陡脉冲发生器电路中杂散参数的分析和补偿

在陡脉冲发生器电路中,杂散参数不仅影响输出波形,还影响着系统的稳定和电路元器件的安全.为了提高输出波形的质量,抑制输出脉冲的振荡,保证元器件长期可靠的运行,需要对电路中杂散参数进行有效的分析和补偿.本文通过对脉冲的实际输出波形进行分析,建立了陡脉冲发生器电路的杂散参数模型,总结出一种分析和补偿陡脉冲发生器电路中杂散参数的方法.模型的仿真结果精确地反映了实际波形,加入补偿环节后的电路实现了输出波形的无过冲.      

性价比极高的全晶体管OCL功放电路制作

OTL功放电路省去了输出变压器,OCL型功放电路又进一步省去了输出耦合电容.无论是在频率响应还是在非线性失真上,都比OTL功放电路有更大的改善,这是由于去掉了耦合电容,改善了低频响应.因为耦合电容对音频信号的容抗与频率成反比关系,频率越低容抗越大,这就使低频响应受到限制.OCL功放电路必须采用正负对称电源供电,全电路用直接耦合的方式,因此电路的零点漂移较为严重,为降低零点漂移,OCL电路的输入级往往采用了差动放大电路.     

PID控制及高频逆变技术的X射线机电源

针对目前的X射线机控制精度不高以及稳定性不够的问题,介绍了一种数字化的X射线机电源,其中调压电路采用BUCK电路的改进形式,高压发生的重点部分采用高频逆变以及软开关技术,使最重要的逆变环节输出稳定.调压电路以及逆变电路中开关管的控制采用PWM控制技术,驱动波形输出稳定且容易控制.反馈电路由单片机的软件PID来控制,提高了高压的控制精度并减小了体积,而且实现了高压的连续可调.灯丝电源采用高精度的电源芯片,实现了灯丝电流的稳定.通过对电路的分析,计算出了电路所用参数并用PSPICE软件进行了仿真.最后的仿真结果表明,理论分析结果与实际的结果一致,设计的电源系统可以稳定运行,达到了X射线机所用电源的指标要求.     

交流电弧炉三相不平衡供电的研究

提出了三相操作电抗随无量纲电流变化的三相交流电弧炉电路模型,进而给出了适用于三相电流不对称,电压不对称和阻抗不对称情况的计算模型。基于上述三相交流电弧炉电路模型,分析了电流不对称和阻抗不对称对电弧功率的影响,并讨论了交流电弧炉三相电参数互相影响的复杂性。依据本模型可灵活实现三相交流电弧炉的平衡和不平衡供电,进而改善电弧炉的电气运行特性。     

专利介绍

CN1292427铝合金熔体除氢旋转脉冲喷吹装置铝合金熔体除氢旋转脉冲喷吹装置由气路供应系统、电气控制系统、石墨转杆转头、坩埚组成,气路供应系统中增设减压阀和电磁阀,减压阀和电磁阀并联联接在气路供应系统的压力表(一)之后和压力表(二)之前,在电气控制系统中增设脉冲输出电路,低压稳压电源与脉冲输出电路相联接,脉冲输出电路与电磁阀相联接。CN1287098一种提高氢氧化铝种分分解率的添加剂及用法本发明是一种在铝酸钠溶液种分分解中应用的添加剂,以及该添加剂的应用方法。该添加剂为含有0.5‰～20‰的聚丙烯酸钠和聚丙烯酰胺的组合物的…     

应用于无线传感网频率合成器的0.5V低电压鉴频鉴相器设计

基于0.13μm CMOS技术设计了一个应用于无线传感网频率合成器、电源电压为0.5 V的鉴频鉴相器.它的功能是比较输入信号的频率和相位差,并输出一个与该差值成比例的电压.因电源电压是0.5 V,所以该电路采用低阈值晶体管.为了增大相位误差的检测范围和提高最大工作频率,该电路采用了脉冲锁存的结构.当输入信号频率为2 MHz时,测得的相位误差检测范围为-358°～358°.与传统数字鉴频鉴相器相比,该电路具有较快的捕获速度.当输入信号的频率为2 MHz且相位误差为0°时,电路的功耗为1.8μW,并且最大工作频率为1.25 GHz.     

高频链矩阵式变换器前级包络线SPWM调制技术

为了减少高频链矩阵式变换器输出波形的谐波成分获得更好的波形质量,提出了一种包络线调制方法.此方法与解结耦SPWM调制相结合,使得高频链矩阵式变换器的前级驱动信号的占空比规律性变化.前级电路的调制波不采用普通直流电压,而是采用没有滤波时的三相桥式整流电路的输出电压,前级逆变的驱动信号的占空比随着三相电压的包络线变化而变化.通过使用该技术,高频链矩阵式逆变器的三相输出电压波形质量优于只使用SPWM调制方法的三相输出电压.文章介绍了调制技术的工作原理和电路的工作过程,使用PSpice进行了仿真,仿真结果表明这种调制方法是可行和有效的.     

