A Novel Fuzzy Direct Torque Control System for Three-level Inverter-fed Induction Machine

Diode clamped multi-level inverter （DCMLI） has a wide application prospect in high-voltage and adjustable speed drive systems due to its low stress on switching devices, low harmonic output, and simple structure. However, the problem of complexity of selecting vectors and capacitor voltage unbalance needs to be solved when the algorithm of direct torque control （DTC） is implemented on DCMLI. In this paper, a fuzzy DTC system of an induction machine fed by a three-level neutral-point-clamped （NPC） inverter is proposed. After introducing fuzzy logic, optimal selecting switching state is realized by applying various strategies which can distinguish the grade of the errors of stator flux linkage, torque, the neutral-point potential, and the position of stator flux linkage. Consequently, the neutral-point potential unbalance, the dr/dr of output voltage and the switching loss are restrained effectively, and desirable dynamic and steady-state performances of induction machines can be obtained for the DTC scheme. A design method of the fuzzy controller is introduced in detail, and the relevant simulation and experimental results have verified the feasibility of the proposed control algorithm.

Performance Description of Brushless Doubly-Fed Induction Machine in Its Asynchronous and Variable Speed Synchronous Modes

Brushless Doubly-Fed Machine has attracted considerable attention in recent years due to its advantages. It has the robustness of the squirrel cage induction machine, and the speed and power factor controllability of the synchronous machine as well as the absence of brushes and slip rings, and using a fractionally rated frequency converter. Hence, there are considerable benefits over the conventional machines, when the machine is applied to applications such as a wind turbine generator or high power adjustable speed drive. However, these benefits are obtained in slightly more complex structure, higher cost and larger dimensions in comparison to the conventional induction machine. This paper presents fundamental aspects of the three modes of operation of brushless doubly fed machine, i.e. simple induction mode, cascade induction mode, and synchronous mode. The investigation is performed by analyzing the spatial harmonic contents of the rotor magnetic flux density. The direct cross couplings between stator and rotor fields as well as, indirect cross coupling between stator fields by the special rotor of this machine is described. Furthermore, loss analysis of the machine in various modes is presented and the torque-speed curves for asynchronous modes are obtained. A 2-D magnetodynamic finite element model based on the D-180 4/8 pole prototype machine is extracted and simulated to verify the results.

Parameter Deviation Effect Study of the Power Generation Unit on a Doubly-Fed Induction Machine-based Shipboard Propulsion System

To lower the difficulty of fault protection,a doubly-fed induction machine based shipboard propulsion system(DFIM-SPS)that is partially power decoupled is presented.In such an intrinsically safe SPS architecture,a synchronous generator(SG)is employed for power generation,and the accuracy of the parameters of power generation unit(PGU)plays an important role in SPS stable operation.In this paper,the PGU parameter deviations are studied to evaluate the effects on system performance.The models of salient-pole SG,type DC1A excitation system(EXS)and DFIM are illustrated first.Besides,the corresponding control scheme is explained.For the 16 important parameters of PGU,up to 40%of parameter deviations are applied to implement parameter sensitivity analysis.Then,simulation studies are carried out to evaluate the parameter deviation effects on system performance in detail.By defining three parameter deviation effect indicators(PDEIs),the effects on the PGU output variables,which are the terminal voltage and output active power,are studied.Moreover,the increasing rates of PDEIs with different degrees of parameter deviations for the key parameters are analyzed.Furthermore,the overall system performance is investigated for the two most influential PGU parameters.This paper provides some vital clues on SG and EXS parameter identification for DFIM-SPS.

Thrust Characteristics Analysis of Long Primary Double Sided Linear Induction Machine with Plate and Novel Shuttle Secondary Structure

The air-gap flux density formula and thrust expression of long primary double sided linear induction machine(DLIM)in the secondary motion reference frame are deduced by using the Maxwell equations firstly.Then,by analyzing the factors that affect the thrust ripple in the thrust expression,a shuttle type secondary structure of long primary DLIMs is proposed,and its thrust performances of the machine with different shuttle size combinations are simulated and compared with that of plate secondary long primary DLIM.Comparison results show that the new secondary structure can suppress the thrust ripple and improve the stability of system acceleration.

