LAUSR

This Letter proposes an improved repetitive controller based on Lagrangian interpolation method to suppress harmonic current in the permanent magnet synchronous motor. Harmonic current suppression performance is degraded drastically if the ratio of the sampling rate to the fundamental frequency of harmonic current is fractional. The fractional-order delay link based on Lagrange interpolation is used to approximate the delay link which is composed of the fractional part of the frequency ratio. In order to further reduce the tracking error of the current harmonics, the low-pass filter located inside the traditional repetitive controller is removed and the stability of the system is ensured by adding a phase compensator. Finally, the experimental results demonstrate the effectiveness of the proposed scheme.