Multimodule parallel series-loaded resonant converters

The design and implementation of a multimodule parallel series-loaded resonant (SLR) converter system is presented. The SLR converter to be paralleled is operated in the n=2 discontinuous mode (DCM). Its dc analysis and dynamic modeling are made. In parallel operation, an average control technique is proposed to compensate the mismatch in current control characteristics of each parallel converter. Good dynamic and static current sharing characteristics are obtained. In addition, to obtain good output voltage regulating control performance, a design procedure is presented to find the parameters of feedback voltage controller according to the prescribed specifications     

Current distribution control for parallel connected converters. I

For pt.II, see ibid., vol.28, no.3, p.841-851 (1992). A master-slave control scheme for a uniform current distribution among converter modules in a parallel connected system is presented. In this technique, inner current loops are introduced to the system to achieve output current equalization. The current distribution error is used as a criterion for judging system performance. Using this control scheme, the current distribution error can be reduced greatly even with nonidentical converters in the system. To optimize system efficiency and facilitate the fault-tolerant algorithm realization, this technique is refined so that only the necessary number of converters are activated for different load conditions     

Full control of a PWM DC-AC converter for AC voltage regulation

The design and implement action of a DSP-based fully digital-controlled single-phase pulsewidth modulated (PWM) dc-ac converter for ac voltage regulation is described. The proposed multiloop digital controller (MDC) consists of a current controller, a voltage controller, and a feedforward controller. This MDC was realized using a single-chip digital signal processor (DSP). The PWM gating signals are determined at every sampling instant by the proposed multiloop digital control scheme using a set of detected feedback signals. A software current control; scheme has been developed to achieve fast current control of the PWM inverter and decouple the inductor of the output filter. Experimental results have been given to verify the proposed digital control scheme. The constructed DSP-based PWM dc-ac converter system can achieve fast dynamic response and with low total harmonic distortion (THD) for rectifier type of loads     

ACSS for paralleled multi-inverter systems with DSP-based robust controls

An averaged current-sharing strategy (ACSS) for paralleled multi-inverter systems with digital signal processor (DSP)-based robust controls is presented. With an ACSS, the inverters are in parallel operation and each inverter has a voltage robust controller to achieve system stability and robustness, and a current robust controller to track the averaged inductor current of the inverters to achieve equal current distribution. In the proposed system, the current-sharing control loop is independent of the voltage control loop. Therefore, equal current distribution among the inverters, fast response, and tight regulation can be achieved. Additionally, the ACSS in each inverter can be readily implemented with two operational amplifiers. Simulation results and hardware measurements or a single-inverter system and a two-inverter system, and simulation results of a three-inverter system with linear and nonlinear loads have demonstrated the feasibility of the proposed control scheme in equal current distribution and fast regulation.     

基于径向基神经网络干扰观测器的空天飞行器自适应轨迹线性化控制

 研究了一种自适应轨迹线性化控制策略并应用于空天飞行器(ASV)飞行控制系统设计。通过理论分析指明当前轨迹线性化控制方法(TLC)对系统中的不确定存在鲁棒性不足的问题。为了解决这一问题,首先研究了一种径向基神经网络干扰观测器(RDO)技术,严格证明了RDO对于系统中不确定因素具有良好的逼近能力。然后利用RDO输出得到一种新的基于RDO的自适应TLC控制策略。神经网络自适应律采用Lyapunov方法设计,保证了闭环系统所有信号有界。最后采用新方案实现了ASV飞控系统,仿真结果表明整个闭环系统在鲁棒性能方面得到很大提高。     

THE ROBUST OBSERVER FOR FAULTDETECTION OF THE SENSOR

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Coordinate Conversion and Tracking for Very Long Range Radars

The problem of tracking with very long range radars is studied in this paper. First, the measurement conversion from a radar's r-u-v coordinate system to the Cartesian coordinate system is discussed. Although the nonlinearity of this coordinate transformation appears insignificant based on the evaluation of the bias of the converted measurements, it is shown that this nonlinearity can cause significant covariance inconsistency in the conventionally converted measurements (CM1). Since data association depends critically on filter consistency, this issue is very important. Following this, it is shown that a suitably corrected conversion (CM2) eliminates the inconsistency. Then, initialized with the converted measurements (using CM2), four Cartesian filters are evaluated. It is shown that, among these filters, the converted measurement Kalman filter with second order Taylor expansion (CM2KF) is the only one that is consistent for very long range tracking scenarios. Another two approaches, the range-direction-cosine extended Kalman filter (ruvEKF) and the unscented Kalman filter (UKF) are also evaluated and shown to suffer from consistency problems. However, the CM2KF has the disadvantage of reduced accuracy in the range direction. To fix this problem, a consistency-based modification for the standard extended Kalman filter (E1KF) is proposed. This leads to a new filtering approach, designated as measurement covariance adaptive extended Kalman filter (MCAEKF). For very long range tracking scenarios, the MCAEKF is shown to produce consistent filtering results and be able to avoid the loss of accuracy in the range direction. It is also shown that the MCAEKF meets the posterior Carmer-Rao lower bound for the scenarios considered.     

