基于转子电流的双馈风机模糊控制无速度传感器设计

本文针对传统PI控制器调节速度慢的缺点,设计了基于转子电流的双馈风机模糊控制无速度传感器。该设计将参数自整定模糊PI控制技术引入转子速度估测模型中,以提高转子观测器的跟踪效果和动态特性。利用Matlab/Simulink搭建了仿真模型,仿真结果表明:基于转子电流的双馈风机模糊控制无速度传感器能够快速准确地估测转子速度和位置角度,具有良好的动态特性,对电机参数的变化具有一定的抗干扰能力。     

基于自适应状态观测器的异步电机无速度传感器矢量控制系统

异步电机无速度传感器矢量控制系统是目前研究的热点,本文采用一种闭环磁链观测器,即自适应状态观测器对转子磁链进行观测,与传统开环电压、电流模型相比,观测效果更好。在转子磁链观测的基础上,采用PI型自适应律,对转速进行了辨识。最后,通过Matlab仿真验证了本文给出的异步电机无速度传感器矢量控制系统的可行性,仿真结果表明该系统具有较好的动、静态性能,并具有一定的抗干扰能力。     

基于MRAS的异步电机无速度传感器的矢量控制

由于电机定转子参数的变化,利用一般的转子磁链对转速进行估算,将导致不能得到准确的结果。这里采用积分型转子磁链的参考和可调模型构建出一个基于MRAS的异步电机无速度传感器的矢量控制模型。该模型提高了矢量控制系统的动态性能并利用MATLAB,sIMULINK进行了异步电机无速度传感器矢量控制系统的仿真,验证了文中所采用的模型参考自适应的速度估算方法的可行性以及对参数误差的鲁棒性。     

民航雷达电机无速度传感器矢量控制设计

针对民航雷达电机无速度传感器矢量控制系统进行了研究,在(/dq)坐标系下建立异步电机的数学模型,利用电动机定子电压方程和电流方程,采用模型参考自适应辨识算法,建立了一个基于转子磁场定向的异步电机无速度传感器矢量控制系统,并利用Mat Lab/Simulink软件对该控制系统进行仿真。     

基于矢量控制的异步电机速度检测方法的研究

基于矢量控制理论设计的变频器控制系统性能的优劣,取决于系统对电流和速度的控制,其中主要包括输出电流的检测和速度反馈信号的检测。在本文中,针对有速度传感器系统和无速度传感器系统两种情况,对异步电机速度反馈信号检测的方法进行探讨。     

基于MRAS的异步电机无速度传感器矢量控制

异步电机无速度传感器矢量控制系统中的速度辨识方法是目前研究的热点,其中MRAS由于其原理简单、实用性较强等优点,在交流调速系统中得到了广泛应用。本文采用改进的电压型转子磁链估算模型,避免了由纯积分环节造成的积分漂移等问题,采用可变PI型自适应律,结构简单且具有较好的辨识效果,最后给出了转子磁场定向的无速度传感器矢量控制系统的实现,仿真结果表明该系统具有良好的动静态性能,且具有一定的抗干扰能力。     

无传感器交流传动技术的展望

在电机轴上无机械速度传感器的可控交流电机驱动，由于其低廉的价格和较高的可靠性，一直备受关注。为了取代传感器，它通过测量定子电流和电机端电压得到转子速度信息。矢量控制传动需要估计定子或转子磁通基波的大小和空间位置。为此需要使用开环估计器或闭环观测器，它们在准确性、鲁棒性以及对模型参数变化的敏感性等性能上均不相同。通过信号注入即利用电机的各向异性，可以获得零速范围附近的动态性能和稳态速度精度。本文使用复杂空间矢量的信号流程图来形象地描述交流电机无传感器的控制系统。     

基于MRAS的无速度传感器矢量控制的研究

利用异步电动机定子电压、电流易于检测的特点,运用模型参考自适应（MRAS）的算法对电动机的转速进行辨识,以MATLAB/Simulink里面的Simpower工具箱为基础,搭建了异步电机无速度传感器矢量控制系统的仿真模型。结果表明,本系统设计方法可行、具有良好的速度响应和动静态性能。     

基于模型参考自适应滑模观测器的DFIG无速度传感器控制

论文为双馈感应发电机提出一种基于模型参考自适应滑模观测器观测转子电流的无速度传感器控制策略.以电机本体作为参考模型,在双馈感应发电机d-q坐标模型的基础上构建转子电流估算模型.依据实转子实际电流和转子估算的电流之间的偏差,通过模型参考自适应滑模观测器来估计电机转子位置和转速.该控制策略对电机参数变化具有很强的鲁棒性和快速性.最后搭建了双馈风力发电仿真平台,对所提的控制策略进行验证.仿真结果验证了所提方案可行性和正确性.     

