An equivalent circuit model for terahertz quantum cascade lasers:Modeling and experiments

Terahertz quantum cascade lasers（THz QCLs） emitted at 4.4 THz are fabricated and characterized. An equivalent circuit model is established based on the five-level rate equations to describe their characteristics. In order to illustrate the capability of the model, the steady and dynamic performances of the fabricated THz QCLs are simulated by the model.Compared to the sophisticated numerical methods, the presented model has advantages of fast calculation and good compatibility with circuit simulation for system-level designs and optimizations. The validity of the model is verified by the experimental and numerical results.

Analysis for Transmission of Composite Structure with Graphene Using Equivalent Circuit Model

A simple analytical method is presented to analyze the transmission of electromagnetic plane waves through multilayer stacked composite two-dimensional( 2D) structures at microwave frequencies. Unlike the traditional structure,high impedance surface with graphene sheet is proposed. The structure includes graphene and thin metal patches and meshes. Simple analytical formulas are introduced for the surface impedance of graphene and for the grid impedance of electrically dense arrays of metal square patches or strips. The result of transmission properties is based on the dynamic tunable model of the high impedance surface,which considers the surface conductivity of graphene layer. The transmission coefficient obtained by using the equivalent circuit method is validated against full-wave numerical simulations. The considered equivalent circuit method can be useful in the design of graphene tunable planar devices.

Extrinsic equivalent circuit modeling of InP HEMTs based on full-wave electromagnetic simulation

With the widespread utilization of indium-phosphide-based high-electron-mobility transistors(InP HEMTs)in the millimeter-wave(mmW)band,the distributed and high-frequency parasitic coupling behavior of the device is particularly prominent.We present an InP HEMT extrinsic parasitic equivalent circuit,in which the conductance between the device electrodes and a new gate-drain mutual inductance term L_(mgd)are taken into account for the high-frequency magnetic field coupling between device electrodes.Based on the suggested parasitic equivalent circuit,through HFSS and advanced design system(ADS)co-simulation,the equivalent circuit parameters are directly extracted in the multi-step system.The HFSS simulation prediction,measurement data,and modeled frequency response are compared with each other to verify the feasibility of the extraction method and the accuracy of the equivalent circuit.The proposed model demonstrates the distributed and radio-frequency behavior of the device and solves the problem that the equivalent circuit parameters of the conventional InP HEMTs device are limited by the device model and inaccurate at high frequencies when being extracted.

An equivalent model of discharge instability in the discharge chamber of Kaufman ion thruster

The industrial application of the Kaufman ion thruster in its arc stage is limited owing to the instability of the discharge pulse.Presently,a complete prediction model that can predict the discharge pulse in the high-current stage does not exist.In this study,a complete prediction model for the pulse in the ion thruster is established using the zero-dimensional plasma discharge model and equivalent circuit model.The zero-dimensional plasma discharge model is used to obtain the corresponding plasma parameters by calculating the beam current,discharge current,voltage,and gas flow under actual working conditions.The input parameters of the equivalent circuit model are calculated using empirical formulae to acquire the estimated discharge waveforms.The pulse waveforms obtained using the model are found to be consistent with the experimental results.The model is used to evaluate the process of rapid changes in plasma density.Additionally,this model is employed to predict changes in the pulse waveforms when the volume of the discharge chamber and grid plate transmittance are changed.

Design and Verification of Equivalent Circuit for Cable Electrostatic Discharge

In the process of production, transportation and assembly, cable assemblies can get a lot of electrostatic charge by friction, dragging, pulling and induction. These residual charges can be discharged when Electrostatic sensitive device connected with it and can cause the complete failure or potential failure of the electrostatic sensitive product. In this paper, the theoretical model of cable assemblies is established by analyzing the characteristics of cable assemblies, and the equivalent RF circuit is designed. The static discharge characteristics of the cable are analyzed and verified by simulation.

