This paper presents a new ZVT （zero-voltage transition） single-stage ac-to-dc converter using PWM （pulse width modulation） and HF （high frequency） transformer isolation with capacitive output filter. In this con...This paper presents a new ZVT （zero-voltage transition） single-stage ac-to-dc converter using PWM （pulse width modulation） and HF （high frequency） transformer isolation with capacitive output filter. In this converter a front-end power factor corrected boost stage integrates with a cascaded dc-to-dc bridge HF converter. The front-end boost converter operates in discontinuous current mode and ensures natural power factor correction with very simple control. The auxiliary circuit of this topology deals with very small power and is placed out of the main power path. As a result, the auxiliary circuit components have smaller power rating as opposed to main converter components. Also, output rectifier voltage is clamped to output voltage due to capacitive output filter. Identification and analyses of different operating modes of this converter are presented. Based on these analyses design example of a 50 kHz, 48 V, 1 kW ac-to-dc converter is presented. PSPICE simulation results of the designed converter are presented and explained to verify the performance of this converter.展开更多
The transmision mechanism of vibrational power flow in the complex flekible coupled system of machinery mouned on a multi-storey plant building via isolators are studied in this paper from the viewpoint of energy. In ...The transmision mechanism of vibrational power flow in the complex flekible coupled system of machinery mouned on a multi-storey plant building via isolators are studied in this paper from the viewpoint of energy. In view of practical isolation designs in engineering,an asymmetric isolation system with mtiltiple isolators on a fiekible foundation is modeled, in which the interactions between the machine and the floor, and among different mouating points are taken illto account. Moreover, the transmission characteristics of power flow in the system concerned are analyzed with the use of subsystem mobility synthetic techaique. Further more,the power flow spectra of the asymmetric system are calculated and compared with those of symmetric one to reveal the effects of asymmetricity and system parameters on the power flow.Finally, new approaches to the control of structural vibration and acoustics for this kin of problems are proposed.展开更多
文摘This paper presents a new ZVT （zero-voltage transition） single-stage ac-to-dc converter using PWM （pulse width modulation） and HF （high frequency） transformer isolation with capacitive output filter. In this converter a front-end power factor corrected boost stage integrates with a cascaded dc-to-dc bridge HF converter. The front-end boost converter operates in discontinuous current mode and ensures natural power factor correction with very simple control. The auxiliary circuit of this topology deals with very small power and is placed out of the main power path. As a result, the auxiliary circuit components have smaller power rating as opposed to main converter components. Also, output rectifier voltage is clamped to output voltage due to capacitive output filter. Identification and analyses of different operating modes of this converter are presented. Based on these analyses design example of a 50 kHz, 48 V, 1 kW ac-to-dc converter is presented. PSPICE simulation results of the designed converter are presented and explained to verify the performance of this converter.
文摘The transmision mechanism of vibrational power flow in the complex flekible coupled system of machinery mouned on a multi-storey plant building via isolators are studied in this paper from the viewpoint of energy. In view of practical isolation designs in engineering,an asymmetric isolation system with mtiltiple isolators on a fiekible foundation is modeled, in which the interactions between the machine and the floor, and among different mouating points are taken illto account. Moreover, the transmission characteristics of power flow in the system concerned are analyzed with the use of subsystem mobility synthetic techaique. Further more,the power flow spectra of the asymmetric system are calculated and compared with those of symmetric one to reveal the effects of asymmetricity and system parameters on the power flow.Finally, new approaches to the control of structural vibration and acoustics for this kin of problems are proposed.
