Overmodulation Harmonic Modeling and Suppression for Induction Motor Field-Weakening Control With Extended Voltage Tracking Method

The overmodulation strategy can improve the maximum output torque capability of induction motor field-weakening control. However, the harmonic voltages accompanied with the extended voltage would cause the harmonics of current and torque, deteriorating system performance. To reveal the generation mechanism of harmonics, an overmodulation harmonic modeling is proposed based on vector analysis. It is quantitatively proved that the constant extended voltage should be reduced as much as possible to suppress the harmonic when providing the expected torque. On this basis, an extended voltage tracking method is proposed to suppress the harmonic and achieve the high output torque capability according to different operation requirements. The flux current preselection block is designed to preset the steady-state operation point. The expected extended voltage tracking block is designed to set appropriate voltage constraint, thereby redistributing the stator current properly. Finally, the experimental results confirm that the investigated method can improve the steady-state performance with harmonic suppression, and achieve the maximum output torque during the dynamic process and the high-load driving process.