内燃机用自由活塞永磁直流直线发电机分析

提出了一种新结构的自由活塞永磁直流直线发电机。电机为圆筒形,粘贴在动子支架上的永磁体由内向外沿径向充磁,通过内静子铁心与动子支架间的穿插配合,从静子上看动子只有一个磁极,静子上只有一组串联绕组,当永磁体动子朝一个方向运动时,电动势方向不变,可看作直流永磁直线发电机。通过三维有限元分析计算,指出设置磁路调整环的必要性;给出了有效削弱齿槽力波动的方法;得到了反映电机性能的电感、电动势和电磁推力等重要参数或曲线。     

Proposal and development of radial air‐gap coreless generator suitable for small wind turbine used in urban area

Independent distributed power generation using small wind turbines is becoming more widespread as wind power generation increases. Installation of small wind turbines in densely populated urban areas is not only useful from the viewpoint of extracting wind power sources in weak‐wind areas but also for making renewable energy easier to access when power supplies are closer to consumers. It is from this point of view that the authors proposed “urban wind power generation” using a collective system with a number of small vertical wind turbines, and have developed a suitable generator for low‐speed vertical wind turbines such as a Savonius windmill. Based on a standard coreless generator, the proposed generator is designed to make the direction of the magnetic flux radial in order to install the magnets and coils on the outer end of the generator. The change of magnet composition and flux direction maximizes the speed of the flux change and output voltage within a limited space. With the above configuration, the power of the proposed generator is independent of the diameter. In this report, the authors describe and evaluate the fundamental performance of a prototype of the proposed generator. Based on the experiments, a maximum output power of 283 W was obtained. The obtained starting torque is small enough to begin rotation under weak wind conditions of no more than 1 m/s. Therefore, it is clear that the proposed “radial” coreless generator is suitable for self‐starting and producing high power at low wind speed. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(1): 26– 34, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20695     

A salient‐pole synchronous generator with permanent magnets between the field poles

In this paper, a new salient‐pole synchronous generator (SG) termed the PMa‐SG is presented. In the PMa‐SG, permanent magnets (PMs) are placed between the pole shoes to reduce the magnetic saturation in the field poles. By using finite element analysis (FEA), the internal magnetic fields and basic characteristics of a 2.8‐MVA PMa‐SG are compared with those of a conventional SG of the same size, and the reduction effect of the magnetic saturation of the PMs is examined. The FEA simulations are also validated by experiments on a 2.0‐kVA prototype machine. The PMs placed between the pole shoes reduce the magnetic saturation in the pole bodies and pole tips and effectively increase the terminal voltage and output power. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(4): 58–67, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21132     

基于有限元方法的磁通反向电机定位转矩研究

本文介绍了一种新型双凸极永磁电机--磁通反向电机.该电机将永磁体和绕组均放置在定子上,具有转子结构简单、高功率密度、小电感、低惯性等优点,适于高速旋转的场合.但该电机的自身双凸极结构决定了其定位转矩较大,对转动平稳性和噪音控制等都有很大影响,因此文中通过有限元方法详细地分析了电机定转子齿宽、永磁体高度和斜槽角度这些参数的变化对定位转矩的影响,并在此基础上设计得到了一款样机.实验和仿真的比较结果相差约为8%,表明了有限元分析的准确性.     

并列式混合励磁磁通切换电机直流发电系统功率角线性控制策略

研究并实现了并列式混合励磁磁通切换电机直流发电系统。所提并列式混合励磁磁通切换电机拓扑在实现优良的磁场调节能力和故障灭磁能力的同时,避免了永磁体的短路和退磁。针对传统"调磁调压"控制策略动态能力差、电流谐波大以及直接转矩控制静态性能一般的不足,提出了功率角线性控制算法。该算法通过建立转矩与功率角的直接线性关系,在无电枢电流闭环环节的条件下,实现对功率角的直接线性调节,同时研究了能提高恒功率区域转矩输出能力的励磁电流调节方法。搭建了并列式混合励磁磁通切换电机直流发电系统实验平台,进行对比实验。实验结果表明,与直接转矩控制算法相比,采用功率角线性控制算法后电机转矩脉动、磁链纹波以及电流谐波含量均减小了,且采用该控制方法后,电机的动态性能良好。     

Mathematical simulations of the electromagnetic system of a subminiature magnetoelectric engine

This paper is devoted to simulations of a valve electric engine with excitation from high-energy permanent rare-earth magnets. A feature of the design of the engine under consideration is that a stator is manufactured using the polycapillary glass-fiber technique. The conductors of the distributed stator winding are placed in holes pm the tube wall. The cylindrical bipolar rotor is made of iron–neodymium–boron. The assumption accepted in the work during the solving the Laplace equation has made it possible to obtain analytical solutions for the magnetic flux, emf, current, electromagnetic torque, and electromagnetic power.     

