无轴承异步电机新型直接转矩控制研究

针对无轴承异步电机(Bearingless Induction Motor,BIM)传统直接转矩控制中转矩脉动大,悬浮性能不佳等问题,提出了一种基于滑模变结构的直接转矩控制方法 (SMVS-DTC)。首先根据转矩误差和磁链误差构造出相应的滑模切换面,然后采用指数趋近律设计了直接转矩控制器。在此基础上对所提方法进行了仿真和实验研究。仿真和实验结果表明,该方法有效地减小了转矩脉动和磁链脉动,并且提高了BIM转速动态响应和稳定悬浮性能。     

两相异步电机绕组结构对气隙磁场的影响

研究了两相异步电机不同的绕组结构对气隙磁场谐波的影响。应用Ansoft软件中的MAXWELL模块建立了两相异步电机的有限元模型,并进行了气隙磁场的有限元计算,利用MATLAB程序对有限元计算的数据进行分析,对分析结果进行对比,获得减少谐波的结构。     

无轴承异步电机无速度传感器控制

为解决无轴承异步电机运行中转速辨识问题,提出了一种可以同时在线估计转子电阻和转速的方法。该方法首先通过电压型转子磁链模型估计出转子磁链,然后根据静止坐标系下的无轴承异步电机模型和电压型转子磁链模型推出包含转子电阻和转速的表达式,再将这两个表达式看作一个二元一次方程组并求解,最终得到转子电阻跟转速的解析表达式。最后应用这种转速估计方法构建无轴承异步电机无速度传感器控制系统,并开展仿真研究。仿真结果表明:所提方法能够实现无轴承异步电机转子电阻和转速的准确估计,并保证无轴承异步电机的稳定悬浮运行。     

三电平SVM-DTC的无轴承异步电机研究

针对无轴承异步电机多变量、非线性、强耦合的特性,直接转矩控制(DTC)优秀的控制的特点已经成为一种突出的无轴承异步电机控制性能方案。常规的两电平逆变器具有高的转矩脉动和大谐波的问题,三电平中点钳位逆变器(NPC)广泛应用于变频调速系统,其特点是逆变器开关器件分压使得器件端电压幅值降低,输出纹波脉动,控制性能优良,因此文中通过使用三电平逆变器的空间矢量调制用于直接转矩控制(SVM-DTC)来抑制电机定子转矩脉动。仿真结果表明,三电平逆变器的SVM-DTC能够有效地使无轴承异步电动机稳定悬浮,并且SVM-DTC能有效的抑制转矩脉动和转子的径向位移,提高了系统的精准度并保持了DTC系统的快速转速动态响应。     

基于改进电压法的无轴承异步电机位移辨识

无轴承异步电机在运行过程中对转子径向位移实时反馈是必不可少的,文中就径向位移的测量问题,提出一种基于改进电压模型法的转子径向位移测量新策略。该策略在电压模型法的基础上,用低通滤波器替换电压模型中的纯积分环节,进而利用电感矩阵和转子径向位移之间的关系,设计出转子位移估计器,从而实现准确测量转子位移的目的。运用该策略对无轴承异步电机矢量控制系统进行了仿真,仿真结果表明:该策略能够准确检测出转子径向位移,并且具有优良的转矩特性和转速响应,达到了预期的效果。试验结果同样表明,该策略能够有效检测出转子的径向位移,验证了所提策略的实用性。     

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。     

新型异步电机无速度传感器低速控制算法

基于数学模型的速度估算是异步电机无速度传感器控制的核心。目前,围绕速度估算这个问题,在电机控制领域已出现模型参考自适应、自适应观测器以及扩展卡尔曼滤波等多种方法。无论采用哪种速度估算技术,速度估算系统的动静态性能、低速性能、对参数的敏感性、算法的复杂程度及实现难度都是工程师必须考虑的几个重要性能指标。文中针对低速条件下的异步电机速度估算及控制提出了一种基于无功功率闭环的异步电机无速度传感器矢量控制算法,并探讨了该方法的一些性能指标问题。     

