A super high speed PM motor drive system by a quasi-current sourceinverter

This paper describes a surface mounted PM motor with the ratings of 5 kW and 150000 RPM for super high speed drive applications such as a machine tool. A much larger air gap, compared with that of the existing PM motors, is utilized to reduce the slot ripples and hence the resultant eddy current loss in the metallic sleeve that retains the permanent magnets, otherwise this loss would be objectionable at such high speeds. The motor is supplied from a quasi-current source inverter with the DC current controlled by a chopper and operated at a near unity power factor by the use of a simple position sensor-less control, to improve the motor efficiency. The analytic results are presented to show the slot ripple reducing effect of increasing the air gap length. To investigate the losses of the sleeve, several motors with different sleeves were manufactured and tested. Typical experimental results on these prototypes are given, which show that motor efficiency of higher than 90% can be realized at the rated torque over a wide speed range     

Operating Limits of Inverter-Driven Permanent Magnet Motor Drives

Recent developments of high-energy permanent magnet (PM) materials such as neodymium-iron-boron have focused attention on the use of PM synchronous motors supplied from inverters for a wide variety of speed control applications. PM motor drives are readily applicable where full torque is required up to full or base speed. They are, however, limited in their ability to operate in the power-limited regime where the available torque is reduced as the speed is increased above its base value. In contrast with the field weakening approach used in dc drives, the magnet is permanent. The torque-speed operating limits of PM motor drives, of conventional design are explored, and then design measures which can substantially extend operation into the power-limited regime are proposed. A trade-off between the low speed-torque limit and the extent of the speed range above base speed is achieved by variations in magnet dimensions and the depth of inset of the magnets in the rotor iron. Experimental results are presented for two motors of different design, each using neodymium magnets and each supplied from a current-controlled inverter with hysteresis control of current waveshape.     

非理想反电动势无刷直流电机的转矩脉动抑制仿真研究

在伺服系统中要求电机转速平稳,抑制转矩脉动是实现转矩平稳的关键,而非理想反电势会引起较大转矩脉动。为了有效平滑无刷直流电机转矩,分析了两种不同的方法：根据定子电流和反电势与转矩表达式的关系,对于一台给定的电机,只要其反电势一定,通过优化定子电流就可以消除主要的转矩谐波分量,从而达到减小转矩波动的目的;通过坐标变换在厶=0时求解产生恒定电磁转矩所需的q轴电流,并在dq坐标系下通过矢量控制对q轴参考电流进行跟踪实现转矩脉动抑制。利用MATLAB／SIMULINK仿真平台建立系统的仿真模型,对系统模型进行仿真和分析并比较了这两种方法的特点,为实际电机的控制提供了研究方向。     

Permanent-Magnet Motors for Energy Savings in Industrial Applications

The present and future market for motors places a high value on operating efficiency, reliability, variable-speed operation, low running temperature, quiet operation, and low cost. Permanent-magnet (PM) motors are now able to meet these market expectations across an increasing range of ratings. Compared to the prolific induction motor, PM motors provide the attributes of efficiency, reliability, etc. They also have the additional advantages of higher power density, superior power factor (low current), low rotor temperature, and synchronous operation. Advancement in magnet technologies allows operation at higher temperatures without permanent magnetization loss. The economic viability of PM motors is increasing with additional sources offering rare-earth magnets such as neodymium iron boron at lower prices. Performance comparisons between induction motors, surface PMs, and salient-pole PM motors are presented in this paper.      

不同极槽配合电动汽车永磁同步电机弱磁性能及抗饱和能力研究

电动汽车永磁同步电动机需要宽的调速范围,但在高速弱磁时,铁心的饱和带来了较大的反电势失真和转矩波动,影响电机的运行性能。本文比较分析不同极槽配合的内置永磁同步电机高速弱磁工况的反电动势、电磁转矩和转矩波动情况。仿真分析表明,在高速弱磁条件下与分数槽电机相比,整数槽永磁同步电动机具有较高的反电势失真率和转矩波动;其中36槽8极电机弱磁能力最好,18槽8极电机转矩波动最小。     

