基于状态观测器的永磁同步电机直接转矩预测控制研究

发布时间：2018-07-08 14:05

本文选题：永磁同步电机 + 直接转矩控制　；参考：《中国海洋大学》2014年硕士论文

【摘要】：直接转矩控制（DTC）不需要进行解耦控制，并且结构简单、动态响应快，因而被广泛应用于永磁同步电机中。然而在实际生产过程中，受传统定子磁链观测法的观测精度和时滞现象的影响，永磁同步电机DTC系统的转矩和磁链脉动很大，系统的稳定性能不佳。因此，针对定子磁链观测方法和含有时滞的DTC系统的研究就具有重要的理论意义和实际价值。全文的主要研究内容和创新点如下： 1.研究设计了永磁同步电机定子磁链—定子电流全维状态观测器和降维状态观测器。定子磁链的观测精度直接影响着系统的性能，而低速时直流偏移和电机参数变化等因素又会引起定子磁链观测精度下降。针对此问题，本文首先进行了简单的变量代换，将含有转子位置信号的定子电流方程转化为不含转子位置信号的方程。其次，设计了以定子电流和定子磁链为状态变量的全维观测器，解决了定子磁链易受电机参数影响的问题。然后，为了简化系统结构，又进一步设计了以定子电流和定子磁链为状态变量的降维观测器。最后仿真验证了带有这两种观测器的DTC系统的电机参数鲁棒性好，转矩和磁链脉动小，低速时电机性能得到很大提升。 2.研究了两种直接转矩预测控制方法。针对时滞现象容易引起系统转矩脉动增大的问题，提出了两种预测方法。第一种预测方法是全维状态预测方法，它是在全维观测器的基础上，直接预测出下一周期的定子电流、定子磁链和转矩值，最后和传统的DTC系统一样采用查表法算出电压矢量。第二种预测方法是直接对转矩和磁链幅值预测的方法。该方法结合了矢量控制和DTC的优点，直接对转矩和磁链幅值的平方解耦控制，将给定的转矩和磁链幅值平方作为下一周期的预测值，从而计算出所需要的控制电压。经仿真实验验证，这两种预测方法均可以减小转矩和磁链脉动，，在全范围内实现转矩的有效控制，并且由于第二种预测方法采用了SVPWM方法来控制电机，其响应速度要更快。
[Abstract]:Direct torque control (DTC) is widely used in permanent magnet synchronous motor (PMSM) because of its simple structure, fast dynamic response and no need for decoupling control. However, the torque and flux pulsation of PMSM DTC system is very large and the stability performance of PMSM DTC system is poor due to the influence of the traditional stator flux observation method. Therefore, the study of stator flux observation method and DTC system with time delay has important theoretical and practical value. The main contents and innovations of this paper are as follows: 1. The stator flux chain stator current state observer and reduced order state observer of permanent magnet synchronous motor (PMSM) are studied and designed. The observation accuracy of stator flux directly affects the performance of the system, while the DC offset and motor parameter change at low speed will cause the stator flux observation accuracy to decline. To solve this problem, the stator current equation with rotor position signal is transformed into one without rotor position signal by a simple variable substitution. Secondly, a full-order observer with stator current and stator flux as state variables is designed to solve the problem that stator flux is easily affected by motor parameters. Then, in order to simplify the structure of the system, a reduced-order observer with stator current and stator flux as state variables is designed. Finally, the simulation results show that the DTC system with these two observers has good robustness of motor parameters, small torque and flux ripple, and the motor performance is greatly improved at low speed. 2. Two direct torque predictive control methods are studied. In order to solve the problem of increasing torque ripple caused by delay phenomenon, two prediction methods are proposed. The first method is the full-dimension state prediction method, which directly predicts the stator current, stator flux and torque values of the next cycle on the basis of the full-dimensional observer. Finally, the voltage vector is calculated by the look-up table method, which is the same as the traditional DTC system. The second method is to predict the torque and flux amplitude directly. This method combines the advantages of vector control and DTC, and directly decouples the square of torque and flux chain amplitude. The square of the given torque and flux chain amplitude is taken as the prediction value of the next period, and the required control voltage is calculated. The simulation results show that these two prediction methods can reduce the torque and flux ripple and realize the effective torque control in the whole range. Because the second prediction method uses SVPWM to control the motor, the response speed is faster.
【学位授予单位】：中国海洋大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM341

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