甲苯歧化装置紧急泄压工况的模拟研究

循环氢中断是甲苯歧化装置中十分严重的事故,通常设置有针对该工况的紧急泄压停车系统(ESD)。在保证装置在较短时间内完成泄压的同时,必须确保设备和催化剂的安全,因此确定一个适当的泄压速度尤为重要。紧急泄压是一种动态的过程,本文利用DYNSIM动态模拟软件,以180万吨/年甲苯歧化装置为研究对象,建立该装置氢气循环反应系统的动态模型,利用该模型研究了紧急泄压工况下泄压速度对装置操作参数的影响。通过调整动态模型中控制阀的开度,实现对不同泄压速度的模拟,考察了泄压速度与泄压时间和反应进出料换热器温降速率的关系,验证了反应器压差的变化趋势。模拟结果显示,泄压速度与泄压时间成反比关系、与反应进出料换热器的温降速率成正比关系,紧急泄压工况反应器压差会大幅度下降。在此基础上得出了较优的泄放流量,可用于泄压限流孔板的设计,保证反应系统的安全运行。     

一种可变门极电阻的大功率IGBT驱动

通过分析大功率IGBT寄生参数及主功率回路寄生参数对IGBT驱动的影响,提出了一种基于可变门板电阻的驱动电路,提高了驱动模块的产品兼容性,实现了驱动器对IGBT开关特性的精确控制,有效抑制开关过程中由于di/dt引起的电压尖峰.最后在Sabor中搭建了型号为FZ1500R33HE3的大功率IGBT的仿真模型,并进行仿真分析;通过搭建实物平台进行了双脉冲实验.仿真和实验结果表明,该驱动电路具有可行性.     

采用IGBT的直流电机调速控制器

介绍直流电机调速控制器的原理及其系统构成.其主功率开关器件选用绝缘栅控双极型晶体管——IGBT.控制电路采用速度(或电压)、电流双环调节,采用TL494作为脉宽调制器以驱动IGBT,使新波频率高达18KHz缩小了系统体积,并使运行无噪音污染.本文重点分析了IGBT的控制和保护电路.     

基于绝缘液体充填封装RFMEMS开关特性分析

提出并设计一种采用绝缘液体充填封装的RF MEMS开关,分析其工作原理,并以高压油、蓖麻油、甘油为绝缘液体充填封装,仿真分析绝缘液体对RF MEMS开关的驱动电压、冲击速度、响应时间、开关电容等方面的影响。结果表明:绝缘液体充填封装有效地将驱动电压降为原来的1/εr,降低上极板对下极板的冲击速度。对3种液态封装材料性能分析,蓖麻油效果最好:阈值电压下降了一半,约为10 V;当驱动电压为20 V时,响应时间为40.6μs,优于高压油(91.3μs)、甘油(89.9μs),冲击速度约为1.26 m/s。     

一种基于多阈值保护的大功率IGBT驱动

通过分析VCE检测电路的传递函数,合理配置检测电路电气参数,根据IGBT发生短路时的特点,提出了一种基于多阈值过流保护和变电阻式软关断的大功率IGBT驱动保护策略,实现了驱动器对IGBT有效控制,并抑制开关过程中由于di/dt引起的电压尖峰.最后在Sabor中搭建了型号为FZ1500R33HE3的大功率IGBT的仿真模型,进行仿真分析,并搭建实物平台进行了短路保护实验.仿真和实验结果表明该驱动电路具有可行性.     

IGBT驱动器在高压电机调速系统中的应用研究

介绍了一种以智能门板驱动模块IGD515E为核心的IGBT驱动电路在斩波式内反馈串级调速系统中的典型应用,包括内反馈串级调速系统的工作原理、IGBT斩波器驱动电路参数选择和计算方法.通过实验验证,实际中的驱动电压波形及斩波器工作波形都表明,本文所设计的驱动电路工作稳定,具有优良的驱动和保护性能.     