Six-step Voltage Control of PM Brushless AC Motors under High Speed Flux-weakening Operation for EV/HEV Applications

The torque-speed characteristics of brushless motor having an interior permanent magnet rotor and a sinusoidal back-emf waveform are compared experimentally when it is operated in brushless AC(BLAC) mode and brushless DC (BLDC) modes with both 2-phase,120° conduction(BLDC-120) and 3-phase,180° conduction(BLDC-180).Particular emphasis is on high-speed,six-step voltage controlled,flux-weakening operation.It is shown that for EV/HEV applications,even for interior PM brushless motors which have sinusoidal back-emf waveforms,in order to achieve maximum torque per ampere capability over wide operation speed range,it is advantageous to employ a hybrid operation mode-BLAC operation in the constant torque region and six-step voltage control(BLDC-180 operation,together with current phase control) in the flux-weakening region.     

Modeling and Design Optimization Of Permanent Magnet Motors

ABSTRACT

Variable-speed permanent (PM) magnet motors are being used in an ever-increasing range of industrial and commercial applications. The objective of this paper is to provide a basis for optimizing the design of such permanent magnet motors and, through this, to provide insight into a comparison of PM motors with other types of drive motor. First, design models are presented for the approximate analysis of torque capability, losses, thermal characteristics, magnet protection and power factor control. These models are then used in an optimization program using sequential unconstrained minimization techniques to produce designs for a wide range of motor torque ratings. In order to examine the potential for large PM motor drives, the design criterion chosen for emphasis in optimization is the minimum total lifetime cost, including the cost of losses. The high efficiency and good power-to-weight ratio of the optimized PM motors leads to a total present value cost which is expected to be significantly lower than achieved with induction motors.     

非理想梯形波反电势的永磁无刷直流电机换相转矩脉动抑制方法

为了提高磁悬浮控制力矩陀螺(magnetically suspended control moment gyro, MSCMG)框架伺服的精度与稳定度,针对永磁无刷直流力矩电机(permanent magnet brushless DC motor, PMBLDCM)非理想梯形波造成的换相转矩脉动,分析指出了换相反电势不平衡是造成转矩脉动产生的又一原因,且是影响低速力矩电机换相转矩脉动的主要因素。在单一直流母线电流反馈的基础上,提出了一种换相转矩自平衡控制方法,其中包括换相转矩平衡点观测器和角加速度的快速最优估计算法,有效的抑制了换相转矩脉动,提高了低速时的速率伺服精度与稳定度。     

新型混合励磁同步电机分区控制系统分析与设计

混合励磁同步电机综合了永磁电机和电励磁电机的优点,具有显著的宽调速特征。该文根据混合励磁同步电机的结构特点,结合空间电压矢量控制,提出了混合励磁电机的一种宽调速控制新方法。该控制方法在分区控制的基础上,低速区结合电机铜耗最小原理,高速区保持反电势q轴分量恒定,对不同运行区域分别采用不同的控制策略,使电机在整个运行区间都能表现出良好的性能。由于在高速区采用了励磁电流和d轴电流弱磁相结合的方式,使用该类调速系统比现有文献单纯采用励磁电流弱磁调速具有更宽的调速范围。实验表明,所设计的混合励磁同步电机宽调速系统,在低速区增磁运行时,通过调节励磁可以将转矩输出能力提高约1/3;高速区弱磁运行时,可将最高转速提升约1.5倍。     

A novel permanent magnet motor with doubly salient structure

A new type of doubly salient machine is presented in which the field excitation is provided by nonrotating permanent magnets. This doubly salient permanent magnet (DSPM) motor is shown to be kindred to square waveform permanent magnet brushless DC motors. Linear and nonlinear analyses are made to investigate the characteristics of this new type of PM motor. A prototype DSPM motor is designed and comparisons made between this new type of motor and the induction motor. It is shown that by fully exploiting modern high energy PM material and the doubly salient structure, the DSPM motor can offer superior performance over existing motors in terms of efficiency, torque density, torque-to-current ratio, torque-to-inertia ratio etc., while retaining a simple structure amenable to automated manufacture     

