Characteristic Analysis of Multilayer-Buried Magnet Synchronous Motor Using Fixed Permeability Method

The direct (d)- and quadrature (q)-axis inductance characteristics of the interior permanent-magnet synchronous motor (IPMSM) are presented, with an emphasis on the cross-coupling effects. Nonlinear variation of phase inductance is investigated, according to the rotor position on entire stator current excitations. We also propose a new analytical method, called the fixed permeability method (FPM). We applied this method (FPM) to steel-cored permanent-magnet linear synchronous motors for large powered linear motional applications. Experimental data were found to corroborate the findings obtained by the FPM method. We also used FPM to analyze magnetic saturation characteristics of the prototype IPMSM, and compared the air-gap flux density and$d$- and$q$-axis inductance with the conventional finite element analysis results.     

Modeling and simulation of saturated induction motors in phasequantities

This paper proposes a new model for saturated induction motors. The saturation effects are incorporated in the magnetizing inductance and the stator mutual inductances, taking into account the nonuniform distribution of magnetic saturation within the motor core. The proposed model can be used to analyze the manner in which the induction motors interact with the supply network or power source, since it can predict the motor current/voltage harmonics produced by magnetic saturation. Experimental tests show that the proposed model represents with reasonable accuracy (8%) the motor saturation effects at nominal stator voltage as well as for overvoltage operation     

Induction motor dynamic and static inductance identification usinga broadband excitation technique

The performance of indirect vector control depends upon accurate prediction of the motor slip angular frequency (ω_s) for the demand torque. The required slip gain depends upon the rotor time constant of the motor (T_r). This value varies significantly over the operating temperature range and saturation level of a typical motor. This variation, if not compensated for, results in a significant degradation in torque production from a vector control system. The saturation effect can be compensated by an adaptive flux model if precise knowledge of the induction motor magnetizing curve is available. The aim of this paper is to present the application of an advanced system identification methodology enabling the off-line estimation of the magnetizing curve (dynamic and static inductance) of induction motors     

Coupled finite-element/state-space modeling of turbogenerators inthe abc frame of reference-the no-load case

This first of two companion papers centers on applying a coupled finite-element/state-space technique to the determination of self and mutual winding inductances of a 733 MVA turbogenerator and computing its open-circuit characteristic, in the natural abc frame of reference. In this method, the apparent self and mutual inductance profiles of the armature and field windings, expressed as functions of rotor position angle, are computed from a series of magnetic field solutions performed at uniformly-distributed samples of rotor positions covering the entire 360° electrical cycle, using the energy perturbation method. These inductances, which are obtained at no-load for three different excitation levels, include the full effect of space harmonics introduced by the magnetic circuit geometry, winding layouts and magnetic circuit saturation. The abc-frame/finite-element computed open-circuit characteristic is in excellent agreement with the test results. This computed no-load set of parameters forms the initial data for simulation of the full-load performance given in the companion paper, including the full impact of space harmonics and saturation on the flux linkage, current and voltage waveforms, and other performance parameters     

复励式消弧线圈的研究及应用

提出一种快速复励式偏磁消弧线圈,简要介绍了其结构和控制原理。描述了新型消弧线圈的励磁系统数字控制系统,通过最新的DSP FPGA组合控制实现了消弧线圈快速补偿。仿真计算及试验对比分析表明,新型消弧线圈具有优良的特性。     

Experimental Characterization Procedure for a Synchronous Machine Model With Saturation and Arbitrary Rotor Network Representation

This paper sets forth the experimental procedure for obtaining the parameter set of a synchronous machine model with saturation and arbitrary linear network representation for the rotor. The method utilizes a combination of magnetization curves and standstill frequency-response tests. A novel test procedure is proposed for obtaining the turns ratio. The rotor's transfer function and stator leakage inductance are extracted from the frequency response using genetic algorithms.     

Estimation of a global synchronous machine model using a multiple-input multiple-output estimator

In this paper, the measurement results of a series of standstill frequency-response (SSFR) tests, performed at different magnetization levels, are discussed. For each data set, an individual d-axis model is estimated, which allows seeing the variation of the different parameters as a function of saturation. A global estimator is presented which uses the different data sets to estimate one global model, including the field-to-armature turns ratio. The global estimator is based on an impedance matrix representation of the synchronous machine. This global estimator assumes that only the d-axis main inductance is saturation dependent. The individual estimated models justify this assumption. Finally, the relative additional error of the global estimated d-axis equivalent circuit with the individual estimated ones is studied. The measurement results discussed in this paper are obtained on a four-pole 130-kVA synchronous machine.     

