Theoretical study of mutual control mechanism between magnetization and polarization in multiferroic materials

The mutual control mechanism between magnetization and polarization in multiferroic materials is studied. The system contains a ferromagnetic sublattice and a ferroelectric sublattice. To describe the magneto–electric coupling, we propose a linear coupling Hamiltonian between ferromagnetism and ferroelectricity without microscopic derivation. This coupling enables one to retrieve the hysteresis loops measured experimentally. The thermodynamic properties of the system are calculated, such as the temperature dependences of the magnetization, polarization, internal energy and free energy.The ferromagnetic and ferroelectric hysteresis loops driven by either a magnetic or an electric field are calculated, and the magnetic spin and pseudo-spin are always flipped synchronously under the external magnetic and electric field. Our theoretical results are in agreement with the experiments.

The Hybrid Bidirectional DC/DC Converter:Mutual Control and Stability Analysis

A hybrid bidirectional DC/DC converter(BDC)is proposed as the fundamental DC/DC module in solid-state transformers,which combines a bidirectional LLC converter and a dual-active-bridge(DAB)converter.Integrated with a mutual control scheme,both parts of this hybrid BDC can be unified into an interdependent community.In this hybrid BDC,the LLC converter supports the output voltage and improves stability by working at the resonant frequency mode and the DAB converter enhances the BDC power capability by controlling the LLC output current constant.The BDC can achieve the full-load-range soft switching of all active switches by designing the auxiliary inductor of LLC and the minimum output current of DAB.By comparing to the single DAB,the proposed BDC has the higher phase and gain margin which means the BDC improved the relative stability based on Nyquist criterion.To solve the bidirectional power control problem,a dead-band voltage control logic is adopted which can determine the BDC’s power direction based on the output voltage change.A 200 V experimental system has verified the aforementioned features and functions of the BDC.

Adaptive Power Control for mutual Interference Avoidance in Industrial Internet-of-Things

With the vigorous development of the Internet of Things and 5G technology, such as machine-to-machine and device-todevice, all kinds of data transmission including environmental monitoring and equipment control strengthens the key role of wireless sensor networks in the large-scale wireless communication system. However, especially in the complex industrial wireless applications, the low utilization efficiency of the limited wireless radio resource enhances the coexistence problem between heterogeneous networks. In this paper, from the severe mutual interference point of view, a mathematical model regarding cumulative interferences in the industrial wireless sensor networks is described. Then, from the perspective of mutual interference avoidance, an adaptive power control scheme is proposed in order to handle the normal communication needs on both the primary link and the secondary link. At last, nonlinear programming is taken to solve the corresponding optimization problem. Some typical analyses are given to verify the effectiveness of the proposed scheme on optimizing the tradeoff between the system throughput and energy consumption. Especially, the energy-efficiency of the novel scheme for Industrial Internet of Things is also analysed. Results show that the proposed power control is efficient. The throughput could be enhanced and the energy consumption could be reduced with the guarantee of mutual interference avoidance.

ANALYSIS OF THE MUTUAL INFORMATION BETWEEN INPUT AND OUTPUT OF A CLASS OF CLOCK-CONTROLLED SEQUENCES

In this paper, the mutual information between clock-controlled input and output sequences is discussed. It is proved that the mutual information is a strictly monotone increasing function of the length of output sequence, and its divergent rate is gaven.

Synchronizing Hyperchaos by Mutual Coupling Control

Coupled oscillators are common in many scientific areas,such as optics,communications,engi-neering,biology,etc.The synchronization of oscillators has important practical applications.This letter focuses on synchronization of coupled hyperchaotic oscillators,which exists in natureand in laboratory and is very important.

Static and adaptive feedback control for synchronization of different chaotic oscillators with mutually Lipschitz nonlinearities

This paper addresses the control law design for synchronization of two different chaotic oscillators with mutually Lipschitz nonlinearities. For analysis of the properties of two different nonlinearities, an advanced mutually Lipschitz condition is proposed. This mutually Lipschitz condition is more general than the traditional Lipschitz condition. Unlike the latter, it can be used for the design of a feedback controller for synchronization of chaotic oscillators of different dynamics. It is shown that any two different Lipschitz nonlinearities always satisfy the mutually Lipschitz condition. Applying the mutually Lipschitz condition, a quadratic Lyapunov function and uniformly ultimately bounded stability, easily designable and implementable robust control strategies utilizing algebraic Riccati equation and linear matrix inequalities, are derived for synchronization of two distinct chaotic oscillators. Furthermore, a novel adaptive control scheme for mutually Lipschitz chaotic systems is established by addressing the issue of adaptive cancellation of unknown mismatch between the dynamics of different chaotic systems. The proposed control technique is numerically tested for synchronization of two different chaotic Chua＇s circuits and for obtaining identical behavior between the modified Chua＇s circuit and the R6ssler system.

