基于自校正模型的感应电机鲁棒预测电流控制

有限集模型预测控制以其概念直观、动态响应快及易于处理非线性约束等优点,近年来成为电力驱动理论的国际研究前沿。然而,在感应电机有限集模型预测电流控制中,失配的电机参数将导致控制性能下降、电流谐波增大,甚至引起系统失稳。针对此问题,提出了一种基于自校正模型的感应电机鲁棒预测电流控制。首先,分析了失配电阻参数及励磁电感参数对电流矢量预测误差的影响规律。其次,摒弃了传统预测电流控制中的开环式预测模型,提出了定子电流自校正预测模型的构建原理及稳态性能计算方法。自校正模型是一种闭环式的架构,其可有效抑制失配参数引起的预测误差。最后,通过实验验证了所提方法的有效性,并从动态性能、瞬态性能及稳态性能等三方面综合评估了所提方法与传统的预测电流控制。     

基于块控原理的变结构控制

针对一类非匹配不确定性的线性系统 ,基于块控原理 ,提出了一种变结构控制设计方法 .利用反演设计方法来处理系统中的非匹配不确定性 ,再用变结构控制方法来改善系统的性能 .仿真实例证明了所提出的方法的正确性和有效性     

Continuous Finite‐Time Sliding Mode Control for Uncertain Nonlinear Systems with Applications to DC‐DC Buck Converters

This paper investigates the continuous finite‐time control problem of high‐order uncertain nonlinear systems with mismatched disturbances through the terminal sliding mode control method. By constructing a novel dynamic terminal sliding manifold based on the disturbance estimations of high‐order sliding mode observers, a continuous finite‐time terminal sliding mode control method is developed to counteract mismatched disturbances. To avoid discontinuous control action, the switching terms of a dynamic terminal sliding manifold are designed to appear only in the derivative term of the control variable. To validate its effectiveness, the proposed control method is applied to a DC‐DC buck converter system. The experimental results show the proposed method exhibits better control performance than a chattering free controller, such as mismatched disturbances rejection and smaller steady‐state fluctuations.     

High-efficiency,thin-film InP concentrator solar cells

High-efficiency, thin-film InP solar cells grown heteroepitaxially on GaAs and Si single-crystal bulk substrates are being developed as a means of eliminating the problems associated with using single-crystal InP substrates (e.g., high cost, fragility, high mass density and low thermal conductivity). A novel device structure employing a compositionally graded Ga _x In_1−x As layer (∼8 μm thick) between the bulk substrate and the InP cell layers is used to reduce the dislocation density and improve the minority carrier properties in the InP. The structures are grown in a continuous sequence of steps using computer-controlled atmospheric-pressure metalorganic vapor-phase epitaxy (AP-MOVPE). Dislocation densities as low as 3×10⁷ cm⁻² and minority carrier lifetimes as high as 3.3 ns are achieved in the InP layers with this method using both GaAs or Si substrates. Structures prepared in this fashion are also completely free of microcracks. These results represent a substantial improvement in InP layer quality when compared to heteroepitaxial InP prepared using conventional techniques such as thermally cycled growth and post-growth annealing. The present work is concerned with the fabrication and characterization of thin-film InP solar cells designed for operation at high solar concentration (∼100 suns) which have been prepared from similar device structures grown on GaAs substrates. The cell performance is characterized as a function of the air mass zero (AM0) solar concentration ratio (1–100 suns) and operating temperature (25°–80° C). From these data, the temperature coefficients of the cell performance parameters are derived as a function of the concentration ratio. Under concentration, the cells exhibit a dramatic increase in efficiency and an improved temperature coefficient of efficiency. At 25° C, a peak conversion efficiency of 18.9% (71.8 suns, AM0 spectrum) is reported. At 80° C, the peak AM0 efficiency is 15.7% at 75.6 suns. These are the highest efficiencies yet reported for InP heteroepitaxial cells. Approaches for further improving the cell performance are discussed.     

CVD金刚石膜在光滑衬底表面成核研究的进展

本文叙述了化学气相沉积金刚石薄膜过程中，金刚石在光滑非金刚石衬底表面的成核行为，讨论了目前用于提高金刚石成核密度的一些典型方法的优点和不足。     

Buck变换器的改进型互补滑模控制

针对Buck变换器系统中存在匹配和不匹配干扰的问题, 本文提出了一种基于干扰观测器(DOB)的改进型互补滑模控制(CSMC)策略. 首先, 建立存在多重干扰的Buck变换器数学模型, 将模型改写为标准二阶积分型控制对象, 将式中干扰统一为匹配干扰和不匹配干扰. 其次, 设计2个DOB分别估计匹配干扰和不匹配干扰, 实现有限时间内跟踪干扰信号, 以抵消各种不确定性对系统的影响. 然后, 设计互补滑模面, 提出基于等效控制的改进型互补滑模控制律, 保留边界层内鲁棒性的同时, 提升控制器的动态性能, 减小静态误差, 拓宽边界层参数选择范围. 最后, 基于李雅普诺夫理论证明所提出控制器的稳定性. 数字仿真表明, 提出的改进型CSMC控制器结合DOB的总体控制方案能够有效抑制系统匹配和不匹配干扰, 同时获得更快的收敛速度以及更高的跟踪精度.     

MIMO雷达稳健的自适应失配滤波器设计算法

针对发射导向矢量存在未知误差的问题,提出了一种MIMO雷达稳健的自适应失配滤波器(Robust Adaptive Mismatched Filter,RAMiF)设计算法.该算法在稳健的接收波束形成算法的基础上,对其输出做稳健的失配滤波处理,以一定的主瓣电平损失为代价换取更低的旁瓣电平,从而提高系统对发射导向矢量误差的稳健性.仿真结果表明该滤波器在信噪比较高的情况下对发射导向矢量误差具有自适应的稳健性.     

Design of decentralised adaptive sliding mode controllers for large-scale systems with mismatched perturbations

Based on the Lyapunov stability theorem, a methodology for designing a decentralised adaptive sliding mode control scheme is proposed in this paper. This scheme is implemented for a class of large-scale systems with both matched and mismatched perturbations. The perturbations and the interconnection terms are assumed to be norm bounded under certain mild conditions. The decentralised sliding surfaces with adaptive mechanisms embedded are specially designed for each subsystem, so that when each subsystem enters the sliding mode, the mismatched perturbations and the effects of interconnections can be effectively overcome and achieve asymptotic stability. The decentralised controller with embedded adaptive mechanisms is capable of driving the controlled state trajectories into the designated sliding surface in finite time. This is also achieved without the knowledge of upper bounds of the perturbations except those of the uncertainties in the input channels. A numerical example is included to demonstrate the feasibility of the proposed control scheme.     

Composite predictive flight control for airbreathing hypersonic vehicles

The robust optimised tracking control problem for a generic airbreathing hypersonic vehicle (AHV) subject to nonvanishing mismatched disturbances/uncertainties is investigated in this paper. A baseline nonlinear model predictive control (MPC) method is firstly introduced for optimised tracking control of the nominal dynamics. A nonlinear-disturbance-observer-based control law is then developed for robustness enhancement in the presence of both external disturbances and uncertainties. Compared with the existing robust tracking control methods for AHVs, the proposed composite nonlinear MPC method obtains not only promising robustness and disturbance rejection performance but also optimised nominal tracking control performance. The merits of the proposed method are validated by implementing simulation studies on the AHV system.