A technique for the steady-state analysis of a self-excitedinduction generator with variable speed

A method to analyze the steady-state open loop behaviour of a self-excited induction generator with an unregulated prime mover is presented. The proposed method needs little mathematical effort and does not require an assumption about the generator speed. The proposed approach based on nodal analysis allows one to use arbitrary functions for the torque-speed characteristic of the prime mover and for the saturation of the magnetizing inductance without complicating the solution process. It always leads to a single equation for the frequency. An example is presented demonstrating the advantages of the proposed method. The analytical results are verified by measurements     

三相电孤炉相间功率转移与电感补偿研究

首先对功率转移与不对称电流的关系作了理论分析，然后推导得到了电弧功率与短网参数的关系式。指出了中相补偿器是消除功率转移危害，解决三相电弧功率平衡的有效方法。从理论上明确了对于三相电弧炉，最多不超过两个补偿电感就可以保证三相电弧功率平衡。给出的补偿电感计算公式，充分考虑了各相自感的差别。是文献［１］计算公式的修止和补充。最后给出了中相补偿器的实际使用效果。     

Model of the commutation phenomena in a universal motor

An equivalent electrical circuit, characterized by the minimum coil sections number necessary to analyze the commutation in a universal motor, is discovered. The model parameters are also determined: in particular, the self and mutual inductance coefficients and the electromotive force induced in the coil sections (taking into account the magnetic saturation), the brush-commutator voltage drop, the electric arc. By means of a numerical solution of the equivalent circuit, the current waveforms are analyzed; the comparison between the computed and measured waveforms of the brush-commutator voltage drops allows to verify the model.     

基于ANFIS-PI的同步磁阻电机矢量控制

针对同步磁阻电机在正常运行过程中磁路饱和导致的电感变化问题,提出一种采用自适应神经模糊推理系统(ANFIS)的PI参数整定方法,以提高电机控制的响应速度。先采用电流调节系统对样机有限元模型进行仿真,得到电流电感数据并拟合电感表达式,进而计算最大转矩电流比的电流角,然后搭建了基于ANFIS-PI的同步磁阻电机矢量控制模型,将经过神经网络训练后的控制模型与有限元软件进行联合仿真。结果表明,与常规PI控制相比,采用ANFIS-PI法可更准确地调整PI参数,进而提高电机动态响应速度。     

Axial Field Permanent Magnet DC Motor With Powder Iron Armature

The paper describes a double-gap axial field permanent magnet (PM) dc motor whose double-layer armature wave winding is constructed of copper strips. It investigates the performance of two machines using powder iron and lamination steel materials as armature teeth. Tests are conducted to evaluate the motor torque and speed curves as well as their efficiency under different loads. Finite element analysis (FEA) and equivalent circuit models are used to determine the levels of the magnetic saturation in the motors; calculate torque, inductance, and electromotive force (EMF); and determine the distribution of losses in the machine. The results show that the powder iron armature machine has lower back EMF and torque constants, and is less efficient than the steel laminations machine, which is due to the lower permeability and saturation flux density of the powder iron material.     

Neural network-based modeling and parameter identification of switched reluctance motors

Phase windings of switched reluctance machines are modeled by a nonlinear inductance and a resistance that can be estimated from standstill test data. During online operation, the model structures and parameters of SRMs may differ from the standstill ones because of saturation and losses, especially at high current. To model this effect, a damper winding is added into the model structure. This paper proposes an application of artificial neural network to identify the nonlinear model of SRMs from operating data. A two-layer recurrent neural network has been adopted here to estimate the damper currents from phase voltage, phase current, rotor position, and rotor speed. Then, the damper parameters can be identified using maximum likelihood estimation techniques. Finally, the new model and parameters are validated from operating data.     

High-speed performance improvements of a two-phase switched reluctance machine utilizing rotor-conducting screens

The two-phase 4/2 switched reluctance machine is suitable for high-speed operation. It has a simple and robust construction and can be operate from power converters that have no shoot-through mode. In this paper, conducting screens are incorporated in the rotor of a prototype 400 W, 7500 rpm two-phase switched reluctance machine. The effect of the conducting screens on current response, output torque, output power and efficiency of the machine are experimentally evaluated and explained. The conducting screens improve the torque at higher speeds, increase the output power and improve drive efficiency. At low speeds, the conducting screens improve rate of change of inductance and hence torque. At high speeds, enhancements in performance are due to a lowered unaligned inductance that provides an improved initial current response. At rotor speeds greater than base speed and below a breakpoint speed it is found that the conducting screens are detrimental to the performance of the machine. A reason for this phenomenon is given.     

