永磁电机研究的新进展(英文)

This paper overviews advances on permanent magnet(PM) brushless machines over last 30 years,with particular reference to new and novel machine topologies.These include current states and trends for surface-mounted and interior PM machines,electrically and mechanically adjusted variable flux PM machines including memory machine,hybrid PM machines which uniquely integrate PM technology into induction machines,switched and synchronous reluctance machines and wound field machines,Halbach PM machines,dual-rotor PM machines,and magnetically geared PM machines,etc.The paper highlights their features and applications to various market sectors.     

Performance of PM-assisted synchronous reluctance motor forhigh-efficiency and wide constant-power operation

This paper examines the design and the performances of a permanent-magnet assisted synchronous reluctance motor (PMASRM) for wide constant-power operation. The effects of properly adding magnets into the rotor of a synchronous reluctance motor are examined by several experimental results and analyses on the prototype machines. The proposed machine can offer a large constant-power speed range, high-efficiency and high-power-factor operation in comparison to the complete synchronous reluctance motor. It was shown that the problems such as the decrease of efficiency at light-loads and the uncontrolled generator mode operation, which occur in the high-speed flux-weakening operation of the conventional PM motor drives, can be eliminated in the PM-assisted synchronous reluctance motor     

Prediction of the electromagnetic torque in synchronous machines through Maxwell stress harmonic filter (HFT) method

For the calculation of torque in synchronous motors a local method is analysed, based on the Maxwell stress theory and the filtered contributions due to the harmonics of the magnetic vector potential in the motor air-gap. By considering the space fundamental field only, the method can efficiently estimate the average synchronous torque for a variety or motor topologies, including concentrated winding designs. This approach employs an analytical filter for the Maxwell stress tensor and `frozen permeability' technique. The proposed method is validated by comparison with FE results for several synchronous motor types: interior permanent magnet motors, wound field motor, synchronous reluctance motor.     

永磁同步电动机瞬态场的有限元动态分析

稀土永磁同步电动机从某一运行状态突然到另一运行状态的过渡过程中,有可能引起严重后果。首先要准确细致地分析电机内部瞬态磁场的分布,然后才可以方便地计算电机的瞬态特性。本文采用电流偶合法,对凸极转子进行了新型自动剖分,建立了恒定电压源激励下均匀媒质非线性通用形式的时步有限元差分方程,计算结果与实验结果比较,表明该方法是计算和分析永磁同步电动机的一种有效的方法,也是设计永磁同步电动机的有效途径。     

Axial flux interior PM synchronous motor: parameters identification and steady-state performance measurements

This paper presents different measurement and identification approaches applied to a nonconventional permanent-magnet (PM) synchronous machine, namely, the novel axial flux interior PM (AFIPM) synchronous motor. The nonconventional geometry of the AFIPM motor requires a dedicated discussion on the parameter identification subject. In the paper, the standstill frequency-response test and the standstill time-response test on the AFIPM prototype are presented. On the basis of these tests, the d- and q-axes circuit parameters are chosen. To confirm the validity of the standstill tests, the load tests have also been performed. Furthermore, the load tests provide some preliminary AFIPM machine performance results and additional information on the saturation phenomena. The d- and q-axes equivalent circuits parameters obtained by the performed measurements are analyzed and compared. Finally, the most appropriate AFIPM machine model is selected.     

Field-weakening performance of interior permanent-magnet motors

This paper compares the field-weakening performance under rated and overload conditions of synchronous reluctance and interior permanent-magnet motors against that of a baseline 2.2-kW induction machine. Four prototype rotors based on axially laminated and multiple-barrier designs were built and tested in the same induction machine stator. Field-weakening performance was estimated based on 50-Hz load tests at reduced voltage. It was found that the performance of the axially laminated synchronous reluctance machine was comparable with the induction machine while the interior permanent-magnet motors offered significantly better output power above rated speed. The multiple-barrier interior permanent-magnet motor design gave the most promising field-weakening performance.     