检测传感器故障的鲁棒观测器

介绍一种在系统参数变化情况下进行故障检测的观测器。对观测器采用特征值、特征向量进行联合配置的算法 ,并对估计误差设计奇偶空间 ,使各传感器的故障在奇偶空间中被解耦分离 ,因而可用一个观测器检测与分离多路故障传感器 ,实现了故障检测的鲁棒性     

Inverted decoupling and LMI-based controller design for a turboprop engine with actuator dynamics

The main objective of the turboprop engine control system is to ensure propeller absorbed power at a constant propeller speed by controlling fuel flow and blade angle. Since each input variable affects the selected output variables, there exist strong interactions between different control loops of a Two-Spool TurboProp Engine (TSTPE). Inverted decoupling is used to decouple the interactions and decompose the TSTPE into two independent single-input single-output systems. The multi-variable PI controller and two single-variable PI controllers are designed for the TSTPE with actuator dynamics based on Linear Matrix Inequality (LMI), respectively, which is derived from static output feedback and pole placement condition. The step responses show that due to the difference in the response times of the selected output variables, it is difficult to design an appropriate multi-variable PI controller. The designed single-variable PI controllers are tested on the TSTPE integrated model to illustrate the effectiveness of the proposed method, that is, the interactions are first decoupled and then the controllers are designed, and the resulting simulated responses show that compared with the controller designed without actuator dynamics, the gas-generator shaft speed and power turbine shaft speed can better track their respective commands under the action of the controller designed with actuator dynamics.     

Neural and fuzzy reconstructors for the virtual flight datarecorder

The results are presented of a comparative study evaluating the performance of neural network (NN) and fuzzy logic reconstructors (FLRs) for the development of a virtual flight data recorder (VFDK). Typical flight data recorders (FDRS) on commercial airliners do not record the aircraft control surface deflections. These dynamic parameters are critical in the investigation of an accident or an uncommanded maneuver. The results are shown relative to a VFDR based on a neural network simulator (NNS) along with a neural network reconstructor (NNR) or a FLR The NNS is trained off-line, using available flight data for the particular aircraft, for the purpose of simulating any desired dynamic output recorded in current FDRs. The NNS is then interfaced with the NNR or with the FLR. The output of the two reconstructors are the control surface deflections which minimize a performance index based on the differences between the available data from the FDR and the output from the NNS. The study tested with night data from a B737-300 shows that both schemes, the one with the NNR and the one with the FLR, provide accurate reconstructions of the control surface deflections time histories     

满足二次稳定及干扰抑制性能指标的航空发动机H∞控制器设计

对于一类状态及输出矩阵存在结构参数摄动的对象,本文提出了闭环系统满足二次稳定性及干扰抑制性能的动态输出反馈控制器的理论设计方法,随后进行的仿真结果表明,所设计的控制器满足要求。      

基于DSC整流器和双闭环PR逆变器的模块化中频静变电源

与传统中频电源相比,模块化中频静变电源具有选用灵活、可靠性高、冗余性好、便于系统维护等优点。中频静变电源整流器在控制母线电压稳定的同时还要实现单位功率因数控制。为此,具体分析了双电流环控制策略,给出了双电流环控制器中电压电流正负序分离原理和双dq锁相环的具体实现方法,即延时信号抵消(DSC)和双闭环准比例谐振(PR)。针对逆变器输出电压基波无差跟踪困难、谐波含量高等问题,采用双闭环多重准PR控制策略,实现中频电压的稳定输出。仿真和试验结果表明,双电流环控制器能同时实现母线电压稳定和单位功率因数控制,采用双闭环多重准PR控制策略的中频逆变器能够输出稳定的中频交流电压。     

应用LQG方法在生产—库存管理系统中的应用研究

给出线性二次型最优输出跟踪问题的系统方程和目标函数,对目标函数中每一项的实际意义做出分析,并讨论了加权矩阵中元素的选取。给出控制规律的最优解,并对最优控制与预期输出的关系做出分析。给出一个生产—库存管理模型,分析了该模型应满足的状态方程,从而说明了它是一个可观测系统,且可以用线性二次型最优输出跟踪问题来解决。最后用具体实例验证了方法的有效性。     

A new power collection architecture for future spacecraft

The generalized tree-like transmission line network system having n layers in total with m-to-1 branch connection at each joint (T-TLNS-n-m) is proposed to replace the traditional series-parallel combined dc networks to automatically accumulate identically distributed power cells into the large amount of useful power for the spacecrafts. The proposed system has the attractive features of simple structure, easy construction and maintenance, and low cost, because two kinds of parts, ac current sources and m-to-1 transmission line (TL) branch connection parts, are used in the whole system. A method of implementing ac current cells having high output impedance is proposed to improve the power collection efficiency of the whole network system. Simulated results show that that low-pass nominal /spl pi/- or T-circuit with high characteristic impedance, which is used for the voltage source to current source converter in the current cell, improves the efficiency of the voltage inverter, filters out the harmonics, and increases the output impedance of the whole current cell.     

