A Unity Power Factor Correction Preregulator With Fast Dynamic Response Based on a Low-Cost Microcontroller

Low cost passive power factor correction (PFC) and single-stage PFC converters cannot draw a sinusoidal input current and are only suitable solutions to supply low power levels. PFC preregulators based on the use of a multiplier solve such drawbacks, but a second stage dc-dc converter is needed to obtain fast output voltage dynamics. The output voltage response of PFC preregulators can be improved by increasing the corner frequency of the output voltage feedback loop. The main drawback to obtaining a faster converter output response is the distortion of the input current. This paper describes a simple control strategy to obtain a sinusoidal input current. Based on the static analysis of output voltage ripple, a modified sinusoidal reference is created using a low cost microcontroller in order to obtain an input sinusoidal current. This reference replaces the traditional rectified sinusoidal input voltage reference in PFC preregulators with multiplier control. Using this circuitry, PFC preregulator topologies with galvanic isolation are suitable solutions to design a power supply with fast output voltage response (10 or 8.33 ms) and low line current distortion. Finally, theoretical and simulated results are validated using a 500 W prototype.     

Analysis and Design of a Modular Three-Phase AC-to-DC Converter Using CUK Rectifier Module With Nearly Unity Power Factor and Fast Dynamic Response

In this paper, the analysis and design of a modular three-phase ac-to-dc converter using single-phase isolated CUK rectifier modules is discussed based on power balance control technique. This paper analyzes the operation of a modular converter as continuous-conduction-mode power factor correction (CCM-PFC). Design equations, as well as an average small-signal model of the proposed system to aid the control loop design are derived. It is used to obtain the inductor current compensator, thus the output impedance and audio susceptibility become zero, and therefore, the output voltage of the converter presented in this paper is independent of the variations of the dc load current and the utility voltage. The control strategy consists of a single output voltage loop and three-inductor current calculator. The main objective of the proposed system is to reduce the number of stages and improve dynamic response of dc bus voltage for distributed power system. The proposed scheme offers simple control strategy, flexibility in three-phase delta or star-connected, simpler design, fast transient response, good inductor current sharing, and power factor closed to unity. Both simulation and experimental results are presented. They are in agreement with the theoretical analysis and experimental work.      

Model-Based Real-Time Dynamic Power Factor Measurement in AC Resistance Spot Welding With an Embedded ANN

Today, real-time measurement of dynamic power factor in resistance spot welding (RSW) is of increasing importance. On the basis of the welding transformer circuit model, a new method is proposed to measure the peak angle of the welding current and then calculate the dynamic power factor in each half-wave. The tailored sensing and computing system ensures that the measuring method possesses a real-time computational capacity with satisfying accuracy. Since the power factor cannot be represented via an explicit function with respect to measurable parameters, the traditional method(s) has to approximate the power factor angle with a constant phase lag angle and fails to detect its dynamic characteristics. An offline-trained embedded artificial neural network (ANN) successfully realizes the real-time implicit function calculation or estimation. A digital-signal-processor-based RSW monitoring system is developed to perform ANN computation. Experimental results indicate that the proposed method is applicable for measuring the dynamic power factor in single-phase half-wave controlled rectifier circuits     

Two-Stage Uninterruptible Power Supply With High Power Factor

An uninterruptible power supply (UPS) with high power factor and two conversion stages is suggested. The double-conversion configuration has three stages, but normally, only two stages are operating at the same time. The first stage of the proposed scheme integrates the power-factor-correction stage and the battery charger of the double-conversion configuration, obtaining a two-stage UPS. The second stage is based on the theory of inverter with boosting capabilities. The battery set has not only been completely isolated, but it has also been charged with a small change at the controller set point; these particular characteristics facilitate the system maintenance and simplify its operation. Additionally, the battery-set voltage is low, reducing the weight and size. The converter operation, analysis, design, and experimental results are shown. The proposed UPS approach is practical in low-power applications ($leq 500$ W).      

A Current-Mode DC-DC Buck Converter with High Stability and Fast Dynamic Response

提出了一种高稳定性的电流型DC-DC转换器.首先应用一种新型的电流型转换器的模型推导了控制环路的增益表达式,在分析其环路增益的基础上,提出了一种新颖的控制环路频率补偿的方法,从而使转换器的稳定性不受负载电流和电源电压变化的影响.其次应用这种新的频率补偿方法,使用0.5μm-CMOS工艺设计了一种电流模式的降压型转换器.仿真结果表明,该稳压器具有高度的稳定特性,其稳定性与负载和电源电压无关.并且由于这种新的频率补偿为环路提供了极高的带宽,所以该转换器具有优异的动态响应.其提供的全负载瞬态响应的建立时间小于5μs,过冲电压小于30mV.     

