矩形边界限定形式的感应电机低开关频率预测控制研究

Research on Low Switching Frequency Predictive Control Induction Motor Drive Based on Rectangular Boundary Restriction

圆形边界限定形式预测控制对电流畸变的限定在各方向均相同,无法通过增大边界圆半径进一步降低开关频率。因此,该文提出一种矩形边界限定形式的预测控制方法。首先,深入分析感应电机数学模型,发现感应电机转子子系统的低通物理特性,以及励磁电流波动对电磁转矩的影响不显著;其次,利用该特性,将限定边界改为矩形,对转矩电流与励磁电流进行独立约束,适度增加励磁电流畸变允许限值,扩大电流轨迹运动范围,延长开关状态切换时长;再次,探究电流矢量梯度同边界约束间的数学关系,提出该方法下电压矢量筛选与寻优准则,筛选出最优矢量;最终,进行实验对比。实验结果证明,在相同系统动态特性和转矩波动下,相较于圆形边界限定策略,矩形边界限定策略可以进一步降低开关频率。

The circular boundary restriction predictive control imposes the same limitation on current distortion in all directions,and it is not possible to further reduce the switching frequency by increasing the radius of the boundary circle.This paper proposes a rectangular boundary restriction predictive control method.First,the mathematical model of the induction motor is analyzed,revealing the low-pass physical characteristics of the rotor subsystem of the induction motor,where the fluctuation of the excitation current has a negligible impact on the electromagnetic torque.Then,leveraging the inherent characteristics of the induction motor,the boundary constraint is changed to a rectangular shape,independently constraining the torque current and the excitation current,moderately increasing the distortion tolerance limit of the excitation current,expanding the range of current trajectory motion,and prolonging the duration of switching state transitions.Next,the mathematical relationship between the current vector gradient and the boundary constraint is explored in detail,and the voltage vector filtering and optimization criteria under this method are proposed to select the optimal vector.Finally,experimental comparisons are conducted,and the results demonstrate that,under the same system dynamic characteristics and torque fluctuation,compared to the circular boundary-constrained strategy,the rectangular boundaryconstrained strategy can further reduce the switching frequency.