Analysis of brushless permanent magnet synchronous motors

A brief design review of permanent magnet synchronous motors has been presented. A procedure has been developed to predict the steady state and dynamic performances of a brushless permanent magnet synchronous motor. Finite element analysis has been combined with a lumped parameter circuit model in order to provide satisfactory engineering information. To this end, two coordinated steps are involved. One is to develop a unified lumped parameter circuit model for both steady state and dynamic analysis. The second step is to extract the individual lumped parameters from finite element solutions based on corresponding equivalent circuits, each with a pre-determined topology. The proposed techniques have been experimentally verified in a laboratory permanent magnet synchronous motor     

轮毂盘式无铁心永磁同步电机永磁体结构优化

从优化永磁体结构的角度出发,提出将不等厚排列技术与90°Halbach阵列相结合方法对磁钢的排列结构分析,通过改变磁钢排列结构以进一步提高盘式无铁心永磁同步电机(以下简称为DCPMSM)气隙磁密的基波幅值及波形的正弦性,达到提高电机性能的目的.本文通过有限元仿真软件对16极盘式永磁同步电机进行建模,分别选取不等厚排列电机模型、不等宽90°Halbach排列电机模型和改进型90°Halbach排列电机模型进行静态气隙磁场分析对比.仿真数据表明,"不等厚排列技术+90°Halbach阵列"使得周向磁密波形和切向磁密波形都大为改善,磁场波形更接近于正弦分布特征,其中周向磁密波形畸变率(THD)Bmin可降低到1.35%,气隙周向磁密幅值Bδav提高到0.5465T.     

Analysis of direct torque control in permanent magnet synchronousmotor drives

This paper describes an investigation of direct torque control (DTC) for permanent magnet synchronous motor (PMSM) drives. It is mathematically proven that the increase of electromagnetic torque in a permanent magnet motor is proportional to the increase of the angle between the stator and rotor flux linkages, and, therefore, the fast torque response can be obtained by adjusting the rotating speed of the stator flux linkage as fast as possible. It is also shown that the zero voltage vectors should not be used, and stator flux linkage should be kept moving with respect to the rotor flux linkage all the time. The implementation of DTC in the permanent magnet motor is discussed, and it is found that for DTC using available digital signal processors (DSPs), it is advantageous to have a motor with a high ratio of the rated stator flux linkage to stator voltage. The simulation results verify the proposed control and also show that the torque response under DTC is much faster than the one under current control     

Modeling of permanent magnet motor drives

Research has indicated that the permanent magnet motor drives, which include the permanent magnet synchronous motor (PMSM) and the brushless DC motor (BDCM) could become serious competitors to the induction motor for servo applications. The PMSM has a sinusoidal back EMF and requires sinusoidal stator currents to produce constant torque while the BDCM has a trapezoidal back EMF and requires rectangular stator currents to produce constant torque. The PMSM is very similar to the wound rotor synchronous machine except that the PMSM that is used for servo applications tends not to have any damper windings and excitation is provided by a permanent magnet instead of a field winding. Hence the d, q model of the PMSM can be derived from the well-known model of the synchronous machine with the equations of the damper windings and field current dynamics removed. Because of the nonsinusoidal variation of the mutual inductances between the stator and rotor in the BDCM, it is also shown that no particular advantage exists in transforming the abc equations of the BCDM to the d, q frame. Hence the solution of the original abc equations is proposed for the BDCM     

直流永磁式测速发电机的程序设计

在工程实际中,永磁直流测速发电机的设计由于其考虑因素较多,要求精度高,计算量大,而使设计工作冗繁,错误率较高.根据手算程序用C语言编写了计算机程序.本程序应用范围比较广,可对不同技术指标要求的永磁直流测速发电机进行设计计算,可读性较强.     

Development of high field permanent magnet

Permanent magnets are believed to be applicable only to make small and weak magnets. It is possible, however, to make a magnet with much higher strength than those in the past by introducing a saturated iron pole. Cooling down the magnet further enhances the field strength to a great extent. We have demonstrated that a permanent dipole magnet exceeding a typical permanent magnet more than by factor 3 is possible. A new challenge is to conceive such magnet for an accelerator application where time dependent alternating field is often requested.     