基于能量管理的直流微电网集群协同控制策略

为实现微电网间的协调控制及功率互济,提高能量使用效率,提出了基于能量管理的直流微电网集群协同控制策略。其采用分层式控制结构,下层为功率-电压下垂控制,中层为分布式一致性电压控制,上层为集中式控制协调各个微电网的控制策略。多层协同的控制策略使得集群中各微电网既可以独立运行又可以相互间提供功率支撑,还可以与主电网进行互联,参与电力市场,利用不同地点的资源,最大化能量利用效率,保证整个集群电压质量。在微电网间通信故障或线路断开情况下所提控制策略基本不受影响,具有一定的鲁棒性。在MATLAB/Simulink中模拟多种工况对所提控制策略进行仿真,结果表明所提控制在保证集群电压水平的同时,可以实现整个微电网集群的能量管理。

特种设备质量安全与风险防控数据共融共识与可信传递技术研究

质量安全与风险防控是保障特种设备安全运行的重要技术手段,数据的共融共识与可信传递是其重要基础。针对特种设备质控数据来源不可靠、标准不统一等问题,以电梯、大型游乐设施和长管拖车三类典型特种设备为对象,通过全链条多主体数字证书和报告的生成规则、共识机制、智能合约的研究,搭建特种设备质量安全与风险防控联盟区块链。成果将为数据和知识的上链共享奠定基础,实现数据的共融共识与可信传递,为质量安全与风险防控提供新模式。

Two Different Role Division Control Strategies for Torque and Axial Force of Conical Bearingless Switched Reluctance Motor

Although the five-degree-of-freedom magnetic levitation system composed of two conical bearingless switched reluctance motors(CBSRMs)owns the simplest structure,the torque and levitation forces are coupled greatly.Therefore,it is difficult to make the rotor rotate and be fully levitated simultaneously.To solve this problem,two different role division control strategies are proposed in this paper,i.e.individual role division and mutual role division control strategies.The difference between them is the selection of motor which controls the torque or the axial force.In order to understand the characteristics of control variables,the principle and mathematical model of CBSRM are introduced.After that,two control strategies are explained in detail.To verify the demonstrated performance,the simulations are completed with MATLAB/Simulink.

基于三有源桥串并联潮流控制器的双极直流配电网主动限流策略

直流潮流控制器是解决环网式直流配电网的线路潮流不完全可控的有效技术手段。然而,现有方法未能充分发掘其在故障限流中的潜力。该文建立了三有源桥串并联潮流控制器(triple active bridge power flow controller,TAB-PFC)的故障模量分析模型,提出一种基于TAB-PFC的双极直流配电网主动限流策略。首先阐述了TAB-PFC的限流原理,提出基于TAB-PFC的主动限流控制策略。然后对TAB-PFC不同故障阶段进行建模,并计及极间互感构建含TAB-PFC的双极直流配电网故障模量等效模型。在此基础上,分析不同参数对TAB-PFC的限流能力的影响,为其参数选取提供依据。在MATLAB/Simulink搭建了含TAB-PFC的双极直流配电网模型,验证了所提主动限流策略的有效性及故障等效电路模型和参数分析的正确性。

Adaptive Isochronal Synchronization in Mutually Coupled Chaotic Systems

This paper studies the problem of isochronal synchronization of chaotic systems with time-delayed mutual coupling. Based on the invariance principle of differential equations, an adaptive feedback scheme is proposed for the stability of isochronal synchronization between two identical chaotic systems. Unlike the usual linear feedback, the variable feedback strength is automatically adapted to isochronally synchronize two identical chaotic systems with delay-coupled, so this scheme is analytical, and simple to implement in practice. Simulation results show that the isochronal synchronization behavior is determined by time delay.

无线电能传输系统最大效率追踪及恒压输出复合控制方法

针对无线电能传输(WPT)系统的传输效率受耦合线圈之间的互感以及负载影响的特点,该文提出一种基于阻抗匹配技术的最大效率追踪及基于前馈PI控制的恒压输出复合控制方法。首先,对双边LCC型WPT系统的参数和传输效率进行分析,通过调整系统参数优化系统的传输效率。其次,在二次侧使用DC-DC变换器采用阻抗匹配的方法实现最大效率追踪,同时在一次侧采用DC-DC变换器利用前馈PI控制器闭环控制负载端电压实现恒压输出。该方法中,效率追踪和电压控制之间相互独立,互不干扰。此外,该方法还通过系统工作时的电路参数来估算线圈间的互感值,并通过线性拟合的方法对该估算互感值进行修正,得到更精确的互感估算值。最后,通过搭建实验平台验证了该方法的可行性和有效性。与PI控制相比,前馈PI控制方法在快速性和抗扰动性上均具有明显优势。

