Axially Laminated Anisotropic Research Articles

Impact of the Current Vector Angle on the Performance of a Synchronous Reluctance Motor With an Axially Laminated Anisotropic Rotor

The impact of the current vector angle on the performance of a synchronous reluctance motor (SynRM) with an axially laminated anisotropic (ALA) rotor intended for high-speed applications is studied. The paper shows that the current vector angle not only impacts on the stator winding Joule losses and iron losses, but also strongly influences eddy current losses in the rotor (when the rated torque is produced). The rotor eddy current losses are determined by the flux density harmonics produced by the stator. The air gap flux is affected both by the magnitude and angle of the current vector. However, the rotor surface harmonics are not directly related to the overall flux level (which can be quite low at a high current angle) but depend more on the values of the individual slot current linkages. Considering the dependence of rotor losses on the current vector angle, the most efficient operating point is suggested to be close to 45° or slightly larger, up to 65°, where a compromise between increasing rotor eddy current losses and winding Joule losses and decreasing stator iron losses is found. The eddy current loss distribution between the layers of an ALA rotor is analyzed in detail. With a larger current vector angle, the eddy current losses increase most in the layers close to the d-axis. This is explained by the largest current linkage in the stator slots that are in front of the layers close to the d-axis. The dependence of torque ripple on the current vector angle is also observed. An analysis of rotor and stator high-order harmonics, which determine the torque ripple, is performed.

Influence of Magnetic and Nonmagnetic Layers in an Axially Laminated Anisotropic Rotor of a High-Speed Synchronous Reluctance Motor Including Manufacturing Aspects

The impact of the thickness of the magnetic and nonmagnetic layers in an axially laminated anisotropic (ALA) rotor in a synchronous reluctance motor (SynRM) aimed at high-speed applications was studied. Considering possible manufacturing issues, the layers are desired to be thick rather than thin. At the same time, the layer thickness is related to the electromagnetic capabilities of the ALASynRM. In the study, a 12 kW ALASynRM was considered. As a reference, a 12 kW IM with a smooth solid rotor with copper end rings was used for comparison with the designed ALASynRM. The manufacturing procedures of an ALA rotor with certain materials were verified in practice. Strength tests of the samples were implemented showing the suitability of the selected materials for application in the prototype. In the electromagnetic design, the thickness of the ALA rotor layers has shown to have a significant impact on the rotor eddy current losses. The stator iron losses and the winding Joule losses also depend on the rotor design. Torque ripple is considerably affected by the thickness of the rotor layers and their position in relation to the stator slots.

Third-Order Harmonics in Synchronous Reluctance Motors With an Axially Laminated Anisotropic Rotor and Their Impact on the Motor Losses

The phenomenon of third-order harmonics in synchronous reluctance motors (SynRMs) with an axially laminated anisotropic (ALA) rotor is studied. The paper shows that a specific rotor geometry can distort the air-gap flux density and induce third-order currents in the stator winding if it is delta connected. The third-order currents in different phases have the same phase shift angle and cannot, therefore, produce a rotating air-gap flux. Instead, they produce an air-gap flux that pulsates in time, and thus, causes eddy current losses in the rotor conducting parts. The phenomenon was described and proven with finite element simulation (FEM) of a 12 kW high-speed ALASynRM. The research underlines the importance of considering the third harmonic phenomenon in the design of a two-pole ALASynRM intended for high-speed applications, where a specific rotor geometry with a wide magnetically conducting middle layer is required.

Optimum design criteria of an ALA-SynRM for the maximum torque density and power factor improvement

This paper covers the characteristic analysis and optimum design of an axially laminated anisotropic (ALA) type Synchronous Reluctance Motor (SynRM) using a coupled Finite Element Method (FEM) and Response Surface Methodology (RSM). The rotor core of an ALA type adheres to the shaft axis, which has higher torque characteristics and a higher power factor due to the large difference of the (Ld-Lq) and (Ld/Lq) ratio. However, this assembly structure is affected by the centrifugal force around the shaft axis. This paper covers the study of an ALA-type rotor to solve this problem. Therefore, by simulating the structure and the electromagnetic field, it is confirmed that the width of rotor core and insulator is set to design variables to reduce the minimum loss and the centrifugal force. Finally, comparisons are given with the characteristics of a same rated wattage traction induction motor and those of an ALA-SynRM, respectively.

Self-Excited Reluctance Generator: State of the Art and Future Trends

This paper is a road map for the new generation of graduate students who are interested in reluctance generator research work. Recent research work on two-pole single phase self-excited reluctance generator (2PSPSERG) has been evaluated. The coverage extends over three decades of time, and covers more than eighty pages of reported pioneering research work. Topics addressed include: converting synchronous motor into reluctance generator (RG), types of rotors used especially axially laminated anisotropic (ALA), existence of mutual coupling, negative mutual coupling, time variation of windings inductances, d-axis and q-axis inductance variations with flux, rotor saliency ratio variation with flux, relationship between electrical frequency of stator windings voltages and currents and rotor mechanical frequency of rotation, unbalanced loading of RG, stability of RG under rotor speed fluctuations, stability of RG under load power factor changes, and efficiency of RG. Findings extracted from literature-cited matrix are reported, as well as gaps revealed by the same matrix. Facts in SERG literature are collected and listed. Questions raised during the study are documented. Guidelines for clear experimental future research work are outlined. Finally, suggestions for future research are then discussed.

