Input Current Harmonics in a Regenerative Multicell Inverter With Single-Phase PWM Rectifiers

Harmonics are a very important issue in the design and operation of medium-voltage inverter drives, due to restrictions imposed by regulations. This paper studies the harmonics generated by a three-phase multicell cascade inverter, with single-phase pulsewidth modulation rectifiers at the input side of each cell; thus, the entire topology is able to regenerate power to the net. This paper identifies accurately the harmonic generation process in the dc-link voltage, the input current of each cell, and, therefore, at the input side of the inverter. Moreover, this paper proposes a method to reduce and, in some cases, eliminate the input current harmonics, reaching a very high input power factor for any operation condition. Simulation and experimental results are provided to validate the theoretical analysis.      

A Control Circuit With Load-Current Injection for Single-Phase Power-Factor-Correction Rectifiers

A load-current-injection control technique for boost-derived power-factor-correction (PFC) rectifiers with average current-mode control is proposed in this paper. By adding a load-current loop to the conventional inductor current loop, the output voltage response to load steps is speeded up, almost eliminating the typical voltage overshoots of this kind of converters. Although the techniques based on the load-current injection are traditionally called "load feedforward," this paper shows that an additional feedback loop, which modifies the linear small-signal model of the converter, is also introduced. In order to validate the concept, a converter prototype working from a universal input line has been designed and tested, showing that a very fast dynamic response of PFC rectifiers may be achieved in a cost-effective way     

三相电压型PWM整流器控制技术的发展

本文对三相电压型PWM整流器主要控制技术、原理、特点进行了系统的分析和综述。包括滞环PWM电流控制、固定开关频率的电流控制、预测电流控制、矢量控制、直接功率控制以及单周期控制;此外,文中评述了国内对电压型PWM整流器控制技术研究的主要贡献。在此基础上,对PWM整流器控制技术发展趋势进行了展望。     

A Simple Analog Controller for Single-Phase Half-Bridge Rectifier

A simple analog controller is proposed for the single-phase half-bridge pulsewidth modulation rectifier to maintain near unity power factor at the input and balance the voltages across each half of the dc bus. The controller works in the principle of constant-frequency current programmed control. The required gating pulses are generated by comparing the input current with a linear and bipolar carrier without sensing the input voltage. Two voltage controllers and a single reset-integrator are used to generate the carrier. All the necessary control operations are performed without using any phase locked loop, multiplier, and/or divider circuits. Resistor based sensors are used to measure the voltages across two halves of the dc bus and the input current. The controller can be fabricated as a single integrated circuit. The averaged small signal models and all the necessary design equations are provided. The condition of stability against subharmonic oscillation is analyzed. Calculation of switching and conduction losses is presented. The control concept is validated through simulation and also experimentally on an 800-W half-bridge rectifier. Experimental results are presented for ac-dc application, and also for ac-dc-ac application with both linear and nonlinear loads at two different output fundamental frequencies (50 and 60Hz)     

效率为98%的单相和三相单级交流-直流变换器拓扑结构

目前在电力电子技术研究领域,具有隔离和功率因数校正功能的单级AC-DC变换器,均是依赖于全桥整流的新型变换器。当前的单相AC-DC变换器是基于传统的脉宽调制(PWM)变换方法实现的,它至少包括三个不同的功率信号处理级:全桥整流器、BOOST PFC变换器和串联隔离式全桥DC-DC变换器,共用到14个开关器件和3个磁性元件,这些都对变换器的效率、尺寸和成本限制产生影响。本文所介绍的混合变换方法实现了一种新型单级AC-DC变换器拓扑结构,是一种只包括三个开关器件和一个磁性元件的非桥型PFC变换器。这种变换器具有98%左右的效率、0.999的功率因数和总共仅1.7%的谐波畸变。三相整流器包含了三个这样的单相整流器,它利用了特斯拉三相转换系统的优点,可以进行三相系统的输入功率到直流输出功率的瞬态转换,具有高频光隔离,0.999的功率因数,低谐波畸变(1.7%),较小的尺寸和成本等特点,而且效率达到了98%。     

单相可逆PWM整流器能量双向传输的研究

高功率因数电能交换和负载电能回馈电网的实现是电力节能的关键问题.在对电压型单相PWM(Pulse-width Modulation)整流器的拓扑结构以及其工作原理的分析基础上,提出了相应的控制方法并分别对主电路参数和PI调节器参数进行了选择和设计.基于Matlab计算机仿真软件对整个单相PWM整流器控制系统进行了建模和仿真,结果表明PWM整流器控制系统能很好实现高功率因数电能变换和电能的双向流动.     

