从UPS电路拓扑看在线式UPS的性能优势

本文介绍分析了后备式、在线互动式和在线双变换式等各类UPS电路拓扑与性能,指出在线或UPS性能优势所在。     

Practical Control Implementation of a Three- to Single-Phase Online UPS

A high-performance three- to single-phase online uninterruptible power supply (UPS) is proposed. The proposed UPS is composed of a rectifier, a battery charger/discharger, and an inverter. The rectifier has the capability of power-factor correction and regulates a dc-link voltage. When the rectifier becomes unavailable or when the current required by the load exceeds the output rating of the rectifier, the charger/discharger supplies the power demanded by the load to a dc-link capacitor. The inverter provides a regulated sinusoidal output voltage and limits an output current under an impulsive load. New control algorithms of the rectifier, the charger/discharger, and the inverter are proposed. The proposed algorithms of the rectifier and the charger/discharger improve dynamic performance at step load change. To improve the transient response of the output voltage at outage of an input source, a mode change method of the charger/discharger is also proposed. Additionally, the proposed current-limit algorithm of the inverter can be implemented without additional hardware, and it increases the reliability of the UPS.      

基于DSP控制的在线式UPS装置研究

介绍了一种基于Ti（Texas Instruments）公司的TMS320F240数字信号处理器的在线式UPS，分析了系统设计中的一些关键技术问题。设计了一台容量为6kW的在线式UPS试验装置，并进行了验证，实践证明所研制的装置完全达到技术要求。     

Design of Transformerless Modulator-Demodulator

A transformerless modulator-demodulator that operates over a wide range of frequencies is described. The circuit is designed to exhibit symmetrical full wave rectification, to eliminate offset voltages at the output, and to lack the necessity of being fed from a voltage source. The equations to achieve these features are developed. To satisfy all these equations certain relations between various components must be observed. The solutions of these, obtained by a computer, are given for typical gains.     

Transformerless Single-Phase Multilevel-Based Photovoltaic Inverter

The elimination of the output transformer from grid- connected photovoltaic (PV) systems not only reduces the cost, size, and weight of the conversion stage but also increases the system overall efficiency. However, if the transformer is removed, the galvanic isolation between the PV generator and the grid is lost. This may cause safety hazards in the event of ground faults. In addition, the circulation of leakage currents (common-mode currents) through the stray capacitance between the PV array and the ground would be enabled. Furthermore, when no transformer is used, the inverter could inject direct current (dc) to the grid, causing the saturation of the transformers along the distribution network. While safety requirements in transformerless systems can be met by means of external elements, leakage currents and the injection of dc into the grid must be guaranteed topologically or by the inverter's control system. This paper proposes a new high-efficiency topology for transformerless systems, which does not generate common-mode currents and topologically guarantees that no dc is injected into the grid. The proposed topology has been verified in a 5-kW prototype with satisfactory results.     

Transformerless DC-to-DC converters with large conversion ratios

A novel switching DC-to-DC converter is introduced in which large voltage step-down ratios can be achieved without a very small duty ratio and without a transformer. The circuit is an extension of the Cuk converter to incorporate a multistage capacitor divider. A particularly suitable application would be a 50 V to 5 V converter in which DC isolation is not required. The absence of a transformer and a larger duty ratio permits operation at a high switching frequency and makes the circuit amenable to partial integration and hybrid construction techniques. An experimental 50 W three-stage voltage divider Cuk converter converts 50 V to 5 V at 500 kHz, with an efficiency higher than that for a basic Cuk converter operated at the same conditions. A corresponding voltage-multiplier Cuk converter is described, as well as dual buck-boost-derived step-down and step-up converters     

单相高效无变压器式光伏逆变器的设计理念

效率已经成为衡量光伏逆变器最重要的一个指标。本文针对单相小功率光伏逆变器应用,详细介绍了改善光伏逆变器效率的方法,并结合Vincotech公司最新推出的功率模块(FZ06BIA045FH-P897E)给出了具体应用和仿真结果。     

产生双极性输出的无变压器DC／DC变换器

要从单个正极性输入产生双极性(正和负)输出的常见方法是采用变压器.虽然这种设计比较简单,但变压器本身会带来体积问题.把一个变压器装入一台要求减小电路占用面积和高度的设备中,这是具有挑战性的.图1所示电路可以从由3V～10V输入产生±5V输出,适用于没有地方安装变压器的设备.该电路所用的一种结构,能在DC/DC变换器处于关机模式时切断两个输出,这样就使处于关机(待机)模式时的静态电流很小.     

浅谈UPS

1UPS概述 随着计算机技术的高速发展,计算机控制技术广泛应用于各个行业中.     

