Design and Simulation of Solid State Pulser with Fast Rise Time and Double-exponential Waveform

Voltage pulses with fast rise time can be obtained from Marx circuits based on avalanche transistors. In this research, the ZETEX avalanche transistors are used as the switches in a Marx circuit to generate stable voltage pulses with double-exponential waveform and fast rise time. By using these transistors, the circuit is able to generate higher pulsed voltage with fewer stages. A three stages and a ten stages Marx circuit, as well as their triggering circuits, are designed. The two Marx circuits are also tested by simulations based on the Pspice code and by experiments, results of which are consistent with each other. With the ten stages Marx circuit, we obtain positive and negative pulses with the rise time of about 1.5 ns, the amplitude above 1 100 V, and the pulse width below 5 ns. It is proved that the proposed Marx circuit equipped with avalanche transistors could be an effective kind of solid-state pulse generator.     

新型半导体隔离式高功率因数开关电源

提出一种以半导体开关作为隔离元件、电容器作为功率传输元件的高功率因数开关电源新型拓扑结构,通过控制半导体开关,使电容器交替充放电对负载供电,从而实现物理意义上的隔离。通过对电容器充电回路开关管进行控制,实现交流输入端的高功率因数。与传统的乘法器boostPFC控制电路不同,该装置采用单周期控制,不需要同时检测输出电压和输入电流及电压,无需乘法器。试验研究表明装置稳定可靠,有效地实现了负载与供电网侧的电气隔离。     

风光互补发电中蓄电池智能脉冲充电技术研究

本文介绍一种应用在风光互补发电系统中的智能型正负脉冲充电技术。提出了一种蓄电池充放电电路拓扑结构和控制策略,实现对蓄电池正负脉冲充电,这对提高蓄电池的充电效率和提高蓄电池的使用寿命具有十分重要的意义。     

基于模块化多电平变换器的负序电流补偿系统研究

针对三相负载不平衡引起的负序电流,提出了基于模块化多电平变换器MMC(modular multilevel converter)进行补偿的方案,讨论了其工作特性,提出了相应的控制策略。首先,通过把三相不平衡负载等效为平衡负载的方法,推导出对补偿系统控制的基本要求,明确了补偿的基本原理;然后,分析了补偿系统输入功率特性,提出了MMC用于负序补偿时的等效模型,并分析了环流及电容电压的波动特性,指出三相电容电压之和必定存在二次谐波波动;引入正负序坐标系分离控制的控制策略;最后通过仿真和实验验证了文中提出的结论和控制策略。     

基于PWM+PFM控制的两级DC-DC变换器效率优化

为了提高LLC谐振变换器宽输入电压范围和解决轻载时损耗大导致整体效率不高的问题,基于Boost-LLC两级式拓扑,提出一种全负载范围数字控制效率优化方法.根据不同的负载对前后两级建立双环控制,前级升压Boost电路通过脉宽调制(PWM)方式实现不同负载对应调整输出电压大小,并将其值作为后级LLC电路的母线电压;后级LL...     

新跨接双极三电平子模块拓扑及其控制策略

基于半桥型子模块拓扑的模块化多电平换流器不具备直流短路故障电流阻断能力,影响了低成本架空线的应用.为抑制直流故障时的短路电流,研究了 一种新跨接单极三电平子模块拓扑,解决了混合拓扑中电容不均衡充电问题.然后为应对子模块闭锁对换流站和电网可能产生的不利影响,设计了 一种新跨接正、负极三电平子模块拓扑,并分析了其过调制运行...     

PWM方式串联谐振CCPS研究

PWM方式串联谐振是串联谐振电容器充电电源(CCPS)电路的3种工作模式之一。这种软开关技术是近年来研究的一大热点。为了研究PWM方式串联谐振CCPS电路的工作过程,给出了其电路原理图及各阶段的等效电路,建立了该电路的数学模型。结合数学表达式,通过数学仿真的方法,给出了输出电压变化情况下谐振电路的工作状态,并给出了该电路主要波形。实验结果验证了所采用控制方案的正确性和充电系统的有效性。     

一种基于耦合电感的非对称脉冲电路

在等离子电解氧化过程中采用非对称双极性脉冲可有效避免单极性脉冲所导致的单向极化效应,具有优化膜层结构和改善膜层性能的作用。现有非对称双极性脉冲电路往往需要两台直流源,结构复杂、成本高,并且存在环流问题,为此,提出一种基于耦合电感的非对称脉冲电路拓扑,采用单直流源供电,结构简单,利用耦合电感的储能和电压变换特点实现正脉冲输出和反极性的负脉冲输出。介绍该电路拓扑的工作原理,分析各个模态的工作波形,并推导相应的表达式。仿真和实验结果证明了该电路的可行性,在此基础上进一步进行等离子电解氧化的膜层性能分析,表明该电路对等离子电解氧化膜层性能改善有效。     

