用于压电作动器的无源可控电抗器

为实现压电作动器动态无功补偿的目的,该文提出了一种基于变压器的无源可控电抗器的新方案。通过对变压器T型等效电路的端口等效阻抗方程分析可知,当变压器负载阻抗变化时,变压器的等效并联感抗会发生变化,从而实现变压器一次侧阻抗可调。增加变压器原副边电感值,可增加变压器的等效并联电阻,从而减小可控电抗器损耗。理论和实验结果证明此新方案的正确性。     

周期性温度激励对MGDL混合性能及小信号增益系数的影响

将基于周期性温度激励的主动控制技术引入混合型气动CO2激光器（MGDL）研究,通过数值计算深入研究了周期性温度激励对MGDL主/副气流混合特性及小信号增益系数的影响。研究结果表明:与未施加周期性温度激励的情形相比,在MGDL副喷管出口位置施加特定幅值及特定频率的周期性温度激励后,可以显著增强主/副气流的混合效果并大幅提高混合喷管中的小信号增益系数。激励幅值和激励频率对主/副气流混合特性及小信号增益系数有重要影响:随着激励幅值的增加,小信号增益系数先增大后减小;在混合喷管下游区域,文中所选的六种激励频率条件下获得的小信号增益系数均高于未施加周期性温度激励时的情形;随着激励频率的增加,主/副气流的混合效果越来越好,但当激励频率增加到一定值后,主/副气流的混合效果不再发生变化。     

音频变压器环形磁芯优于EI磁芯

随着数字音频设备的日益普及,音频变压器市场已开始下降,新型的电视接收机现已采用IC进行信号处理。音频设备领域的制造商也在探索数字电路和模拟电路耦合方案。但是,在高档音频设备领域,模拟元件正在复辟,音频变压器在高保真系统中已确立了它的地位。     

基于用电信息采集系统校核运行变压器容量的方法

通过对不同变压器型号和容量的铭牌参数分析对比,找出规律,利用用电信息采集系统平台对运行中的变压器有功空载损耗和无功空载损耗数据采集,并和运行变压器实际铭牌相关参数进行对比,通过计算分析,能够对该变压器的实际运行容量进行校核,从而初步判定实际运行变压器容量与营销系统档案资料数据的一致性,为供电企业用电检查工作提供参考依据.     

音频信号发生器的制作

音频信号发生器是测量放大器的输入输出阻抗和放大电路的特性时,不可缺少的测量仪器。这里介绍一款制作容易,元器件容易购买,成功率高的音频信号发生器。该发生器的频率选择不是连续式的,而是点式的。设计电路时,在增加频率点的数目的同时,     

宽带变压器在压电陶瓷驱动电源中的应用

受高压功率器件的限制,目前市场上压电陶瓷高压驱动电源较少且价格贵。变压器能够实现电压和电流的变换,合理的设计可使其在较宽的频率范围内保持良好的频率响应特性。该文研究了一种基于音频变压器的压电陶瓷高压驱动电源的实现方式,并进行了相关实验,实现了一种空载时-3 dB带宽达4 Hz~380 kHz、输出电压峰 峰值达600 V的驱动电源,可在20 kHz的频率下满负荷驱动2.5 nF的容性负载。     

浅析调容变与子母变的应用

<正>农村用电负荷有着明显的季节性,一般最高负荷都出现在春节期间,农户会集中用电,在这种状况下,用电高峰季时与用电淡季是相差很大,高峰季时变压器过载运行严重,而在淡季是也现了"大马拉小车"的现象,造成变压器空载损耗严重,这给选择变压器容量带来了困难。按大负荷选择。变压器运行不经济,按小容量选择,高峰季节会出现设备烧坏现象,造成不必要的经济损失,为了合理选择配电变压器容量,提升10kV配电变压器的供电能力,公司推出调容     

变压器新差动保护技术研究

变压器保护主要有瓦斯保护和纵联差动保护,纵差动是变压器必须采用的保护原理。可以反映变压器的各种内部相间和接地故障。文章提出了一种不受空投时励磁涌流影响的新方法,用阻抗继电器反应空投于内部故障．这种保护配置方式在内部故障时有很高的灵敏度,在外部故障时又有很强的制动作用,不反映空投时的励磁涌流．却能反映变压器空载合闸时有故障的情况．解决了变压器差动保护的难题。     

用放大器还是用变压器驱动ADC?(下)