掩膜电解电源频率分析及整流建模仿真

通过掩膜电解加工方法对生物表面微织构进行研究,针对特殊工艺的需要,设计了一种高频高压脉冲电源。分析了开关器件的特点,在综合考虑功率、开关速度等因素情况下,对工作频率及波形失真进行了推导。采用IGBT作为开关器件,利用三相桥式全控整流电路,把工频交流电整形为波动平滑的直流电。在Matlab/SimPowerSystems环境中构建了电源模型并进行了仿真,仿真结果表明,各节点的实验波形符合预期。     

压电发电系统无源同步开关设计及实验研究

压电材料是一种价格低廉,性能稳定的储能、换能材料。利用磁铁结合压电振子,通过电机转动,可以无接触驱动压电振子进行振动。电机旋转一周,不同磁极的磁铁交替驱动压电振子振动,改变电机转速使压电振子产生谐振可获得最大输出电压。同时,磁铁周期性对无源磁性开关进行吸合可产生同步开关信号,合理布置磁性开关使磁性开关信号与压电波形的正峰值与负峰值进行同步,搭建了实验装置并进行了实验,结果表明磁性开关可以很精确的在压电电压波形的两个峰值进行闭合。这为SECE、SSHI电路实际使用提供了一种可行的同步开关设计方法。     

利用PSPICE软件仿真在线式UPS

叙述了在线式UPS的电路组成，利用PSPICE仿真软件对电路进行了仿真。采用20kHzPWM驱动IGBT逆变器；比较开环和闭环输出电压波形。     

基于电流反馈的IGBT有源栅极驱动方法研究

IGBT开关过程中di/dt与du/dt的大小决定着电流过冲、电压过冲和通断损耗的大小。为使IGBT稳定高效工作,提出一种基于di/dt和du/dt反馈的栅极驱动方法,在IGBT开通时,与di/dt成正比的可控电流反馈到栅极;同样,在IGBT关断时,与du/dt成正比的可控电流反馈到栅极。通过调节反馈到栅极的电流值,实现对di/dt与du/dt的控制,从而抑制尖峰电流和过压损坏的产生。仿真及实验结果验证了理论分析的正确性与可行性。     

Analysis of the driving characteristics for an ACPDP with an auxiliary electrode using the voltage‐transfer closed surface

Abstract— The driving characteristics and wall‐charge model of an ac plasma‐display panel (ACPDP) with an auxiliary electrode were investigated by using voltage‐transfer closed‐surface modeling. To understand the wall‐charge behavior of an ACPDP with an auxiliary electrode qualitatively, voltage‐transfer closed‐surface analysis was applied to a test panel under the full driving waveform. The voltage‐transfer closed surfaces were obtained after the sustain, reset, and address periods, when the full‐stage driving waveform was employed with the test panel. As a result, it was proven that the wall‐charge model predicted in the previous work corresponded with the wall‐charge behavior of an ACPDP with an auxiliary electrode. Also, based on the resultant form after the address period, the wall‐charge model after the address period was recently added and the entire wall‐charge model was completed in this work. In addition, by investigating the trajectory of the cell‐state movement during the reset period, it was confirmed that the priming effect affected the reduced discharge time lag of an ACPDP with an auxiliary electrode under the newly proposed driving waveform for reducing address time lag.     

The improvement of the driving waveform for high-speed addressing

A high-speed driving technology is currently one of the most observed technologies in the driving AC-PDP. This is a required technology that allows a high image quality. In this paper, we will propose the new driving waveform which has varied V_scan voltage in the same sub-field for the high-speed driving. Therefore, we were obtained 39.5 V as the minimum V_data voltage at the scan pulse width of 0.8 μs, when the newly proposed driving waveform was applied to a 4-in. test panel. This result was that the minimum V_data voltage decreased by 14.5 V from the conventional driving waveform.     

用于压电换能器的频率跟踪驱动电路设计

针对新的压电换能器损耗模型理论,设计并实现了跟踪最佳驱动频率的驱动电路。通过测量验证了最佳频率工作点的存在;利用LC滤波电路克服了电流振荡波形引起的干扰;对换能器进行阻抗匹配设计;通过数字锁相电路,结合FPGA多线程工作模式,实现了最佳频率跟踪。实验结果,在新的频率跟踪系统下,换能器的发热量降低为原来的一半,相较于定频系统运行更加稳定。     

Address pulses during sustain period for increasing luminous efficiency

Abstract— A new driving method using a short pulse applied to the address electrode (i.e., address pulse) during a sustain period is proposed to improve the luminous efficiency. In this method, short pulses are additionally applied to the address electrode during the rising or falling edge of the sustain pulses. In the case of a small sustain gap, address pulses synchronized with a rising edge of the sustain pulse can help the expansion of the discharge volume toward the address electrode, whereas address pulses synchronized with a falling edge of the sustain pulse produce a self‐erasing discharge, which improves the luminous efficiency. In the case of a large sustain gap, the application of the address pulse can produce a stable sustain discharge at a low sustain voltage level, generating an efficient discharge even in the case of the long discharge path.     