一种适用于直流配电网的双向稳压型电压平衡器

直流配电网是一种新型供电系统,面对三线制直流配电网中负荷不平衡问题及其需为用户端提供稳定可靠供电的要求,提出一种适用于新型直流配电网的双向稳压型电压平衡器。将双向稳压Buck/Boost电压转换电路运用于电压平衡器之中,这样不仅能解决三线制网络中正负极电压平衡的问题,而且可以实现平衡输出端电压波动,维持输出端的电压稳定。首先针对该双向稳压型电压平衡器进行数学建模分析,利用状态平均法建立小信号状态模型;之后基于所提出的平衡器特性与其建模分析,在双向互补脉冲宽度调制（pulse width modulation,PWM）控制技术的基础上提出并分析控制策略;最后利用PSCAD仿真软件进行存在电压波动与不平衡负荷情况下的2种负荷类型的稳压平衡器仿真验证,仿真结果验证了其稳压及平衡电压能力,说明了理论分析的正确性。     

同步整流式三端口半桥变换器

提出一种适用于独立新能源供电系统的同步整流式三端口变换器拓扑。该拓扑形式与同步整流半桥变换器相同,蓄电池并联于分压电容,变压器同时用作储能电感,同步整流支路为此电感一变压器的电流提供续流回路;原边两开关管相互独立控制,实现三个端口之间的功率控制,并且任意两端口之间均为单级功率变换;详细分析变换器的工作状态、原理和电路模态,实验验证了拓扑及理论分析的正确性。将拓扑构成和控制思想推广,进一步提出其它形式的三端口和多端口半桥变换器。     

A repetitive high voltage pulse adder based on solid state switches

A repetitive high voltage pulse adder based on solid state switches with isolated recharge is described. All capacitors in the modulator are recharged separately through a corresponding magnetic core transformer by a common high frequency power supply. This circuit configuration simplifies the insulation design and arrangement. This scheme is suitable for high frequency pulse discharge due to its high charge efficiency. At the same time it retains the inherent switch protection capability similar to a solid-state Marx modulator. In our present work, a 22-stage test modulator has been built and successfully operated at output voltage of 20 kV with repetitive rate of 20 kHz, rise time of 150 ns and pulse width of 3 ?s. The primary experiments verified the system feasibility.     

Circuit Analysis and Characterization of Contactless Power Transfer System with Variable Impedance

A contactless power transfer system using a repeater coil (repeater Coil topology) has been proposed as a method of suppressing overcurrent without power control during misalignment or no‐load. By installing a repeater coil between the primary and secondary coils, it is possible to increase the input impedance in the case of misalignment of the secondary coil or no‐load condition. In addition, another contactless power transfer system using primary parallel and secondary series resonance capacitors (PS capacitor topology) has been proposed. In the PS capacitor topology, the input impedance can be increased during misalignment of the secondary coil or no‐load condition similar to the repeater coil topology. In this paper, we evaluated the characteristics of both these topologies. First, we conducted a circuit analysis of the repeater coil topology and proposed a design method. In addition, we theoretically clarified the characteristic difference of the two topologies and experimentally evaluated the characteristics.     

正负脉冲式高频开关电源的研究

针对电池在充电过程中,电池内部产生的气体严重影响电池的使用寿命和容量的情况,提出了在充电过程中,可以通过瞬间放电把电池内部的气体排出的正负脉冲式充电方法。给出了正负脉冲式高频开关电源的电路拓扑结构及控制方法,采用新技术提高系统的功率因数。通过试验验证了该方法在提高电池有效容量和缩短电池充电时间方面有了明显的改善。     

单极性电流控制半桥电压平衡电路研究

电压平衡电路不但可以将两线制直流微网转变成三线制直流微网,而且还可以应用在平衡串联电容或电池组电压等场合。半桥电压平衡电路具有结构简单、成本低廉等优点。但是,在互补驱动条件下,当电感电流工作在双极性时存在无功电流。因此,在前期研究基础之上,提出了单极性电流控制方法,详细地分析了单极性控制下半桥电压平衡电路工作原理。仿真和实验结果表明,在单极性控制下半桥电压平衡电路能够有效地实现输出电压均衡功能,并消除无功电流。     

多断口真空断路器均压电容研究综述

由于杂散电容的影响,多断口真空断路器的电压分布是不均匀的,但是目前尚无针对多断口真空断路器的均压电容选择方法.笔者对多断口真空断路器均压电容的研究现状进行了综述,总结了均压电容对提高多断口真空断路器开断能力的积极作用和可能带来的负面效应,并对积极作用以及负面效应的产生机理进行了分析.指出了现有研究的局限性,并进行了初步...     

