新型双定子混合励磁风力发电机三维有限元分析及实验研究

提出一种新型双定子混合励磁风力发电机,分析电机的结构特点及工作原理,计算电机的空载磁场分布、静态特性及空载特性,并对样机进行实验研究。基于三维有限元方法,采用ANSYS软件计算了电机的空载磁场分布,得到了空载内外定子电枢绕组磁链、内外定子电动势及合成电动势;根据磁链法分别计算了电枢绕组和励磁绕组电感等参数;分析了电机额定转速400 r/min时的空载特性。理论分析与实验结果表明：采用双定子的电机结构可使电机空载相电动势比相同条件下的单定子电机增加约23%;通过调节励磁电流,发电机相电动势在90~110 V之间变化。由圆套筒型整体永磁体组成的串联磁路并设置2个定子的新型电机结构可有效地提高低速电机的发电能力;双定子混合励磁风力发电机具有较好的调磁性能。     

双绕组高压发电机外部故障仿真模型

建立了双绕组高压发电机的详细电路分析数学模型。模型可以用来分析双绕组高压发电机的稳态运行、外部相间故障或接地故障。采用理论分析方法计算了高压发电机的两套三相定子绕组的自感和互感,并且以11 MW、45 kV的双绕组高压发电机为模型,给出了稳态运行和故障时的仿真结果。利用该模型可以对高压发电机的保护方案进行有效的验证或者作相应的改进。     

Analysis of armature reaction and winding inductances of permanent magnet brushless DC motor with deep slot concentrated coils

Based on the configuration of deep slot concentrated coils, an analytical model is developed for predicting the armature reaction field produced by the 3-phase stator windings of permanent magnet brushless DC motors with concentrated coils by using the image method and the analytical functions of the armature reaction and winding inductances are proposed accounting for the influence of stator slotting. This approach is different from the method of equivalent distributed current sheet and more suitable for electric machines, which have concentrated coils and deeper slots. Under different control mode, the different analytical functions are presented. This will be helpful when further analyzing the performance of the motor. The results agree with the experiment very well. __________ Translated from Proceedings of the Chinese Society for Electrical Engineering, 2005, 25(12): 127–132 (in Chinese)     

Design and modeling of a slotless and homopolar axial-field synchronous machine for a flywheel accumulator

A new axial-field synchronous machine designed for a flywheel accumulator is presented herein. The armature and field windings, fixed in the air gap, are made with double-face printed circuits. A specific armature layout provides a sine-distributed magnetomotive force and solves the problem of crossing the ends of the winding. A two-dimensional semi-analytical model at the mean radius, using surfacic permeances, is then developed. Then, inductances, torque, and eddy-current losses are calculated using this model and compared with experimental results.     

Analysis of inductance characteristics for a bearingless permanent magnet synchronous motor

In this paper, the inductance characteristics of a 2-pole surface-mounted bearingless permanent magnet synchronous motor (BPMSM) with 4-pole suspension force windings are investigated based on theoretical analysis and experimental investigation. Firstly, the winding configuration and operation principle of the BPMSM are presented. Secondly, the static and incremental inductances are defined. Then, based on the finite element (FE) analysis method, the static inductances of torque windings and suspension force windings in stator static coordinate reference are researched. In addition, the d- and q-axes static inductances in rotor revolving coordinate reference are obtained by 3/2 Transformation. Furthermore, taking the torque windings as an example, the incremental inductance of torque windings is studied, and the validity of the theory is confirmed by comparing the static and incremental inductances. Finally, the experimental study is carried out to verify the discussed numerical analysis. The results are helpful to measure parameters and build the mathematic model of BPMSMs, and lay a foundation for the further research on BPMSMs.     