NOVEL SENSORLESS VECTOR CONTROL SYSTEM OF INDUCTION MACHINE BASED ON FLUX OBSERVER IN FIELD WEAKENING

为正式就职机器(IM ) 的一个 speed-sensorless 向量控制系统被介绍。根据 IM 的向量控制理论，转子流动基于一个流动观察员被估计，并且速度通过 c7~axis 转子流动与比例的不可分的管理者在零上收敛的方法被估计。0。75 kW， 50 Hz，二杆的正式就职机器在模拟和试验性的确认被使用。模拟模型在 Matlab 被构造。测试的 Aseries 在削弱区域的地里被执行，为以资产净值出售、装载的操作。估计的速度在基于的速度区域追踪实际速度很好“并且域变弱区域(1 每每联合起来统一值到 4 珍视) 。剩余速度的小评价错误由于存在滑倒。

NEW PUNCHING MACHINE DRIVEN BY LINEAR INDUCTION MOTOR

The research and application of the punching machine driven by a linear induction motor(LIM)are introduced.The fundamental principle, construction, performance and application are described. Comparing this new model machine with its traditional form, the LIM driven punching machine has many great advantages, such as, simple construction, small size and mass, low production cost, short production time, easy to control, low noise and considerable energy saving.

Machine Learning Controller for DFIG Based Wind Conversion System

Renewable energy production plays a major role in satisfying electricity demand.Wind power conversion is one of the most popular renewable energy sources compared to other sources.Wind energy conversion has two major types of generators such as the Permanent Magnet Synchronous Generator(PMSG)and the Doubly Fed Induction Generator(DFIG).The maximum power tracking algo-rithm is a crucial controller,a wind energy conversion system for generating maximum power in different wind speed conditions.In this article,the DFIG wind energy conversion system was developed in Matrix Laboratory(MATLAB)and designed a machine learning(ML)algorithm for the rotor and grid side converter.The ML algorithm has been developed and trained in a MATLAB environment.There are two types of learning algorithms such as supervised and unsupervised learning.In this research supervised learning is used to power the neural networks and analysis is made for various hidden layers and activation functions.Simulation results are assessed to demonstrate the efficiency of the proposed system.

Electromotive Force Calculation of Fifteen-phase Induction Motors With Non-sinusoidal Supply

非正弦供电十五相感应电机基波磁动势正幅值与3次谐波磁动势负幅值不在同一位置时的叠加磁动势波形称为常规磁动势波形,此种情况下感应电动势的计算是该种电机电磁性能分析与优化设计的前提。与正弦磁动势或理想叠加磁动势不同,常规磁动势下电机的感应电动势与激磁电流相位因磁路饱和不再相差/2,为此提出把感应电动势作为激磁电流流控电压源的处理方法。鉴于电机每半个极下气隙磁密波形不再相同的情况,提出基于电机1个极距区域的拓展分布磁路法计算气隙磁密,进而求出基波感应电动势与3次谐波感应电动势。非正弦供电十五相感应电机样机的感应电动势计算值与实测值相互吻合,说明了拓展分布磁路法计算感应电动势有效且具有较高的准确度。

Quantitative Comparison of Electromagnetic Performance of Electrical Machines for HEVs/EVs

In this paper,various types of sinusoidal-fed electrical machines,i.e.induction machines(IMs),permanent magnet(PM)machines,synchronous reluctance machines,variable flux machines,wound field machines,are comprehensively reviewed in terms of basic features,merits and demerits,and compared for HEV/EV traction applications.Their latest developments are highlighted while their electromagnetic performance are quantitatively compared based on the same specification as the Prius 2010 interior PM(IPM)machine,including the torque/power-speed characteristics,power factor,efficiency map,and drive cycle based overall efficiency.It is found that PM-assisted synchronous reluctance machines are the most promising alternatives to IPM machines with lower cost and potentially higher overall efficiency.Although IMs are cheaper and have better overload capability,they exhibit lower efficiency and power factor.Other electrical machines,such as synchronous reluctance machines,wound field machines,as well as many other newly developed machines,are currently less attractive due to lower torque density and efficiency.

