Performance enhancement of a viscoelastic bistable energy harvester using time-delayed feedback control

This paper focuses on the stochastic analysis of a viscoelastic bistable energy harvesting system under colored noise and harmonic excitation, and adopts the time-delayed feedback control to improve its harvesting efficiency. Firstly, to obtain the dimensionless governing equation of the system, the original bistable system is approximated as a system without viscoelastic term by using the stochastic averaging method of energy envelope, and then is further decoupled to derive an equivalent system. The credibility of the proposed method is validated by contrasting the consistency between the numerical and the analytical results of the equivalent system under different noise conditions. The influence of system parameters on average output power is analyzed, and the control effect of the time-delayed feedback control on system performance is compared. The output performance of the system is improved with the occurrence of stochastic resonance(SR). Therefore, the signal-to-noise ratio expression for measuring SR is derived, and the dependence of its SR behavior on different parameters is explored.

四极电子式RCD用于单相负荷的缺陷探讨

研究了四极电子式RCD用于单相负荷理论上的可行性。运用实例和理论分析,证明了单相负荷不平衡并不影响四极电子式RCD的动作特性。运用实例分析了单相负荷接地故障受自然泄漏电流干扰的情况,得知导致四极电子式RCD误动作的原因是自然泄漏电流。提出四极RCD接单相负荷易出现“断零”事故,并提出采用“3P+N”极RCD可避免此种事故。

Rambus通过第四代DDR5 RCD提升数据中心服务器性能

近日Rambus宣布推出先进的第四代DDR5寄存时钟驱动器(RCD),并于2023年第四季度开始向主要DDR5内存模块(RDIMM)制造商提供样品。Rambus第四代RCD将数据传输速率提高到7200 MT/s,设立了新的性能标杆,相比目前的4800 MT/s DDR5模块解决方案,其内存带宽提高了50%。

电梯的RCD浅析

本文根据电梯漏电保护装置的工作原理,分析了电梯主回路设置RCD易发故障的原因。为了降低电梯因RCD而产生的故障率,建议电梯主回路尽量避免使用RCD。若需要使用RCD或其他漏电保护型开关,建议使用延时动作的漏电保护开关,以避免电梯启动时的误动作;同时建议除电梯主回路之外,其他与乘客或维保人员直接可接触的控制电路及插座,装设RCD的额定动作电流不大于30mA。

浅谈低压供配电系统设计中断路器和RCD自动切断电源的防护措施

电气装置电击是电气安全的最大威胁之一,如果电气设备、电缆等出现故障,人们接触到带电设备时可能会发生电击事故,可能导致人身危险甚至死亡,也会产生高温,引燃周围可燃物品,可能导致火灾,损害社会和人民的财产安全和人身安全。因此,在低压供配电系统设计中,选择正确的电气设备至关重要,以减少电气装置电击带来的风险。电气装置电击中接地故障又是出现最多、涉及人身安全最多的重要课题,尤其是应用最广泛的自动切断电源的防护措施,因此必须对该种故障防护给予特别的重视。

Effects of time-delayed vibration absorber on bandwidth of beam for low broadband vibration suppression

The effects of time-delayed vibration absorber(TDVA) on the dynamic characteristics of a flexible beam are investigated. First, the vibration suppression effect of a single TDVA on a continuous beam is studied. The first optimization criterion is given,and the results show that the introduction of time-delayed feedback control(TDFC) is beneficial to improving the vibration suppression at the anti-resonance band. When a single TDVA is used, the anti-resonance is located at a specific frequency by the optimum design of TDFC parameters. Then, in order to obtain low-frequency and broad bands for vibration suppression, multiple TDVAs are uniformly distributed on a continuous beam,and the relationship between the dynamic responses and the TDFC parameters is investigated. The obtained relationship shows that the TDVA has a significant regulatory effect on the vibration behavior of the continuous beam. The effects of the number of TDVAs and the nonlinearity on the bandgap variation are discussed. As the multiple TDVAs are applied, according to the different requirements on the location and bandwidth of the effective vibration suppression band, the optimization criteria for the TDFC parameters are given, which provides guidance for the applications of TDVAs in practical projects such as bridge and aerospace.

Design and analysis of active disturbance rejection control for time-delay systems using frequency-sweeping

For the typical first-order systems with time-delay,this paper explors the control capability of linear active disturbance rejection control(LADRC).Firstly,the critical time-delay of LADRC is analyzed using the frequency-sweeping method and the Routh criterion,and the stable time-delay interval starting from zero is accurately obtained,which reveals the limitations of general LADRC on large time-delay.Then in view of the large time-delay,an LADRC controller is developed and verified to be effective,along with the robustness analysis.Finally,numerical simulations show the accuracy of critical time-delay,and demonstrate the effectiveness and robustness of the proposed controller compared with other modified LADRCs.