축 방향 성층 이방성 동기형 릴럭턴스 전동기의 최적설계 및 유도전동기와의 특성 비교

The performance of a Synchronous Reluctance Motor (SynRM) in terms of torque and power factor depends on the two-axis inductances L<SUB>d</SUB> and L<SUB>q</SUB> of the machine. The Axially Laminated Anisotropic (ALA) rotor should be proposed in an effort to increase the L<SUB>d</SUB>/ L<SUB>q</SUB>ratio and the L<SUB>d</SUB>-L<SUB>q</SUB> difference to secure high torque density and high power factor. So, ALA rotor is suitable for high speed instruments. This paper deals with optimum design of Axially Laminated Anisotropic Synchronous Reluctance Motor (ALA-SynRM) and comparison of characteristics with induction motor. Coupled Finite Element Methodology (FEM) & Response Surface Methodology (RSM) have been used to evaluate optimum design solutions. Comparisons are given with characteristics of a same rated wattage induction motor and those of ALA-SynRM respectively.

Research on Operating Performance for Hybrid Rotor Synchronous Motor

This paper with an open-loop V/f control mode of inverter supply, searched for the causes of the oscillation using small signal analysison the axially-laminated anisotropic (ALA) rotor and hybrid rotor (ALA-SPM two-part) motor, and analyzed operating performance of themotors with inertial damper on the same shaft. Results show that the negative electromagnet damping coefficient can be the key point toresult in the oscillation; the electromagnet damping coefficient can increase with the increasing new variable k, the fraction length of SPMpart, the maximum load of the motors and the stability can be improved. The stability of the system and the dynamic performance can bebetter with reasonable viscous damping coefficient of inertial damper, the motors can adequately develop their output torque capability,and improve operating performance. Ill. 11, bibl. 11, tabl. 3 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.113.7.603

Particle Swarm Design Optimization of ALA Rotor SynRM for Traction Applications

Particle swarm optimization (PSO) algorithm is applied to the design optimization problem of axially laminated anisotropic (ALA) rotor synchronous reluctance motor (SynRM) drive. The objective of the optimization is to maximize the developed torque while minimizing the torque ripple as well as the ohmic and core losses for traction applications. The number of flux paths, stator tooth width, and rotor flux path width define the 3-D search space for the optimization problem. An artificial intelligence modeling approach utilizing PSO and finite element-state space (FE-SS) models is used for the characterization and design optimization of a prototype ALA rotor SynRM drive for traction applications.

Design Optimization of ALA Rotor SynRM Drives Using T-AI-EM Environment

An integrated team artificial-intelligence electromagnetic (T-AI-EM) environment is developed to accurately determine the performance of synchronous reluctance motors (SynRM) with axially laminated anisotropic (ALA) rotor configurations. This identifier coupled to a Fuzzy Logic optimization model is used to predict an optimal design of the machine for any given input torque. The main objective of this optimization is to minimize the torque ripple, as well as Ohmic and core losses at a given torque-speed condition. This environment is applied for the characterization and design optimization of a prototype 100-kW, 6000-rev/min ALA Rotor SynRM drive system for traction applications. The T-AI-EM environment resulted in an optimized machine design. The simulation results were compared to measured performance data for verification

Parameter and performance comparison of doubly fed brushless machine with cage and reluctance rotors

The cage and reluctance rotors are two main types of rotor structure used in doubly-fed brushless machine (DFBM). In order to study comparatively the effect of different rotor structure on the behavior of DFBM, a prototype machine has been specially designed and built. The experimental parameter and performance comparisons between the axially laminated anisotropic (ALA) reluctance rotor and cage rotor machine are presented in the paper. It is indicated that the cage rotor DPBM has relatively better starting and asynchronous characteristics, however, the ALA reluctance rotor DFB exhibits fine synchronous operation and doubly-fed adjustable speed performances.

Parameters evaluation of ALA synchronous reluctance motor drives

A method to evaluate the parameters and to predict the performance characteristics of axially laminated anisotropic (ALA) rotor synchronous reluctance motor (SynRM) drive systems is presented. The method is based on the use of an iterative approach which indirectly couples a two dimensional (2D) nonlinear finite element (FE) model, which accounts for anisotropy, to a state space model describing the SynRM drive system. At the heart of this method is an inductance computation technique which is based on the use of a reluctivity tensor. The results of applying this approach to a prototype ALA rotor SynRM drive system are presented.

