Robustness of global asymptotic stability in indirect field-oriented control of induction motors

The influence of the rotor time constant mismatch on the global stability of induction motors under indirect field oriented control (IFOC) is analyzed. A test for global stability is provided, based on necessary and sufficient conditions for the existence of quadratic Lyapunov functions for IFOC drives. This test yields robustness margins with respect to rotor time constant mismatches. A typical example is presented to show that the robustness margins obtained are significantly less conservative than the ones obtained with previously proposed stability criteria.     

异步电机定子电流的内模自适应控制及实现

提出了异步电机定子电流的内模自适应控制及其在转子磁场定向矢量控制中的实现方法。首先,根据内模控制（ＩＭＣ）原理设计异步电机电流调节器,并用矩阵奇异值分析了ＩＭＣ电流调节器的鲁棒性;然后用最小二乘法对模型参数进行辨识;最后将其应用于异步电机转子磁场定向的矢理控制中,通过对电流调节器传递矩阵函数的仿真及用ＤＳＰ实现的异步电机矢量控制运行实验,验证了自适应ＩＭＣ电流调节器的良好性能。     

Robustness margins for indirect field-oriented control of inductionmotors

The influence of the rotor time constant mismatch on the stability of induction motors under indirect field-oriented control is analyzed. The results of De Wu et al. (1996) are generalized. A Lyapunov function which provides a global stability test and allows us to compute robustness margins is given. Different mechanisms fur the loss of stability are detected by means of bifurcation analysis. Robustness margins and design guidelines are derived from these results     

滚动轴承支承下松动-裂纹耦合故障转子系统动力学特性分析

支座松动转子因两端刚度不对称而引发振动异常增大,进而可能导致转子出现裂纹故障,裂纹和松动故障耦合下的转子系统呈现强非线性特性.建立滚动轴承支承的支座松动-弓形裂纹转子动力学模型,研究转速、松动间隙、松动质量及裂纹角等对转子系统非线性动力学响应的影响.考虑非线性Hertz接触力,采用分段线性方程描述支座松动的刚度和阻尼,转子横向裂纹采用呼吸裂纹模型来研究,依据拉格朗日方程建立转子系统动力学方程,采用Runge Kutta法求解方程获得转子振动响应的分岔图、频谱图、轴心轨迹图、Poincaré图等.计算结果表明,当系统转速达到2300rad/s时,松动-裂纹耦合故障系统较仅裂纹系统在1/3分频处有明显的间谐波成分,混沌区域更为宽泛;当裂纹参数恒定时系统随着松动间隙减小会更加稳定;当松动质量ms＞41.25kg时,系统振幅剧增,发生“跳跃”现象.研究工作对松动-裂纹转子系统的故障诊断和健康监测具有重要的工程应用价值.     

锥齿轮传动系统的非线性动力学行为

主要研究了锥齿轮传动转子系统的非线性动力学行为.在滑动轴承或挤压油膜阻尼器中,油膜力是齿轮传动转子系统非线性的一个重要来源,并且与轴承的结构参数、转子的转速和作用力等多个因素有关.首先在刚性转子、齿轮不脱啮等假设条件下,考虑了锥齿轮间的广义位移约束关系,建立在非线性油膜力作用下锥齿轮传动的多转子耦合系统动力学模型.由于油膜力具有强非线性特性,因此采用数值分析方法,结合系统的稳态响应、Poincaré映射和分叉图等多种手段分析系统的动力学行为.通过初步研究得到如下结论:对于不平衡锥齿轮传动的转子系统,在低转速时转子轴心的运动与转速同步;随着转速的增加系统出现2倍周期运动等复杂的分叉现象.这些振动特征可以为这类系统的动力学设计、结构参数优化和运动状态监测等提供必要的理论依据.     

弹性环挤压油膜阻尼器支撑下的柔性转子系统动力学分析

弹性环挤压油膜阻尼器(Elastic ring squeeze film damper, ERSFD)具有良好的支撑作用和减振效果,但由于其结构和流场耦合行为极为复杂,使得已有的物理模型难以完整表现出ERSFD的力学特性.为了进一步探究ERSFD的力学机理,本文借助有限元仿真平台,采用双向流固耦合的计算方法,剖析弹性环与油膜之间的相互作用,获取ERSFD中油膜压力的分布规律.在此基础上,利用最小二乘法进一步拟合出ERSFD等效刚度、等效阻尼与转子轴颈扰动位移的映射关系,并将其分别引入柔性转子系统动力学模型中.通过数值计算研究了ERSFD支撑下柔性转子系统的振动响应,分别给出了不同转速下转子系统的响应分岔图、轴心轨迹等.同时,通过对比分析,进一步揭示了ERSFD所诱发出的转子系统丰富的非线性动力学行为,有助于对ERSFD轴承支撑特性的理解.     

