模拟发电机组专用可控硅直流调速系统

本文从分析同步发电机原动系统基本数学模型入手，提出了一种实现同步发电机原动系统仿真的专用可控硅直流调速系统及其实用装置。该控制系统采用有差调节的模拟调速器，水汽管道特性模拟、自平衡特性模拟和集成块模拟触发器，以及过流与超速保护，并可实现有差－无差调节的转换。     

Carrying Capacity of Stretching-bending Rectifier

In accordance with the deficient elongation of the Stretching-bending Rectifier, as well as the severe wear and slipping of V-belt , the driving system velocity ratio of rectifier and the calculation formula of the theoretical elongation are deduced, which are based on the analysis of its structure and reeling principle. The carrying capacity of the driving system is also analyzed and it reaches the main reason for the elongation of the stretching-bending rectifier that cannot reach request, which is caused by the step less torsion of fixed output of the continuously variable transmission. The improvement measure which can be achieved by increasing the stiffness of the spring to increase the output torsion of the continuously variable transmission is proposed. Thus it makes the actual coefficient of elongation,which can satisfiy the producing request.     

一种具有谐波抑制和无功补偿功能的新型整流变换器

研究了一种具有谐波抑制和无功补偿功能的新型PWM整流变换器,详细地讨论了整流器谐波与无功参考电流的提取和整流器输出电压的控制．采用基于瞬时无功理论的廿iq电流检测算法分别给定谐波和无功参考电流．为了有效地补偿电网中的谐波及无功电流,提出了一种电流和电压双闭环控制策略,其中,直流侧电压的调节采用模糊PI混合控制．最后,基于PSIM的仿真实验验证了不同工作模式下该方法具有良好的电压调节特性和谐波与无功补偿效果．     

发电机原动系统仿真器程序设计

研制了一种新型的基于80C196KC单片机的原动机仿真系统的软件．对系统中的调速器，利用灵活的单片机的软件去实现其功能，不仅使硬件线路大为简化，并且克服了模拟电路结构复杂、电子元器件容易老化、易受环境温度影响和抗干扰能力差等缺点，提高了整个系统的控制精度、可靠性和稳定性．此外还设置了液晶显示器和人机通讯接口，可将原动机仿真系统的运行参数以数字信号的形式传输到监控系统或者PC机，操作直观、便于监视．微机软件编写采用了模块化，使软件的编写更方便、简单，软件已完全通过调试，达到了预期的效果。     

匀浆辊流浆箱中匀浆辊的波迹效应

匀浆辊流浆箱以转动的孔辊作为匀整元件 ,匀整浆料的流速 ,具有整流和分散纤维的作用 .该文主要讨论波迹效应对匀浆辊设计的影响 ;匀浆辊流浆箱的匀浆辊 (闸辊 )的波迹效应产生的纤维定向条纹 ,导致整流效果不良 ,最终引起涂布、压光中的纸病 ,影响印刷质量 .经分析 ,这种波迹效应引起的纤维定向条纹 ,不同于简单的定量条纹 ,改变匀浆辊的运行参数、几何参数并不能消除 .匀浆辊的转动 ,必然产生哪怕纵向上轻微的涡流 ,就不可避免产生定向问题 .因此 ,匀浆辊流浆箱只适用于中低速纸机 .     

爪极式无刷硅整流发电机的负载特性分析

本文简单介绍爪极式无刷硅整流发电机的构造和负载特性曲线,着重分析外特性曲线并论证发电机限流作用的条件和范围。本文导出了发电机整流线路在空载和负载状态下输出直流工作电压的计算公式。     

Design of wireless inductive power receiver circuit in artificial subretinal chip

A scheme of inductive wireless receiver circuit is put forward, according to special requirement of inductive wireless power supply in artificial subretinal prosthesis circuit. The proposed receiver circuit can be divided into CMOS rectifier, regulator and self-biasing circuit. The CMOS rectifier is used to provide power supply for regulator and self-biasing circuit. The self-biasing circuit furnishes the regulator with bias voltage and bias current which is independent from power supply. The proposed receiver circuit is designed by Cadence tool and Chartered 0.35 μm CMOS device model, and oscillator in artificial subretinal chip is used as the proposed receiver circuit’s load. The results show that the proposed receiver circuit can provide load capacity of 3.3 V and >1 mA,with a layout size of 62 μm×195 μm.     

带双负载运行的VIENNA整流器中点电压平衡控制

针对VIENNA整流器结构固有的中点电压波动问题,可以通过双负载结构中调整负载的大小来观察。文章分析了三相VIENNA整流器的工作原理,采用一种电压电流双环结构,空间矢量调制(SVPWM)方式控制运行。针对三电平结构固有中点电压波动问题,通过调节正负小矢量的作用时间,能够达到双负载在大小不同的情况下,直流电压稳定,中点电压平衡的效果,最后使用MATLAB/Simulink仿真证明了此方案的可行性。     

Effect of breviscapin on Ito and IK1 channel current in isolated ventricular myocytes of rats

AIM: The effects of breviscapin on transient outward potassium current (I_to) and inward rectifier potassium current (I_K1) channel in isolated ventricular myocytes of rats were determined. The mechanism of breviscapin at the ionic channel level was explored. METHODS: Single ventricular myocyte of rats was isolated by enzymatic dissociation. The whole-cell patch-clamp recording technique was used to record the change of I_to and I_K1 channel current influenced by breviscapin. RESULTS: Breviscapin decreased the I_to channel current in a dose-dependent and voltage-dependent manner in ventricular myocytes of rats. (1) The current-voltage curve was significantly decreased. Breviscapin at concentrations of 0.02, 0.05, 0.08, 0.10 g·L^-1 respectively decreased I_to current density (10.07±0.50)%, (27.47±2.36)%, (42.72%±2.50)% and (56.09±5.60)%. I_to was inhibited in a voltage-dependent manner, showing a significant attenuating effect at test potentials from 0 to + 50 mV. (2) The I_to activation curve, the activation curve and the recovery curve were not altered. (3) Breviscapin did not affect I_K1. CONCLUSION: Breviscapin concentration-dependently decreases I_to channel current in ventricular myocytes of rat.     

尾水管加装整流筒后对其内部流态的影响

通过在尾水管的通道内设有前后两端开口的整流筒,利用CFD技术对典型工况进行了对比模拟研究,探究了加装整流筒前后对尾水管内部流态的影响.研究结果表明,在典型工况下,尾水管出口断面的压力分布相对比较均匀,整流筒直径为1.05D₁时,压力升高最明显.计算了在不同条件下尾水管整流筒进口断面位置中心到壁面静压分布、整体轴中心截面压力分布以及监测了尾水管整流筒在进口处断面壁面上记录点的压力脉动随时间的变化情况.研究显示:整流筒直径为1.05D₁时对改善尾水管内部压力场分布和抑制空化带来的影响起到了积极作用,安装整流筒的尾水管中轴面压力梯度减小,在尾水管的进口截面旋涡分散且数量减少,同时减小了中轴心与尾水管壁面的压差,尾水管的流场稳定性增加.