集中绕组永磁无刷直流电机电枢反应及绕组电感的解析计算

基于深槽集中绕组的结构特点，采用镜像法，建立了适合集中绕组无刷电机的电枢反应求解模型。充分考虑电机齿槽影响，给出了电枢反应磁场的解析表达式，对不同控制方式下的电枢反应分别作了研究，并在此基础上推导了电机绕组电感的通用求解公式，从而为集中绕组无刷电机的参数设计和特性分析提供了理论依据。样机实验表明，其具有很好的工程适用性，理论计算与实测值吻合。     

MAGNETIC FIELDS AND INDUCTANCES OF HELICAL WINDINGS WITH 120° PHASEBANDS

ABSTRACT

In the development of superconducting a.c. generators the essential air-cored nature of the generator, and the large power output per unit length, suggests that conventional armature windings may not necessarily be the most suitable. One possible alternative is the helical armature winding (3) - (8) and has been proposed both as a means of obtaining a uniformly supported armature structure and for generating at transmission line voltages.

This paper discusses the peculiarities of helical windings, and in particular those with 60 and 120° phase-bands. Magnetic field and inductance measurements are made on a three phase model with a phase spread of 120° and compared with calculated values using a previously published theory (4). Computed and measured values of synchronous inductance agree to within 1%.     

A Novel Dual-Stator Hybrid Excited Synchronous Wind Generator

This paper presents a novel dual-stator hybrid excited synchronous wind generator and describes its structural features and operation principle. The no-load magnetic fields with different field currents are computed by 3-D finite-element method. Static characteristics, including the flux-linkage and EMF waveforms of stator windings, and inductance waveforms of armature windings and field winding, are analyzed. The simulation results show that due to the dual-stator structure, the air-gap magnetic flux can be easily controlled, while the output voltage can be increased effectively. Tests are performed on the prototype machine to validate the predicted results, and an excellent agreement is obtained.      

Determination of Synchronous Reactance and No‐Load Saturation Curve of Synchronous Machines by dc Test Considering Magnetic Saturation Effect

dc Tests can accurately determine the unsaturated synchronous machine‐equivalent circuit constants by a simple standstill test. This paper presents two improved dc tests that account for the magnetic saturation of the stator iron core by the main flux. These tests are tentatively named Step Response Test (I) and Step Response Test (II). The former can predict the incremental d‐axis synchronous reactance by performing a Fourier transform of the voltage and current measured when a small step voltage is applied to the two armature terminals as a field current flows. The latter can determine the incremental d‐ and q‐axes synchronous reactances by the same Fourier transform of the voltage and current measured when a small step voltage is applied to the two armature terminals as an armature current flows. In addition, this paper introduces a new method to calculate not only the static d‐ and q‐axes synchronous reactances but also the no‐load saturation and short‐circuit characteristic curves. This new method does not require the results from any additional tests including the rotational driving tests and dimensional information, which can only be obtained from the manufacturer. To demonstrate the validity of the proposed method, results of an experiment using 10‐kVA laminated synchronous machines with damper winding are presented.     

交直流混合供电发电机定子绕组端部漏电感的计算

在考虑绕组端部的喇叭口和绕组上下层位置的条件下 ,推导了交直流混合供电发电机绕组端部漏电感的计算公式 ,根据公式编制了端部漏电感的计算程序 ,计算结果与样机上测试线圈的实验结果进行了比较。     

隐极同步发电机励磁绕组匝间短路的多回路电感参数计算

为了对故障中各种电气量进行准确仿真分析以揭示隐极同步发电机励磁绕组匝间短路的故障机理,需要准确计算电机的各种参数,尤其是与发生匝间短路的励磁绕组有关的电感参数.从隐极同步电机分布式励磁绕组在各极下的单个同心式线圈出发,应用气隙磁导的概念和谐波分析的方法计算与单个励磁线圈有关的电感参数,并按照故障的励磁绕组的实际连接情况进行叠加,得到了与励磁绕组各回路有关的多回路参数模型.该模型考虑了励磁绕组故障回路产生的各种谐波磁场的作用,并通过具体算例间接说明了其合理性.将该参数模型用于励磁绕组匝间短路故障的多回路计算,计算结果与样机实验吻合,验证了参数模型的准确性.     

