Sensorless controls of salient‐pole permanent magnet synchronous motors using extended electromotive force models

In this paper, we propose a new mathematical model for synchronous motors and a sensorless control method based on it. To control permanent magnet synchronous motors, knowledge of rotor position and velocity are necessary. Heretofore, expensive sensors have been used to detect rotor position information. Although many sensorless control methods based on the electromotive force (EMF) have been developed for non‐salient‐pole permanent magnet motors, they cannot be applied for salient‐pole motors without approximation because of complications in the mathematical model; this is turn may lead to problems of instability. To solve this problem, we propose an extended electromotive force model for synchronous motors. The proposed model has a simple structure, making position estimation possible without approximation. Experimental results show that the proposed model and method are valid. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(3): 55–64, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10257     

Sensorless salient‐pole PM synchronous motor drive in all speed ranges

This paper presents a position sensorless drive of salient‐pole PM synchronous motors in all speed ranges including zero speed. Two position and speed estimation algorithms using the current differences between the actual and the estimated currents are proposed. One is based on the back emf estimation in the medium‐ and high‐speed ranges. Another is based on the position dependency of the winding inductances in the low‐speed ranges including zero speed. The effectiveness of the proposed algorithm has been verified with a six‐pole, 1.5‐kW, 1500‐rpm test motor. Stable sensorless speed control from zero to 3000 rpm within ±100% load torque range was achieved. © 2001 Scripta Technica, Electr Eng Jpn, 135(3): 64–73, 2001     

永磁同步电机初始磁极位置检测方法

根据永磁同步电机相电感的饱和效应,提出了一种恒压源作用下的相电流响应来获得电机初始磁极位置的检测方法,并针对制动器打开瞬间容易出现因磁极位置不准而造成无法定位的问题,对位能性负载提出了一种基于位置环的快速定位法。该方法根据电机实际转动的角度来反向移动给定电流矢量,实现快速定位。最后通过计算不同幅值电流矢量二次定位转过的角度来获得精确的磁极位置。所提方法能够准确获得电机初始磁极位置,可适用于不同类型的永磁电机。实验证明:该控制方法结构简单,易于数字控制实现,同时具有较强的通用性和鲁棒性。     

混合磁极式的混合励磁永磁同步发电机仿真

为了研究混合磁极式的混合励磁永磁同步发电机转子上既有永磁体、又有励磁绕组的运行性能,建立了混合磁极式的混合励磁永磁同步发电机的基本方程;根据该电机的转子结构及定子绕组的实际连接方式和空间分布情况,分析了模型中电感参数及永磁体在其他回路中产生的磁链的特点,并给出其表达式;采用有限元法计算各参数表达式中的系数,能准确考虑磁极形状及永磁体的作用,利用数值方法对该电机的性能进行仿真.在1台混合磁极式的混合励磁永磁同步发电机样机上进行了实验,仿真结果和实验结果吻合较好,验证了仿真模型的正确性和参数计算的准确性.     

Simulation of variable‐speed wind generation system using boost converter of permanent magnet synchronous generator

This paper proposes a variable‐speed wind generation system using the boost converter. The proposed system has three speed control modes for the wind velocity. The control mode of low wind velocity regulates the armature current of the generator with the boost converter to control the speed of wind turbine. The control mode of middle wind velocity regulates the DC link voltage with the vector controlled inverter to control the speed of wind turbine. The control mode of high wind velocity regulates the pitch angle of the wind turbine with the pitch angle control system to control the speed of the wind turbine. The hybrid combination of three control modes extends the variable‐speed range. The proposed system simplifies maintenance, improves reliability, and reduces the costs compared with the variable‐speed wind generation system using a PWM converter. This paper describes the control strategy and modeling for a simulation of the proposed system using Simulink of Matlab. It also describes the control strategy and modeling of a variable‐speed wind generation system using a PWM converter. The steady state and transient responses for wind velocity changes are simulated using Matlab Simulink. This paper verifies the fundamental performance of the system using a boost converter by discussing the simulation results of both systems. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(4): 37–54, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20902     

Performance prediction of a hybrid‐excitation synchronous machine with axially arranged excitation poles and permanent‐magnet poles

This paper presents a method of predicting the steady‐state performance of a new hybrid‐excitation synchronous machine (HESM) theoretically. The field pole of this HESM is axially divided into two parts; one is an excitation part and the other a permanent‐magnet (PM) part. A nonlinear equivalent circuit, which can include the saliency of the rotor and the magnetic saturation due to the iron core, is derived. Based on this equivalent circuit, the steady‐state performance of the HESM is calculated, and the results are confirmed through experiments. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 43–49, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20033     

直驱式永磁同步风力发电机性能研究

通过等效磁路法设计了额定功率1.5MW的直驱式永磁风力发电机;为了深入研究额定功率1.5MW的直驱式永磁风力发电机的运行特性,采用场路结合法分析了永磁风力发电机在空载、额定负载和短路情况下的运行特点,并验证了所设计永磁风力发电机的可行性;在此基础上,将极孤系数、负载变化对永磁同步发电机输出功率的影响进行了仿真;对比研究了每极每相槽数对永磁同步发电机性能的影响.结果表明:极槽匹配对直驱式风力永磁发电机性能有很大影响;通过合理选择极数、槽数以及极弧系数,可以减少输出电压谐波分量的影响,降低永磁材料的使用,节省成本,有助于直驱式风力永磁发电机获得良好的性能.     