新型无速度传感器的异步电机矢量控制变频器

对于文献所提出的新型无速度传感器的异步电机矢量控制变频调速技术，本文示出了一些重要的仿真结果，并对其进行了评述。     

异步电机的无速度传感器控制系统

根据空间矢量脉宽调制技术和无速度传感器矢量控制原理,提出了电压与电流互补模型的磁链估计,能在全速度范围内得到较好的磁通及转速估计。采用TMS320F2812实现了异步电机无速度传感器矢量控制系统,给出了硬件和软件设计方案。实验表明系统动态性能强,稳定性好,具有很好的应用前景。     

一种具有容错功能的无轴承薄片电机的原理及其实现

本文研究了一种可以实现容错功能的无轴承薄片电机的工作原理和结构设计。详细推导了当无轴承薄片电机在采用单绕组结构并采用定子绕组电流功率最优约束下的径向悬浮力和转矩的数学模型,并由此推导出了电机在绕组完整和绕组故障时的不同定子电流模型,同时给出了相应的控制策略和样机系统设计。实验样机调试结果表明：采用单绕组结构的无轴承薄片电机成功实现了转子在径向、轴向和扭转方向上的5自由度全悬浮。     

单绕组磁悬浮开关磁阻电机结构优化设计

针对单绕组磁悬浮开关磁阻电机结构参数的优化问题,提出了基于相关向量机与混合粒子群优化的方法。通过有限元分析计算了电机悬浮力和转矩与结构参数的关系,构建基于相关向量机非参数模型。以电机平均悬浮力和平均转矩最大输出为优化目标,采用混合粒子群优化算法获取最优结构参数,通过对比仿真实验说明了该算法的准确性与优越性,电机性能得到明显提升。     

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.     

Speed-sensorless control system of a bearingless induction motor based on iterative central difference Kalman filter

ABSTRACT

In order to obtain speed self-detecting with low cost for a bearingless induction motor (BIM) a speed-sensorless control strategy based on the iterative central difference Kalman filter (ICDKF) is proposed. Firstly, on the basis of the BIM mathematical model, the nonlinear state equation is established and its order is reduced from fifth-order to fourth-order using the stator terminal voltage and current as input. Then, a sterling interpolation formulation is used in the filter to reduce the model error, and an iteration loop link is adopted to improve the filter accuracy. Finally, the online speed of the BIM is identified through the filter rotor speed estimation. Theoretical analysis, simulation and experimental results by UKF and CDKF method have been compared. The results show that the proposed speed-sensorless control system not only has good speed tracking performance and reduce the load disturbance but also improves the BIM suspension performance.     

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。     

A novel bearingless interior permanent magnet slice motor driven blood pump

A 2-pole bearingless interior permanent magnet (IPM) motor with slice rotor configuration is presented in this paper. A novel IPM rotor is designed considering direct and indirect operational specifications such as force constant, torque constant, axial/radial stiffness and cogging torque. Cogging torque and its resulting vibrations affect motor and levitation operation significantly. Hence, various rotor configurations are simulated using the finite element method to develop a topology that minimizes these phenomena. The final topology is tested for closed-loop levitation and speed control. The motor is also tested for its intended application as a blood pump. A mock circulatory loop is developed to measure the performance of the pump. The simulation results, experimental control system performance and pump performance results are shown and explained in the paper.     

Speed sensorless control of a bearingless induction motor with combined neural network and fractional sliding mode

To address the problem of speed and flux observation in sensorless control of a bearingless induction motor under the influence of parameter changes and external disturbances, a speed sensorless control strategy combining radial basis function (radial basis function, RBF) neural network and fractional sliding mode is proposed. According to the current error, fractional sliding mode control rate is designed to reduce the speed-observed chatter of the bearingless induction motor and its adverse effect on the rotor suspension stability. Then, combined with the theory of RBF neural network, the new optimal control rate is obtained by using its approximation ability. At the same time, the stability of two control rate is proved. Thus, the flux linkage and speed under normal operation, parameter change and external disturbance are observed and the new speed sensorless control is realized. The simulation and experimental results show that the proposed joint RBF neural network approximation algorithm and fractional sliding mode speed sensorless control system of the bearingless induction motor can not only effectively identify the flux and speed under three conditions of no-load, load disturbance and speed change, but also ensure the good suspension of the motor rotor in the x-axis and y-axis directions.