浅谈高压变频调速变压器及高压变频系统结构

介绍了高压变频调速变压器及高压变频器系统的基本原理及结构,详细论述了系统各组成部分的功能,并进行了举例说明。     

变频器数字语音设计

随着电子元器件以及控制技术的发展．变频器的性能越来越高．人性化的设计要求变得越来越突出。美国信息存贮器件公司的ISD1420单片语音录放芯片．以其优良的性能正被广泛应用。本文即是针对变频器人性化设计的要求．采用ATmega16L单片机控制．利用ID1420语音芯片，实现了变频器高性能语音提示的功能。     

基于直流供电技术的电压暂降保护系统研究

变频器在软启动、变频调速、优化设计、经济运行等方面具有明显优势,得到广泛应用。在电压暂降期间,变频器会因低压保护而跳闸,造成连续性生产企业非计划停运,带来巨大的经济损失和事故。根据变频器交-直-交的特性,结合电力电子技术,研究开发了两种基于直流供电技术的电压暂降保护系统。两种保护系统分别利用电网残压和蓄电池组作为能量来源,通过Boost DC/DC变换器,输出恒定的直流电压,为变频器直流母线提供恒定的直流电。实验数据和现场应用表明,该两种电压暂降保护系统可以确保变频器在电压暂降期间正常运行,大大提高了供电可靠性,为用户避免了大量的经济损失。     

基于单片机C8051F500的无刷直流电机控制研究

永磁无刷直流电机是近些年发展起来的一种新型电机,具有效率高、调速性能好、启动转矩大等诸多优点,在运动控制领域中的应用日趋广泛。基于电机专用控制芯片MC33035,采用单片机C8051F500为主控芯片,设计一款无刷直流电机智能控制器,实现对无刷直流电机启动停止、正反转、调速、转速显示等控制。通过简要介绍无刷直流电机工作原理,使用MATLAB/Simulink对控制系统进行建模仿真,对无刷直流电机控制系统进行软、硬件设计。实验结果表明,该控制系统运行稳定,抗干扰性强,具有良好的市场应用价值。     

Power conversion system for high altitude wind power generation with medium voltage AC transmission

High Altitude Wind Power (HAWP) generating system provides clean energy at low cost and high capacity factor due to reduced size of the turbine and high speed streamlined wind at high altitude. An air-borne wind turbine (AWT) at high altitude extracts kinetic energy from wind using buoyancy provided by the blimp/aerostat. The generated electrical power is then transmitted to the ground based station (without any power conditioning) using the transmission lines (tether). The power conversion system (PCS) for harnessing HAWP is proposed in this paper. The proposed PCS consists of a three-level neutral point clamped (NPC) rectifier, a three-level NPC DC–DC converter followed by a two-level inverter. Modelling, design and control of the PCS are presented and discussed. The PCS provides generation side maximum power-point tracking (MPPT) using sensorless optimal torque control technique. The DC–DC converter provides electrical isolation as well as voltage step-down functions. A modified proportional resonant (PR) control which can selectively eliminate lower order current harmonics of the grid-connected inverter is also presented. The proposed control scheme of the PCS is evaluated through simulation studies using software programs like PSIM and MATLAB. A scaled-down 1 kW laboratory prototype of the complete PCS is designed, built and tested. The experimental test results obtained validate the proposed control scheme for efficient power generation from high altitude wind and interface to the grid/load.     

森兰SB70 690V 1100kW大功率变频器在胶带输送机上的节能运用

从矿山运送矿石到到生产厂房,只要存在一定的高差,具有一定的位能,就可用变频器为再生能量传动系统,可将再生能量反馈回电网。一般情况是每天24小时连续不断运送,运送的矿石量很大,电机发电量也大,电能回馈也多。从目前国内矿山的情况看,运送矿石基本上都是用大吨位的矿用汽车从山上往山下一趟一趟运送,既浪费了油料,又污染了环境,而且还占用大量耕地,很可惜。用变频器驱动下运胶带输送机带发电机运送矿石,可回收大量的电能,降低生产成本,提升企业的竞争力意义重大,这种方法值得推广。     

台达变频器在矿用绳锯机系统的应用

本文介绍了一种矿用绳锯机控制系统,该系统使用可编程控制器、人机界面和变频器等工控元件设计构成,相比目前市场中的通用型矿用绳锯机,具有操作简单、切割效果更好等优点。     

Solution-processed ytterbium oxide dielectrics for low-voltage thin-film transistors and inverters

High permittivity (high k) metal-oxide thin films fabricated via solution processes have recently received much attention for the construction of low-operating voltage and high-performance thin-film transistors (TFTs). In this report, amorphous ytterbium oxide (Yb₂O₃) thin films were fabricated by spin coating and their applications in TFTs were explored. The physical properties of the solution-processed Yb₂O₃ thin films processed at different annealing temperatures were systematically investigated using various characterization techniques. To explore the feasibility of the Yb₂O₃ thin films as gate dielectrics for oxide TFTs, In₂O₃ TFTs based on Yb₂O₃ dielectrics were integrated. All the devices could be operated at 3 V, which is critical for the applications in portable, battery-driven, and low-power electronic devices. The optimized In₂O₃/Yb₂O₃ TFT exhibits high electrical performances, including field-effect mobility of 4.98 cm²/V s, on/off current ratio of ~ 10⁶, turn-on voltage around 0 V, and subthreshold swing of 70 mV/decade, respectively. To demonstrate the potential of In₂O₃/Yb₂O₃ TFT toward more complex logic application, the unipolar inverter was further constructed.     

Price development of photovoltaic modules,inverters, and systems in the Netherlands in 2012

Since 2010 the Dutch photovoltaic (PV) market has been growing fast, with around doubling of installed capacity in 2011 and 2012. Four quarterly inventories have been made in 2012 for modules, inverters, and systems that are presently available for purchase in the Netherlands. We have found that the average selling price of modules, inverters, and systems decreased with 44.3, 14, and 7.3–10.2%, respectively: average selling prices are 1.26 €/Wp, 0.41 €/Wp, and 1.46 €/Wp for modules, inverters, and systems on tilted roofs, respectively, at the end of 2012. Average installation costs amount to 0.43 €/Wp. Using an energy yield of 900 kWh/kWp, 25 years system lifetime, 6% discount rate, and 1% operation and maintenance (O&M) cost, a levelized cost of electricity (LCOE) is calculated for a 2.5 kWp system to be 0.194 €/kWh for a system price of 1.98 €/Wp (including installation). Grid parity conditions are apparent, with electricity retail prices of around 0.23 €/kWh.     

火力发电厂用变频器的常见故障及对策

介绍了变频器在使用过程中常见的参数设定问题和常见故障报警的产生原因和对策;总结了在变频器选型、使用、维护等相关方面的一些方法和经验。