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.     

Power maximization control of variable‐speed wind generation system using permanent magnet synchronous generator

This paper proposes sensorless output power maximization control of a wind generation system. A permanent magnet synchronous generator (PMSG) is used as a variable speed generator in the proposed system. The generator torque is suitably controlled according to the generator speed and thus the power from a wind turbine settles down on the maximum power point by the proposed MPPT control method, where the information on wind velocity is not required. Moreover, the maximum available generated power is obtained by the optimum current vector control. The current vector of PMSG is optimally controlled according to the generator speed and the required torque in order to minimize the losses of PMSG considering the voltage and current constraints. The proposed wind power generation system can be achieved without mechanical sensors such as wind velocity detector and a position sensor. Several experimental results show the effectiveness of the proposed control method. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 11–19, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20043     

Three‐dimensional array of strong magnetic field by using cubic permanent magnets

The strong magnetic field arrays by using cubic permanent magnets are proposed as a magnetic field source. The magnets used two types of the magnetized directions: 6 and 18 directions. The array is three‐dimensional structure: cube consisting of three, five, seven, and nine cubic magnets on the side. There are two types of the structures: through‐hole and dead end in the center. For each cube magnet, the magnetic flux density of the center was calculated by the derived formulae, which are solved the area integral by the integral formulae. It is a feature that the calculations are fast. The directions in which the magnetic flux density of the z‐axis is maximized were selected, and the sum of their magnetic flux density was obtained. At the same time, each sum of the magnetic flux density of the x‐axis and y‐axis was selected to be zero. It was found that the obtained results are independent of the length of one side. Therefore, the structures can also be combined to cover the structures. Although the operating point of the magnet is not taken into account, it was able to find the arrangements of more than 2 T. It was confirmed that the array of 24 cubes was consistent with the experiment.     

混合励磁永磁同步发电机的原理与设计

针对普通永磁同步发电机输出电压不可调的不足之处,本文采用一种新颖的电机结构－混合励磁结构,它综合了永磁电机和电励磁电机的优点：发电机在结构上是无刷的;磁场可以调节。对这种电机的结构、工作原理、设计方法等进行了描述,并试制了一台样机,试验结果证明了所提方法的可行性。     

Analysis of magnetic saturation in a salient‐pole synchronous machine after sudden three‐phase short circuit

In order to evaluate magnetic saturation under subtransient and transient states of a large‐sized salient‐pole synchronous machine, the currents and leakage inductances after sudden three‐phase short circuits are analyzed by a two‐dimensional nonlinear transient finite element method (FEM). The currents are calculated both by direct and indirect methods. The direct method uses the FEM and considers fluctuation of the magnetic saturation after the short circuit. The indirect method solves Park's differential equations without fluctuation. Results of the direct method agree well with measurements. When the preshort voltage is large, fluctuation of the leakage inductances after the short is large and it greatly affects values of the short‐circuit currents. As the preshort voltage becomes large, the damper leakage inductances saturate at first, then the field leakage inductances, and finally the armature leakage inductances saturate. Although the indirect method considers saturation under the preshort condition, it gives inaccurate results and they are nearly the same as the results by the linear FEM. In general, it is thought that saturation of the leakage flux should be considered when subtransient conditions with large disturbance are analyzed. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(4): 46–55, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10240     

直驱永磁同步风电机组的最优功率运行控制

构建了直驱永磁同步风电机组的最优功率控制模型,包括低风速下的最大风能捕获控制模型和高风速下的桨距角控制模型.最大风能捕获控制以永磁同步发电机输出功率为反馈量,转速为控制对象,桨距角控制以转速为反馈量,桨距角为控制对象.在PSCAD/EMTDC仿真平台上搭建了相应的仿真系统,对直驱永磁同步风电机组联网运行进行了仿真分析,对所建立的数学模型和最优功率控制方法的有效性进行了验证.     

