机网暂态过程数值仿真中的同步电机模型

提出了一种新的适用于电力系统机网暂态过程数值仿真的无阻尼组同步电机模型,通过采且“先求通解,再用梯形法求积”的方法对同步电机的电压方程组进行差分化,成功地消除了因旋转电势引起的、存在于同步电机直轴电压方程和交轴电压方程之间的耦合,导出了相互解耦的直轴和交轴瞬态等值电路。通过算例比较了该模型与ＥＭＴＰ模型的仿真结果,证明这种新模型是正确的,其仿真算法比ＥＭＴＰ算法更精确、更稳定。     

Design of Linear Induction Drives by Field Analysis and Finite-Element Techniques

Two-dimensional field and finite-element analyses are complementary in evaluating the performance of single-sided linear induction machines, and can be used to develop a machine design for a given drive application. Electromagnetic analysis leads to an equivalent circuit of the machine with speed-and frequency-dependent parameters, in which top cap geometry, core hysteresis and saturation, skin effect, eddy current reaction, and both transverse-edge and longitudinal-end effects can be included. Finite-element analysis provides detailed information on the magnetic field distribution to aid in machine design.     

A method for dynamic simulation of air-gap eccentricity ininduction machines

In this paper, a method is proposed which enables the simulation of the air-gap eccentricity in induction machines. The method is based on the coupled magnetic circuit approach. The model is derived by means of winding functions, and no symmetry in windings layout is assumed. The parameters of the model are calculated directly from the geometry and winding layout of the machine. The effect of eccentricity is included in calculation of machine inductances. It is shown that by proper modeling of the induction motor it is possible to determine the effect of eccentricity on the machine startup, whether the machine is running off a sinusoidal supply or a converter. Theoretical foundations of the technique, as well as the detailed differential equations describing the machine performance under rotor eccentricity are presented     

采用旋转因子法的同步电机模型

提出了一种新的适用于电力系统机网暂态过程数值仿真的有阻尼绕组同步电机模型。通过采用“旋转因子法”对同步电机的电压方程组进行差分化，成功地消除了因旋转电势引起的，存在于同步电机直轴电压方程和交轴电压方程之间的耦合，导出了相互解耦的直轴和交轴瞬态等值电路。文末的算例通过比较该模型与EMTP模型的仿真结果，证明这种新模型是正确的，其仿真算法比常用的EMTP算法更精确、更稳定。     

混合励磁爪极同步电机磁路结构及其调磁性能

在分析轴向/径向磁路混合励磁同步电机磁路与性能优缺点的基础上,提出了四种新结构轴向/径向磁路混合励磁爪极同步电机。详细分析了这四种电机的拓扑结构及磁路,给出相应的磁路图。采用三维有限元技术计算了不同励磁电流时电机气隙磁通。分析与计算结果表明,所提出的四种结构的混合励磁爪极同步电机,均具有较好的调磁性能,其中非对称交错永磁电机的弱磁和增磁性能最好,可满足宽调速同步电动机的需要。     

无刷双馈磁阻电机的等效电路与稳态特性分析

无刷双馈电机的定子具有极数和供电频率皆不相同的功率绕组和控制绕组,难以采用传统感应电机的等效电路进行稳态特性分析。根据两套定子绕组的电磁耦合关系特点,提出一种基于频率归算而无需进行极数归算的无刷双馈磁阻电机的等效电路。该等效电路与传统感应电机等效电路具有相似的形式,可用于无刷双馈电机稳态特性分析。文中介绍了采用该等效电路对一台5kW轴向叠片磁阻转子无刷双馈电机的稳态特性分析。仿真结果与实验结果相吻合,从而证明了所提出的磁阻转子无刷双馈等效电路的正确性和实用性。     

Finite-element models for cage induction motor analysis

Two methods for predicting the performance of cage induction motors using finite elements are described. The first, which is suitable for steady-state analysis, uses a phase-band model for the stator together with a single slot model for the rotor. These are used in an iterative procedure to determine the components of the familiar per-phase equivalent circuit. The second method, which is suitable for transient analysis, uses a time-stepped coupled circuit model for the machine, together with magnetostatic finite-element field solutions that are used to update the circuit parameters. Both methods are illustrated by comparison between experimental and computer characteristics for a four-pole 4.5 kW motor     

带交轴短路绕组的同步电机参数局部辨识

为改善带整流负载的同步电机的运行稳定性,在电机转子中设置了交轴短路绕组.建立了带交轴短路绕组同步电机的参数辨识模型,研究了利用最小二乘法实现参数的辨识,分析了待辨识参数的灵敏度.根据参数灵敏度大小,局部辨识了某电机的参数.结果表明,该方法是有效的.     

