Fault Estimation for a Class of Markov Jump Piecewise-Affine Systems: Current Feedback Based Iterative Learning Approach

In this paper, the issues of stochastic stability analysis and fault estimation are investigated for a class of continuoustime Markov jump piecewise-affine(PWA) systems against actuator and sensor faults. Firstly, a novel mode-dependent PWA iterative learning observer with current feedback is designed to estimate the system states and faults, simultaneously, which contains both the previous iteration information and the current feedback mechanism. The auxiliary feedback channel optimizes the response speed of the observer, therefore the estimation error would converge to zero rapidly. Then, sufficient conditions for stochastic stability with guaranteed performance are demonstrated for the estimation error system, and the equivalence relations between the system information and the estimated information can be established via iterative accumulating representation.Finally, two illustrative examples containing a class of tunnel diode circuit systems are presented to fully demonstrate the effectiveness and superiority of the proposed iterative learning observer with current feedback.

Instantaneous Current Feedback Control Strategy on Buck Mode Inverter

Buck型逆变器的电感电流瞬时值反馈控制和电容电流瞬时值反馈控制存在本质区别。以差动正激直流斩波器型高频环节逆变器为例，采用理论推导方法，研究这两种电流控制逆变器的稳定性、输出外特性、短路能力、输出功率特性、带非线性负载能力及动态响应特性。研究结果表明，电感电流瞬时值反馈控制逆变器具有电感电流和输出功率受限、较强的过载和短路能力、较软的输出外特性、较弱的带非线性负载能力、较差的动态响应等特点；而电容电流瞬时值反馈控制逆变器具有电感电流和输出功率不受限、较弱的过载能力、无短路能力、硬的输出外特性、较强的带非线性负载能力、较好的动态响应等特点。研究成果为Buck型逆变器电流型控制策略的选择及其设计提供重要的理论依据。

Voltage/Current-Mode Multifunction Filters Using One Current Feedback Amplifier and Grounded Capacitors

One configuration for realizing voltage-mode multifunction filters and another configuration for realizing current-mode multifunction filters using current feedback amplifiers (CFAs) are presented. The proposed voltage-mode circuit exhibit simultaneously lowpass and bandpass filters. The proposed current-mode circuit exhibit simultaneously lowpass, bandpass and highpass filters. The proposed circuits offer the following features: no requirements for component matching conditions;low active and passive sensitivities;employing only grounded capacitors and the ability to obtain multifunction filters from the same circuit configuration.

Inductor Current Sampled Feedback Control of Chaos in Current-Mode Boost Converter

A chaos control strategy for chaotic current-mode boost converter is presented by using inductor current sampled feedback control technique.The quantitative analysis of control mechanism is performed by establishing a discrete alterative map of the controlled system.The stability criterion,feedback gain,and corresponding critical duty ratio are obtained from the eigenvalue of the map.The simulation results verify the t heoretical analysis results of the control strategy.

A Grounded Capacitor Differentiator Using Current Feedback Amplifier

A new non-inverting RC active differentiator network base on a current feedback amplifier and using a grounded capacitor is described. Small time constant can be achieved by adjusting a single grounded resistor. Because the output impedance of the CFA is very low, the output terminal of the proposed circuit can be directly connected to the next stage. Experimental results that confirm theoretical analysis are presented.

Two Simple Analog Multiplier Based Linear VCOs Using a Single Current Feedback Op-Amp

Two simple voltage-controlled-oscillators (VCO) with linear tuning laws employing only a single current feedback operational amplifier (CFOA) in conjunction with two analog multipliers (AM) have been highlighted. The workability of the presented VCOs has been demonstrated by experimental results based upon AD844 type CFOAs and AD534 type AMs.

Feedback Control of Plasma Current and Horizontal Position in HT-7

There is a strong magnetic coupling between poloidal field coils of superconducting tokamak HT-7, especially between ohinic heating and vertical field coils. These coils are connected to individual power supply. The control system for the plasma current and horizontal position control has been designed and showed satisfactory results with the feedback control of multivari- able feedforward-decoupling and var-parameter PID controller to simultaneously modulate power supplies. The design and analysls of the control system is presented.

Development of Surface Grating Distributed Feedback Quantum Cascade Laser for High Output Power and Low Threshold Current Density

We report on the room-temperature cascade laser （QCL） at λ -4.7μm. cw operation of a surface grating Both grating design and material distributed feedback （DFB） quantum optimization are used to decrease the threshold current density and to increase the output power. For a high-reflectivity-coated 13-μm-wide and 4- mm-long laser, high wall-plug efficiency of 6% is obtained at 20℃ from a single facet producing over I W of ew output power. The threshold current density of DFB QCL is as low as 1.13kA/cm^2 at 10℃ and 1.34kA/cm2 at 30℃ in cw mode. Stable single-mode emission with a side-mode suppression ratio of about 30 dB is observed in tile working temperature range of 20-50℃.