A novel step-up topology for multilevel power conversion

Renewable energy sources employ a power conditioning unit for injecting power into the grid. Such resources of small capacity are characterized by low generated voltage and thus require a high voltage boost at the inversion stage. This paper proposes a novel transformer-less, single-phase grid-connected, 13-level inverter to yield the voltage boost. The presented topology is realized through 12 unidirectional switches, 2 diodes, and 3 capacitors. A single-stage circuit synthesizes 13 levels with a single input source and yielding an overall voltage gain of six. The adapted modulation technique is robust enough to keep the capacitors self-balanced for all values of the modulation index. The proposed topology is modular and cost-effective in comparison to other similar typologies due to reduced device count and space requirement. The presented topology is validated experimentally with satisfactory operation in yielding input voltage boost by a factor of six.     

基于现场可编程门阵列的全固态高压ns脉冲发生器

为研究ns脉冲电场诱导肿瘤细胞的凋亡效应,结合Marx发生器原理和全固态开关技术,研制了一套基于现场可编程门阵列(FPGA)的多参数可调全固态高压ns脉冲发生器。该发生器主要包括高压直流电源、Marx电路、FPGA控制电路和负载4部分。Marx电路采用金属氧化物半导体场效应晶体管(MOSFET)作为控制开关代替传统的火花间隙开关,用二极管代替电阻。FPGA产生多路同步触发脉冲信号,通过光纤进行隔离后可作为MOSFET的原始控制信号,同步驱动多个MOSFET。FPGA控制电路控制充电电压和输出脉冲的宽度、频率,并具有保护功能。实验结果表明,该脉冲发生器可产生幅值(0～8kV)连续可调、脉宽(200～1 000ns)灵活可变、频率(1～1 000Hz)独立可控,前沿35ns的高压ns脉冲,为进一步探索ns脉冲电场生物医学效应奠定了基础。     

LLC resonant DC–DC converter with series‐connected primary windings of transformer

This paper proposes a zero‐voltage switching (ZVS) LLC resonant step up DC–DC converter with series‐connected primary windings of the transformer. The series resonant inverter in the proposed topology has two power switches (MOSFETs), two resonant capacitors, two resonant inductors, and only one transformer with center‐tapped primary windings. The power switches are connected in the form of a half‐bridge network. Resonant capacitors and inductors along with the primary windings of the transformer form two series resonant circuits. The series resonant circuits are fed alternately by operating the power switches with an interleaved half switching cycle. The secondary winding of transformer is connected to a bridge rectifier circuit to rectify the output voltage. The converter operates within a narrow frequency range below the resonance frequency to achieve ZVS, and its output power is regulated by pulse frequency modulation. The converter has lower conduction and switching losses and therefore higher efficiency. The experimental results of a 500‐W prototype of proposed converter are presented. The results confirm the good operation and performance of the converter. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

新型电感储能型电磁炮脉冲电源拓扑

提出了一种用于电磁发射的电感储能型电磁炮脉冲电源拓扑。该拓扑中两储能电感充电时串联,放电时并联,以实现电流倍增。与meatgrinder电路相比,该电路两储能电感之间不需要磁耦合,具有设计简单灵活、容易制造的特点。为避免电感储能断路时断路开关出现过电压问题,用电容作为能量转换器件可实现开关的零电压断路。对该脉冲电源系统的工作原理进行了理论分析,搭建了小型实验系统,验证了该电源拓扑的可行性。以轨道炮为负载,对电感、电容参数对系统性能的影响进行了仿真分析,结果表明多个电源模块的并联运行能明显提高系统能量转换效率。     

Trans Z-source-based half-bridge inverter: A method for achieving high voltage gain

This article offers a modified trans Z-source-based half-bridge inverter topology. A suitable pulse width modulation (PWM)-based control method is applied on the proposed inverter. Regarding this control technique, the state of switches in each of the operational states is obtained, and their equivalent control circuits are demonstrated and examined in depth. With the help of the results of these analyses, the boost factor for the proposed structure can be calculated. Additionally, the necessary equations for designing the passive components, as well as the power ratings of the active components, are found. Then, in order to evaluate the advantages and disadvantages of the proposed topology, a comparative study is conducted in several aspects, including the boost factor, the voltage stresses on capacitors, and the voltage stresses on passive devices. This comparison demonstrates that the proposed topology provides a high boost factor while minimizing voltage stresses on the devices, resulting in a smaller volume and size and a lower cost. Once the proposed topology has been thoroughly analyzed, the total power losses and the percentages of power losses consumed by each component device are calculated to obtain efficiency. Finally, an experimental prototype based on the equations for passive and active components is developed. Experiments are used to verify the validity of the proposed topology and the accuracy of the equations.