Online Identification of Lithium-ion Battery Model Parameters with Initial Value Uncertainty and Measurement Noise

Online parameter identification is essential for the accuracy of the battery equivalent circuit model(ECM).The traditional recursive least squares(RLS)method is easily biased with the noise disturbances from sensors,which degrades the modeling accuracy in practice.Meanwhile,the recursive total least squares(RTLS)method can deal with the noise interferences,but the parameter slowly converges to the reference with initial value uncertainty.To alleviate the above issues,this paper proposes a co-estimation framework utilizing the advantages of RLS and RTLS for a higher parameter identification performance of the battery ECM.RLS converges quickly by updating the parameters along the gradient of the cost function.RTLS is applied to attenuate the noise effect once the parameters have converged.Both simulation and experimental results prove that the proposed method has good accuracy,a fast convergence rate,and also robustness against noise corruption.

基于惠更斯等效原理的高速高密度PCB分级建模方法

当带宽达到20 GHz以上时(波长从15 mm到无穷小),高速高密度电子系统的内部电路电磁环境变得十分复杂,越来越难以建模和分析预测,进一步当带宽达到40 GHz以上时,电路电磁环境问题将变得更加尖锐.为在设计阶段能够对电磁作用过程、作用效应进行预测评估及控制,需要精确的建模方法和针对大尺度问题的快速计算技术,尤其是超大带宽超高速混合电路和集成电路.本文提出了基于混合电路环境电磁计算基础理论的跨尺度处理技术,通过惠更斯等效原理和电磁奇异性几何结构的电磁收敛降速机理的利用,解决了多维交叉多尺度电路电磁环境场路融合的高效率高精度建模技术挑战;利用惠更斯等效原理和基尔霍夫积分方程,在区域边界面上定义了惠更斯端口,提出了对于任意复杂印制电路板(Printed Circuit Board,PCB)同时垂直方向和水平方向区域分解的一般方法,实现了任意PCB结构的分级分类处理和模块化封装,提高了高速高密度电子系统分析的灵活度;提出了基于几何结构电磁学多重本地本征展开的技术途径,发展了基于模式和区域分解分割的快速并行处理技术,通过电磁锐变区域本征描述及场分布的本征基函数表征,实现了高精度和高计算速度兼得,减少了复杂电子系统的计算时间和设计时间.统计数据表明,本文提出的方法在0~40 GHz大带宽频率范围内频偏误差为3.7%、幅度偏差为±3 dB.本文提出的PCB分级建模分析方法可以应用于高端电子通信系统设计,提升我国宽带高速数模系统的高效电路设计和环境电磁调控能力,缩短产品研发周期.

基于锂离子电池电化学机理特性的电气等值模型研究

为更准确地表征低倍率充放电工况下电池内外部的动态状况,该文根据锂离子电池电化学原理推导出一种机理电气等值模型,明确机理电气等值模型相关电气元件参数的计算方法,揭示其与锂离子电池电化学参数之间的关联。所提机理电气等值模型兼具锂离子电化学模型的精度以及常规经验等效电路模型在储能控制参数整定、大规模储能电站等效建模方面便捷性的优势,更适用于新型电力系统场景下的储能电站建模、仿真、参数整定及安全监测。

引入PID反馈的SHAEKF算法估算电池SOC

电池荷电状态(SOC)的估算精度是电动汽车电池组的重要指标。为提升SOC估算精度,在融合Sage-Husa扩展卡尔曼滤波(SHEKF)算法与自适应扩展卡尔曼滤波(AEKF)算法的基础上,增加比例积分微分(PID)反馈环节,形成改进算法。采用粒子群优化(PSO)算法对二阶RC等效电路模型进行参数辨识;用开源电池数据集对模型和算法进行实验和分析。改进的SHAEKF算法在电池动态应力测试(DST)、北京动态应力测试(BJDST)和美国联邦城市驾驶(FUDS)等工况下的平均估计误差都在1%以内,与单纯的融合算法SHAEKF算法相比,最大误差可减小5%。