基于DFT变换的单相PWM整流IGBT断路故障检测

单相整流变换和三相整流变换被广泛的运用在电力机车牵引变流器,风力发电,光伏发电等各种工业设备中,并且单相整流变换相对于三相整流变换更加容易发生故障。本文主要是介绍了一种通过在频域中对直流侧电流进行分析,从而判断IGBT断路故障的故障诊断方法。该方法并不需要增加额外的传感器,也不需要对电路模型进行详细的分析,而是通过在频域中使用故障诊断算法就可以确定发生的故障类型。通过实验验证表明该发生具有快速的诊断时间,简单的算法结构,高可靠型等特点。     

Reducing the Response of Single-Phase Transmission Lines to Electrical Noise

The reception of unwanted noise can be drastically reduced in a single-phase transmission line by employing 2N, N = 1,2,. ., conductors with alternate wires connected in parallel. The cross section of the line forms a regular polygon. The advantage of the four-wire line over the two-wire line for discrimination against noise is exhibited.     

A Direct PWM Technique for a Single-Phase Full-Bridge Inverter Through Controlled Capacitor Charging

The controlled-capacitor-charging (CCC) technique is utilized in this paper to synthesize a sinusoidal voltage at the output from the unregulated dc at the input. The method is based on the controlled charging/discharging of a capacitor to realize the desired voltage waveform. A capacitor that is connected across the load is charged/discharged through an inductor by applying high-frequency pulses. The applied pulses could be of either positive or negative polarity, depending on the error signal in the controller. The controller senses the output voltage and current and operates to maintain zero-current switching at every turn-on while keeping the output voltage close to the reference waveform by a tracking-control algorithm, enforcing limits in maximum switching frequency and voltage ripples. This paper presents a direct method of implementing the pulsewidth modulation for the single-phase full-bridge inverter, using the CCC technique. A simple procedure to design such an inverter is also discussed. The proposed controller is simulated in a personal computer simulation program with integrated circuit emphasis. Supporting results from an experimental prototype confirm the usefulness of the proposed controller. The inverter may be used in uninterruptible power supply and many other applications.      

基于旋转坐标变换的单相电压型PWM整流器系统仿真

为了抑制网侧电流静差,改善调制波输出质量,文章讨论了一种基于旋转坐标变换的单相电压型PWM整流器d—q轴电流矢量控制策略。采用单极性SPWM调制方式,并考虑单相系统的特殊性,通过构建正交虚拟电流完成网侧电流的旋转坐标变换,以实现对网侧电流的矢量控制。在Matlab2007a／Simulink环境下建立了控制系统的仿真模型,详细讨论了各主要模块的搭建方法,并在此基础上给出了仿真结果。仿真结果表明,基于旋转坐标变换的单相PWM整流器d—q轴电流矢量控制策略的可行性,以及其对交流量误差调节的有效性。     

提高可编程增益放大器准确度的一种简单方法

数字的可编程性已经成为复杂的混合信号系统里的一个非常必要的特征。可编程增益放大器已广泛应用于各种各祥的应用中,它主要用于优化整个系统的动态范围。由于它是用数字信号控制并且有很大的增益范围,所以需要用开关来选择使动态范围最大的那个增益。这篇论文讲述了一个简单的方法来提高增益的准确度。这个方法采用开关的并联合电阻的组合作为一个单元,它能使可编程增益放大器的增益和开关的可变电阻无关。设计了一个可编程增益放大器验证了这个方法的可行性。它用0．18um CMOS技术生产,增益范围是-28～35dB,步长是1dB。有6位数字信号控制,仿真结果表明了精度可达到0.05dB。     

Presence Network Agent: A Simple Way to Improve the Presence Service

The article examines a possible way of improving the performance of the presence service within IMS networks without modifying the presence and group management enabler. This can be achieved by means of a presence network agent (PNA). The PNA has been defined by 3GPP in [1]; it is a new logic entity within the IMS core network that is able to publish the presence information on behalf of the presentity user agent. The PNA improves performance because it reduces the presence signaling load within the radio access network without downgrading the freshness and richness of the presence information. The article?s goal is to provide the reader with useful information about the PNA and our experience with PNA implementation and deployment. We first describe the PNA concept as defined by 3GPP, highlighting the open issues still present in the standardization and the possible optimizations, subsequently we present an actual implementation of a PNA handling busy/idle states for IMS calls.     