Adaptive fault-tolerant attitude tracking control for spacecraft with time-varying inertia uncertainties

This paper is devoted to adaptive attitude tracking control for rigid spacecraft in the presence of parametric uncertainties, actuator faults and external disturbance. Specifically, a dynamic model is established based on one-tank spacecraft, which explicitly takes into account changing Center of Mass(CM). Then, a control scheme is proposed to achieve attitude tracking.Benefiting from explicitly considering the changing CM during the controller design process, the proposed scheme possesses good robustness to parametric uncertainties with less fuel consumption.Moreover, a fault-tolerant control algorithm is proposed to accommodate actuator faults with no need of knowing the actuators' fault information. Lyapunov-based analysis is provided and the closed-loop system stability is rigorously proved. Finally, numerical simulations are presented to illustrate the effectiveness of the proposed controllers.     

励磁系统仿真模型校正技术研究

励磁控制系统作为同步发电机的重要组成部分,主要作用是向同步发电机的定子绕组提供一个可控的直流电流(电压),维持机端电压恒定,满足同步发电机的正常发电需要。通过发电机组控制系统模型,及时校正机组仿真模型,对异常响应进行预警排查,能够有效提高系统运行的稳定性。在MATLAB中搭建了一种以外部仿真机作为励磁调节器的单机无穷大系统仿真模型,模拟励磁系统PID主环异常以及电力系统稳定器(PSS)辅环异常时的输出,与理论值进行对比分析,能够及时确定故障原因和部位,实现故障维修。     

大型卫星太阳能帆板的分布式振动控制

针对大型卫星太阳能帆板（LSSP）振动主动控制器设计复杂、在轨扩展不易且容错性能有限等问题,提出一种适用于模块化结构的分布式振动控制方法。首先,根据LSSP的结构特点划分控制子模块,建立面向分布式控制的子模块动力学模型,并结合卡尔曼滤波算法设计各子模块线性二次最优振动控制器;然后,考虑各子模块之间的测量信息交互,提出应用于LSSP整体结构的分布式振动控制系统并分析闭环系统稳定性。最后,给出数值仿真算例以验证所提控制方法的有效性。结果表明,采用可扩展的分布式控制器,LSSP的振动能够得到有效抑制,且控制系统的容错性能良好。     

结构控制设计中具有输出反馈最小范数的极点配置方法

给出了结构控制系统输出反馈极点配置的设计方法,该方法采用鲁棒性分析设计的一些基本步骤,兼顾结构控制系统的鲁棒性和计算的简便。基于鲁棒度量建立状态向量和输出向量参数之间的协调关系,利用 QR分解技术,导出鲁棒极点配置问题的增益矩阵表达式,通过分析该表达式,可以得出本文方法的鲁棒性能够得到保证。将输出反馈极点配置问题转化为非线性最小二乘问题,用 LM方法解出具有最小范数的反馈矩阵。最后将本文方法应用一个 3层结构在正弦载荷作用下的振动控制问题,证实了本文方法的性能     

航空机电作动器的混合整流全状态反馈控制

研究了一种适用于多电飞机供电系统的新型混合整流电路,并针对航空机电作动器负载特殊的用电特性,提出了一种基于全状态反馈的混合整流控制方法,在保证整流效果的同时,解决了负载功率短时大范围变化引起的直流电压不稳定问题。这种新型混合整流电路将二极管整流电路和脉宽调制(PWM)整流电路并联输出接负载,两者共同承担有功功率且比例可控,通过适当控制PWM电路达到网侧低谐波的目的,且当负载制动时,能量可以回馈交流侧电网。建立了混合整流器的线性化全状态数学模型,设计了基于线性二次型(LQR)最优化理论的全状态反馈控制策略。通过在MATLAB/Simulink下的建模与仿真,比较了全状态反馈控制方法与传统三状态反馈控制方法,并在机电作动器样机上进行了实验验证。仿真和实验结果表明,采用全状态反馈控制的新型混合整流方案对于功率大范围变化负载具有更好的控制性能。     

航空发动机内置式永磁容错发电系统的研究

针对内置式航空发电系统高功率密度、高可靠性和高输出性能的要求,提出了基于三相四桥臂的航空用永磁容错发电系统。利用永磁容错电机大电感的特点,改进了传统弱磁控制算法,提出了简单高效的直轴电流I_d解析法弱磁控制,通过实时计算弱磁电流给定实现了宽速范围（3倍额定转速）内的恒压发电控制。同时,根据容错电机磁隔离的特点,以保证故障前后电机定子磁场为圆形旋转磁场为前提,结合电压空间矢量脉宽调制（SVPWM）算法实现了单相断路或短路故障的容错发电控制。通过MATLAB仿真验证了控制算法的正确性。最后,对一套7.5 kW永磁容错发电系统进行了算法验证实验,验证了I_d解析法弱磁控制和容错控制的可行性,为后续的系统性能测试打下基础。