大型汽轮发电机匝间短路保护必要性探讨

介绍了陡河发电厂４例发电机定子绕组短路故障情况,认为发电机定子绕组的同槽同相,发电机制造工艺的缺陷及绝缘材料的老化均可能造成匝间短路,因此有必要装设匝间保护。     

Mathematical simulation of a high-speed single-phase machine with alternating current direction

A new design of a single-phase flux reversal machine (FRM) and a procedure of mathematical simulation of the FRM are described in this article. Technical features of the FRM (such as efficiency, specific power, and specific torque) that are close to those of synchronous motors with magnets on the rotor have greater reliability for high speed applications. The main advantages of an FRM involve the absence of permanent magnets or electric conductors on a rotating rotor and their being positioned on a stator. The new design of a single-phase FRM consists of a rotor with four teeth and a stator with four teeth and a magnetic system. The magnetic system on the stator teeth surface has two magnets on each stator tooth and generates two magnetic poles on each one. The adjacent poles on the adjacent teeth of stator are similar. The total angular size of new design is slightly less than the perimeter of the circle. Therefore, the stator surface is much better used (unlike the prototype), which results in an increase in the specific power and power efficiency, as well as a decrease in the cost of the FRM. A method for mathematical simulation of an FRM that is based upon solving magnetostatic problems with common geometry is proposed. Different positions of the rotor are simulated by joining boundary conditions. The method allows one to determine the electric losses in steel and magnets in postprocessing.     

A lightweight linear actuator with concentratedly placed stationary coils

This paper presents a novel lightweight linear actuator using permanent magnets and having its coils on the stator concentratedly. The rated force is 6 N, the stroke is 30 mm, and the weight is below 300 g owing to its unique structure. The machine is to be applied to, e.g., a pick‐and‐place actuator of tiny electronic parts, and the performance for the application is confirmed through experiments with a prototype. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(4): 59–67, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20158     

High torque induction motor with rotating magnets in the rotor

This paper describes a new type high torque induction motor which has the rotating magnets in the rotor. The motor basically consists of a usual stator, cylindrical rotor, and inner cylinder of which the surface is covered by a set of magnets. The rotor turns at somewhat less than synchronous speed. The inner cylinder with magnets can revolve freely against a rotor shaft. The magnets revolve synchronized by the rotating magnetic field induced by the stator current. The magnets make the flux in the rotor. Then we can expect torque increase by the increase of the flux. The results of magnetic field analysis indicate the flux is increased. In the experimental results of a test motor which is a 400 W prototype machine, we have obtained the torque increase by approximately 20 percent as anticipated in the magnetic field analysis. Moreover, test results show improvements of efficiency and power factor in the motor operations. The efficiency of the test motor is obtained as high as 10 percent at the rated output over those of a same size conventional induction motor. Although power factor of conventional induction motors is lagging at all times, the test motor can be operated with near unity, leading or lagging by adjusting the ac supplied source voltage.     

A fault location method using air‐gap fluxes of synchronous generator

This paper deals with an experimental investigation of a novel fault location method using air‐gap flux distributions of a synchronous generator connected to a power system. Air‐gap fluxes are the sum of field fluxes and armature reaction fluxes. Changes in armature current and field current at a fault contribute directly to the armature reaction fluxes and field fluxes, then resultant air‐gap fluxes. Therefore, air‐gap fluxes can be utilized to locate a fault. Wavelet analysis is applied to the induced voltages of search coils, which are wound around a stator tooth top for measurement of the air‐gap flux. It is shown that the fault type and location can be estimated based on the change in the search coil voltages measured during the fault. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(3): 20–27, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20707     

TR08磁浮列车空气隙磁通密度的计算

提出一种基于解析计算方法的磁浮列车空气隙磁通密度的计算方法。首先对磁浮列车定子、动子电流层密度进行傅里叶级数展开,然后借助谐波分析方法,计算出磁浮列车悬浮气隙中的磁通密度。解析方法的结果与ANSYS模型分析的空气隙磁通密度相比较,证实了解析分析和模型分析的一致性和所采用的解析计算方法的正确性和有效性。此方法为进一步建立磁浮列车的实时运动控制模型提供了基础。     

Design and performance analysis of a 700‐kW wound‐rotor BDFIG for ship shaft generator application

In this paper, a 700‐kW brushless doubly fed induction generator (BDFIG) is designed for stand‐alone ship shaft generator application. Based on the principle of tooth harmonics and sinusoidal winding structure, a multi‐pitch unequal‐turn‐coil wound rotor is adopted to reduce harmonic contents and couple the two stator windings effectively. The performance analyses of a prototype BDFIG with two/four pole pairs are presented. The magnetic fields, air‐gap flux densities, and current densities with full load at different shaft speeds of the prototype machine are investigated. Simulation analysis and experimental tests verify that the output capability and the efficiency of the prototype machine could meet the design requirements of a 700‐kW generator and that the wound rotor structure is suitable for high‐power brushless doubly fed machines. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Performance and conceptual design of superconducting magnet for disk MHD generator