Improvement of display performance of electrowetting displays by optimized waveforms and error diffusion

The electrowetting display (EWD) has a low gray level, and there are some phenomena that affect the display quality, such as oil backflow and charge trapping. In this paper, an error diffusion algorithm based on pixel neighborhood gray information and direct current (DC)‐balanced driving waveform are proposed for display quality of EWD. The proposed algorithm and driving waveform are implemented in the proposed driving system based on Digital Visual Interface (DVI) video codec system and field‐programmable gate array (FPGA) control system. The experiment results show that the driving waveform suppresses the oil backflow, charge trapping and keeps DC balance, and the proposed error diffusion preserves the edges and richness of image. The whole driving system successfully plays video in real time with computer and improves the display quality of EWD.     

An adaptive generation method for electrophoretic display driving waveform design

Electrophoretic display (EPD) technology is attractive when used for reading devices such as e‐paper because of its paper‐like appearance. EPD driving is more complex than other display technologies such as liquid crystal display or organic light emission diode because the driving result of a pixel strongly depends on the initial display state. The particle size and distribution in the EPD film may vary, even if the initial state is the same. Therefore, the display devices vary between different manufacturing batches. Furthermore, different display modes such as videos, pictures or documents need different driving waveforms to achieve an optimal result. EPD manufacturers need to build a customized driving waveform for every manufacturing batch. This is very inconvenient if new applications on EPD are to be developed. And the workload is huge. In this work, an adaptive method is described for automatically creating EPD driving waveforms to fit different conditions. The central idea of this method is generally adjusting the driving time and the voltage state after getting the feedback from a measurement model. In this method, a new driving waveform is used to reduce refresh time and visual flicker. The experimental results show that the proposed approach can automatically and adaptively generate an EPD driving waveform with reasonable quality.     

IC design of driving circuit of MEMS microrobot using pulse-type hardware neuron model

This paper presented a driving circuit which can output a driving waveform of the piezoelectric element impact-type actuator. The piezoelectric element impact-type actuator generates the rotational movement which is necessary to move the legs of the micro electro mechanical systems (MEMS) microrobot. The MEMS microrobot is made from silicon wafers fabricated by micro fabrication technology. The size of the fabricated MEMS microrobot is 4.0 mm × 4.6 mm × 3.6 mm. The driving circuit consists of a bare chip IC of the pulse-type hardware neuron model (P-HNM) and a peripheral circuit. P-HNM is an electrical oscillating model which has the same basic features of biological neurons. Therefore, P-HNM can output the driving waveform of the piezoelectric element impact-type actuator using electrical oscillation as biological neuron. As a result, we showed that the driving circuit can output the driving waveform of the piezoelectric element impact-type actuator without using any software programs or analog digital converters.     

基于单片机的步进电机细分控制系统

步进电机细分技术主要用于提高电机的运转精度,实现步进电机步距角的高精度细分。通过对步进电机细分驱动原理的分析,合理选择细分电流波形,以AT89C51单片机为核心,结合步进电机驱动芯片L 297/298,设计出步进电机的斩波恒流细分驱动控制系统。并在实际运行过程中运行良好。     

Application of AC plasma display panels to radiation detectors

Radiation detector proposals that use plasma display panels are rare. In this work, we confirmed a radiation detector that uses plasma display panels that are focused on the breakdown voltage shift in the ramp waveform. We adapted the cell structures, gas contents, and waveforms of plasma display panels (AC‐PDPs) for radiation detectors. Hard X‐rays and gamma rays induce electron emission into the discharge gas, resulting in generating electrons, electron multiplication, and charge accumulation on dielectrics. The radiation dose rate of hard X‐rays and gamma rays (Cs137) is measured as a breakdown voltage shift between anodes and cathodes. For gamma rays, the detection sensitivity in this experiment is not as high as in the case of hard X‐rays, but the detector can locate gamma rays. These results suggest that adapted AC‐PDPs can detect both hard X‐rays and gamma rays and can be used in a large two‐dimensional radiation detector.     

基于KA962的IGBT驱动电路设计

针对工业中IGBT驱动电路复杂、设计困难等情况,通过对KA962芯片的研究,使用其作为主要的驱动模块,设计了种方便、实用的IGBT驱动电路,并且说明了各部分电路的设计要求及作用.最终通过实验表明,这种驱动电路能够驱动相应的IGBT模块,并产生符合工作要求的波形,从而验证了本设计的可行性.