融合均值榜样的反向互学习水母搜索算法

为解决水母搜索算法(jellyfish search algorithm,JS)的洋流运动缺乏多样性、群内运动缺乏引导性、种群间信息无交流,造成搜索速度慢、稳定性差及易早熟的问题,构建了一种融合均值榜样的反向互学习水母搜索算法(oppositional-mutual learning jellyfish search algorithm based on mean-value example,OMLJS).首先在水母跟随洋流运动(全局搜索)部分,利用前两代水母的平均位置代替只考虑上一代水母的平均位置来引导水母个体的位置更新,提高算法的全局搜索能力;其次在水母的群内主动运动(局部搜索)部分,利用最优个体代替随机个体来引导水母进行更有效的搜索,加快算法的收敛速度;然后在水母进入下一次迭代前增加对水母种群进行动态反向互学习步骤,增加种群多样性及增强种群间的信息交流,达到互补另外两个策略,提高算法的整体优化性能.选用12个经典的基准测试优化函数,将OMLJS与5个对比算法从解的平均值、最优值及方差进行对比分析,并用于求解最小生成树问题,OMLJS能够更快地找到最小生成树.实验结果表明,OMLJS的收敛速度、求解精度明显提高.

微网功频振荡分析及阻尼联合控制策略

针对微电网多虚拟同步发电机(n-VSGs)并联运行时存在功率和频率振荡的问题,提出一种暂态自阻尼和互阻尼联合控制策略。本文首先对单VSG数学模型进行研究,推导出低阻尼比是造成自振荡主要因素;其次对双VSG数学模型进行研究,推导出互振荡环流功率是产生互振荡主要因素;提出自阻尼控制策略,增加暂态情况下的等效阻尼,弥补了由下垂系数和阻尼系数耦合问题导致的系统欠阻尼;提出互阻尼控制策略,利用虚拟阻抗特性,减小多机功频振荡实现互阻尼;最后提出阻尼联合控制策略,通过设计功率前馈提高系统自阻尼,设计频率前馈调整系统互阻尼,不影响稳态功率分配同时,实现多VSG频率功率联合控制。在MATLAB/Simulink中构建4VSG仿真模型,对所提出的控制策略进行验证,与传统下垂VSG控制相比较,阻尼联合控制策略能够协同抑制系统功频振荡,在保证系统功频稳定的同时改善了功频暂态性能指标,频率暂态时间从3.5 s缩减至0.7 s,功率超调量从11.11%抑制到3.70%。

城市轨道交通全自动运行场景下的智能管控平台研究

[目的]现有运营机制主要为运营管理制度驱动人员进行操作管理,运营人员通过电话或对讲设备沟通信息,并使用各自独立的专业系统下达运营管控指令,在系统与系统之间只有少数固定的联动,这种模式下运营管理人员负荷较高,阻碍了运营管控效率的进一步提升。研究全自动运行中严重影响运营、乘客、设备设施等安全的场景,探索全自动运行运营安全管控机制和智能管控平台,提升全自动运行线路运营安全管控水平。[方法]采用智能化、数字化、信息化、高可信等技术手段将静态的运营规则和工作制度提升为动态的联动联控和应急处置管控措施的方法;构建服务于车站、车辆以及中心调度等多岗位信息共享、协同处置机制和智能管控平台,提高故障应急处置以及排故效率。[结果及结论]上海全自动运行线路的实践证明,搭建运营安全智能管控平台,加强运营安全监督、构建关键岗位协同处置机制、实现制度驱动系统安全高效地进行专业设施设备联动联控、智能辅助决策等功能,能更好地保障和提升全自动运行线路的应急处置效率和运营安全管控水平。

抑制新能源并网系统谐振的逆变器阻抗适配支路参数设计方法

随着高比例新能源并网成为发展趋势,新能源并网系统谐振成为影响新型电力系统安全稳定的潜在因素。由于风光资源在时间尺度上存在互补特性,可以通过调整逆变器并网特性实现系统阻尼的分时互济。针对逆变器阻抗适配支路的参数设计问题,提出阻尼系数的优化设计方法。首先,推导了阻尼互济控制逆变器的输出阻抗表达式,结合阻抗的幅值和相位分析阻尼系数对输出阻抗的影响,提出阻尼系数的初选设计方法。随后,从系统稳定性角度分析电网阻抗与阻尼系数之间的关系,为阻尼系数的优化提供了依据。为解决固定阻尼给控制带来的限制问题,提出了一种阻尼系数自适应的阻尼互济控制,使得控制更加灵活有效。最后,通过仿真和实验验证了阻抗适配支路参数设计方法的准确性以及阻尼系数自适应算法的有效性。