This paper describes superconducting magnets coupled with two kinds of disk-type MHD generators. One is coupled with a disk generator in the closed-cycle MHD experimental facility FUJI-1. The other is for a full-scale disk MHD generator. These are split-pair magnets. In the magnet for the FUJI-1 facility, a unique structure which supports the coils against the electromagnetic force has been fabricated and the magnet has been operating stably. During MHD power generation experiments, an induced voltage across the terminals of the coil was measured. A magnitude of the Faraday current in the generator was calculated from this induced voltage. A possible construction of magnetics for a full-scale disk MHD generator is indicated. It is suggested that a high performance of the generator (output power density of 0.3-1 GW/m³) can be obtained with high magnetic field up to 10 T.     

CHARACTERISTICS OF THE FORCE COMPONENTS OF AN AIR-CORED LINEAR SYNCHRONOUS MOTOR WITH SUPERCONDUCTING EXCITATION MAGNETS

ABSTRACT

A method of calculation is presented to analyze the various characteristics of an air-cored linear synchronous motor, which has been proposed as the propulsion system for high-speed magnetically levitated vehicles. The method uses firstly Biot-Savart's Law to determine the magnetic flux density vector and then Ampere's Law to calculate the forces and moments acting on the individual conductors of the stator winding as well as on the superconducting excitation magnets. Both the effects of stator winding geometry and of current harmonics in the power supply will be investigated.     

大型汽轮发电机定子线圈股间电压分布分析

以1000MW级大型汽轮发电机定子线圈为例,采用漏感电势法对股线的漏磁感应电势和股间电压分布情况进行了研究,为胶化线圈绝缘结构设计、制造过程工艺改进及股间短路试验方法的优化等提供一定的理论帮助。     

交流励磁发电机定子磁场定向的矢量控制研究

论述了交流励磁发电机基于定子磁场定向的控制原理,推导了发电机有功功率、无功功率与转子励磁电流的关系,搭建了交流励磁发电机双闭环控制模型,讨论了定子磁链幅值和位置的确定,进行了采用PID调节器双闭环控制的仿真研究,结果表明定子磁场定向的矢量控制原理能够实现对交流励磁发电机有功和无功功率的快速、解耦控制     

双边永磁励磁游标电机运行原理及电磁特性仿真研究

为了进一步提高电机的功率密度和转矩密度,以满足直驱系统低速、大转矩的运行工况,提出一种新型双边永磁励磁游标(DPMEV)电机。该电机定子和转子上均放置有永磁体,利用定、转子齿对气隙磁导的双向调制作用,将两组永磁体产生的永磁磁场调制成少极数、高转速的有效谐波磁场,并根据有效谐波磁场设计电枢绕组,从而使定、转子上两组永磁体同时与电枢绕组耦合。介绍了DPMEV电机的拓扑结构。基于等效磁路法,对该电机的气隙磁通密度进行了分析,表明该电机可利用气隙磁导的双向调制作用,实现电机功率密度和转矩密度的有效提高。在深入分析电机工作原理的基础上,通过有限元法对DPMEV电机进行了计算和分析,验证了该电机具有适用于直驱系统的高功率密度和高转矩密度特性。     

异步化发电机定子端部发热的研究

本文从异步化发电机的相量图出发,提出了确定合成端部磁通的方法。文章还分析了异步化发电机不同无功运行时定子端部合成磁通的大小,并比较了异步化发电机和同步发电机深度吸收无功时合成端部磁通大小的差异。最后讨论了根据合成端部磁通的大小估计定子铁心端部的温升。     

Design and analysis framework for linear permanent-magnet machines

This paper presents a design and analysis framework for the general class of permanent magnet electric machines. In the authors' analysis, surface-mounted linear motors consisting of permanent magnets and ironless current-carrying coils are treated in a uniform way via the magnetic vector potential. This analysis is developed to design novel linear magnetic levitators for driving precision motion control stages such as those used in wafer steppers. For one such motor structure, they give analytical formulae for its magnetic field, force, flux linkage, inductance of the winding, and back electromotive force. They provide experimental results with a six degree-of-freedom magnetic levitator. These results are in good agreement with analytical estimations. The levitator uses a permanent-magnet Halbach array in order to improve its power efficiency. By analogy, there also exists an electromagnetic dual of the Halbach array. One such dual utilizes a triangular winding pattern in order to achieve a primarily single-sided magnetic field