Status and Opportunities of Zinc Ion Hybrid Capacitors: Focus on Carbon Materials, Current Collectors, and Separators

Zinc ion hybrid capacitors(ZIHCs), which integrate the features of the high power of supercapacitors and the high energy of zinc ion batteries, are promising competitors in future electrochemical energy storage applications. Carbon-based materials are deemed the competitive candidates for cathodes of ZIHC due to their cost-effectiveness, high electronic conductivity, chemical inertness, controllable surface states, and tunable pore architectures. In recent years, great research efforts have been devoted to further improving the energy density and cycling stability of ZIHCs. Reasonable modification and optimization of carbon-based materials offer a remedy for these challenges. In this review, the structural design, and electrochemical properties of carbon-based cathode materials with different dimensions, as well as the selection of compatible, robust current collectors and separators for ZIHCs are discussed. The challenges and prospects of ZIHCs are showcased to guide the innovative development of carbon-based cathode materials and the development of novel ZIHCs.

Reliability of DC-link capacitor in pulsed power supply for accelerator magnet

Capacitors are widely used in pulsed magnet power supplies to reduce ripple voltage,store energy,and decrease power variation.In this study,DC-link capacitors in pulsed power supplies were investigated.By deriving an analytical method for the capacitor current on the H-bridge topology side,the root-mean-square value of the capacitor current was calculated,which helps in selecting the DC-link capacitors.The proposed method solves this problem quickly and with high accuracy.The current reconstruction of the DC-link capacitor is proposed to avoid structural damage in the capacitor’s current measurement,and the capacitor’s hotspot temperature and temperature rise are calculated using the FFT transform.The test results showed that the error between the calculated and measured temperature increases was within 1.5℃.Finally,the lifetime of DC-link capacitors was predicted based on Monte Carlo analysis.The proposed method can evaluate the reliability of DC-link capacitors in a non-isolated switching pulsed power supply for accelerators and is also applicable to film capacitors.

currentMKMJ25-22型自愈式脉冲电容器耐久性试验条件的验证及其重要意义

随着电力装备制造技术的不断提升,自愈式脉冲电容器作为一种关键的电子元器件,在多个领域的应用逐渐得到广泛推广。为了确保这些电容器在实际应用中的稳定性和可靠性,必须对其进行严格的耐久性试验。然而,目前主流的试验方法尚不能准确快速地反映MKMJ25–22型自愈式脉冲电容器的实际性能。针对MKMJ25–22型自愈式脉冲电容器的试验问题,文章对标行业试验标准,对试验设备的能力进行了理论分析,并在元件选取、充放电回路等方面对试验回路进行了优化设计。通过对1台MKMJ25–22型自愈式脉冲电容器进行2000次的耐久性试验,证明回路、设备、配件均能够满足MKMJ25–22型自愈式脉冲电容器的试验要求。

A NOVEL CONTROL STRATEGY FOR SINUSIODAL WAVE INVERTER WITH PI REGULATORS AND CAPACITOR CURRENT FEEDBACK

Objective For the inverters used in UPS, it is important to maintain the pure sinusoidal AC output voltage waveform over all loading conditions and transients. Methods A novel sinusoidal output voltage control strategy is pregented in this paper. The output voltage is controlled by introducing filtering eapacitor current feedback. Two simple PI regulators are used for the current and voltage control loops. Results With the new control strategy, the inverter achieves very low output voltage distortion, good output voltage regulation and strong perturbation rejection, fast dynamic response, and good performance under nonlinear loads. The THD under capacitance rectifying load is better than 0.2%, the output voltage regulation within 0 to full load is less than 0.1%. The resting time under load transient is within 200?μ s . Conclusion The merits of the new control strategy include rapid response and good steady state stiffness.

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.

