新型单绕组无轴承异步电机控制系统

研究了一种新型结构的单绕组无轴承异步电机,与传统的双绕组无轴承异步电机相比,采用一套绕组即可实现电机转子的悬浮和旋转。在分析单绕组无轴承异步电机新型结构和工作原理的基础上,推导出电机径向悬浮力和转矩部分的数学模型。针对单绕组无轴承异步电机的定子电流连接的复杂性,采用电流叠加控制方法,并设计基于气隙磁场定向控制的控制系统。在MATLAB/Simulink中建立控制系统的仿真模型进行仿真验证,并制作实验样机进行悬浮特性试验。结果表明,该方法控制的样机转速响应好、悬浮特性优良,从而验证了所提方法的正确性与有效性。     

无轴承开关磁阻电机无位移传感器运行研究

无轴承开关磁阻电机具有体积小,无磨损,效率高,功耗低等优点,但机械式传感器限制了电机固有高速性能的发挥。因此,文中研究了一种基于高频电压信号注入的无径向位移传感器控制方法,并建立了基于此算法的电机转子径向位移预测模型,实现无轴承开关磁阻电机无位移传感器稳定悬浮运行。最后,通过仿真和实验分析对所提方法进行了验证。结果表明,所设计控制策略能够正确估计出单绕组无轴承开关磁阻电机的转子径向位移,且系统具有较好的动态响应能力。     

关于讲解"无轴承电机径向悬浮力"

本文在回顾电机中的洛伦兹力和麦克斯韦力基础上,通过介绍无轴承电机基本结构,径向悬浮力产生机理和悬浮力系统的运动方程等来讲解无轴承电机的径向悬浮力,并且介绍了教学过程中的实践经验。通过采用本文的讲解方法,学生易于理解和掌握无轴承电机的结构和径向悬浮力产生原理。     

图解分析法讲解无轴承电机磁悬浮控制原理

在回顾电机中的洛伦兹力和麦克斯韦力基础上,本文通过理论解析介绍了无轴承电机产生稳定径向悬浮力的基本条件。笔者以二极悬浮控制四极无轴承电机为例,针对几个典型时刻产生出的径向磁悬浮力,对无轴承电机磁悬浮控制原理进行了图解分析。教学实践表明,采用本文解析推导和图解分析相结合的讲解方法,便于快速且深入地理解掌握无轴承电机这种新型电机的基本工作原理。     

一种新颖的双三相感应电机缺相运行矢量控制

双三相感应电机的绕组开路后,运用传统的旋转坐标变换,不能实现转子磁场定向矢量控制。本文推导出不对称绕组结构的解耦旋转坐标变换,并提出了一种基于不对称绕组结构的转子磁场定向矢量控制新颖策略,运用PI调节器,使得定子侧谐波电流最小化,降低定子侧谐波损耗。在MATLAB MATLAB/Simulink仿真软件下,建立相应的仿真模型,仿真结果验证本文所提出控制策略的正确性和有效性。     

单绕组磁悬浮开关磁阻电机低铜耗发电研究

为减小单绕组磁悬浮开关磁阻电发电机(SWBSRG)保持悬浮时绕组的铜耗,以及解决励磁不平衡时续流发电区间悬浮不可控问题,提出了一种新的悬浮发电控制策略。该控制策略可降低悬浮过程中绕组的铜耗。并通过对悬浮、励磁、发电区间的划分和区间时长的推导来解决续流发电区间悬浮不可控问题。通过Simplorer和Maxwell的联合仿真验证了此种低铜耗悬浮发电原理的正确性以及转子径向位移具有较好的悬浮收敛性,并通过反馈控制励磁电流来实现对输出电压的良好控制。     