无轴承异步电机无速度传感器控制

为解决无轴承异步电机运行中转速辨识问题,提出了一种可以同时在线估计转子电阻和转速的方法。该方法首先通过电压型转子磁链模型估计出转子磁链,然后根据静止坐标系下的无轴承异步电机模型和电压型转子磁链模型推出包含转子电阻和转速的表达式,再将这两个表达式看作一个二元一次方程组并求解,最终得到转子电阻跟转速的解析表达式。最后应用这种转速估计方法构建无轴承异步电机无速度传感器控制系统,并开展仿真研究。仿真结果表明:所提方法能够实现无轴承异步电机转子电阻和转速的准确估计,并保证无轴承异步电机的稳定悬浮运行。     

Sensorless speed measurement using current harmonic spectralestimation in induction machine drives

This paper proposes a sensorless speed measurement scheme that improves the performance of transducerless induction machine drives, especially for low-frequency operation. Speed-related harmonics that arise from rotor slotting and eccentricity are analyzed using digital signal processing. These current harmonics exist at any nonzero speed and are independent of time-varying parameters, such as stator winding resistance. A spectral estimation technique combines multiple current harmonics to determine the rotor speed with more accuracy and less sensitivity to noise than analog filtering methods or the fast Fourier transform. An on-line initialization routine determines machine-specific parameters required for slot harmonic calculations. This speed detector, which has been verified at frequencies as low as 1 Hz, can provide robust, parameter-independent information for parameter tuning or as an input to a sensorless flux observer for a field-oriented drive. The performance of the algorithm is demonstrated over a wide range of inverter frequencies and load conditions     

A self-tuning closed-loop flux observer for sensorless torquecontrol of standard induction machines

This paper proposes a self-tuning closed-loop flux observer, which provides field-oriented torque control for induction machines without a tachometer. The proposed algorithm combines the best features of harmonic detection and stator voltage integration through the use of a new tuning scheme. The observer accuracy and robustness is augmented by a parameter-independent accurate-speed detector, which analyzes magnetic saliency harmonics in the stator current. The harmonic-detection scheme provides accurate rotor-speed updates during steady-state operation down to 1-Hz source frequency. This additional speed information is used to tune the rotor-resistance parameter of the observer. The tuned observer exhibits improved dynamic performance, accurate steady-state speed control and an extended range of control near zero speed. The algorithm requires no special machine modifications and can be implemented on most existing low- and medium-performance drives. The closed-loop nature of the flux observer, combined with the harmonic-detection scheme, provides flux and speed error feedback, which significantly increases the robustness of sensorless control across the entire speed range     

Sensorless control of induction Machines at zero and low frequency using zero sequence currents

This paper considers both flux and rotor position estimations for sensorless control of delta-connected cage induction machines (IMs) at low and zero frequency operation. The variation of leakage inductance due to either saturation or rotor slotting is tracked by measuring the derivative of the zero sequence current in response to the application of appropriate voltage test vectors. The method requires only a single extra sensor. It requires access to machine phase windings and is appropriate for integrated-type induction motor drives. Both a closed-slot and an open-slot machine is used to demonstrate rotor flux and rotor position tracking, respectively. Experimental results are presented showing sensorless torque control and sensorless speed and position control at low and zero frequencies.     

