事件触发下网络控制系统的动态输出反馈控制

研究了基于事件触发的网络控制系统(NCSs)的动态输出反馈控制(DOFC).通过综合考虑NCSs中的网络诱导延迟和时序错乱的问题,建立了包含事件触发机制和DOFC的闭环模型.与传统的静态控制不同,DOFC可以忽略极点配置受限的问题,增加系统的适应性范围.仿真结果验证了所提出的事件触发机制和DOFC的有效性.     

受控的大电流紧凑型汽车动力系统

功率控制设备的用户使用第三方系统已经很多年了,因为它们能够降低开发成本,缩短产品的面市时间,易于满足鉴定标准。由于规范要求越来越多,有必要采用更高集成度以及对更加严格地控制系统中的所有元件。     

一种适用于SC-FDMA多小区系统的协作调度和功率控制算法

该文针对长期演进(LTE)上行单载波频分多址(SC-FDMA)多小区系统的性能受限于小区间干扰的问题,提出一种综合考虑协作调度和功率控制的方案。该方法分步执行小区间的协作调度和功率控制,首先调度各小区中的用户,在此基础上优化用户的发射功率。调度时首先估计小区间的干扰信息并分配频率资源块给每个小区内的用户,在优化用户的发射功率时,同时考虑由于用户功率改变所造成的目标小区和其他干扰小区性能的变化。进一步提出一种低复杂度功率控制方案,在优化目标小区用户的功率时,只考虑受目标小区干扰影响最大的几个小区性能的变化,其他干扰小区性能的变化则通过引入补偿因子来估计。计算机仿真验证了该文所提方法在系统吞吐量和小区边缘吞吐量方面的性能优势显著。     

协作多基站多用户MIMO系统中有限反馈比特分配方案

For the cooperative multi-cell systems with multi-user MIMO, a new limited feedback bit allocation scheme is proposed to minimize the rate loss caused by quantization error. In the proposed scheme, the Channel State Information (CSI) feedback of cell-edge user for the local service cell and the adjacent interference cell are separately quantized. Based on the upper bound of the rate loss of cell-edge user due to the limited feedback, the number of feedback bits for quantized CSI of the local service cell and the adjacent cell are optimized with the fixed total bits of the limited feedback. The simulation shows that our proposed scheme of feedback bits allocation efficiently decreases the interference and increases the rate of systems compared with that of equal bits allocation and those of other allocations .     

具有高阶分集的协作系统中的功率分配算法

针对具有高阶分集的协作系统采用平均功率分配(EPA),导致系统平均误比特率性能较低的问题,提出了以最小化系统平均误比特率为目标的功率优化分配(OPA)算法。首先,推导了协作系统端到端误比特率的上界以及高信噪比条件下的渐近近似。在此基础上,推导了使系统平均误比特率最小的最优功率分配系数的闭式表达式。仿真结果表明,在保证总发射功率一定的条件下,所提功率分配算法相比平均功率分配可以有效降低系统的平均误比特率。     

电动汽车用动力电池环境下的安全性能

随着以锂离子蓄电池为代表的新能源汽车的推广与普及,就动力电池本身来说,在不同环境条件下的安全使用是至关重要的,其安全性能应结合电动汽车用锂离子蓄电池在充放电、行驶、环境温度变化和意外事故发生时可能出现的各种情况下,确保锂离子蓄电池进行有效的防护,不爆炸,不起火,避免灾害的发生.     

改进的扰动LPV系统输出反馈预测控制

针对一类带有有界状态干扰的多胞描述LPV系统,文中提出了一种鲁棒预测控制改进方法,并设计了保证系统渐近稳定的输出反馈控制器。为抵消有界状态干扰,该控制器考虑无扰动LPV系统,基于离线状态观测器,采用线性矩阵不等式求解预测控制无穷时域最小-最大优化问题。随后利用离线状态观测器获得扰动LPV系统与无扰动LPV系统状态的估计值之差,以确定保性能的反馈增益,从而得到使扰动LPV系统渐近稳定的最优偏移量,并将其与无扰动系统控制律组合作为最优控制律施加于实际系统。实验结果表明,运用改进的鲁棒预测控制方法能获得较好地控制性能,同时提高了系统的稳定性和解决优化问题的效率,仿真试验也验证了该算法的有效性。     

