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.     

Performance evaluation and experimental analysis of a novel single‐phase brushless PM motor

In order to equip the single‐phase brushless permanent magnet (PM) motor with self‐starting capability without a complex structure, we present a new kind of asymmetric air‐gap topology which can lead to the d‐ , q ‐axis magnetic circuit asymmetry of the motor. The field‐circuit‐coupling finite element method simulation model of the proposed motor controlled with a constant V / f control is built by using the 2D Maxwell software. The geometric parameters of the motor are also optimized by changing pole arc ratio of the PM (α_p ) and its eccentricity (e ), and the operational characteristic is investigated. Finally, an experimental platform of the prototype and its control system are set up. Performance comparison of the experimental results and simulation results of the proposed motor running in various operating modes is reported. All the results show that the asymmetric air‐gap single‐phase brushless PM motor has potential to be used in the household appliances. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Optimum design of a multilayer interior permanent magnet synchronous motor using reluctance torque

The report analyzes the results of experiments done with an inverter drive interior permanent‐magnet (IPM) motor. We examine results of both FEM (finite element method) simulation and experiments using a prototype motor with identical conditions set for stator and magnet volume. The results indicated that with magnets implanted inside the rotor, the values for the d‐axis inductance of the motor remained roughly the same, unaffected by the shape or number of layers. However, the q‐axis inductance exhibited significant change. This research report compares an IPM motor having two layers of permanent magnets with a motor having a single layer. The dual layer shows a 30% or greater increase in torque using the same current. These results indicate that this motor is especially effective for such applications as robots, plant machinery, compressor motors, and electric vehicles. © 1999 Scripta Technica, Electr Eng Jpn, 127(1): 64–72, 1999     

轨道车辆用永磁同步电机系统弱磁控制策略

内置式永磁同步电机可利用其磁阻效应来提高电机效率和改善调速特性,适宜用作轨道车辆的牵引电机。研究了轨道车辆用内置式永磁同步电机的弱磁控制,提出了利用电压极限椭圆的梯度下降法进行弱磁和电流参考值修正的新方法。该方法主要分为弱磁区域的确定和电流参考值的修正。弱磁区域由恒转矩曲线方向和电压极限椭圆递减方向之间的夹角大小来确定,电压极限椭圆递减方向信息通过梯度下降法计算得到。电流参考值的大小根据不同弱磁区域内弱磁方向和电压差值的幅度大小来确定。采用Matlab软件建立了系统仿真模型,针对100kW的轨道车辆用永磁同步电动机开发了基于TMS320LF2407A DSP的弱磁控制系统实验平台。仿真和实验结果证明了该策略的有效性。     

A single‐stage high power‐factor bridgeless AC‐LED driver for lighting applications

An alternating‐current light‐emitting diode (AC‐LED) driver is implemented between the grid and lamp to eliminate the disadvantages of a directly grid‐tied AC‐LED lamp. In order to highlight the benefits of AC‐LED technology, a single‐stage converter with few components is adopted. A high power‐factor single‐stage bridgeless AC/AC converter is proposed with higher efficiency, greater power factor, less harmonics to pass IEC 61000‐3‐2 class C, and better regulation of output current. The brightness and flicker frequency issues caused by a low‐frequency sinusoidal input are surpassed by the implementation of a high‐frequency square‐wave output current. In addition, the characteristics of the proposed circuit are discussed and analyzed in order to design the AC‐LED driver. Finally, some simulation and experimental results are shown to verify this proposed scheme. Copyright © 2012 John Wiley & Sons, Ltd.     

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.     

A new modeling approach for circuit‐field‐coupled time‐stepping electromagnetic analysis of saturated interior permanent magnet synchronous motors

This paper proposes a new modeling approach for circuit‐field‐coupled time‐stepping electromagnetic analysis of a saturated interior permanent magnet synchronous motor (IPMSM). To predict the drive performance quickly, the proposed approach consists of a dynamic simulator based on a new analytical model of the d‐ and q‐axis magnetization characteristics (λ‐i_d‐i_q‐θ). The model can take into account not only cross‐saturation but also the harmonics of the inductance distributions and EMF waveforms. The validity of the model is verified from suitable simulation results for the instantaneous current and torque waveforms of the IPMSM. The proposed analysis leads to a dramatic reduction in the computation time compared to circuit‐field‐coupled time‐stepping FEA, while maintaining analytical accuracy. The effectiveness of the proposed method is experimentally verified using a 10‐kW, 15,000‐rpm concentrated‐winding IPM motor. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(1): 49–58, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21024     

High‐power‐factor single‐switch AC to DC converter for LED lighting

In this paper, we report a novel single‐switch AC to DC step‐down converter suitable for light emitting diodes. The proposed topology has a buck and a buck–boost converter. The circuit is designed to operate in the discontinuous conduction mode in order to improve the power factor. In this topology, a part of the input power is connected to the load directly. This feature of the proposed topology increases the efficiency of power conversion, improves the input power factor, produces less voltage stress on intermediate stages, and reduces the output voltage in the absence of a step‐down transformer. The theoretical analysis, design procedure, and performance of the proposed converter are verified by simulation and experiment. A 36 V, 60 W prototype has been built to demonstrate the merits of this circuit. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Development of a new sensorless vector‐controlled and transmissionless electric vehicle using a permanent‐magnet synchronous motor