Class-F power amplifiers with maximally flat waveforms

Class-F power amplifiers (PA's) employ harmonic-frequency resonators to shape their drain or collector waveforms to improve efficiency. Generally, the output network must present the drain with either an open or short circuit at the harmonic frequencies. At VHF and higher frequencies, the drain capacitance, lead inductance, lead length, and dispersion make implementation of reasonably ideal tuned circuits difficult. However it is possible to control the impedances at a finite number of harmonics. This note first derives the basic relationships among the Fourier coefficients of the waveforms and the performance of the amplifier. Fourier coefficients for maximally flat waveforms are then derived for inclusion of up to the fifth harmonic. Amplifier performance is then tabulated as a function of which harmonics are included in the voltage and current waveforms. Efficiency increases from 50% of class A toward 100% as harmonics are added. Power-output capability increases by up to 27%     

Hybrid rotor position observer for wide speed-range sensorless PM motor drives including zero speed

This paper addresses the problem of wide speed-range sensorless control of a surface-mount permanent-magnet (SMPM) machine including zero-speed operation. A hybrid structure integrating a flux observer and signal-injection techniques is proposed, which results in a rotor position signal independent of motor parameters at low and zero speed. Although the SMPM machine typically has a very low geometric saliency, the injection technique is effective in tracking the saturation-induced saliency produced by the stator flux. Experimental results are presented showing an excellent performance for both the sensorless speed and position control using an off-the-shelf SMPM machine.     

Comparative analysis of experimental performance and stability of sensorless induction motor drives

This paper compares the experimental performance of three flux and speed observers for speed-sensorless induction motor drives and discusses the cause of their differences. The small signal analysis using the linearized model is carried out to analyze stability. Three methods are generally accepted to be representative candidates for high sensorless performance, namely: 1) rotor-flux model reference adaptive system (MRAS); 2) torque-current MRAS; and 3) adaptive nonlinear flux observer. Many other sensorless methods improved these methods. The paper discusses baseline conditions for the experiments and the stability analysis, which include matched load inertia, specified speed estimator dynamics, and sensorless operation within a speed control loop. For the comparison tests in the paper, the speed estimation dynamics of the methods are the same; this is important for parameter sensitivity. The paper concentrates on the low-speed performance, and all results shown are under sensorless speed control.     

Current-mode control for sensorless BDCM drive with intelligent commutation tuning

The winding current response speed and the adequate commutation significantly affect the control performance of a sensorless brushless dc motor (BDCM) drive. In this paper, the studies about these two issues to enhance the performance of BDCM drive are made. First, the sensorless inverter-fed BDCM drive with a proposed current command generation scheme is established. An intelligent commutation instant tuning technique is developed to pursue better motor torque generating characteristics. For achieving this goal, the motor drawn line current minimization is employed as the performance index in making the commutation tuning. After generating the current command with adequate commutation, a robust current-mode controller is further developed and applied to greatly speed up the square wave current tracking response and the response is rather insensitive to the machine parameter and back electromotive force (back-EMF) changes. In Addition, a simple starting method and a speed estimation approach are also proposed. Some experimental results are provided to demonstrate the validity of the proposed control method.     

Sensorless Position and Speed Control of Induction Motors Using High-Frequency Injection and Without Offline Precommissioning

This paper addresses the sensorless speed and position control of induction motors using high-frequency injection at zero and low frequencies. A novel algorithm is presented which allows the rejection of saturation and nonlinear inverter effects without the need for an offline precommissioning process. The method is based on a set of synchronous filters to identify the disturbance waveforms and a memory algorithm that refines the quality of the disturbance waveforms as the motor's operational history is increased. The algorithm is entirely sensorless. Experimental results show sensorless low-frequency operation with and without the memory algorithm.     

无速度传感器感应电机控制系统的现状与展望

新技术的发展给电机控制行业带来新的发展机遇。从电机控制器、无速度传感器技术方面,介绍了国内外无速度传感器感应电机控制系统中这两个领域内的研究现状及发展趋势。回顾了DSP处理器的发展历程,介绍了DSP的发展现状,从设计和应用角度分析了DSP的特点,介绍了DSP的发展前景;分析了无速度传感器技术的研究现状,指出电机低速下速度估计性能差及低频范围稳定运行问题是目前无速度传感器技术的研究热点,并提出了相应的解决方法。     

A new scheme for speed-sensorless control of induction motor

Various control algorithms have been proposed for the speed-sensorless control of an induction motor. These sensorless algorithms are mainly based on the speed feedback with the flux and speed estimations. This paper proposes a new scheme for the speed-sensorless control of an induction motor. The proposed scheme is based on the current estimation without the flux and speed estimations, in which the controlled stator voltage is applied to the induction motor so that the difference between stator currents of the mathematical model and motor may be forced to decay to zero. The performance of the proposed scheme is verified through simulation and experiment.