Power Control for Fading Cooperative Multiple Access Channels

For a fading Gaussian multiple access channel with user cooperation, we obtain the power allocation policies that maximize the average rates achievable by block Markov superposition coding, subject to average power constraints. The optimal policies result in a coding scheme that is simpler than the one for a general multiple access channel with generalized feedback. This simpler coding scheme also leads to the possibility of formulating an otherwise non-concave optimization problem as a concave one. Using the perfect channel state information available at the transmitters to adapt the powers, we demonstrate gains over the achievable rates for existing cooperative systems.     

最佳中继协作通信系统的功率分配算法

 为提高基于最佳中继选择的协作通信系统的性能,提出了以最小化系统中断概率为目标的功率分配算法.首先建立了系统的优化模型并证明了待解的优化问题实质是凸优化问题,由此提出了最优功率分配算法并给出了算法步骤.其次,在此基础上提出了一种有效的次最优功率分配算法,该算法计算简单且仅需已知各个中继节点的平均信道状态信息,无需在传输中实时更新,因而不增加系统的额外开销.仿真结果表明,本文提出的最优算法和次最优算法所得到的功率分配方案与穷举搜索方法的结果非常接近;与等功率分配方案相比,这两种算法均能显著提高系统的中断概率性能.     

网络控制系统反馈调度器的设计

本文提出一种基于反馈机理的网络控制系统动态调度器的设计方法.首先利用网络监测器在线获取当前的网络带宽和网络传输误差,预测下一监测器采样周期内可利用的网络带宽.然后利用网络带宽预测值和网络传输误差确定各控制回路采样周期的调节规律,并给出反馈调度器的可调度性约束.当数据包传输发生冲突时,采用MEF(Maximum Error First)作为辅助调度策略,确定数据包的发送优先级.最后通过一组仿真结果验证了所设计的反馈调度器的有效性.     

非线性闭环系统的虚拟参考反馈校正控制设计

针对闭环非线性系统中的控制器为一非线性函数的情况,采用虚拟参考反馈校正控制的设计原理,根据控制器的输入—输出观测数据构造一个基于输出数据的线性仿射函数。通过最小化逼近误差,利用系统辨识的参数估计方法求取线性仿射函数中可调参数权值,从而采用一个含可调参数权值的线性仿射形式来逼近原非线性控制器,通过对参数权值的调整使得逼近误差较小,并给出参数权值的凸优化求解过程。最后用仿真算例验证方法的有效性和可行性。     

Passivity-based Control for Markovian Jump Systems via Retarded Output Feedback

This paper is concerned with the problem of passivity-based control for Markovian jump systems via retarded output feedback controllers. A delay-dependent passivity criterion is obtained in terms of linear matrix inequalities. Based on this, a sufficient condition is proposed for the design of a retarded output feedback controller which ensures that the closed-loop system is passive. By using the sequential linear programming matrix method, a desired retarded output feedback controller can be constructed. Numerical examples are provided to demonstrate the advantage and effectiveness of the proposed method.     

Improvement of State Feedback Controller Design for Networked Control Systems

A new method is proposed to improve the state feedback controller design for networked control systems (NCSs) taking both network-induced time delay and packet dropout into account in this paper. An appropriate Lyapunov functional is introduced to establish the improved sufficient stabilizability conditions for NCSs with memoryless state feedback controller by considering an additional useful term when estimating the upper bound of the derivative of Lyapunov functional and introducing new free weight matrices. Based on this less conservative existence condition, a networked controller design method is derived, which is equivalent to the solvability of a set of linear matrix inequalities. Numerical example is given to demonstrate the effectiveness and benefits of the proposed method.     

