三相交流电源过零点及相序检测电路设计

基于目前三相交流电源过零点检测电路过零点检测不准确或成本高的问题。文中设计了一种经济实用、过零点检测准确且具有相序检测和缺相检测的电路。由于三相三线制电源没有零线,该电路首先构建了一条零线,使线电压变成相电压,利用比例放大器电路降压,然后使用电压比较器电路产生标准的方波,在交流电的正半周期比较器输出零电平,在交流电的负半周期电压比较器输出高电平。该电路多次应用在晶闸管调压电路中,结果证明该电路具有较高的可靠性和准确性。     

基于电压电流多信息采集的电火防控系统设计

传统的电气火灾防控系统在受到线路分布电容与漏电检测死区的影响时可能会失效或误判。为了提高漏电故障检测和电火防控的速度及准确率,设计开发了一套基于电压电流多信息采集的电火防控系统。系统实时采集相电压与漏电流,通过滑动窗口算法提取其故障特征,进行线性预测后完成故障检测和判断,并驱动故障相的旁路保护模块,提供低阻抗接地通路降低漏电电流,消除线路分布电容对电火防控的影响。系统分别完成了漏电故障的保护效果和保护动作特性测试,均能实现快速、准确的漏电故障保护,保护后的故障相电压低于3 V,漏电电流低于5 mA,保护动作时间不超过15 ms,且输出线电压幅值、相位保持不变。     

基于PLC的电压互感器线电压和相电压的测量

电压互感器是发电厂、变电所等输电和供电系统不可缺少的一种电器。本文运用PLC控制器,设计了一种检测电压互感器的线电压和相电压的方法。     

发电机电子自动并网仪

从所周知,发电机投入电网运行的并网条件是:发电机的电压、频率、相位、相序应和电网的电压、频率、相位、相序相同.大、中型电厂采用同期装置来检查两者的电压、频率、相位和相序.对于6000KW以下的小型电站和商业电站来说,同期装置接线复杂,仪表繁多,购置价格高,采用电子元件制作的发电机自动并网仪,具有结构简单、制作容易、费用低廉的优点,已在各小电站中广泛应用,使用效果良好.     

民用电压对楼道设备的影响

<正>随着互联网的发展,数字电视整改、双向网络的建成,数据通信设备(如楼道交换机、ONU)越来越多,农村地区、用户集居地的"相电压"在用电高峰期都有偏低现象。通常我们在给交接箱、配线箱取电的时候,都是取自楼道、附近电杆上的单相照明电。单交流照明电是指任一相线(火线)与零线之间的电压,也就是220 V,而三相电是电能的一种输送形式,是3个频率相同、振幅相等、相位依次互差120°,3根火线之间的线电压为     

发电机电子自动并网仪

从所周知,发电机投入电网运行的并网条件是: 发电机的电压、频率、相位、相序应和电网的电压、频率、相位、相序相同。大、中型电厂采用同期装置来检查两者的电压、频率、相位和相序。对于6000kW 以下的小型电站和商业电站来说,同期装置接线复杂,仪表繁多,购置价格高,采用电子元件制作的发电机自动并网仪,具有结构简单、制作容易、费用低廉的优点,已在各小电站中广泛应用,使用效果良好。发电机电子光耦合自动并网仪的电路图如附图所示。其原理介绍如下。     

模拟中性点不接地系统发生单相接地故障时电压波形实验电路的设计

该文阐述了中性点不接地系统的优点,分析中性点不接地系统发生单相接地故障时各相电压、电流以及零序分量的理论特征。利用555定时器、低通滤波器以及移相电路设计频率、相位和幅值可调的三相正弦波实验电路,模拟正常及故障状态下的电压波形。     

大动态范围增益可控固态放大器系统的实现

针对雷达发射多波束的需求,研制了一套基于氮化镓高电子迁移率晶体管三代半导体器件的增益可控固态放大器系统。描述了系统中微波放大模块、幅相控制和相位补偿的实现方案,分析了功率放大器栅极电压与放大器增益和输出信号相位的关系。通过幅相控制电路实现发射通道输出信号幅度和相位快速转换,满足发射多波束的需求。经试验验证,研制的大动态范围增益可控固态放大器系统,提高了效率和工作带宽,解决了传统发射多波束系统中的问题。     