<正> 问:变压器的重要特性是什么?答:变压器有许多特性,如电压增益和阻抗比、带宽和插入损耗、幅度和相位不平衡性,以及回波损耗。其它特性可能包括额定功率、配置类型和中心点选项。使用变压器进行设计并不总是一帆风顺的。例如,变压器的特性会随着频率变化,从而使变压器模型复杂化。在 ADC 应用中开始变压器建模的一个例子如图6所示。每一个参数都取决于所选用的变压器。变压器特性包括:匝数比、电流比、阻抗比插入损耗、回波损耗、幅度失衡和相失衡等。匝数比是次级电压与初级电压之比。电流比与匝数比成反比。阻抗比是匝数比的平方。信号增益正好等于匝数比。尽管电压增益无噪声,但是要考虑其它因素。变压器可以简单地看作具有标称增益的带通滤波器。插入损耗是滤波器在规定频率范围内的损耗,虽然它是产品使用说明中最常见的测量技术指标,但还要考虑其它指标。回波损耗是指从变压器的初级端看次级端有效阻抗不匹配特性的一种度量。例如,如     

基于盘型对称驱动的惯性冲击旋转压电马达

该文提出了一种基于盘型对称驱动的惯性冲击旋转压电马达。该马达主要由定子、转子、驱动足和预紧装置组成。马达激励信号为锯齿波信号,采用压电叠堆激励实现马达高功率输出。马达通过螺杆将定子与预紧装置装配于一体,实现了马达结构紧凑化与微型化。设计加工了马达样机并通过实验验证了马达的工作原理,对马达的综合性能进行了分析和测试。测试结果表明,当马达预紧装置施加的预紧力为1 N,输入激励电压峰-峰值为80 V,激励信号频率为1 kHz,且每输出一个周期锯齿波,激励信号延迟100 ms再输出下一个,以研究马达静态启动特性和步长,测得马达的最大空载速度达到3.05 r/min,平均步长为0.032 rad;激励信号频率为3 kHz时,马达的最大空载速度达到9.1 r/min,马达最大负载可达16.2 N·mm;马达在0.5~3 kHz激励信号频率范围内均可实现转动。     

Semiconductor tuning circuit having constant Q over a wide range

A new type of variable tuning circuit using semiconductor inductance is described. This tuning circuit has a constant Q value over a wide range of frequency. Semiconductor inductance in this circuit is obtained using the impedance conversion method, however, there is no instability such as with negative impedance converter (NIC) and the structure of the circuit is simple. The common fault of semiconductor inductances is that their input impedance changes according to frequency, causing the Q value to vary widely. An attempt to solve this fault by the addition of a second ganged capacitor was made. Experimental results prove the validity of the theory, and confirm that this tuning circuit has practical applications. Applications of this circuit are shown at the end of this paper.     

LC PLL With 1.2-Octave Locking Range Based on Mutual-Inductance Switching in 45-nm SOI CMOS

A wideband LC PLL in 45-nm SOI CMOS technology is presented that has a center frequency of 12.4 GHz and 1.2 octave locking range. The wideband operation is achieved by switching mutual inductances within the inductor coil of the LC oscillator. To minimize resistive switching losses, the inductor coil consists of a non-switchable primary coil and two isolated secondary coils with series switches. When the switches are closed, the overall inductance reduces because of the switched mutual inductances. Three inductor bands, each consisting of 16 switched capacitor sub-bands, span a frequency range from 7.3 to 17.5 GHz. The in-band phase noise measured after a 1/4 divider is better than ${-}$107 dBc/Hz at 1 MHz offset frequency in the entire locking range. The PLL is fully differential and its core has a power consumption of 25 mW at the highest oscillation frequency.      

Microwave Group Delay Time Adjuster Using Parallel Resonator

This letter describes the design of a group delay time adjuster (GDTA) using a parallel resonator. The GDTA consists of a variable capacitor and a variable equivalent inductor. These components are controlled by two bias voltages separately. The variable equivalent inductor is realized using a high impedance transmission line terminated with the variable capacitor. Group delay time can be adjusted by varying the capacitance and the inductance while keeping the fixed resonance frequency. When the proposed GDTA is fabricated on the Korean RFID frequency band (908.5-914MHz), we could obtain about 3ns group delay time variation with excellent flatness     

一种数字控制电感测量仪的设计与实现

设计了一个以芯片STM32F407ZGT6为控制核心的数字式电感测量仪,可以对正弦信号源、电感Q值以及电感值实现精确测量。系统硬件电路主要由电源供电电路、信号产生电路、信号调理、测量电路、数据采集与处理以及人机交互等模块组成,其中信号调理电路采用高速运放进行放大和阻抗变换,调节信号幅度的同时保证各级的输入输出阻抗,以达到最高的测量精度。测量电路采用谐振法测量回路谐振频率,然后用伏安法测量可变电容当前值,再通过谐振频率和电容值计算得到被测电感的Q值和电感值。最后经过测试,系统实现了输出范围达50～40MHz 的正弦信号源,测量误差优于0.1%,并且对电感Q值和电感值的测量误差均小于3%。     