One of the most important technologies for electric vehicles (EVs) will be drive control technology for the main motor. It is desired that the drive control technology have the following characteristics. (1) It does not require a position/speed sensor for controlling motor drive, which has been mounted on the rotor shaft. (2) It has vector controls that can produce torque quickly, efficiently, and/or precisely. (3) It has wide driving‐range and allows developing EVs with no variable transmission. This paper proposes new drive control technologies for such EVs using a permanent‐magnet synchronous motor as a main motor, and verifies its usefulness through development of an actual EV that can drive on public roads. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(3): 83–94, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20459     

变速永磁同步发电系统功率分析

针对内燃机车永磁同步发电系统电机运行效率和功率因数较低的问题,应用最大转矩电流比(MTPA)控制策略来控制牵引变流器,并分析电压极限椭圆限制下的MTPA控制,与单位功率因数控制和id=0控制策略下的功角、功率因数和效率进行对比。仿真对比分析表明:id=0控制调速范围较窄,单位功率因数控制高转速下运行不稳定,MTPA控制可以在全速范围内稳定运行,并且提高了永磁同步发电机的功率因数和效率,增加了系统的稳定性。     

Identification of the parameters of the high‐frequency equivalent circuit of PM synchronous motor based on genetic algorithm

This paper presents an identification technique of parameters of a high‐frequency equivalent circuit of permanent magnet synchronous motors (PMSM) driven by a PWM inverter. The high‐frequency oscillatory currents such as leakage current to the motor frame (common‐mode current) and high‐frequency oscillatory line current (normal‐mode current) are generated by switching instants of inverter transistors. The parameters of the high‐frequency equivalent circuit of PMSM which can simulate the oscillating current are identified by means of genetic algorithm. It is shown that the high‐frequency equivalent circuit with identified parameters can generate the oscillating current by some simulation results. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(4): 57–66, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20717     

Principle and basic characteristics of linear synchronous motor with half‐wave rectified self excitation

This paper presents the principle and basic characteristics of a novel linear synchronous motor based on “half‐wave rectified self excitation principle.” The field winding is short circuited through a diode and the armature winding consists of conventional three‐phase windings. If the amplitude of the balance three‐phase currents is modulated by an alternating wave with bias frequency, the produced magnetomotive force pulsates at the bias frequency and moves at the synchronous velocity. This pulsating magnetomotive force induces the electromotive force with a bias frequency in the field winding. The field excitation is obtained by rectifying the electromotive force with the diode in the field winding. In this paper, the authors design and build an experimental machine and confirm its basic characteristics. They also deduce the performance equations and investigate the thrust ripple reduction. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(1): 82–90, 2008; Published online in Wiley InterScience ( www. interscience.wiley.com ). DOI 10.1002/eej.20684     

长线路轻负荷永磁同步电机功率因数的现状及改进途径

以油田电网为实例,通过对现场运行的永磁电机的大批量测试发现,在供电线路很长的情况下,其功率因数可能显著降低,从而导致其不节能或者节能效果不好.主要原因是电压偏差较大导致与永磁电机的感应电势不匹配;对于轻载运行的永磁电机,即使电压偏差值仍然在国家标准允许的范围,功率因数也可能降低至异步电机的水平.提出采用电源电压自匹配稀土永磁电机及相关控制系统,可有效提高永磁电机对电源电压偏差的适应性,并提供了相应的技术方案.实测表明,在电压偏差7％且电机的负载率在20％的条件下,可使永磁电机的功率因数从约0.75提高到0.95以上.     

A power decoupling control method for an isolated single‐phase AC‐to‐DC converter based on a high‐frequency cycloconverter

This paper proposes a new power decoupling method for a high‐frequency cycloconverter which converts the single‐phase line‐frequency ac input to the high‐frequency ac output directly. The cycloconverter consists of two half‐bridge inverters, two input filter capacitors, and a series‐resonant circuit. The proposed power decoupling method stores the input power ripple at double the line frequency in the filter capacitors. Therefore, the proposed method achieves a unity power factor in ac input and a constant current amplitude in the high‐frequency output without any additional switching device or energy storage element. This paper theoretically discusses the principle and operating performance of the proposed power decoupling method, and the viability is confirmed by using an experimental isolated ac‐to‐dc converter based on the high‐frequency cycloconverter. As a result, the proposed power decoupling method effectively improved the displacement power factor in the line current to more than 0.99 and reduced the output voltage ripple to 4% without any electrolytic capacitor.     

