基于Switch-Capacitor网络实现分时供电的多输入升压变换器

在新能源联合发电系统中,多输入直流变换器可分时或同时向负载提供能量,具有简化系统结构、降低系统成本等优点。然而,现有的多输入直流变换器不能很好地满足新能源发电领域对高升压比、低纹波、低开关应力等技术参数的要求。因此,本文基于Switch-Capacitor网络串联放电、并联充电和多个网络累加升压的工作特性,推导出一种新型多输入升压变换器。本文以三输入升压变换器为例,详细分析了其在连续工作模式下的工作原理和工作性能,进行了仿真分析,并搭建了实验模型,仿真分析与实验研究的结果表明:①升压能力强,其升压比与Switch-Capacitor网络组中的网络个数有关;②开关器件的电压应力、输入电流纹波和输出电压纹波小;③所有开关管由同一控制信号隔离驱动,控制电路简单;④实现分时供电,元器件利用率高;⑤推演出对应的同时供电多输入升压变换器。

Waveform digitization utilizing switched-capacitor arrays

Compared with traditional waveform digitization with flash-ADCs, waveform digitization with switched-capacitor arrays (SCAs) is able to achieve the sampling speed above 1 GS/s without degrading the analog to digital conversion precision significantly. In this paper, we present the implementation of a fast waveform digitization system with the use of SCAs, and evaluate its performance of waveform digitization and the waveform timing. At about 5 GS/s, the dynamic input range of the digitizer is about 66 dB, and its timing precision is about 20 ps (RMS).

NOVEL LINEAR TRANSFORMATION SWITCHED-CAPACITOR FILTER DESIGN

This paper presents a novel method that is applied to realize the Linear Transformation(LT)Switched-Capacitor Filter(SCF).It adopts the Voltage Control Voltage Source(VCVS)equalized transfor-mation to revise the original LC ladder filter and induce it into 16 basic sections and then extend the princi-ple of the LT in order to fit active and 3 port networks and give out switched-capacitor circuits corre-sponding to the 16 basic sections,which can realize all four kinds of filters——LP,HP,BP,BS filters.De-signed examples are given here.An Nth order filter only requires N amplifiers and the circuit is insensitive toparasitic capacitances.The experimental results of a 3rd order elliptic LP and a 6th order elliptic BP are giv-en and agree with the theory.

Design of Sixth-Order Lowpass Elliptic Switched-Capacitor Filter

In this paper the design and implementation of sixth-order lowpass elliptic switched-capacitor filter( SCF) for interface circuit of Micro-Electro-Mechanical System( MEMS) sensor are presented. This work aims to lower total harmonic distortion( THD) without deteriorating other performances. After system design in Simulink,the filter is realized in transistor level and finally fabricated in Central Semiconductor Manufacturing Corporation( CSMC) 0.5 μm metal-oxide-semiconductor( CMOS) technology. Typical measured results are: it operates with 25: 1 clock-to-corner frequency ratio and a 10 k Hz maximum corner frequency. The maximum passband ripple is about 0.49 d B and the minimum stopband rejection is 40 d B for the temperature from-20 ℃to 80 ℃. For the 250 k Hz clock frequency setting,given the 1 k Hz,- 8 d BVrms input signal,the measured worst case THD is-64 d B. The active area of the chip is 2.8 mm2 with 8 pads. The analog power dissipation is10 m W from a 5 V power supply.

Design of a Switched Capacitor Negative Feedback Circuit for a Very Low Level DC Current Amplifier

To miniaturize a very low level dc current amplifier and to improve its output response speed, the switched capacitor negative feedback circuit (SCNF), instead of the conventionally used high-ohmage resistor, is presented in this paper. In our system, a switched capacitor filter (SCF) and an offset controller are also used to decrease vibrations and offset voltage at the output of the amplifier using SCNF. The theoretical output voltage of the very low level dc current amplifier using SCNF is obtained. The experimental results show that the unnecessary components of the amplifier’s output are much decreased, and that the response speed of the amplifier with both the SCNF and SCF is faster than that using high-ohmage resistor.

