Dual-Plane Vector Control of a Five-Phase Induction Machine for an Improved Flux Pattern

A technique to improve the flux pattern within a five-phase induction machine is presented. The technique is developed through dual-plane vector control, with synchronized fluxes. By vector space decomposition, an analytical model and vector control of the machine are accomplished in two orthogonal vector planes,d₁-q₁ and d_s-q_s . The magnitude and rotating speed of the associated fluxes (fundamental and third harmonic) can be independently controlled in each vector plane. Synchronization control locks the relative position between the two fluxes. The resultant air-gap flux density is fully controlled, preventing iron saturation. This feature is especially important in reshaping the flux and back EMF waveform of the machine. A quasi-trapezoidal air-gap flux density distribution is achieved for better iron utilization and higher torque density. It is confirmed that compared with sinusoidal fluxing, the quasi-trapezoidal flux pattern will not lead to an oversized power inverter when improving machine torque density. The basic understanding and control scheme can be extended to a multiphase induction machine with a phase number greater than five.     

Suppression of saturation saliency effects for the sensorlessposition control of induction motor drives under loaded conditions

This paper presents an automated commissioning procedure used for the elimination of the saturation saliency effects in the sensorless position control of field-orientated cage induction motor drives. The position control itself is based on extracting a rotor position estimate from a high-frequency signal injection interacting with natural or engineered rotor position saliencies within the machine. The paper shows that this estimate cannot be robustly or accurately obtained if saturation saliencies are present. The paper introduces a method for suppressing the effects of the saturation saliency through information gained in a prior commissioning procedure. The effectiveness of the procedure is demonstrated through experimental results showing both good suppression of the saturation harmonics and true sensorless position control under high load torques     

Modeling and simulation of induction machine vector control withrotor resistance identification

This paper shows that it is possible to use available commercial software to model and simulate a vector-controlled induction machine system. The components of a typical vector control system are introduced and methods given for incorporating these in the MATLAB/SIMULINK software package. The identification of rotor resistance is important in vector control, if high-performance torque control is needed, and modeling of the extended Kalman filter (EKF) algorithm for parameter identification is discussed. It is certainly advisable, when feasible, to precede implementation of new algorithms, whether for control or identification purposes, with an extensive simulation phase. Additionally, a technique for generating pulse-width modulation (PWM) phase commands to extend machine operation to higher speeds before field weakening occurs is simulated in a vector-controlled induction machine, driven by a PWM inverter. This demonstrates the versatility of the vector-controlled induction machine system model     

电励磁同步电机参数辨识方法综述

同步电机数学模型及参数对电力系统分析计算、电机设计、电机运行及控制等都具有重要意义。如何获得精确地同步电机参数已经成为一个重要的研究方向,国内外学者主要从设计计算和测量方法两方面进行研究。频域辨识主要采用同步电机的傅里叶变换形式的数学模型进行分析,而时域辨识的数学模型则采用同步电机瞬态过程的状态方程。本文首先描述了同步...     

IPM synchronous machine drive response to a single-phase open circuit fault

This paper investigates the steady-state and dynamic response of an interior permanent magnet (IPM) synchronous machine drive to a single-phase open-circuit fault. This fault results in rotational electromagnetic asymmetry on both the stator and rotor, making it difficult to analyze using classical dq-transformation techniques. This paper presents a new dq synchronous-frame machine model that is capable of handling this highly asymmetrical fault condition, including the effects of q axis magnetic saturation. Fault responses with two alternative post-fault control strategies are investigated: (1) opening all of the inverter switches so that the machine behaves as an uncontrolled generator (UCG), with the two unfaulted phases connected to the inverter DC link via the antiparallel diodes; and (2) shorting the two remaining unfaulted phases together using the inverter switches. Results of this investigation show that the fault response is generally more benign using the UCG control strategy, with significantly lower phase currents and pulsating torque than corresponding values delivered using the phase-shorting strategy.     

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.     