Active Current Sharing of LCLC Resonant Converter with Switch-Controlled-Capacitor Technology

In this paper,an interleaved LCLC converter with enhancement-mode(E-mode)GaN devices is introduced to achieve the accurate current sharing performance for data center applications. Any tolerance in the resonant tank elements can lead to large load imbalance between any two different phases. Due to the steep gain curves of LCLC converters,conventional current sharing methods are not effective. In the proposed converter,the impedances of the resonant networks are matched by switching a capacitor,i.e.,switch controlled capacitor(SCC),in series with the resonant capacitor in one or some of the phases,which results in accurate load current sharing among the phases with an accuracy around 0.025%. The load share of a phase is sensed through the resonant current on it,and the control logic applied to such current sharing can be achieved. By this method,accurate current sharing is achieved for a wide input voltage range required for the hold-up time in data center applications. Interleaving is applied in the proposed multiphase LCLC converter,resulting in low current stress on the output capacitor and allowing ceramic capacitor implementation. Moreover,phase shedding accomplishes high light load efficiency. The performance of the proposed interleaved LCLC converter is verified by a two-phase 1 k W prototype with an input voltage ranging from 250 V to 400 V and a fixed 12 V output voltage.

磁脱扣器动作响应分析及储能电容匹配设计

驱动电路与磁脱扣器是电磁式漏电保护器的核心组件,磁脱扣器需与储能电容匹配。在电磁式漏电保护器基本工作原理分析的基础上,建立磁脱扣器的数学模型与有限元计算模型,根据激磁安匝变化进行衔铁响应状态分析,仿真不同线圈激励形式下磁脱扣器动作响应状态。研究衔铁角动量与角位移变化特征,根据无激励时衔铁释放临界角动量与角位移关系,确定不同线圈激励形式下的衔铁临界释放条件。研究电容电压激励源下衔铁所受力矩冲量的变化规律,分析电容及其储能对衔铁释放响应状态的影响,根据临界储能最小的原则确定电容匹配,可以降低衔铁可靠释放所需储能。通过对磁脱扣器样机进行实验测试,验证了理论分析与仿真计算的正确性。

一种两倍升压五电平开关电容逆变器

开关电容型逆变器具有使用单直流电源输入、电容电压自均衡、输出谐波含量低以及高电压增益的优势。本文提出一种新型五电平逆变器拓扑,该拓扑由1个直流电源、2个浮动电容、1个电感以及4对互补开关管构成;采用多载波层叠调制策略实现开关电容与输入电源的分时串并联运行;实现了2倍电压增益、五电平输出以及电容电压自均衡;通过增加电感抑制了开关电容充电时存在的脉冲电流,降低了开关管的电流应力。此外,逆变电路中没有单独二极管器件,使得该电路具有能量双向流动的能力,扩展了电路的应用范围。本文详细分析了电路的构成及工作过程,仿真及实验结果验证了所提出的逆变器具有可行性。

基于比例重复控制的MMC-SST子模块电容纹波电压抑制策略

基于模块化多电平变换器的固态变压器(modular multilevel converter based solid state transformer,MMC-SST)是实现交直流混合配电网柔性互联及能量多向流动的关键装备。针对固态变压器输入级MMC子模块电容纹波电压过大,导致装置的体积和成本增加的问题,提出一种基于比例重复控制的MMC-SST改进纹波电压抑制策略。首先利用基于比例重复控制的电容电压闭环得到调整后的功率移相角。然后,通过双有源桥变换器将子模块电容纹波功率传递到低压直流母线,从而有效抑制MMC子模块的各频次纹波电压,达到减小电容值的目的。最后,仿真结果表明在网侧电压对称或不对称工况下,基于比例重复控制的MMC-SST子模块电容纹波电压抑制策略均具有良好的纹波电压抑制能力。

基于LC谐振单元的多回路开关电容型均衡电路

传统的串并联开关电容型均衡电路在工作过程中会产生影响电路可靠性的冲击电流,为了改善该问题对电路性能的影响,同时提升电路的均衡速度,提出一种基于LC谐振单元的多回路开关电容型均衡电路。电路的LC谐振单元由均衡电容串联电感元件组成,所有开关器件均工作在零电流开关模式下,这将有效降低开关损耗,并有效抑制电路中的冲击电流,从而延长开关器件的使用寿命,提高电路的可靠性。所提出的均衡电路采用两个LC谐振单元作为储能元件组的组间均衡支路,可以同时实现储能元件单体与单体之间以及储能元件组与组之间的均衡,在保证均衡精度的同时,有效地提升电路均衡的速度。详细地分析了电路的特点与工作原理,通过搭建仿真平台,将所提出电路与现有的同类型均衡电路对比,验证了所提出均衡电路对均衡速度的提升作用。搭建了五个串联超级电容的实验平台,实验结果表明,所提出的电路可以提升55.85%的均衡速度,并且对冲击电流有显著的抑制作用。