内置式永磁同步电机电感参数的研究

分析了永磁体磁势和电枢磁势共同作用时内置式永磁同步电机的电感特性,基于交流静态法,提出了一种改进的测量内置式永磁同步电机定子自感和互感以及交直轴电感的方法。为了考虑饱和和交叉耦合效应对电感参数的影响,该方法首先根据所测电压和电流数据计算出不同转子位置和电流下的磁链,然后根据磁链计算出电机自感和互感以及交直轴电感参数,并应用该方法进行了实测研究。结果表明,实测结果与有限元分析结果吻合较好,验证了该方法的可行性和有效性。     

Characteristics of a brushless and exciterless three-phase synchronous generator with DC exciting system

From the viewpoint of maintenances and constructions, it is desirable that brushless and exciterless type three-phase synchronous generators be made. To meet this requirement, one of the authors devised a brushless and exciterless synchronous generator in which exciting currents flow simultaneously with load currents in armature windings. Thus, generators can be used both as the generators themselves and as the exciters. A generator system has already been reported by one of the authors. In it, the dc stator exciting current flows between the middle points per phase of the double-star armature winding through the rectifiers. However, the winding connection between the armature winding and the rectifiers are complicated. Three sets of rectifiers are needed by the stator excitation. The authors present a generator system by which the electric connection of between the stator armature winding and the rectifier can be simplified, and the number of the rectifiers can be reduced. In this system, the stator is provided with a double-star armature winding having two neutral points. In this paper, first, a circuit constitution and the principle for the brushless and exciterless three-phase synchronous generator are described, and second, the characteristics are elucidated by means of characteristic analysis. Further, the results of the experiments for the generator conducted on the test machine of 2.0 kW are shown.     

A method to determine direct‐ and quadrature‐axis inductances of permanent magnet synchronous motors

The equivalent circuit constants of permanent magnet synchronous motors are needed in the calculation of operation characteristics, construction of a control system, etc. These constants can be computed from the data on structural form and materials. However, measurements are necessary to obtain highly precise values. Methods for measurement of the d‐ and q‐axis inductances can be roughly divided into rotational and standstill methods. The standstill methods have the advantage that they are easy to carry out. However, it is difficult to consider magnetic saturation and distortion of the change in the armature winding inductance. The accuracy of the standstill method can be improved if these effects can be readily taken into account. This paper describes a standstill method for measuring accurate d‐ and q‐axis synchronous inductances of permanent magnet synchronous motors. By utilizing the fact that the EMF interference terms in the motor voltage equation considering the distortion of the inductance change are equal to zero when the rotor is in a specific position, the proposed method determines the inductances considering both magnetic saturation and inductance distortion effects from simple off‐line standstill testing. In addition, this method is capable of taking cross‐magnetic saturation into account when used with the necessary testing equipment. The proposed method was implemented on a 0.4‐kW interior permanent magnet synchronous motor with concentrated stator winding. The validity of the proposed method was demonstrated by comparing the measured and calculated results of the no‐load and on‐load characteristics. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(3): 41–50, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20969     

基于双谐波绕组的混合励磁发电机励磁控制系统

为了解决不同运行工况下混合励磁同步发电机端电压恒定的问题,设计了一种基于全桥变换器拓扑的励磁控制系统。励磁系统采用以电枢绕组电压为外环、定子谐波励磁绕组电流为内环的双闭环控制策略,以谐波无刷混合励磁同步发电机端电压为反馈信号,通过调节定子谐波励磁绕组电流,以维持发电机端电压恒定。阐述了双谐波绕组的混合励磁发电机的基本结构和工作原理,设计了励磁控制系统的软硬件,并测试了励磁控制系统的性能。实验结果表明：调节定子谐波励磁绕组电流,可以很好的调节发电机的端电压;通过励磁控制系统的自动调节功能,实现了发电机在不同负载情况下的输出电压恒定。     