Upgrading Tests Using PSIM Tool of MPPT-PV Feedback-Current Controller

This paper presents improvement tests based in a feedback-current controller designed to Tracking Maximum Power Point in photovoltaic system (MPPT-PV). Previously, a version was developed exhibiting results satisfactory in simulation and through of a low cost prototype. Now, using a sophisticated physical model of solar cell available in PSIM program is shown other cases, considering variations both irradiation and temperature to evaluate successfully the controller. The results show that its system is suitable under dynamical changing atmospheric conditions operating with effectiveness acceptable.

某型地面发控点火电流异常分析和电路改进

针对某型地面发控系统在使用过程中出现的点火电流异常问题,采用数学方法研究点火电流与元器件参数的变化规律,发现地面发控点火电流在某些环境下不稳定的根本原因。最后提出一种闭环控制方案,增加电流反馈环节,解决点火电流异常问题。实际应用验证表明,改进后的点火电路能适应更大的点火负载,有效提高了点火的可靠性。

红外探测器中一种电容式反馈跨阻放大器的设计

放大器电路对提高红外成像技术中红外探测器的读出精度,是至关重要的。针对电容式反馈跨阻放大器的设计进行了研究,提出了一种在反馈回路中用晶体管代替反馈电阻的新的拓扑结构。对于所提出的拓扑结构,提出并分析了与系统稳定性相关的诸如截止频率和衰减比等的总体频率响应和设计参数,从而获得高直流输入动态范围。此外,还讨论了在直流反馈回路中加入额外的电容以确保系统的稳定性。分析、仿真和实验结果的良好一致性验证了所提出的CF-TIA方案的有效性,而且所提出的电路设计在正常或低直流输入下的整体噪声性能方面相比于传统的CF-TIA方案更具优势。尽管本文中的电路采用分立元件实现,但提出的频率响应模型和稳定性分析适用于所有CF-TIA应用和CMOS芯片设计。

弱电网下LCL型并网逆变器高鲁棒性并网电流反馈有源阻尼策略

并网电流反馈有源阻尼(grid-current-feedback-active-damping,GCFAD)策略可以在不增加额外传感器的前提下,有效抑制LCL型并网逆变器的谐振尖峰。在电网电压畸变的工况下,GCFAD策略往往与电网电压前馈策略同时使用以改善并网电流质量。然而,通过研究发现,传统GCFAD策略等效虚拟阻抗在中低频段的正阻特性会导致并网逆变器输出阻抗在中频段产生一定的相位滞后,从而降低了系统在电网电压畸变且附加电网电压前馈策略的情况下,对电网阻抗变化的鲁棒性。为了解决这一问题,提出了一种高鲁棒性并网电流反馈有源阻尼(high robustness grid-current-feedback-active-damping,HR-GCFAD)策略,使虚拟阻抗在高频处呈现正阻特性以抑制LCL谐振尖峰,增强了系统的稳定性;在中低频段呈现负阻特性以提高系统中频段输出阻抗相位,进而提高了系统在附加电网电压前馈策略时对电网阻抗变化的鲁棒性。理论分析和实验结果充分验证了所提策略的有效性。

一种带有尾电流源反馈的FBAR振荡器

为改善振荡器相位噪声性能,设计了一种带有尾电流源反馈的薄膜体声波谐振器(FBAR)振荡器。研究表明,尾电流源晶体管闪烁噪声和谐振回路是振荡器相位噪声的主要来源。为了降低尾电流源晶体管闪烁噪声对振荡器相位噪声的影响,采用两组对称分离且工作在亚阈值区域的P型金属氧化物半导体(PMOS)偏置电流源进行尾电流反馈。与传统单个尾电流源相比,该技术具有更好的相位噪声性能。同时,基于对Hajimiri噪声模型的分析,利用尾电流源反馈技术,控制振荡器在振幅达到峰值及零穿越点时的电流大小,以进一步改善相位噪声性能。高Q值谐振器可以显著提高振荡器的整体相位噪声性能,因此,设计采用高Q值微机电系统(MEMS)器件FBAR作为谐振腔,并通过TSMC 180 nm RF CMOS工艺完成电路设计。结果表明:该振荡器输出频率为1.93 GHz,整体电路功耗为580μW,在1 kHz偏频处相位噪声为-89.7 dBc/Hz,计算得到灵敏值(Factor Of Merit,FOM)为217 dB。

