Survey on Passivity Based Control of Induction Machine

Induction machines (IM) constitute a theoretically interesting and practically important class of nonlinear systems. They are frequently used as wind generators for their power/cost ratio. They are described by a fifth‐order nonlinear differential equation with two inputs and only three state variables available for measurement. The control task is further complicated by the fact that IM are subject to unknown (load) disturbances and the parameters can be of great uncertainty. One is then faced with the challenging problem of controlling a highly nonlinear system, with unknown time‐varying parameters, where the regulated output, besides being unmeasurable, is perturbed by an unknown additive signal. Passivity‐based control (PBC) is a well‐established structure‐preserving design methodology which has shown to be very powerful to design robust controllers for physical systems described by Euler‐Lagrange equations of motion. PBCs provide a natural procedure to "shape" the potential energy yielding controllers with a clear physical interpretation in terms of interconnection of the system with its environment and are robust vis á vis to unmodeled dissipative effects. One recent approach of PBC is the Interconnection and Damping Assignment Passivity‐Based Control (IDA‐PBC) which is a very useful technique to control nonlinear systems assigning a desired (Port‐Controlled Hamiltonian) structure to the closed‐loop. The aim of this paper is to give a survey on different PBC of IM. The originality of this work is that the author proves that the well known field oriented control of IM is a particular case of the IDA‐PBC with disturbance.     

Persistence of lower dimensional invariant tori in a class of reversible systems

In this paper we prove the persistence of lower dimensional invariant tori for a class of reversible systems without any non-degeneracy condition. In the proof, we use the special nature that the dimension of the frequency ω is 2 and the modified KAM iteration to prove the persistence of lower dimensional hyperbolic invariant tori, but the frequency has some small shifts from small perturbations.     

考虑锁相环的双馈风力发电机组无源控制

为了降低大规模变速风力发电机接入电网的运行风险,需要研究风力发电机组的控制策略,增加风电对系统功率振荡的抑制能力。该文通过锁相环实现dq坐标系定向以及输出参考点频率值,考虑锁相环的动态作用建立风力发电机组和电网频率之间的端口受控耗散哈密尔顿(PCHD)模型,根据系统平衡方程求得双馈风力发电机组(DFIG)各个状态变量的期望平衡点,然后采用互联和阻尼分配无源控制(IDA-PBC)方法获得转子电压反馈控制律,从而得到DFIG机侧换流器控制和附加阻尼控制器,以改善系统的低频振荡特性,最后以单机无穷大系统和IEEE4机2区域系统为例验证本文所提方法的有效性。     

一种非朗伯表面SFS的快速粘性解算法

针对传统的非朗伯表面明暗恢复形状(SFS)算法存在运行时间长、精度不高的问题,提出了一种粘性意义下的明暗恢复形状快速算法。首先,非朗伯物体表面采用Oren-Nayar模型描述其表面反射属性,摄像机镜头使用适合于实际成像过程的透视投影模式,同时假设光源置于镜头像方主点附近,建立了上述情况下的图像辐照度方程,此方程蕴含着非朗伯表面的高度信息。其次,将辐照度方程转化为Hamilton-Jacobi(H-J)类偏微分方程,运用Legendre变换和最优控制理论得到H-J方程对应的Hamilton函数的控制形式。接着,建立了Hamilton函数的逼近算法,使用非线性规划原理构建Hamilton函数最优问题的等价约束问题,利用得到的最优控制并通过Newton法最终得到了H-J方程的粘性解,该粘性解即是非朗伯物体表面的高度。实验结果表明,提出的算法与典型的基于Lax-Friedrichs方法的算法相比,所需要的运行时间大幅度减少,重构的物体表面的高度平均误差与均方根误差也有较大幅度降低。     

Existence and construction of Hamiltonian paths and cycles on conforming tetrahedral meshes

This paper addresses the existence and construction of Hamiltonian paths and Hamiltonian cycles on conforming tetrahedral meshes. The paths and cycles are constrained to pass from one tetrahedron to the next one through a vertex. For conforming tetrahedral meshes, under certain conditions which are normally satisfied in finite-element computations, we show that there exists a through-vertex Hamiltonian path between any two tetrahedra. The proof is constructive from which an efficient algorithm for computing Hamiltonian paths and cycles can be directly derived.     

Feedback stabilization of nonlinear Hamiltonian control systems

Abstract

Conditions for feedback stabilization of smooth affine nonlinear Hamiltonian systems such as robotic manipulators are given. Some results existing in the literature are unified and extended. Application to nonconservative bilinear systems in elasticity is illustrated.     

Constant and switching gains in semi-active damping of vibrating structures

A limit cycle is the stability boundary for linear and non-linear control systems. Hamiltonian mechanics and power flow control are employed to demonstrate this property of limit cycles. The presentation begins with the concept of linear limit cycles which is extended to non-linear limit cycles. Many examples are used to demonstrate these concepts including linear and non-linear oscillators, power engineering, and an extension to a class of plane differential systems. Power flow control based on Hamiltonian mechanics is shown to be applicable to a large class of non-linear systems. Finally, eigenanalysis and flight stability for linear systems are extended to non-linear systems and is referred to as ‘the power flow principle of stability for non-linear systems’.     

Disturbance rejection of battery/ultracapacitor hybrid energy sources

This paper contributes an active control strategy to reject disturbances in hybrid energy source systems applied in hybrid electric vehicles. The disturbances include persistent disturbances introduced by engine torque ripples compensation, and transient disturbances caused by transient load power demands. The disturbance rejection is achieved via singular perturbation theory. The original system is a Port-Controlled Hamiltonian (PCH) system, and the controller is designed based on interconnection and damping assignment. Experimental results verify the effectiveness of the disturbance rejection control.     

CO分子的光谱理论

给出CO分子精确的量子哈密顿量,建立适合氧原子和碳原子特性的量子算符代数理论;根据该理论,得到第一时间量子态CO分子能量及CO分子的光谱常数。结果表明:第一时间量子态(n=0)CO分子能量值为9.7 eV,与实验测定值完全相符;CO分子振动光谱的光谱常数理论值为0.282 661 618×107 m-1。