Technical evolution of permanent magnet synchronous motors for home appliances

This paper reports on the highly efficient motor technologies used in home appliances in Japan. The permanent magnet synchronous motor (PMSM) is especially suitable because the use of permanent magnets does not require any extra current to produce magnetic power in the rotor, or any other kind of energy. In Japan, there has been a rapid shift from induction motors to PMSMs, and in this paper we will show several examples of PMSMs as applied to the home appliance field. It can be seen that great improvements have been made in high‐efficiency motor technologies. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A hybrid current controller for dual three‐phase permanent magnet synchronous motors

Control of the current harmonics is a critical issue for dual three‐phase (DTP) permanent magnet synchronous motors (PMSMs). Considering the limitations of conventional synchronous frame proportional‐integral (PI) current regulator, this paper presents a hybrid current controller that combines the PI current regulator with a multiresonant controller. With the proposed hybrid current controller, precise current control can be achieved with only a slight increase in the computational effort. Theoretical analysis and experimental results confirm the effectiveness of proposed current controller. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Multiobjective optimum design method with anti‐demagnetization of high‐density permanent magnet synchronous motor

This paper presents a method of multiobjective optimization design with anti‐demagnetization aiming at the problem of irreversible demagnetization in high‐density permanent magnet synchronous motors (PMSMs) due to temperature and external magnetic field, at the same time considering the volume of permanent magnets and cost, torque ripple, and core loss. In the first step, a two‐dimensional magnetic network model is used to rapidly assess the basic design parameters and its ability to avenge the anti‐demagnetization of the PMSM. In the second step, the finite element method (FEM) is used to design the key parts of motor, and regression models that solve the model of the multiobjective problem are built based on the simulation experiment data. On this basis, multiobjective optimization result using genetic algorithm is used that can achieve a fast and efficiently global optimal solution. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Trends of permanent‐magnet synchronous machine drives

This paper presents recent trends of permanent‐magnet synchronous motor (PMSM) drive technologies in Japan. Since the PMSM drives have many advantages over other drives, e.g. high efficiency, high power density, etc., many of the motor applications have been changing their power sources to the PMSMs. Particularly, interior permanent‐magnet synchronous motors (IPMSM) are epoch‐making and are intensively studied among researchers, scientists and engineers. According to the survey of the recent innovative technical trends, the PMSM drive technologies have been making a remarkable advancement in the fields of analysis‐and‐design techniques, various sensorless‐control techniques, power converter control techniques, and application specific drive systems. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Refinement of inverter model considering dead‐time for performance improvement in predictive instantaneous current control

Model predictive instantaneous‐current control (MPIC), which was proposed in our earlier works, enables us to achieve better instantaneous current control using mathematical models of an inverter and permanent magnet synchronous motors (PMSMs). However, dead‐time to avoid short breakdown in the inverter is not usually considered in a general inverter model. Such an unmodeled part in the inverter model prevents accurate prediction of current evolution in motor systems based on the model predictive control. Therefore, in this paper, we analyze current response resulting from the dead‐time in the MPIC, and propose a refined inverter model considering the dead‐time so that control performance is improved. The effectiveness of the proposed method is verified through simulation and experiments. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

New Dynamic Self‐Consistent Mathematical Model and Torque Characteristics of Permanent‐Magnet Synchronous Motors with Magnetic Cross‐Coupling

This paper proposes a new dynamic mathematical model of permanent‐magnet synchronous motors (PMSMs) with magnetic cross‐coupling and presents a new analysis of the torque characteristics of the motors. Generally speaking, dynamic mathematical models used for the design and analysis of PMSM control systems must consist of three basic equations that describe the main motor characteristics as an electrical circuit, torque generator, and electromechanical energy converter. In order to obtain reasonably compact models, some characteristics have to be approximated. However, in the case where the approximations used in the three basic equations are different from each other, the dynamic mathematical model often loses self‐consistency and becomes self‐contradictory. The proposed model, which takes the magnetic cross‐coupling into account, is self‐consistent and compact, and its effectiveness is validated by experimental data. Using the self‐consistency and compactness, this study presents a new analysis of the torque characteristics of PMSMs, focusing on efficient torque generation. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(1): 42–55, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22382     

