计及螺旋桨负载的船舶电力系统协调控制设计

推进负载对船舶电网的暂态稳定性影响是船电系统的主要特征之一.本文基于非线性鲁棒L2干扰抑制控制方法,研究了具有螺旋桨负荷的船舶电力系统中的励磁与调速的协调控制问题,在充分分析了柴油发电机组的非线性数学模型及其螺旋桨负载的相互耦合的非线性动态结构特性的基础上,提出backstepping控制技术与L2干扰抑制相结合的综合协调控制策略来设计控制器.该控制器在保证系统稳定的条件下,有效地抑制干扰对发电机系统电压和频率的影响.仿真表明,在给系统突加螺旋桨负载的情况下,该控制器能有效地抑制负载对系统性能的影响,验证了控制器的有效性.     

执行机构带宽对动态逆方法的影响及解决方案

本文从理论上分析了执行机构带宽对动态逆闭环控制系统动态特性影响, 发现较低的执行机构带宽会在伪线性系统中引入一个非线性干扰项, 为此提出了两种方法来消除这个非线性干扰项, 一个是采用参考模型的思想设计补偿器提高执行机构子系统的等效带宽, 另一个思路则是直接在非线性反馈项中引入补偿直接对消非线性干扰项. 仿真结果表明, 两类方法都能较好地消除非线性干扰项, 直接补偿方法能精确消除干扰项, 但需要准确动力学模型, 提高等效带宽的方法虽然是近似的, 但能方便地引入自适应算法, 可以抑制执行机构模型参数不确定的影响.     

真空热试验通用软件平台工作模式与关键技术

针对由压力腔外界干扰、工作电压不稳定和压力检测误差等因素导致的零点漂移问题,基于自调谐整流和谐振自调技术研究了一种多压力传感器零点漂移消除算法;首先根据多压力传感器的外界干扰向量、内置电阻和非线性系数特性建立了三维分析空间,据此研究造成系统工作电压变化的外界干扰因素于是设计了自调谐整流电路,然后分析了保障多压力传感器处于谐振状态的必要条件,设计了谐振自调电路和功率放大器,最后提出了将自调谐整流和谐振自调相结合的零点漂移消除算法;验证实验从检测精度、抗外界干扰和系统稳定性等方面,证明了所提方案与紧凑型多压力传感器和电容式多压力传感器相比的优越性。     

时延系统预估补偿重叠控制法研究

1引言在工业过程控制系统中，对于具有纳时延特性的被控对象，一种有效的控制策略是采用Smith预估器。可将纯时延从闭环特征方程式中消除，从而可克服纯时延对控制性能的不利影响。任何控制系统均存在可测和不可测的干扰，为了使系统准确而迅速地跟踪参考输入的变化，对于典型的二队系统，常常以等效阻尼比ξ＝0．5～0．7为最佳。但是，这样会使系统抑制干扰作用的能力减弱，从而不利于克服干扰对系统的影响。另外可以设想，在（小于0．5～0．7时，系统对参考输入的响应会更快，同时克服干扰作用影响的能力更强。本文是针对纯时延系统，在…     

基于支持向量机的电流互感器零点误差非线性校正

为了提高电流互感器自动测试系统的测量精度,提出一种非线性的电流互感器零点误差校正算法(QPSO-LSSVM);采用量子粒子群优化的最小二乘支持向量机算法对电流互感器的零点误差进行自适应处理,消除零点误差对测量精度的影响;结果表明,QP-SO-LSSVM算法有效的抑制零点误差,提高电流互感器自动测试系统的测量精度;QPSO-LSSVM是一种有效的电流互感器零点误差非线性校正方法。     

基于模糊补偿的机械手鲁棒自适应模糊控制研究

多关节机械手系统中普遍存在摩擦特性、随机干扰及负载变化等非线性因素的影响。针对传统的PID控制和模糊控制很难对该类系统实现快速高精度的跟踪控制等问题,本文在模糊信息已知并且所有状态变量均可测得的情况下,设计了一种基于模糊补偿的鲁棒自适应模糊控制律。同时,为了减少模糊逼近的计算量,提高运算效率,采用了对不同的扰动补偿项加以区分、分别逼近的方法。仿真实验结果表明,这种改进的带模糊补偿的鲁棒自适应模糊控制可以很好地抑制摩擦、扰动及负载变化等非线性因素的影响。     

基于单参数模糊PID的水下发射控制系统

水下发射系统在工作过程中，由于受到负载转动惯量的变化、水阻力矩的影响，使系统的参数发生变化。应用常规的PID控制，难FA获得良好的动、静态性能；采用单参数模糊PID控制算法，只须调整α参数即可实现对PID三个参数的调整，经实验证明该方法简单，同时对抑制干扰、消除负载转矩变化的影响具有明显的效果。     

基于L2干扰抑制的水下机器人三维航迹跟踪控制

为实现自治水下机器人(AUV)的三维航迹跟踪控制,考虑了非线性水动力阻尼对AUV系统的影响和外界海流干扰作用,提出了基于L2干扰抑制的鲁棒神经网络控制方法.该方法基于李雅普诺夫稳定性理论,设计神经网络控制器补偿非线性水动力阻尼和外界的海流干扰,再将神经网络的估计误差当做AUV系统的外部干扰用L2干扰抑制控制器予以消除.最后针对某AUV进行了螺旋线三维下潜跟踪控制仿真实验,结果表明设计的控制器可以较好地克服时变非线性水动力阻尼对系统的影响,并对外界海流干扰有较好的抑制作用,可以实现AUV三维航迹的精确跟踪.     

