浅谈太阳能LED照明技术

本文在LED恒流驱动、散热处理两个方面介绍了LED光源技术应用,并阐述了太阳能灯具与LED光源的结合的优势。     

瞬时无功功率理论谐波检测中低通滤波器的应用

对在谐波实时检测电路中用到的低通滤波器对谐波电流检测效果的影响作了仿真研究。特别针对低通滤波器在谐波实时检测中的应用所要注意的低通滤波器设计参数做了深入研究。结果证明,该方法在电网谐波检测应用中满足快速、精确的要求,具有很好实时性。     

新型“双重Δ调制”跟踪控制方法研究

提出了一种基于幅值△调制和时间△调制相结合的"双重△调制"电流跟踪控制新方法.将单边滞环电流比较器和开关周期定时器相结合,通过设定滞环比较器的下限值决定实际输出电流的下限,由定时器的定时周期决定实际输出电流的上限,该方法只需一个无滞环单阈值比较器,因而电路简单、动态响应快,特别是时间量化的载波定时保证了开关频率固定不变.给出了避免跟踪失步的一般性条件.仿真和实验结果均证明了该方法的有效性.     

变电流间歇快速充电法

本文已建立变电流间歇快速充电法,它对VRLA蓄电池在电动车应用方面具有重要意义。它的法参数有初始电流、转换电压、停充时间、变电流方式等,并通过试验给出这些参数。它与标准充电方比较,充电时间缩短,且给出更多放电容量。在间歇充电中采用变电流方式比脉冲电流好。变电流间歇电时间190min,放电容量92％,而脉冲电流间歇充电时间为290min,放电容量为87％。电池荷电态和度影响已讨论。快速充电用于循环试验时,经几次循环后要用标准充电法将电池恢复至完全充电态。     

Investigation of performance of UPFC without DC link capacitor

This paper presents an analysis of the dynamic operation of unified power flow controller without DC link capacitor. In this scheme of UPFC the shunt converter present in the static synchronous compensator is operated as a current source rectifier, which maintains a fixed DC voltage and DC current on the DC link without capacitor. The capacitor in the DC link is replaced by an AC filter on the line side with a very small value to reduce higher order harmonics. The voltage source inverter present in the series compensator is operated with space vector modulation technique. The proposed scheme is fully validated through digital simulation. The simulated results show that the DC link voltage is maintained constant without DC link capacitor; STATCOM provides good voltage regulation and static synchronous series compensator influences power flow over the transmission line. Transient responses of single machine infinite bus power system have also been presented.     

测定保护用电流互感器铁心励磁特性的直流法

介绍了测定保护用电流互感器铁心励磁特性的直流法和注意事项以及主要参数的测定.     

直线步进电动机闭环控制系统研究

根据直线脉冲电机的特性和控制要求,以89C51单片机为核心控制单元,采用专用集成驱动芯片PBL3717A作为功率驱动器件进行闭环控制并通过硬件和软件设计,实现对直线脉冲电机的精确定位和调速,解决了直线脉冲电机行程末端的机械冲击问题。     

电流互感器故障诊断与分析

对电流互感器故障进行了诊断与分析。     

基于感受量的接地距离保护整定方法探讨

针对接地距离保护整定计算中基于助增系数的整定方法的不足，探讨了基于感受量的整定方法，给出了普遍适用的整定计算公式。该方法能够实现接地距离保护与配合保护的整定，全面提高接地距离保护的灵敏度，并且易于计算机实现。该方法已经运用于工程实际中，工程算例验证了本方法的正确性和有效性。     

Post-process thermal treatment for microwave power improvement of AlGaN/GaN HEMTs

The effects of post-process rapid thermal annealing (RTA) treatment after device fabrication on direct current, microwave and power performances of AlGaN/GaN high electron mobility transistors (HEMTs) with a gate-length of 0.2 μm were fully investigated. By 3 min post-process RTA treatment at 350 °C under N₂ atmosphere, the direct current (DC), radio frequency (RF) small signal and power performances of AlGaN/GaN HEMTs have been much improved. The output power, power gain and power added efficiency (PAE) of GaN HEMT device with gate wide of 1 mm increase from 37.09 dBm, 6.09 dB and 42.79% to 38.22 dBm, 7.22 dB and 67.3%. The post-process RTA after device fabrication has two merits. On the one hand, it improves passivation effect of SiN_x dielectric layer on AlGaN/GaN HEMT surface, suppressing RF current dispersion. On the other hand, it helps recover dry-etch damage at the Schottky metal/AlGaN interface, leading to reduction of reverse Schottky leakage current.