一种改进型异步电机直接转矩控制系统研究

在传统无速度传感器异步电机直接转矩控制系统基础之上进行了改进研究,将变结构控制和无速度传感器技术引入进来,设计电机定子磁链控制器和电磁转矩控制器,并应用Lyapunov第二方法推导出转子转速和定子电阻自适应辨识律.通过Matlab/Simulink的仿真,验证了改进后的系统比传统系统具有更好的动静态性能,并具有良好的鲁棒性.     

基于DSP异步电机无速度传感器直接转矩控制

基于模型参考自适应系统原理(Model Reference Self-Adapt System,简称MRAS)设计了一种新型的速度磁链自适应观测器,它以定子电流和定子磁链为状态变量,把磁链观测和速度辨识结合在一起,可以将定子磁链观测值直接应用于直接转矩控制算法中.定义了李亚普诺夫函数,根据其稳定性理论确定了速度自适应律.以TMS320F2812为核心构成控制器,实现异步电机无速度传感器直接转矩控制系统.实验结果证明,该系统具有较好的定子磁链和转速观测精度,能改善低速时磁链畸变程度和运行特性.     

基于MRAS和FNN的异步电动机无速度传感器直接转矩控制

针对传统直接转矩控制系统中磁链和转矩存在较大的脉动,采用基于模糊神经网络(FNN)控制器的预期电压矢量调制方案.速度传感器安装不方便、成本高,磁链观测对电阻的依赖性强,尤其是在电机低速运行时,应用模型参考自适应控制策略(MRAS)设计速度、电阻自适应定子磁链观测器,以定子电流和定子磁链为状态变量,利用Popov超稳定性理论得到转子转速和转子电阻的自适应律.建立了异步电动机无速度传感器直接转矩控制系统的Matlab/Simulink仿真模型,仿真结果表明系统脉动较小,提高了定子磁链和转速的观测精度.     

基于滑模变结构的PMSM直接转矩控制

分析了永磁同步电机(PMSM)数学模型,设计了一种新颖的基于空间矢量脉宽调制技术的直接转矩控制(SVM-DTC)系统。利用两个PI控制器分别调节磁链和转矩实现对电机空间矢量中转矩和磁链两分量的解耦,同时采用基于转子位置和定子电流的定子磁链估算方法观测定子磁链,并设计滑模变结构无速度传感器来估算转子位置。仿真结果表明,所提出的方法能有效地估算定子磁链与转速,减小电磁转矩和定子磁链脉动,从而使系统具有较好的动、静性能。     

改进蚁群算法优化神经网络速度辨识器的研究与应用

对基本蚁群算法进行了改进以提高其全局寻优速度,并用此改进型的蚁群算法来优化神经网络,再将该神经网络应用于直接转矩控制系统当中,实现对转速的观测,最终实现无速度传感器的直接转矩控制。仿真研究表明,改进的蚁群算法具有优良的全局优化性能,且收敛速度较快,应用其优化的神经网络在直接转矩控制系统中能较准确地辨识出系统转速,从而可以替代传统的速度传感器,实现无速度传感器直接转矩控制。     

一种新颖的永磁同步电动机无位置传感器技术

无位置传感器技术是永磁同步电动机调速系统的一个发展方向.本文剖析了已有的两种典型直接估算方法,提出了一种新颖的无位置传感器技术.通过分别计算出定子磁链矢量角位移与转矩角,将后者从前者中减去得到转子磁链矢量的角位移进而得到转子速度信号,并采用改进积分器取代传统的积分器.该技术能有效地改善磁链原点漂移,提高直接转矩控制系统的磁链角位移与转速的求解准确度.仿真及实验研究结果表明,采用这种无位置传感器技术的永磁同步电动机调速系统,具有良好的调速控制性能.     

具有效率优化计算的异步电动机自抗扰与滑模直接转矩控制

为了克服异步电动机直接转矩控制中转矩和电流脉动大等缺点,设计改进的自抗扰速度控制器取代传统的比例积分(PI)控制器。根据异步电动机的数学模型以及滑模变结构控制理论设计了一种基于转矩误差和磁链平方误差的新型滑模控制器。考虑电机运行过程中负载转矩未知问题,设计了一种基于Super-twisting算法的负载转矩观测器。Super-twisting定子磁链观测器的应用提高了观测精确度。通过效率优化计算得出稳态时最优定子磁链,并将其引入调速系统。仿真试验结果表明,该控制策略有效地减小了转矩和电流脉动,并且对外部扰动具有较强抑制作用,同时能够降低电机运行损耗,具有良好的动态和稳态性能。     

无速度传感器直接转矩控制方案的设计和仿真

直接转矩控制是一种高性能的交流传动控制策略,无速度传感器控制的研究代表了直接转矩控制系统的一个发展方向.在直接转矩控制理论基础上,推导出一种基于定子磁链矢量增量来确定定子参考电压矢量的新型无速度传感器直接转矩控制方案.该方案还能对转矩和磁链实现良好的控制功能.计算机仿真结果证明了方案的可行性.     