Decoupling control of induction motor drives

The decoupling control of induction machines is investigated. Three different schemes for decoupling-control methods based on stator flux, airgap flux, and rotor flux field regulation are developed. The control dynamics of each scheme are outlined and studied. Simulation results are presented to verify that these schemes provide decoupling control with excellent dynamic behavior. The transient and steady-state relationships between slip frequency and torque, under constant stator flux, airgap flux, and rotor flux operations, are simulated and compared. The sensitivity characteristics of the three methods of flux-control, machine fed by impressed currents and voltages, are also compared and studied. A prototype torque-drive system is implemented to demonstrate the decoupling control of a squirrel-cage induction machine     

Transient simulation of lamination material properties inelectrical machines

All zero-speed-sensorless control schemes of electrical drives use a high-frequency excitation of the machine to determine local differences of the leakage inductances and to estimate the flux or the rotor position. One of these methods detects the local differences by evaluating the change of the stator current space phasor due to stator voltage test phasors. To get a deeper insight into the transient electric behavior of the machine, it is necessary to take into account also dynamic processes in the lamination material. To achieve this, a model has been developed to simulate the magnetization process in an induction motor fed by a voltage-source inverter. The proposed model calculates the current change due to voltage pulses taking into account the hysteresis as well as eddy currents. In order to limit the computation time, the model has to be kept simple. Measurements on an inverter-fed induction machine as well as on a stator lamination are presented. to verify the applicability of the model     

DC machine models for SPICE2 simulation

A four-level computer model is proposed for DC machine simulation using SPICE2 to meet different simulation requirements. The most complex model takes account of magnetic saturation, armature reaction, current dependence of winding circuit parameters, and eddy current effects. The models have been developed to enable designers to simulate the static and dynamic characteristics of a complete converter drive system including the DC machine more simply, practically, and reliably in one simulation run. Some simulations have been investigated to demonstrate the benefits of the SPICE2 machine models     

High-performance robust motion control of machine tools: an adaptive robust control approach and comparative experiments

This paper studies the high-performance robust motion control of machine tools. The newly proposed adaptive robust control (ARC) is applied to make the resulting closed-loop system robust to model uncertainties, instead of the disturbance observer (DOB) design previously tested by many researchers. Compared to DOB, the proposed ARC has a better tracking performance and transient in the presence of discontinuous disturbances, such as Coulomb friction, and it is of a lower order. As a result, time-consuming and costly rigorous friction identification and compensation is alleviated, and overall tracking performance is improved. The ARC design can also handle large parameter variations and is flexible in introducing extra nonlinear robust control terms and parameter adaptations to further improve the transient response and tracking performance. An anti-integration windup mechanism is inherently built in the ARC and, thus, the problem of control saturation is alleviated. Extensive comparative experimental tests are performed, and the results show the improved performance of the proposed ARC.     

基于社会监控视频的雨量反演

针对利用机器视觉算法估算雨量低准确率的问题,提出基于社会监控视频的雨量反演算法。首先利用降雨分类网络剔除无雨视频;其次引入交替方向乘子法(alternating direction method of multipliers, ADMM)提取降雨视频的前景信息,并通过语义分割和背景差分方法选取感兴趣区域(region of interest, ROI);然后构建以灰度变化和饱和度为特征的高斯混合模型(Gaussian mixture model, GMM)筛选ROI区域内的雨滴;最后依据透视成像关系计算雨滴尺寸,使用气象学Gamma模型反演降雨量。实验结果表明,本文降雨分类方法的准确率在MWD (multi-class weather dataset)到达91.3%,在真实的数据集到达77.0%,雨量估算结果相比于现有方法更为准确。     

Optimal torque control of permanent magnet synchronous machines using magnetic equivalent circuits

In recent years, permanent magnet synchronous machines (PSMs) are often designed in a mechatronic way to obtain e.g. special torque characteristics at zero currents or maximum efficiency. These designs are often characterized by a pronounced magnetic saturation and non-sinusoidal properties. This paper describes the optimal torque control of such PSMs utilizing a magnetic equivalent circuit (MEC) model. In contrast to approaches based on fundamental wave models (dq0-models), which utilize the Blondel–Park transformation and typically consider saturation and non-sinusoidal characteristics only in a heuristic way, MEC models allow to systematically account for these effects. Given the MEC model, optimal values for the coil currents are obtained from a constrained, nonlinear optimization problem, which can be efficiently solved by exploiting the special mathematical structure of the model. The results of the optimization are used in a flatness-based torque control strategy. The performance and practical feasibility of the proposed torque control concept are demonstrated by experiments on a test stand. Finally, it is shown that using this torque control in an outer angular speed control loop also proves to be beneficial.     