Group Hybrid Coordination Control of Multi-Agent Systems With Time-Delays and Additive Noises

A new kind of group coordination control problemgroup hybrid coordination control is investigated in this paper.The group hybrid coordination control means that in a whole multi-agent system(MAS)that consists of two subgroups with communications between them,agents in the two subgroups achieve consensus and containment,respectively.For MASs with both time-delays and additive noises,two group control protocols are proposed to solve this problem for the containment-oriented case and consensus-oriented case,respectively.By developing a new analysis idea,some sufficient conditions and necessary conditions related to the communication intensity betw een the two subgroups are obtained for the following two types of group hybrid coordination behavior:1)Agents in one subgroup and in another subgroup achieve weak consensus and containment,respectively;2)Agents in one subgroup and in another subgroup achieve strong consensus and containment,respectively.It is revealed that the decay of the communication impact betw een the two subgroups is necessary for the consensus-oriented case.Finally,the validity of the group control results is verified by several simulation examples.

关于A电厂大功率低压电机RCD装置换型改造的经验总结

大功率低压电动机(200kW及以上电机)一般用在发电厂的给水、疏水相关回路中,这些低压电动机起动电流高达上千安培。在供配电环节,配套的开关容量通常很大,此外,在电机保护配置上,除了常见的过流速断、过载长延时之外,为保护电缆在发生单相接地故障时能承受热稳定冲击,还会单独配备零序保护甚至是RCD(剩余电流保护装置)。由于RCD可调定值小,配套的CT二次侧输出是mV/mA级信号,易受现场其他设备产生的电磁干扰,因此对安装要求极高。文章主要对A发电厂400kW以上大型电动机配备的RCD装置换型改造过程中遇到的问题进行分析和处理,归纳和总结改造相关经验,以期为业内人员提供参考。

Effects of Physical Parameters and Time-Delay Coefficients on the Amplitude and Frequency Bandwidth of Saturation Controller for a Beam Vibration

In this paper, the influence of physical parameters on the width of saturated control frequency band and the influence of time delay parameters on the stability of saturated control system are studied. The analytical solution of the motion equation of the system when the main resonance and the 1:2 internal resonance occur simultaneously is obtained by multiple scale method, experimentally measured natural frequencies of nonlinear beams. The effects of excitation amplitude, delay feedback coefficients and nonlinear coefficients on saturation control are investigated. The results of the study show that the bandwidth of the saturation control can be increased by increasing the value of the external excitation, the nonlinear coefficients enhance the nonlinear phenomena of the system.

RCD钳位反激变换器的回馈能耗分析及设计考虑

对RCD钳位反激变换器的能量传输过程进行深入分析,指出为避免反馈电压Uf在整个开关管关断期间向RCD钳位电路提供能量而增大能耗,钳位电容电压UC必须大于Uf;推导得出反馈电压产生的回馈能量Wf的解析表达式,并指出Wf随着UC的增加而减小,且RCD钳位电路的总能耗等于Wf与变压器漏感储能Wlk之和。令Wlk与Wf相等,得出钳位电容的临界钳位电压UCK=2.6 Uf,并指出当UC大于UCK时,回馈电压产生的能量将小于Wlk,并以此作为确定钳位电容电压UC的依据,得出RCD钳位电路元件参数的设计方法。给出实例,通过仿真和实验结果,验证了理论分析的正确性和设计方法的可行性。

反激变换器中RCD箝位电路的分析与设计

着重考虑现有文献中被忽略的因素,如箝位二极管正、反向恢复特性和副边漏感Ls对RCD参数设计的影响等,分析了二极管的正向恢复对开关管电压尖峰的影响、反向恢复对RCD箝位电路损耗和参数设计的影响,揭示出副边漏感与原边漏感一样会增加RCD箝位电路吸收的能量,并进行了量化分析。综合考虑了二极管正向恢复特性、反向恢复特性以及副边漏感对RCD箝位电路的影响,在现有RCD参数设计方法的基础上,提出了修正后的RCD参数设计方法。仿真和实验结果验证了理论分析的正确性和设计方法的可行性。