基于变参数PI和模糊控制的直接转矩控制

针对传统永磁同步电机(PMSM)直接转矩控制系统中存在定子磁链和电磁转矩脉动的缺点,提出一种基于变参数PI和模糊控制的直接转矩控制方法,将传统直接转矩控制系统中PI速度调节器和滞环比较器分别用变参数PI速度控制器和模糊控制器代替.介绍了变参数PI和模糊控制的原理和设计方法,最后构建了改进后系统控制框图,并进行了实验验证...     

感应电机无速度传感器控制系统的仿真研究

针对一种基于扩展卡尔曼滤波器(EKF)的感应电动机无速度传感器直接转矩控制系统负载转矩和转速同时估计进行仿真。在直接转矩控制的基础上,通过定子侧可测量的电压、电流值,转速和转矩作为扩展状态量,构建一种无速度传感器的感应电机转速、磁链状态观测器,估算感应电机的负载转矩和转速。该方法能准确估算电机的真实状况,并对负载扰动、电机参数变化具有较强的鲁棒性。仿真结果表明,无速度传感器系统具有较强的动态控制性能,该系统具有抗干扰能力强、超调量小、响应快。     

采用定子电阻辨识和无速度传感器的异步电机直接转矩控制模糊系统

为解决异步电动机直接转矩控制(direct torque control,DTC)中低速运行时定子电阻变化对系统性能影响较大的问题,提出了一种基于定子电阻辨识和无速度传感器的异步电机直接转矩控制模糊系统。其中定子电阻采用模糊神经网络进行辨识;电机转速采用基于转子磁链的模型参考自适应系统(model reference adaptive sys-tem,MRAS)法进行估计;同时采用三输入单输出的模糊控制器调节脉冲宽度调制(pulse width modulation,PWM)信号占空比的异步电动机直接转矩控制的策略,三输入变量为转矩误差、磁链幅值误差和磁通角。此策略即在传统异步电动机直接转矩控制的基础上,用模糊控制器代替传统DTC中的滞环比较器和空间电压矢量状态选择器来细分控制规则,最后控制逆变器的开关,以减小低速时转矩和磁链脉动,提高系统转矩响应速度。仿真结果表明该系统可减小转矩和磁链脉动,提高系统的鲁棒性和自适应性,改善系统的动、静态品质。     

Robust direct torque and flux control of adjustable speed sensorless induction machine drive based on space vector modulation using a PI predictive controller

A Direct torque and flux control design for a sensorless induction motor, following a Lyapunov-based stator flux observer is presented. In this control scheme, the torque error signal and the amplitude of the stator flux reference vector are delivered to a PI predictive controller. The predictive controller also uses information on the amplitude and position of the actual stator flux vector and measured stator currents to determine the voltage command vector for space vector modulation inverter. In addition, a conventional PI speed controller is used to generate the torque reference signal. Using the fifth order model of the three-phase induction machines in a stationary two axes reference frame, a nonlinear stator flux observer is developed in order to estimate the rotor speed, rotor and stator resistances simultaneously. The stability of this observer is proved by Lyapunov theory. It is shown that if the persistancy of excitation condition is satisfied, the estimated quantities converge to their real values. The effectiveness of the proposed control scheme is verified by computer simulation and experimental results.     

一种新型的基于观测器的无速度传感器感应电动机定子电阻辨识方案

建立了一种新型的全阶自适应状态观测器,提出了基于观测器的速度和定子电阻辨识方案.应用Lyapunov稳定性理论,经过严格推导得出了速度辨识自适应律;通过对两个双线性矩阵不等式的求解得到状态观测器的增益矩阵,从而克服了现有采用极点配置的自适应速度观测器存在不稳定区域的问题.在此基础上,由Lyapunov稳定性条件,在保持观测器增益不变的情况下,得到观测器的定子电阻辨识算法;通过将定子电阻的辨识值反馈,减小了定子电阻变化对系统性能的影响.在Matlab/Simulink环境下,对基于自适应观测器的无速度传感器感应电机直接转矩控制进行了仿真,并以TMS320F240为控制核心构建了感应电动机直接转矩控制系统,完成了速度辨识和定子电阻辨识实验.仿真和实验结果表明本文给出的自适应观测器在全速范围内具有良好的稳态和动态性能.     