Tunable Bandwidth Third Order Switched-Capacitor with Multiple Feedbacks Filter for Different Center Frequencies

This paper proposes third order tunable bandwidth active Switched-Capacitor filter. The circuit consists of only op-amps and switched capacitors. The circuit is designed for circuit merit factor Q = 10. The proposed circuit implements three filter functions low pass, band pass and high pass simultaneously in single circuit. The filter circuit can be used for both narrow as well as for wide bandwidth. For various values of cut-off frequencies the behaviour of circuit is studied. The circuit works properly only for higher central frequencies, when f0 > 10 kHz.

Switching of Capacitors in an Asymmetric Induction Motor with Single-Phase Power,Triggering Several Applied Loads

xThis study has as its objective to collaborate with the expansion in the market of electric energy in rural areas,offering as such an innovative prospect to the solution of associated problems through use of the asymmetric three-phase induction motor,supplied by a single-phase source.In this system,capacitor switching is applied during operation,while theoretical and practical results are presented for the application of this switching in a three-phase asymmetric induction motor of 20 hp.

A Novel Dual-Rate Sampling Switched-Capacitor Configuration and Its Application

In order to realize accurate bilinear transformation from s- to z-domain,a novelswitched-capacitor configuration is proposed in the light of principles of dual-rate sampling and chargeconservation,which has also been used for building a 5th-order elliptic lowpass filter.The filter issimulated and measured in typical 0.34 μm/3.3 V Si CMOS process models,special full differentialoperational amplifiers and CMOS transfer gate switches,which achieves 80 MHz sampling rate,17.8MHz cutoff frequency,0.052 dB maximum passband ripple,42.1 dB minimum stopband attenuation and74 mW quiescent power dissipation.At the same time,the dual-rate sampling topology breaks thetraditional restrictions of filter introduced by unit-gain bandwidth and slew rate of operational amplifiersand also improves effectively their performances in high-frequency applications.It has been applied forthe design of an anti-alias filter in analog front-end of video decoder IC with 15 MHz signal frequencyyet.

Multi-Phase QR ZCS Switched-Capacitor Bidirectional Power Converter for PV System Application

The multi-phase implementation in the QR （quasi resonant） ZCS （zero current switching） SC （switched capacitor） bidirectional DC-DC converter structure has been proposed to reduce current ripple, switching loss and significantly increase the converter efficiency and power density. This approach provides a more precise output voltage to obtain voltage conversion ratios from the double-mode versus half-mode to n-mode versus 1/n mode. This is accomplished by adding a different number of switched-capacitors and power MOSFET switches with a small series connected resonant inductor for forward and reverse schemes. The size and cost can be reduced when the proposed converter has been designed with the coupled inductors. The simulation and experimental results have been used to demonstrate the performance of the two-phase with and without coupled inductor interleaved QR ZCS SC converters for bidirectional power flow control application, and an extending structure for N-phase is mentioned.

Direct on Line Starting Induction Motor with Thyristor Switched Capacitor Based Voltage Regulation

The purpose of this paper is to show a laboratory scale implementation of a Thyristor Switched Capacitors （TSC） as an alternative for voltage regulation during a direct on line three-phase induction motor starting on an emulated weak transmission line. Thyristor switched capacitor bank was chosen because it is a well known topology, considering the very nature of the direct starting induction motors, which represents a highly inductive load, the use of switched reactors becomes unnecessary. Such fact minimizes the introduction of harmonics components, and also reduces the cost of the implementation. The binary disposition of the banks allows a variable Var compensation with sixteen steps, in this case. The solution makes use of low cost devices combined with sliding window voltage and current measurement algorithm and a PI control with dead band control for achieve the shown experimental results, where the system is able to manage a typically 20% voltage drop, reducing it to less than 4%. The schematic of the developed circuit, the control technique and a quite simple method to calculate the binary weight capacitors banks are also presented.