自制波形发生器的设计与实现

本文设计了一款基于H2C20-V5型SOPC的自制波形发生器,采用触摸屏实现输入和显示同屏进行,波形数据的函数计算形式与基于FPGA的DDS方案结合,并采用简单易行的电平平移电路,实现宽电压范围的波形输出.该波形发生器具有操作界面简捷直观、调试灵活、波形发生速度快等特点,能够满足基础电学实验室的应用要求.     

基于摆幅恢复传输管逻辑的高性能全加器设计

为了降低硬件开销，越来越多的加法器电路采用传输管逻辑来减少晶体管数量，同时导致阈值损失、性能降低等问题。本文通过对摆幅恢复逻辑与全加器电路的研究，提出一种基于摆幅恢复传输管逻辑（Swing restored pass transistor logic, SRPL）的全加器设计方案。该方案首先分析电路的阈值损失机理，结合晶体管传输高、低电平的特性，提出一种摆幅恢复传输管逻辑的设计方法；然后，采用对称结构设计无延时偏差输出的异或/同或电路，利用MOS管补偿阈值损失的方式，实现异或/同或电路的全摆幅输出；最后，将异或/同或电路融合于全加器结构，结合4T XOR求和电路与改进的传输门进位电路实现摆幅恢复的高性能全加器。在TSMC 65 nm工艺下，本文采用HSPICE仿真验证所设计的逻辑功能，与文献相比延时降低10.8%，功耗延时积（Power-delay product, PDP）减少13.5%以上。      

汽车点火系统传导电磁干扰仿真

汽车点火系统工作时产生的电磁干扰具有能量大,频带宽等特点,被认为是汽车电磁兼容最主要的电磁干扰源.笔者提出了一种预测点火系统传导电磁干扰模型建立方法:建立系统中每个部件的电路模型,利用测量、解析法或有限元方法确定模型中的分布参数,集成为点火系统等效电路模型进行系统仿真计算.时域与频域实验测试结果证实了该模型的正确性与方法的可行性.     

High-efficiency shock-wave generator for extracorporeal lithotripsy

In extracorporeal lithotripsy, the electro-acoustic efficiency of electrohydraulic generators is limited by the inductance of the electrical discharge circuit. A new shock-wave generator is described that uses a coaxial discharge line enabling electro-acoustic efficiency to be greatly increased. The line is built using a para-electric ceramic with a relative dielectric constant of 1700, manufactured for use in high-voltage impulse mode. A coaxial spark gap, with minimal inductance, has been developed to obtain the triggered breakdown of the discharge line. Shock waves are created with a coaxial electrode plugged directly into the spark gap and immersed in an electrolyte of degassed saline. Electrode gap and electrolyte resistivity are adjusted to match the resistivity of the electrolyte volume between the underwater electrodes to the characteristic impedance of the line. The discharge line generates in the medium a rectangular current pulse with an amplitude of about 6000 A and a rise time of 50 ns. Compared with conventional generators, measurements of the expansive peak pressure pulse show an increase of 105% at 10 kV, 86.5% at 12 kV and 34.5% at 14 kV charging voltage. Electro-acoustic efficiency is found to be 11% instead of 5.5% for a conventional discharge circuit.     

Electrostimulated machining of metals

New mechanical equipment requires structural materials whose high performance cannot be ensured by traditional methods. A promising approach to the shaping of steel is the use of powerful unipolar current pulses with the following characteristics: amplitude 10–15 kA; pulse frequency up to 400 Hz; pulse length up to 100 μs. The widespread industrial use of this technique is hindered by the low efficiency of the corresponding pulse generators, which also draw considerable power from the ac grid and are not sufficiently controllable. In the present work, a generator of powerful unipolar current pulses that is free of those defects is described. It includes a charging system connected to power capacitors; and a thyristor switch that discharges the capacitors to a low-resistance load. To reduce the power drawn from the grid, the generator includes a recharging device based on a thyristor, which is connected to a reverse-parallel thyristor switch. To permit regulation of the pulse amplitude and increase its power, the uncontrollable dc source in the charging system is replaced by two irreversible thyristor converters in series. That permits control of the voltage at the power capacitors. To optimize capacitor charging, a two-loop subordinate control system regulates the parameters of the pulse generator: the external control loop governs the voltage charging the capacitors, while the internal control loop governs the charging current. MATLAB Simulink software is used to create a model of the proposed generator. The model corresponds to the actual pulse generator used at Siberian State Industrial University to investigate the electrostimulated plastic deformation of metals and alloys. The model permits improvement in the characteristics of the pulse generator and its operating conditions. A benefit of the proposed generator over its counterparts is that the power drawn from the grid is considerably reduced, while the voltage charging the capacitor may be regulated in the range up to 600 V, with pulse frequencies up to 400 Hz. The generator may be used industrially—in particular, in rolling mills when drawing steel wire that is hard to deform.     