中性点不接地系统单相接地故障分析与仿真

在小电流接地系统中,当出现单相接地故障的时候,因为它构不成短路回路,负荷电流比接地短路产生的电流大得多,而故障相的对地电压本身又小得多,所以故障相的对地电压以及非故障相的相电压均发生变化,前者降低、后者升高,但线电压却依然是对称的,所以用户依然能够不受影响地使用电能,在该系统下可维持运行1到2小时。因为单相接地是一种比较容易见到的故障类型,所以在该文中,采用Matlab仿真软件,模拟小电流接地系统(这里仅对中性点不接地系统进行分析)单相接地故障,建立仿真模型,通过设置电源、线路等参数以及仿真参数,模拟出了仿真结果及系统各个主要参数的波形图,最后根据仿真结果,得出重要结论。     

参数自动配置的量子密钥分配系统设计与实现

文章基于法拉第——迈克尔逊干涉仪的相位编码量子密钥分配(QKD)系统,设计并实现了该系统的参数自动化配置。该系统中的三个参数:同步光输出光强、单光子探测器的门触发时间窗口和相位调制器的调相电压需要根据公共信道的衰减和距离进行配置。通过同步光光强扫描、单光子探测器延时扫描和相位调制器调相电压扫描来实现上述三个参数的自动配置。整个自动化配置过程可以在 1min 内完成,实现了 QKD 系统的快速配置。     

自适应锁相环的设计与仿真

在三相电压不平衡时,负序分量会在Park变换后产生一个2倍基频的波动,进而影响对基频分量相位的提取。针对一般的锁相环在电网三相不平衡时无法准确锁定电网的相位,本文提出一种基于陷波器的自适应锁相环,利用自适应陷波器(ANF)能够输出两个相互正交分量的特点,生成两个能抵消dq坐标系的负序分量,这样就实现了基波的正序负序分离。在Matlab/Simulink中建立仿真模型进行验证,结果表明了文中所提的方法在电网不平衡时可以准确地锁定电网的相位。     

An adaptive dead-time compensation strategy for voltage source inverter fed motor drives

This paper presents an adaptive dead-time compensation strategy to obtain fundamental phase voltage for inverter fed vector controlled permanent magnet synchronous motor drives. The amplitude of phase dead-time compensation voltage (DTCV) to compensate disturbance voltage due to undesirable characteristics of inverter, such as dead-time, turn-on/off time of switching devices, and on-voltages of switching devices and diodes is adaptively determined according to a dead-time compensation time (DTCT). DTCT is identified on-line with using a /spl delta/-axis disturbance voltage in the current reference frame that is synchronized with current vector. The /spl delta/-axis disturbance voltage is estimated by a disturbance observer. The accuracy of identified DTCT is experimentally confirmed by calculating the mean absolute percentage error (MAPE) between a calculated active power and a measured one. MAPE for adaptive DTCT is almost within 5% at any operating point.     

三相电源过零信号检测及相序自适应的研究与实现

为了实现对电机的同步控制,提出了一种获取三相交流电的电压过零信号和电源相序自适应方法.该方法以P87C591单片机为核心,利用6N137光耦和P87C591单片机的捕获功能实现对电压过零点的检测;由软件实现时电源相序的判断和相序的自适应.这里对其硬件和软件给予了详细分析.实际应用表明,该方案经济、稳定、可靠.     

一种自适应时间常数匹配Gm-C电感电流采样方法

提出了一种自适应时间常数匹配G_m-C电感电流采样方法。该方法通过比较Buck变换器SW点电压的过零时间与G_m-C滤波采样电压的过零时间,判断G_m-C时间常数是否与DCR时间常数匹配。使用鉴频鉴相器检测二者过零时间差,并控制双向计数器,实现对电容阵列等效容值的调制,最终实现自适应时间常数匹配G_m-C电感电流采样。与前序工作相比,该校准过程平滑,并且可以在DC-DC变换器正常工作情况下进行在线调制,能有效适应DC-DC变换器工作中温度、电压、电流等外部条件的变化。     

带自适应体偏置的宽带LC VCO自动幅度控制策略

为了优化宽带LC型压控振荡器（LC VCOs）相位噪声性能,提出一种自动幅度控制策略。该策略结合了自适应体偏置和数字校准。当VCO开始工作时,自适应体偏置技术使VCO在不同的工艺角、电压和温度（PVT）情况下快速起振。当谐振频率变化时,在自适应体偏置和数字校准的作用下,VCO的谐振幅度被控制在最优值附近,达到优化相位噪声的目的。在TSMC 0.18μm CMOS工艺中,覆盖频率范围为1.6～3.2GHz的宽带LC VCO用来验证该幅度控制策略的可行性。基于SpectreRF的仿真结果表明LC VCO的幅度变化率降低90%,且在3.2GHz谐振频率,10kHz频率偏移处的相位噪声改善8.2dB。     