A High-Performance Operational Amplifier for High-Speed High-Accuracy Switch-Capacitor Cells

A high-speed high-accuracy fully differenttial operational amplifier （op-amp） is realized based on no-Miller-capacitor feedforward （NMCF） compensation scheme. In order to achieve a good phase margin, the NMCF compensation scheme uses the positive phase shift of left-half-plane （LHP） zero caused by the feedforvvard path to counteract the negative phase shift of the non-dominant pole. Compared to traditional Miller compensation method, the op-amp obtains high gain and wide band synchronously without the pole-splitting effect while saves significant chip area due to the absence of the Miller capacitor. Simulated by the 0.35 μm CMOS RF technology, the result shows that the open-loop gain of the op-amp is 118 dB with the unity gain-bandwidth （UGBW） of 1 GHz, and the phase margin is 61°while the settling time is 5.8 ns when achieving 0.01% accuracy. The op-amp is especially suitable for the front-end sample/hold （S/H） cell and the multiplying D/A converter （MDAC） module of the high-speed high-resolution pipelined A/D converters （AVCs）.

一种适应于直流微电网的全桥LLC变换器

针对传统的光伏并网隔离型变换器的变压器体积大、损耗高和半导体器件电压应力高等问题,提出一种基于LLC谐振变换器的高增益DC-DC变换器。该变换器满足了输入输出之间电气隔离的要求,将全桥LLC谐振变换器与开关电容相结合,有效地提高了变换器的增益,减少了变压器的体积和损耗,降低了半导体器件的电压应力,实现了开关管的零电压开通和二极管的零电流关断,有效地降低了开关损耗。首先对所提变换器的工作原理进行详细分析;其次用基波分析法分析其基本特性,并进行半导体器件电压、电流应力计算及电路的参数设计;最后搭建一台了800 W的实验样机,经过实验验证,该变换器实现了开关管的ZVS开通,二极管的ZCS关断;减小了变压器的体积和铜耗;转换效率最高可达94.9%。二次侧二极管的电压应力为输出电压的12,是全桥整流的0.5倍、半桥整流的0.25倍,且平均电流相同,有利于器件的选型,更适用于直流微电网的应用,证明了理论分析的准确性。

双向CLLC谐振变换器开关管开路故障特性分析

为研究双向CLLC谐振变换器发生开关管开路故障特性,首先介绍双向谐振变换器CLLC的拓扑与基本原理,分析开关管开路故障后暂态特性6种模态及稳态特性4种故障模式的特点,并利用模态分析法进行建模。在此基础上对CLLC变换器故障后的电压增益、谐振电流应力与谐振电容电压应力进行研究,并与DBSRC变换器发生开关管开路故障时的故障特性进行对比分析。最后,通过仿真与实验验证了故障特性分析的准确性。

基于可编程非线性补偿的斜坡电压发生器

恒定斜率的线性斜坡电压经过电容后,可以生成小于1 nA的校准电流,而电流的稳定性很大程度上取决于斜坡电压发生器的性能。文中提出一种基于可编程非线性补偿的斜坡电压发生器,采用可控电流源对电容进行充电,获取非线性补偿信号,并结合多个模拟开关实现两个相同通道的交替补偿,从而生成更加平滑的斜坡电压。与过去基于两个数模转换器的斜坡电压发生器相比,所提发生器大大缩短了补偿时间,扩展了斜率的可调范围;同时,通过电容充电生成的线性斜坡克服了数模转换器补偿信号非线性的问题。实验结果表明,所提的基于电容充电非线性补偿方法的斜坡电压发生器在斜率控制和斜坡平滑性方面的表现均优于数模转换器的补偿方法,并且经过电容充电非线性补偿后的斜坡电压平滑性相对提升了80.4%。

