Current Harmonics Suppression in IPMSMs Considering Rotational Harmonics

Current harmonics suppression exhibits advantages to improve the operational performance and lifetime of machines. Generally, it is recommended to transform current harmonics into the synchronous rotating frames (SRFs) and suppress those using PI or PR regulators. These methods are extensively favored owing to their high parameter robustness. However, these existing SRF regulators commonly ignore the rotational harmonics within rotor angle, which are inevitably induced by the nonsinusoidal machine structures and misaligned traction systems. This oversight could introduce virtual harmonics into SRF currents through coordinate transformation, thereby potentially impeding the effectiveness of harmonics suppression. To tackle such issues, this article proposes an improved current harmonics suppression method. Specifically, this method uses multiple resonant regulators in the fundamental SRF to suppress those current harmonics, while involving reduced computational burden in comparison to the approaches within the multiple harmonic SRFs. Moreover, cascaded high-pass filters (HPFs) are utilized to compensate for rotational harmonics during coordinate transformation. The proposed approach has been experimentally tested to verify its effectiveness in suppressing current harmonics.