Magnet shape optimization of five‐phase surface‐mounted permanent magnet machine to improve torque performance based on equivalent permanent magnet method

This paper studies the magnet shape optimization of a five‐phase surface‐mounted permanent magnet (PM) machine to improve its torque performance. First, a sinusoidal PM with third and fifth harmonics (sine + third + fifth PM) is presented to enhance the torque. An equivalent PM method is then proposed to avoid the complicated interface conditions between PM and the air gap, making the derivation of torques with magnet shapes using 2‐D analytical models possible. Besides, the influence of PM edge thickness on torque improvement is considered. Moreover, under the condition that the copper losses of machines with different magnet shapes are kept unchanged, optimal harmonics of sinusoidal PM with third harmonic (sine + third PM) and sine + third + fifth PM are analytically derived. Finite element (FE) analysis is performed to validate the equivalent PM method and analytical results. Finally, machines with sine + third PM, sine + third + fifth PM and conventional (without shaping) PM are comparatively studied using nonlinear FE analysis and the experimental results of machine with sine + third + fifth PM are presented, verifying the effectiveness of the analytical optimization of magnet shape. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

ANALYSIS OF THE INTERFERENCE SYNCHRONOUS MACHINE

ABSTRACT

Interference synchronous machines operate at different speeds of the fundamental air gap field and of the rotor, because the fundamental permeance wave is produced by interference of open stator and rotor slots the numbers of which being slightly different. In the literature different names are used for this remarkable electrical machine (“Synchronous inductor motor”, “Vernier reluctance motor”). Interference synchronous machines are used as homopolar frequency generators with an axial field coil, as continuous running reluctance motors and as single- or double, - stack step motors with an axial permanent magnet.

In this paper the field of the interference synchronous machine is analysed by field wave theory. Speed,phase angle and length of the largest field waves reveal how synchronous and cogging torques are produced. Voltage and torque equations are derived by axis theory from the simplest model that is possible with five rotor teeth. The theory is applied on a fifty rotor teeth double-stack step motor. The inductances are determined by a difference method field calculation. The torque of the motor is then calculated and compared with measured values.     

Emerging Electric Machines with Axially Laminated Anisotropic Rotors: A Review

ABSTRACT

This paper presents a class of multiphase electric machines with axially laminated anisotropic (ALA( passive rotors. Unipolar, two-level bipolar, and sinusoidal current modes are identified. The reluctance variation in ALA rotor is computed for a wide range of airgaps and pole pitches. High ratios of inductances along d and q axes yield high torque densities. Special attention is paid to the sinusoidal current mode through a quantitative comparison with the induction and PM synchronous counterparts with the same stator. It is demonstrated that the ALA rotor sinusoidal current synchronous motor is superior in all respects to the induction motor and almost equals the performance (torque density, efficiency, power factor( the PM synchronous motor.     

EFFECT OF PARAMETER VARIATIONS ON THE STABILITY LIMITS OF PERMANENT MAGNET SYNCHRONOUS MACHINES

ABSTRACT

This paper presents a comprehensive study of the effect of parameter variations on the stability behavior of permanent magnet (PM) machines. The state-variable equations are derived in terms of a set of non-dimensional parameters, so that their effects on the stability limits can be simply demonstrated. The stability is analyzed by means of state- space technique as it has the advantages of simplicity, accuracy and flexibility. The results of the analysis allow a choice of necessary and sufficient conditions for stable operation of the machine. The results also look interesting from a practical point of view, since a more realistic and efficient margin for stability limits can be defined. Simulation results are obtained using parameters of a 25-hp PM synchronous motor provided with a Neomax-35 magnets for excitation. Finally, useful conclusions have been provided, which are considered to be a good aid for designing these machines.     

Cogging Torque Reduction in an Axial Flux PM Machine via Stator Slot Displacement and Skewing

Cogging torque is a source of vibration and noise in permanent-magnet (PM) machines. This torque is proportional to the PM flux and the reluctance variation, and is independent of the load current. In this paper, two methods for cogging torque reduction in an axial PM machine with field weakening capability are presented. The machine's rotor configuration considers two sections: one PM pole that provides the field excitation and one iron section in charge of providing low d-axis reluctance. Significant reduction of the cogging effects is achieved by adjusting stator geometry and rotor pole configuration. Three-dimensional finite-element analysis is used to demonstrate these improvements. Conclusions and design recommendations are presented for a 5-kW eight-pole PM machine prototype under construction     

Controller-induced parasitic torque ripples in a PM synchronous motor

Permanent magnet (PM) synchronous machines with a sinusoidal back electromotive force are ideally capable of torque-ripple-free operation. However, parasitic torque ripples can still be induced from motor design and controller implementation. This paper focuses on a systematic analysis of possible sources of torque ripple in a PM synchronous machine drive resulting from limitations in the motor controller. It takes into account the effects of finite encoder resolution, controller CPU word length, current sensing errors, and inverter pulsewidth-modulation switching. Approaches for analyzing and calculating torque ripple from each of those sources have been developed. Characteristics of the various parasitic torque ripples are discussed. Experimental and simulation data to verify important results are also presented.     