永磁式直流测速发电机的特点

随着新型永磁材料的不断产生和应用,永磁式直流电动机也越来越被广泛地应用于各行各业。永磁式直流测速发电机在低速控制系统中被作为反馈元件或稳速元件。它除具有一般测速发电机的优点以外,还具有结构简单、紧凑,反馈灵敏度高,低速精确度高,输出斜率大,线性误差小,可靠性好,寿命长等特点。介绍了永磁直流测速发电机的设计及其主要特点。     

单相三绕组永磁同步电动机的起动性能分析

推导出永磁同步电动机的定子侧绕组的电压约束方程式,建立三绕组永磁同步电动机在d-q-0坐标系下的动态数学模型,对电机的起动瞬态特性进行分析;运用对称分量法分析三相永磁同步电动机的电路系统,计算起动和运行时需要的电容值;根据牵入同步判据,计算不同负载下所能牵入同步的最大转动惯量。通过实例对三绕组永磁同步电动机牵动负载的起动过程进行仿真分析,结果表明在单相电源供电系统下,可以选择合适的电容值使其起动和运行。     

NdFeB永磁靶材溅射模拟

运用SRIM2006软件对Nd2Fe14B靶溅射过程进行了模拟,并就入射离子的入射能量和角度进行了分析,得到溅射产额与入射离子能量、入射角度以及溅射靶材的一般规律:1)溅射产额随着入射离子能量的增加而增加,在低能量区域增加很快,到了高能量区域增加变缓;2)溅射产额随着入射离子入射角度的增大逐渐增大,且在70°~80°出现极大值,如当入射离子的入射角度为75°,入射离子能量为7 keV时,溅射产额可达4.398(原子.离子–1);3)溅射原子的摩尔比与靶材原子摩尔比存在一定偏差,导致薄膜成分与靶材成分不一致。     

永磁同步电机优化控制

为了推进永磁同步电机在实际工程领域的应用,通过Matlab软件搭建了基于滑模变结构的永磁同步电机控制模型.为了使控制效果更加理想,提出了一种优化的指数滑模速度控制器,并针对这种连续的速度控制器在控制系统中进行了仿真.仿真结果表明,控制效果得到了很大改善.     

永磁被动补偿脉冲发电机设计与仿真

采用永磁励磁、两极两相、被动补偿结构，设计了一台小型补偿脉冲发电机。使用有限元软件对电机进行空负载电磁特性分析；永磁体采用厚度为12 mm的钕铁硼材料，空载时气隙最大磁感应强度为0.443 T。在60 000 r/min的设计转速下，单相开路电压峰值为195.4 V，铁心损耗功率为599 W。对电阻值1 mΩ，电感值1 μH的小阻抗负载分别进行了单相放电、两相并联放电及两相串联放电仿真，单相放电电流峰值为10.90 kA，脉宽0.78 ms；两相并联放电电流峰值14.64 kA，脉宽1.1 ms；串联放电电压峰值增至333.7 V，电流峰值为8.59 kA。电机储能大于4 MJ，脉冲功率大于2 MW，且结构紧凑，具有较高的能量密度和功率密度。     

永磁同步电机的弱磁控制方法

永磁同步电机（PMSM）是最流行的电机,例如作为高速电动列车的牵引电机,源于其高转矩电流比的特性和能够通过弱磁控制扩大恒功率区域的能力,矢量控制理论的发明是交流调速领域中的一个重大突破,文中将详细讨论永磁同步电动机的矢量控制,在推导其精确数学模型的基础上分析了矢量控制理论用于永磁同步电动机控制的几种电路控制策略,包括了id=0控制,最大转矩/电流控制,最大输出功率控制,最小磁链转矩比控制,最大电压转矩比等.     