Recent Development of Linear Machine Topologies and Applications

Linear machines(LMs)produce linear motion without any intermediate transmission mechanisms,thus the whole electromechanical system has simple structure and its efficiency is high.Because of such merits,linear machines have been studied for a long time and rapidly developed in recent years.Due to the characteristic of open structure,linear machines have more diversity than rotary machines in terms of machine topologies.Accounting for the wide applications of linear machines,e.g.Maglev train,precision machine tools,semiconductor processing device,automatic equipment,logistic transport line,ropeless lifter,compressor,etc.,this paper reviews the most applied linear machines including machine topologies,operating principle and features.In addition,the influence of end effects and the corresponding reduction methods are also summarized.Finally,several commercial applications are exemplified.

Square-Wave Drive for Synchronous Reluctance Machine and its Torque Ripple Analysis

Synchronous reluctance machine(SynRM)can be perceived as a special type of permanent magnet synchronous machine(PMSM),and shares similar control method,i.e.the sine-wave current drive with sinusoidal phase currents.In this paper,square-wave drive,which is employed for permanent magnet brushless(BLDC)motors,is employed for the SynRM,in order to economically reduce the cost of rotor position sensor.It is revealed that the torque density and efficiency are slightly sacrificed,whereas torque ripple is deteriorated,proving the SynRM with square-wave drive still promising for the cost-sensitive application if torque ripple is not considered as a critical issue.To further investigate the additional pulsating torque under square-wave drive,mathematical model based on a-b-c phase inductance and d-q axis inductance are established,together with the time-stepping FE calculated currents.It is concluded that the harmonics in the currents tend to cause non-sinusoidal variation of the magnetic reluctance,which can be represented as additional inductance harmonics.The harmonics of the current and inductance interact with each other,thus undesirable torque ripple components are produced.

Improvement Torque Performances of Interior Permanent-Magnet Machines

Due to their excellent efficiency,power density and constant power speed region,interior permanent-magnet(IPM)machines are very suitable for electric vehicles(EVs).This paper proposed a new IPM rotor topology,which can offer high reluctance torque,wide constant power speed range and excellent overload capability.Besides,five rotor topologies with integral-slot distributed-windings IPM machines,including four existing IPM topologies and the proposed IPM topology,are designed optimally.Their characteristics,which include d-q axis inductances,saliency ratios,electromagnetic torques,corresponding torque ripples,back-electromotive forces(EMFs),overload capabilities and flux weakening performances are evaluated quantitatively.Finally,a three phase 48s8p hybrid rotor PM machine is built to verify the performances of the proposed IPM machine.This work provides some general concepts for machine developers who are willing to build IPM machines for high-performance EV applications.

HGR 2.0: A New Rule Induction Algorithm

This paper presents a new inductive learning algorithm, HGR (Version 2.0), based on the newly-developed extension matrix theory. The basic idea is to partition the positive examples of a specific class in a given example set into consistent groups, and each group corresponds to a consistent rule which covers all the examples in this group and none of the negative examples. Then a performance comparison of the HGR algorithm with other inductive algorithms, such as C4.5, OC1, HCV and SVM, is given in the paper. The authors not only selected 15 databases from the famous UCI machine learning repository, but also considered a real world problem. Experimental results show that their method achieves higher accuracy and fewer rules as compared with other algorithms.

ASSESSING THE DYNAMIC ERRORS OF COORDINATE MEASURING MACHINES

The main factors affecting the dynamic errors of coordinate measuring machines are analyzed. It is pointed out that there are two main contributors to the dynamic errors: One is the rotation of the elements around the joints connected with air bearings and the other is the bending of the elements caused by the dynamic inertial forces. A method for obtaining the displacement errors at the probe position from dynamic rotational errors is presented. The dynamic rotational errors are measured with inductive position sensors and a laser interferometer. The theoretical and experimental results both show that during the process of fast probing, due to the dynamic inertial forces, there are not only large rotation of the elements around the joints connected with air bearings but also large bending of the weak elements themselves.

高精度视觉感应技术在水肥一体机中的应用

以农田水肥智能化管理为研究对象,构建了一种高精度视觉感应式水肥一体机。采用高精度视觉感应技术获取作物生长状态参数图像,基于超像素图像分割技术,对复杂的作物生长状态图像特征向量进行提取,采用模糊聚类算法对图像进行分割处理,根据目标图像的像素值统计结果进行生长状态预测,并结合环境参数信息,构建灌溉过程土壤电导率EC和pH预测模型。测试结果表明:水肥一体机控制系统能够有效预测作物对水肥需求,提高了灌溉过程混肥精度,可节约灌溉用水量、提升生产效率、降低人工成本。