Simple topologies of PWM AC-AC converters

This letter proposes a new family of simple topologies of PWM AC-AC converters with minimal switches. With extension from the basic DC-DC converters, a series of AC-AC converters such as buck, boost, buck-boost, Cuk, and isolated converters are obtained. By PWM duty ratio control, they become a "solid-state transformer" with a continuously variable turns ratio. All the proposed AC-AC converters in this paper employ only two switches. Compared to the existing circuits that use six switches or more, they can reduce cost and improve reliability. The operating principle and control method of the proposed topologies are presented. Analysis and simulation results are given using the Cuk AC-AC converter as an example. The analysis can be easily extended to other converters of the proposed family.     

用于D类音频功放的动态迟滞PWM比较器

系统介绍了基于PWM(Pulse Width Modulation)调制的D类音频功率放大器的原理及特点.针对传统比较器迟滞固定的不足,通过引入两路电流反馈,设计了一种新颖的动态迟滞PWM比较器.同等分辨率下,其抗噪声能力远好于传统的比较器.电路设计基于TSMC0.6Vxn BCD工艺.Spectre仿真结果表明,在载波以及输出的不同状态下,比较器的迟滞在20mV与80mV之间切换,其增益高达79dB,单位增益带宽大干10MHz.     

一种提高栅氧化物介电常数的方法

从90 nm技术节点开始,等离子氮化SiON栅氧化层被广泛用作先进的CMOS器件制造。作为传统SiO2栅氧化层的替代材料,SiON栅氧化层因其具有较高的介电常数而能有效地抑制硼等栅极掺杂原子在栅氧化层中的扩散。氮化后热退火处理(Post Nitridation Anneal,PNA)是制备等离子氮化SiON栅氧化层的一个重要步骤,主要用于修复晶格损伤并形成稳定Si-N键,同时在氧化氛围下通过界面的二次氧化反应来修复SiO2/Si界面的损伤。本文通过对传统栅氧制备工艺中PNA单一高温退火工艺的温度、气体氛围进行优化,提供了一种通过提高栅氧化物的氮含量来提其高介电常数的方法。实验数据表明,与传统的制备方法相比,采用本方法所制备的SiON栅氧化层中氮含量可以提高30%以上,栅氧界面态总电荷可减少一个数量级,PMOS器件的NBTI寿命t0.1%和t50%可分别提高15.3%和32.4%。     

一种提高软件可靠性预计质量的方法

利用软件可靠性模型可以预计软件能够达到的可靠性水平,但预计质量有时会很差,即预计结果和实际情况之间存在较大偏离.将几组在软件测试过程中收集到的失效数据运用于两种软件可靠性预计模型,利用U图分析偏离情况,在此基础上提出一种减少偏离的方法,经过对比发现该方法能明显降低偏离.     

一种高精度测频方法

论述一种提高测频精度的方法,对测频原理进行了分析,并对其进行了仿真。模拟结果显示,其实现方法简单,对数字接收机提高测频精度有一定的理论和实际意义。     

增加光节点的简便方法

早期建设的有线电视光纤网，普遍存在光节点分布太稀和光纤芯数裕量太少的问题，为此，介绍两种使用超低光功率接收机增加光节点的方式和光链路设计，以及选用超低光功率接收机要考虑的因素，并将新增节点光链路延伸不同长度的分光比计算结果列成表格，以供工程中直接查用。     

A Single-Phase Active Filter Using an H-Bridge PWM Converter With a Sampling Frequency Quadruple of the Switching Frequency

This paper presents a digital current regulator for H-bridge pulsewidth modulation (PWM) converters, whose sampling frequency equals quadruple of the switching frequency. The current regulator detects the ac current and manipulates the voltage reference not only at the upper and lower peaks of the PWM triangle carrier but also at its zero crossings. This paper theoretically discusses the switching sequence of the H-bridge PWM converter, and reveals the amount of the voltage error and the condition where the voltage error occurs. A modified deadbeat current regulator is proposed to suppress the current oscillation induced by the voltage error, based on the theoretical analysis. Experimental results are shown to verify the control performance of the proposed current regulator. Moreover, a proposed current regulator is applied to a single-phase active power filter to demonstrate the effectiveness in harmonic compensation.     

数字锁相环提高锁相稳定性的方法

文中针对光伏并网发电系统中数字锁相环易受到过零检测电路影响,其稳定度差的问题,采用了相应的硬件和软件方法解决锁相环稳定性问题。硬件上通过提前过零检测来补偿加重滤波器带来的相位滞后;软件上加入判断过零点真伪的功能,以及先检测过零点再切换后级逆变桥的方法,有效地避免了错误过零点造成的锁相失败问题,取得了很好的效果。