Halbach永磁阵列无刷直流电机转矩的解析计算和分析

Halbach永磁阵列具有灵活配置电机气隙磁通密度、磁屏蔽的特点,将其用于无刷直流电机以增加电磁转矩、降低齿槽转矩。在保角变换求解电磁场基础上,给出无刷直流电机电磁转矩与齿槽转矩的解析计算模型,通过有限元仿真对该模型的准确性进行证明;使用该模型分析每极两块(1P2p)、每极三块(1P3p)Halbach永磁阵列中主磁钢弧角和辅磁钢充磁方向角对无刷直流电机电磁转矩与齿槽转矩的影响,对比分析径向充磁、平行充磁和Halbach永磁阵列的无刷直流电机电磁转矩与齿槽转矩随永磁体厚度的变化规律。分析结果表明,合理配置无刷直流电机Halbach永磁阵列中主磁钢弧角和辅磁钢充磁方向角可提高电磁转矩、降低齿槽转矩,当永磁体厚度增加时,Halbach永磁阵列更有利于电磁转矩增加。     

High torque induction motor with rotating magnets in the rotor

This paper describes a new type high torque induction motor which has the rotating magnets in the rotor. The motor basically consists of a usual stator, cylindrical rotor, and inner cylinder of which the surface is covered by a set of magnets. The rotor turns at somewhat less than synchronous speed. The inner cylinder with magnets can revolve freely against a rotor shaft. The magnets revolve synchronized by the rotating magnetic field induced by the stator current. The magnets make the flux in the rotor. Then we can expect torque increase by the increase of the flux. The results of magnetic field analysis indicate the flux is increased. In the experimental results of a test motor which is a 400 W prototype machine, we have obtained the torque increase by approximately 20 percent as anticipated in the magnetic field analysis. Moreover, test results show improvements of efficiency and power factor in the motor operations. The efficiency of the test motor is obtained as high as 10 percent at the rated output over those of a same size conventional induction motor. Although power factor of conventional induction motors is lagging at all times, the test motor can be operated with near unity, leading or lagging by adjusting the ac supplied source voltage.     

一种改善BLDCM调速性能的模糊矢量控制策略

针对永磁无刷直流电机(BLDCM)在方波控制时转矩脉动大、电流畸变程度大以及反电势不稳定造成转速波动的问题,本文在分析BLDCM控制方式的基础上,将这些问题的原因归结于控制时的电流换相以及反电势并非理想方波电势。基于此,针对电动汽车BLDCM提出一种基于模糊控制的无刷直流电机矢量控制调速策略,此策略使用模糊控制器对转速误差进行调节,进而增强系统的调速性能;使用矢量控制取代方波控制,进而克服转矩脉动、电流畸变以及反电势不稳定等问题。实验结果表明,本文提出的控制策略能较好地抑制转矩脉动,并使电流以及转速更加平滑稳定。     

永磁同步电机低转矩脉动的稳健设计

在电机生产加工过程中引起的尺寸和形位公差、安装误差、材料属性偏差等噪声因子,造成了批量生产的电机间的转矩脉动特性分散,进而影响高精度永磁同步电机系统控制性能的一致性。为保证高精度场合用永磁同步电机的转矩脉动特性具有良好的稳健性,采用田口稳健设计方法,选取的噪声因子包括磁钢的周向安装位置、充磁角度、剩磁大小的误差、气隙加工误差、转子静态和动态偏心以及传感器安装误差等,通过优化磁钢、齿槽、气隙等电磁设计参数的名义尺寸,达到降低转矩脉动系数的均值和分散区间的目的。对比分析了稳健设计、正弦反电势设计和均匀气隙设计3种方案,结果表明,在相同噪声因子的影响下,与另两种设计方案相比,采用稳健设计方案,转矩脉动系数的均值和均方差显著降低。以转矩脉动系数作为优化目标,有效地满足了转矩脉动和平均转矩的多目标优化要求。     

一种抑制非理想反电势的BLDC电机转矩脉动的方法

转矩特性是电机性能的重要指标,而抑制转矩脉动是无刷直流机(BLDC motors)控制领域中的关键技术之一.本文针对非理想反电势的无刷直流机,对转矩脉动谐波构成进行了推导,分析了转矩脉动和反电动势谐波、电流谐波的关系,提出了一种基于离线反电势测量的优化电流算法,结合空间电压PWM,实现了抑制转矩脉动的电流闭环控制.仿真和实验证明,该方法可以显著抑制转矩六次谐波,是一种有效的改善无刷直流机转矩性能的方案.     