基于DKF-Bi-LSTM的阀控式铅酸电池SOC在线估计方法

精准估计阀控式铅酸蓄电池的荷电状态(SOC)对变电站直流系统的可靠性和安全性有着重要的作用,为提高SOC估算精度,提出一种基于DKF-Bi-LSTM的铅酸蓄电池SOC在线估计方法,基于二级结构的双卡尔曼滤波算法,分别进行模型估计和状态估计。通过卡尔曼滤波算法对模型参数进行动态跟踪,进而基于扩展卡尔曼滤波算法在线估算电池SOC值。将在线估算结果、电流、电压、温度值作为Bi-LSTM神经网络的输入,电池SOC预测值作为网络输出,实现对电池SOC的在线估计。经测试发现,与DKF和Bi-LSTM算法相比,DKF-Bi-LSTM算法的SOC预测均方根误差更小,其SOC在线估计方法具有更高的准确性。

一种基于ISBO算法的锂离子电池等效电路模型辨识方法研究

锂离子电池等效电路模型的参数辨识方法对模型精度有较大的影响。针对缎蓝园丁鸟优化SBO(satin bowerbird optimization)算法收敛精度低和收敛速度慢的问题,提出一种改进的缎蓝园丁鸟优化ISBO(improved satin bowerbird optimization)算法。采用惯性权重、柯西变异、高斯变异和贪婪选择策略来提高ISBO算法的收敛精度,并利用标准测试函数对其收敛性能进行验证。结合电池充放电数据,将提出的ISBO算法用于锂离子电池等效电路模型的参数辨识。实验结果表明,与SBO和自适应权重粒子群优化算法相比,ISBO算法参数辨识精度较高且辨识精度不受电池工况的影响。

基于AR-ECM平均差异模型的串联电池组SOC、容量多尺度联合估计方法

考虑电池单体老化差异所致的电池组不一致性,针对串联电池组荷电状态(state of charge,SOC)、容量估计问题,提出一种基于自回归等效电路模型(autoregression equivalent circuit model,AR-ECM)的平均差异模型(mean-difference model,MDM)。基于此模型,提出串联电池组SOC、容量多尺度联合估计算法。该算法由2个部分组成,一是基于AR-ECM的MDM及差异化模型参数辨识策略:条件辨识策略和定频分组辨识策略;二是基于多时间尺度H无穷滤波(multi-timescale H infinity filter,Mts-HIF)的电池组SOC、容量联合估计算法。通过将所提出MDM中的自回归平均模型(autoregression mean model,AR-MM)与传统MDM中的n阶RC平均模型(nRC mean model,nRC-MM)比较,结果表明所提出的AR-MM在复杂运行工况下具有更优的动态跟随性能。依据最小化信息量准则(akaike information criterion,AIC),AR-MM具有更优的复杂度与精度的权衡。通过与基于多时间尺度扩展卡尔曼滤波(multi-timescale extended Kalman filter,Mts-EKF)联合状态估计算法比较,结果表明所提出的Mts-HIF状态估计算法具有更优的鲁棒性、精度和收敛速度。

利用改进SCE算法的锂离子电池参数辨识

针对传统参数辨识方法中存在的易陷入局部最优和精度低问题,提出一种改进洗牌复杂演化算法(shuffed complex evolution, SCE).首先,提出描述电池的动态特性的二阶RC等效电路模型,并根据恒流放电工况测试数据集进行锂离子电池等效模型确定待辨识参数.其次,将模型模拟端电压值与电池真实测试端电压均方根误差作为目标函数,并通过所提出的优化算法来寻找模型最优参数.最后,使用DST、 FUDS的锂离子电池动态工况数据集进行仿真验证,并与粒子群算法、灰狼算法、遗传算法进行比较.仿真结果表明,本方法在辨识精度方面具有优势,算法的参数辨识均方根误差(ERMS)平均值是0.016 6 V,相比较其他优化算法,分别降低了7.8%、 8.3%、 14.9%.