电容电压平衡的四电平有源中性点钳位逆变器的改进模型预测电流控制

多电平有源中点钳位(ANPC)逆变器具有功率器件电压应力小、电流谐波低和器件损耗可调控等优点,被广泛应用于工业驱动中。针对四电平ANPC(4L-ANPC)逆变器的控制与调制研究相对较少,现有的调制方案实现复杂,中点电压(NPV)控制难度较大。因此,该文针对三相4L-ANPC逆变器,提出一种改进的有限集模型预测电流控制(FS-MPCC)算法,避免了复杂的调制过程。首先,使用仅包含电流误差的代价函数对位于六边形顶点的6个大电压矢量进行寻优;其次,对参与第一步寻优的大矢量划分扇区,使用包含电流误差和电容电压误差的代价函数对最优大矢量所在扇区的所有电压矢量滚动寻优,得到目标电压矢量并作用于逆变器;最后,仿真和实验结果表明,与传统的FS-MPCC相比,所提方法在降低系统计算负担的同时,还具有较好的控制性能和电容电压平衡能力。

不平衡电网下模块化多电平换流器的直流环流均衡策略

不平衡电网下模块化多电平换流器(MMC)存在三相直流环流不均衡问题,易导致相间电流应力和热应力差异,降低其在不平衡工况下安全运行能力。该文从桥臂功率角度分析不平衡电网下三相MMC直流环流不均衡现象和基于零序电压注入的直流环流均衡机理。提出一种零序电压注入的直流环流均衡方法,通过网侧电流与直流环流偏差量计算得到零序电压相位,经过比例谐振控制器生成零序电压注入量,进而实现直流环流的快速、有效均衡。在所提出的控制策略的基础上,研究该方法对MMC桥臂电流峰值、有效值及子模块电容电压纹波的影响规律。仿真与实验结果验证了该文理论分析与控制策略的有效性。

感应电能传输系统多并联拾取模块电流和输出功率均衡方法

大功率感应电能传输系统通常采用多并联拾取模块结构。然而,多并联拾取模块参数不一致,会导致各个拾取模块的电流和输出功率不均衡,从而降低系统效率,严重时会因模块过流而造成系统故障。为解决该问题,文中提出一种基于并联拾取模块补偿电容器的多并联拾取模块电流和输出功率均衡方法。首先,介绍了传统感应电能传输系统与所提出的感应电能传输系统拓扑的特性。然后,分别分析了互感、拾取线圈自感及内阻对电流分布和系统效率的影响。最后,通过4个并联拾取模块的感应电能传输系统实验平台验证了所提方法的有效性。实验结果表明,采用所提方法时多并联拾取模块的电流和输出功率基本一致,并且相比传统感应电能传输系统,系统效率最高提升了2.21%。

基于电流应力优化和6脉波调制的双有源桥AC/DC变换器控制策略

针对双有源桥(dual active bridges,简称DAB)AC/DC变换器,该文提出基于电流应力优化和6脉波调制的双有源桥AC/DC变换器控制策略.DAB和三相逆变器(three phase inverter,简称TPI)是双有源桥AC/DC变换器的两个关键单元.对DAB采用电流应力优化,对TPI采用6脉波调制.仿真实验结果表明:相对于单移相(single phase shift,简称SPS)调制策略,该文策略的电感电流的峰值更小,即能更有效地降低电流应力.因此,该文所提策略具有优越性.

