智能化中高压变频器实载试验平台的实现

中、高压变频器产量越来越多，但试验手段大多比较落后，一般采用带电机空转的方法。本文介绍了一个高压变频器试验平台，通过该平台可以对电压等级在3kV～10kV、功率在5000kW以下的变频器进行实载试验。     

数字电路中电源电压瞬间下降的成因及改进

通过分析数字集成芯片多输出中电源电压瞬间下降的原因,对常规驱动电路结构进行改进。改进后单输出电路的峰值电流降为原来的2/3,再通过优化版图的电源布线,能有效防止电源电压下降,使芯片正常稳定地工作。     

超级电容在手机电源中的应用

超级电容又称法拉电容,是指其容量为法拉级的电容。文章介绍了应用超级电容作为手机电池的总体思路并重点介绍了其充电电路、升压电路和控制电路的设计。该电池具有充电快、寿命长、免维护并且环保等特点。     

通信交流供电方案初探

在通信供电系统中,与直流供电系统相比,从设计、设备技术,到运行维护管理,交流供电系统都有所滞后。借鉴直流供电系统经验,通过应用N X并联逆变器模块热插拔技术,实行分散式供电,进而改变传统的以UPS为核心的集中供电模式,则可在很大程度上解决一直困扰着我们的交流供电系统成本高和可靠性低的难题。     

超高压大容量铝电解电容器的研制

分析了大功率设备用超高压大容量铝电解电容器的特点,通过研制工作电解液、制订制作工艺及零部件设计方案,研制出的超高压大容量铝电解电容器具有损耗角正切小(tgδ为0.25)、承受纹波电流能力强(100 Hz,2.12～27.8 A)及寿命长的特点,耐久性达到85℃,5 000 h。     

Magnetic Properties of Fe-Doped Rutile

Ball-milling method was applied to dissolve Fe into titanium dioxide (TiO₂). X-ray diffraction indicated the starting anatase changed to a rutile-type structure with oxygen deficiency after ball milling. Transmission electron microscopy and X-ray absorption experiments were conducted to examine the possible existence of magnetic impurities in the ball-milled powders after they were leached in HCl solutions. Temperature dependence of the resistivity shows semiconducting behavior and the magnetic hysteresis loops at 5 and 300 K exhibit ferromagnetic characteristics. Fe-doped TiO₂ films were also prepared by pulsed laser deposition. The magnetic properties of the films are discussed.     

Fracture toughness of PAN-based carbon fibers estimated from strength-mirror size relation

Fracture toughness (K_IC) of representative high-strength type PAN (polyacrylonitrile)-based carbon fibers, Torayca™ T300 and T800H, with or without artificial surface defects, were estimated to be ca. 1 MPam^1/2 from the tensile strength vs. fracture mirror size relation, assuming a constant crack-to-mirror size ratio. The corresponding critical energy release rate (Γ) was ca. 7.4 J m⁻², which was close to the value derived from the reported surface energies for a graphite crystal. Similar K_IC values were obtained for the old-type PAN-based carbon fibers from the reported data by the use of the present estimation procedure.