具有快速动态响应的高稳定性电流型降压DC-DC转换器

提出了一种高稳定性的电流型DC-DC转换器.首先应用一种新型的电流型转换器的模型推导了控制环路的增益表达式,在分析其环路增益的基础上,提出了一种新颖的控制环路频率补偿的方法,从而使转换器的稳定性不受负载电流和电源电压变化的影响.其次应用这种新的频率补偿方法,使用0.5μm-CMOS工艺设计了一种电流模式的降压型转换器.仿真结果表明,该稳压器具有高度的稳定特性,其稳定性与负载和电源电压无关.并且由于这种新的频率补偿为环路提供了极高的带宽,所以该转换器具有优异的动态响应.其提供的全负载瞬态响应的建立时间小于5μs,过冲电压小于30mV.     

大功率UPS的配置

企业在购买大功率UPS设备的过程中,常常会遇到在工频机和高频机之间进行选择的困惑。从设备厂商方面讲,提供工频机的说工频机稳定性和可靠性高,提供高频机的会说高频机节省空间，成本相对较低，等等。其实，工频机和高频机到底孰优孰劣，很难一概而论，可以说各有利弊。企业应当在全面认识这两种机型的基础上，根据自身的应用需求，     

Novel Current-Mode AC/AC Converters With High-Frequency AC Link

A novel circuit-topology family of the current-mode AC/AC converter with high-frequency AC link, based on a Flyback converter, is proposed. These circuit topologies, which can transfer one unregulated sinusoidal voltage with high total harmonic distortion (THD) into another regulated constant-frequency sinusoidal voltage with low THD, are composed of input cycloconverter, high-frequency storage transformer, and output cycloconverter. The circuit-topology family includes single four-quadrant power switch mode, push-pull mode, half-bridge mode, and full-bridge mode circuits. The single four-quadrant power switch mode and push-pull mode converters are suitable for low input voltage fields, but the half-bridge mode and full-bridge mode converters are suitable for high input voltage fields. The operational mode, steady principle, and transient voltage feedback control strategy of the kind of converter are investigated. The output characteristic curve, its relation to internal resistance, and the design criteria for the key circuit parameters are given. The theoretical analysis and the test result of the 500 VA 220 V 15% 50 HzAC/220 V 50 HzAC prototype have shown that the converters have advantages such as high-frequency galvanic isolation, simple topology, two-stage power conversion [low frequency alternating current (LFAC)/high frequency alternating current (HFAC)/LFAC], bidirectional power flow, high efficiency, high power density, low THD of the output voltage, strong adaptability to various loads, higher line power factor, low audio noise, etc.     

一种高增益快速响应且无片外电容型LDO设计

设计了一款无片外电容低压差线性稳压器(LDO),其瞬态响应速度极快,且增益高、带宽宽,输入电压范围为2.8V~5.0V,输出电压2.4V。使用HSPICE仿真验证了直流、交流、瞬态、温度等特性。在Typical工艺角情况下,负载电流以100mA/1μs突变时,输出电压突变量最大为89mV。重载与轻载模式下电压差也仅为16.8mV,在两种极端工艺角条件下,输出电压突变量最大108mV。此LDO无片外电容,整个片内补偿电容仅为4pF,3dB带宽为4068Hz,0dB带宽高达52MHz。     

一种快速动态分布式光链路建立方法

提出一种改进的波长分配算法,用于波长路由光网络中快速动态分布式光链路的建立。该算法采用提前释放和超时释放两种波长和链路释放机制,减少了网络拥塞,更适合波长路由网络的实际运行规则。通过在美国自然科学基金网(NSF)上的仿真计算,与以前的研究结果相比,该算法可以减少网络的阻塞率8％,同时缩短了光链路建立的时间。     

A Burst-Mode 3R Receiver for 10-Gbit/s PON Systems With High Sensitivity, Wide Dynamic Range, and Fast Response

The burst-mode 3R receiver using monolithic ICs for 10-Gbit/s-class optical access networks is reported. In a point-to-multipoint access system like a passive optical network (PON), the receiver at the optical line terminal (OLT) must be able to handle burst-mode optical packets with significantly different powers and phases. An OLT receiver with high sensitivity with instantaneous response to burst inputs is desired for widening the accommodation area and for high efficiency in PON uplinks. Currently, the diffusion of high-speed Internet connection services represented by fiber to the home services at 1.25 Gbit/s is remarkable and the standardization of the next-generation system operating at 10 Gbit/s has started in IEEE. We first discuss the issues in the implementation of 10-Gbit/s-class PON systems, focusing on securing the accommodation area and the quality of the service comparable with those of the deployed system. Against that background, we propose target specifications for sensitivity, a dynamic range and response speed of the 10-Gbit/s-class burst-mode receiver so as to secure the power budget and the upstream efficiency comparable with those of the already-installed systems. Our burst-mode 3R receiver was designed to meet the above requirements and developed using monolithic ICs of transimpedance amplifier, limiting amplifier, and clock and data recovery circuit fabricated by using SiGe BiCMOS technologies along with a p-i-n photodiode. High sensitivity of , a wide dynamic range of over 16.5 dB, and quick response time of 75 ns were confirmed for burst inputs with extremely different powers.     