基于光伏充电的低压混合式断路器设计及仿真

直流断路器是实现直流系统电流故障清除和隔离的关键设备。基于人工过零点的直流断路器熄弧时刻具有不确定性,且换流电容需要更换辅助电源,降低断路器可靠性,增加维护成本。为此,在传统直流断路器基础上,提出了一种基于光伏充电的混合式直流断路器拓扑结构设计方案。该方案在断路器过零点未熄弧时闭锁IGBT开关,加速电弧熄灭,并设计光伏储能供电系统为换流电容预充电能,以保障断路器持续运行。同时对所提断路器的拓扑结构、开断时序、拓扑参数进行了设计,基于MATLAB/Simulink实验平台建立了150 V混合式直流断路器模型,讨论IGBT开关器件闭锁时刻及电阻电容二极管(resistance-capacitance diode,RCD)缓冲电路对断路器开断的影响。在此基础上,通过仿真实验分析了正常和短路工况下断路器开断过程,验证了所提方案的可行性。

IGBT串联器件门极RCD有源均压电路

研究了一种门极RCD有源均压电路,用于解决IGBT串联组件中各个器件集射极电压动态分配不均衡的问题。介绍了门极RCD有源均压电路的工作原理和参数选择原则,利用IGBT不同开关状态下的等效电路分析了各个均压元件的作用,提出了满足均压技术指标要求条件下门极RCD有源均压电路参数的计算方法,建立了IGBT串联均压实验系统。实验结果表明,采用本文提出的均压电路参数设计方法,门极RCD有源均压电路在门极驱动信号同步或延时情况下均具有较好的均压效果。

用于IGBT串联的RCD均压电路参数选择

为了选择更合适的基于电阻、电容和二极管的均压电路(RCD均压电路)的元件参数,在详细分析RCD均压电路工作原理的基础上,提出了一种基于稳态的电路元件参数选择依据,并针对RCD均压电路工作过程中的几个重要时间常数进行分析。将采用该依据设计的RCD均压电路用在基于IGBT串联的直流斩波电路平台上进行了验证,实验结果表明采用该依据设计的RCD均压电路可以有效地抑制串联IGBT的动、静态不均压现象。因此,提出的依据为RCD均压电路元件的参数设计提供了理论基础和整定方向。

双RCD箝位的双管正激变换器研究

针对传统单管和双管DC-DC变换电路分别存在的高开关应力与低占空比的不足,提出一种双RCD箝位的双管正激变换电路,并对该电路进行了稳态分析及仿真与样机试验验证。结果表明,该电路不仅可将最大可调占空比由普通双管时的0.5提升至0.8左右,而且能使最大开关应力较单管有大幅下降,同时,系统具有开关应力低和可调占空比高的优点。

反激逆变器RCD钳位电路的设计与研究

反激逆变器的变压器的原边漏感对电路性能及其功率器件的安全工作影响很大,严重时会烧毁器件.针对以上问题,在变压器的原边并联RCD钳位电路,用于抑制因漏感而产生的电压尖峰,保证功率开关管的正常工作及电路的高效运行.通过仿真比较,结果证明电路设计可行.

Modeling of temperature-humidity for wood drying based on time-delay neural network

The temperature-humidity models of wood drying were developed based on Time-delay neural network and the identification structures of Time-delay neural network were given. The controlling model and the schedule model, which revealed the relation between controlling signal and temperature-humidity and the relation between wood moisture content and temperature-humidity of wood drying, were separately presented. The models were simulated by using the measured data of the experimental drying kiln. The numerical simulation results showed that the modeling method was feasible, and the models were effective.

RCD箝位反激变换器的设计与实现

论述了峰值电流控制RCD箝位反激变换器的原理,介绍了UC3843电流控制型脉宽调制器的各种设置,由UC3843构成的逆变器辅助开关电源,具有电路简单、易于多路输出、过载与短路能力强。

Distributed Platooning Control of Automated Vehicles Subject to Replay Attacks Based on Proportional Integral Observers

Secure platooning control plays an important role in enhancing the cooperative driving safety of automated vehicles subject to various security vulnerabilities.This paper focuses on the distributed secure control issue of automated vehicles affected by replay attacks.A proportional-integral-observer(PIO)with predetermined forgetting parameters is first constructed to acquire the dynamical information of vehicles.Then,a time-varying parameter and two positive scalars are employed to describe the temporal behavior of replay attacks.In light of such a scheme and the common properties of Laplace matrices,the closed-loop system with PIO-based controllers is transformed into a switched and time-delayed one.Furthermore,some sufficient conditions are derived to achieve the desired platooning performance by the view of the Lyapunov stability theory.The controller gains are analytically determined by resorting to the solution of certain matrix inequalities only dependent on maximum and minimum eigenvalues of communication topologies.Finally,a simulation example is provided to illustrate the effectiveness of the proposed control strategy.