基于功率检测自适应的前馈功放设计

分析了常用双环自适应前馈电路在屏蔽和宽带频率兼顾等地方的缺陷,设计了一个功率检测自适应电路。功率检测自适应应用于前馈系统第一极环路,通过MCU监控电压检测值,自动调节第一环路的移相、调幅矢量调节器,改变相位、幅度参数,以达到环路抵消最好,保证在功率与频率不断变化的情况下,误差信号提取时刻都保持最纯净。仿真结果显示,在输出125W的GSM前馈系统中,可使其IMD3小于-65dBc。     

A low power current-reuse LC-VCO with an adaptive body-biasing technique

This work presents a low-power low-phase noise current-reuse LC voltage controlled oscillator (VCO) with an adaptive body-biasing technique that enhances the reliability of the proposed circuit under process, voltage, and temperature (PVT) variations. Furthermore, the supply voltage and power consumption of the proposed VCO are reduced by the start-up oscillation condition that is provided by the adaptive body-biased circuit. This property is in fact very interesting from the power management perspective. The proposed VCO works at carrier frequency of 1.8 GHz and draws the power of only 306 µW from a 0.9 V supply. It achieves phase noise of −123.36 dBc/Hz at 1 MHz offset and provides a figure-of-merit (FoM) of −193.61 dBc/Hz. The post-layout simulation results of designed VCO in 0.18 µm standard CMOS technology confirm the effectiveness of the proposed circuit.     

Control of series active power filters compensating for source voltage unbalance and current harmonics

In this paper, a novel control scheme compensating for source voltage unbalance and current harmonics in series-type active power filter systems combined with shunt passive filters is proposed, which focuses on reducing the delay time effect required to generate the reference voltage. Using digital all-pass filters, the positive voltage sequence component out of the unbalanced source voltage is derived. The all-pass filter can give a desired phase shift and no magnitude reduction, unlike conventional low-or high-pass filters. Based on this positive-sequence component, the source phase angle and the reference voltage for compensation are derived. This method is easier to implement and to tune controller gains. In order to reduce the delay time effect in the voltage control loop, the reference voltage is predicted a sampling period ahead. The validity of the proposed control scheme has been verified by experimental results.     

Reliability analysis of MOS varactor in CMOS LC VCO

The paper investigates the reliability of MOS varactor tuned voltage-controlled oscillators (VCO). Due to the stress induced threshold voltage shift of the MOS varactor, the resonant tank degrades and the center frequency and phase noise of VCO deviate. The behavior is modeled and an adaptive body biasing scheme is proposed to make VCO resilient to reliability. In the mean time it does not degrade the VCO performance. An LC VCO at 24 GHz carrier frequency with adaptive body biasing is compared with VCO without such biasing design in PTM 65 nm technology. The ADS simulation results show that the biasing design helps improve the robustness of the VCO in resonant frequency. The design reduces the frequency sensitivity of VCO by 20% when subjected to threshold voltage degradation.     

Voltage Injection Method for Three-Phase Current Reconstruction in PWM Inverters Using a Single Sensor

This paper presents a voltage injection method for reconstructing phase currents from current signals measured on single current-shunt circuits with cost-effective and high-performance configurations in the pulsewidth modulation (PWM) inverters that are used for digital appliances. This method involves the injection of voltage signals at the carrier frequency for reconstructing the phase currents in PWM inverters using a single current sensor in the DC-link. It uses minimum signals to reduce the voltage and current harmonics caused by the injected signals. The vector of the injected voltage is at a minimum distance from the original reference to ensure the measurement time in the reconstruction of the phase currents. An injection sequence control method is also proposed to avoid an abrupt change in the injection signals. A PWM scheme for splitting phase voltages is proposed to reduce any audible noise, especially in low-speed operation. The proposed method reconstructs the phase currents with signals from a single current sensor and minimizes the amplitude of the injected signals to reduce the harmonics at audible noise frequencies in the injection signals. Experimental results showed the effectiveness of the proposed method.