考虑谐波影响后交流励磁电动机电磁转矩的分析与计算

虽然已有不少文章研究了交流励磁电机的运行性能 ,但是很少有文章在研究其性能时考虑了谐波电流的影响 ,特别是谐波对电机电磁转矩的影响。本文从该类电机的基本电磁关系出发 ,分析研究了基波电磁转矩及谐波转矩的特点 ,提出了基波谐波的等效电路 ,给出了谐波电路中参数的计算方法。导出了基波电磁转矩、稳定谐波电磁转矩及脉动谐波电磁转矩的计算公式。文章最后以一个实际的绕线型异步电机用交 直 交电压型逆变器供给励磁的交流励磁电动机为例 ,计算了主要谐波的稳定和脉动的电磁转矩以及电机总的电磁转矩。计算结果对进一步研究系统的驱动性能及电机与励磁系统的设计是十分有益的。     

新型混合励磁同步电机的数学模型与等效分析

为改善高速永磁电机磁场调节困难的问题,提出一种新型混合励磁电机,转子上既有永磁极又有铁心极,磁路呈现典型的径向、周向和轴向三维特性,难以直接用解析法求取电感参数。根据新型混合励磁电机的磁路特点,提出一种等效分析方法,将复杂磁路的混合励磁电机等效为三种二维磁路电机轴向并列叠加。为了提高新型混合励磁电机电磁设计与性能分析的效率,推导了其数学模型与电感参数表达式。对一台10 k W混合励磁原理样机进行了有限元分析与实验研究,结果验证了所提数学模型与等效分析方法的正确性,为该类电机的设计和优化提供了理论支撑。     

抑制分数槽永磁电机轴电压定子斜槽法

特定极槽配合的分数槽永磁电机在空载情况下会产生固有轴电压,对轴承有着不可忽视的危害,同时对电机运行的稳定性及安全性也会造成极大的影响。斜槽作为电机性能优化的常用方法,对谐波的削弱也有着很好的效果,故可以采用定子斜槽法来削弱永磁电机空载轴电压的主要谐波。首先,基于磁路原理和法拉第电磁感应定律,推导出考虑斜槽时的分数槽永磁电机空载轴电压的解析模型,分析轴电压的主要谐波成分与斜槽数的关系,给出可使轴电压得到削弱的最佳斜槽数,然后利用二维有限元法分析了不同斜槽度下的4台分数槽永磁电机的空载轴电压,结果证明了解析分析的正确性和有效性。     

PERFORMANCE CALCULATIONS FOR INDUCTION MACHINES WITH A SOLID STEEL ROTOR

ABSTRACT

A method of calculating the performance characteristics for induction machines having solid steel rotors is presented. An equivalent circuit is derived in which the expressions for the circuit elements include the effects of rotor steel saturation, the finite length of the rotor, and the effect of induced rotor currents on the air gap flux density distribution. The analysis may be applied, with equal facility, to machines operating under conditions of constant voltage supply, or constant current supply. The accuracy of the method is demonstrated by comparison of torque/slip, power factor/slip, and current/slip curves that have been obtained by calculation and from practical tests. Results for three solid rotor machines of different rating, and pole number, are presented.     

双凸极变速永磁电机的变结构等效磁路模型

建立了双凸极变速永磁电机的变结构等效磁路模型,推导了气隙比磁导计算公式,通过求解所建立的非线性等效磁路方程,以计算电机的静态特性,计算中计及铁磁材料的非线性以及永磁磁场与电枢反应磁场之间经影响。通过引入适当的修正系数,使计算结果与有限元结果吻合。以新提出的12／8极双凸极永磁电机为算例,对电机的永磁磁链,空载电势,电感等静态特性进行了全面的分析计算,并考虑了转子斜槽对静态特性的影响,所得结果与实测值一致,表明该文所提出了作方法可以快速、有效地分析计算双凸极永电的磁场及静态特性,适合于需要考虑不同结构参数对电机特性影响的应用场合,如优化设计等。     

Two-Dimensional Field Analysis of Cylindrical Machines with Permanent Magnet Excitation

The design of the magnetic circuit of permanent magnet machines differs from that of conventional wound field machines mainly due to the low magnetic permeability of the magnets. A two-dimensional field analysis is presented which takes the magnet leakage, the distribution of magnet MMF along its height, and the changing magnet width into consideration. The fundamental component of flux calculated by the model is compared with results obtained by finite element analysis for different magnet configurations covering a practical range of magnet dimensions. A comparison of machine performance predicted using this method with test results is also given.     