Output Feedback H ∞ Control for 2-D State-Delayed Systems

In this paper, we consider a class of two-dimensional (2-D) local state-space (LSS) Fornasini–Marchesini (FM) second models with delays in the states, and we study delay-independent and delay-dependent H _∞ control problems via output feedback. First, based on the definition of H _∞ disturbance attenuation γ for 2-D state-delayed systems, we propose a delay-dependent bounded real lemma. Specifically, a new Lyapunov functional candidate is introduced and free-weighting matrices are added to the difference Lyapunov functional for 2-D systems possessing two directions. Then delay-independent and delay-dependent output feedback H _∞ controllers are developed that ensure that the closed-loop system is asymptotically stable and has H _∞ performance γ in terms of linear matrix inequality (LMI) feasibility. Furthermore, the minimum H _∞ norm bound γ is obtained by solving linear objective optimization problems. Numerical examples demonstrate the effectiveness and advantages of the LMI approach to H _∞ control problems for 2-D state-delayed systems. This work was supported in part by the National Natural Science Foundation of China (60525303 and 60604004), NSF of Hebei Province (08M008) and the Key Scientific Research Project of the Education Ministry (204014).     

一种低反馈开销多用户MIMO-OFDM系统功率最小化方案

该文利用凸规划理论中的库恩-塔克条件,为基于TCM编码的多用户MIMO-OFDM系统中实时业务资源优化问题提出了一种低反馈开销的功率最小化方案。该方案首先设计速率、功率和等效信道量化门限的码本,然后根据当前的信道状态信息分配子载波并对等效信道增益量化,最后基站给用户广播资源分配结果。仿真结果表明：相比其它方案,该文提出的方案有效降低系统能耗并且具有反馈开销低的特点。     

Power Control Algorithms for Satellite Communication Systems

Three different ground terminal transmit power control concepts for a Satcom system are examined. The effectiveness of constant satellite power (CSP) sharing among the carriers and adaptive satellite power (ASP) sharing is compared with constant ground terminal transmit power (CTP). It is shown that ASP offers substantial advantages over CSP in combating environmental degradations and that both can increase link availability with respect to the constant power (CTP) case. The effectiveness of the ASP control technique is shown to depend on the interconnectivity of the network if multidestinational carriers are used. The measurements required for system control, as well as their accuracies, are described.     

Uplink Power Control for MIMO-OFDMA Cellular Systems

In this paper, we propose a novel uplink power control algorithm, SMST, for multiple-input multiple-output orthogonal frequency-division multiple access (MIMO-OFDMA).We perform an extensive system-level simulation to compare different uplink power control algorithms, including the FPC adopted in 3GPP LTE and LTE-Advanced. Simulations show that SMST adopted in IEEE 802.16m outperforms other algorithms in terms of spectral efficiency, cell-edge performance, interference control, and trade-off control between sector-accumulated throughput and cell-edge user throughput. The SMST performance gain over FPC can be more than 40%.     

基于认知无线电系统的协作中继分布式功率分配算法

协作通信与直接通信相比能够显著地提高系统性能。协作通信中的一个关键问题是管理中继节点及有效地进行功率分配。尤其对于频谱共享的认知无线电(Cognitive Radio,CR)系统,协作方案的设计不仅要最大限度地提高认知网络协作的功率效率,而且需要最小化对主系统的干扰。该文针对认知无线电系统的协作通信问题,在多个中继节点与源节点协同通信的场景下,提出了一种基于放大转发(Amplify and Forward,AF)模式下的功率分配及联合优化算法,在保证主系统传输性能不受影响的前提下,提高认知系统的传输速率。仿真结果表明该文提出的自适应协作传输方案,和直接传输及等功率传输方案相比获得了进一步的性能增益,中断概率显著下降。     

Feedback Linearization Control of Three-Phase UPS Inverter Systems

In this paper, a feedback linearization technique is proposed to control the output voltage control of three-phase uninterruptible power supply systems. First, a nonlinear model including the output $LC$ filters is derived from the power balance condition between the inverter output terminal and the load side. Then, input–output feedback linearization is applied to the nonlinear model to make it linear. The controller of the linearized model is designed by linear control theory. The tracking control law is obtained with a pole placement technique. It is shown experimentally that the proposed control scheme gives high dynamic responses in response to load variation as well as a zero steady-state error.