Reduction of stomach ulceration by hypothalamic stimulation in the unrestrained rat

A rechargeable demand pulse generator for permanent transvenous cardiac pacing was evaluated in 66 patients. During a cumulative follow-up period of 895 patient months there was no instance of failure of either the pulse generator or of the recharging circuit. Acceptance of the recharging concept was high, there being only one patient in whom it was necessary to replace the rechargeable generator because of inability to master the recharging technique. The early findings indicate that with proper patient selection the rechargeable pulse generator promises to be an important contribution to pacemaker therapy.     

Pacemaker therapy in premature children with high degree AV block

The smallest pacemaker pulse generator and a steroid-eluting bipolar epicardial lead were implanted in two premature children with symptomatic AV block. Stable capture threshold and high amplitude evoked response electrogram resulted in normal function of the pacemaker Autocapture algorithm, which adjusts output 0.3 V above the measured capture threshold. Autocapture had previously been used only with endocardial leads. Longer-term observation is required.     

山东省冶金工业利用余能发电设备建设和运行情况

介绍了山东冶金工业利用余能发电的设备建设和运行情况及特点。在已建成的59台发电机组中,大多数是利用富余煤气、余热和余压,能源利用形式多样,装机容量不断增加,单机容量也在不断增大,发电量不断提高,发、用电量比例有明显提高。但存在装机品种多、小容量比例多、发展不平衡等问题。同时提出,国家有关部门应对富余能源综合利用给予政策和资金上的支持,企业应统筹规划,进一步做好余能的回收和利用等方面的工作。     

丰田叉车发电机调节器工作原理及诊断

汽车发电机调节器由最早的机械触点式、晶体管式、到现在的集成电路和微机控制式.无不表明社会在发展,科技在进步.我们必须紧跟其脚步,自主积极的去攻坚克难!丰田叉车发电机电子调节器是通过检测蓄电池电压来调节发电机的输出电压,必须分清调节器上各连接线束的功用及其原理.     

1D Time-Domain Solution for Seismic Ground Motion Prediction

A full time-domain solution for predicting earthquake ground motion based on the 1D viscoelastic shear-wave equation is presented. The derivation results in a time-domain equation in the form of an infinite impulse response filter. A solution in the time domain has several advantages including causality, direct modeling of impulsive and transient processes, and ease of inclusion of nonlinear soil behavior. The method is applicable to any arbitrarily layered silhouette presented as SH-wave velocity, damping coefficient, and mass density profiles for designated soil intervals. For nonlinear evaluations, an equivalent-linear formulation is incorporated and the standard modulus and damping degradation curves become part of the input set. Input motion can be either rock-outcrop or body-wave motions measured or estimated at the bottom of the geologic profile, and the output is the estimated ground motion time history. Application of the method to vertical array strong motion records from Garner Valley, and Wildlife Site, Calif., shows that predicted surface (and interval) ground motion is virtually identical to that measured. The differences between the results of linear and nonlinear analyses are negligible for most cases. A comparison of the time-domain model with SHAKE shows that SHAKE fails to accurately predict time histories in some situations, whereas the time-domain solution always yields satisfactory predicted surface ground motions.     

Self-stimulation in the rat: Quantitative characteristics of the reward pathway.

Quantitative characteristics of the neural pathway that carries the reinforcing signal in electrical self-stimulation of the male Sprague-Dawley rat's brain were established by finding which combinations of stimulation parameters give the same performance in a runway. The reward for each run was a train of evenly spaced monophasic cathodal pulses from a monopolar electrode. With train duration and pulse frequency held constant, the required current was a hyperbolic function of pulse duration, with chronaxie c?=?1.5 msec. With pulse duration held constant, the required strength of the train (the charge delivered per second) was a hyperbolic function of train duration, with chronaxie C?=?500 msec. To a first approximation, the values of c and C were independent of the choice either of train duration and pulse frequency or of pulse duration, respectively. Hence, the current intensity required by any choice of train duration, pulse frequency, and pulse duration depended on only 2 basic parameters, c and C, and 1 quantity, Qi, the required impulse charge. These may reflect, respectively, current integration by directly excited neurons; temporal integration of neural activity by synaptic processes in a neural network; and the peak of the impulse response of the network, assuming that the network has linear dynamics and that the reward depends on the peak of the output of the network. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Heart pacemaker with lithium batteries. 2 years' clinical experience

102 lithium-powered cardiac pacemakers manufactured by Cardiac Pacemakers Inc. (CPI 301 UD, 101 UA and 501 UD) were implanted in 94 patients. During the observation time (25 months) the following complications were registered: 2 pulse generator failures, 4 failures of the demand-function, anodic muscle-twitching in 2 patients, 2 erosions of the pacemaker-pocket and 1 hematoma of the pocket. 5 pulse generators were exchanged without malfunction of the pacemaker. In 4 patients reinterventions on the electrode had, to be performed. 4 deaths occurred, none of them related to malfunction of the pacemaker. 2 lithium-powered pacemakers were explanted in other hospitals, for reasons not known to us and 1 patient left the German Federal Republic. 83 patients are under control with well working lithium-powered pacemakers.