In this paper, by using a matrix technique, a dynamic model of high power factor induction motor with floating winding in parallel connection with capacitors is established. Then, the starting performance of this mot...In this paper, by using a matrix technique, a dynamic model of high power factor induction motor with floating winding in parallel connection with capacitors is established. Then, the starting performance of this motor is analyzed by computer simulation. By comparison of the tested and computed results, which are in good agreement, the dynamic model and simulative method are verified.展开更多
A new type of high power LED drivers is proposed by adopting an improved two-stages non-isolated configuration. In order to improve power factor and achieve accurate average current control under universal input volta...A new type of high power LED drivers is proposed by adopting an improved two-stages non-isolated configuration. In order to improve power factor and achieve accurate average current control under universal input voltages ranging from 100 Vrms to 240 Vrms, the power factor correction and average current mode control methods operating in continuous current conduction mode are designed and implemented. With the LUMILEDS emitter type LEDs, a laboratory prototype is built and measured. And from the measured results, it could be concluded that the proposed driver has many better performances such as high power factor, low current harmonic, accurate average current control and switch protection.展开更多
The development process of high-voltage electric power equipment maintenance was introduced. It is pointed out that the trend of high-voltage electric power equipment maintenance is so called condition-based maintenan...The development process of high-voltage electric power equipment maintenance was introduced. It is pointed out that the trend of high-voltage electric power equipment maintenance is so called condition-based maintenance. With the development of computer technology and sensors, on-line monitoring of high-voltage electric power equipment has developed rapidly. By introducing the main principle of Schering bridge to measure tanδ, the way of on-line monitoring of high-voltage electric power equipment was explained. Difference methods of on-line monitoring of insulation parameters for 35 kV substation were discussed. Finally, the shortcomings as well as its tendency of on-line monitoring were analyzed.展开更多
A high efficiency, high power factor, and linear constant current LED driver based on adaptive seg- mented linear architecture is presented. When the input voltage varied, the proposed LED driver automatically switche...A high efficiency, high power factor, and linear constant current LED driver based on adaptive seg- mented linear architecture is presented. When the input voltage varied, the proposed LED driver automatically switched over LED strings according to the segmented LED voltage drop, which increased the LED lighting time. The efficiency and power factor are improved, while the system design is simplified by this control scheme. Without the usage of electrolytic capacitor and magnetic components, the proposed driver possesses advantages of smaller size, longer lifetime and lower cost over others. The proposed driver is implemented in 0.8 μm 5 V/40 V HVCMOS process, which occupies an active area of 820× 920μm2. The measured results show that the average value of the internal reference voltage is 500 4- 7 mV, with a standard deviation of only 4.629 mV, thus LED current can be set accurately. Under 220 V root mean square 50 Hz utility voltage and the number ratio of the three LED strings being 47 ： 17 ： 16, the system can realize a high power factor of 0.974 and power conversion efficiency of 93.4%.展开更多
为了解决高压大功率换流器谐波含量高、功率因数低和零电流关断(zero current switching,ZCS)问题,文中以7电平电流重注入换流器(seven level current reinjection current source converter,SLCR-CSC)为对象,研究其电流控制特性。通过...为了解决高压大功率换流器谐波含量高、功率因数低和零电流关断(zero current switching,ZCS)问题,文中以7电平电流重注入换流器(seven level current reinjection current source converter,SLCR-CSC)为对象,研究其电流控制特性。通过分析多绕组变压器磁化电流合成原理,构建了重注入变压器电流合成数学模型,给出电流重注入变压器和功率器件的选型依据,以及重注入电流通路控制原理。MATLAB/Simulink仿真结果表明其在谐波消除的同时,实现电流过零关断和单位功率因数运行。设计1 MW物理实验平台,实验结果与理论仿真基本一致。展开更多
文摘In this paper, by using a matrix technique, a dynamic model of high power factor induction motor with floating winding in parallel connection with capacitors is established. Then, the starting performance of this motor is analyzed by computer simulation. By comparison of the tested and computed results, which are in good agreement, the dynamic model and simulative method are verified.
文摘A new type of high power LED drivers is proposed by adopting an improved two-stages non-isolated configuration. In order to improve power factor and achieve accurate average current control under universal input voltages ranging from 100 Vrms to 240 Vrms, the power factor correction and average current mode control methods operating in continuous current conduction mode are designed and implemented. With the LUMILEDS emitter type LEDs, a laboratory prototype is built and measured. And from the measured results, it could be concluded that the proposed driver has many better performances such as high power factor, low current harmonic, accurate average current control and switch protection.
文摘The development process of high-voltage electric power equipment maintenance was introduced. It is pointed out that the trend of high-voltage electric power equipment maintenance is so called condition-based maintenance. With the development of computer technology and sensors, on-line monitoring of high-voltage electric power equipment has developed rapidly. By introducing the main principle of Schering bridge to measure tanδ, the way of on-line monitoring of high-voltage electric power equipment was explained. Difference methods of on-line monitoring of insulation parameters for 35 kV substation were discussed. Finally, the shortcomings as well as its tendency of on-line monitoring were analyzed.
基金supported by the National Natural Science Foundation of China(Nos.61234002,61322405,61306044,61376033)
文摘A high efficiency, high power factor, and linear constant current LED driver based on adaptive seg- mented linear architecture is presented. When the input voltage varied, the proposed LED driver automatically switched over LED strings according to the segmented LED voltage drop, which increased the LED lighting time. The efficiency and power factor are improved, while the system design is simplified by this control scheme. Without the usage of electrolytic capacitor and magnetic components, the proposed driver possesses advantages of smaller size, longer lifetime and lower cost over others. The proposed driver is implemented in 0.8 μm 5 V/40 V HVCMOS process, which occupies an active area of 820× 920μm2. The measured results show that the average value of the internal reference voltage is 500 4- 7 mV, with a standard deviation of only 4.629 mV, thus LED current can be set accurately. Under 220 V root mean square 50 Hz utility voltage and the number ratio of the three LED strings being 47 ： 17 ： 16, the system can realize a high power factor of 0.974 and power conversion efficiency of 93.4%.
文摘为了解决高压大功率换流器谐波含量高、功率因数低和零电流关断(zero current switching,ZCS)问题,文中以7电平电流重注入换流器(seven level current reinjection current source converter,SLCR-CSC)为对象,研究其电流控制特性。通过分析多绕组变压器磁化电流合成原理,构建了重注入变压器电流合成数学模型,给出电流重注入变压器和功率器件的选型依据,以及重注入电流通路控制原理。MATLAB/Simulink仿真结果表明其在谐波消除的同时,实现电流过零关断和单位功率因数运行。设计1 MW物理实验平台,实验结果与理论仿真基本一致。
