Through research on the application of hydroviscous speed-adjusting clutch in belt conveyor, this paper concluded that hydroviscous speed-adjusting clutch has many advantages such as controllable start and stop, overl...Through research on the application of hydroviscous speed-adjusting clutch in belt conveyor, this paper concluded that hydroviscous speed-adjusting clutch has many advantages such as controllable start and stop, overload protection and multi-motor power equilibrium. But its theory when used in large power fan and pump could not meet the needs of belt conveyor soft-start operation. Focusing on the theo- retical analysis of the lubrication oil flow needed by the transmission procedure to form the oil-film. Put forward concrete calculation methods of lubrication flow and how to de- cide number of oil-films used in belt conveyor.展开更多
A fully integrated soft-start circuit for DC-DC buck converters is presented. The proposed high speed soft-start circuit is made of two sections： an overshoot suppression circuit and an inrush current suppression cir...A fully integrated soft-start circuit for DC-DC buck converters is presented. The proposed high speed soft-start circuit is made of two sections： an overshoot suppression circuit and an inrush current suppression circuit. The overshoot suppression circuit is presented to control the input of the error amplifier to make output voltage limit increase in steps without using an external capacitor. A variable clock signal is adopted in the inrush current suppression circuit to increase the duty cycle of the system and suppress the inrush current. The DC-DC converter with the proposed soft-start circuit has been fabricated with a standard 0.13 um CMOS process. Experimental results show that the proposed high speed soft-start circuit has achieved less than 50 us start-up time. The inductor current and the output voltage increase smoothly over the whole load range.展开更多
Induction motors are the most widespread rotating electrical machines in industry.Predictive maintenance of the motors is of crucial importance due to the fact that unexpected faults in those machines can lead to huge...Induction motors are the most widespread rotating electrical machines in industry.Predictive maintenance of the motors is of crucial importance due to the fact that unexpected faults in those machines can lead to huge economic losses for the corresponding companies.Over recent years,there is an increasing use of industrial induction motors operated by different types of drives,which have different functionalities.Among them,the use of soft-starters has proliferated due to the inherent benefits provided by these drives:they damp the high starting currents,enabling the soft startup of the motors and avoiding undesirable commutation transients introduced by other starting modalities.In spite of these advantages,they do not avoid the possible occurrence of rotor damages,one of the most common faults in this type of motors.Few works have proposed predictive maintenance techniques that are aimed to diagnose the rotor condition in soft-started machines and even fewer have demonstrated the validity of their methods in real motors.This work presents,for the first time,the massive validation of a rotor fault diagnosis methodology in soft-started induction motors.Industrial and laboratory and induction motors started under different types of soft-starters and with diverse rotor fault conditions are considered in the work.The results prove the potential of the approach for the reliable assessment of the rotor condition in such machines.展开更多
同步电机软起动是由静止变频器(Static Frequency Converter,SFC)将同步电机从静止逐渐拖动至额定转速。但SFC短时和频繁起动会造成大量谐波,该谐波施加在同步电机电枢绕组对同步电机造成不可逆的危害。本文首先图解分析了同步电机软起...同步电机软起动是由静止变频器(Static Frequency Converter,SFC)将同步电机从静止逐渐拖动至额定转速。但SFC短时和频繁起动会造成大量谐波,该谐波施加在同步电机电枢绕组对同步电机造成不可逆的危害。本文首先图解分析了同步电机软起动低速和高速阶段的换相过程,由此推导出各阶段电枢电流模型,从而分析得出电枢电流谐波特性。最后,搭建出同步电机软起动的Matlab/Simulink模型,验证本文推导的准确性。展开更多
文摘Through research on the application of hydroviscous speed-adjusting clutch in belt conveyor, this paper concluded that hydroviscous speed-adjusting clutch has many advantages such as controllable start and stop, overload protection and multi-motor power equilibrium. But its theory when used in large power fan and pump could not meet the needs of belt conveyor soft-start operation. Focusing on the theo- retical analysis of the lubrication oil flow needed by the transmission procedure to form the oil-film. Put forward concrete calculation methods of lubrication flow and how to de- cide number of oil-films used in belt conveyor.
基金Project supported by the Natural Science Foundation of Jiangsu,China(No.BK2011059)the Program for New Century Excellent Talents in University(NCET- 10-0331)the Qing Lan Project
文摘A fully integrated soft-start circuit for DC-DC buck converters is presented. The proposed high speed soft-start circuit is made of two sections： an overshoot suppression circuit and an inrush current suppression circuit. The overshoot suppression circuit is presented to control the input of the error amplifier to make output voltage limit increase in steps without using an external capacitor. A variable clock signal is adopted in the inrush current suppression circuit to increase the duty cycle of the system and suppress the inrush current. The DC-DC converter with the proposed soft-start circuit has been fabricated with a standard 0.13 um CMOS process. Experimental results show that the proposed high speed soft-start circuit has achieved less than 50 us start-up time. The inductor current and the output voltage increase smoothly over the whole load range.
基金Supported by the Spanish‘Ministerio de Economia y Competitividad’(MINECO)FEDER program in the framework of the‘Proyectos I+D del Subprograma de Generacion de Conocimiento,Programa Estatal de Fomento de la Investigacion Cientifica y Tecnica de Excelencia’(ref:DPI2014-52842-P).”。
文摘Induction motors are the most widespread rotating electrical machines in industry.Predictive maintenance of the motors is of crucial importance due to the fact that unexpected faults in those machines can lead to huge economic losses for the corresponding companies.Over recent years,there is an increasing use of industrial induction motors operated by different types of drives,which have different functionalities.Among them,the use of soft-starters has proliferated due to the inherent benefits provided by these drives:they damp the high starting currents,enabling the soft startup of the motors and avoiding undesirable commutation transients introduced by other starting modalities.In spite of these advantages,they do not avoid the possible occurrence of rotor damages,one of the most common faults in this type of motors.Few works have proposed predictive maintenance techniques that are aimed to diagnose the rotor condition in soft-started machines and even fewer have demonstrated the validity of their methods in real motors.This work presents,for the first time,the massive validation of a rotor fault diagnosis methodology in soft-started induction motors.Industrial and laboratory and induction motors started under different types of soft-starters and with diverse rotor fault conditions are considered in the work.The results prove the potential of the approach for the reliable assessment of the rotor condition in such machines.
文摘同步电机软起动是由静止变频器(Static Frequency Converter,SFC)将同步电机从静止逐渐拖动至额定转速。但SFC短时和频繁起动会造成大量谐波,该谐波施加在同步电机电枢绕组对同步电机造成不可逆的危害。本文首先图解分析了同步电机软起动低速和高速阶段的换相过程,由此推导出各阶段电枢电流模型,从而分析得出电枢电流谐波特性。最后,搭建出同步电机软起动的Matlab/Simulink模型,验证本文推导的准确性。
