Research on Low Switching Frequency Predictive Control Induction Motor Drive Based on Rectangular Boundary Restriction
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 boundary-constrained strategy can further reduce the switching frequency.
rectangular boundarylow switching frequencypredictive controlinduction motor
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