新型永磁开关磁链电机

分析设计两种具有结构简单、转矩密度高等优点的新型三相永磁开关磁链电机，并利用二维有限元软件分析电机几何形状对反电动势波形、齿槽定位转矩和径向不平衡力等因素的影响，并以此为基础进行优化设计。     

永磁无刷直流电机负载磁场及其电磁转矩的计算

该文在考虑齿槽影响的前提下，建立了永磁无刷电机电枢反应磁场的解析计算模型，求出永磁电机相绕组的自感和互感。在对水磁无刷直流电机空载气隙磁场和空载相绕组反电动势求解的基础上，结合永磁无刷直流电机主电路的拓扑结构，构造出电机绕组的场路耦合模型，由此计算出电机相绕组电流变化波形。在考虑齿槽影响情况下，计算出永磁电机在任意时刻的电枢反应磁场和负载气隙磁场，进而计算出永磁无刷直流电机产生的瞬时电磁转矩，以便定量分析永磁无刷电机的电磁转短被动和绕组换相引起的转矩被动，为分析永磁无刷直流电机的工作特性和振动噪声提供了可靠的依据。     

变频调速异步电机的优化设计

随着变频调速技术的发展，异步电机在工业传动领域中的应用越来越广泛。传统的异步电机设计方法已经不适应变频调速异步电机的设计要求。传统电机的设计重点在于额定点效率、功率因数、最大转矩、起动转矩、起动电流、运行温升和价格等指标。而变频调速电机的设计重点是在调速范围内的效率、功率因数、温升，以及动态响应性能等。本文根据变频调速集成系统的特点，提出具有针对性的变频调速电机优化设计策略。该策略具有以下几个特点：①采用自适应设计模型；②针对变频器供电的谐波影响分析模型；③采用最优滑差控制和面向系统的优化设计方法。利用该优化设计方法，使得变频调速异步电机更加高效节能。     

无刷直流电机的直接转矩控制研究

直接转矩控制在正弦波交流电机方面的研究已趋于成熟,在反电势梯形波的电机研究方面相对较少.通过分析无刷直流电机直接转矩控制的基本原理,合理地选择空间电压矢量,将直接转矩控制技术应用于无刷直流电机的控制.运用Matlab/Simulink对其进行仿真,结果表明,永磁无刷直流电机转速响应迅速,转矩脉动非常小,取得了良好的控制...     

Indirect sensing for rotor flux position of permanent magnet ACmotors operating over a wide speed range

This paper describes an indirect sensing, or sensorless, method for rotor flux position for brushless permanent magnet (BPM) motors operating over a wide speed range, while keeping maximum torque per ampere and/or maximum efficiency capabilities. The method described is particularly applicable to trapezoidal back emf type of BPM motors. The typical trapezoidal waveform of the motor internal voltages (or back emf) contains a fundamental and higher order frequency harmonics. In particular, the third harmonic component is extracted from the stator phase voltages while the fundamental and other polyphase components are eliminated via a simple summation of the three phase voltages. The resulting third harmonic signal keeps a constant phase relationship with the rotor flux for any motor speed and load condition, and is practically free of noise that can be introduced by the inverter switching, making this a robust sensing method. In contrast with indirect sensing methods based on detection of the back-emf signal that require heavy filtering, the third harmonic signal needs only a small amount of filtering to eliminate the switching frequency and its side bands. As a result, the method described here is not sensitive to filtering delays, allowing the motor to achieve a good performance over a wide speed range. Motor starting is also superior with this method since the third harmonic signal can be detected and processed at lower speeds than for the conventional method of back-emf sensing