Effect of Axial Segmentation of Permanent Magnets on Rotor Loss in Modular Permanent-Magnet Brushless Machines

This paper presents a computationally efficient technique in determining the influence of the finite axial length of the permanent magnets on the rotor eddy-current loss in modular brushless ac machines. The technique is employed to quantify the effectiveness of axially segmenting the permanent magnets of four-phase, eight-slot, ten-pole and five-phase, ten-slot, 12-pole brushless machines, which have been designed to meet the performance requirements of an electromechanical flight control surface actuator for a "more-electric" aircraft.     

PWM调制方式对永磁无刷直流电动机换相转矩影响的分析

介绍一种用于人工心脏的轴流式血泵永磁无刷直流电动机换相转矩脉动变化过程。根据影响电动机换相转矩脉动的因素,给出了一种减小电动机转矩脉动的解决方案,以使电动机运行更加平稳。通过实验波形证实本结论分析正确,可以为电动机减小转矩脉动作参考。     

Unbalanced Magnetic Forces in Permanent-Magnet Brushless Machines With Diametrically Asymmetric Phase Windings

A general analytical model, formulated in 2-D polar coordinates, is developed to predict the unbalanced magnetic force, which results in permanent-magnet brushless ac and dc machines having a diametrically asymmetric disposition of slots and phase windings. It is shown that the unbalanced magnetic force can be significant in machines having a fractional ratio of slot number to pole number, particularly when the electric loading is high. The developed model is validated by finite-element calculations on 9-slot/8-pole and 3-slot/2-pole machines. In addition, the unbalanced magnetic force has been measured on a prototype 3-slot/2-pole machine and shown to be in excellent agreement with predicted results.     

不同运行状态下永磁无刷直流电机铜损分析

为了准确分析永磁无刷直流电动机的运行特性,需要了解电机驱动恒转矩负载或恒功率负载时,不同的母线电压和占空比,对母线电流I1、绕组电流I-rms、铜损PCu1= 2I21以及PCu2=3I2-rmsR变化趋势的影响.从理论上分析了母线电流I1、绕组电流Irms-、铜损PCu1和pCu2的变化趋势以及pCu2-PCu1差值...     

永磁交流伺服电动机的参数分析

从永磁交流伺服电动机的基本结构出发,通过数学模型的建立和运用坐标变换,对方波和正弦波电流驱动两类永磁伺服电动机的参数及其相互关系进行了分析和阐述,并提出了新的实用的测试方法.     

开关频率对无刷直流电动机转矩脉动的影响分析

利用星形3相6状态无刷直流电机的数学模型和动态方程,讨论了PWM电压源逆变器驱动的永磁无刷直流电动机在导通运行区域和换向过程的转矩特性.通过数学解析得出,无刷直流电动机无论运行在导通区还是换向区,电磁转矩脉动都由直流供电电压、逆变器的开关频率及占空比、电机电气参数和转速高低共同决定,电磁转矩脉动与逆变器开关频率成反比关系.通过仿真和实验验证了PWM开关频率对转矩脉动的影响,为减小转矩脉动和驱动系统的设计提供了理论依据.     

永磁无刷电动机转矩特性

转矩脉动控制是衡量永磁无刷电动机性能好坏的一项重要指标,抑制转矩脉动成为提高永磁无刷电动机伺服系统性能的关键,研究永磁无刷电动机转矩特性抑制或消除转矩脉动具有十分重要的意义。     

PWM变频器供电交流励磁发电机输出谐波分析

研究由交－直－交固定载波型ＰＷＭ变频器供电励磁的发电系统的谐波特性,给出ＳＰＷＭ、ＳＶＰＷＭ调制模式下变频器输出谐波的解析表达;根据交流励磁电机谐波电路模型,导出定子侧“电源谐波”的解析表达;通过计算实例分析和比较ＳＰＷＭ与ＳＶＰＷＭ两种模式下的谐波特性,为励磁变频器类型选择和谐波抑制策略提供依据。     

DSP永磁无刷直流电动机的起动方法

TMS320LF2407AIR2132SIGBT逆变桥M～电流电压检测电路图2 反电动势无刷直流电动机伺服控制系统框图无刷直流电动机目前常用的无位置传感器控制多为反电动势控制,由于无刷直流电动机在静止的时候没有感应电动势,因此这种控制方式无法实现自起动,它的起动需要单独设计,本文采用T     

The Use of Permanent-Magnet Machines in Ship Electrical Systems

Ships are autonomous objects in which the capacity of the power plant and volume of available space are limited. Permanent-magnet machines with the maximum coefficient of efficiency and minimum mass and dimensions can be widely used on the ships, first of all, in high-power ship systems—generator sets, propulsion systems, and thrusters. However, there is a danger of fire during interturn faults in the stator winding in permanent-magnet machines. If such a fault occurs in the standard operating mode, then, when the rotor turns by inertia or, under the action of slowing water flow, moves to the propeller in the closed circuit of the stator winding, an electromotive force will be induced since the magnetic field of the rotor remains. This electromotive force will produce a current in the closed circuit, and a large amount of heat will be released in the winding-fault area, which can lead to a fire on the ship. This article considers a method of “damping” of the magnetic field in the rotor in an emergency situation. In this method, the magnetic system of the rotor is made of two parts, one of which is fixed on the rotor, while the second is installed on the rotary sleeve. In the normal condition of the machines, the angular positions of the analogous poles fixed on the rotor and installed on the rotary sleeve coincide. In the emergency condition of the machine, the sleeve turns so that the angular positions of the opposite poles of the rotor and sleeve coincide. As a result, the induction of the magnetic field in the gap and the electromotive force in the stator windings in the emergency condition of the machine will be close to zero.     