静止边界法在永磁同步发电机旋转磁场及铁心损耗计算中的应用

旋转磁场分布是永磁同步发电机铁心损耗计算的基础。目前,对于旋转磁场计算一般都是通过建立转子处于不同位置时有限元磁场模型来实现,即模型重构法。这种方法对于每一个转子位置的磁场分析都要重复建模-划分网格,从而使得整个分析过程效率低下。基于此,本文提出一种高效计算同步永磁发电机旋转磁场数的静止边界法,该方法通过改变静止边界节点磁位的耦合顺序来等效转子的旋转,克服了模型重构法电磁计算过程中需反复建立模型所导致效率低下的缺点。通过比较两种方法的计算结果,验证了静止边界法在电机旋转磁场计算中的正确性和高效性。同时静止边界法保证了在旋转磁场的计算过程中,定、转子模型中有限元单元的形状、位置及构成节点信息的一致性,为永磁同步电机铁耗分布的准确计算提供了单元磁密时域解。     

直驱永磁同步风力发电机转子位置测量的研究

针对现有永磁同步发电机的转子位置测量方法,综合各种测量方法的不足,提出了一种增量式光电编码盘的测量方法,并对电机初始位置检测进行了实验与结果分析,实验结果表明了该方法是切实可行的,能够可靠并有效地检测出电机转子的初始位置.     

Calculation of the Characteristics of Salient‐Pole Synchronous Machines Assisted by Permanent Magnets on the Basis of the Operating Principle

In this study we investigate a method for accurately calculating the characteristics of salient‐pole synchronous machines assisted by permanent magnets. First, the operating principle of the machines is investigated by using both finite element analysis and a simple magnetic circuit. Then, a theoretical representation of the assist effect on the permanent magnets is derived based on the magnetic circuit. Finally, the measured and calculated results are compared in order to confirm the validity of the proposed calculation method. We show that the load characteristics of the proposed machine can be accurately estimated from the no‐load and short‐circuit characteristics of the conventional machine without permanent magnets, and the size and magnetization of the inserted permanent magnets.     

宽转速范围永磁同步发电机电流矢量控制

为了实现永磁同步发电机(PMSG)在宽转速范围内和变负载条件下的高性能稳压控制,提出一种基于PWM整流器的PMSG电流矢量控制策略。PMSG输出的不稳定交流电经过PWM整流器变换成稳定的直流电,这样的直流发电系统具有高功率密度、高效率和能量、可双向流动等优点。所述的电流矢量控制策略,具体是在PMSG低速时采用最大转矩/电流比(MTPA)控制,中高速时通过一个电压外环实时补偿d轴弱磁电流,使得PMSG系统能够根据转速和负载变化及时地分配和控制d、q轴电流。仿真和实验结果验证了该控制策略的正确性和有效性,实现系统在宽转速范围的高性能稳压输出。     

Mirror‐phase characteristics of synchronous reluctance motor and salient‐pole orientation methods for sensorless vector controls

In this paper, a mathematical model of the synchronous reluctance motor in a new form is established, followed by a new analysis of stator linkage flux of the motor, which characterizes the motor and plays an essential role in developing new rotor salient‐pole orientation methods for sensorless vector controls. Finally in a unified manner based on the inherent characteristics of the flux, six new potential salient‐pole orientation methods are developed and proposed. © 2002 Scripta Technica, Electr Eng Jpn, 139(2): 61–71, 2002;DOI 10.1002/eej.1153     

Analysis of characteristics of half-wave rectified brushless synchronous motor with permanent magnets

Previously, the authors proposed a “half-wave rectified brushless synchronous motor” as a novel servomotor. The rotor winding emf of the motor is induced by the stator current mmf which rotates at synchronous speed and pulsates at bias frequency. The field excitation is produced by the field current obtained from rectifying the emf with a diode inserted into the field winding. To improve the power factor and the efficiency, they also proposed a new-type half-wave rectified brushless synchronous motor with permanent magnets. This paper analyzes the flux distribution and the torque characteristics of the new half-wave rectified brushless synchronous motor using the finite element method. The computed torque characteristics are confirmed with the experimental results. Furthermore, the steady-state characteristic equations are derived and the effect of the modulation function waveforms on the motor performance is investigated. The theory also is confirmed by the experiments.     

直驱永磁同步风电机组不对称故障穿越的研究

分析电网发生不对称故障对直驱永磁风力发电机组(D-PMSG)的影响,研究其控制策略,以提高其不对称故障穿越的能力。把电网电压实时引入机侧整流器参考功率的计算中,提出了按照电网正序电压和其额定电压的比减小发电机输出功率的控制策略。建立了经背靠背双PWM变流器并网的D-PMSG仿真模型。机侧整流器控制内环采用电流前馈控制,外环采用功率环控制发电机输出功率。网侧逆变器控制内环采用电流前馈控制,并控制负序电流为零,外环采用电压环稳定直流电压。仿真结果表明,在不对称故障时,这种策略保持了发电机功率平衡和变流器功率平衡,限制了直流电压的升高,保持了逆变器三相电流对称,实现了机组不对称故障穿越。