Compensation for neutral point potential in a three‐level inverter using motor currents of a permanent magnet synchronous motor and its characteristics

A three‐level inverter has several advantages of large capacity, large voltage, and low current waveform distortion. However, there is an important problem of neutral point potential variation in three‐level inverters. The variation causes an unbalance in the dc link voltage levels and current waveform distortion. In this paper, we propose a new method to control the neutral point potential. First, the neutral point potential variation in a three‐level inverter for permanent magnet synchronous motor drive is analyzed by state variable method and is calculated on the basis of the analytic results. Second, using the estimated value, proposed compensation for the variation can be done. Third, analytic and experimental results of the proposed method are compared with the results of feedforward compensation by simply adjusting the vector output intervals. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 139(4): 56–63, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10033     

Examination of new vector control system of permanent magnet synchronous motor for high‐speed drives

A new vector control system for permanent magnet synchronous motor drives has been developed. To stabilize the current control loop in the high‐rotating‐speed region, a novel configuration of current controller is introduced. The unique characteristic of the proposed current controller is that the current regulator is connected to the conventional motor model in a series. By analyzing the transfer characteristics of the control, it became clear that the influence of the coupling component between the d–q axes can be deleted theoretically if the control parameters are set properly. The stability and torque response of the proposed vector control system were improved, and the effectiveness of the proposed controller was demonstrated by a time domain simulation and some experiments. In addition, the robustness of the controlling system was investigated experimentally. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(4): 61–72, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21123     

Optimal current control methods of a non‐salient pole hybrid field‐synchronous motor for energy‐efficient and wide speed‐range operation

This paper proposes new practical optimal current control methods for a newly emerging class of non‐salient pole synchronous motors with hybrid rotor fields by both permanent magnet and winding. In practical situations with limited voltage, the extensively used permanent magnet synchronous motor hardly achieves an ideal performance that allows simultaneously both low‐speed high‐torque and wide speed‐range operations, due to its constant magnet field. Hybrid field synchronous motors (HFSM) have recently emerged to achieve ideal performance as practical motors with controllable hybrid rotor field. For HFSM, the same torque can be produced by a variety of currents due to nonlinearity between torque and currents. Consequently, appropriate determination of a set of stator and rotor current commands plays a key role in achieving possible energy‐efficient and wide speed‐range operation. Proposed methods determine the current commands corresponding to a given torque command such that total winding copper loss due to stator and rotor currents can be minimized if the exact solution exists; the best approximate torque can be produced if no exact solution exists. The determined current commands are optimal in the sense of energy efficiency or degree of approximation in wide speed‐range operation under voltage limit. New real‐time recursive algorithms searching the optimal current solution are also given. The proposed methods are analytical but practical, and their usefulness is verified through experiments. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(1): 70–83, 2006; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20156     

A simple instant‐estimation method for time‐average quantities of single‐phase power and application to single‐phase power grid connection by inverter

This paper presents and analyzes a new simple instant‐estimation method for time‐average quantities such as rms values of voltage and current, active and reactive powers, and power factor for single‐phase power with the fundamental component of constant or nearly constant frequency by measuring instantaneous values of voltage and current. According to the analyses, the method can instantly estimate time‐average values with accuracy of the fundamental frequency, and estimation accuracy of the power factor is about two times better than that of voltage, current, and powers. The instant‐estimation method is simple and can be easily applied to single‐phase power control systems that are expected to control instantly and continuously power factor on a single‐phase grid by inverter. Based on the proposed instant‐estimation method, two methods for such power control systems are also proposed and their usefulness is verified through simulations. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(2): 34–43, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20236     

Current Control Method of Achieving Wide‐Range Power Driving for Linear Synchronous Motor with Half‐Wave‐Rectified Self‐Excitation

In a previous paper, we proposed a novel linear synchronous motor with half‐wave‐rectified self‐excitation. A long‐stator‐type linear synchronous motor was built and its performance was verified by experiments. This paper presents a new current control method for the linear synchronous motor in order to achieve a wide range of speeds and high‐power operations. First, we propose a current control method for high‐thrust operation in the constant‐thrust region. This operation is realized by using the reluctance thrust resulting from the saliency of the linear synchronous motor. We also propose a control method that maximizes the ratio of the thrust to the voltage; this method can be used to expand the operating range. Wide‐range‐speed operation can be achieved by applying this new control method along with field‐weakening control. The thrust and operating characteristics of the proposed control methods are estimated by performing experiments and coupled electric and magnetic analysis.     

一种表面-内置式永磁转子同步电机三维全域温度场分析

针对表面-内置式永磁转子同步电机(SIPMSM)具有结构紧凑和功率密度高的特点,准确计算SIPMSM各部件的温度分布非常重要。采用电磁场-温度场耦合分析的方法对SIPMSM的三维全域温度场进行计算。建立SIPMSM的电磁场和温度场有限元模型,分析在同步运行速度下负载和永磁体退磁对SIPMSM三维全域温度场的影响,也分析了在额定负载下运行速度对SIPMSM三维全域温度场的影响。通过仿真与实验结果的对比分析,验证了样机模型的合理性和计算结果的正确性。