New Simple High‐Quality Torque Control for Permanent‐Magnet Synchronous Motors: Compensating for Torque Ripple Caused by Nonsinusoidal Back EMF

This paper proposes a new and simple torque‐sensorless torque control method for permanent‐magnet synchronous motors (PMSMs) with nonsinusoidal back EMF. The method suppresses the sixth and/or 12th harmonic torque ripples caused by the back EMF in a feedforward manner even at high speeds; it consists of two subordinate methods for compensation command generation and command‐tracking current control. The first subordinate method generates compensation current commands to cancel the torque ripples based on a mathematical model of PMSMs. The second method controls the stator current to track a current command containing both fundamental and compensatory components. In conjunction with the current control, a dedicated disturbance observer that employs a digital speed‐varying band‐pass filter as a disturbance filter is also proposed. The effectiveness and usefulness of the proposed method were verified through extensive experiments.     

Trend of permanent magnet synchronous machines

The performance of permanent magnet synchronous machines (PMSMs) has improved rapidly by the progress in elemental technologies such as electromagnetic material technology, computer‐aided design technology, control technique, and drive circuit technology, and thus PMSMs are attractive as high‐performance machines in various fields. This paper describes the recent technology and the trends in PMSMs. To begin with the PMSMs are classified by the ratio of magnet torque to the reluctance torque and their features described, then the trend of the motor design and the electromagnetic material for highly efficient PMSM is shown. The technologies that help to reduce the vibration and noise are also described, and the recently developed PMSMs for traction drive application are introduced. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

永磁同步电机的发展趋势

随着电磁材料的发展、计算机辅助设计技术的进步、以及控制技术和驱动电路技术的进步,永磁同步电机（PMSM）的性能有了很大的提高。因此,永磁同步电机作为一种高性能电机在各种领域都具有广泛的应用空间。介绍了PMSM的发展趋势,首先描述了根据永磁转矩和磁阻转矩的比例,永磁同步电机的分类;其次介绍提高永磁同步电机效率的两个措施;最后分析了减少振动和噪声的技术,以及PMSM在牵引驱动方面的应用。     

Potentiality of a new minimum‐order back‐EMF state observer taking acceleration into account for sensorless vector control of permanent‐magnet synchronous motors

This paper proposes new sensorless vector control methods for permanent‐magnet synchronous motors (PMSMs), which are based on a new minimum‐order back‐EMF state observer taking acceleration into account, and examines potentiality of the improved back‐EMF observer through experiments. Conventional sensorless vector control methods for PMSMs using an estimate of back‐EMF are established under the assumption of constant speed or zero acceleration, and consequently cannot operate properly at modes requiring rapid speed change especially in low speed region. On the other hand, the proposed back‐EMF observer has the following features: (1) it is a new back‐EMF state observer taking acceleration into account and requiring no additional approximation to motor mathematical model; (2) it is a minimum‐order state observer; (3) it utilizes motor parameters in the simplest manner; (4) it can be applied to both salient‐pole and non‐salient‐pole PMSMs; (5) it can be realized in both rotor and stator reference frames. Detailed designs and analyses for the improved state observer and the sensorless vector control systems in both rotor and stator reference frames are given. In relation to the sensorless vector control systems, this paper newly proposes a double‐integral‐type PLL method and an integral‐feedback‐type acceleration/speed estimation method. Their potentialities are examined through experiments. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(4): 78–92, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/ eej.20630     