一种新型高压大功率变频器

针对当前高压大功率变频器在预充电技术上存在的不足,对其进行了改进方案的设计,提出了一种新型高压大功率变频器的设计构想。该新型变频器具有更优的预充电功能,无需高压开关,调试方便,操作性好,有着更好的系统可靠性和安全性,成本低廉,便于广泛应用。     

高功率因数电源设计

功率因数是开关电源设计的关键指标,提高功率因数是开关电源发展中一直重视的技术问题.这里设计的高功率因数开关电源应用PFC控制方式,引进TI公司新推出的UCC28019芯片,明显提高了功率因数.该电源由AC/DC变换电路、DC/IX;变换电路、PFC控制电路、功率因数检测电路、数字设定及测量显示电路、保护电路等6部分组成.其中,AC/DC变换电路采用桥式不控整流方式,DC/DC变换电路采用Boost拓扑结构,可实现30～36 V可调输出,并利用MSP430F247单片机实现数字设定、测量显示及功率因素检测等功能.该电源的主要优点是:功能直观、稳定性好、功率因数大幅度提高.     

一种新型高功率因数直流电源

文章提出了一种新型的高功率因数直流电源,并对电路的主要工作原理进行了分析,介绍了电路的两种工作模态,并且作了详细的比较;通过理论演算和对电路仿真,证实了该电路具有功率因数高的特点。与目前常用的boost功率因数校正电路比较,该电路改善了开关管的电压应力,使开关管不易损坏,同时还具有结构简单,效率高,性能稳定等优点。     

Novel Ultra-Wideband (UWB) Multilayer Slotline Power Divider With Bandpass Response

A novel ultra-wideband (UWB) multilayer slotline power divider with bandpass filtering response is presented. In the proposed structure, a single isolation resistor is properly placed between the two output ports. Based on the transmission-line equivalent-circuit method, the design equations of the proposed UWB power divider has been derived with the even and odd mode analyses. Experimental results show that excellent impedance matching at all three ports, amplitude and phase balance at the two output ports, isolation between the two output ports, and out-of-band rejection are observed at the UWB band.      

DFIG-Based Power Generation System With UPS Function for Variable-Speed Applications

The power generation system with a doubly fed induction generator (DFIG), which can be used as an autonomous power system after the loss of mains in a distributed generation network, is described. After the mains outage, a fixed frequency and an amplitude of the output voltage are obtained, despite the variable rotor speed. For this reason, it can be successfully applied in the variable-speed wind turbines, adjustable speed water plants, or diesel engines. Moreover, the stand-alone operation of DFIG is useful in a flywheel-based high-energy rotary uninterruptible power supply system. An output voltage is controlled directly by the synchronization of an actual voltage vector with the reference vector represented in a synchronously rotating polar frame. The rotor current angular speed is obtained as a result of vectorial phase-locked loop operation. Any sensors or estimators of the rotor speed or position are unnecessary. Both amplitude and angle control loops are linear. The use of stand-alone operation in grid-connected systems requires mains outage detection. Also, the grid voltage recovery requires a method of synchronization and soft connection of a generator to the grid. The proposed methods of output voltage control, synchronization, and detection of mains loss were tested in a laboratory system.      

A Novel Photonic Microwave Filter With Infinite Impulse Response

A novel design of a photonic microwave filter with infinite impulse response is presented and demonstrated experimentally, ft overcomes the problems due to optical coherence. The design exhibits substantial flexibility, permitting easy and continuous tunability of the free spectral range. In particular, when a Mach-Zehnder modulator is used in the filter, the passband of the filter response can be changed to stopband and vice versa. The design also provides scope for cascading more stages. Theoretical analysis and measured results are presented, showing a very good match between them.     

大功率智能快速充电机

文章以大功率开关电源作为充电电源,利用单片机来调节充电电压和电流、控制充放电脉冲、完成充电电池组的检测和保护,从而实现铅酸蓄电池的快速充电,提高充电效率。充电过程以马斯定律为指导,采用大电流脉冲充电;并利用短时间的停止充电来解决离子扩散速度低于化学反应速度的问题,减小浓差极化;同时脉冲放电可以使积累在正负极板上的电荷迅速消失,电化学极化也得以控制。     

一种用于大功率D类功率放大器的快速启动LDO

D类放大器的输出级晶体管始终工作在开关模式,效率很高,在便携式电子领域得到广泛应用.采用CSMC 0.5 μm BCD工艺,设计了一款应用于大功率D类放大器的低压差线性稳压器,对其结构和工作原理进行分析,重点讨论了各个关键电路模块的设计,改善了电源抑制比和启动时间.LDO的PSRR为100 dB @ 1 kHz,启动时间18 μs,负载能力225 mA,工作电压范围5.5～18 V,最小压差0.5 V,温度系数54×10-6/℃.     

Dynamic Performance of an APWM Resonant Inverter for High Frequency AC Power Distribution System

In this paper, the feedforward and feedback control loops are designed for the asymmetrical pulsewidth-modulated (APWM) resonant inverter to achieve fast transient response for the application in high frequency ac power distribution systems. In the proposed control scheme, the modulated integral control acts as a feedforward loop and provides pre-regulation for the feedback loop. As a result, the APWM resonant inverter has fast transient response against the line and load variation. Simulation and experimental results are presented to prove the dynamic performance of the APWM resonant inverter