基于阻尼振荡法的甚低频天线阻抗测量

为了准确测量甚低频发射天线在实际工作环境和工作频点上的输入阻抗,本文提出了一种基于RLC阻尼振荡法的阻抗测量方法,并推导了天线阻抗、电容、电感和电阻的测量公式;该测量方法可通过提高测量电压来提高测量信噪比和测量精度;测量系统谐振于被测天线的工作频点或其附近,使甚低频发射天线输入阻抗的测量值更接近天线在实际工况下的真实值.试验表明,本文提出的测量方法简单可行,具有较高的精度和稳定性,可实现甚低频发射天线输入阻抗的现场测量.     

A readout system for passive pressure sensors

This paper presents a readout system for the passive pressure sensors which consist of a pressure- sensitive capacitor and an inductance coil to form an LC circuit. The LC circuit transforms the pressure variation into the LC resonant frequency shift. The proposed system is composed of a reader antenna inductively coupled to the sensor inductor, a measurement circuit, and a PC post-processing unit. The measurement circuit generates a DC output voltage related to the sensor＇s resonant frequency and converts the output voltage into digital form. The PC post-processing unit processes the digital data and calculates the sensor＇s resonant frequency. To test the performance of the readout system, a sensor is designed and fabricated based on low temperature co-fired ceramic （LTCC）, and a series of testing experiments is carried out. The experimental results show good agreement with the impedance analyzer＇s results, their error is less than 2.5%, and the measured values are almost insensitive to the variation of readout distance. It proves that the proposed system is effective practically.     

Cyclostationarity-based model for noise analysis of charge amplification with correlated double sampling

A lossless floating inductance has been simulated using two differential voltage current conveyors, two resistors and one grounded capacitor. The proposed floating inductance needs not component matching condition. Base on the proposed floating inductance as building block, a new voltage-mode universal biquadratic filter with one input and five outputs can be obtained. The proposed universal biquad uses two differential voltage current conveyors, three resistors and two grounded capacitors. All standard filter functions; highpass, bandpass, lowpass, notch and allpass can be obtained, simultaneously, without changing the passive elements. The proposed universal biquad has the features of using only grounded capacitors and orthogonal controllable of resonance angular frequency and quality factor.     

谐振法测量脉冲电容器分布电感的原理和方法

本文介绍了用谐振法测量脉冲电容器分布电感的基本原理和测试方法.经适当变换后,还可以测量电感线圈的分布电容.     

Series resonant converter with auxiliary winding turns: analysis,design and implementation

Conventional series resonant converters have researched and applied for high-efficiency power units due to the benefit of its low switching losses. The main problems of series resonant converters are wide frequency variation and high circulating current. Thus, resonant converter is limited at narrow input voltage range and large input capacitor is normally adopted in commercial power units to provide the minimum hold-up time requirement when AC power is off. To overcome these problems, the resonant converter with auxiliary secondary windings are presented in this paper to achieve high voltage gain at low input voltage case such as hold-up time duration when utility power is off. Since the high voltage gain is used at low input voltage cased, the frequency variation of the proposed converter compared to the conventional resonant converter is reduced. Compared to conventional resonant converter, the hold-up time in the proposed converter is more than 40ms. The larger magnetising inductance of transformer is used to reduce the circulating current losses. Finally, a laboratory prototype is constructed and experiments are provided to verify the converter performance.     

Fully Symmetrical Monolithic Transformer (True 1 : 1) for Silicon RFIC

A novel on-chip transformer configuration that gives an identical inductor pair, a higher individual coil self-resonant frequency (SRF), and excellent area efficiency are presented. This technique involves the unique way of inter-crossing the transformer's primary and secondary coils using multiple metallization layers. Truly symmetrical transformer configuration (100%) is demonstrated using minimum die size. Thus, a true 1 : 1 transformer has been realized on silicon. The effects of the parasitic within the transformer are represented by an equivalent-circuit model. Accurate semiempirical expressions describing the circuit components are provided based on the various layout parameters. Of all the transformer structures presented, the two designs occupying the minimum silicon area by a factor of > 2× have been selected for performance evaluation of the SRF, coupling coefficient, input impedance, quality factor, and inductance. The transmission line transformer mode has also been studied to examine the designs' performance in the differential mode. The second proposed design reported in this paper, with enhancements in S21 and k performance, is created by adding a unique routing technique onto the first proposed structure. The method presented is fully compatible with the standard foundry CMOS processes. The silicon data reported in this study are based on chartered semiconductor manufacturing's 0.13-mum RF CMOS technology node.