High-speed torque control of brushless permanent magnet motors

A method of converter control that improves the high-speed torque of brushless permanent-magnet (PM) motors is presented. The method consists of modulating the converter conduction intervals and their phase relative to the rotor position in order to deliver current to the stator windings at high speeds where the motor back EMF approaches the convertor rating. A microprocessor-based controller is used in the implementation. With this control, operation of the PM motor drive at its maximum ratings can be extended to higher speeds     

Loss minimization control of permanent magnet synchronous motordrives

This paper aims to improve efficiency in permanent magnet synchronous (PM) motor drives. The controllable electrical loss which consists of the copper loss and the iron loss can be minimized by the optimal control of the armature current vector. The control algorithm of the current vector minimizing the electrical loss is proposed and the optimal current vector can be decided according to the operating speed and the load conditions. The proposed control algorithm is applied to the experimental PM motor drive system, in which one digital signal processor is employed to execute the control algorithms, and several drive tests are carried out. The operating characteristics controlled by the loss minimization control algorithm are examined in detail by computer simulations and experimental results     

Design and control of a permanent magnet spherical wheel motor

We present a permanent magnet–based spherical wheel motor that can be used in omnidirectional mobility applications. The proposed motor consists of a ball‐shaped rotor with a magnetic dipole and a hemispherical shell with circumferential air‐core coils attached to the outer surface acting as a stator. Based on the rotational symmetry of the rotor poles and stator coils, we are able to model the rotor poles and stator coils as dipoles. A simple physical model constructed based on a torque model enables fast numerical simulations of motor dynamics. Based on these numerical simulations, we test various control schemes that enable constant‐speed rotation along arbitrary axes with small rotational attitude error. Torque analysis reveals that the back electromotive force induced in the coils can be used to construct a control scheme that achieves the desired results. Numerical simulations of trajectories confirm that even without explicit methods for correcting the rotational attitude error, it is possible to drive the motor with a low attitude error (<5°) using the proposed control scheme.     

Submillimeter p-Ge laser using a Voigt-configured permanent magnet

A p-Ge laser at 170-200 μm wavelengths in Voigt configuration using a regular permanent magnet is reported. Results are compared with those obtained using a Faraday-configured superconducting magnet. Emission is observed over a wider range of electric-field magnitude in Voigt configuration at a given magnetic field. Time-resolved emission studies reveal unusual pulse dynamics which depend on the magnitude and duration of the applied electric field. Spectral content, Gaussian-beam profiles, and polarization are essentially independent of these temporal effects. A significant repetition-rate increase is found using copper heat sinks. An increased emission-pulse delay with increasing initial-sample temperature and the temperature independence of the emission quench time are both explained by Joule heating of the laser medium. Lasing persists above 10 K, raising the possibility of a practical p-Ge laser without need for liquid helium as a coolant     

一种用于氪原子的环形永磁体塞曼减速器

基于激光冷却与囚禁原理的原子阱痕量分析技术,可以对氪的放射性同位素进行高灵敏度检测,在地球物理与环境科学领域具有广泛应用。塞曼减速器可用于产生连续低速的原子束流,是原子阱痕量分析系统中的关键部件之一。采用永磁体设计的塞曼减速器组装和调试方便,磁场强度稳定,且不需要恒流电源和冷却装置,因此获得了越来越多的关注和研究。文中基于环形永磁体设计了一种用于氪原子的塞曼减速器,通过有限元分析得到了减速器磁场的空间分布,根据设计参数制造了环形永磁体塞曼减速器,测量了轴线上的磁场分布。减速器长度51.2 cm,有效减速区域长度46.9 cm,实测磁场与理论减速磁场最大偏差小于3.6 G,平均偏差1.3 G。进一步模拟了原子束流在设计磁场和实测磁场下的减速过程,并分析了磁场的径向变化对于原子束流减速的影响规律,结果表明:当原子束流直径小于20 mm时,该塞曼减速器可将初速度最大为250 m/s的氪原子减速至50 m/s。     

Current phase control methods for permanent magnet synchronousmotors

Three types of current phase control methods are examined for the interior magnet motor and the surface magnet motor: (1) the i _d=0 control method, (2) the cos φ=1 control method, and (3) the constant-flux-linkage control method. The control circuits for realizing these control methods were investigated and a drive test carried out. The most suitable current phase control method for the rotor geometry was examined by computer simulation and experimentation. It was found that in the i_d=0 control method, high-performance torque control can be obtained as the torque is proportional to the armature current. In the cos φ=1 control method, the torque per armature current is small and the torque characteristic is nonlinear. Therefore, high-performance torque control cannot be expected. The constant-flux-linkage control method is desirable for interior magnet motors as the torque characteristic is almost linear and the required inverter capacity is comparatively small