BUCK变换器带恒功率负载反馈精确线性化控制

对BUCK交换器带恒功率负载系统的非线性控制进行了研究.根据恒功率负载的非线性特性,推导出BUCK变换器带恒功率负载的精确线性化反馈控制规律,设计了系统非线性控制器.用SABER软件对控制律进行了仿真,结果表明反馈精确线性化技术可以实现对BUCK变换器带恒功率负载的控制,在电源及负载大范围变化时,保证系统的稳定运行,具有大信号稳定特性.     

纯硬件开环电压型无死区半桥逆变器研究

随着新能源发电应用的不断推广,逆变器的重要性越发凸显。分析了单极性正弦脉宽调制(SPWM)驱动在纯电阻(弱感性)负载下实现无死区半桥开环逆变输出的可行性,介绍了一种适用于新能源发电的纯硬件开环电压型无死区半桥逆变器。该逆变器采用模块化和半桥开环逆变结构,有效避免了因干扰而导致的开关器件误损坏以及因设置死区时间而导致的基波电压损失,且输出电压波形较好。利用MATLAB软件进行系统仿真,所得结果与预期相符。由此表明:该逆变器可在闭环控制条件下维持系统稳定,并确保纯电阻(弱感性)负载下的逆变输出电压波形不失真。     

Decentralized control of sequentially minimum phase systems

Fundamental limitations in decentralized control of systems with multivariable zeros are considered. It is shown that arbitrary bandwidth can be obtained with a stable block-diagonal controller, if certain subsystems of the open-loop system fail to have zeros in the right half-plane and a high-frequency condition holds. Implications on control structure design and sequential loop-closuring methods are discussed     

Compensation of uncertain continuous systems by using the internal model control principle

In this paper the design of compensators for uncertain continuous plants is investigated. The standard derived compensators are based on the application of the internal model control (IMC) method. The required a priori knowledge on the plant is rather weak, namely, an upper bound of the plant relative order, the numbers of the strictly unstable and critically unstable plant poles being integrators and upper and lower bounds of the amplitude-versus-frequency plot over the low frequency band in the case of minimum-phase open-loop systems. If the open-loop system has unstable zeros and/or poles then the above bounds are required to be known for a modified magnitude plot which substitutes the unstable zeros (poles) by stable poles (zeros) which are their complex-conjugate reflections on the left-hand plane. An absolute upper bound of the open-loop phase plot is obtained on a finite frequency interval which allows the closed-loop system to guarantee a prescribed relative stability in many practical situations. The method is dependent on the alternative design of phase lead/lag classical compensators and to indirect adaptive control situations where the adaptive identifier is used for the parametrization of the adaptive controller.     

Design and experimental study of broadband hybrid energy harvester with frequency-up conversion and nonlinear magnetic force

In this paper, a novel broadband hybrid piezoelectric and electromagnetic energy harvester using in the low frequency vibration environment is proposed, which combines nonlinear magnet force and frequency-up conversion mechanism simultaneously. Performances are studied by theoretical analysis and experimental test. Electromechanical governed equations of harvester are established, and analytical solutions of vibration response, output voltage and power are derived. Then, effects of nonlinear force, spacing between low frequency vibration beam and piezoelectric beam, load resistance and input excitation on harvester performances are investigated by experimental test. It can be concluded that the harvester can be used to work at the low-frequency environment efficiently, and the resonant frequency and harvesting bandwidth can be tuned by the nonlinear force between the magnets and the spacing between beams. Moreover, the larger the nonlinear magnetic force and the smaller the distance between two beams, the lower working frequency and the larger bandwidth. Compared with the corresponding linear apartment, output power and bandwidth of proposed harvester are improved 90% and 125% respectively.

     

伺服电机驱动的连铸结晶器振动位移系统反步滑模控制

针对伺服电机通过偏心轴连杆机构驱动的连铸结晶器振动位移系统中存在减速比加工误差、偏心轴机械零位初始偏差和负载转矩扰动等问题,本文设计了一种基于双幂次趋近律和扩张状态观测器(ESO)的反步滑模控制器.首先,针对偏心轴转角到结晶器位移非线性关系逆解的非唯一性,可通过分段函数法建立结晶器位移到偏心轴转角一一对应的映射函数关系;其次,针对不可测的减速比加工误差和负载转矩扰动可采用扩张状态观测器来实时估计,以削弱扰动对系统跟踪性能的影响;最后,采用一种具有二阶滑模特性且有限时间收敛的双幂次趋近律以提高收敛速度和削弱抖振.仿真对比结果表明,本文所设计的控制器能有效实现连铸结晶器位移的渐近跟踪,并对系统扰动具有较强的鲁棒性.     