Turbogenerator end-winding leakage inductance calculation using a 3-D analytical approach based on the solution of Neumann Integrals

An analytical technique that can be effectively used for the calculation of the end-winding leakage inductance of a turbogenerator has been presented. It is based on a three-dimensional geometric model of the end-winding region in which each coil is modeled as a set of serially connected straight filaments. The calculation of the mutual inductance of the end coils is based on the multiple solutions of the Neumann integral. The method also accounts for the influence of stator core iron on the end-winding leakage inductance by using the method of images. The results of the calculations have been compared with the measured values of the leakage inductance for 247-MVA turbogenerator manufactured by KONCAR Generators and Motors Inc., Zagreb, Croatia. The principle of the end-winding leakage inductance calculation described herein can be effectively used for other types of machines and windings as well.     

Online identification of the mutual inductance for vector controlled induction motor drives

Mutual inductance of an induction machine may vary considerably when the flux reference varies. An important and frequent application of a variable flux reference is the operation in the field-weakening region. Standard assumption of constant mutual inductance is no longer valid and it becomes necessary to compensate for the mutual inductance variation. The paper proposes a novel method for online mutual inductance identification in vector controlled induction machines. The method is characterized with very simple structure, ease of implementation, very low parameter sensitivity, and capability to provide an accurate estimate under both transient and steady state operating conditions. Full experimental verification of the proposed scheme is provided and a number of potential applications in a vector controlled induction motor drive are discussed.     

多孔介质中甲烷水合物的微观分布对电阻率的影响

电阻率测井技术是天然气水合物储层资源量估算的重要手段,明确储层电阻率与水合物在沉积物孔隙中微观分布的关系对准确估算水合物饱和度有重要意义。使用自主研发的天然气水合物计算机断层扫描（CT）技术-电阻率测量装置,开展多孔介质中甲烷水合物生成实验,同时进行CT观测与电阻率测试,得到了反应过程中扫描图像和电阻率数据,讨论了孔隙中水合物在不同微观分布模式下电阻率与水合物饱和度的关系。结果表明：水合物饱和度低于10.50%时,水合物以接触分布模式为主,与水合物对孔隙的填充效应相比,排盐效应更加显著,电阻率随水合物饱和度增大略有下降;水合物饱和度为10.50% ~ 22.34%时,水合物为悬浮与接触共存分布模式,悬浮分布模式下的水合物对孔隙水连通截面的阻塞作用较大,电阻率随水合物饱和度的增大急剧升高;水合物饱和度为22.34% ~ 27.50%时,水合物仍然为悬浮与接触共存分布模式,在大部分孔隙已被堵塞的情况下水合物的填充作用对电阻率影响较小,电阻率随水合物饱和度增大而升高的趋势逐渐变缓。可见,电阻率响应特性在不同的水合物饱和度范围下明显不同,与水合物的微观分布有关。     

特高压直流输电系统馈入的城市电网谐波渗透特性分析

针对城市电网直流输电落点谐波从高电压等级向低电压等级渗透过程中出现的高次谐波放大现象,基于网络固有结构理论,提出一种城市电网谐波放大分析方法。注意到电缆对谐波跨电压等级渗透的影响,在谐波国标框架下按等效注入谐波电流大小评价其影响,提出等效注入感容耦合度评估其影响机理,并建立电缆分布参数模型,对其系统等值阻抗感容临界条件进行分析。利用多直流落点局部城市电网对所提方法进行分析验证,并与现场测量数据对比,结果表明所提方法能有效判别谐波敏感回路,以及分析电缆对谐波渗透的影响机理。     

Static characteristics of a new doubly salient permanent magnetmotor

In this paper, magnetic field analysis of a new doubly salient permanent magnet (DSPM) motor is carried out based on the finite element method (FEM). Hence, the corresponding static characteristics, including PM flux linkage, self-inductance, mutual inductance, and static torque are deduced (the interaction between the PM field and armature field are taken into account). New methods for measuring the motor inductance are also proposed. The theoretical analysis is verified by experimental results