基于有限元分析的直流电机控制策略

无轴承无刷直流电机集成了直流和交流电机的优点,具有重要的实际应用价值,针对传统悬浮力控制方法存在工作复杂、逆变器通断频繁等缺陷,为了提高磁悬浮力的控制效果,提出了基于有限元分析的无轴承无刷直流电机悬浮力控制策略。首先对无轴承无刷直流电机的结构以及悬浮力产生的原理进行了分析,然后采用有限元分析法对电机转矩和悬浮力进行计算,从而实现无轴承无刷直流电机控制,最后采用Matlab/Simulink工具对其性能进行测试与验证。结果表明,本文策略可以提高转子悬浮的稳定性,能够保证无轴承无刷直流电机的正常运行。     

单绕组磁悬浮开关磁阻电机无位置传感器研究

由于位置传感器成本高,受温度和噪声的干扰,增加电机结构的复杂度等缺点,文中研究了一种高性能实用的无位置传感器方法,利用单绕组磁悬浮开关磁阻电机相绕组之间的互感和位移的关系,将一高频测试电流注入A相的任一极,引起在相邻两极的端电压互感增量,滤除互感电压并经过滤波器解调得到包含转子位移的直流部分,然后经过数学处理得到转子位移,实现径向位移自检测,最后通过实验验证该方法的正确性和有效性。     

基于微机械工艺的平面微电机的研究

为提高微电机的输出力矩，增加微电机散热能力和电流密度，提高电机工作效率，设计了一种具有双转子结构的平面微电机。两个转子对称分布于定子两侧。转子采用永磁体进行轴向充磁。定子为平面线圈，是采用硅微机械加工技术和LIGA工艺制作的。线圈之间则采用了三相星形连接方式，线圈结构为平面型、无槽、集中绕组。把制作好的定子和转子装配后通以三相方波电流进行驱动，通过对其输出力矩和转速的测试证明电机运转良好。     

矢量控制电流环的内模解耦控制

电机矢量控制虽然实现了励磁电流和转矩电流解耦,但交流电机内部M轴和T轴之间存在交叉耦合电压及转子温升造成矢量控制条件的破坏.提出采用定子电流解耦的内模控制,推导出其设计过程和控制器型式,通过数字仿真论述了感应电动机定子电流控制系统采用解耦内模控制,可有效抑制干扰及模型失配对输出的影响,增强系统对给定信号的跟踪能力.     

A Study of Influence of Configurations of the Windings on the Performance of Single Phase Induction Motor with Capacitor Start

The single phase induction motors needs two stator windings to produce rotating magnetic field : one main winding and the other auxiliary winding. The aim of the auxiliary winding is to create the rotating electromagnetic field when the machine is started-up and is afterwards turned off, generally through the centrifugal switch coupled together with the shaft of the machine rotor. The main purpose of this document is to evaluate the influence that the two windings have on the external characteristics of the single phase induction motor . For this purpose , two different kinds of windings were carried out and simulated, with the proposal to obtain some benefits. The main winding and the auxiliary winding were prepared and mounted on a prototype. The simulation was done via software based FEM , to make the extraction and results analysis possible. This results are shown at the end this document.     

Modeling and Real-Time Simulation of Internal Faults in Synchronous Generators With Parallel-Connected Windings

In large synchronous generators, the stator windings are usually parallel-connected in order to increase the machine current capacity. In analysis and modeling, the parallel windings are usually lumped into one equivalent stator winding since equal currents flow in these windings. However, when an internal fault occurs in the windings, the symmetry between the parallel windings is broken and different currents will flow in the parallel windings since unsymmetrical magnetic linkage may exist between the stator windings. The aim of this paper is to present a simulation model to investigate the internal fault currents of large synchronous generators with parallel-connected windings. This model is based on a modified winding function theory that takes into account all space harmonics. Moreover, the calculation of the machine inductances is made easier by the use of the machine electrical parameters instead of the geometrical ones. The simulation results illustrate the existence of different currents in parallel windings in the case of internal faults. Results are given for an implementation of the internal fault model in a real-time simulator of large power networks     