Effects of converter excitation on the performance of axially laminated anisotropic synchronous reluctance motor drives

An indirectly coupled state space-finite element (ICSS-FE) model of axially laminated anisotropic (ALA) synchronous reluctance motor (SynRM) drive systems is used to evaluate the impact of converter excitation on the machine performance characteristics. The model utilizes an iterative approach which includes the full impact of nonlinearities on the machine magnetic circuit, and which results in the nonsinusoidal flux waveforms in the different parts of the machine. The modeling approach is applied to a prototype ALA SynRM designed for use in hybrid vehicle applications.

Computer aided models for the characterization of synchronous reluctance motor drive systems

A computer aided model based on the use of an indirect coupled and iterative approach is used to predict the performance characteristics of synchronous reluctance motor (SynRM) drives. The approach indirectly couples a two dimensional (2D) nonlinear finite element (FE) model, which accounts for magnetic saturation and space harmonics, to a time variant state space model describing the SynRM drive system. The effects of various modes of excitation on the axially laminated anisotropic (ALA) rotor synchronous reluctance motor (SynRM) drive systems performance characteristics are studied.

Characterization of axially laminated anisotropic-rotor synchronous reluctance motors

The effects of accounting for anisotropy on the energy performance characteristics of the axially laminated anisotropic (ALA) rotor synchronous reluctance motor (SynRM) are presented. These effects are evaluated from the simulation of indirectly coupled magnetic field-electric circuit models which fully account for magnetic saturation and space harmonics, to a time variant state space model describing the SynRM drive system. Furthermore, the simulation method fully accounts for strong material and structural anisotropy exhibited in the curved flux barrier regions of the rotor ALA-rotor SynRM. The simulation results are validated by direct measurement of inductances and energy conversion performance of a 100 kW prototype ALA-rotor synchronous reluctance machine.

Effects of anisotropy on the performance characteristics of an axially laminated anisotropic-rotor synchronous reluctance motor drive system

The effects of accounting for anisotropy on the performance characteristics of axially laminated anisotropic (ALA) rotor synchronous reluctance motor (SynRM) drive systems are studied. These effects are evaluated from the simulations of a computer aided model. The model is based on the use of an iterative approach which indirectly couples a two dimensional (2D) nonlinear finite element (FE) model, which accounts for anisotropy, to a state space model describing the SynRM drive system. The simulation results are also validated by comparison to test data of a prototype ALA rotor SynRM drive system.

Magnetic field and core loss evaluation of ALA-motor synchronous reluctance machines taking into account material anisotropy

Currently, much attention is paid to the behavior of thin laminations of anisotropic soft magnetic materials with respect to magnetization out of the easy axis. A method for analyzing flux distribution and loss calculation is proposed for electric machines exhibiting strong material and 'structural' anisotropy. The method takes into account the curvature in anisotropic and composite flux barrier regions by introducing equivalent reluctivities. The results of a case study on an axially laminated anisotropic (ALA) rotor of a synchronous reluctance motor (SynRM) are presented.

Anisotropic finite element computation of high density axially-laminated rotor reluctance machine

Nonlinear and anisotropic magnetic fields in a high density Axially-Laminated Anisotropic (ALA) rotor reluctance machine are computed by the finite element method. Different position angles between stator current vector and rotor d-axis (from 0/spl deg/ to 90/spl deg/), different pole span lengths (from 2/3 pitch to full pitch) and different applied currents (from 0 to 2 times the rated value) are investigated. Based on numerical results, the parameters and performance of this machine are calculated and discussed. Conclusions show that in order to achieve linear parameters and high performance, the per unit value of the magnetizing current should be less than 0.5 and the pole span length should be optimized.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Performance evaluation of axially-laminated anisotropic (ALA) rotor reluctance synchronous motors

Performance evaluation of axially-laminated anisotropic (ALA) rotor reluctance synchronous motors

High-performance reluctance generator

The paper introduces the axially laminated anisotropic (ALA) rotor reluctance synchronous machine as a brushless high-performance generator. A new theory for steadystate performance analysis and determination of maximum power-conversion capability of reluctance generators is presented. The high efficiency, high power factor, and high power density of the ALA-rotor reluctance generator are demonstrated through load tests on a laboratory model obtained from a 1.5 kW, 2-pole induction machine whose rotor was replaced by a single lamination/insulation-layer ALA rotor built for demonstration purposes. Unusually high values of Ld/LL ratio have been measured (Ld/Lq &gt; 16). The reluctance generator should be ideal as a DC-output brushless generator, with power electronics for voltage control.

Digital Simulation Of A Vector Current Controlled Axially-Laminated Anisotropic (ALA) Rotor Synchronous Motor Servo-Drive

ABSTRACT It has been recently demonstrated that axially laminated anisotropic (ALA) rotor reluctance motors have high torque density, power factor and efficiency due to unusually high Ld/Lq ratios. For variable-speed vector-controlled drives no starting cage on the rotor is required. Through digital simulations this paper explores the steady-state torque and power factor capabilities and the transient performance of a vector ac current-controlled ALA-rotor motor drive. Fast torque and speed responses are demonstrated for a two-pole motor up to a speed of 2500 rpm. Good performance down to 0.1 rpm is obtained through an adaptive proportional integral (PI) speed controller.