一种CC/CV平滑切换的宽输出电压充电电路

目前多种动力蓄电池凭借着能量密度高、续航里程长和可循环使用等优势,在新能源汽车领域得到了广泛应用。针对当前以谐振电路为基础构建复合变换器应用于蓄电池充电存在输出电压范围、模式间切换、效率等不同问题,提出了一种四开关Buck-Boost与电容钳位LLC级联复用式变换器作为充电电路。该电路增益曲线的容性区和感性区均可工作,宽调频范围的容性区具有恒流特性,感性区的最佳谐振点具有恒压特性,利于实现蓄电池恒流恒压充电控制。频率与占空比的解耦控制拓宽了变换器的输出电压范围,且负载阻抗连续变化下电压增益连续,利于实现蓄电池恒流恒压平滑切换及满足不同电池充电控制方案,宽增益下的宽调控范围可减少输出纹波。拥有桥臂间移相软开关、复用桥臂增强软开关能力和降低通态电流、变压器低磁链及最终移动于最佳谐振点工作等电路特性,利于实现电能高效传输。仿真与实验结果验证了充电电路全程满足ZVS、ZCS的恒流恒压控制及充电模式间平滑切换特性。

柔性直流输电用干式直流电容器工况验证试验回路研制

干式直流电容器作为柔性直流输电换流阀的核心组件,尚未开展阀组级工况试验验证。通过对目前实验室条件下换流阀组件运行情况的调研,确定采用被试阀段与陪试阀段对拖运行的拓扑,以满足验证试验回路构建的要求。通过仿真分析和系统试验,证明在满足经济性和实用性要求下,正常工作时回路各阀段至少需要5个子模块串联。考虑到该试验回路需要针对不同型号规格的电容器开展运行试验,叠层母排采用了特殊的设计,方便参数测量和电容器更换。

直流母线小电容永磁同步电机驱动系统网侧电流谐波抑制策略

直流母线采用小电容永磁同步电机驱动系统具有降低成本和延长运行寿命的优势。但在系统运行时网侧电流中存在大量的谐波,这将会影响网侧电流质量。为了改善小电容永磁同步电机(PMSM)驱动系统的网侧电能质量,该文提出一种基于阻抗重塑的有源阻尼控制方法,以抑制网侧电流谐波。通过对驱动系统进行建模,分析影响网侧电流谐波的因素,建立母线电流与网侧电流的数学关系。采用有源阻尼控制方法,提取母线电压谐波信号,以最优电压补偿的方式构建反馈回路,重塑驱动系统的特定频率处的等效阻抗,以实现网侧电流谐波的改善。同时,为了抑制电压补偿模块对电流内环扰动的影响,设计电流环级联双频陷波器,并通过系统极点图进行了稳定性分析。仿真结果和实验分析验证了所提控制方法的有效性。

一种带飞跨电容的单相光伏逆变器

非隔离型逆变器存在的漏电流会增大系统损耗、产生安全隐患。研究了一种带飞跨电容的新型单相光伏逆变器,由5个开关管、一个飞跨电容和一个滤波器构成,结构简单,易于实现。逆变器交流侧与直流侧共地,可完全消除漏电流。针对该新型单相光伏逆变器,采用一种改进的单极性SPWM技术进行控制,优化了各开关管的控制逻辑,所有开关管只在半周期内高频调制,有利于减少开关管损耗。搭建了逆变器的仿真模型和实验样机,仿真和实验结果验证了理论分析的正确性。

基于占空比主动调节的钳位开关电容型DC/DC解耦控制策略

钳位开关电容型DC/DC(Clamping Switched Capacitors-based DC/DC,CSC)是构建具有直流故障自清除能力直流变压器的有效模块。由于传统控制策略下的CSC中直流电压与电容电压存在着耦合效应,直流电压的变化将直接引起电容电压与交流环节电压幅值的变化,使得CSC在两端直流电压不匹配时可能发生软开关丢失、电流应力增大、功率损耗增加等运行性能下降的现象。鉴于此,为改善CSC在直流电压不匹配时的开关及效率性能,提出了一种基于可变占空比的CSC电容电压解耦控制策略。该策略可以在CSC的整个运行范围内保证交流电压幅值的自动匹配,对于改善CSC的整体运行性能具有明显效果。基于试验样机,验证了所提控制策略的正确性与有效性。