参数优化支持向量机的密封电子设备多余物定位方法研究

在密封电子设备的生产制造过程中,对多余物进行检测和定位至关重要。 针对设备体积大和多余物位置难以确定的问 题,使用参数优化支持向量机对设备内部的多余物进行定位。 通过设计信号调理电路与多通道信号同步采集电路,调理和采集 微弱的多余物信号,设计两级双门限脉冲提取算法和多通道脉冲匹配算法对信号进行预处理,得到有效的信号数据。 提取和选 择性能优良的时频域特征构建定位数据集,比较不同分类算法在数据集上的性能表现,对更优的支持向量机进行参数优化设 计,将优化后的支持向量机定位模型用于实物测试。 测试结果表明,参数优化支持向量机的定位模型在航天电源内部的多余物 定位测试的平均精度达 82. 58%,定位模型的泛化能力良好,达到航天系统工程的精度要求,该方法理论上可以推广应用于类似 产生机理的碰撞信号定位。     

Rotor Chopper Control for Induction Motor Drive: TRC Strategy

A solid-state induction motor speed regulating scheme using a rotor chopper-controlled external resistor is investigated. This control scheme provides continuous and contactless variation of rotor resistance and thereby eliminates the undesirable features of the conventional rotor resistance control method. A thorough analysis of the steady-state performance of the system is presented. Both dc and ac circuit models are derived to describe the performance characteristics when the chopper operates under the time-ratio control (TRC) strategy. Effects of machine parameters on performance characteristics are studied. Theoretical results from the model are verified by comparison with experimental results. The torque?speed characteristic of this speed control system is essentially linear for a particular time ratio.     

Estimation of synchronous machine parameters from performance relations

The parameters of synchronous machines are required in system analysis, fault calculations, sizing of cables, circuit breaker selection, power factor correction, and voltage drop calculations. One of the major stumbling blocks is the general lack of design and application data. The design information is generally restricted and not commonly available to all users. Furthermore, the parameters are difficult to obtain through field measurements. In this paper, a mathematical model is presented to estimate the parameters of a synchronous machine from name-plate details. The data used in the estimation include output kVA, voltage, current, speed, rated power factor, field voltage, field current, and short-circuit ratio. The equations are derived from a well-known performance model and solved using a spreadsheet program available on any personal computer. Two case studies are presented in this paper. There is reasonable agreement between the estimated and available parameter values. Finally, the usefulness of this procedure and some of the limitations are outlined.     

Comparative study of 3-D flux electrical machines with soft magnetic composite cores

This paper compares two types of three-dimensional (3-D) flux electrical machines with soft magnetic composite (SMC) cores, namely, claw-pole and transverse-flux machines. 3-D electromagnetic field analysis is conducted for the computation of some important parameters and optimization of the machine structures. An equivalent electric circuit is derived to calculate the machine performance. The analysis methods are validated by experimental results of a single-phase claw-pole permanent-magnet machine with an SMC core. Useful conclusions are drawn from the evaluation and comparison of two machines with SMC cores.     

A method for wide frequency range modeling of power transformersand rotating machines

Wide frequency range representation of power system components such as power transformers, reactors and rotating machines is mainly needed for the analysis of electromagnetic transients in power systems. In this paper, a method is presented for state space formulation of machine windings. The described procedure is completely based on external terminal impedance measurements and data related to the internal structure is not required. First, the wide frequency behavior of machine windings is reviewed and the nonlinearity effects of the iron core are discussed. A numerical method is given for calculation of the state equation parameters directly from the measured terminal impedance characteristics. The presented modeling method is applicable to any transformer, reactor or rotating machine in service where sufficient information on the internal design is not available. Besides, the canonical structure of the model offers advantages in terms of computer memory and computation effort in time domain analyses of complex power systems     

Estimation of induction motor parameters using shuffled frog-leaping algorithm

This paper introduces a shuffled frog-leaping algorithm based method to approximate the equivalent circuit parameters of induction machines from the manufacturer data, such as nameplate data and motor performance characteristics. The steady-state equivalent circuit is applied for the simulations. The circuit parameters are found as the result for the error minimization function between the estimated and maker data. The suggested algorithm solves the parameter estimation problem and surpasses the solutions reached by differential evolution, particle swarm optimization and genetic algorithms. Therefore, this algorithm can be employed in motor energy management system for bettering the overall energy savings in industry.