基于硬件滤波电路的无刷直流电机转子位置辨识

反电动势过零检测是无刷直流电机无位置传感器控制中转子位置检测的主要方法之一,为消除PWM因素的影响,需要对转子位置检测电路进行滤波处理。本文采用硬件滤波器对反电动势过零检测电路进行滤波,既要考虑深度滤波带来的相移问题又要兼顾消除噪声的影响,分析滤波器的幅频特性和相频特性,根据反电动势过零检测指标要求设计滤波器参数,并用于无刷直流电机转子位置辨识和无位置传感器控制中。仿真结果和实验结果表明,所采用的滤波器及其参数能较好地检测出转子位置,可以明显提高无位置传感器无刷直流电机驱动系统的控制性能。     

High performance current control of a switched reluctance machine based on a gain-scheduling PI controller

Switched reluctance motor drives are under consideration in various applications requiring speed variation. This is certainly due to their mechanical robustness and low manufacturing cost. However, the non-linear characteristics of the flux and the torque, and the high acoustic noise complicate significantly the controller design. In order to take into account the phenomenon of magnetic saturation and its dependence on the rotor position and the current, a PI controller with variable gains is proposed. This controller compensates the inductance variation and maintains the dynamics of the closed-loop system constant. Simulations and experimental results of the standard PI controller and the gain-scheduling one are discussed. It shows the advantages of the gain adaptation compared to the fixed gains.     

High gain observer based on-line rotor and stator resistances estimation for IMs

One of the main challenging issues in induction motor drives is the lack of knowledge about the actual values of some critical parameters, such as rotor and stator resistances which are subject to large variations during operation. Such problem is difficult to resolve due to the strong interconnection between states and parameters in the nonlinear motor model, besides the unavailability of both rotor flux and load torque. In the spirit to accurately follow the on-line machine variables, this paper focuses on the simultaneous estimation of internal states and time varying parameters. Especially, a new identification scheme for rotor resistance and/or stator resistance is introduced. In the aim of decoupling the unknown electrical parameters, we adopt a mild change of coordinates that allows to easily design a two-stage of high gain observer. The simplicity of presented procedures and the efficiency for real time computation constitute both main features of the proposed approach. Moreover, possible exploitation of our algorithm in the fault detection issue is discussed through a simulation of an abrupt rotor short-circuit.     

Multiphase rotor current observers for current predictive control: A five-phase case study

The use of multiphase drives has gained importance in recent times due to some advantages that they provide over conventional three-phase ones. High performance stator current control can be achieved by means of direct command of voltage source inverter. In this context finite-state model predictive control is a very flexible strategy that has been recently proposed and analyzed. Nevertheless, its implementation must solve the problem of estimating rotor quantities, being the conventional solution a simple backtracking procedure. In this respect, observers appear as an attractive alternative. However, while they have been used with FOC, sensorless drives and for fault detection, they have not been used yet for predictive control of drives as a way to provide rotor values estimates. In this paper the authors propose to incorporate a full-order rotor current observer in a finite-state model predictive controller of a five-phase induction machine. Pole placement design based on Butterworth filters is used. The new estimation scheme and the standard procedure are compared. By means of experimental tests, the differences between both approaches and the benefits of including a rotor observer are illustrated and verified.     

转子-轴承系统响应的分岔与混沌控制分析

给出了对转子-轴承系统的分岔与混沌等复杂动力学行为进行控制的思想．应用washout-filter状态反馈控制方法进行分岔与混沌控制器的设计,用以改进系统转速变化时转轴响应的分岔与混沌特性．通过调整控制器的参数来影响转子系统的动力学行为,控制其运行的稳定性．数值模拟结果表明,随着转子-轴承系统转速的不断提高,系统的动力学行为会发生较大变化,此时应用washout-filter状态反馈控制方法进行分岔与混沌控制,理论上可起到较好的控制效果．     

Ball-disk rotor gyroscope adaptive quick-start technique

Rotating speed is a critical parameter affecting the performance of rotor gyroscopes. Rotor gyroscopes must operate at the rated rotating speed. To shorten the start time of the ball-disk rotor gyroscope, this paper presents a new design of the drive system for a ball-disk rotor gyroscope. The drive system is monitored by a microcontroller. First, the microcontroller generates a sine pulse width modulation signal to drive the permanent magnet rotor. Second, the position of the rotor is detected according to the back electromotive force in the non-energized coil. Third, a piecewise closed-loop control algorithm is implemented to keep the angular acceleration of the rotor within the safe range automatically during the acceleration process and when running at a constant speed. This control algorithm can avoid rotor stalling due to loss of steps. Experimental result shows that with the help of adaptive quick-start technique, the start time of the device can be shortened by up to 36.6%.     