永磁型无轴承电机的无传感器运行研究

在分析高频信号激励下永磁同步电机数学模型的基础上，针对永磁型无轴承电机无传感器运行的需要，提出了一种基于电机空间凸极跟踪的转子位置估算自检测方法，讨论了利用高频信号注入、外差法空间凸极信号提取及转子位置跟踪观测器设计等位置检测原理和实现技术，并应用这种位置检测方法建立了永磁型无轴承电机无位置传感器的矢量控制系统。仿真研究表明，上述空间凸极跟踪方法能在内插式永磁型无轴承电机全速范围内准确地观测出转子的位置，能在高、低速和大负载扰动下实现无传感器方式的稳定悬浮运行。     

EFFECT OF PARAMETER CHANGES ON THE PERFORMANCE OF SOLID ROTOR THREE-PHASE RELUCTANCE MOTORS

ABSTRACT

An adequate understanding of the close relation existing between performance characteristics and machine parameters is essential for designing any reluctance motor.

The present paper deals mainly with how the steady-state stability of small solid rotor three-phase reluctance motors is affected by the machine parameters. The effects of certain typical machine parameters have been quantitatively demonstrated, which may be instrumental in designing the motor.

To confirm the results obtained, a comparative review of calculated and experimental values is also presented for a number of different machines.     

双凸极永磁电机故障分析与容错控制策略

电机驱动系统的可靠性问题在实际应用中得到了相关领域学者越来越广泛地关注.在对容错电机的基本结构特点进行分析的基础上,针对现有容错电机的不足,对双凸极永磁(DSPM)电机的容错性能进行了研究.DSPM电机克服了开关磁阻电机和转子永磁型容错电机的各自不足,具有可靠性高和功率密度高等优点.为提高DSPM电机缺相运行特性,提出了一种容错控制策略,建立了DSPM电机驱动系统的联合仿真模型,并将其应用于容错性能分析.仿真和实验结果表明,DSPM电机是一种新型容错电机,具有较强的带故障运行能力.本文为新型定子永磁型容错电机的研究打下了基础.     

基于转子凸极跟踪的永磁同步电机转子位置的自检测方法

提出了一种永磁同步电机转子位置估算的自检测方法。文中讨论了利用旋转矢量载波高频信号注入、外差法及跟踪观测器检测转子位置的原理。同时给出了针对内埋式永磁同步电机的实验系统及实验结果。     

分层阻抗理论在永磁电机转子参数分析中应用

分层阻抗理论是研究实心转子感应电机的一种有效方法,表面磁钢永磁同步电机转子结构与复合转子电机具有相似性,文中采用分层阻抗理论对表面磁钢永磁同步电机转子参数分析并讨论     

Inverter-driven synchronous motors for constant power

Inverter-driven synchronous motors are widely used in high-performance variable-speed drive systems. In this article, the effects of machine parameters and the operating characteristics with respect to several types of synchronous motors-which include synchronous reluctance motors, surface permanent magnet synchronous motors, and interior permanent magnet synchronous motors-are examined. The optimum current vector producing the maximum output power at any speed is derived considering both current and voltage constraints     

Reluctance motor with strong rotor anisotropy

A new rotor design for the synchronous reluctance motor is presented. It has something in common with the segmented and axially laminated rotors that have been developed in the past. The new rotor achieves strong anisotropy by interleaving magnetic iron lamination with nonmagnetic spacers of approximately equal thickness. It is shown that the magnetizing inductance is very much lower in the quadrature than the direct axis and that this rotor has the potential to develop more torque than earlier machines. Laboratory results are presented, and the machine is compared with an induction motor in the same frame     

基于Maxwell 12的稀土永磁同步电机设计优化

针对传统的场路耦合法设计,永磁同步电动机磁路计算不准确的问题,采用永磁电机设计软件Maxwell 12完成对永磁同步电动机的设计优化。首先用该软件中的磁路法设计软件Rmxprt进行设计,对其中永磁体磁化方向长度和气隙对电机性能的影响作进行分析;然后再用其中的有限元分析软件Maxwell2D对永磁同步电动机的电磁场进行仿真,对设计进行合理性分析,最后结合两者的结果完成电机的优化设计。