少稀土组合磁极Halbach永磁同步电机性能和材料成本研究

稀土永磁同步电机性能优越,但稀土永磁材料价格昂贵导致电机成本增加。因此,提出了一种新型少稀土永磁同步电机,其永磁体采用组合磁极Halbach结构。分析了少稀土组合磁极永磁同步电机的结构特点,并在此基础上,提出了少稀土T型、HAT型和LREH型三种组合磁极Halbach永磁同步电机拓扑结构。从电机空载反电动势、空载齿槽转矩和额定负载电磁转矩等方面分析了三种拓扑结构少稀土永磁同步电机,并与稀土永磁同步电机进行对比分析。在等转矩条件下研究了钕铁硼和铁氧体两种永磁体厚度对少稀土组合磁极永磁同步电机材料成本的影响。对比分析了稀土永磁同步电机和三种少稀土永磁同步电机的材料成本。有限元仿真结果表明LREH型少稀土组合磁极Halbach永磁同步电机具有更好的转矩性能和更低的材料成本。     

多相永磁同步电机缺相故障下的磁链动态特性分析

永磁同步电机(PMSM)电磁动态特性分析对电力传动系统运行与故障诊断策略研究具有重要作用。针对多相PMSM磁链的动态特性进行分析,推导了电感与转子位置关系,基于五相PMSM定子磁链的动态数学模型,采用MATLAB软件对五相PMSM在不同缺相故障下的磁链、电感特性进行建模和仿真,并对仿真结果进行了比较分析。研究结果可以为PMSM缺相故障诊断和容错控制提供一定的理论参考。     

New Simple Torque‐Sensorless Torque Control for Quasi‐perfect Compensation of Sixth‐Harmonic Torque Ripple Due to Nonsinusoidal Distribution of Back EMF of PMSM

This paper proposes a new torque‐sensorless torque control method for permanent‐magnet synchronous motors (PMSMs). The proposed method can almost perfectly compensate the sixth harmonic torque ripple that is caused by nonsinusoidal distributions of the back electromagnetic force and the rotor magnetic flux of PMSMs. The torque control system is, in principle, constructed on the basis of vector control, but has two new, dedicated speed‐varying devices: a harmonic torque observer and a current controller. The speed‐varying harmonic torque observer can estimate the harmonic component over a wide range of speeds, even when the generated torque is constant, and produce a suitable compensation signal. The speed‐varying current controller shows stable control performance over a wide range of speeds; it can fully track the compensated current command containing the DC and sixth harmonic components. The effectiveness of the proposed method is examined and verified through extensive numerical experiments.     

A New Self‐Tuning Power‐Factor‐Based Vector Control Method for Efficient Wide‐Speed Range Sensorless Drive of Permanent‐Magnet Synchronous Motors

As a simple sensorless vector control method for permanent‐magnet synchronous motor (PMSMs), a power‐factor‐based vector control (PFVC) method has been reported. This method has the attractive characteristics that three functions such as current limit, efficiency and sensorless drive can be performed simultaneously in a simple manner. However, it was developed under the assumption that there is no practical voltage limit, and that it cannot be applied over the rated speed. This paper proposes a new PFVC method that allows PMSMs to be driven even over the rated speed under application of a practical voltage limit, while keeping the desired characteristics. The effectiveness and usefulness of the proposed method are verified through extensive experiments.     

基于固定矢量作用时间的新型直接转矩控制系统

永磁同步电动机传统直接转矩控制具有转矩脉动大、开关频率不恒定等缺点,在分析传统直接转矩控制中磁链和转矩脉动的基础上,利用固定矢量作用时间合成新矢量的新型直接转矩控制方法控制永磁同步电动机.该方法根据转矩和磁链误差来选择基本电压矢量对,根据磁链的位置和转矩误差的大小来确定所选择的基本电压矢量的作用时间,从而得到了新的合成电压矢量进行控制.仿真结果表明基于固定矢量作用时间的新型直接转矩控制方法能够有效减小传统直接转矩控制方法中的磁链和转矩脉动,同时不增加控制的复杂性,明显改善了系统的控制性能.     