图腾柱功率因数校正器的二自由度控制分析

TPFC一般采用一自由度输出电压控制,在负载变化时输出电压动态特性较差,且启动过程存在明显超调。本文在推导TPFC双闭环控制结构基础上,引用了负载电流前馈控制和输出电压反馈补偿控制,构成两种二自由度(2DOF)控制结构。仿真分析表明,负载电流前馈型2DOF控制可以有效抑制负载变化引起的输出电压波动,但启动过程超调明显;输出电压反馈补偿型2DOF控制可以实现输出电压无超调启动,但是抑制负载变化的能力较差;综合负载电流前馈型和输出电压反馈补偿型的2DOF控制获得满意的输出电压控制效果,表现为启动过程无超调和变载过程无波动。

混合级联直流输电系统整流/逆变不同控制回路动态交互作用与稳定性研究

为了研究混合级联直流输电系统整流侧和逆变侧各换流器控制系统间的交互作用,文中首先建立混合级联直流输电系统的状态空间模型,并推导得到系统的多输入多输出传递函数模型。然后针对不同的研究目标,根据单通道分析设计理论建立等效单输入单输出反馈控制模型;在此基础上,分离出不同控制回路的耦合控制通道,定量评估系统强度、逆变侧交流联络线与控制参数等对控制回路间交互作用的影响。理论分析表明,当整流侧或逆变侧交流系统强度降低时,两侧控制回路间交互作用增强;当交流联络线长度缩短时,逆变侧电网换相换流器(line commutated converter,LCC)和模块化多电平变换器(multilevel modular converter,MMC)控制回路间的动态交互增强,各控制环节参数之间存在相互制约关系。最后,在PSCAD/EMTDC上搭建混合级联直流输电系统的电磁暂态详细仿真模型,验证所建立单输入单输出反馈控制模型及上述理论分析结果的正确性。

多挡位电流比较仪研究

针对传统的电流比较仪均采用人工操作,自动化程度和检测效率低的问题,设计了多挡位电流比较仪。采用嵌入式单片机控制技术,智能化测量检测绕组信号,自动输出测试数据,实现了自主跟随,负反馈智能控制,提高了工作效率及测试精度。

LCL型并网逆变器电网电压前馈控制策略研究

为抑制LCL型并网逆变器系统固有谐振频率,消除非线性负载带来的电网电压畸变并网电流谐波,通过电容电流反馈有源阻尼控制减小LCL固有谐振。为抑制电网电压对并网电流产生的影响,采用电网电压前馈控制策略实现,对比各种前馈控制效果,从而得到高质量的并网电流。通过MATLAB/Simulink仿真验证所提前馈控制策略有效。

Roles of Equatorial Ocean Currents in Sustaining the Indian Ocean Dipole Peak

In this study,on the basis of the results of the European Centre for Medium-Range Weather Forecasts Ocean Reanalysis System 4,the response of equatorial ocean currents and their roles during the peak phase of the Indian Ocean Dipole(IOD)are comprehensively explored.During the IOD peak season,a series of ocean responses emerge.First,significant meridional divergence in the surface layer and convergence in the subsurface layer are found in the equatorial region.The equatorial easterly winds and offequatorial wind curl anomalies are found to be responsible for the divergence at 55°–80°E and the convergence at 70°–90°E.Second,the meridional divergence and convergence are found to favor a weakened Wyrtki jet(WJ)in the surface layer and an enhanced Equatorial Undercurrent(EUC)in the subsurface layer,respectively.Therefore,these ocean responses provide ocean positive feedback that sustains the IOD peak as the weakened WJ and enhanced EUC help maintain the zonal temperature gradient.Additionally,heat budget analyses indicate that the weakened WJ favors sea surface temperature anomaly warming in the western Indian Ocean,whereas the enhanced EUC maintains the sea surface temperature anomaly cooling in the eastern Indian Ocean.

Controlling Beam Halo-Chaos via Time-Delayed Feedback

The study of controlling high-current proton beam halo-chaos has become a key concerned issue for manyimportant applications. In this paper, time-delayed feedback control method is proposed for beam halo-chaos. Particle incell simulation results show that the method is very effective and has some advantages for high-current beam experimentsand engineering.

Control of Halo-Chaos in Beam Transport Network via Neural Network Adaptation with Time-Delayed Feedback

在横梁运输网络(隧道) 的光圈混乱控制的题目为高水流的质子横梁 since1990' 的许多重要应用程序成为了一个关键担心的问题。在这篇论文，磁场适应控制基于神经网络，推迟 withtime 的反馈为与周期的集中的隧道在横梁运输网络压制横梁光圈混乱被建议。高水流的质子横梁的信封半径被控制由合适选择控制结构和神经网络的参数到达匹配的横梁半径，调整延期时间和神经网络的控制系数。