无线激光传输系统收发电路的设计与实现

针对航天发动机、涡轮机等旋转部件的温度测量系统中的信号传输问题,以850 nm波长的红外光为载体,设计了基于FPGA的无线激光通信的数据传输系统。该系统由转子端的光发射模块、定子端的光接收模块、地面可视化设备3部分组成。此外,在前置放大电路中引入一个反馈电容,系统的开环增益曲线会增加一个极点做补偿以提升系统的稳定,并进行了仿真验证。在此基础之上,搭建实验系统对电路性能进行测试。通过仿真及实验验证,结果表明:设计的方案可以实现传输速率为40 Mbit/s的稳定传输,为旋转环境的动态监测技术中的无线数据传输提供了一种可行性方案。

The initial stages of Li_(2)O_(2) formation during oxygen reduction reaction in Li-O_(2) batteries:The significance of Li_(2)O_(2) in charge-transfer reactions within devices

Lithium-oxygen batteries are a promising technology because they can greatly surpass the energy density of lithium-ion batteries.However,this theoretical characteristic has not yet been converted into a real device with high cyclability.Problems with air contamination,metallic lithium reactivity,and complex discharge and charge reactions are the main issues for this technology.A fast and reversible oxygen reduction reaction(ORR)is crucial for good performance of secondary batteries',but the partial knowledge of its mechanisms,especially when devices are concerned,hinders further development.From this perspective,the present work uses operando Raman experiments and electrochemical impedance spectroscopy(EIS)to assess the first stages of the discharge processes in porous carbon electrodes,following their changes cycle by cycle at initial operation.A growth kinetic formation of the discharge product signal(Li_(2)O_(2))was observed with operando Raman,indicating a first-order reaction and enabling an analysis by a microkinetic model.The solution mechanism in the evaluated system was ascribed for an equivalent circuit with three time constants.While the time constant for the anode interface reveals to remain relatively constant after the first discharge,its surface seemed to be more non-uniform.The model indicated that the reaction occurs at the Li_(2)O_(2) surface,decreasing the associated resistance during the initial discharge phase.Furthermore,the growth of Li_(2)O_(2) forms a hetero-phase between Li_(2)O_(2)/electrolyte,while creating a more compact and homogeneous on the Li_(2)O_(2)/cathode surface.The methodology here described thus offers a way of directly probing changes in surface chemistry evolution during cycling from a device through EIS analysis.

空心阴极羽流等离子体放电不稳定性二维仿真模型

空心阴极放电过程中空间电势振荡会影响其工作性能,振荡过程产生的高能离子会对阴极孔产生溅射腐蚀,进而严重影响空心阴极的使用寿命。建立由质点网格(Particle-in-Cell,PIC)模型、振荡幅值模型与等效电路模型组成的一体化耦合模型来计算空心阴极放电过程电势振荡特性。采用PIC模型计算不同放电电流、放电电压及气体流量下羽流等离子体放电特性,获得羽流的电势、等离子数密度、电场强度和电子温度等时均参数的空间分布。基于等离子体聚集与耗散理论,建立电势振荡幅值模型,根据计算得到的时均参数来预估空间电势振荡幅值。将等离子体时均参数以及电势幅值振荡参数作为输入参数,代入到空心阴极放电等效电路模型中,从而得到相应工况下的电势振荡波形图。通过和实验结果对比发现,所建立的一体化耦合模型能较好地预估空心阴极羽流等离子体电势振荡特性,研究成果可用于指导空心阴极稳定放电,提升空心阴极在轨工作时限。