基于Switched-RC技术的0.8V带通滤波器

开关电容滤波器是信号处理系统的重要组成模块，设计了一种用于心率检测设备的六阶带通开关电容滤波器。该设计基于开关电阻电容技术，利用开关电阻代替传统的采样开关，实现了更高的采样线性度，是低压下开关电容滤波器正常工作的一种全新实现方案。仿真结果表明，该滤波器在0.8V工作电压下，功耗为0.9mw，输出摆幅可达1.2Vp-p，通带增益为10dB，-3dB带宽为25-80Hz。

A Design of the Elliptic Switched Current Filter

In conformity with a fifth order RLC elliptic filter circuit prototype, it is easy to conceive the corresponding RC active filter circuit. Simple and feasible method presented here can be used to contrive the equivalent switched capacitor filter circuit and switched current filter circuit. Consulting the technique data manual, we can expediently design a specific RLC filter. Therefore, it is of great convenience to design the switched current filter, which has the same performances. Such a kind of technology is useful in the domain of analogue sampled data signal processing.

Genetic Algorithm Based 7-Level Step-Up Inverter with Reduced Harmonics and Switching Devices

This paper presents a unique voltage-raising topology for a single-phase seven-level inverter with triple output voltage gain using single input source and two switched capacitors.The output voltage has been boosted up to three times the value of input voltage by configuring the switched capacitors in series and parallel combinations which eliminates the use of additional step-up converters and transformers.The selective harmonic elimination(SHE)approach is used to remove the lower-order harmonics.The optimal switching angles for SHE is determined using the genetic algorithm.These switching angles are com-bined with a level-shifted pulse width modulation(PWM)technique for pulse generation,resulting in reduced total harmonic distortion(THD).A detailed com-parison has been made against other relevant seven-level inverter topologies in terms of the number of switches,drivers,diodes,capacitors,and boosting facil-ities to emphasize the benefits of the proposed model.The proposed topology is simulated using MATLAB/SIMULINK and an experimental prototype has been developed to validate the results.The Digital Signal Processing(DSP)TMS320F2812 board is used to generate the switching pulses for the proposed technique and the experimental results concur with the simulated model outputs.

A Novel Single Switch High Gain DC-DC Converter Topology for Renewable Energy Systems

Renewable energy with sources such as photovoltaic(PV)or fuel cells can be utilized for the generation of elec-trical power.But these sources generate fewer voltage values and therefore require high gain converters to match with DC bus voltage in microgrids.These high gain converters can be implemented with switched capacitors to meet the required DC bus voltage.Switched capacitors operate in a series and parallel combination during switch-ing operation and produce high static gain,limits reverse voltage that appears across the components.A novel converter is proposed that satisfies all the features such as high voltage gain,only one switch,forces less potential stress cross the components,ripple current is less.These features of the proposed converter are verified through MATLAB/SIMULINK.

HIGH SELECTIVITY SC BANDPASS FILTERS WITH LESS CAPACITOR SPREAD

Two novel switched-capacitor(SC)bandpass filters using a single operational am-plifier(op amp)are presented.Optimal designs for minimizing capacitor spread are also given.Gain-bandwidth product(GB)effects of op amps on the proposed SC circuits are taken intoconsideration.Comparisons with the proposed circuits and the circuits given by the literatureshow that the new circuits require less chip area in monolithic integration and are less sensitiveto the GB effects.

The Impact of the Offshore Wind Farm Switching Transient Operation on Power System

In this paper, a practical method to establish Doubly Fed Induction Generator (DFIG) based wind farm equivalent model for switching transient analysis is demonstrated. In order to verify this method, a 3.6MW equivalent wind farm model is built. The steady state results and load switching results are verified with those of detailed models of four 0.9MW generators. Using this method, a model of 40MW wind farm, representing the capacity for a proposed South Carolina offshore wind farm is established. To study large wind farm switching transient impacts on a system, different switching operations such as cable energizing and three phase faults at different locations in wind farm are investigated and their impact on system are analysed. Finally, conclusions based on the switching cases are presented.