同步发电机励磁绕组匝间短路故障稳态数学模型及仿真

励磁绕组匝间短路故障会造成发电机励磁电流增大、输出无功功率减小、振动加剧等.为实现故障在线监测与保护,需准确快速计算故障电流等电气量.应用交流电机的多回路理论,基于对故障时定、转子电流稳态特征的分析,得到各回路电流的稳态表达式;根据同频率量相等的原则,将稳态时的微分方程组转化为线性代数方程组,得到励磁绕组匝间短路故障的稳态数学模型;利用高斯消去法可直接求得所有回路电流中各种交、直流分量的稳态解,快速实现故障的稳态计算.对一台12 KW、3对极的隐极同步发电机进行了空载时励磁绕组匝间短路实验,稳态仿真结果与实验吻合较好.该方法可比暂态仿真减少90%的计算时间,为同步发电机励磁绕组匝间短路故障的监测与保护奠定了基础.     

Basic Design Method for SPMSM Based on Air‐Gap Magnetic Flux Density Distribution Focusing on Image Magnetic Pole

This paper presents a basic design method for the surface‐mounted permanent magnet synchronous motor (SPMSM) for both distributed and concentrated windings. The design is based on the air‐gap magnetic flux density distribution focusing on the image magnetic pole. The calculus equation of the air‐gap magnetic flux density distribution is analytically derived by supposing the magnetic pole is located on the magnet surface and image planes. In this study, a three‐phase and double‐layer stator winding SPMSM that has a linear demagnetizing characteristic magnet, such as a ferrite or rare‐earth magnet is considered. From the required specifications and design conditions, the design target values of the parameters that appear in the voltages equations of the d–q axis coordinate system are calculated. Then, the relational equations for the torque constant, d‐axis inductance, copper loss, and the maximum current density are presented as a function of three design parameters under i_d = 0 control. They are the stator stack length, the number of coil turns in series in a phase, and the slot bottom length. Hence, this approach reduces the SPMSM basic design to the problem with these design parameters has to be solved. The proposed method makes it possible to address the concentrated winding as a special case of the distributed winding. The FEA results confirm the validity of the proposed basic design method for both distributed and concentrated windings.     

多相圈式绕组电机的定子端部漏感计算

建立了圈式绕组感应电机定子端部的空间模型。以Biot-Savart定律为基础,通过剖分线圈的端部面积,推导了定子绕组为圈式时的多相电机的端部互漏感计算公式。利用Matlab编写了相应的计算程序,计算出了某型样机的定子线圈端部互电感。结合回路电流分析法,计算了样机在不同短距系数下的定子相漏感,并对计算结果进行了分析与验证。     

新型混合励磁永磁同步电机齿谐波电动势的协调控制

对于利用齿谐波磁场来励磁的混合励磁永磁同步电机,希望转子齿谐波绕组中感应的用来励磁的齿谐波电动势足够大,而定子电枢绕组中感应的影响电动势波形的齿谐波电动势尽可能小。为了实现这一目标,分析了齿谐波电动势产生的机理,找到了影响定、转子绕组齿谐波电动势大小的主要因素,并进行了详细的讨论,得出了一些实用的结论。最后,对一台齿谐波励磁的混合励磁永磁同步发电机进行了理论计算和实验,计算结果和实验结果的比较验证了理论分析的正确性。     

A Flux‐Modulating Synchronous Machine with Permanent Magnet Excitation

This paper presents a novel type of flux‐modulating synchronous machine (FMSM) in which permanent magnets (PMs) are embedded in the stator back‐iron. The rotor has neither windings nor PMs. A prototype machine with an outer‐rotor configuration was designed and manufactured to validate the operating principle of the FMSM. The characteristics in the motor mode of the prototype machine were also investigated with a vector control system. The results of the investigations show that, as in surface‐mounted PM motors, the torque of the FMSM is predominantly generated by the PM flux and can be controlled using the armature current.