基于等效电路模型的云端动力电池寿命估计

由于目前动力电池管理系统(battery management system,BMS)存在存储小、算力低等问题,仅依靠BMS估计出的容量误差会随电池荷电状态(state of charge,SOC)累计误差增大而逐渐增大。为实现动力电池寿命准确估计,提出了基于等效电路模型(equivalent circuit model,ECM)的动力电池容量估计方法。模型基于开路电压(open circuit voltage,OCV)和SOC的关系,直接建立1阶RC模型和容量联系;通过粒子群优化算法(particle swarm optimization,PSO)寻优最小仿真端电压与实际端电压的均方根误差(root-mean-square error,RMSE),此时辨识结果为初步估计容量,结合多项式回归(polynomial curve fitting,PCF)控制卡尔曼滤波(kalman filter,KF)对辨识结果进行了优化。最后对云端实车与传统方法测得的容量进行对比验证,二者的RMSE小于3%且最大绝对误差小于2 Ah。与现有方法相比,该方法能够不单依赖BMS数据准确估计容量。同时,对于实车等复杂场景的应用做出了优化,可以实现实车场景下的容量精确估计。

基于电化学阻抗谱的锂离子电池分级安全预警方法

电化学阻抗谱(EIS)是一种无创原位检测和无损检测方法,可以反映电池内部不同结构的状态。基于EIS的指标可以作为故障预警的重要和优良指标,解决不及时和误报的问题。根据不同过充阶段的EIS特点,分阶段建立了与之对应的分数阶模型。用固态电解质相间膜电阻(R_(SEI))和电荷转移电阻(R_(ct))来表示中频段两个电弧随过充的变化。基于与电池内部结构损伤相关的R_(SEI)和R_(ct)指标,提出了三级预警方法。同时采用了新电池和循环老化过的软包电池进行了不同倍率的过充实验,验证了该方法的可靠性。

混合励磁式电涡流制退机电磁场与阻力特性分析

电涡流制退机具有无液体泄漏、无需密封、阻力稳定的优势。与目前应用较多的永磁式电涡流制退机相比,混合励磁式电涡流制退机采用线圈替代了一部分永磁体,对阻力特性的调节效果更好。对比了混合励磁式电涡流制退机2种可能的结构形式,然后根据磁路分析与初步计算选择出具有更好阻力性能的结构。针对该结构,利用等效磁路法计算气隙磁场,采用子域模型考虑感生涡流影响,建立了求解混合励磁式电涡流制退机阻力值的等效子域模型。根据某口径火炮反后坐要求,确定了制退机的主要尺寸参数,完成了混合励磁式电涡流制退机结构参数的前期设计,并通过数值计算对解析计算结果进行了验证。接着,针对某口径火炮发射时的工况建立仿真模型,以炮膛合力曲线和复进机力的后坐行程函数曲线作为条件输入,分析强冲击载荷下混合励磁式电涡流制退机的电磁阻尼力、后坐位移和后坐速度规律。最后,分析了不同气隙宽度与内筒的电导率对电磁阻尼力的影响,结果表明气隙宽度越小电磁阻尼力越大,同时过大的内筒电导率会导致电磁阻尼力呈现“马鞍”型。本文研究可为混合励磁式电涡流制退机的工程化应用提供理论基础。

基于无迹卡尔曼滤波的动力电池状态估计

准确预测动力电池的荷电状态(SOC)与健康状态(SOH)对电动汽车电池系统的安全运行至关重要。卡尔曼滤波(KF)算法被广泛用于动力电池的状态估计,但非线性误差较大。提出利用无迹卡尔曼滤波(UKF)算法实现对动力电池状态的准确估计。首先,通过分析动力电池实验数据,建立一阶等效电路模型,模型拟合优度达到0.992。随后,加入容量衰退机制模拟锂离子电池老化过程,并对电池进行恒流充电以及随机放电循环,模拟动力电池实际工况。不同初始值下,SOC、SOH估计的均方根误差均小于0.01,且随着循环次数的增加,误差逐渐减小。