基于价值函数分解和通信学习机制的异构多智能体强化学习方法

许多现实世界的系统可以被建模为多智能体系统,多智能体强化学习为开发这些系统提供了一种有效的方法,其中基于集中训练与分散执行范式的价值函数分解方法得到了广泛的研究.然而现有的价值分解方法一般缺乏通信机制,在处理需要通信学习的多智能体任务时表现不佳.同时,目前大多数通信机制都是针对同构多智能体环境设计的,没有考虑异构多智能体场景.在异构场景中,由于智能体动作空间或观测空间的异构性,智能体之间的信息共享并不直接.如果不能对智能体的异构性进行有效地建模处理,通信机制将变得无效,甚至会影响多智能体的协作性能.为了应对这些挑战,本文提出一个融合价值函数分解和通信学习机制的异构多智能体强化学习框架.具体地:(1)与采用同构图卷积网络的方法不同,该框架利用异构图卷积网络融合智能体的异构特征信息得到有效的嵌入;(2)利用通信学习模块获得的嵌入信息和局部观测历史计算每个智能体的动作价值,以选择和协调智能体的动作;(3)通过设计的互信息损失函数和价值函数分解模块的损失函数联合训练,能够有效地训练整个方法.本文首先在两个异构多智能体平台上进行实验,实验结果表明该方法能学到比基线方法更有效的策略,在两个平台上相比基线方法分别提高了 13%的平均奖励值和24%的平均胜率.此外,在交通信号控制场景中验证了该方法在现实系统中的可行性.

考虑电动汽车和蓄电池联合储能的交直流混合微电网功率协调控制策略

针对电动汽车作为灵活储能分散接入交直流混合微电网后过度依赖双向互联接口变换器进行子网间储能交互的问题,提出一种考虑电动汽车和蓄电池联合储能的交直流混合微电网功率协调控制策略。首先,考虑交、直流子网净功率和功率互济级最大传输功率作为约束条件,将其划分为四种运行状态,并进一步分析功率互济级功率传输方向和储能荷电状态,详细划分不同模式对应的具体工况;然后,考虑电动汽车和蓄电池的响应优先级,设计联合储能动作规则,并详细研究交、直流子网和联合储能子网间的功率交互,制定功率协调控制策略,提出系统模式及工况切换方法;最后,基于Matlab/Simulink仿真平台搭建了交直流混合微电网仿真模型对所提控制策略进行验证。

基于等效负载跟踪的旋转磁场耦合式WPT系统最大效率控制方法

针对旋转磁场耦合式无线电能传输(WPT)系统在负载和耦合线圈互感变化条件下的最大效率和恒压输出需求,本文提出了一种基于等效负载跟踪的最大效率控制方法。首先,构建了以双层正交DD(DQDD)线圈为发射机构,交叉偶极式(CD)线圈为接收机构的旋转耦合式WPT系统;继而在考虑交叉耦合及线圈内阻的情况下进行了双能道LCC-S型WPT系统的谐振参数配置,推导了系统传输功率和效率的表达式。然后,引入复合控制方法,在直流输入端采用Buck电路来调节系统输出电压,在输出负载端采用Buck-Boost升降压电路实现阻抗匹配。最后,通过仿真与实验验证了所推导的回路电流、输入输出功率以及效率表达式的准确性,验证了计及耦合环流的谐振元件参数配置条件的可行性。结果证明了互感辨识结果的准确性,系统可以实现最大效率跟踪及恒压输出,传输效率可以保持在90%以上。

孤岛模式下交直流混合微电网互联变流器新型控制策略

孤岛模式下交直流混合微电网可以通过互联变流器(interlinking converter,IC)实现交流微电网和直流微电网的功率互济。针对孤岛模式下IC采用传统下垂控制和基于比例积分(proportional-integral,PI)的电流控制方案存在惯性小、动态性能差的问题,提出了基于虚拟同步机(virtual synchronous generator,VSG)的新型控制策略。首先,在传统下垂控制的基础上,通过引入交流频率和直流电压的微分量,提出了改进的VSG控制方法,以提升系统的电压和频率稳定性。然后,在IC的电流环,提出了固定时间滑模控制(sliding mode control,SMC)方法,提高了系统的动态性能。接着,在交流微电网和直流微电网中引入了功率二次控制,实现了系统电压和频率恢复。最后,基于远宽StarSim硬件在环实时仿真平台搭建的交直流混合微电网模型,验证了所提新型控制策略可以实现交直流微电网子系统间功率互济,提升了系统的惯性和动态控制性能。