欧姆龙工业网络控制系统集成

本文系统地论述了工业网络控制系统集成方式,并对各种构成形式和特点进行了讨论,给出了相应的系统集成结构。通过造纸厂板纸机控制系统集成实例,表明欧姆龙网络控制系统及其变频器在生产制造领域中的重要作用。     

基于工业控制网络的系统集成

本文系统地论述了工业控制网络的系统集成方式,并对各种构成形式和特点进行了讨论,给出了具体的系统集成结构。通过造纸厂板纸机控制系统集成实例,表明了系统集成在生产制造领域中的重要作用。     

Two-dimensional charge-control model for MODFET's

A dc model for MODFET's accounting for two-dimensional effects is proposed. In this model, charge control is realized by solving the two-dimensional Poisson equation in the depleted AlGaAs region. The transport picture used for the two-dimensional electron gas (2-DEG) in the AlGaAs/GaAs heterojunction relies on the quasi-Fermi level together with a field-dependent mobility and therefore includes 2-DEG diffusion effects. Our approach reduces the analysis to a single integral equation.I-Vcurves, which provide a good fitting to the reported experimental data, are obtained using a smooth velocity-field curve. The channel voltage, 2-DEG concentration, parallel electric-field, and drift velocity along the channel are given in this study and provide a clear picture of current saturation. The model is consistent with the approximate two-region saturation picture but provides a smoother transition. We observe a large diffusion current component along the channel in addition to the drift current. However, the total saturation current obtained has nearly the same value as found from the two-region model. This new model with two-dimensional charge control provides much insight into the current saturation mechanism of the MODFET.     

盾构机土仓压力自动控制技术

盾构机土仓压力的大小直接影响到掘进工作面的稳定性和地表的变形。根据盾构机土仓渣土的非线性本构关系,建立了土压平衡盾构机土仓压力控制数学模型。采用优化方法,提出了盾构机土仓压力优化控制算法。在实验台上,验证了盾构机土仓压力控制模型和算法的有效性。     

The effect of actuator saturation on the performance of PD-controlled servo systems

Perhaps the most often utilized means of closed-loop control of a servo system is proportional-derivative (PD) control. Linear analysis methods suggest the best tracking performance is achieved at maximum possible proportional and derivative gains. Maximum gains, however, drive the actuators into saturation, which renders the system nonlinear and the linear analysis invalid. This paper investigates the effect of actuator saturation on servo system tracking performance by formulating a frequency-based tracking performance measure roughly equivalent to the linear system −3 dB bandwidth. The proposed measure utilizes a series of band-limited pseudo-random tracking inputs to characterize the ‘bandwidth’ of the (nonlinear) saturating system. Numerical simulations based on this measure show that, for a servo system that exhibits actuator saturation, the best tracking performance is not achieved at maximum gain. Instead, performance improves up to a given gain, then begins to recede as the gain is increased further. The simulations also show that avoiding actuator saturation to ensure linear behavior significantly sacrifices tracking performance. The measure of tracking performance is compared with the −3 dB bandwidth utilized in linear analysis techniques, and the two are shown to be well correlated.     

A generalized machine learning-based model for the detection of DDoS attacks

As time is progressing, the number and the complexity of methods adopted for launching distributed denial of service (DDoS) attacks are changing. Therefore, we propose a methodology for the development of a generalized machine learning (ML)-based model for the detection of DDoS attacks. After exploring various attributes of the dataset chosen for this study, we propose an integrated feature selection (IFS) method which consists of three stages and integration of two different methods, that is, filter and embedded methods to select features which highly contribute to the detection of various types of DDoS attacks. We use light gradient boosting machine (LGBM) algorithm for training of the model for classification of benign and malicious flows. For ensuring satisfactory performance and generalized behavior of the developed model, we test it by passing records of unseen DDoS attack types. Several performance metrics are employed for the evaluation of the model. By comparing the performance of developed model against state-of-the-art models, we state an improvement of around 20% for almost all the reported metrics. We also show that the performance of the model improves if feature space is reduced by 77%. Furthermore, the generalized behavior of the developed model is justified by demonstrating a trade-off between high variance and high bias ML models.     

Modeling and sensorless control of an electromagnetic valve actuator

This paper presents the modeling and control of an electromagnetic valve actuator. The model is nonlinear and takes into account secondary nonlinearities like hysteresis, saturation, bounce and mutual inductance. Experimental methods for identifying parameters of the model are presented. Sliding mode control is utilized to reduce the seating velocity of the plunger as it strikes the core housing. This reduces actuator noise due to the high impact velocity of the plunger. In order to eliminate the need for position and velocity sensors, a nonlinear observer is developed that only employs coil current measurement. The position estimate is used as feedback to track a desired trajectory. The control objective is to minimize energy consumption and to reduce the seating velocity, which should improve actuator fatigue life and reduce impact noise. Simulation and experimental results are presented for an actuator designed and built in our laboratory. The experimental results show very good agreement with the analytical model.