永磁同步电机无差拍直接转矩控制系统研究

System of dead-beat direct torque control of permanent magnet synchronous motor

针对传统永磁同步电机(PMSM)直接转矩控制(DTC)中存在的磁链、转矩脉动大、开关频率不固定等问题,提出了一种永磁同步电机的无差拍直接转矩控制(DB-DTC)方法,在离散化电机方程基础上利用无差拍控制原理计算出电压矢量,并结合了空间矢量调制技术(SVM)产生开关信号控制电机运行。同时针对离散系统运算耗时所带来的控制周期的误差,进一步基于永磁体同步电机数学模型,提出了一种电流观测器以预测下一控制周期的电流值,目的是准确估计定子磁链和转矩。研究结果表明,所提出的PMSM DB-DTC不仅继承了传统DTC动态响应快的优点,而且能极大程度地削弱定子磁链和转矩的脉动,该系统具有良好的动静态性能,电流观测器能预测定子电流,确保了PMSM DB-DTC系统的控制精度。

In order to solve the problems existed in the traditional direct torque control（DTC）,such as high flux and torque ripples and unfixed switching frequency, a dead-beat direct torque control（DB-DTC）was proposed to control the permanent magnet synchronous motor （PMSM）. The DB-DTC scheme used the discretization equation of PMSM and the principle of dead-beat control to calculate the voltage vector, then SVM technique was combined to generate switching signals. Moreover, in order to eliminate the control period error brought by the time-consuming of discrete system calculation, a current observer was introduced to predict the current value in the next period, so as to precisely evaluate the stator flux and torque. The experimental results confirmed the effectiveness of the scheme proposed. The DB- DTC system has good dynamic and static performance, and the current observer can predict the stator current to ensure the control precision.