configuration based on the processing of the transient response of a low thermal mass TCD to an electric current step.The method was implemented for a 100-μm-long and 1-μm-thick micro-fabricated bridge that consisted of doped polysilicon conductive film passivated with a 200-nm silicon nitride layer.Transient resistance variations of theμTCD in response to a square current pulse were studied in multiple mixtures of dilute gases in nitrogen.Simulations and experimental results are presented and compared for the time resolved and steady-state regime of the sensor response.Thermal analysis and simulation show that the sensor response is exponential in the transient state,that the time constant of this exponential variation was a linear function of the thermal conductivity of the gas ambient,and that the sensor was able to quantify the mixture composition.The level of detection in nitrogen was estimated to be from 25 ppm for helium to 178 ppm for carbon dioxide.With this novel approach,the sensor requires approximately 3.6 nJ for a single measurement and needs only 300μs of sampling time.This is less than the energy and time required for steady-state DC measurements.