Design and analysis of permanent magnet-type bearingless motors

Magnetic bearings have been applied to high speed and high power electric machines for machine tools, turbomolecular pumps, etc. Bearingless motors can be expected to realize high speed and high power ratings because magnetic bearing functions are integrated into high-speed motors, which results in a simplified structure with short shaft length. In this paper, permanent magnet type bearingless motors, having built-in capability to achieve high power factor and high efficiency, are proposed. The shaft is suspended and centered by electromagnetic forces produced by currents in the additional radial force windings of the stator slots. At first the relationships of these radial forces, currents and voltages are derived analytically. Moreover, the relationships between radial forces and permanent magnet thickness are found. The optimal permanent magnet thickness is determined. The ratio of radial force over current as well as the peak air-gap flux density are discussed. These relationships are confirmed by prototype machines     

Efficiency Analysis of PWM Inverter Fed Three-Phase and Dual Three-Phase High Frequency Induction Machines for Low/Medium Power Applications

A performance analysis of three-phase and dual three-phase (DTP) induction pulsewidth modulation (PWM) inverter-fed motor drives is conducted in this paper. The focus is on the efficiency performance of high-frequency DTP machines compared to their three-phase counterparts in low/medium power applications. For this purpose, a DTP machine, having two sets of stator three-phase windings spatially shifted by 30 electrical degrees (asymmetrical six-phase winding configuration), was tested for both six-phase and three-phase winding configurations under the same magnetic conditions. Simulation and experimental results are presented to evaluate the efficiency performance of three-phase and dual-three induction motor drives employing PWM voltage source inverters.     

20MJ补偿脉冲发电机的设计与仿真

由于补偿脉冲发电机集惯性储能、机电能量转换和脉冲成形的综合技术优势,研制了一台额定转速为12 000 r/min的20 MJ补偿脉冲发电机,并研究了其中关键材料包括屏蔽筒和转轴等的选择。在理论计算和仿真分析的基础上设计了电机励磁回路以及电枢绕组,提出了一种新的补偿绕组结构即定子上安放两套电枢绕组,在电机放电时,脉冲电流将会提高,绕组的温度会降低,磁场密度会增强。     

Optimizing current control performance in double windingasynchronous motors in large power inverter drives

The operation of AC drives in applications requiring high overload capability imposes hard working conditions on the electronic switching devices. The use of induction motors with two stator windings, fed by two inverter modules, allows large power rating in variable speed drives for high performance applications. This paper shows the structure and the main features of a field-oriented control for a double winding motor, fed by two GTO inverters. The operational results of an 850 kW drive, working as a melt pump in a polyethylene plant, are reported in order to describe the obtained performances     

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     

Design and analysis of a novel wound rotor for a bearingless induction motor

The traditional squirrel-type bearingless induction motor (BIM) suspension winding generates induced current in its squirrel-cage rotor and affects the phase and amplitude of the suspension force. Based on the analysis of the spatial distribution of torque winding magnetic field and suspension winding magnetic field, a new type of wound rotor BIM is designed. Different from the squirrel-cage rotor, the wound rotor uses a special method of embedding a set of coils at any symmetrical four rotor slot positions, so as to only induce the torque winding magnetic field. The induced current, air-gap magnetic density, magnetic field line distribution, suspension force as well as electromagnetic torque of the traditional squirrel-cage motor and the new wound motor are analysed by Maxwell finite element calculation. The results show that the designed new wound BIM can not only effectively suppress the induced current of suspension winding, eliminating its influence on the suspension force, but also has a better starting performance.     

Design aspects of bearingless slice motors

The complexity of a bearingless motor offers a multitude of freedoms in constructive design because different motor setups may have nearly the same dynamic behavior, and may differ only slightly in some operation characteristic. However, the mechanical setup often has a very strong impact on the power inverter topology and the volt-ampere requirements, thereby affecting the system costs significantly. This paper focuses on design aspects of bearingless slice motors with permanent magnet excitation, and presents a methodical evaluation approach based on performance indexes.