A generalized method of controlled voltage source-fed induction motor vector control using the observer theory

Vector control of induction motors is widely used for industrial applications. On-line parameter identification and speed sensorless control are being studied actively. A representative method for these problems is the application of an adaptive full-order observer. The rotor flux for vector control is estimated by a full-order observer and machine parameters, or the rotor speed is determined by an adaptive algorithm. In this paper, a new vector control scheme with parameter identification is proposed. This method is based on the adaptive full-order observer. However, the observed currents which are usually estimated in the voltage model are considered as command currents and the voltage model is used for the current controller. As a result, the proposed system is simpler than the conventional adaptive full-order observer system. Since the proposed system is composed of an induction motor model in a synchronously rotating reference frame, the well-known slip frequency control block is contained. The arrangement of the poles which are related to the torque transfer function is discussed. A linear model is derived taking into account the effects of the change of the stator and rotor resistances. The trajectories of poles and zeros of the torque transfer function are computed and discussed for various system parameters. Identification of stator and rotor resistances is confirmed by simulation using a nonlinear system model. The proposed idea is applied to a speed sensorless system; this system has a similar configuration to those of existing systems under some assumptions. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 119(4): 66–76, 1997     

Braking Scheme for Vector-Controlled Induction Motor Drives Equipped With Diode Rectifier Without Braking Resistor

This paper deals with sensorless vector control of pulsewidth-modulated inverter-fed induction motor drives equipped with a three-phase diode rectifier. An electronically controlled braking resistor across the dc link is not used. Instead, the power regenerated during braking is dissipated in the motor while a dc-link overvoltage controller limits the braking torque. Losses in the motor are increased by an optimum flux-braking controller, maximizing either the stator voltage or the stator current depending on the speed. Below the rated speed, the braking times are comparable to those achieved using a braking resistor. The proposed braking scheme is very simple and causes no additional torque ripple. Experimental results obtained using a 2.2-kW induction motor drive show that the proposed scheme works well.     

Speed-sensorless direct torque control of induction motors using anadaptive flux observer

This paper presents a new sensorless induction motor drive. The drive uses an adaptive flux observer for speed estimation and the discrete-time direct torque control technique for torque and stator flux control. The adaptive flux observer uses a mechanical model to improve the behavior during speed transients. The estimated stator flux of the adaptive observer is used in the discrete-time direct torque control method to provide fast torque response combined with torque-ripple-free operation over the whole speed range. The sensorless drive system is capable of working from very low speed to high speed and exhibits good dynamic and steady-state performance. The steady-state and dynamic performance of the proposed sensorless drive using simulation and experimental results are demonstrated     

基于MRAS理论的无速度传感器直接转矩控制调速系统

在MRAS理论基础上讨论了三种转速观测法,并将其中既能实现电机转速辨识又能实现定子电阻辨识的交互式模型参考自适应方法应用于异步电机无速度传感器直接转矩控制中.该方法能较好地解决电机参数变化对调速精度和系统稳定性影响的问题,仿真结果证明了该方案的有效性.     

基于新型磁链观测模型的矢量控制系统研究

在异步电动机数学模型的基础上,介绍了一种改进的定子磁链观测方法,并在此基础上设计了转速估算器.磁链观测器和速度估算器结合起来应用于无速度传感器的矢量控制系统.通过Matlab仿真试验,得到转速、转矩、定子电流及其磁链等的仿真波形.仿真结果验证了该控制方法具有较好的动态响应和较强的鲁棒性.     

Lower speed range drive for sensorless vector controlled induction machines with stator voltage offset compensation method

The vector control method is widely used for induction machine drives. Recently, sensorless vector control for induction machines has been investigated and proposed. The speed range for the drives is limited to about 1:100 in industry. The main reason for this limitation is the inaccuracy of stator voltage measurement. The lower the rotor speed is, the lower the stator voltage. Therefore, it is difficult to detect the stator voltage accurately in the lower speed region, and difficult to control motor speed and motor torque precisely. This paper presents a method of improving the lower speed performance of sensorless vector controlled induction machine drives using offset compensation of stator voltage. The offset is compensated by using the fluctuation of the estimated rotor flux. The validity of the proposed method is verified by experimentation. © 2000 Scripta Technica, Electr Eng Jpn, 133(1): 79–86, 2000