UPS系统技术和Delta变换UPS系统

阐述国内外UPS系统技术现状和发展趋势,讨论传统的双变换在线UPS系统存在的问题及解决办法,介绍单变换UPS系统,最后着重介绍Delta变换UPS系统。     

Transformerless series sag compensation with a cascaded multilevel inverter

The use of a cascaded multilevel inverter for transformerless sag/dip compensation is investigated. This topology is investigated as a cost-effective means for series sag compensation by eliminating the large injection transformer and output filter components that are used in conventional series injection devices. This prototype inverter is designed for sag compensation of a 250-kVA load. In this design, cost effectiveness plays a major role in the selection of the energy storage and the switching components. Control schemes are discussed for series sag compensation with this multilevel inverter. New control methods for sag compensation and injection are also introduced. A prototype is developed and the control schemes of this sag compensator are successfully verified in the practical results and show successful compensation for sags for different types of loads. The performance of this compensator makes it promising for future power rating upgrade and industrialization.     

UPS and downs

The latest annual report on distribution and transmission system performance from the Office of Electricity Regulation presents a reasonably cheerful picture to the electricity consumer in general. But it also throws into sharper focus the risks that businesses run if they fail to provide uninterruptible power support for their computer installations. The author describes how, nevertheless, many companies still run that risk. Many computer systems are more vulnerable to power-related problems now than ever before. If ever there was a time for companies to look at their power back-up strategy, it is now     

Transformerless r.p. immittance synthesis from real-part specification

A method is proposed for synthetising transformerless r.p. immittance for the case in which only their real part on the imaginary axis is of interest. The method presents the advantage of requiring a very low number of components and very simple computations.     

高性能HBLED的测试

高亮度LED (HBLED)相比传统的LED具有高得多的性能,但是同时具有更高的成本。这两个因素决定了HBLED在研发和生产阶段的测试方式。测试需求高亮度发光二极管(HBLED)凭借其高效率、长寿命和色彩丰富等特性正快速发展。这些特性使得     

无逆变高效率UPS电源

液晶显示器已取代传统CRT显示器,个人电脑的主机和显示器都由直流供电;利用高效率的DC／DC转换器设计无逆变电路的LIPS电源,可节省LIPS电源的能量损耗和成本,并进一步提高电路的可靠性。     

UPS“守护神“蓄电池在线监测系统

UPS在通讯及其它领域获得了广泛应用,但人们却忽视了UPS自身的有效性检测.本文分析了UPS蓄电池在线监测的原理,指出了蓄电池在线监测系统的解决方案.     

UPS蓄电池的选择

蓄电池是UPS系统中的一个重要组成部分。因此，UPS电池的选择不仅关系到经济成本问题、还直接影响UPS电源的不间断供电。根据UPS电池的特点，从电池类型、容量计算、配置方式、寿命及品牌等五个方面分析了如何选择满足负载需要的既经济又可靠的UPS电池，对通信系统长效型UPS电池的选择具有一定的借鉴意义。     

无变压器型混合有源滤波器及其控制策略研究

在对一种无变压器型混合有源滤波器的电路拓扑和参数设计方法进行分析研究的基础上,提出一种采用电网谐波电流作反馈控制与负载谐波电流作前馈控制的复合控制策略,并用SIMULINK建立仿真模型进行仿真分析。通过与仅采用电网谐波电流作反馈控制时的仿真结果进行比较,可以看出使用这种复合控制方法,能更有效地抵消电网中的谐波电流,降低总的谐波畸变率。     

Improved single-phase line-interactive UPS

An improved single-phase line-interactive uninterruptible power supply (UPS) is proposed for low-power applications with low cost. The proposed UPS is comprised of two push-pull converters based on a low-voltage battery for reduced cost: one in series with the input and the other in parallel with the load. In the presence of input power, the UPS acts as an output voltage regulator and at the same time as an active filter while charging the battery. In case of loss of input power, the UPS supplies a regulated sinusoidal voltage to the load, drawing power from the battery. The series converter compensates only a small percentage of the input voltage carrying the input current and, therefore, a reduced rating is made. The parallel converter always supplies a nominal voltage and makes a seamless transition to backup mode. In the voltage determination of the parallel converter, the nominal voltage is derived using the feedback linearization concept and then a perturbed voltage is determined for the reactive power control or output voltage regulation. Experimental results obtained from a 1-kVA prototype are discussed     

无逆变高效率UPS电源

液晶显示器已取代传统CRT显示器,个人电脑的主机和显示器都由直流供电;在新型UPS中可将交流220V整流滤波成300V直流电,或将电池电压经DC/DC升压至300V,后将300V直流电经DC／DC转换成计算机所需的各组直流电,无需再逆变回交流220V;这种利用高效率的DC／DC转换器设计无逆变电路的UPS电源,可节省UPS电源的能量损耗和成本,并进一步提高电路的可靠性。