A predictive controller for induction motors using an unknown input observer for online rotor resistance estimation and an update technique for load torque

This paper deals with the design of an output feedback predictive controller for induction motors. The fundamental interest of the proposed controller is the capability of decoupling the mechanical speed and the rotor fluxes, without degradation against the variation of rotor resistance and load torque. Hence, the contribution is to apply two estimation procedures in order to achieve this goal. Namely, an unknown input observer (UIO) is used for the constant time estimation whereas a heuristic solution is exploited for the load torque update. Moreover, rotor flux components are recovered as an unavailable state of the system. Effectiveness of the proposed observers and the performance of the controller are confirmed by simulation results.     

一般Brusselator系统解的稳定性和存在性分析

研究了一般Brusselator系统在Neumann边界条件下解的性质。利用稳定性理论讨论了其常数解的稳定性。以u的扩散系数θ为分歧参数,利用分歧理论分析了由常数解产生的局部和全局分歧情况,给出了局部分歧解存在的充分条件以及分歧解的全局走向。     

PI tuning of five-phase drives with third harmonic injection

The tuning of PI gains for a five-phase induction motor with indirect field oriented control and third harmonic injection is analyzed. Third harmonic injection allows to increase the output torque density. A study of the local linearized system shows that rotor time constant detuning and drive load play a crucial role in transient behavior. Also, it is shown that the PI tuning has to be obtained as a balance between conflicting interests. Some measures of the transient performance are presented and used to derive guidelines for setting the PI controller. The proposed guidelines involve a numerical procedure applicable to any drive with third harmonic injection, with either constant or variable ratio to the fundamental component. The results are illustrated by a set of simulation experiments.     

基于动态模式的转子系统故障诊断

以Jeffcott转子系统基础松动-碰摩耦合故障为例,研宄动态模式的转子系统故障诊断方法.首先,将转子系统正常和故障时的未知系统动态定义为不同的动态模式,对其进行学习,将学到的知识以常数神经网络权值的形式存储,并建立动态模式库;然后将当前被监测转子系统与动态模式库中的动态模式进行比较,根据动态模式的相似性定义,依据最小误差原则快速判断转子系统与已学过的哪种动态模式相似,实现故障的快速检测与分离.仿真结果验证了算法的有效性.     

Disturbance-generated bifurcations in a simple adaptive system: Simulation evidence

We present complete characterization based on computer simulation of the possible dynamics exhibited by an adaptive control system where the (first order) plant with a single unknown pole has constant disturbance at the input. The adaptive system is taken from the current adaptive control systems literature. Here we show that the system in fact undergoes bifurcations and exhibits rich dynamics. As the constant disturbance is varied, the system undergoes saddle-node bifurcation, (subcritical) Hopf bifurcation, and a saddle connection bifurcation. The last bifurcation means that the system acquires a homoclinic orbit for a specific disturbance. While the first two bifurcations are local, the presence of the homoclinic orbit has the potential, when periodically disturbed, to generate nonlocal complicated behavior. This latter behavior is often referred to as ‘horseshoe chaos’.     

具有参数和负载不确定性的感应电机自适应反步控制

基于磁场定向坐标系下的感应电机模型,采用自适应反步方法设计控制器,通过选择适当的Lyapunov函数来保证整个系统的稳定性．进而逐步导出控制律和参数自适应律．该方法可在电机参数发生变化和出现负载扰动的情况下,实现转速和转子磁链的渐近跟踪．仿真结果证实了该方法的有效性．     

Thermal mechanics of a contact sensor used in hard disk drives

A typical thermal-contact sensor (TCS) used in hard-disk drives was investigated by the simulation. Analytical solution to solve temperature variation of sensor due to frictional heat was built to estimate the sensor temperature rise under variable heating power and interference height between the head and disk. To accurately and systematically qualify sensor-temperature distribution and resistance variation under certain variable conditions and sensor time constant, head housing a TCS was modeled by ANSYS commercial software, and thermal-mechanics of TCS coupled with air bearing dynamics was simulated. Simulated results indicated that a TCS with a proper size of 1 μm or less had a maximum resistance variation on friction induced heating to generate a maximum TCS signal output. The sensor-heating maximum protrusion was less that 0.1 nm, and time constant of TCS is about 0.125 μs and its response frequency is about 8 MHz. With a highly accurate measurement system, TCS can detect out asperities of tens of nanometers or less. These results will be helpful in developing and designing thermal-contact sensors for use in hard-disk drives.     

多机传动机械系统的同步控制

本文提出通过磁场定向控制分别控制多个感应电动机跟踪同一个指令性速度的多机驱动机械系统的同步控制方案,通过建立全维转子状态估计器,辩识感应电动机的转子速度,定子和转子电阻,瞬时外负载,根据外负载辩识结果与速度ＰＩＤ控制器确定感应电动机的转矩电流,实现感应电动机的无速度传感器控制,计算机仿真结果表明了该控制方案的有效性。