Waveform control method was commonly adopted to reduce the spatter of CO2 arc welding and improve the weld formation. It certainly would reduce the self-regulation ability of arc due to the adoption of segmented const...Waveform control method was commonly adopted to reduce the spatter of CO2 arc welding and improve the weld formation. It certainly would reduce the self-regulation ability of arc due to the adoption of segmented constant current control which especially led to arc＂ blowout with the abrupt change oat＂ arc＂ length or downward welding. Therefore alterative wire-feed system based on arc voltage negative feedback was put forward to improve the .stability of arc＂ length in this paper. Double closed-loop and double fuzzy P1 regulation were adopted in this system. Fuzzy control of induced voltage was adopted in the inner-loop which improved the stability and fast response of wire-feed system. Fuzz）＂ control of arc＂ voltage negative feedback was used in the outer-loop whose output .served as the input of negative feedback regulation of inner-loop induced voltage. This method could remain arc＂ length and weld penetration unchan, ged on the basils of reducing spatter and improving formation and it was proved by downward welding tests.展开更多
A fully differential R-MOSFET-C fourth-order Bessel active lowpass filter employing fully differential operational amplifier,passive resistors,and current-steering MOS transistors as a variable resistor is proposed.T...A fully differential R-MOSFET-C fourth-order Bessel active lowpass filter employing fully differential operational amplifier,passive resistors,and current-steering MOS transistors as a variable resistor is proposed.This proposed implementation relies on the tunability of current-steering MOS transistors operating in the triode region counteracting the concert deviation of resistor in the integrated circuit manufacturing technology in orde r that the group delay of Bessel active filter could be designed accurately.The amplifier is not only with voltage common-mode negative feedback,but also with current common-mode negative feedback,which will benefit for the stability of its D C operating point.0.75μs group delay fourth-order Bessel lowpass filter,whic h is synthesized according to passive doubly terminated RLC prototype lowpass filter,demonstrates better than -65dB THD using 100kHz,2.5V pp signal in Taiwan UMC 2P2M(2-poly,2-metal)5.0V,0.5μm CMOS technology.展开更多
文摘Waveform control method was commonly adopted to reduce the spatter of CO2 arc welding and improve the weld formation. It certainly would reduce the self-regulation ability of arc due to the adoption of segmented constant current control which especially led to arc＂ blowout with the abrupt change oat＂ arc＂ length or downward welding. Therefore alterative wire-feed system based on arc voltage negative feedback was put forward to improve the .stability of arc＂ length in this paper. Double closed-loop and double fuzzy P1 regulation were adopted in this system. Fuzzy control of induced voltage was adopted in the inner-loop which improved the stability and fast response of wire-feed system. Fuzz）＂ control of arc＂ voltage negative feedback was used in the outer-loop whose output .served as the input of negative feedback regulation of inner-loop induced voltage. This method could remain arc＂ length and weld penetration unchan, ged on the basils of reducing spatter and improving formation and it was proved by downward welding tests.
文摘A fully differential R-MOSFET-C fourth-order Bessel active lowpass filter employing fully differential operational amplifier,passive resistors,and current-steering MOS transistors as a variable resistor is proposed.This proposed implementation relies on the tunability of current-steering MOS transistors operating in the triode region counteracting the concert deviation of resistor in the integrated circuit manufacturing technology in orde r that the group delay of Bessel active filter could be designed accurately.The amplifier is not only with voltage common-mode negative feedback,but also with current common-mode negative feedback,which will benefit for the stability of its D C operating point.0.75μs group delay fourth-order Bessel lowpass filter,whic h is synthesized according to passive doubly terminated RLC prototype lowpass filter,demonstrates better than -65dB THD using 100kHz,2.5V pp signal in Taiwan UMC 2P2M(2-poly,2-metal)5.0V,0.5μm CMOS technology.