On disturbance propagation in leader–follower systems with limited leader information

This paper studies the problem of disturbance propagation in a string of vehicles aiming to proceed along a given trajectory while keeping a constant distance between each vehicle and its successor. It is assumed that each vehicle can control its position based on the spacing error with respect to the preceding vehicle in the string, as well as on coded information transmitted by the lead vehicle. Using information-theoretic techniques, this paper establishes a lower bound to the integral of the sensitivity function of spacing errors with respect to a stochastic disturbance acting on the lead vehicle. The derived bound depends on the open-loop poles and zeros of the vehicles’ dynamics as well as on the (possibly nonlinear) controller used at each vehicle. The lower bound is shown to be tight for a specific class of systems and controllers.     

Robust digital control of a DC–DC buck converter with low frequency samplings

A robust DC?CDC converter which can covers extensive load change and also input voltage changes with one controller is needed. Then the demand to suppress output voltage change becomes still severer. We propose an approximate 2-degree-of-freedom (2DOF) digital controller which realized start-up response and dynamic load response independently. The controller makes a control bandwidth wider, and at the same time makes variations of the output voltage small at sudden changes of a load and an input voltage. In this paper, a new approximate 2DOF digital control system with additional zeros is proposed. Using the additional zeros, the second-order differential transfer characteristics between equivalent disturbances and a output voltage are realized. Therefore, the new controller makes variations of the output voltage smaller and the sudden changes of the load and the input voltage. This controller is actually implement on a DSP and is connected to the DC?CDC converter. Experimental results demonstrate that this type of digital controller can satisfy given severe specifications with low frequency sampling.     

Reduced-order observer-based control design for nonlinear stochastic systems

In this paper, we investigate the stabilization control design problem of nonlinear stochastic SISO systems in strict-feedback form. By introducing a novel reduced-order observer, an output-feedback-based control is constructively designed, which renders the closed-loop system asymptotically stable in the large when the nonlinearities and stochastic disturbance equal zero at the equilibrium point of the open-loop system, and bounded in probability, otherwise. Besides, the obtained controller preserves the equilibrium point of the open-loop nonlinear system.     

Robust stability under a class of nonlinear parametricperturbations

This paper considers the robust stability verification of linear time-invariant systems admitting a class of nonlinear parametric perturbations. The general setting is one of determining the closed-loop stability of systems whose open-loop transfer functions consist of powers, products, and ratios of polytopes of polynomials. Apart from this general setting, two special cases of independent interest are also considered. The first special case concerns uncertainties in the open-loop gain and real poles and zeros, while the second special case treats uncertainties in the open-loop gain and complex poles and zeros. In light of the zero exclusion principle, robust stability is equivalent to zero exclusion of the value sets of the system characteristic function (a value set consists of the values of the characteristic functions at a fixed frequency). The main results of this paper are as follows. 1) The value set of the characteristic function at each fixed frequency is determined by the edges and some frequency-dependent internal line segments. 2) Consequently, Hurwitz invariance verification simplifies to that of checking certain continuous scalar functions for avoidance of the negative real axis. 3) For the case of real zero-pole-gain variations, the critical lines are all frequency independent, and therefore, the determination of the robust stability is even simpler. 4) For the case of complex zero-pole-gain variations, the critical internal lines are shown to be either frequency independent or to be confined in certain (two-dimensional) planes or (three-dimensional) boxes     

ANALYSIS AND DESIGN OF FEEDBACK CONTROL SYSTEMS WITH TRACKING ERRORS SQUARE

In this study, a command tracking error square control scheme is first proposed for analysis and design of feedback control systems. One of the tracking errors is low‐pass filtered and used in the feedback loop for gain adaptation; the other is used in the forward loop for command tracking control. The overall systems are nonlinear feedback systems, and can be reconfigured to an automatic gain control (AGC) loop with command tracking error input. The stability and robustness of the controlled systems are verified by time response, frequency response, and large parameter variation testing with a simple illustrating example and are finally applied to a complicated electro‐hydraulic velocity servo system with large load disturbance.     

Improved disturbance rejection with online adaptive pole-zero compensation on a Φ-shaped PZT active suspension

In feedback control systems, the anti-resonant zeros cannot be arbitrarily placed, hence degrading tracking performance as well as input disturbance and noise rejection capabilities due to reduced gain at the frequencies of the zeros. In this paper, an online adaptive inverse control with saturation (OAICS) algorithm is proposed for compensating the minimum phase resonant poles and anti-resonant zeros of a PZT active suspension using measured position error signal. Experimental results on a Φ-shaped PZT active suspension using laser Doppler vibrometer (LDV) shows the proposed OAICS is effective in cancelling the first two dominant minimum phase pole-zero pairs to achieve high servo bandwidth and low sensitivity servo system with small overshoot during set-point tracking.