Extension of Mathematical Models Taking Temperature Variation in Permanent Magnet Synchronous Motors into Consideration

We have developed novel mathematical models of d‐axis and q‐axis magnetic fluxes ?_d and ?_q for permanent magnet synchronous motors (PMSMs). The models can be used to approximate magnetic characteristics using simple fractional equations with i_d and i_q as variables. They include eight constants, and some of them represent the degree of magnetic saturation and cross‐coupling. However, the magnetic characteristics are varied with the temperature rise in PMSMs, which are dependent on the load torque and motor speed. In this paper, the characteristics of the eight constants that vary with the motor temperature and the residual flux density B_r are shown. Further, we propose to extend the mathematical models by considering the temperature and B_r variation.     

Parameter measurements for permanent magnet synchronous machines

The advances in inverter drive technology and permanent magnet materials have enabled the application of permanent magnet synchronous machines (PMSMs) to various fields. PMSMs are rapidly spreading in their applications with their advantage of high efficiency, which is highly needed in many applications in recent years. Although there have been standardized measurement methods of the machine parameters for synchronous machines, they are not intended to apply to PMSMs. Therefore, several new measurement methods suitable for PMSMs have been proposed. This paper presents a review and analysis of these methods. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

单逆变器供电双五相永磁同步电机串联型直接转矩控制研究

电机串联技术不仅能够节省逆变器以及控制设备的成本,而且还能节省逆变器所占用的空间。串联的电机可实现独立控制,其转速和转矩都是独立控制的,这在诸多领域中有着重要的实用意义。针对2台串联的五相永磁同步电机PMSM（permanent magnet synchronous motor）提出一种直接转矩控制DTC（direct torque control）策略。首先,建立了变换矩阵,分析推导了静止坐标系以及旋转坐标系下双五相PMSMs串联系统的数学模型;然后,对直接转矩控制进行研究,构建最佳开关矢量表,设计系统的控制框图;最后,在MATLAB下建立电机的模型以及串联系统的模型,对单逆变器供电双五相PMSMs串联系统进行稳态及动态的仿真与分析。     

PMSM Sensorless Control Based on Position Estimation Correction Using All‐Pass Filters

This paper proposes a novel flux estimation method for the position sensorless control of permanent magnet synchronous motors (PMSMs). In general, the stator flux linkage for position estimation in PMSMs is obtained using the pure integration of voltages. The infinite dc gain of the pure‐integrator, however, causes numerical drifts in the obtained stator flux linkage due to the dc offset in the input of this integrator. To address this problem, a quasi‐integrator is often substituted instead of the pure integrator to restrict the dc gain, leading to another problem in which the phase characteristics vary according to the operating frequency. As a result, the ideal phase characteristics (?90° constant) cannot be held, and the position estimation performance deteriorates. Therefore, this paper proposes a phase characteristic correction method for quasi‐integrators using all‐pass filters, which achieves extremely precise estimation under transient conditions as well as in steady state.     

Permanent magnet synchronous motors using primarily reluctance torque

Permanent magnet synchronous motors (PMSMs) are widely used in many applications as high‐performance variable‐speed drives. In traction drives, such as those used for electric vehicles or for the compressor drives of air conditioners, a wide constant‐power speed range and high‐efficiency operation are desired. The aim of this paper is to develop a high‐performance PMSM that offers high‐efficiency performance in the high‐speed region, including light‐load conditions, as well as a wide constant‐power speed range. Simulations show that the proposed interior PMSM, which produces chiefly reluctance torque and in which the permanent magnet flux assists torque production, is capable of meeting the above performance requirements. A prototype PMSM is designed in accordance with this new design concept and several drive tests are carried out. The saliency ratio of the prototype IPMSM is about 5, and, as a result, reluctance torque is the principal torque component, representing more than 70% of total torque. The prototype IPMSM can attain a constant‐power speed range of up to 5:1 with high‐efficiency drive in the high‐speed, constant‐power region. The proposed IPMSM is suitable for variable‐speed drives requiring high‐speed, constant‐power operation. © 2000 Scripta Technica, Electr Eng Jpn, 134(3): 60–68, 2001