Position Estimation of AC Machines Over a Wide Frequency Range Based on Space Vector PWM Excitation

This paper presents a new method for position estimation in shaft-sensorless ac motor drives over the entire speed range, including zero frequency. The method is based on the standard fundamental wave space vector pulsewidth-modulation (PWM) excitation sequence and requires neither an observer-based model nor a signal injection test signal. Experimental results confirm the effectiveness of the new technique, and a comparison with other PWM-excitation-based methods for estimating the rotor position of ac machines is made.     

电机参数误差对永磁同步电机弱磁性能的影响

在矢量控制的永磁同步电机控制系统中,d轴和q轴电流的控制一般是根据电机数学模型推导的最佳性能轨迹,如恒力矩区的每安培电流最大力矩控制和弱磁区的最大功率控制。文中通过大量的实验,研究了当电机模型使用了不精确的各种电机参数后,对永磁同步电机的性能产生的不同影响。     

EPS永磁无刷直流电动机齿槽脉动转矩抑制方法

分析了一种有效降低永磁无刷直流电动机脉动转矩的全新转子结构,并试制了一台12V电动助力转向(EPS)永磁无刷直流电动机,通过对比实验验证了这种方法可以有效降低由齿槽效应引起的无刷直流电动机转矩脉动.     

集中绕组永磁无刷直流电动机反电动势分析

针对集中绕组永磁无刷直流电动机,提出了反电动势的分析方法,推导出了计算公式,得出了计算波形,与电动机反电动势实测波形进行了比较,并讨论了每极每相槽数对反电动势的影响。     

无刷双馈电机控制策略发展综述

在分析无刷双馈电机结构与工作原理的基础上,详细介绍了无刷双馈电机标量控制、直接转矩控制、矢量控制、模糊控制的发展现状,以及不同控制策略的适用场合,并对无刷双馈电机控制策略的发展进行了展望.     

集中绕组永磁无刷直流电动机反电动势分析

针对集中绕组永磁无刷直流电动机,提出了反电动势的分析方法,推导出了计算公式,得出了计算波形,与电动机反电动势实测波形进行了比较,并讨论了每极每相槽数对反电动势的影响。     

稀土永磁无刷直流电动机的应用与市场前景

永磁无刷直流电动机用电子换向替代了电刷和换向器,可以实现高性能、高可靠性、长寿命、免维护的目的。永磁无刷直流电动机是集交流电动机和直流电动机优点于一体的机电一体化产品。     

两种典型的场调制型永磁电机的对比分析

该文对比分析了两种典型的场调制型永磁电机,即常规永磁游标电机和双永磁励磁电机的性能和特点.首先介绍两种电机的结构,总结它们的结构特点;接着通过推导两种电机的一般性表达式,即空载反电动势及输出转矩,揭示两种电机的工作原理,比较"单向磁场调制效应"与"双向磁场调制效应";最后利用有限元法对比分析两台电机的性能,验证一般性表...     

内置式无刷直流电动机齿槽转矩的分析与抑制

齿槽转矩是由永磁体与磁槽之间相互作用而产生的,它会引起转矩脉动.利用虚位移法计算和分析齿槽转矩的影响因素,采用优化极弧、定子开辅助槽和调整定子齿槽宽度三种方法做了定性和定量的分析,并通过对24槽4极内置式无刷直流电动机进行有限元仿真,得出此类电机减小齿槽转矩的有效方法,并分析了对反电动势的影响,为内置式无刷直流电动机设计提供理论参考.     

Analysis of Rotor Core Eddy-Current Losses in Interior Permanent-Magnet Synchronous Machines

This paper presents the results of an investigation focused on the rotor core eddy-current losses of interior permanent-magnet (IPM) synchronous machines. First, analytical insight into the rotor core eddy-current losses of IPM machines is developed. Next, major design parameters that have the most significant impact on the rotor core eddy-current losses of IPM machines are identified. Finite-element analysis results are then presented to compare the predicted eddy-current losses in the machine core of IPM machines with one- and two-layer rotors coupled with concentrated- and distributed-winding stators. It is shown that the lowest total eddy-current losses in the machine core are achieved using a combination of distributed stator windings and two magnet layers per rotor pole, whereas minimizing only the rotor core eddy-current losses favors replacement of the rotor with a single-layer configuration.